High-performance Liquid Chromatography Hydride Generation Research Articles

Arsenic Trioxide Therapy During Pregnancy: ATO and Its Metabolites in Maternal Blood and Amniotic Fluid of Acute Promyelocytic Leukemia Patients.

Acute promyelocytic leukemia (APL) is extremely fatal if treatment is delayed. Management of APL in pregnancy is a challenging situation. Arsenic trioxide (ATO) is successfully applied to treat APL. ATO can be transformed into different arsenic species [arsenite (AsIII), monomethylated arsenic (MMA, consists of MMAIII and MMAV), dimethylated arsenic (DMA, consists of DMAIII and DMAV), and arsenate (AsV)], which produce different toxic effects. Investigating the maternal and fetal exposure to arsenic species is critical in terms of assessing maternal and fetal outcomes, choice of optimal treatment, and making decisions for attempting to preserve the obstetrical and fetal wellbeing. In this study, maternal blood and amniotic fluid (AF) from APL patients treated with ATO in pregnancy and blood samples of non-pregnant patients were collected. Concentrations of inorganic arsenic (iAs, iAs = AsIII+AsV), MMA, and DMA were analyzed by high-performance liquid chromatography–hydride generation–atomic fluorescence spectrometry (HPLC–HG–AFS). The difference in arsenic species of plasma between pregnant patients and non-pregnant patients, distribution of arsenic compounds in AF and maternal plasma, and arsenic penetration into AF were explored. The outcomes of pregnant women treated with ATO and their fetus were analyzed. No significant differences in arsenic concentration, percentage, and methylation index [PMI: primary methylation index (MMA/iAs); SMI: secondary methylation index (DMA/MMA)] between pregnant women and non-pregnant women (p > 0.05) were observed. The mean ratios of AF to maternal plasma were as follows: iAs, 2.09; DMA, 1.04; MMA, 0.49; and tAs, 0.98. Abortion rate is higher with the diagnosis at an earlier gestational age, with 0%, 67%, and 100% of pregnancies ending in abortion during the third, second, and first trimester, respectively. The age of the pregnant women, the dose of ATO, and the duration of fetal exposure in utero had no influence on fetal outcomes. All APL women achieved complete remission (CR). Collectively, ATO and its metabolites can easily cross the placenta. Levels and distribution of arsenic species in maternal plasma and AF gave evidence that arsenic species had a different ability to penetrate the placenta into AF (iAs > DMA > MMA) and indicated a relatively high fetal exposure to ATO and its metabolites in utero. Gestational age at diagnosis was more likely to be closely related to fetal outcomes, but had no effects on mother outcomes.

Gender difference in arsenic biotransformation is an important metabolic basis for arsenic toxicity

BackgroundArsenic metabolism enzymes can affect the toxic effects of arsenic. However, the effects of different genders on the metabolites and metabolic enzymes in liver arsenic metabolism is still unclear. This study analyzed the gender differences of various arsenic metabolites and metabolic enzymes and further explored the effects of gender differences on arsenic metabolism in liver tissues of rats.MethodsRats were treated with high/medium/low doses of iAs3+ or iAs5+. Liver pathological changes were observed with electron microscopy. The monomethyl aracid (MMA) and dimethyl aracid (DMA) was determined by high performance liquid chromatography-hydride generation atomic fluorescence spectroscopy. S-adenosylmethionine (SAM), arsenate respiratory reductase (ARR), nicotinamide adenine dinucleotide (NAD), purine nucleoside phosphorylase (PNP), pyruvate kinase (PK), and myeloperoxidase (MPO) SAM, ARR, NAD, PNP, PK, and MPO were determined by enzyme-linked immunoassay. RT-qPCR was used to determine Arsenic (+ 3 oxidation state) methyltransferase (AS3MT).ResultsThe iAs3+ and iAs5+ at high doses induced pathological changes in the liver, such as increased heterochromatin and lipid droplets. Compared within the same group, MMA and DMA were statistically significant in iAs3 + high, iAs3 + medium and iAs5+ low dose groups (P < 0.05). MMA of male rats in iAs3+ high and medium groups was higher than that of female rats, and the DMA of male rats was lower than that of female rats. As3MT mRNA in the male iAs3+ high group was higher than that of females. Besides, compared between male and female, only in iAS3+ low dose, iAS3+ medium dose, iAS5+ low dose, and iAS5+ medium dose groups, there was significant difference in SAM level (P < 0.05). Compared within the same group, male rats had significantly higher PNP and ARR activities while lower PK activity than female rats (P < 0.05). Between the male and female groups, only the iAS3+ high dose and medium dose group had a statistically significant difference (P < 0.05). The NAD activity of females in iAS3+ high dose group was higher than that of males.ConclusionThe gender differences in the arsenic metabolism enzymes may affect the biotransformation of arsenic, which may be one of the important mechanisms of arsenic toxicity of different sexes and different target organs.

