Concentrations Of Arsenobetaine Research Articles

Effects of Intestinal Microbiota on the Biological Transformation of Arsenic in Zebrafish: Contribution and Mechanism.

Both the gut microbiome and their host participate in arsenic (As) biotransformation, while their exact roles and mechanisms in vivo remain unclear and unquantified. In this study, as3mt-/- zebrafish were treated with tetracycline (TET, 100 mg/L) and arsenite (iAsIII) exposure for 30 days and treated with probiotic Lactobacillus rhamnosus GG (LGG, 1 × 108 cfu/g) and iAsIII exposure for 15 days, respectively. Structural equation modeling analysis revealed that the contribution rates of the intestinal microbiome to the total arsenic (tAs) and inorganic As (iAs) metabolism approached 44.0 and 18.4%, respectively. Compared with wild-type, in as3mt-/- zebrafish, microbial richness and structure were more significantly correlated with tAs and iAs, and more differential microbes and microbial metabolic pathways significantly correlated with arsenic metabolites (P < 0.05). LGG supplement influenced the microbial communities, significantly up-regulated the expressions of genes related to As biotransformation (gss and gst) in the liver, down-regulated the expressions of oxidative stress genes (sod1, sod2, and cat) in the intestine, and increased arsenobetaine concentration (P < 0.05). Therefore, gut microbiome promotes As transformation and relieves As accumulation, playing more active roles under iAs stress when the host lacks key arsenic detoxification enzymes. LGG can promote As biotransformation and relieve oxidative stress under As exposure.

Human urinary arsenic species, associated exposure determinants and potential health risks assessed in the HBM4EU Aligned Studies.

The European Joint Programme HBM4EU coordinated and advanced human biomonitoring (HBM) in Europe in order to provide science-based evidence for chemical policy development and improve chemical management. Arsenic (As) was selected as a priority substance under the HBM4EU initiative for which open, policy relevant questions like the status of exposure had to be answered. Internal exposure to inorganic arsenic (iAs), measured as Toxic Relevant Arsenic (TRA) (the sum of As(III), As(V), MMA, DMA) in urine samples of teenagers differed among the sampling sites (BEA (Spain)>Riksmaten adolescents (Sweden), ESTEBAN (France)>FLEHS IV (Belgium), SLO CRP (Slovenia)) with geometric means between 3.84 and 8.47μg/L. The ratio TRA to TRA+arsenobetaine or the ratio TRA to total arsenic varied between 0.22 and 0.49. Main exposure determinants for TRA were the consumption of rice and seafood. When all studies were combined, Pearson correlation analysis showed significant associations between all considered As species. Higher concentrations of DMA, quantitatively a major constituent of TRA, were found with increasing arsenobetaine concentrations, a marker for organic As intake, e.g. through seafood, indicating that other sources of DMA than metabolism of inorganic As exist, e.g. direct intake of DMA or via the intake of arsenosugars or -lipids. Given the lower toxicity of DMA(V) versus iAs, estimating the amount of DMA not originating from iAs, or normalizing TRA for arsenobetaine intake could be useful for estimating iAs exposure and risk. Comparing urinary TRA concentrations with formerly derived biomonitoring equivalent (BE) for non-carcinogenic effects (6.4μg/L) clearly shows that all 95th percentile exposure values in the different studies exceeded this BE. This together with the fact that cancer risk may not be excluded even at lower iAs levels, suggests a possible health concern for the general population of Europe.

Key genes for arsenobetaine synthesis in marine medaka (Oryzias melastigma) by transcriptomics

Marine fish undergo detoxification to overcome As stress, forming non-toxic metabolites arsenobetaine (AsB). Genes associated with AsB synthesis remain unknown. Therefore, in this study, we explored the key genes involved in the synthesis of AsB by transcriptomic analysis in marine medaka (Oryzias melastigma), and then screened candidate genes related to AsB synthesis. In the liver, 40 genes were up-regulated and 23 genes were down-regulated, whereas in muscle, 83 genes were up-regulated and 331 genes were down-regulated. We revealed that bhmt, mat2aa, and gstt1a can play a significant role in the glutathione and methionine metabolic pathway. These three genes can affect the conversion of arsenocholine (AsC) to AsB by the vitro gene transformation experiments of E. coli BL21(DE3). E. coli BL21-bhmt overexpressing bhmt resulted in more oxidation of precursor AsC to AsB. Furthermore, the AsB concentration was decreased after E. coli BL21 overexpressing mat2aa and gstt1a, which were down-regulated in marine medaka. Therefore, we concluded that bhmt, mat2aa, and gstt1a are involved in AsB synthesis. Overall, this is the first report on transcriptome screening and identification of key genes for AsB synthesis in marine medaka. We provided important insights to reveal the mystery of AsB synthesis in marine fish.

