Arsenic, determination ICPES

Gaseous sample introduction into an ICP-MS presents different problems. Owing to its extremely sensitive nature, Dean et al. [13] introduced the sample as the gaseous hydride by a flow-injection approach. This was reasonably effective because lower volumes of samples and reagents were in use. They utibzed nitric acid as a carrier stream to prevent the formation of argon chloride species in the plasma. Argon chloride has the same mass as arsenic which is mono-isotopic, and this severely bmits arsenic determination. An additional problem was that the sensitivity was extremely dependent on the purity of reagents. 

Early colorimetric methods for arsenic analysis used the reaction of arsine gas with either mercuric bromide captured on filter paper to produce a yellow-brown stain (Gutzeit method) or with silver diethyl dithiocarbamate (SDDC) to produce a red dye. The SDDC method is still widely used in developing countries. The molybdate blue spectrophotometric method that is widely used for phosphate determination can be used for As(V), but the correction for P interference is difficult. Methods based on atomic absorption spectrometry (AAS) linked to hydride generation (HG) or a graphite furnace (GF) have become widely used. Other sensitive and specihc arsenic detectors (e.g., AFS, ICP-MS, and ICP-AES) are becoming increasingly available. HG-AES, in particular, is now widely used for routine arsenic determinations because of its sensitivity, reliability, and relatively low capital cost. 

Some of the many uses for ICP-MS include analysis of environmental samples for ppb levels of trace metals and nonmetals, the analysis of body fluids for elemental toxins such as lead and arsenic, determination of trace elements in geological samples, metals and alloys,... 

Menendez Garcia et al.[50] combined on-line liquid-liquid extraction separation with hydride generation gas-liquid separation for the determination of arsenic with ICPES. Arsenic in the aqueous sample is extracted as ASI3 into xylene which is continuously mixed on-line with sodium borohydride in dimethylformamide and acetic acid solutions. Arsine is generated in the organic phase and separated in a gas-liquid separator which prevents most of the xylene vapour from entering the plasma. The method was used to improve the sensitivity and to remove interferences from transition metals in the determination of low levels of arsenic in white metal, cast iron, cupro-nickel etc.. 

Byrne, S., Amarasiriwardena, D., Bandak, B., Bartkus, L., Kane, J., Jones, J., Yanez, J., Arriaza, B., Cornejo, L. (2010) Were Chinchorros exposed to arsenic Arsenic determination in Chinchorro mummies hair by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). Microchemical Journal, 94,28-35. 

Diaz-Somoano, M., and Martinez-Tarazona, M. R. (1999). Application of ICP-MS to arsenic determination in solid samples containing si ic2i.J. Anal. At. Spectrom. 14(9), 1439. 

Berman et al. [735] have shown that if a seawater sample is subjected to 20-fold preconcentration by one of the above techniques, then reliable analysis can be performed by ICP-AES (i.e., concentration of the element in seawater is more than five times the detection limit of the method) for iron, manganese, zinc, copper, and nickel. Lead, cobalt, cadmium, chromium, and arsenic are below the detection limit and cannot be determined reliably by ICP-AES. These latter elements would need at least a hundredfold preconcentration before they could be reliably determined. 

Alves et al. [744] determined vanadium, nickel, and arsenic in seawater in the 10-20 000 ppt range using flow injection cryogenic desolvation ICP-MS. 

Stroh and Voellkopf [746] utilised flow injection analysis coupled to ICP-MS to determine down to 0.6 ppt of antimony, arsenic, and mercury in seawater. 

The determination of the total concentrations of metal ions and arsenic in the water samples and in the eluates of solid materials were carried out using ICP-AES (Spectroflame, SPECTRO A.I.) with pneumatic nebulization (cross flow). Anion (S042, Cl ) determinations were done using an ion chromatographic device with IonPac AS12A/AG12A column and a conductivity detector. 

For the determination of organotin compounds (tributyltin, triphenyltin, triethyltin, and tetra-ethyltin) a MAE is proposed before the normal phase (NP) HPLC/UV analysis [35], In organotin and arsenic speciation studies, hydride generation is the most popular derivatization method, combined with atomic absorption and fluorescence spectroscopy or ICP techniques [25,36], Both atmospheric pressure chemical ionization (APCI)-MS and electrospray ionization ESI-MS are employed in the determination of butyltin, phenyltin, triphenyltin, and tributyltin in waters and sediments [37], A micro LC/ESI-ion trap MS method has been recently chosen as the official EPA (Environmental Protection Agency) method (8323) [38] it permits the determination of mono-, di-, and tri- butyltin, and mono-, di-, and tri-phenyltin at concentration levels of a subnanogram per liter and has been successfully applied in the analysis of freshwaters and fish [39], Tributyltin in waters has been also quantified through an automated sensitive SPME LC/ESI-MS method [40],... 

