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Although the accumulation of arsenic (As) in human blood is linked with some diseases and with occupational exposure, there are few reports on speciation of As in blood. On the basis of our earlier article, elevated level of arsenicals in human urine and blood were found in the ex-exposed population via As-containing drinking water. The aim of the present study was to get an insight on impact of As in foodstuffs on the people living in the As-affected areas. Moreover, speciation of arsenicals in urine, and water-samples found in arsenobetaine (AsB). Since sampling population (n=25) was not taking any seafood, As in foodstuffs was thought to be the prime source for this discrepancy. So, speciation of methanol extract of freeze-dried red blood cells (RBCs) and foodstuffs, and trichloro acetic acid (TCA) treated plasma by high performance liquid chromatography-inductively coupled argon plasma mass spectrometer (HPLC-ICP MS) collected from the study population (n=33) was carried out to support our hypothesis. Results showed that urine contained AsB (1.7%), arsenite (iAs(III)) (14.3), arsenate (iAs(V)) (4.9), monomethylarsonous acid (MMA(III)) (0.64), monomethylarsonic acid (MMA(V)) (13.6), dimethylarsinous acid (DMA(III)) (7.7), and dimethylarsinic acid (DMA(V)) (65.4). Blood contained 21.3 microg L(- 1) (mean) As and of which 27.3% was in plasma and 72.7% in RBCs. RBCs contained AsB (21.6%) and DMA(V) (78.4) and blood plasma contained AsB (12.4%), iAs(III) (25.9), MMA(V) (30.3), and DMA(V) (31.4). Furthermore, speciation of As in foodstuffs showed that most of them contained AsB (3.54-25.81 microg kg(- 1)) (25.81-312.44 microg kg(- 1)) along with iAs(III) (9.62-194.93), iAs(V) (17.63-78.33), MMA(V) (9.47-73.22) and DMA(V) (13.43-101.15) that supported the presence of AsB and elevated As in urine and blood samples of the present study group. Inorganic As (iAs) predominates in rice (67.17-86.62%) and in spices (40-90.35%), respectively over organic As. So, As in the food chain is a real threat to human health.
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PMID:Impact of arsenic in foodstuffs on the people living in the arsenic-affected areas of West Bengal, India. 1795 75

Chronic exposure to arsenic causes a wide range of diseases such as hyperkeratosis, cardiovascular diseases, and skin, lung, and bladder cancers, and millions of people are chronically exposed to arsenic worldwide. However, little is known about the mechanisms underlying these toxic actions. The metabolism of arsenic is essential for understanding the toxic actions. Here, we identified the major arsenic-binding protein (As-BP) in the plasma of rats after oral administration of arsenite by the use of two different HPLC columns, gel filtration and anion exchange ones, coupled with an inductively coupled argon plasma mass spectrometer (ICP MS). The molecular mass of the As-BP was estimated to be 90 kDa based on results using the former column, and arsenic bound to this protein only in the form of dimethylarsinous acid (DMA (III)) in the plasma in vivo. In addition, the purified As-BP was shown to consist of two different proteins, haptoglobin (Hp) of 37 kDa (three bands) and the hemoglobin (Hb) alpha chain of 14 kDa (single band), using sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS), respectively, suggesting that the As-BP was the ternary DMA (III)-Hb-Hp complex. To confirm the present observations, an arsenic-binding assay was carried out in vitro . Although DMA (III) bound directly to fresh rat plasma proteins, they were different from that identified in vivo. However, when a DMA (III)-exposed rat RBC lysate (DMA (III) binds to Hb in rat RBCs) was added to control rat plasma, a new arsenic peak increased at the expense of the arsenic-Hb one. Furthermore, this new arsenic peak was consistent with the As-BP identified in the plasma in vivo, suggesting that arsenic bound to Hb further binds to haptoglobin (Hp), forming the ternary As-Hb-Hp complex.
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PMID:Identification of the major arsenic-binding protein in rat plasma as the ternary dimethylarsinous-hemoglobin-haptoglobin complex. 1824 22

