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Environmental Monitoring and Assessment (2005) 107: 259–284

DOI: 10.1007/s10661-005-3109-z c Springer 2005

ARSENIC SPECIATION ANALYSIS IN WATER SAMPLES: A REVIEW

OF THE HYPHENATED TECHNIQUES

EWA TERLECKA Institute of Meteorology and Water Management, ul. Parkowa 30, Wroclaw, Poland

(e-mail: [email protected])

(Received 16 February 2004; accepted 31 August 2004)

Abstract. Interests in the determination of different arsenic species in natural waters is caused by

the fact that toxic effects of arsenic are connected with its chemical forms and oxidation states.

In determinations of water samples inorganic arsenate (As(III), As(V)), methylated metabolities

(MMAA, DMAA) and other organic forms such as AsB, AsC, arsenosugars or arsenic containing

lipids have the most importance. This article provides information about occurrence of the dominant

arsenic forms in various water environments. The main factors controlling arsenic speciation in water

are described.The quantification of speciesis difficult because the concentrations of different forms in

water samples arerelativelylow compared to thedetectionlimits of theavailable analytical techniques.

Several hyphenated methods used in arsenic speciation analysis are described. Specific advantages

and disadvantagesof methods can define their application for a particular sample analysis. Insufficient

selectivity and sensitivity of arsenic speciation methods cause searching for a new or modifications

already existing techniques. Some aspects of improvement and modifications of the methods are

highlighted.

Keywords: arsenic speciation, hydride generation, hyphenated techniques, water analysis

1. Arsenic Speciation in Natural Water Environment

Arsenic contamination in natural waters is a world problem. The content of As in

water depends on natural processes such as weathering of arsenic-rich geological

forms reactions,biological activity and volcanicemissions, as well as anthropogenic

activities. Most environmental arsenic problems are the result of natural condi-

tions; however, man has had an important impact (combustion of fuels, mining

activity, manufacturing – glass, paper, semi-conductors, arsenical pesticides andherbicides, crop desiccants). A range of arsenicals is used in industry (electro-

photography, pyrotechnics, antifouling paints, pharmaceutical substances) (Van

Elteren et al., 2002). Although the use of arsenical products (such as pesticides

and herbicides) has decreased significantly in the last few decades, As application

for wood preservation is still common. The impact of arsenical compounds on the

environment, at least locally, will remain for some years. From the various sources

of As in the environment, drinking water poses the greatest threat to human health

(Smedley and Kinniburgh, 2002). Most people are chronically exposed to low lev-

els of As, principally through water ingestion. Depending on geographical area,


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260 EWA TERLECKA

drinking waters, including natural mineral waters, may contain high inorganic ar-

senic concentrations (Van Elteren etal., 2002). Typically, the concentration of As in

unpolluted surface waters ranges 1–10 µg/L. It rises to 100–5000 µg/L on sulfide

mineralization and mining areas (Smedley et al., 1996). Extremely high concen-

tration level of As in surface water is observed from areas of thermal activity (New

Zealand – up to 8500 µg/L) and in geothermal water in Japan (up to 6400 µg/L)

(Gong et al., 2002). Permissive concentration of arsenic in surface water in Poland

at I and II classes was reduced (1.01.2004) from 0.05 to 0.01 mgAs/L. In the

Unites States, permissive concentration of arsenic in surface water must not exceed

100 ng/mL (Niedzielski, 2002). Following the increased number of evidence for

the chronic toxicological effects of As in drinking water, recommended limits are

being reduced. The International Agency for Research on Cancer and US EPA has

designated arsenic as a group A ‘known’ human carcinogen. The WHO guideline

value for As in drinking water was reduced from 50 to 10 ng/mL (daily intake of

2l). Also US EPA in January 2001 lowered the maximum contaminant level (MCL)

for total arsenic in drinking water from 50 to 10 ng/mL (EPA, 2001). In Poland, per-

missive MCL for arsenic in drinking water is 10 ng/mL (Rozporzadzenie Ministra

Zdrowia z dnia 19 listopada, 2002r), in Germany it is 40 ng/mL (Niedzielski,

2002).

Arsenic naturallyoccurs in theenvironment in inorganic as well as organic forms.

Different arsenic species present in water samples are described in Table I. In nat-

ural waters, As is mostly found in inorganic forms as trivalent arsenate (As(III))

or pentavalent arsente (As(V)). The methylated metabolities (monomethylarsonicacid (MMAA), dimethylarsinic acid (DMAA)), in which inorganic As compounds

can be methylated by microorganisms, arise under oxidizing conditions. Organic

forms may be produced in surface waters by biological activity. They are quantita-

tively unimportant but may occur where waters are impacted by industrial pollution

(Smedley and Kinniburgh,2002). Complex organic arsenic compounds (metalloids,

where As is directly connected with C atom by covalent link) such as arsenocholine

(AsC), arsenobetaine (AsB), arsenosugars and arsenic-containing lipids have been

identified in the marine environment (Niedzielski, 2002). They are very resistant

to chemical degradation (Irgolic et al., 1995). The distribution among the different

inorganic species is a function of pH, redox potential and complex formation of

other dissolved metals and ligands. The ionic interactions can also affect the reac-tivity of inorganic arsenic in natural waters. Raposo et al. (2004) described models

to estimate activity coefficient values and defined the hydrolysis thermodynamic

constant and all interaction parameters for arsenic species. They established the

basic thermodynamic model of inorganic arsenic in order to observe the arsenic

distribution in natural waters for later speciation strategies. The most important

factors controlling As speciation are redox potential (Eh) and pH. Under oxidizing

conditions at pH less than 6.9, H2AsO−

4 is dominant, while at higher pH becomes

HAsO−24 . H3AsO4 and AsO−34 may be present in extremely acidic or alkaline con-

ditions, respectively. Under reducing conditions at pH less than 9.2, the uncharged


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ARSENIC SPECIATION ANALYSIS IN WATER SAMPLES 261

TABLE I

Different arsenic species present in the water samples (Cullen and Reimer, 1989; Simon et al., 2004)

Name of species Abbreviation Structural formula

Arsenite (arsenous acid) As(III)

Arsenate (arsenic acid) As(V)

Monomethyl arsonic acid MMAA

Dimethyl arsinic acid DMAA

Dimethyl arsinoyl ethanol DMAE

Trimethyl arsine oxide TMAO

Tetramethyl arsonium ion TMAs+

Arsenobetaine AsB

Arsenicholine AsC

Arsenosugars AsS

R∗: —OH, —SO3H, —OSO3H, —OPO3HCH2CH(OH)CH2OH.


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262 EWA TERLECKA

arsenic species H3AsO3 prevail (Brookins, 1988; Yan et al., 2000). At moderate

or high redox potentials, As can be present as pentavalent oxyanions (arsenate):

H3AsO4, H2AsO−

4 , HAsO−24 , AsO

−34 . However, at more reducing conditions (acidic

and mildly alkaline) and lower redox potential, predominate the trivalent arsenic

species (H3AsO3) (Mandal et al., 2002).

In rain water, oxidation state of As present depends on the source of the pre-

cipitation. When derived from smelters, coal burning and volcanic sources may

dominate As(III). They also may be derived from landfills and soils (such as peats).

By the soils voltalization organic species in rain water may be derived. Arsenate

may be derived from marine aerosols. Reduced forms will undergo oxidation by O2in the atmosphere and react with atmospheric SO

2 or O

3 (Cullen and Reimer, 1989).

In oxic seawater, typically, As(V) dominates, though As(III), MMAA, DMAA are

also present (Moldovan et al., 1998). In open seawater, ratio of As(V)/As(III) is

typically in the range 10–100 (Andreae, 1979; Peterson and Carpenter, 1983; Pet-

tine et al., 1992). The relative proportions of As species are variable in estuarine

waters because of variable redox potential, salinity and terrestrial inputs (Abdul-

lah et al., 1995; Howard et al., 1988). However, As(V) still dominates. In the pH

range of seawater (pH around 8.2), As(V) mainly exists as HAsO−24 and H2AsO−

4 .

As(III) is present mainly as the neutral species H3AsO3. Relatively high propor-

tions of H3AsO3 are found in surface ocean waters (Cullen and Reimer, 1989;

Cutter et al., 2002). In these zones of primary productivity, increases in organic

species as a result of methylation reactions by phytoplankton have been recorded.