Arsenic-Related Health Risk Assessment of Realgar-Containing NiuHuangJieDu Tablets in Healthy Volunteers Po Administration

Realgar, an arsenic-containing traditional Chinese medicine of As2S2, has significant therapeutic effects for hundreds of years. NiuHuangJieDu tablets (NHJDT) is one of the most commonly prescribed realgar-containing preparations for the treatment of sore throat, swelling, and aching of gums. However, realgar-containing TCMs raise great safety concerns due to the adverse effects reported by arsenic poisoning. In this study, the arsenic-related health risk assessment of NHJDT was conducted in healthy volunteers after single and multiple doses oral administration. Blood, plasma, and urine samples were collected after dosing at predetermined time points or periods. Simple, rapid, and sensitive methods were established for the quantification of total arsenic and arsenic speciation in biological samples. The total arsenic and arsenic speciation were determined by hydride generation-atomic fluorescence spectrometry (HG-AFS) and high-performance liquid chromatography–hydride generation–atomic fluorescence spectrometry (HPLC-HG-AFS), respectively. No significant fluctuation of total arsenic was observed in human blood, and no traces of arsenic speciation were found in human plasma. Dimethylarsenic acid was detected as the predominated arsenic species in human urine after dosing. Therapeutic dose administration of NHJDT was relatively safe in single dose for the limited blood arsenic exposure, but long-term medication may still pose health risks due to the accumulation of arsenics in blood and its extremely slow excretion rate. Therefore, arsenic exposure should be carefully monitored during realgar-containing TCM medication, especially for long-term regimen. The results obtained in this study will provide scientific references for the clinical application of realgar and its-containing TCMs.

Application of enzymatic probe sonication for selenium speciation in animal feeds

Enzymatic probe sonication (EPS) was investigated as a novel and alternative technology for the extraction of five Se species SeCys2, MeSeCys, Se (IV), SeMet and Se (VI) from animal feeds. The critical parameters of EPS such as enzyme types, ultrasonic power, sample/enzyme ratio, extraction time and temperature were carefully optimized. Under current conditions, one sample can be extracted in 60s, in contrast to several hours required by the conventional enzymatic methods Moreover, the extraction is performed in pure water, no further temperature control or pH adjustment is needed, and therefore the risk of species interconvertion is drastically reduced or inhibited. The Se species were separated and quantitatively determined by high-performance liquid chromatography-hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS), which allows the separation of organic and inorganic Se species in a single chromatographic run. The newly developed method was successfully applied to the determination of Se species in 18 feed samples collected from markets and local farms. Concerning the feed samples studied, the results of this work suggest that stricter measures should be taken to control the Se-enriched feed supplements in terms of Se species.

