Speciation of Arsenic Compounds by Coupling High-Performance Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry
Institute of Chemistry, Karl-Franzens-Universität Graz, Gratz, Styria, AustriaMicrochimica Acta (Impact Factor: 3.74). 02/1998; 130(1):71-79. DOI: 10.1007/BF01254593
There is considerable evidence that toxicity and physiological behavior of arsenic depends on its chemical forms. Arsenic speciation became therefore the subject of increasing interest in recent years. A sensitive method for the determination of arsenic species has been developed. The proposed procedure involves the use of high-performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Six arsenic compounds were separated by anion-exchange chromatography with isocratic elution using tartaric acid as mobile phase with an elution order: arsenocholine, arsenobetaine, dimethylarsinic acid, methylarsonic acid, arsenous acid and arsenic acid. The chromatographic parameters affecting the separation of the arsenic species were optimized. Analytical characterization of the method has been realized with standard solutions. The detection limits for six arsenic compounds were from 0.04 to 0.6 g/L as As element. The repeatability (expressed by R.S.D) was better than 7% for all investigated compounds. The HPLC-ICP-MS system was successfully applied to the determination of arsenic compounds in environmental and biological samples in g/L level.
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ABSTRACT: A new method for the simultaneous separation and determination of four arsenic species [As(III), As(V), monomethylarsonic acid and dimethylarsinic acid], three selenium species [Se(IV), Se(VI) and selenomethionine] as well as Sb(III) and Sb(V) is presented. The speciation was achieved by on-line coupling of anion exchange high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS). Chromatographic parameters such as the composition and pH of the mobile phase were optimised. Limits of detection are below 4.5 μg L–1 (as element) for Sb(III) and the selenium species and below 0.5 μg L–1 for the other species. Precisions of retention times were better than 2% RSD and of peak areas better than 8% RSD for all the species investigated.Fresenius Journal of Analytical Chemistry 07/1999; 364(5):462-466. DOI:10.1007/s002160051368
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ABSTRACT: Urinary arsenic metabolites are used in epidemiological studies to assess arsenic exposure. However, to ensure reliable application of the biomarker, further development is needed. This research contributes to the validation of urinary arsenic metabolites as arsenic exposure biomarkers in a subsample of 167 bladder cancer cases and 254 controls enrolled in a large case-control study in Southeastern Michigan. This work aims to develop an analytical protocol to speciate arsenic metabolites in urine, assess the reliability of sampling strategies, the exposure-biomarker relationship, and the relationship between the biomarker and disease. Information on demographics, smoking, dietary intake and drinking water intake was collected from participants. Urine samples were speciated using an HPLC-ICPMS coupled-system. Six species were measured As[III], As[V], DMA[V], MMA[V], MMA[III], and Arsenobetaine. The sum of As[III], As[V], MMA[V], and DMA[V] was designated total arsenic (TotAs). A subpopulation (n=131) provided additional urine samples to compare the arsenic levels in spot and first morning void (FMV) samples. The interclass correlation coefficient between TotAs in FMV and TotAs in spot samples showed that 90% of variation comes from between individuals and not within individuals. Drinking water arsenic concentration was a significant predictor (p<0.0001) of TotAs (R2=0.17). The correlation increased to 0.24 (p<0.0001) and 0.39 (p<0.0001) when the exposure was categorized by arsenic concentrations in water (≥1µg/L) and water intake (above and below median), respectively. Significant associations between TotAs and bladder cancer suggest that individuals who ingest elevated levels of arsenic may retain the metalloid in their bodies. However, sample size limitations and study design have to be considered when evaluating these associations. These results indicate that urinary arsenic metabolites can be used as biomarkers to assess recent arsenic intake via drinking water. Categorical estimates of water consumption better characterize intake in this population. Selection of adequate exposure measures may reduce misclassification in self-reported water consumption. FMV and spot samples can be used without preference when evaluating arsenic exposure in epidemiological studies. These results advance the validation process of urinary arsenic metabolites as biomarkers of arsenic exposure which are essential tools in risk assessment and epidemiological studies. Ph.D. Environmental Health Sciences University of Michigan, Horace H. Rackham School of Graduate Studies http://deepblue.lib.umich.edu/bitstream/2027.42/63654/1/zorimar_1.pdf
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ABSTRACT: The red cell membrane with its bilipid layer, integral membrane proteins (especially the GPs and band 3), and the red cell skeleton pose a formidable barrier for the malarial parasite to overcome during invasion. Invasion is an ordered and sequential process, indicating a highly complex and specific process involving numerous molecular interactions. For P. vivax and P. knowlesi infections the Duffy glycoprotein seems to be a specific requirement in invasion. For P. falciparum the GPs, and especially the N-acetyl neuraminic acid linked in an alpha 2-3 configuration on them, appear to act as specific ligands although some strains of P. falciparum may use alternate ligands for invasion. The parasite enters the red cells within an invagination continuous with the red cell bilipid layer, the parasitophorous vacuole membrane, and recent evidence would indicate that this membrane is largely of parasite origin. The numerous occasions in which the red cell needs to deform during invasion indicates that membrane deformability could be an important factor in determining invasion, but the dissociation of invasion and deformability as induced by a number of reagents would not support this contention. Instead it is suggested that reagents which modify invasion may be acting via alterations in red cell or parasite protein phosphorylation or dephosphorylation.Baillière s Clinical Haematology 07/1993; 6(2):513-34. DOI:10.1016/S0950-3536(05)80157-X
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