Their concentrations will depend on abundance and the number of species presentin the biota, and temperature (Howard et al., 1999; Moldovan et al., 1998; Riedel,

1993). In lake and river waters, As(V) is also the dominant species, though signif-

icant seasonal variations in speciation and concentration have been found (Pettine

et al., 1992; Seyler and Martin, 1990). Concentrations and relative proportions of

As(V) and As(III) vary with the changes in the input sources, redox conditions

and biological activity. During the summer months, the presence of As(III) may

increase in oxic waters by biological reduction of As(V). Higher relative propor-

tions of As(III) have been found in river stretches close to industrial inputs and

in waters with a geothermal water component (Andreae and Andreae, 1989). Pro-

portions of As(V)/As(III) are particularly variable in stratified lakes, where redox

gradients can be large and seasonally variable (Kuhn and Sigg, 1993). Proportionsof As species may also vary according to the availability of Fe and Mn oxides

(Kuhn and Sigg, 1993; Pettine et al., 1992). Organic forms of As are usually mi-

nor in surface waters. In lake waters from Ontario, Azcue and Nriagu (1995) found

As(III) concentrations of 7–75µg/L, As(V) of 19–58 µg/L and organic As of 0.01–

1.50 µg/L (DMAA, MMAA were dominant). The role of organic species may be

more important close to the sediment–water interface (Hasegawa et al., 1999). In

groundwaters, As(III) was dominant in most of the detected samples (53–98%)

(Kim et al., 2002). Ratio of As(III)/As(V) can vary as a result of variations in the

abundance of redox-active solids, the microorganisms activity and the extend of


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conversion and diffusion of O2 from the atmosphere. In arsenic-rich groundwaters

from Bangladesh, ratio As(III)/As(V) varied between 0.1 and 0.9 (typically around

0.5–0.6) (DPHE BGS/MML, 1999; Smedley et al., 2001), from inner Mongolia

the ratio was 0.6–0.9 (Smedley et al., 2001). Concentration of organic forms are

low and may be negligible in groundwaters (Chen et al., 1995). Presence of hu-

mic and lignine sulfonic acids supports the existence of As(III) in groundwaters

sample (Raessler et al., 2000). Most of the groundwater wells contained elevated

concentration of iron, manganese and sulfur (Raessler et al., 2000). In shallow

groundwaters (15 m), the

concentration of arsenic is controlled by dissolution of arsenic-rich sulfide min-

erals (Kim et al., 2002). Chronical exposure to arsenic may cause several health

effects like effects on the gastrointestinal and respiratory tracts, skin, liver, cardio-

vascular, hematopoietic and nervous systems and others (Mandal et al., 2002). As

is genotoxic to human. Chronic ingestion of high levels of inorganic As in drinking

water is associated with increased incidence of human cancer at various sites such

as skin, lung, bladder and other internal organs (Basu et al., 2001). Interests in the

determination of different species of arsenic in natural waters is caused by the fact

that toxic effects of arsenic are connected with its chemical forms and oxidation

states. Several recent reports of toxicity of arsenic carried out on animal and human

cells lines suggested that trivalent forms of arsenic are more toxic than pentavalent

forms (Hindmarsh and McCurdy, 1986; Mandal et al., 2002; United Nations Syn-

thesis Report on Arsenic in Drinking Water, 2001). Toxicity of arsenic compoundsdecreases from As(III) to six times less toxic As(V) and 100 times less toxic from

inorganic forms – methylated metabolities to organic complexes compounds of As

(Niedzielski, 2002; Russeva, 1995; United Nations Synthesis Report on Arsenic

in Drinking Water, 2001). Recently used analytical methods make possible the de-

termination of arsenic in the different oxidation states. It provides a new insight

into the linkage between exposure, metabolism and toxicity (Del Razo et al., 2001;

Mandal et al., 2001). It is necessary to determine lower concentrations of arsenic

to recognize its cumulations, transformation and toxicity to organisms. What is

required is the application of analytical methods that allow determinations at low

detection limit not only of the total concentration of an element but also its different

chemical forms and oxidation states present in the sample.

2. Arsenic Speciation Hyphenated Techniques

The elements occur in the environment in different oxidation states and various

species forms. Separation and identification of the different oxidation states of the

element is called speciation. The fundamental requirement in element speciation

is to determine each of the forms independently and without interference from

other species. An ideal speciation method provides the desired information without


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264 EWA TERLECKA

altering the original sample. In the absence of such a method, speciation relies on

a combination of analytical techniques including spectroscopic, chromatographic

and electrochemical procedures. In many instances, all forms of the element are

converted into one and next determine. Most of the speciation methods are based

on the chromatographic separation combined with a highly sensitive detection. Se-

lection of the proper separation technique depends on physico-chemical properties

such as voltality, charge or polarity of the different forms. Sometimes, combination

of two or more separation methods need to be applied. Selection of the detection

technique depends on the concentration level of the determine form present in the

sample. Also important is the type of matrix and its composition. The quantifi-

cation of species is difficult because the concentrations of different forms in the

environmental samples are very low relative to the detection limits of the available

analytical techniques. There have been many reviews of different arsenic speciation

analyses (Bednar et al., 2001; Burguera and Burguera, 1997; Guerin et al., 1999;

Irgolic, 1992; Morita and Edmonds, 1992; Simon et al., 2004; Vilano et al., 2000,

etc.). Examples of various arsenic species separation methods coupled with differ-

ent detection techniques are given in Table II. This paper presents recent research

on arsenic speciation analyses used in water samples, advantages and disadvantages

of different techniques and their improvements and modifications.

Chomatographic techniques offer excellent possibilities for separation of dif-

ferent arsenic forms in water samples, among these, the most commonly analysed

(because of their importance in environmental analyses) As(III), As(V), MMAA,

DMAA, AsC, AsB or TMAs+ (tetramethylarsonium ion – Me4As+), TMAO(trimethylarsine oxide – Me3AsO), arsenosugars and metaloproteins (Vilano et al.,

2000). The most common separation techniques used in arsenic speciation are gas

and liquid chromatography. The latter is preferred because GC requires a previ-

ous derivatisation step to produce volatile species, which is not always feasible

(organometallic compounds or complexes with bioligands). In determination of

large biological particles, capillary electrophoresis is preferred (Tomlinson et al.,

1995). HPLC is frequently used as the separation technique in water samples arsenic

speciation (Guerin et al., 1999). The most commonly used are ion-pair chromatog-

raphy (IP-HPLC), reversed-phase chromatography (RP-HPLC), ion-exchange (IE)

or ion-exclusion chromatography (SE-HPLC). Selection of applied techniques de-

pends on the size, shape and charge of separate species. However, due to the dif-ference in structure and charge of the arsenic compounds, sometimes combination

of two or more separation methods must be used (for example, IP-RP-HPLC). Ion-

pair chromatography has been developed for routine analyses of neutral and ionic

arsenic species. The resolution of these arsenic species depends on the concen-

tration of the ion-pair reagent, the flow rate, ionic strength and pH of the mobile

phase (Do et al., 2001). The optimum pH range for separating the As(III), As(V),

MMAA and DMAA is between 5.0 and 7.0. In this range, As(III) ( pKa = 9.2) is

a neutral species, which is eluted in the void volume. When the pH of the mobile

phase increases above 9.2, As(III) becomes a negatively charged species. Using a


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T A

B L E I I

E x a m

p l e s o f a r s e n i c s p e c

i e s v a r i o u s s e p a r a t i o n m e t

h o d s c o u p

l e d t o

d i f f e r e n t

d e t e c t

i o n t

e c h n i q u e s

F

l o w

N o

S e p a r a t i o n

C o l u m n

M o b i l e p h a s e

m

l / m i n

D e t e c t i o n

S p e c i e s D L

M a t r i x

R e f .

1

I P - R

P

C 1 8

B S T R u t i n 1 0 µ m

( 2 5 0 ×

4 . 6 m m ) ,

2 4 ◦ C

2 0 m M p h o s p h a t e b u f f e r ,

p H =

6 , + 0 . 1 % ( v / v ) o f

1 0 m M D D A M + 0 . 5 %

( v / v ) M e O H

0

. 8 – 2 . 0

H G - U

S N - A

F S

A s ( I I I )

D M A A

M M A A

A s ( V )

2 . 5 ∗

3 . 2

2 . 0

6 . 0

S t a n d a r d

M e s t e r e t a l .

( 1 9 9 6 )

2

I P - R

P

P B D i o n e x N S -

1 5 µ m

( 2 5 0 ×

4 . 6 m m )

5 m M T B A P +

5 %

M e O H

, p H =

7 . 3

1

. 0

H G - A

A S

A s ( I I I )

D M A A

M M A A

A s ( V )

0 . 0 7 ∗

0 . 1 5

0 . 1 0

0 . 1 0

G r o u n d w a t e r s

C h e n e t a l .