Photocatalytic degradation of roxarsone by using synthesized ZnO nanoplates

Abstract An efficient photodegradation of roxarsone (ROX) was achieved by using synthesized zinc oxide (ZnO) nanoplates under UV light irradiation. ZnO nanoplates were synthesized by facile wet chemical method. Characterization of ZnO nanoparticles was done by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, diffuse reflectance (DRS) UV–Visible absorption spectroscopy, BET analyzer, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained results reveal that the synthesized sample is ZnO which has hexagonal structure and plate-like morphology. The band gap and specific surface area of ZnO was found to be 3.02 eV and 7 m2 g−1 respectively. ROX’s degradation by-products such as As(III), As(V) were analyzed by high performance liquid chromatography-hydride generation coupled with atomic absorption spectrometry (HPLC-HG-AAS). The photogenerated hydroxyl ( ) and carbon-centered radicals were detected by electron paramagnetic resonance (EPR) spectroscopy. According to experimental evidences a possible photocatalytic mechanism has also been proposed. Photocatalytic degradation of ROX leads to mineralization as CO2 and As(V). This can be considered as a promising method for removing ROX from contaminated waters.

Arsenic exposure from drinking water is associated with decreased gene expression and increased DNA methylation in peripheral blood

BackgroundExposure to inorganic arsenic increases the risk of cancer and non-malignant diseases. Inefficient arsenic metabolism is a marker for susceptibility to arsenic toxicity. Arsenic may alter gene expression, possibly by altering DNA methylation. ObjectivesTo elucidate the associations between arsenic exposure, gene expression, and DNA methylation in peripheral blood, and the modifying effects of arsenic metabolism. MethodsThe study participants, women from the Andes, Argentina, were exposed to arsenic via drinking water. Arsenic exposure was assessed as the sum of arsenic metabolites in urine (U-As), using high performance liquid-chromatography hydride-generation inductively-coupled-plasma-mass-spectrometry, and arsenic metabolism efficiency was assessed by the urinary fractions (%) of the individual metabolites. Genome-wide gene expression (N=80 women) and DNA methylation (N=93; 80 overlapping with gene expression) in peripheral blood were measured using Illumina DirectHyb HumanHT-12 v4.0 and Infinium Human-Methylation 450K BeadChip, respectively. ResultsU-As concentrations, ranging 10–1251μg/L, was associated with decreased gene expression: 64% of the top 1000 differentially expressed genes were down-regulated with increasing U-As. U-As was also associated with hypermethylation: 87% of the top 1000CpGs were hypermethylated with increasing U-As. The expression of six genes and six individual CpG sites were significantly associated with increased U-As concentration. Pathway analyses revealed enrichment of genes related to cell death and cancer. The pathways differed somewhat depending on arsenic metabolism efficiency. We found no overlap between arsenic-related gene expression and DNA methylation for individual genes. ConclusionsIncreased arsenic exposure was associated with lower gene expression and hypermethylation in peripheral blood, but with no evident overlap.

On-line speciation and quantification of four arsenical species in rice samples collected in Argentina using a HPLC–HG–AFS coupling

An investigation was carried out to explore further the analytical capabilities of the coupling high performance liquid chromatography (HPLC)–hydride generation (HG)–atomic fluorescence spectrometry (AFS) for the reliable determination of the four toxicologically relevant arsenical species namely, As(III), As(V), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in rice. Fifty nine samples of rice of five different cultivars were collected in province of Entre Rios (Argentina). Samples were dried at 103±2°C and mild conditions were adopted for species extraction (0.28molL−1 HNO3 at 95±3°C for 90min). Method validation included, evaluation of linearity; limits of detection, 0.020μgg−1 for As(III) and 0.025μgg−1 for the other three species; precision (intermediate precision), 4% for As(III) and DMA, and 6% for the other two species; trueness (bias), 9% for As(III) and As(V) and 11% for the other two species, and uncertainty (obtained from validation data) varying from 9.5% for As(III) to 19% for As(V). Total arsenic concentrations ranged from 0.08 to 1.39mgkg−1. The mean concentrations of sum of the As species extracted and determined by HPLC–HG–AFS was approximately 99.7% of certified value for total As in NIST SRM “Rice flour”. Levels of the four species in the analyzed samples were in the order DMA>As(III)>As(V)>MMA. Inorganic As (iAs) accounted for 28% of the As detected. DMA exhibited the highest levels, representing a 72% of total grain As on average.