Associations of maternal urinary arsenic concentrations during pregnancy with childhood cognitive abilities: The HOME study.

Arsenic exposure during pregnancy may increase the risk for intellectual deficits in children, but limited data exist from prospective epidemiologic studies, particularly at low arsenic exposure levels. We investigated the association between prenatal maternal urinary arsenic concentrations and childhood cognitive abilities in the Health Outcomes and Measures of the Environment (HOME) Study. We used anion exchange chromatography coupled with inductively coupled plasma mass spectrometry detection to measure arsenic species content in pregnant women’s urine. The summation of inorganic arsenic (iAs), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) refers to . We assessed children’s cognitive function (n = 260) longitudinally at 1-, 2-, and 3-years using Bayley Scales of Infant and Toddler Development, at 5 years using Wechsler Preschool and Primary Scale of Intelligence, and at 8 years using Wechsler Intelligence Scale for Children. We observed a modest decrease in mental development index and full-scale intelligence quotient at ages 3 and 5 years with each doubling of with estimated score (ß) differences and 95% confidence interval (CI) of −1.8 from −4.1 to 0.5 and −2.5 from −5.1 to 0.0, respectively. This trend was stronger and reached statistical significance among children whose mothers had lower iAs methylation capacity and low urinary arsenobetaine concentrations. Our findings suggest that arsenic exposure levels relevant to the general US population may affect children’s cognitive abilities.

Contribution of diet and other factors for urinary concentrations of total arsenic and arsenic species: data for US children, adolescents, and adults.

A comprehensive analysis of the associations between the consumptions of 17 food products with urinary concentrations of arsenobetaine, total arsenic, arsenous acid, dimethylarsinic acid (UDMA), monomethylarsonic acid (UMMA), and total inorganic arsenic for US children aged 3-5 years (N = 439), children aged 6-11 years (N = 2139), adolescents aged 12-19 years (N = 2434), and adults aged >= 20 years (N = 10902) was conducted. Data from National Health and Nutrition Examination Survey for 2005-2016 were used for this study. Concentrations of arsenobetaine were as much as > 15 times higher among consumers of fish/shellfish than non-consumers for children aged 6-11 years, > 12 times higher for children aged 3-5 years, > 13 times higher for adolescents, and > 7 times higher for adults. Consumption of rice as opposed to non-consumption of rice was associated with as much as 36.5% higher concentrations of total arsenic, 12.7% higher concentrations of arsenous acid, 43.9% higher concentrations of UDMA, 18.2% higher concentrations of UMMA, and 14.1% higher concentrations of total inorganic arsenic. Thus, consumption of fish/shell fish and rice was associated with higher concentrations of organic/inorganic arsenic. In addition, consumption of alcohol was also found to be associated with higher concentrations of organic/inorganic arsenic. However, consumption of milk and milk products, vegetables, organ and other meats, and nutritional drinks was found to be associated with lower concentrations of organic/inorganic arsenic. Thus, while consumption of several foods is associated with higher concentrations of arsenic, there are also foods whose consumption is associated with decreased concentrations of arsenic. Further studies are needed to identify foods that may lead to decreased concentrations of arsenic and as such arsenic toxicity.

Concentrations of selected arsenic species in urine across various stages of renal function including hyperfiltration.