( 1 9 9 5 )

3

I P

H a m i l t o n P R P

1 r e s i n

b a s e d ( 2 5 0 ×

4 . 6

m m )

0 . 5 m M T B A p h o s p h a t e ,

4 m M p h o s p h a t e a t

p H =

9 . 0

0

. 9 0

I C P - M

S

A s ( I I I )

,

A s ( V )

M M A

,

D M A

A s B ,

A s C

n s

S u r f a c e w a t e r

G u e r i n e t a l .

( 1 9 9 9 )

4

I P - R

P

C 1 8

V y d a c 2 0 1 T P 5

µ m ( 2 5 0 ×

4 . 6 m m )

1 m M T B A P +

2 m M A A C

+

2 % M e O H

, p H =

6

1

. 0

H G - I

C P - M

S

A s ( I I I )

D M A A

M M A A

A S ( V )

0 . 0 0 2 2 ∗

0 . 0 0 3 6

0 . 0 0 5 6

0 . 0 1 0 2

S p r i n g w a t e r

G u e r i n e t a l .

( 1 9 9 9 )

5

I P

H a m i l t o n P R P

- X 1 0 0

( 2 5 0 ×

4 . 1 m m )

G r a d i e n t : 3 8 – 7

5 m M

p h o s p h a t e b u f f e r ,

p H =

5 . 7

1

. 0

H G - I

C P - M

S

A s ( I I I )

,

A s ( V )

M M A

,

D M A

0 . 1 ∗ ∗

N a t u r a l w a t e r

B e d n a r e t a l .

( 2 0 0 4 )

( C o n t i n u e d o n n e x t p a g e

)


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266 EWA TERLECKA

T A

B L E I I

( C o n t i n u e d )

F

l o w

N o

S e p a r a t i o n

C o l u m n

M o b i l e p h a s e

m

l / m i n

D e t e c t i o n

S p e c i e s D

L

M a t r i x

R e f .

6

A E x

P B B D H P o l y s p h e r

S A W ( 1 2 0 ×

4 . 6 m m )


p H =

1 0 . 3

1

. 0

M D - H

G - A

A S

D M A A

A s ( I I I )

M M A A

A s ( V )

0 . 2

∗

0 . 2

0 . 3

0 . 4

S t a n d a r d

L e e t a l .

( 1 9 9 4 )

7

A E x

S p h e r i s o r b O D

S / N H

2

m i x e d c o l u m

n 5 µ m

( 2 5 0 ×

4 . 6 m m ) ,

2 5 ◦ C

5 m M

N a H 2

P O

4 / N a 2 H P O

4 ,

p H =

5 . 0

1

. 5

M O - H

G - A

A S

A s C

A s ( I I I )

A s B

D M A A

M M A A

A s ( V )

2 . 4

∗

1 . 4

1 . 7

1 . 9

2 . 2

2 . 1

M i n e r a l

w a t e r s

M o l d o v a n

e t a l .

( 1 9 9 8 )

8

A E x

S B N u c l e o s i l S B 5 µ m

( 2 0 0 ×

4 . 0 m m )


p H =

6 . 7

5

1

H G - I

C P - A

E S

A s ( I I I )

M M A A

D M A A

A s ( V )

0 . 3

5 ∗

0 . 3

8

2 . 1

3

0 . 9

2

S p i k e d

m i n e r a l

w a t e r s

R a u r e t e t a l .

( 1 9 9 1 )

9

A E x

L C - S

A X ( 5 0 ×

4 m m )

1 2 . 5

m M m a l o n a t e ,

1 7 . 5

m M a c e t a t e ,

p H =

4 . 8

1

. 0

I C P - M

S

A s ( I I I )

A s ( V )

0 . 6

∗ ∗



( 2 0 0 4 )

1 0

A E x

S p h e r i s o r b O D

S / N H

2

m i x e d c o l u m

n 5 µ m

( 2 5 0 ×

4 . 6 m m ) ,

2 5 ◦ C

5 m M

N a H 2

P O

4 / N a 2 H P O

4 ,

p H =

5 . 0

1

. 5

I C P - M

S

A s C

A s ( I I I )

A s B

D M A

M M A

A s ( V )

0 . 1

5 ∗

0 . 2

0

0 . 2

8

0 . 0

4

0 . 0

6

0 . 0

8

M i n e r a l

w a t e r s

M o l d o v a n

e t a l .

( 1 9 9 8 )


9/26


1 1

A E x

D i o n e x

A S 7 ( 2 5 0 ×

4 . 0 m m

) D i o n e x

A G 7

G r a

d i e n t :

A , 0 . 5

m M

C H

3 C O O

C H

3 C O O N a

B , 0 . 2

5 m

M H N O

3

S t e p

fl o w

r a t e

U V

- H G

- A F S

A s (

I I I )

A s (

V )

M M A

D M A

A s B

A s C

T M A O

T M A s +

A s S

( D )

1 4 ∗ ∗ ∗

2 2 1 4 1 1 1 5 9 1 7 1 7 6

S t a n d a r

d

S i m o n e t a l .

( 2 0 0 4 )

1 2

A E x

D i o n e x

A S 7 ( 2 5 0 ×

4 . 0 m m

) D i o n e x

A G 7

G r a

d i e n t :

2 . 5 – 5 0 m

M

n i t r

i c a c

i d i n 0 . 5 %

m e t

h a n o

l

1 . 0

I C P

- M S

A s (

I I I )

,

A s (

V )

M M A

,

D M A

0 . 3 ∗ ∗



( 2 0 0 4 )

∗ A b s o l u t e

d e t e c t

i o n

l i m

i t ( n g A s

) –

t h e m

i n i m a l m a s s o f t h e e l e m e n t t h a t m

u s t

b e i n j e c t e d t o o b t a

i n a s i g n

i fi c a n t s i g n a

l .

∗ ∗ M D L ( µ g A s /

1 ) =

t ( S t u

d e n t ’ s

v a l u e

f o r a

9 9 % c o n fi

d e n c e

l e v e

l ) ×

S D ( w i t h n −

1 d e g r e e o f

f r e e

d o m

) , n =

7 .

∗ ∗ ∗ A b s o l u t e

d e t e c t

i o n

l i m

i t ( p g A

s ) –

a s t h r e e t i m e s t h e s t a n

d a r d

d e v i a t

i o n

o f n o

i s e

l e v e

l .


10/26

268 EWA TERLECKA

resin-based column and a mobile phase at pH 9.0, As(III) is retained and can be

separated from AsB, which like the zwitter ion is not retained under these condi-

tions (Gong et al., 2002). The separation of As(III), As(V), MMAA and DMAA

usually requires 8–10 min when conventional 30 cm column is used. Using a 15-cm

column or two guard columns reduces the time of resolution to 4 min (Le and Ma,

1998). The elution order is constant: As(III), DMAA, MMAA, and As(V), inde-

pendent of the various columns used. In reversed-phase chromatography, the most

authors used C18 or PRP-1 columns and isocratic conditions to separate methylated

as well as inorganic arsenic species. An advantage of using RP is the simplicity

of the technique. But limitation is that most organic modifiers are not ICP-MS

compatible. The use of ICP-MS as a detector, limits the application of RP-HPLC

due to its ability to separate a broad range of compounds with different polari-

ties simply by changing the eluent conditions (Montes-Bayon et al., 2003). The

elution order of the various species is different, even for the same authors with

slight differences in eluent compositions (Le et al., 1994; Le and Ma, 1998; Mester

et al., 1996). Complete analysis time is close to 10 min. The resolution selectivity

of the column is increased in reversed-phase chromatography when hyphenated

technique IP-RP-HPLC is used, if small amount (up to 0.005 mmol/L) of ion-pair

forms compound (tetraalkylammonium salts and alkylsulfonates are the most com-

monly used) is added to eluent (Montes-Bayon et al., 2003; Niedzielski, 2002).

That method makes possible the organic arsenic compounds (metaloproteins and

arsenosugars) selective separation in environmental samples. The advantage of RP-

IP is versatility. It permits the analysis of charged and uncharged compounds ina single chromatographic run with great reproducibility and short analysis time.