Health implications of the distribution of arsenic species in airborne particulate matter

Airborne particle samples were taken between 2001 and 2008 at an urban site (Huelva) in southwestern Spain. Arsenic was found in the samples due to the presence of a near-by copper smelter, sometimes at concentrations above the target value of 6ngm−3 proposed by EU regulations (annual means from 4.6 to 10.4ngAsm−3 in PM10, and 3.0 to 9.1ngAsm−3 in PM2.5). The results obtained by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) showed that arsenic accumulates preferentially (ca. 70–80%) in the particles with smaller diameter (PM2.5 versus PM10), representing a threat to human health due to the higher capacity of the finer particles to enter the organism through the respiratory system. Moreover, the toxicity of the inorganic arsenic species depends also on the oxidation state, As(III) being more toxic that As(V). The speciation analysis performed with High Performance Liquid Chromatography-Hydride Generation- Atomic Fluorescence Spectrometry (HPLC-HG-AFS) with samples collected between 2006 and 2008, showed that As(V) represented the main arsenic species, but As(III) was also found at significant concentration, representing a 5–10% of the total arsenic content. The results also indicate that the more toxic As(III) tends to concentrate preferentially in the finer fraction PM2.5 in comparison with As(V), thus representing an added health risk for the local population.

Rapid and direct speciation of methyltins in seawater by an on-line coupled high performance liquid chromatography–hydride generation–ICP/MS system

A novel on-line coupled HPLC–hydride generation (HG)–ICP/MS system was developed for rapid, direct and sensitive speciation of methyltins in seawater without any pretreatment step. Methyltin compounds were separated by reversed phase HPLC, and then on-line reacted with potassium borohydride and acetic acid to generate volatile hydride products. The volatile derivatization products were separated in the spray chamber of ICP/MS and then introduced into ICP/MS by argon gas for detection. Monomethyltin (MMT), dimethyltin (DMT) and trimethyltin (TMT) were baseline separated in less than 15 min by reversed phase HPLC. The influence of KBH 4 concentration and type of acid on the system performance was investigated and optimized. Calibration curves, based on peak heights against concentration, were linear in the range of 0.5–50 ng (Sn) mL −1 of methyltins with correlation coefficients of 0.9990, 0.9990 and 0.9996 for MMT, DMT and TMT, respectively. The relative standard deviations measured at 10 ng (Sn) mL −1 for these three methyltins were in the range of 0.6–1.4% ( n = 5), and the calculated detection limits (S/N = 3) for MMT, DMT and TMT were 0.266, 0.095 and 0.039 ng (Sn) mL −1, respectively. This method was successfully applied to the speciation of methyltins in seawater with spiked recovery in the range of 95.4–106.9%. MMT and DMT were detected in all the seawater samples with concentrations in the range of 1.0–1.5 and 0.30–0.57 ng (Sn) mL −1 for MMT and DMT, respectively.

Determination of soluble toxic arsenic species in alga samples by microwave-assisted extraction and high performance liquid chromatography–hydride generation–inductively coupled plasma-atomic emission spectrometry

A microwave-based procedure for arsenic species extraction in alga samples ( Sargassum fulvellum, Chlorella vulgaris, Hizikia fusiformis and Laminaria digitata) is described. Extraction time and temperature were tested in order to evaluate the extraction efficiency of the process. Arsenic compounds were extracted in 8 ml of deionised water at 90 °C for 5 min. The process was repeated three times. Soluble arsenic compounds extracted accounted for about 78–98% of total arsenic. The results were compared with those obtained in a previous work, where the extraction process was carried out by ultrasonic focussed probe for 30 s. Speciation studies were carried out by high performance liquid chromatography–hydride generation–inductively coupled plasma-atomic emission spectrometry (HPLC-HG-ICP-AES). The chromatographic method allowed us to separate As(III), As(V), monomethylarsonic acid and dimethylarsinic acid in less than 13 min. The chromatographic analysis of the samples allowed us to identify and quantify As(V) in Hizikia sample and Sargasso material, while the four arsenic species studied were found in Chlorella sample. In the case of Laminaria sample, none of these species was identified by HPLC-HG-ICP-AES. However, in the chromatographic analysis of this alga by HPLC-ICP-AES, an unknown arsenic species was detected.