Data (N = 10,590) from National Health and Nutrition Examination Survey for 2005-2016 for US adults aged ≥ 20years were analyzed to study how concentrations of arsenobetaine (UAB), monomethylarsonic acid (UMMA), dimethylarsenic acid (UDMA), and total arsenic (UAS) in urine vary across the stages of renal function (RF). Data were analyzed over RF-1A (eGFR > 110mL/min/1.73m2), RF-1B (eGFR between 90 and 110mL/min/1.73m2), RF-2 (eGFR between 60 and 90mL/min/1.73m2), RF-3A (eGFR between 45 and 60mL/min/1.73m2), and RF-3B/4 (eGFR between 15 and 45mL/min/1.73m2). Adjusted geometric mean (AGM) concentrations of the total population, males, and females for UAS, UAB, and UDMA were observed to follow inverted U-shaped distributions with points of inflection located at RF-3A. For example, adjusted concentrations for the total population for UAS were 8.8, 8.8, 9.5, 11.7, and 9.6μg/L for those in RF-1A, RF-1B, RF-2, RF-3A, and RF-3B/4 respectively. While statistically significant differences were only occasionally observed, males, in general, had lower AGMs than females for UAS and UDMA, but females had lower AGMs than males for UAB. Among the various racial/ethnic groups, non-Hispanic whites had the lowest adjusted concentrations of all four arsenic variables. Adjusted levels of all four arsenic variables were observed to decrease over survey years of 2005-2006 through 2015-2016. However, statistical significance was not necessarily reached for all RF stages. Smoking was associated with reduced levels of four arsenic variables over RF-1A through RF-2. Diabetes was associated with increased levels of UMMA and UDMA at RF-2.

Associations between blood arsenic and urinary arsenic species concentrations as an exposure characterization tool

Blood arsenic has various toxicities including carcinogenicity, but urinary concentrations are often substituted to determine the exposure level. Since there is little information on the relation of urinary arsenic species to blood arsenic, the aim was to investigate relationships between blood total arsenic (T-As) and the urinary species adjusted by creatinine and specific gravity (SG). Blood and spot urine samples were collected from 109 Japanese subjects aged 18–66 years without occupational exposure. Positive correlations of blood T-As (median, 3.49 μg/L) with urinary creatinine-adjusted and SG-adjusted T-As and arsenobetaine were statistically significant and greater than those with the unadjusted ones. The magnitude of associations of blood T-As with creatinine-adjusted arsenic species was significantly larger than those with unadjusted or SG-adjusted ones. Most of the correlation coefficients among urinary arsenic species concentrations were significant in three adjustment methods, but there was not a significant correlation between monomethylarsonic acid and arsenobetaine after urinary creatinine and SG corrections. Given multiple regression analysis, plasma T-As concentrations showed significant relations to creatinine-adjusted T-As, dimethylarsinic acid, and arsenobetaine concentrations, but erythrocyte T-As did hardly reflect the variation of urinary arsenic species. In conclusion, creatinine-adjusted arsenic concentrations are suggested to be the most appropriate predictor of blood T-As; by contrast, use of the urinary unadjusted arsenic concentration may result in a misleading interpretation of inorganic arsenic toxicity because the associations between inorganic and organic arsenic species based on the unadjusted concentration were mutually close. Plasma T-As appeared to be the best indicator of low-level exposure in blood samples.

Arsenic speciation in fish on the market

Arsenic speciation in fish samples on the market was analyzed using gradient anion exchange high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICPMS) detection. Freeze-dried samples were extracted by methanol and water mixture (8:2v/v) with a high-speed Soxhlet system; the concentration of arsenobetaine (AsB), dimethylarsinic acid (DMAA), monomethylarsonic acid (MMAA), arsenate (As(V)) and arsenite (As(Ⅲ)) in the extract were then determined using HPLC-ICPMS. The method for determining arsenobetaine concentration was confirmed using standard reference material (SRM) of BCR 627 (tuna fish) and DORM-2 (dogfish muscle); recovery rates were 95 and 90%, respectively. The arsenic compounds in 60 market-ready fish muscle samples were investigated. The predominant arsenic compound found in samples was AsB. Arsenate was detected in low concentrations (ranged in 0.02-0.34 mg/kg As for fresh weight), whereas DMAA, MMAA and arsenite content were undetectable. Average AsB content in cephalopods, small fish and large fish were 5.42, 1.57 and 1.54 mg/kg As (fresh weight), respectively. The weekly intake of As was calculated based on the consumption of fish by Taiwanese residents. The calculated results demonstrated that the intake is 30.6 μg/kg (total As) body weight/week, higher than the acceptable weekly intake of 15 μg/kg body weight/week for inorganic arsenic that was suggested by WHO. However, around 87% of As in fish muscle was AsB. AsB is non-toxic and non-carcinogenic to humans, and is rapidly excreted after ingestion. Therefore, intake of fish muscle is low risk based on investigation results.