Importantly, neither arsenobetaine nor arsenocholine forms an arsine on treatment with borohydride solutions. Consequently, arsenobetaine and arsenocholine may remain undetected in samples, seawater for example, when arsines are generated and determined in an arsenic speciation analysis. The technique HPLC/ICP-MS is most suitable for the analysis of these (non-arsine-forming) compounds (49). Use of the highly sensitive ICP-MS detector allows application of small quantities of material to the chromatography column, thereby obviating possible sample matrix effects previously observed for arsenobetaine (50). 

Fig. 3. Typical separation of four arsenosugars and DMA by HPLC/ICP-MS using an ODS reversed-phase column at pH 3.2 under conditions described in Ref. 60. The sensitivity and specificity of the detector allows the determination of arsenosugars and other arsenic compounds to be conducted on dilute aqueous extracts of the marine samples.

Thomas and Sniatecki [51] also performed an analysis of trace amounts of arsenic species in natural waters using hydride generation IPC-ICP-MS. Six arsenic species were determined with detection limits in the range 1.0-3.0 fig l-1 and total arsenic was determined using hydride generation by atomic fluorescence detection. It was found that the predominant species present in bottled mineral water samples was always As(V) with very low levels of As(III). The authors described how the system required . .. further work using special chromatographic software. .. to improve the quantitative measurement at a natural level. ... 

Coal contains several elements whose individual concentrations are generally less than 0.01%. These elements are commonly and collectively referred to as trace elements. These elements occur primarily as part of the mineral matter in coal. Hence, there is another standard test method for determination of major and minor elements in coal ash by ICP-atomic emission spectrometry, inductively coupled plasma mass spectrometry, and graphite furnace atomic absorption spectrometry (ASTM D-6357). The test methods pertain to the determination of antimony, arsenic, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, molybdenum, nickel, vanadium, and zinc (as well as other trace elements) in coal ash. 

Hahn et al. [105] used a hydride generation/condensation system with an ICP polychromator for the determination of arsenic, bismuth, germanium, antimony, selenium and tin in plant materials. 

Pahlavanpour et al. [115] has described a method based on hydride generation and ICP-emission spectrometry for the determination of arsenic, antimony and bismuth in herbage. 

In thermospray interfaces, the column effluent is rapidly heated in a narrow bore capillary to allow partial evaporation of the solvent. Ionisation occurs by ion-evaporation or solvent-mediated chemical ionisation initiated by electrons from a heated filament or discharge electrode. In the particle beam interface the column effluent is pneumatically nebulised in an atmospheric pressure desolvation chamber this is connected to a momentum separator where the analyte is transferred to the MS ion source and solvent molecules are pumped away. Magi and Ianni (1998) used LC-MS with a particle beam interface for the determination of tributyl tin in the marine environment. Florencio et al. (1997) compared a wide range of mass spectrometry techniques including ICP-MS for the identification of arsenic species in estuarine waters. Applications of HPLC-MS for speciation studies are given in Table 4.3. 

A number of techniques have been used for the speciation of arsenic compounds. The most important has been the formation of volatile hydrides of several species, separation by gas chromatography and detection by AAS. HPLC has been used to separate arsenic species. Several types of detectors have been studied for the determination of arsenic species in the column effluent. These have included AAS both off- and on-line, ICPAES and ICP-MS. An important comparative study of coupled chromatography-atomic spectrometry methods for the determination of arsenic was published (Ebdon et al., 1988). Both GC and HPLC were used as separative methods, and the detectors were FAAS, flame atomic fluorescence spectrometry (FAFS) and ICPAES. The conclusions were (1) that hydride generation and cryogenic trapping with GC-FAAS was the most... 

Although the sample is protected from losses by volatilization, unwanted materials, especially carbon, are also not removed, and these can cause problems in some cases. For samples containing much organic material, the carbon remaining in the samples after this wet ashing can interfere with the determination of several metals especially arsenic and selenium by ICP-MS [92],... 

Water-soluble tertiary amines enhance signals and decrease polyatomic chloride interferences in the ICP-MS determination of As and Se in food samples [22]. Arsenic and Se ICP-MS determination parameters have been optimized by a simplex procedure with amines in Ar plasma. A simple, direct, quantitative procedure for As and Se determination in food samples was set up, that provides good accuracy and Rt-for-purpose LoDs. 

A simple ICP-MS analysis procedure for biological materials was developed based on the extraction with a commercial, water-soluble tertiary amine solution [13]. Arsenic, Ba, Ca, Cr, Cu, Mn, Mo, Pb, Rb, Se, and Zn were determined. 

A. Chatterjee, Determination of total cationic and total anionic arsenic species in oyster tissue using microwave-assisted extraction followed by HPLC-ICP-MS,... 

J. Mattusch, R. Wennrich, Determination of anionic and cationic species of arsenic by ion chromatography with ICP-MS detection in environmental samples, Anal. 

---