The new concept of hyphenated analytical system: Simultaneous determination of inorganic arsenic(III), arsenic(V), selenium(IV) and selenium(VI) by high performance liquid chromatography–hydride generation–( fast sequential) atomic absorption spectrometry during single analysis

The paper presents a new conception of determination of inorganic speciation forms of arsenic: As(III) and As(V) as well selenium Se(IV) and Se(VI) by means of the high performance liquid chromatography hyphenated with a detection by the atomic absorption spectrometry with hydride generation (HPLC–HG–AAS). The application of optimization procedure conditions of chromatographic separation of arsenic and selenium speciation forms (using anion-exchange Supelco LC-SAX1 column and phosphate buffer at pH 5.40 as a mobile phase) as well as the use of the atomic absorption spectrometry as a detector, which enables work in fast sequential mode, allowed to develop original detection methodology of simultaneous determination of arsenic As(III), As(V) and selenium Se(IV) and Se(VI) speciation forms within a 220 s single analysis. The obtained detection limits were 7.8 ng mL −1 for As(III); 12.0 ng mL −1 for As(V); 2.4 ng mL −1 for Se(IV) and 18.6 ng mL −1 for Se(VI) and precision 10.5%, 12.1%, 14.2% and 17.3%, respectively, for 100 ng mL −1. The described method was used for ground water analysis.

Comparison of mild extraction procedures for determination of arsenic compounds in different parts of pepper plants (Capsicum annum, L.)

AbstractEight extraction agents (water, methanol–water mixtures in various ratios, methanol, a 20 mmol l−1 ammonium phosphate buffer, and a methanol–phosphate buffer) were tested for the extraction of arsenic compounds from fruits, stems + leaves, and roots of pepper plants grown on soil containing 17.2 mg kg−1 of total arsenic. The arsenic compounds in the extracts were determined using high‐performance liquid chromatography–hydride generation inductively coupled plasma mass spectrometry. Whereas pure water was the most effective extraction agent for fruits (87 ± 3.3% extraction yield) and roots (96 ± 0.6% extraction yield), the 20 mM ammonium phosphate buffer at pH 6 extracted about 50% of the arsenic from stems + leaves. Decreasing extractability of the arsenic compounds was observed with increasing methanol concentrations for all parts of the pepper plant. In pepper fruits, arsenic(III), arsenic(V), and dimethylarsinic acid (DMA) were present (25%, 37%, and 39% respectively of the extractable arsenic). Arsenic(V) was the major compound in stems + leaves and roots (63% and 53% respectively), followed by arsenic(III) representing 33% and 42% respectively, and small amounts (not exceeding 5%) of DMA and methylarsonic acid were also detected. Hence, for a quantitative extraction of arsenic compounds from different plant tissues the extractant has to be optimized individually. Copyright © 2005 John Wiley &amp; Sons, Ltd.

