Determination of Arsenic Species in Marine Samples by HPLC-ICP-MS

Abstract

IntroductionAs far we have developed the very high sensitive methods for determining trace and ultratrace elements by combination between flow injection analysis (FIA) with on-line column preconcentrating techniques and inductively coupled plasma mass spectrometry (ICP-MS), such as trace metals (Cr(III), Al, V, Mn, Co, Ni, Cu, Zn, Mo, Cd, Pb and U) in seawater 1-3 and rare earth elements (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in seawater. [4][5][6] Therefore, since an ICP-MS instrument is a high sensitive detector, a hyphenated method by combination between high performance liquid chromatography (HPLC) and ICP-MS, is promising to be sensitive.Speciation of arsenic has acquired significant attention over the past 20 years in both mechanistic and exposure assessment research, because of toxicity of arsenic. While inorganic arsenic species As V and As III have been classified as carcinogenic, the methylated forms, MMA, and DMA have recently been identified as cancer promoters. It is believed that arsenobetaine and arsenocholine, which are highly methyl substituted, are considered to be non toxic. Depending on the kind of organism, different kind and concentrations of arsenic compounds were observed.In fish and crustaceans, arsenobetaine is a dominant species along with trace of MMA, DMA, TeMAs and TMAO. [1][2][3][4][5][6] In marine organism, more than 17 different inorganic and organic species have been reported. 7 In marine algae, arsenosurgars compounds (derivatives of dimethylarsinoylribosides and trimethylarsonioribosides) are most abundant. [2][3][4][5][6][7] The analytical speciation of arsenic has been achieved with the use of coupled techniques, which combine a separation process (chromatography) with suitable detection. Hydride generation atomic absorption spectrometry (HG-AAS) has been used for arsenic speciation in which online thermal or microwave oxidation was employed for converting many organoarsenicals into hydride forming one. 8 Better sensitivity has been achieved with the use of HG-atomic fluorescence spectrometry (HG-AFS). [9][10][11] Nevertheless, ICP-MS [12][13][14][15][16][17][18][19] is widely used for arsenic speciation analysis since it offers extremely high sensitivity, large dynamic range and easy coupling to HPLC. Especially, electrospray tandem mass spectrometry (ES-MS/MS) 4,20-23 was used for structural verification of arsenosugar compounds.Arsenicals have widely varying ionic characteristics, which are pH dependent. The anionic species As III , As V , DMA and MMA, can usually be resolved using anion exchange HPLC. Arsenobetaine (pKa 2.2) may be cationic or zwitter ionic. Cation exchange can be used to separate the cationic species arsenobetaine, arsenocholine, TeMAs and TMAO. 13Alternatively, ion pairing reversed phase HPLC can be used to resolve inorganic and organoarsenicals in single chromatographic run with help of ion pairing agents. Tetrabutyl ammonium hydroxide is common ion pairing agent used for separating anionic species and pentanesulfonate or hex...

Rapid and Effective Speciation Analysis of Arsenic Compounds in Human Urine using Anion‐Exchange Columns in HPLC‐ICP‐MS

“…It is known that seafood and marine samples contain various organic arsenic compounds, such as AsBe, AsCho, DMA, and AsSug 15) . Using liquid chromatography coupled to tandem quadrupole mass spectrometry, we found six oxo-arsenosugars in extracts from hijiki seaweed sold in a Japanese market 16) .…”

A biological indicator of inorganic arsenic exposure using the sum of urinary inorganic arsenic and monomethylarsonic acid concentrations

“…For the biological monitoring of exposure to iAs, the seafood intake should not interfere with the urinary concentrations of iAs metabolites 2,3 ) . ACGIH and DFG use the total concentration of urinary iAs+MMA+DMA, excluding AsBe, for the biological monitoring of occupational exposure to iAs 2,16) , because AsBe is the main arsenic compound in fish and shellfish 4,18 ) . ACGIH reported that the urinary arsenic concentrations in the general population were approximately 10 μg As/l in European countries and the United States and approximately 50 μg As/l in Japan 2) .…”

“…The total concentration of iAs and its metabolites, MMA and DMA, excreted in urine has been used for the biological monitoring of occupational iAs exposure by the American Conference of Governmental Industrial Hygienists (ACGIH) and Deutsche Forschungsgemeinschaft ( DFG ) 2,3 ) . In addition to DMA, methylated arsenics such as arsenobetaine (AsBe), arsenocholine (AsCho), and arsenosugars (AsSugs) are abundant in seafood products 1,4 ) . Although AsBe is only minimally metabolized in mammals 5) , AsCho and AsSug are extensively metabolized to AsBe and DMA 6,7) , respectively.…”

Chemical Speciation of Trace Metals in Seawater: a Review

“…Many analytical techniques have been developed for the chemical speciation of elements in environmental samples: typically, sequential leaching methods, [3][4][5][6][7] hyphenated techniques, [8][9][10][11][12] such as GC-ICP-MS (analysis of organometallic elements), X-ray spectroscopic techniques and others. [13][14][15] These methods provide significant information on the chemical forms of elements in the environment.…”