A fast and reliable high-pressure liquid chromatography (HPLC)-inductively coupled plasma-mass spectrometry (ICP-MS) routine method was developed for the determination of inorganic arsenic [As(III) and As(V)], organic monomethylarsonate [MMA(V)], dimethylarsinate [DMA(V)], and arsenobetaine (As-B) in human urine. The complete method validation is described, including internal and external quality assurance. Limits of quantification for the As species are 0.1 microg/L, which is sufficient to determine background concentrations of the arsenic species in human urine. Additionally, total As in all urine samples was determined by conventional ICP-MS. Mean concentrations for 82 non-exposed inhabitants from northern Germany are 12.7, 5.9, 4.0, 0.23, 0.52, and 0.17 microg/L for total As, As-B, DMA(V), As(III), MMA(V), and As(V), respectively. Approximately 15% of the total As was not identified by the anion exchange HPLC-ICP-MS method, and could be other As metabolites in urine. Two case studies underline the need for As speciation, especially when total urinary arsenic concentrations are elevated. In the first case, we investigated the effect of seafood consumption on the concentration of different arsenic species in urine for different persons. A maximum enhancement of total As from 1 up to 2,200 microg/L (2,000 microg/L for As-B) was observed after a normal fish meal. The second case describes the exposure of a 7-year-old child to As(III) by inhalation of calcium arsenite powder. Five hours after exposure, the concentrations in the child's urine for As-B, DMA(V), As(III), MMA(V), and As(V) were < 0.1, 189, 304, 229, and 27 microg/L, respectively, and these concentrations were reduced to normal background values after 4 days.
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PMID:Fast determination of arsenic species and total arsenic in urine by HPLC-ICP-MS: concentration ranges for unexposed german inhabitants and clinical case studies. 1843 Feb 99

The inorganic arsenic species As(III), As(V) and the organic species methylarsonate (MMA(V)), dimethylarsinate (DMA(V)) and arsenobetaine (AsB) were determined in human urine by a fast anion exchange HPLC-ICP-MS method, which was developed for clinical laboratories with high sample throughput. This paper compares typical chromatograms of the arsenic species in urine samples collected in different medical cases, for example, for the non-exposed population, for environmentally (plant protectants) and occupationally (glass manufacture) exposed persons, for a person after a failed suicide attempt with As2O3 and for persons before and after administration of the antidot sodium 2,3-dimercapto-1-propane-sulfonate (DMPS). Concentration data of the urinary As species for the non-exposed German population (n=82) are compared with the concentrations before and after administration of DMPS (n=37). For the non-exposed group the toxicologically relevant As in urine consists of 81% DMA(V), 10% MMA(V) and 9% inorganic As. However, a few hours after an acute intoxication with inorganic As this distribution changes dramatically and As(III) and As(V) are predominantly found in urine. After treatment with DMPS the total As concentration increases significantly and mainly MMA(V) and As(III) were found in urine samples.
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PMID:Comparison of different medical cases in urinary arsenic speciation by fast HPLC-ICP-MS. 1894 60

A procedure for arsenic species fractionation in alga samples (Sargassum fulvellum, Chlorella vulgaris, Hizikia fusiformis and Laminaria digitata) by extraction is described. Several parameters were tested in order to evaluate the extraction efficiency of the process: extraction medium, nature and concentration (tris(hydroxymethyl)aminomethane, phosphoric acid, deionised water and water/methanol mixtures), extraction time and physical treatment (magnetic stirring, ultrasonic bath and ultrasonic focussed probe). The extraction yield of arsenic under the different conditions was evaluated by determining the total arsenic content in the extracts by ICP-AES. Arsenic compounds were extracted in 5mL of water by focussed sonication for 30s and subsequent centrifugation at 14,000xg for 10min. The process was repeated three times. Extraction studies show that soluble arsenic compounds account for about 65% of total arsenic. An ultrafiltration process was used as a clean-up method for chromatographic analysis, and also allowed us to determine the extracted arsenic fraction with a molecular weight lower than 10kDa, which accounts for about 100% for all samples analysed. Speciation studies were carried out by HPLC-ICP-AES. Arsenic species were separated on a Hamilton PRP-X100 column with 17mM phosphate buffer at pH 5.5 and 1.0mLmin(-1) flow rate. The chromatographic method allowed us to separate the species As(III), As(V), MMA and DMA in less than 13min, with detection limits of about 20ng of arsenic per species, for a sample injection volume of 100muL. The chromatographic analysis allowed us to identify As(V) in Hizikia (46+/-2mugg(-1)), Sargassum (38+/-2mugg(-1)) and Chlorella (9+/-1mugg(-1)) samples. The species DMA was also found in Chlorella alga (13+/-1mugg(-1)). However, in Laminaria alga only an unknown arsenic species was detected, which eluted in the dead volume.
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PMID:Optimisation of sample treatment for arsenic speciation in alga samples by focussed sonication and ultrafiltration. 1897 Apr 94