Arsenic speciation in river and estuarine waters from southwest Spain

An arsenic speciation survey was carried out in water samples from the Tinto and Odiel Rivers (southwest of Spain), as well as their common estuary. Both rivers are affected by acid mine drainage (AMD) and represent an input of heavy metals into the estuary, which also suffers from industrial water discharges. Samples were taken in December 2000 and July 2001. The arsenic species considered were arsenite (As(III)), arsenate (As(V)), monomethylarsonic (MMA) and dimethylarsinic (DMA) ions using coupled high-performance liquid chromatography–hydride generation–inductively coupled plasma-mass spectrometry (HPLC–HG–ICP-MS) for their determination. Parameters such as pH, salinity, redox potential and dissolved O 2 were also measured. The results revealed that the acid mine drainage originating mainly during winter along the upper part of the Tinto River course causes high inorganic concentrations of dissolved arsenic, up to 600 μg l −1 of As(III) and 200 μg l −1 of As(V). In summer, As(III) levels decreased due to the diminution of the input from acid mine drainage and also because of oxidation, with a corresponding increase of As(V) level. Furthermore, the extreme acidic conditions of this river (pH 2.3–2–6) do not allow biological activity sufficient to produce significant concentrations of methylated arsenic species. The arsenic concentrations in the nearby Odiel River were always 5–10 times lower than in the Tinto River, with arsenic levels usually below 100 μg l −1, dominated by As(V), indicating that it is less affected by acid mine drainage. The highest inorganic arsenic species concentrations were found where the river crosses a mining site, which corresponds to the highest As(III) values. Significant biological activity in this river produced methylated species that were detected along the watercourse, with the highest concentrations at the lower course of the river, accounting for up to 53–61% of the total dissolved arsenic. At the common estuary formed by both rivers, only arsenate was detected in most samples at lower concentrations than in the riverine water samples. The tidal cycle showed a similar pattern of dilution of the arsenate when seawater comes into the estuary. Methylated species were not found either in summer or winter, at least at the 0.1 μg l −1 level, possibly because of the high turbidity of the waters, producing an inhibition of the phytoplankton activity. In addition to the riverine inputs into the common estuary, industrial activity also represents an important source of arsenic as the discharge from a Cu smelter produced the highest arsenate level of all samples in estuary and also the only sample with significant arsenite concentration. Furthermore, the underlying iron-oxide-rich sediments represent an importance source of arsenic into the water column. In three nearby estuaries not affected by industrial activity or acid mine drainage, arsenic levels remained below detection limits.

Speciation of the immediately mobilisable As(III), As(V), MMA and DMA in river sediments by high performance liquid chromatography–hydride generation–atomic fluorescence spectrometry following ultrasonic extraction

In this work, a fast method is developed for the speciation of As(III), As(V), MMA and DMA in the immediately mobilisable fraction of river sediments (i.e. water-soluble and phosphate-exchangeable) by high performance liquid chromatography–hydride generation–atomic fluorescence detection (HPLC–HG–AFD) after extraction using focused ultrasound. The influence of relevant parameters influencing an ion-pairing chromatographic separation following isocratic elution (i.e. amount of MeOH in the mobile phase, ion pair reagent concentration, pH, flow rate) was studied. Focused ultrasound transmitted from an ultrasonic probe provided the same extractable contents as conventional extraction with no changes in the species distribution. The effect of the drying step over extraction of As species was investigated. The following drying procedures were compared: freeze-, oven-, microwave- and air-drying. No influence of the drying operation on the water-extractable fraction was observed. However, freeze- and air-drying yielded significantly higher phosphate-extractable amounts of As(III) and As(V) as compared to oven and microwaves. Detection limits for the As species were in the range 1.3–4.1 ng/g for the water-soluble fraction and 1.6–4.8 ng/g for the phosphate buffer exchangeable fraction. The method was applied to the speciation of immediately mobilisable As(III), As(V), DMA and MMA in 11 sediment samples collected along the beds of the Louro River (southern Galicia, Spain).

Arsenic methylation and bladder cancer risk in Taiwan.