The change in resolution can be achieved by varying the ion-pairing reagents and

maintaining the MeOH:water ratio. The limitation is the possible degradation of

the silica-based columns that can occur (Montes-Bayon et al., 2003). However,

some authors (Guerin et al., 1999) point out that reversed-phase chromatography

is prone to severe matrix interferences and pH effects. They suggest that the ion-

exchange mode, although producing a poorer selectivity, is much less sensitive to

these unfavourable effects because of the higher buffering capacity of the mobile

phase. In ion-exchange chromatography, anion-exchange chromatography is the

most commonly used to analyse As(III), As(V), MMAA, DMAA, whereas cation

exchange is used to separate AsB, AsC, TMAO and TAMs

+

species (Gong et al

.,2002). Many different columns have been tested, Hamilton PRP-X100 (polymeric

anion-exchange column stable under a wide range of pH (1–13)) is the most com-

monly used. As mobile phase to separate the anionic arsenic compounds found

in drinking water, phosphate of carbonate buffer systems in isocratic or gradient

modes have been frequently used (Roig-Navarro et al., 2001; Sheppared et al.,

1992). Bednar et al. reached the detection limit DL = 0.6µg/L (ICP-MS) apply-

ing a malonate/acetate as mobile phase in isocratic separation. Using a step gradient

elution with a sodium phosphate buffer, they obtained DL from 0.1 to 0.6 µgAs/L

(HG-ICP-MS) (depending on species), in surface and groundwater samples, and


11/26


reduced the elution time of MMAA and As(V) by more than 1 min (Bednar et al.,

2004). Selection of the mobile phase containing TRIS buffer demonstrated supe-

rior separation of As(III), As(V) MMAA and DMAA in drinking water, and also

eliminated salt deposits on the ICP-MS sampling interface when compared to the

phosphate mobile phase (Milstein et al., 2002). Six arsenic species were separated

within 15 min in the order: AsC, AsB, DMAA, MMAA, As(III) and As(V) (Gong

et al., 2002). Similar to anion-pairing chromatography, AsB and As(III) co-eluted at

the void volume under the neutral pH. However, when tartaric acid was used as the

mobile phase, As(III) formed an anionic complex which could be separated from

AsB. Also, applying 30 mM ammonium carbonate as the mobile phase and increas-

ing the pH to 9.0 allowed the separation of AsB from As(III). The whole separation

process required 20 min. AsB and As(III) were also achieved with a gradient elution

using varying concentrations of ammonium phosphate as the mobile phase (Gong

et al., 2002). Alternatively, oxidation of As(III) to As(V) prior to HPLC separation

removed the interference of As(III) in the determination of AsB. The disadvantage

of ion-exchange chromatography is, as some authors indicate (Branch et al., 1994),

the separation performance of silica-based columns (SB) used in arsenic speciation.

After a number of analyses, the reproducibility and efficiency of that column may

decrease. The fast degradation of columns may partially be overcome by lowering

the mobile phase concentration, but side effects such as longer time of analysis and

some loss of resolution may occur for the retained species (Guerin et al., 1999).

Also, some authors pointed out that at sulfide concentrations >10 µM in water

sample, arsenic-sulfides confound anion-exchange resin speciation of aqueous ar-senic (Jay et al., 2004). Negatively charged As(III)-sulfide (thioarsenite) species

bind to the anion-exchange resin and might be interpreted incorrectly as As(V)

which also sorb to the resin as negatively charged. Authors suggested that reducing

waters should be tested for sulfide, and purged if necessary before anion-exchange

chromatography analysis. Capillary electrophoresis has been tested for arsenic spe-

ciation (Huang and Whang, 1998; Michalke and Schramel, 1998; Van Holderbeke

et al., 1999; Zhang et al., 2001, etc.). As(III), As(V), DMAA, MMAA, AsB and

AsC were separated by using capillary zone electrophoresis (CZE). This tech-

nique ensures high separation efficiency (Michalke and Schramel, 1998). Buffer

constituent, concentration and pH affect the separation of arsenic species. CE sep-

aration methods for arsenic speciation have been limited to simple matrix systems.Components which allow conversion to volatile derivatives were separated by us-

ing various gas chromatography modifications. Hydride generation is one of the

most widely used method for arsenic speciation due to its high sensitivity, low de-

tection limit (decimal parts of ppb) and high selectivity (Aggett and Boyes, 1989;

Braman and Foreback, 1973; Howard and Comber, 1992). Only gaseous hydrides

are introduced to the detector, thus, spectral and chemical interferences in the de-

tection system are eliminated. Hydride generation method relay on reaction of As

in suitable conditions with hydrogen, arise in reaction of reducing agent with acid.

Reaction-forming hydride AsHn at the oxidation state +m may be described as


12/26

270 EWA TERLECKA

follows (Pohl, 2004):

NaBH4 + 3H2O+HCl → H3BO3 +NaCl+ 8H

As+m + 8H → AsHn +H2 (excess)

Gaseous product, after separation from postreaction mixture is transported by

means of neutral inert carrier (argon, helium) to atomizer (AAS, AFS) or excitation

source (ICP, MIP). As(III) and As(V) give AsH3, MMAA gives monomethylar-

sine (MMA-CH3AsH2), DMAA-dimethylarsine (DMA-(CH3)2AsH). Their boil-

ing points are different (−55, 2, 35.6 ◦C) what makes possible to separate them

(Braman and Foreback, 1973; Carrero et al., 2001). The arsines formation is re-

lated to pH. In strong acid environment (pH < 1), hydride are generated from both

inorganic and MMAA, DMAA compounds. They are not generated from other

arsenoorganic compounds. In weak organic acid environment (citric, acetic, tar-

taric), the trivalent arsenic species can form hydrides, but not react compounds on

V oxidation state (Del Razo et al., 2001; Niedzielski, 2002). Hydride generation

reaction from As(V) is slower than that from As(III) and is about 10% less effective

than from As(III) (Chatterjee et al., 1995). In order to determine As(V), a two-stage

reaction is suggested that relies on reduction of As(V) to As(III) (by means of re-

duction reagents like HCl, ascorbic acid, potassium iodide, L-cysteine, thiourea or

their mixture) and next hydride generation from As(III) (Niedzielski, 2002). Pre-

liminary sample mineralization is necessary in order to decompose organic forms.Selection of the appropriate mineralization is important because HNO 3, strong ox-

idizing factor, may cause As(III) decomposition due to nitrogen oxides formation.

Interferences with reduction to As(III) are also possible (Niedzielski, 2002). There

are differences between the sensitivities obtained for the HG from inorganic and

methylated arsenic species. A significant effect on the hydride generations response

of As(III), As(V), MMAA, DMAA have the kind and concentration of the acid used

(Carrero etal., 2001). It is difficult to find such as optimum acid concentration under

which the same response can be obtained for all arsenic species. In order to obtain

the same response for all the four arsenic species under the same optimum acid

concentration, an addition of compounds containing the thiol group (L-cysteine,

thioglycerol) may be necessary. That procedure results in much lower concentra-tion of acid required for efficient arsines generation (Carrero et al., 2001; Le et al.,

1994). Additionally, the presence of L-cysteine in the reaction medium results in

the reduction of transition metals interference on the arsine generation (Carrero et

al., 2001). Hydride-generation technique makes possible almost 100% efficiency

of introducing the determined component to atomizer or spectroscopic excitation

source. It allows applying large sample volume and appropriate separation analyte

from matrix that improves detection limit. But there appear problems connected

with transportation of generation hydrides to excitation source or matrix influence

on the reaction of hydride generation (Niedzielski, 2003). Chemical interferences,


13/26


observed from the present in the matrix of transition and noble metals, resulting

in the drastic suppression of analytical signals of hydride-forming elements. Ag,

Au, Co, Cu, Ni, Fe and Pb have been considered the most serious interferences

in HG reactions. A great effort has been made to develop efficient procedures for

eliminating or reducing chemical interferences. L-cystyna, L-cysteine, L-histydine,

o-phenantroline, EDTA with tartaric acid, a mixture of tartaric acid and ascorbic

acid, KI and KCN, were examples of the complexing agents used to mask in-

terfering metals ions (Carrero et al., 2001; Pohl, 2004). The precipitation of the

hydroxides of the interfering metals or the extraction of their complexes was an-

other method of avoiding chemical interferences coming from transition-metal ions.

Pohl et al. (2004), pointed out that the increase in acid concentration or decrease

the NaBH4, successfully diminished interferences caused by transition metals. DL

of hydride-forming element are typically of 0.1 ng/mL and the precision of mea-

surements (expressed in terms of relative standard deviation) is normally better

than 5% (Pohl, 2004). Development of HG is still progressing. Recently organ-

ised surfactant-based assemblies such as micelles and vesicles were used which,

added to the sample solutions, changed the physical and chemical properties of

the HG reaction. It was found that positively charged surfactants (i.e., didodecyl-

methylammonium bromide – DDAB) enhanced the generation of As hydrides by

concentrating the reactants at the molecular level. This improved the transport and

separation efficiency of the species, resulting in better sensitivity and selectivity of

the reaction as well as increasing tolerance of transition metals ions (Pohl, 2004).