Although metabolism of arsenicals to form methylated oxoarsenical species has been extensively studied, less is known about the formation of thiolated arsenical species that have recently been detected as urinary metabolites. Indeed, their presence suggests that the metabolism of ingested arsenic is more complex than previously thought. Recent reports have shown that thiolated arsenicals can be produced by the anaerobic microflora of the mouse cecum, suggesting that metabolism prior to systemic absorption may be a significant determinant of the pattern and extent of exposure to various arsenic-containing species. Here, we examined the metabolism of 34S labeled dimethylthioarsinic acid (34S-DMTA(V)) by the anaerobic microflora of the mouse cecum using HPLC-ICP-MS and HPLC-ESI-MS/MS to monitor for the presence of various oxo- and thioarsenicals. The use of isotopically enriched 34S-DMTA(V) made it possible to differentiate among potential metabolic pathways for production of the trimethylarsine sulfide (TMAS(V)). Upon in vitro incubation in an assay containing anaerobic microflora of mouse cecum, 34S-DMTA(V) underwent several transformations. Labile 34S was exchanged with more abundant 32S to produce 32S-DMTA(V), a thiol group was added to yield DMDTA(V), and a methyl group was added to yield 34S-TMAS(V). Because incubation of 34S-DMTA(V) resulted in the formation of 34S-TMAS(V), the pathway for its formation must preserve the arsenic-sulfur bond. The alternative metabolic pathway postulated for formation of TMAS(V) from dimethylarsinic acid (DMA(V)) would proceed via a dimethylarsinous acid (DMA(III)) intermediate and would necessitate the loss of 34S label. Structural confirmation of the metabolic product was achieved using HPLC-ESI-MS/MS. The data presented support the direct methylation of DMTA(V) to TMAS(V). Additionally, the detection of isotopically pure 34S-TMAS(V) raises questions about the sulfur exchange properties of TMAS(V) in the cecum material. Therefore, 34S-TMAS(V) was incubated and the exchange was monitored with respect to time. The data suggest that the As-S bond associated with TMAS(V) is less labile than the As-S bond associated with DMTA(V).
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PMID:Exploring the in vitro formation of trimethylarsine sulfide from dimethylthioarsinic acid in anaerobic microflora of mouse cecum using HPLC-ICP-MS and HPLC-ESI-MS. 1913 83

A pilot study was conducted to determine the applicability of toenails as a biomarker of exposure to elevated environmental arsenic (As) levels. A total of 17 individuals were recruited for the pilot study: 8 residents living near to a former As mine, Devon, UK, forming the exposed group, plus 9 residents from Nottinghamshire, UK, with no anticipated As exposure who were used for comparison as a control group. All toenail samples were thoroughly washed prior to analysis and the wash solutions retained for As determination via ICP-MS to provide an indication of the background environmental As levels for each group. Total As was determined in washed toenail samples via ICP-MS following microwave assisted acid digestion. Concentrations of total As in the toenails of the exposed group were elevated, ranging from 858 to 25 981 microg kg(-1) (geometric mean = 5406 microg kg(-1)), compared to the control group whose toenail As concentrations ranged from 73 to 273 microg kg(-1) (geometric mean = 122 microg kg(-1)). Higher levels of exogenous As contamination were present on the toenails of the exposed group (geometric mean = 506 microg kg(-1)) compared to the control group (geometric mean = 4.0 microg kg(-1)) providing evidence of higher environmental As levels in the exposed group. Total As concentrations in toenail samples were positively correlated to environmental As levels (r = 0.60, p < 0.001). HPLC-ICP-MS analysis of aqueous toenail extracts revealed inorganic arsenite (As(III)) to be the dominant species extracted ( approximately 83%) with lesser amounts of inorganic arsenate (As(V)) and organic dimethylarsinate (DMA(V)) at approximately 13% and approximately 8.5%, respectively. Arsenic speciation in analysed toenail extracts from the two groups was comparable. The only notable difference between groups was the presence of small amounts (<1%) of organic methylarsonate (MA(V)) in two toenail samples from the exposed group. Toenails are presented as a viable biomarker of exposure at sites with elevated environmental As, such as the former mining sites found throughout Devon and Cornwall, UK.
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PMID:Human toenails as a biomarker of exposure to elevated environmental arsenic. 1928 39