The mechanism of arsenic detoxification in humans remains unclear. Data are especially lacking for low-level arsenic exposure. We hypothesize that arsenic methylation ability, defined as the ratios of monomethylarsonic acid (MMA(V))/inorganic arsenic (primary arsenic methylation index, PMI) and dimethylarsinic acid (DMA(V))/ MMA(V) (secondary arsenic methylation index, SMI), may modify the association between cumulative arsenic exposure (CAE, mg/L-year) and the risk of bladder cancer. In this study we investigated the relationship among arsenic methylation ability, CAE, and the risk of bladder cancer in a hospital-based case-control study in southwestern Taiwan. From January 1996 to December 1999 we identified 49 patients with newly diagnosed cases of bladder cancer at the National Cheng-Kung University (NCKU) Medical Center; controls consisted of 224 fracture and cataract patients selected from the same medical center. The levels of four urinary arsenic species: arsenite (As(III)), arsenate (As(V)), MMA(V), and DMA(V)) were determined in all subjects by using the high-performance liquid chromatography hydride-generation atomic absorption spectrometry (HPLC-HGAAS). CAE was estimated by using published data collected in a survey from 1974 to 1976. Compared to a CAE < or = 2 mg/L-year, CAE > 12 mg/L-year was associated with an increased risk of bladder cancer (multivariate odds ratio (OR) 4.23, 95% confidence interval (CI) 1.12-16.01), in the setting of a low SMI (< or = 4.8). Compared to women, smoking men (OR 6.23, 95% CI 1.88-20.62) and non-smoking men (OR 3.25, 95% CI 0.95-11.06) had higher risks of bladder cancer. Given the same level of PMI, smoking men (OR 9.80, 95% CI 2.40-40.10) and non-smoking men (OR 4.45, 95% CI 1.00-19.84) had a higher risk of bladder cancer when compared to women. With the same level of SMI, both smoking men (OR 6.28, 95% CI 1.76-22.39) and non-smoking men (OR 3.31, 95% CI 0.84-12.97) had a higher risk of bladder cancer when compared to women. Subjects with low SMI have a substantially increased risk of bladder cancer, especially when combined with high CAE levels.

Optimization of the extraction for the determination of arsenic species in plant materials by high-performance liquid chromatography coupled with hydride generation atomic fluorescence spectrometry

A study has been conducted for the separation and the determination of arsenic species in plants using high-performance liquid chromatography–hydride generation atomic fluorescence spectrometry with emphasis on sample extraction procedures. Various extraction solvents have been applied to extract arsenic species from plants in order to investigate the uptake, transfer and accumulation processes of arsenic. The method was optimized with respect to the selection of extraction solvent, extraction time and the number of extraction steps. The analytical procedure has been validated by analyzing standard reference material GBW 82301 (peach leaves) and successfully used for the arsenic speciation in plants grown on contaminated soil near an arsenic mine. Inorganic arsenic, especially arsenate (As(V)) appears to be the major component in plants and organic arsenic species of monomethylarsenic acid and dimethylarsenic acid were detected at low concentrations.

Monitoring of arsenic exposure with speciated urinary inorganic arsenic metabolites for ion implanter maintenance engineers

For wafer fabrication in the semiconductor industry, maintenance engineers are potentially exposed to hazards during their work of disassembling machine components for cleanup. One special concern is the presence of arsenic or arsenic compounds in the working environment. This study analyzed speciated urinary inorganic arsenic metabolites of the maintenance engineers using high-performance liquid chromatography–hydride generation atomic absorption spectrometry to study the potential arsenic exposure during their maintenance work. In total, from six wafer fabrication facilities, 30 maintenance engineers were recruited as the exposed group and another 12 office-based engineers served as the control group. First morning-voided urine samples of each study subject were collected for 7 consecutive days. The levels of total urinary inorganic arsenic metabolites for the exposed group were 1.7±1.4, 1.4±1.1, 6.2±6.7, 20.2±14.1, and 29.5±17.2 μg/L for As 3+, As 5+, monomethylarsonic acid, dimethylarsinic acid, and total inorganic arsenic, respectively. Both the concentration of monomethylarsonic acid and its percentage in total urinary inorganic arsenic metabolites showed significantly ascending trends for the control group, for the engineers without preventative maintenance work prior to their urine sampling, and for the engineers with such work prior to their urine sampling ( P<0.05 and P<0.0005, respectively). The data also suggested that, at low-level occupational arsenic exposure, the concentration of total urinary inorganic arsenic metabolites might be misleading due to the confounding effect resulting from intake of seafood, such as arsenosuger. Nevertheless, monitoring of urinary arsenic species by using the percentage change of monomethylarsonic acid in total urinary inorganic arsenic metabolites as an indicator for the verification of arsenic exposure is helpful and appropriate in such cases.