However, not all arsenic species form hydrides. Organoarsenic compounds such asAsB, AsC, Me4 As

+ or arsenosugars, require decomposition techniques like mi-

crowave or UV mineralizations (Lamble et al., 1996). HG technique coupled with

atomic absorption, atomic emission, atomic fluorescence and inductively coupled

plasma with mass spectrometry, have had wide applications in the determination

of arsenic on different oxidation states in speciation analyses of water samples.

Detection limits and sensitivity to interferences depend on detector used in the

hyphenated techniques. Determination of various forms of As in environmental

samples, because of the low concentrations and complexity of matrices, requires

high-sensitivity detection. Atomic absorption spectrometry (AAS) was used for the

speciation of arsenic in the 1980s. It is currently used for arsenic speciation, due to

its high sensitivity, selectivity and low detection limit with different separation tech-niques, andis most frequently combined with HG (DL As(III) andAs(V)


14/26

272 EWA TERLECKA

al., 1995). Maity et al. reached DL for As(III) −0.4 µg/L for groundwater samples

using HG-AAS method with citric acid for selective hydride formation of As(III)

(Maity et al., 2004). Atomic fluorescence spectrometry (AFS) is also an attractive

detection method because of its high sensitivity. Light scattering and background

interference due to the sample matrix are yet the main problems. However, using

the HG technique solved them, because only gaseous arsines are introduced to

the AFS detector. Spectral interferences caused by matrix are eliminated, which

improves the detection limit by using AFS (Featherstone et al., 2000). HG also

enhanced sensitivity for laser-induced fluorescence and laser-enhanced ionization

spectrometry (Gong et al., 2002). HG-AFS detector is simple and not expensive to

use. It allows determination of As(III), As(V), MMAA, DMAA and also AsB, AsC

after sample digestion with microwave source or UV irradiation (Slejkovec et al.,

1998, 2001) on sub-micrograms per liter detection limit in environmental samples

(Featherstone et al., 2000; Le and Ma, 1998; Mester et al., 1996; Slejkovec et al.,

1998; Vilano et al., 2000). Absolute DL of this method, using IP-RP chromatog-

raphy: As(III) = 2.5, As(V) = 4.5, MMAA = 2.0, DMAA = 2.9 ngAs (Guerin

et al., 1999; Mester et al., 1996). Simon et al. reached absolute DL (as three times

the standard deviation of noise level) for As(III) = 14, As(V) = 22, MMA = 14,

DMA = 11, AsB = 15, AsC = 9, TMAO = 17, TMAs+ = 17, AsS = 4 pgAs

(LC-UV irradiation HG-AFS method with simultaneous separation of organic and

inorganic species by combination of anion exhange and hydrophobic interactions

in a single column) (Simon et al., 2004). There are also applied techniques coupled

AES with HPLC and ICP. The spectral interferences is the most severe problemin ICP-AES method in the determination of As in environmental samples. For the

quantification of spectral interferences in the presence of multi-component envi-

ronmental matrix, Velitchkova et al. (2004) applied the Q-concept. These data were

used for quantitative line selection and calculation of the true detection limits by

the ‘best’ analysis line (DL = 0.3–0.7 µgAs/L). In order to significantly enhance

the sensitivity and reduction of interferences, HG is incorporated between HPLC

and ICP-AES (Gettar et al., 2000). Absolute DL HG-ICP-AES, using IP-RP or

anion-exchange chromatography for mineral or seawaters equals 0.35 for As(III),

0.50 for As(V), 0.38 for MMAA, 0.50 for ADMA ngAs (Guerin etal., 1999; Rauret

et al., 1991). Low DL (ng/L) is obtained in arsenic speciation in water samples us-

ing ICP-MS (inductively coupled plasma mass spectrometry). Absolute DL in therange of 0.05–2 ngAs, which were notified 10 years ago have been divided by 10.

Currently, DL = 0.1 µg/L in drinking water has become common (Guerin et al.,

1999). Shum et al. (1992) reached absolute DL lower than 1 pg, e.g. for 100 mL

of sample, DL lower than 10 ng/L per species. ICP-MS offers several advantages

like high sensitivity, multi-element capability, large range and can be combined

with different separation techniques for speciation analysis (Branch et al., 1994;

Demesmay etal., 1994; Le etal., 1994; Morita and Edmonds, 1992). Some difficul-

ties arise from the coupling of ICP-MS with separation techniques because many

of them require using a high ionic buffer strength (when complex sample matrix).


15/26


High salt concentrations can cause signal suppression due to increased space-charge

effects which distract the ion beam (Larsen, 1998). Sample pre-treatment, changing

argon flow rates, modifying interface configurations and voltages post-column di-

lution can solve problems partially (Rosen and Hieftje, 2004). Hyphenated method

HPLC-ICP-MS is now considered the most-effective technique in arsenic specia-

tion in many arsenic research laboratories (Bednar et al., 2004; Guerin et al., 1999;

Klaue and Blum, 1999; Le et al., 1998; Milstein et al., 2002; Moldovan et al.,

1998; Saeki et al., 2000; Taniguchi et al., 1999, etc.) Additional HG reduces the

detection limit of instrument (around 1 ng/L) compared to conventional ICP-MS,

and prevents the spectral interferences which may occur due to formation of ArCI

ions.

Determination of arsenic species in seawater provides some difficulties. Since

total arsenic concentration in seawater is low (about 1–2 ng/mL) (Andreae, 1979;

Cullen and Reimer, 1989), the analytical method for arsenic speciation requires

the DL below ng/mL. In the case of direct analysis, a large amount of rich matrix,

the highly saline samples deteriorates separation process and also the chloride ions

cause spectroscopic interference of ArCl on As measurement by ICP-MS (Larsen,

1998; Nakazato et al., 2002). The extensive peak of ArCI overlapped peaks of ar-

senic species measurement by ICP-MS. Pre-treatment forremoving thematrixor the

dilution of the sample is necessary (Nakazato et al., 2002). These operations, how-

ever, decrease the concentration of arsenic species below the DL for most ICP-MS

systems. The pre-treatment also may alter the original sample composition (Cabon

and Cabon, 2000). However, it was reported that this interference was efficientlyeliminated by collision of ArCl molecules with helium introduced prior to mass

spectrometer in reaction cell (Nakazato et al., 2002). These analytical procedures

enabled the highly sensitive determination of As(V), As(III), MMAA and DMAA

at pg/mL level (Cabon and Cabon, 2000; Featherstone et al., 2000; Hasegawa

et al., 1999) in seawater samples (even a large volume (200 mL)) by ion-exclusion

chromatography (polystyrene resin, dilute nitric acid at pH = 2.0 as the eluent)

combined with HG-ICP-MS (Nakazato et al., 2002). The method is easy to oper-

ate and no sample pre-treatment is needed. The concentration of arsenic species in

some mineral waters is usually higher than in other natural waters (Moldovan et al.,

1998). In mineral waters, As is usually present in toxic inorganic forms and their

determination is mandatory. Using IP-RP or AEx chromatography and ICP-MS,for mineral or spring waters determinations, absolute DL equals 0.0022 for As(III),

0.0040 for As(V), 0.0056 for MMAA, 0.0036 for DMAA, 0.006 for AsB, 0.012 for

AsC ngAs (Guerin et al., 1999). HPLC-HG-AAS or HPLC-ICP-MS are most com-

monly used. The main problems of those hyphenated techniques are associated with

chromatographic separation of species, polyatomic interference in ICP-MS and the

different efficiency of hydride generation for various arsenic species. Currently, US

EPA approved ICP-MS, ICP-AES and AAS with HG for monitoring of As levels in

water samples (Code of Federal Regulations, 40 CFR 141.23). The HPLC-ICP-MS

method is considered the best alternative for monitoring arsenic at trace levels. The


16/26

274 EWA TERLECKA

limitation of HPLC-ICP-MS is that it is sometimes unable to identify the species of

a particular element and further information is needed. ES-MS (electrospray mass

spectrometry) has become the most common method to obtain complementary in-

formation in order to identify unknown peaks (McSheehy et al., 2001; Pedersen

and Francesconi, 2000; Pohl and Szpunar, 2001). ES-MS, or also used ES-MS/MS

(electrospray ionization tandem mass spectrometry), can provide structural and

molecular verification of compounds (Montes-Bayon et al., 2003). DL for HPLC-

ES-MS ranged from 0.2 to 1.2 ng/mL (Gong et al., 2002). The disadvantage of

ES-MS is poor detection limit compared to ICP-MS. Some authors pointed out that

preconcentration of chromatographic fractions before analysis by ES-MS is needed

(Montes-Bayonetal., 2003).Otherproblem is connected with the suppression of the

analyte signal by complex matrices (high concentrations of salts in HPLC buffers of

CE electrolytes). Ion-spray (pneumatically assisted ES) can be used, which enables

a wider range of solvent composition (Montes-Bayon et al., 2003). The most com-

mon mass analyzer used in conjunction with ionization sources (ICP and ES) has

been the quadrupole mass filter. In current research, increased importance of other

types of mass analyzers such as ion-trap and sector-field is shown. Use of these

mass analyzers improve resolution and make possible simultaneous ion detections

(Montes-Bayon et al., 2003). Also several electrochemical techniques have been

described for arsenic speciation analyses in water like polarography and voltametry.