Analysis of Organoarsenic Compounds Concentration in Fish with the Newly Developed LC-MS/MS Method

Most fish contain some kinds of organoarsenic compounds. To assess the health risk for the chronic effects due to intake of these compounds, it is necessary to quantify the concentration of each chemical form, since the toxicity is difference depending on the form. We developed and validated the LC-MS/MS method to determine the concentration of monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), trimethylarsine oxide (TMAO), tetramethylarsonium (TeMA), arsenobetaine (AB), and arsenocholine (AC) in fish. Using this method, we quantified the concentration of each organoarsenic compounds and total arsenic in 50 fish samples from across 10 groups. Total arsenic concentration ranged from 0.53 to 25 mg/kg in all samples, except for in thread-sail filefish where the concentration ranged from 8.3 to 25 mg/kg. With the exception of sardines, in all samples AB was found at the highest level in relation to the total arsenic concentration. In sardines, the concentration of DMA was higher than that of AB, accounting for 16 to 24% of total arsenic. In red sea bream, concentrations of total arsenic, AB, and AC in farm-raised fish were lower than those in wild-caught fish.

Speciation transformation of arsenic in abalone viscera hydrolysate fraction: In vitro digestion and in vivo metabolism

Speciation transformation of arsenic in the abalone viscera hydrolysate fraction (AVHF) was evaluated using in vitro and in vivo methods to determine its safety given that AVHF is rich in arsenic. The dimethylarsinic acid (DMA) proportion and some free amino acid contents increased, whereas arsenobetaine (AB) proportion decreased when AVHF was digested by pepsin. However, molecular weight distribution was unchanged, and no obvious changes were found in the intestinal medium. In the single-dose experiment, the AB concentration on the mouse plasma rapidly increased, which reached up to 12.53 ng/mL in 2 h after the administration of AVHF (10 g/kg body weight) and reduced to half of the maximum at 8 h after administration. Furthermore, alanine (Ala) content in the urine of mice increased at 8 h after AVHF administration, suggesting that Ala might be chelated with arsenic and could not be absorbed well. Long-term experiments showed that AB was not accumulated in mice tissue/organ. However, some AB could be converted into DMA, which was mainly accumulated in mice hair. The in vivo experiments also suggested that the AVHF is safe as health food.

Ionomic profile and arsenic speciation in Semisulcospira cancellata, a freshwater shellfish from a mine-impacted river in China.

Freshwater aquatic environment close to cities and industrial areas is more sensitive than marine environment. The freshwater shellfish Semisulcospira cancellate was introduced as a bioindicator to monitor the heavy metal contamination in the river through ionomic profiles and arsenic speciation. The shellfish samples were collected near four cities along the Xiang River in China. The concentrations of elements including Mg, Al, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Sr, Cd, Sn, Sb, Ba, and Pb were determined using ICP-MS. Multivariate statistical analyses such as Pearson's correlation analysis and principle component analysis (PCA) were employed to identify the possible sources of the elements in the shellfish samples. Three principle components were extracted from the ionomic matrix and were associated with natural existence, biological pathways, and mining and smelting activities, respectively. The ionomic profiles of the shellfish samples were evaluated through hierarchical cluster analysis (HCA) which was exhibited in the form of heatmap. The shellfish samples were categorized according to the sampling sites with different contamination levels. Six As species including arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), and arsenocholine (AsC) were separated and quantified using HPLC-ICP-MS. The concentrations of As(III) and As(V) were linearly increased with total As concentration increasing. However, the proportion of AsB was decreased with total As while the AsB concentration was irrelevant to total As.