Speciation analysis of arsenic in environmental solids Reference Materials by high-performance liquid chromatography–hydride generation–atomic fluorescence spectrometry following orthophosphoric acid extraction

A method for the determination of arsenic species (arsenite, arsenate, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA)) in environmental solid samples has been studied and applied to three reference materials (river sediment, agricultural soil, sewage sludge) certified for their total As content and to real world samples. The analytical method used was ion-exchange liquid chromatography coupled on-line to atomic fluorescence spectroscopy through hydride generation. It was applied to the determination of As species in orthophosphoric acid extracts of the solids; the efficiency of this extraction procedure was studied in details, as well as the stability of extracts of As-rich ones. Very low detection limits were obtained, ranging from 0.02 to 0.04 mg (As) kg −1 for all species in all matrices. This high sensitivity allows both the analysis of As-poor samples and the dilution of extracts, of As-rich ones, reducing, thus, the possibility of matrix interferences and allowing a drastic improvement of chromatograms obtained when high concentrations of extractant are used. The efficiency of orthophosphoric acid extraction was shown to depend more upon the nature of the material analysed than on acid concentration, excellent (90–100%) recoveries of total As being obtained for the sediment and the sludge reference materials samples whereas yield did not exceed 62% for the soil Reference Materials. Procedures allowing a convenient stability of As species, including As(III), in the extracts are presented. In the three Reference Materials studied As(V) was found to be the main species, As(III) being only a minor component except in sludge where it amounts to ca. one-third of total As; methylated species, MMAA and DMAA, were evidenced only in the sludge sample at low (0.2–0.3 mg (As) kg −1) concentrations. Some applications to “real world” untreated equatorial sediment or agricultural soil samples evidenced similar abundances of As(V) and As(III) as well as the presence of methylated species. On the whole, the method proposed has a very good potential as a routine speciation analysis procedure for As speciation studies in environmental solids.

Speciation of dimethylarsinic acid and monomethylarsonic acid by gas chromatography–mass spectrometry

A GC–MS method has been developed to determine two methylated arsenic species in human urine samples. This GC–MS method was compared with high-performance liquid chromatography–hydride generation–atomic fluorescence spectrometry. The yield of derivatisation for dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) using thioglycol methylate was measured. The detection limits for DMA and MMA using this GC–MS method are 0.95 and 0.8 ng/cm 3, respectively.

Speciation determination of arsenic in urine by high-performance liquid chromatography-hydride generation atomic absorption spectrometry with on-line ultraviolet photooxidation.

A coupled system for arsenic speciation determination based on high-performance liquid chromatography (HPLC), on-line UV photooxidation and continuous-flow hydride generation atomic absorption spectrometry (HGAAS) was built from commercially available modules with minor modifications to the electronic interface, the software and the gas-liquid separator. The best results were obtained with strong anion-exchange columns, Hamilton PRP X-100 and Supelcosil SAX 1, and gradient elution with phosphate buffers containing KH2PO4-K2HPO4. The on-line UV photooxidation with alkaline peroxodisulfate, 4% m/v K2S2O8-1 mol l-1 NaOH, in a PTFE knotted reactor for 93 s ensures the transformation of inorganic AsIII, monomethylarsonate, dimethylarsinate, arsenobetaine, arsenocholine, trimethylarsine oxide and tetramethylarsonium ion to arsenate. About 32-36 HPLC-UV-HGAAS runs could be performed within 8 h, with limits of detection between 2 and 6 micrograms l-1 As, depending on the species. The method was applied to the analysis of spot urine samples and certified urine reference materials (CRMs). Upon storage at 4 degrees C, reconstituted CRMs are stable for at least 2 weeks with respect to both their total arsenic content and the individual species distribution.