In determination of the groundwater samples using square-wave anodic stripping

voltametry, DL for As(III) could reach 0.05 ng/mL (Dasgupta et al., 2002). Spe-

ciation method based on differential pulse cathodic stripping voltametry (DPCSV)with DL= 0.5µg/L in natural water samples, suitable for use in the field described

He et al. (2004). To improve the peak shape (sharp and symmetric) and the method

sensitivity, Cu(II) and Se(IV) were used together to form intermetallic arsenic com-

pounds (Cu x Se yAs z) on the hanging mercury drop electrodes (HMDE) during the

deposition procedure. Authors adopted sodium meta-bisulfite/sodium thiosulfate in

sulfuric acid reagent, which feature good stability, as a reducing reagent for As(V)

determination. The electrochemical methods are relatively simple and inexpensive

with superb sensitivity. Ion chromatography with conductivity detection has been

used for the determination of arsenate in the presence of other ions (Hemmings

and Jones, 1991; Li et al., 1995). A genetically engineered bacterium that produces

the enzyme β

-galactosidase in response to As(III) has been applied to arsenicdetection (Scott et al., 1997). The activity of this enzyme was electrochemically

monitored. The progress in analytical arsenic speciation covering not only the tech-

niques for species separation, identification and quantification, but also methods

for extracting and stabilizing the arsenic species from the matrix. The procedures

used for sample handling and storage are very important and must be considered

because of losses forms from the sample solution or their conversion from one

to another (Gong et al., 2002). The sample handling results in the oxidation of

As(III) to As(V) (Kim, 2001; Raessler et al., 1998; Roig-Navarro et al., 2001). The

oxidation of As(III) in conjunction with the photochemical reduction of Fe(II) (in


17/26


iron-reach waters) take place according to the following reaction (Emett and Khoe,

2001):

2 Fe+3 +H3AsO3 +H2O → 2 Fe+2+H3AsO4 +2H

+

Arsenic redox preservation can be achieved by filtering the sample and adding

reagents (HCI, H2SO4, EDTA) that prevent oxidation and precipitation of dissolved

Fe and Mn (Gallagher et al., 2001; McCleskey et al., 2004). Immediate separation

of As(III) and As(V) after water sample collection is suggested (Kim, 2001; Le

et al., 2000). Stability studies in spiked surface waters maintained at 4 ◦C without

acidification showed oxidation of As(III) to As(V), but there were not any changes

for the other species during 15 days (Roig-Navarro et al., 2001). The samples con-

taining concentrations of As(III) and As(V) at 0.5 or 1 mg/L stored at 4 ◦C were

stable for 21 days and some transformation was showed after 29 days of storage

(Jokai et al., 1998). Methylarsenicals are more stable than inorganic arsenic in

water samples (Gong et al., 2002; Jokai et al., 1998; Lindemann et al., 2004; Pala-

cios et al., 1997). The concentrations of DMAA, MMAA and AsB were constant

(Lindemann et al., 2004), or at concentration of 0.01–10 ng/mL were stable for 5–6

months at room temperature (Jokai et al., 1998). Some studies recommend freezing

aqueous samples at −20 ◦C (Lindemann et al., 2004; Palacios et al., 1997). Some

authors use ascorbic acid and HCL addition for preservation (Gong et al., 2002).

HCI works well as preservative for arsenic redox species for a wide range of natural

waters samples and is preferred when HG-AAS is used for determination becausethe sample matrix is similar to the HCI carrier solution. For HPLC-ICP-MS appli-

cations, EDTA is preferred because samples preserved with HCI interfere in the

determination of As due to the 40Ar35Cl+ molecular interference on monoistopic75As+ (McCleskey et al., 2004). Addition of EDTA (1.25 mM) and storage in the

dark, can reduce the transformation among the arsenic compounds in rain water

(Huang and IIgen, 2004). Authors suggest to avoid using methanol for extraction

(pre-concentration of methanol–water solution could results in potential overesti-

mation of arsenic compounds concentrations (As(III) and MMAA). Obtaining reli-

able information about the presence of different species of arsenic in environmental

samples requires control of quality of the entire analytical method as well as the

intermediate steps (sample pre-treatment procedures, extraction, pre-concentration

and separation of species). Different methods for arsenic speciation were validated

by analysing various reference materials (US EPA water reference material, Na-

tional Research Council of Canada (NRCC) river water reference material SLRS-1

(Pohl and Prusisz, 2004), NIST water standard reference materials SRM 1640 (He

et al., 2004), SRM, 1643; Le et al., 2000, etc.). However, assessment of the quality

assurance is usually based on spiking experiments (reference materials allow verifi-

cation of the accuracy only for total As content). Another way of validating arsenic

speciation methods involves inter-laboratory comparisons of the results obtained

using independent instrumentation and procedures.


18/26

276 EWA TERLECKA

3. Conclusion

Determination of the different chemical forms of arsenic in natural waters is im-

portant because of their various toxicological effects. The techniques used for the

detection of arsenic species in environmental samples should be sensitive and se-

lective. Hyphenated techniques involving a highly efficient separation and a highly

sensitive detection have become the techniques of choice. Methods based on high-

performance liquid chromatography separation with inductively coupled plasma

mass spectrometry, hydride generation atomic spectrometry and electrospray mass

spectrometry detection have been the most useful for arsenic speciation in environ-

mental samples. Currently, speciation techniques proceed in possibilities of deter-

mination of metal complexes with bioligands. The molecular techniques, where it

is possible to establish the structure of separating compounds, become increasingly

important. The inherent advantages and disadvantages of each method can be used

to select the most appropriate method based on the type of sample matrix to be

analyzed and the arsenic species and concentration levels to be determined. There

is a need to develop stabilizing methods for arsenic species in water samples to

obtain reliable results. Limited availability of standards and reference materials for

various chemical forms of analyte still pose difficulty in speciation analyses of the

environmental samples (Niedzielski, 2002).

References

Abdullah, M. I., Shiyu, Z. and Mosgren, K.: 1995, ‘Arsenic and selenium species in the oxic and

anoxic waters of the Oslofjord, Norway’, Mar. Pollut. Bull. 31, 116–126.

Aggett, J. and Boyes, G.: 1989, ‘Investigation of the contribution of metal ion enhancement of the

rate of hydrolysis of sodium tetraborate to interferences in the determination of As(III) by hydride

generation atomic absorption spectrometry’, Analyst 114, 1159–1161.

Ali, I. and Aboul-Enein, H.: 2002, ‘Speciation of arsenic and chromium metal ions by reversed phase

high performance liquid chromatography’, Chemosphere 48(3), 275–278.

Andreae, M. O.: 1979, ‘Arsenic speciation in seawater and interstitial waters: The influence of

biological–chemical interactions on the chemistry of a trace element’, Limnol. Oceanogr. 24,

440–452.

Andreae, M. O. and Andreae, T. W.: 1989, ‘Dissolved arsenic species in the Schelde estuary and

watershed’, Belgium Estuar. Coast. Shelf Sci. 29, 421–433.

Azcue, J. M. andNriagu, J. O.: 1995, ‘Impactof abandoned mine tailings on thearsenic concentrationsin Moira Lake, Ontario’, J. Geochem. Explor. 52, 81–89.

Ballin, U., Kruse, R. and Ruessel, H. A.: 1994, ‘Determination of total arsenic and speciation of

arsenobetaine in marine fish by means of reaction-headspace gas chromatography utilising flame

ionisation detection and element specific spectrophotometric determination’, Fresenius J. Anal.

Chem. 350, 54–61.

Basu, A., Mahata, J., Gupta, S. and Giri, A. K.: 2001, ‘Genetic toxicology of a paradoxical human

carcinogen, arsenic: A review’, Mutat. Res. 488(2), 171–194.

Bednar, A. J., Garbarino, J. R., Burkhardt, M. R., Ranville, J. F. and Wildeman, T. R.: 2004, ‘Field

and laboratory arsenic speciation methods and their application to natural-water analysis’, Water

Res. 38, 355–364.