Two species of arsenic (As) resistant earthworm, Lumbricus rubellus and Dendrodrillus rubidus, their host soils and soil excretions (casts) were collected from 23 locations at a former As mine in Devon, UK. Total As concentrations, measured by ICP-MS, ranged from 255 to 13,080 mg kg(-1) in soils, 11 to 877 mg kg(-1) in earthworms and 284 to 4221 mg kg(-1) in earthworm casts from a sub-sample of 10 of the 23 investigated sites. The samples were also measured for As speciation using HPLC-ICP-MS to investigate potential As biotransformation pathways. Inorganic arsenate (As(V)) and arsenite (As(III)) were the only species detected in the soil. As(V) and As(III) were also the dominant species found in the earthworms and cast material together with lower proportions of the organic species methylarsonate (MA(V)), dimethylarsinate (DMA(V)), arsenobetaine (AB) and three arsenosugars. Whilst the inorganic As content of the earthworms increased with increasing As body burden, the concentration of organic species remained relatively constant. These results suggest that the biotransformation of inorganic arsenic to organic species does not contribute to As resistance in the sampled earthworm populations. Quantification of As speciation in the soil, earthworms and cast material allows a more comprehensive pathway for the formation of AB in earthworms to be elucidated.
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PMID:Arsenic biotransformation in earthworms from contaminated soils. 1965 32

In this work, dual-column capillary microextraction (CME) system consisting of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPTS)-silica coated capillary (C1) and 3-mercaptopropyl trimethoxysilane (MPTS)-silica coated capillary (C2) was developed for sequential separation/preconcentration of arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)] in the extracts of human hair followed by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) detection with iridium as permanent modifier. Various experimental parameters affecting the dual-column microextraction of different As species had been investigated in detail. It was found that at pH 9, As(V) and MMA could be quantitatively retained by C1 and only As(III) could be quantitatively retained by C2. With the aid of valve switching, As(V)/MMA(V) retained on C1 and As(III) retained on C2 could be sequentially desorbed by 10 microl of 0.01 mol l(-1) HNO(3) [for As(V)], 0.1 mol l(-1) HNO(3) [for MMA(V)] and 0.2 mol l(-1) HNO(3)-3% thiourea (m/v) [for As(III)], respectively, the eluents were immediately introduced into the Ir-coated graphite tubes for further ETV-ICP-MS detection. With two-step ETV pyrolysis program, Cl(-) in the sample matrix could be in situ removed, and the total As in the human hair extracts or digested solution could be interference-free, determined by ETV-ICP-MS. DMA(V) in the human hair extracts was obtained by subtraction of total As in the human hair extracts from other three As species. Under the optimized conditions, the detection limits (3 sigma) of the method were 3.9 pg ml(-1) for As(III), 2.7 pg ml(-1) for As(V), 2.6 pg ml(-1) for MMA(V) and 124 pg ml(-1) for total As with the relative standard deviations less than 7.0% (C = 0.1 ng ml(-1), n = 7), and the enrichment factor was 286, 262 and 260 for As(III), As(V) and MMA(V), respectively. The developed method was successfully applied for the speciation of arsenic in the extracts of human hair.
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PMID:Dual-column capillary microextraction (CME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) for the speciation of arsenic in human hair extracts. 1995 Jan 10

Based on gradient anion exchange chromatography (AEC), a new strategy in As-speciation was evaluated. A narrow bore chromatographic system with lower flow rates (<or=300 microL) well suitable for the low flow requirements of higher efficiency nebulizers was splitless coupled to a high resolution sector field ICP MS. The AEC system takes full advantage of the detector sensitivity allowing more diluted samples (50-100 times) to be injected, delivering substantially less sample matrix to the column and a lower eluent load to the plasma. The unique plasma compatibility of the NH(4)NO(3)-eluent salt used in this study enabled high linear salt ramps in gradient applications, highly reproducible retention times (+/-1%) and detection limits in the low ng/L range. The separation conditions were applied on two different polymeric anion-exchangers: a low capacity, weakly hydrophobic material (AS11, Dionex) and a more frequently used higher capacity, higher hydrophobic material (AS7, Dionex). On both columns, As-species (As(III/V), MMA, DMA, AsB) and Cl(-) were separated in less than nine minutes and co-elution was circumvented by adapting the separation pH to the optimal column selectivity. The key-advantage of the NH(4)NO(3)-eluent is that it can adopt any separation pH without compromising the eluent strength which is not possible with all other eluents used so far. The influences of chloride and methanol were investigated and found not to affect the chromatographic performance. Column deposits caused strong reversible As(v) adsorption which reduced As(v) to As(III). A corresponding phosphate excess in the injected sample eliminated the adsorption and prevented artefacts in As(v)/As(III) ratios. The method applied to ground water samples provided robust separations and is compatible with any sample preservation procedure.
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PMID:Arsenic speciation by gradient anion exchange narrow bore ion chromatography and high resolution inductively coupled plasma mass spectrometry detection. 2018 76


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