A feasible method for As speciation in several types of seafood by LC-ICP-MS/MS

A method for arsenic speciation in shark, shrimp, squid, oyster and scallop using liquid chromatography coupled to inductively coupled plasma triple quadrupole mass spectrometry (LC-ICP-MS/MS) was proposed. Suitable sensitivity and selectivity by LC-ICP-MS/MS were obtained using 10 mmol L−1 (NH4)2HPO4 diluted in 1% methanol (pH 8.65) as mobile phase. Recoveries from 90 to 104% for arsenobetaine (AsB), arsenite [As(III)], dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and arsenate [As(V)] were obtained for all samples. A certificated reference material was also analyzed and the sum of As species was in agreement with the total As concentration. Limits of quantification (LOQ) for AsB, As(III), DMA, MMA, and As(V) were 6, 30, 6, 12 and 26 ng g−1, respectively. Higher concentration of AsB was found in all seafood, while As(III) and DMA were found only in oyster. Arsenate was found in squid and scallops, and MMA was below the LOQ in all samples.

Abstract P5-08-11: Urinary arsenic metabolites and risk of breast cancer molecular subtypes in northern Mexican women

Abstract Background/Aim: For many years, the presence of arsenic (As) in drinking water of some areas in Northern Mexico has been a major concern. As levels have ranged from 71 to 600 μg/L. We have recently reported that women residing in Northern Mexico, with higher urinary monomethyl arsenic acid percentage (%MMA) had an increased breast cancer (BC) risk (MMA% ORQ5vs.Q1=2.63; 95%CI: 1.89, 3.66; p for trend &amp;lt;0.001) (López-Carrillo et al., 214). Breast tumor subtypes with distinctive biology and treatment responses are defined by the immunohistochemical expression of estrogen and progesterone receptors (HR) and human epidermal growth factor receptor 2 (HER2). Epidemiological evidence suggests that BC risk factors (i.e. breastfeeding, parity, menarche, etc.) may vary by tumor pathology.We assessed if %MMA is associated with a particular BC molecular subtype. Methods: A population based case–control study was performed from 2007 to 2011 in five states of Northern Mexico. Incident cases were identified from main public tertiary hospitals in the study area. A total of 499 patients with histopathologically confirmed BC and molecular subtype status available information were identified. Controls were healthy women, with no history of cancer, matched 1:1 by age. Tumor marker information for estrogen receptor (ER), progesterone receptor (PR) and HER2 was obtained from medical records. ER+ and PR+ was based on &amp;gt;=1% cell staining. HER2+ status was determined when at least 30% of protein overexpression was observed in the tumor cell. Cases were assigned to one of three tumor marker categories: HR+ (ER+ and/or PR+ and HER2-), HER+ (regardless of ER or PR status) and TNBC (ER-, PR-, and HER2-). Urinary concentrations (μg/L) of species As3+, As5+, MMA5+, DMA5+, and arsenobetaine (AsB) were determined by high-performance liquid chromatography ICP-MS. Detection limits were As3+: 0.12; As5+: 0.20; MMA5+: 0.12; DMA5+: 0.08; AsB: 0.08. Results were reported by g of creatinine. Total As was calculated by using both the sum of iAs, MMA, DMA plus or minus AsB concentration (TAs or TAs-AsB, respectively). iAs was calculated as the sum of trivalent (As3+) and pentavalent (As5+). %iAs, %MMA and %DMA species were estimated using TAs-AsB as denominator. Using logistic regression models, the associations between BC molecular subtypes and MMA% and DMA% was estimated according to the observed quintile distribution among controls. Based on the median value of each quintile a lineal trend was assessed accordingly. Results.The mean age of cases and controls was around 54 years with 51 years of residence in the study zone. In the entire population, TAs ranged from 0.47 to 303.29 μg/L (0.45 to 1683.83 μg/g creatinine). HR+ BC patients were 57%, HER2 23% and TNBC 20%. These figures are similar to those reported among other groups of Mexican cancer patients. After controlling by key BC factors, %MMA remained as a significant risk factor for BC only for HR+. HER2+ and TNBC tumors were not significantly associated with urinary As metabolites. Conclusion: Our results suggest that increased BC risk related to As exposure is not mediated by HER2 expression. This is the first report on As exposure and breast cancer subtypes which requires further confirmation. Citation Format: López-Carrillo L, Gamboa-Loira B, Cebrián ME. Urinary arsenic metabolites and risk of breast cancer molecular subtypes in northern Mexican women [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-08-11.