19/26


Braman, R. S. and Foreback, C. C.: 1973, ‘Methylated forms of arsenic in the environment’, Science

182(118), 1247–1249.

Branch, S., Ebdon, L. and O’Neill, P.: 1994, ‘Determination of arsenic species in fish by directly

coupled high performance liquid chromatography-induced coupled plasma mass spectrometry’,

J. Anal. Atom. Spectrom. 9, 33–37.

Brookins, D. G., 1988, Eh–pH Diagrams for Geochemistry, Springer-Verlag, Berlin.

Burguera, M. and Burguera, J. L.: 1997, ‘Analytical methodology for speciation of arsenic in envi-

ronmental and biological samples’, Talanta 44, 1581–1604.

Cabon, J. Y. and Cabon, N.: 2000, ‘Speciation of major arsenic species in seawater by flow injection

hydride generation atomic absorption spectometry’, Fresenius J. Anal. Chem. 368(5), 484–489.

Capelo, J. L., Lavilla, I. and Bendicho, C.: 2001, ‘Utlrasonic extraction followed by sonolysis–

ozonolysis as a sample pretreatment method for determination of reactive arsenic toward sodium

tetrahydroborate by flow-injection-hydride generation AAS’, Anal. Chem. 73, 3732–3736.Carrero, P., Malave, A., Burguera, J. L., Burguera, M. and Rondon, C.: 2001, ‘Determination of

various arsenic species by flow injection hydride generatuin atomic absorption spectrometry:

Investigation of the effects of the acid concentration of different reaction on the generation of

arsines’, Anal. Chim. Acta 438(1–2), 195–204.

Chatterjee, A., Das, D., Mandal, B. K., Chowdhury, T. R., Samanta, G. and Chakraborty, D.: 1995,

‘Arsenic in groundwater in six districts of West Bengal, India: The biggest arsenic calamity in the

world. Part 1. Arsenic species in drinking water and urine of the affected people’, Analyst 120,

643–656.

Chausseau, M., Roussel, C., Gilon, N. and Mermet, J. M.: 2000, ‘Optimization of HPLC-ICP-AES

for the determination of arsenic species’, Fresenius’ J. Anal. Chem. 366(5), 476–480.

Chen, S. L., Yeh, S. J., Yang, M. H. and Lin, T. H.: 1995, ‘Trace element concentration and arsenic

speciation in the well water of a Taiwan area with endemic Blackfoot disease’, Biol. Trace Elem.

Res. 48, 263–274.

Code of Federal Regulations, 40 CFR 141.23. Available from: http://www.epa.gov/safe-water/ars/monovr.html

Cullen, W. R. and Reimer, K. J.: 1989, ‘Arsenic speciation in the environment’, Chem. Rev. 89,

713–764.

Cutter, G. A., Cutter, L. S., Featherstone, A. M. and Lohrenz, S. E.: 2001, ‘Antimony and arsenic

biogeochemistry in the western Atlantic Ocean’, Deep-Sea Res. Part II – Topical Stud. Oceanog.

48, 2895–2915.

Del Razo, L. M., Styblo, M., Cullen, W. R. and Thomas, D. J.: 2001, ‘Determination of triva-

lent methylated arsenicals in biological matrices’, Toxicol. Appl. Pharmacol. 174(3), 282–

293.

Demesmay, C., Olle, M. and Porthault, M.: 1994, ‘Arsenic speciation by coupling high performance

liquid chromatography with induced coupled plasma mass spectrometry’, Fresenius J. Anal.

Chem. 348, 205–210.

Dasgupta, P. K., Hyang, H., Zhang, G. and Cobb, G.: 2002, ‘Photometricmeasurement of trace As(III)

and As(V) in drinking water’, Talanta 58, 153-164.

Do, B., Robinet, S., Pradeau, D. and Guyon, F.: 2001, ‘Speciation of arsenic and selenium compounds

by ion-pair reversed-phase chromatigraphy with electrothermic atomic absorption spectrometry’,

J. Chromatogr. A. 918(1), 87–98.

Dojlido, J. and Świetlik, R.: 1998, ‘Analiza śladowa wody’, in: A. Kabata-Pendias and B. Szteke

(eds), Quality Problems in Trace Analysis in Environmental Studies, Warszawa, Poland, pp. 215–

238.

DPHE-BGS/MML: 1999, Groundwater Studies for Arsenic Contamination in Bangladesh. Phase I:

Rapid Investigation Phase. BGS/MML Technical Report to Department for International

Development , UK, 6 volumes.


20/26

278 EWA TERLECKA

Emett, M. T. and Khoe, G. H.: 2001, ‘Photochemical oxidation of arsenic by oxygen and iron in acidic

solutions’, Water Res. 35, 649–656.

EPA.: 2001, ‘National Primary Drinking Water Regulations; arsenic and clarifications to compliance

and newsource contaminants monitoring’, Fed. Register 66, 6975–7066.

Featherstone, A. M., Boult, P. R., O’Grady, B. V. and Butler, E. C. V.: 2000, ‘A shipboard method for

arsenic speciation using semi-automated hydride generation atomic fluorescence spectroscopy’,

Anal. Chim. Acta 409, 215–226.

Feeney, R. and Kounaves, S. P.: 2000, ‘On site analysis of arsenic in groundwater using a microfab-

ricated gold ultramicroelectrode array’, Anal. Chem. 72(10), 2222–2228.

Gallagher, P. A., Schwegel, C. A., Wei, X. and Creed, J. T.: 2001, ‘Speciation and preservation of

inorganicarsenic in drinking watersourcesusing EDTA with IC separationand ICP-MS detection’,

J. Environ. Monit. 3(4), 371–376.

Gallagher, P. A., Shoemaker, J. A., Wei, X., Brockho-Schwegel, C. A. and Creed, J. T.: 2001,‘Extraction and detection of arsenicals in seaweed via accelerated solvent extraction with ion-

chromatographic separation and ICP-MS detection’, Fresenius J. Anal. Chem. 369, 71–80.

Gettar, R. T., Garavaglia, R. N., Gautier, E. A. and Batistoni, D. A.: 2000, ‘Determination of inorganic

andorganic anionic arsenic species in water by ionchromatographycoupled to hydride generation-

inductively coupled plasma atomic emission spectrometry’, J. Chromatogr. A 884(1–2), 211–221.

Gomez-Ariza, J. L., Sanchez-Rodas, D. and Giraldez, I.: 1998, ‘Selective extraction of iron oxide

associated arsenic species from sediments for speciation with coupled HPLC-HG-AAS’, J. Anal.

Atom. Spectrom. 13, 1375–1379.

Gong, Z., Lu X., Ma, M., Watt, C. and Le, X. C.: 2002, August 16, ‘Arsenic speciation analysis’,

Talanta 58(1), 77–96.

Guerin, T., Astruc, A. and Astruc, M.: 1999, ‘Speciation of arsenic and selenium compounds by

HPLC hyphenated to specific detectors: A review of the main separation techniques’, Talanta

50(1), 1–24.

Hall, G. E. M., Pelchat, J. C. and Gauthier, G.: 1999, ‘Stability of inorganic arsenic(III)and arsenic(V)in water samples’, J. Anal. Atom. Spectrom. 14, 205–213.

Hasegawa, H., Matsui, M., Okamura, S., Hojo, M., Iwasaki, N. and Sohrin, Y.: 1999, ‘Arsenic speci-

ation including ‘hidden’ arsenic in natural waters’, Appl. Organometal. Chem. 13, 113–119.

He, B., Jiang, G. B. and Xu, X.: 2000, ‘Arsenic speciation based on ion exchange high-performance

liquid chromatography hyphenated with hydride generation atomic fluorescence and on-line UV

photo oxidation’, Fresenius J. Anal. Chem. 368(8), 803–808.

He, Y., Zheng, Y., Ramnaraine, M. and Locke, D.: 2004, ‘Differential pulse cathodic stripping voltam-

metric speciation of trace level inorganic arsenic compounds in natural water samples’, Anal.

Chim. Acta 511, 55–61.

Hemmings, M. J. and Jones, E. A.: 1991, ‘The speciation of arsenic(V) and arsenic(III) by ion

exchange chromatography in solutions containing iron and sulphuric acid’, Talanta 38, 151–

156.

Hindmarsh, J. T. and McCurdy, R. F.: 1986, ‘Clinical and environmental aspects of arsenic toxicity’,

Crit. Rev. Clin. Lab. Sci. 23(4) 315–347.

Howard, A. G., Apte, S. C., Comber, S. D. W. and Morris, R. J.: 1988, ‘Biogeochemical control of

the summer distribution and speciation of arsenic in the Tamar estuary’, Estuar. Coast. Shelf Sci.

27, 427–443.

Howard, A. G. and Comber, S. D. W.: 1992, ‘Hydride trapping techniques for the speciation of

arsenic’, Mikrochim. Acta 109, 27–33.

Howard, A. G., Hunt, L. E. and Salou, C.: 1999, ‘Evidence supporting the presence of dissolved

dimethylarsinate in the marine environment’, Appl. Organometal. Chem. 13, 39–46.

Huang, J.-H. and Ilgen, G.: 2004, ‘Blank values, adsorption, pre-concentration, and sample preserva-

tion for arsenic speciation of environmental water samples’, Anal. Chim. Acta 512, 1–10.


21/26


Huang, Y. M. and Whang, C. W.: 1998, ‘Capillary electrophoresis of arsenic compounds with indirect

fluorescence detection’, Electrophoresis 19(12), 2140–2144.

Inoue, Y., Kawabata, K., Takahashi, H. and Endo, G.: 1994, ‘Determination of arsenic compounds

using inductively coupled plasma mass spectrometry with ion chromatography’, J. Chromatogr.

675A, 149–154.

Irgolic, K. J.: 1992, ‘Arsenic’, in : M. Stoeppler (ed), Hazardous Metals in the Environment , Elsevier,

Amsterdam, pp. 288–350.

Irgolic, K. J., Greschonig, H. and Howard, A. G.: 1995, ‘Arsenic’ in: A. Townshend (ed), The Ency-

clopedia of Analytical Science, Academic Press, pp. 168–184.

Jain, C. K. and Ali, I.: 2000, ‘Arsenic: Occurrence, toxicity and speciation techniques’, Water Res.

34(17), 4304–4312.

Jay, J. A., Blute, N. K., Hemond, H. F. and Durant, J. L.: 2004, ‘Arsenic-sulfides confound anion

exchange resin speciation of aqueous arsenic’, Water Res. 38, 1155–1158.Jokai, Z., Hegoczki, J. and Fodor, P.: 1998, ‘Stability and optimization of extraction of four arsenic

species’, Microchem. J. 59(1), 117–124.

Jurica, L., Manova, A., Dzurov, J., Beinrohr, E. and Broekaert, J. A. C.: 2000, ‘Calibrationless flow-

through stripping coulometric determination of arsenic(III) and totalarsenic in contaminatedwater

samples after microwave assisted reduction of arsenic(V)’, Fresenius J. Anal. Chem. 366(3), 260–

266.

Kabata-Pendias, A. and Szteke, B.: 1998, ‘Quality Problems in Trace Analysis in Environmental

Studies’, Wydawnictwa Edukacyjne, Warsaw, Poland.

Klaue, B. and Blum, J. D.: 1999, ‘Trace analyses of arsenic in drinking water by inductively cou-

pled plasma mass spectrometry: High versus hydride generation’, Anal. Chem. 71(7) 1408–

1414.

Kim, M. J.:2001,‘Separationof inorganicarsenic species in groundwater using ionexchangemethod’,

Bull. Environ. Contam. Toxicol. 67(1), 46–51.

Kim, M. J.,Nriagu, J. andHaack,S.: 2002, ‘Arsenic species and chemistryin groundwater of southeastMichigan’, Environ. Pollut. 120, 379–390.

Kuhn, A. and Sigg, L.: 1993, ‘Arsenic cycling in eutrophic Lake Greifen, Switzerland – Infuence of

seasonal redox processes’, Limnol. Oceanogr. 38, 1052–1059.

Lamble, K. J., Sperling, M. and Welz, B.: 1996, ‘Arsenic speciation in biological samples by on-

line high performance liquid chromatography-microwave digestion-hydride generation-atomic

absorption spectrometry’, Anal. Chim. Acta 334(3), 261–270.

Larsen, E. H.: 1998, ‘Method optimization and quality assurance in speciation analysis using high

performance liquid chromatography with detection by inductively coupled plasma mass spec-

trometry’, Spectrochim. Acta. Part B: Atom. Spectro. 53(2), 253.

Le, X. C., Cullen,W. R. and Reimer, K. J.: 1994, ‘Speciation of arsenic compounds by HPLCwith hy-

dride generation atomic absorption spectrometry and induced coupled plasma mass spectrometry

detection’, Talanta 41, 495–502.

Le, X. C., Li, X. F., Lai, V., Ma, M., Yalcin, S. and Feldmann, J.: 1998, ‘Simultaneous specia-

tion of selenium and arsenic using elevated temperature liquid chromatography separation with

inductively coupled plasma mass spectrometry detection’, Spectrochim. Acta B 53(6–8), 899–

909.

Le, X. C. and Ma, M.: 1998, ‘Short-column liquid chromatography with hydride generation atomic

fluorescence detection for the speciation of arsenic’, Anal. Chem. 70(9), 1926–1933.

Le, X. C., Yalcin, S. and Ma, M.: 2000, ‘Speciation of submicrogram per liter levels of arsenic in

water on-site species separation integrated with sample collection’, Environ. Sci. Technol. 34,

2342–2347.

Li, Z. L., Mou, S., Ni, Z. and Riviello, J. M.: 1995, ‘Sequential determination of arsenic and arsenate

by ion chromatography’, Anal. Chim. Acta 307, 79–87.


22/26

280 EWA TERLECKA

Lindemann, T., Prange, A., Dannecker, W. and Neidhart. B.: 2000, ‘Stability studies of arsenic,

selenium, antimony and tellurium species in water, urine, fish and soil extracts using HPLC/ICP-

MS’, Fresenius J. Anal. Chem. 368(2–3), 214–220.

Lobiniski, R. and Adams, F.: 1993, ‘Recent advances in speciation analysis by capillary gas chro-

matography microwave induced plasma atomic emission spectrometry’, Trends Anal. Chem. 12,

41–49.

Lopez, M. A., Gomez, M. M., Placio, M. A. and Camara, C.: 1993, ‘Determination of six arsenic

species by high performance liquid chromatography-hydride generation atomic absorption spec-

trometry with on-line thermoxidation’, Fresenius J. Anal. Chem. 346, 643–647.

Maity, S.,Chakravarty, S.,Thakur,P., Gupta,K. K.,Bhattacharjee,S. andRoy, B. C.:2004,‘Evaluation

and standardisation of a simple HG-AAS method for rapid speciation of As(III) and As(V) in

some contaminated groundwater samples of West Bengal, India’, Chemosphere 54, 1199–1206.

Mandal, B. K., Kazno, T. and Suzuki K. T.: 2002, ‘Arsenic round the world: A review’, Talanta 58,201–235.

Mandal, B. K., Ogra, Y. and Suzuki, K. T.: 2001, ‘Identification of dimethylarsinous and monomethy-

larsonous acids in human urine of the arsenic-affected areas in West Bengal, India’, Chem. Res.

Toxicol. 14, 371–375.

Martinez-Bravo, Y., Roig-Navarro, A. F., Lopez, F. J. and Hernandez, F.: 2001, ‘Multielemental

determination of arsenic, selenium and chromium(IV) species in water by high-performance

liquid chromatography inductively coupled plasma mass spectrometry’, J. Chromatogr. A 926(2),

265–724.

Martin, I., Lopez-Gonzalvez, M. A., Gomez, M.,Camara, C. and Palacios, M. A.:1995, ‘Evaluation of

high-performance liquid chromatography for the separation and determination of arsenic species

by on-line high-performance liquid chromatographic-hydride generation-atomic absorption spec-

trometry’, J. Chromatogr. B: Biomed. Appl. 666(1), 101–109.

McCleskey, R. B., Nordstrom, D. K. and Maest, A. S.: 2004, ‘Preservation of water samples for

arsenic(III/V) determinations: An evaluation of literature and new analytical results’, Appl.Geochem. 19, 995–1009.

McSheehy, S., Pohl, R., Lobinski, R. and Szpunar, J.: 2001, ‘Complementarity of multidimensional

HPLC-ICP-MS and electrospray MS-MS for speciation analysis of arsenic in algae’, Anal. Chim.

Acta 440, 3–15.

McSheehy, S., Pohl, P., Lobinski, R. and Szpunar, J.: 2001, ‘Investigation of arsenic speciation in

oyster test reference material by multidimensional HPLC-ICP-MS and electrospray tandem mass

spectrometry (ES-MS-MS)’, Analyst 126(7), 1055–1062.

Mester, Z., Woller, A. and Fodor, P.: 1996, ‘Determination of arsenic species by high-

performance liquid chromatography-hydride generation-(ultrasonic nebulizer)-atomic fluores-

cence spectrometry’, Microchem. J. 54(3), 184–194.

Michalke, B. and Schra

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