Comparative contribution of trophic transfer and biotransformation on arsenobetaine bioaccumulation in two marine fish

Marine fish can accumulate high arsenic (As) concentrations, with arsenobetaine (AsB) as the major species in the body. However, whether the high AsB accumulation in fish occurs mainly through trophic transfer from diet or biotransformation in the fish body remains unclear. This study investigated the trophic transfer and biotransformation of As in two marine fish (seabream Acanthopagrus schlegeli and grunt Terapon jarbua) fed artificial and clam diets for 28 d. The different diets contained different proportions of inorganic [As(III) and As(V)] and organic [methylarsenate (MMA), dimethylarsenate (DMA), and AsB] As compounds. Positive correlations were observed between the accumulated As concentrations and AsB concentrations in both fish, suggesting that AsB contributed to the accumulation of total As in marine fish. Based on the calculated total input of AsB and detected AsB concentrations in the muscle of the seabream and grunt, the ingested amounts of AsB accounted for 0.1–0.3%, 8.1–14.4% of detected AsB concentrations, respectively, in the muscle of seabream and grunt fish species, suggesting that AsB was mainly biotransformed versus trophically transferred in these marine fish. In summary, this study demonstrates that marine fish prefer to biotransform inorganic As forms into AsB, resulting in high bioaccumulation of total As.

Development And Validation Of A Biomarker To Estimate Inorganic Arsenic Exposure In Populations With High Seafood Intake: Evidence From The Multi-Ethnic Study Of Atherosclerosis (MESA) And The National Health And Nutrition Examination Survey (NHANES)

Introduction: In populations with low seafood intake, the sum of inorganic (iAs) and methylated (methylarsonate [MMA] and dimethylarsinate [DMA]) arsenic species (ƩAs) is used as the biomarker of iAs exposure. However, with moderate to high seafood intake, iAs exposure assessment is difficult as some seafood arsenicals contribute to DMA and maybe to MMA. We developed and validated a biomarker to estimate iAs exposure in populations with common seafood intake. Methods: The model was developed for ƩAs and individual species in 310 randomly selected MESA participants in 6 US cities and validated for DMA in 2,010 NHANES 2003-2006 participants (representative sample of US adults). We imputed urinary concentrations of iAs, DMA, MMA and ƩAs by regressing the original concentrations by arsenobetaine concentrations and extracting model residuals. To confirm that imputed biomarkers no longer reflected seafood intake but reflected exposure to iAs exposure, we estimated ratios of the geometric means of urinary arsenic with seafood and rice intake, respectively. Results: In MESA, median (IQR) for ƩAs was 8.1 (3.8, 15.5) and 7.5 (4.2, 13.2) µg/L before and after imputation, respectively. Compared to participants reporting rare/never seafood intake, those reporting more frequent seafood intake had higher concentrations for all the original urinary arsenic biomarkers. Using the imputed biomarkers, self-reported seafood intake or estimated n-3 fatty acids were no longer associated with urinary arsenic measures in MESA; self-reported intake of rice remained associated with our imputed arsenic biomarkers. In NHANES, the association between urinary DMA concentrations with self-reported seafood intake and estimated n-3 fatty acids practically disappeared with imputation. Conclusions: Correction for seafood exposure using the biomarker arsenobetaine can facilitate research about low-moderate levels of iAs exposure through water and food in general populations with frequent seafood intake.

Direct solid sample analysis with graphite furnace atomic absorption spectrometry—A fast and reliable screening procedure for the determination of inorganic arsenic in fish and seafood

Direct solid sample analysis with graphite furnace atomic absorption spectrometry (SS-GF AAS) was investigated initially with the intention of developing a method for the determination of total As in fish and other seafood. A mixture of 0.1% Pd+0.06% Mg+0.06% Triton X-100 was used as the chemical modifier, added in solution over the solid samples, making possible the use of pyrolysis and atomization temperatures of 1200°C and 2400°C, respectively. The sample mass had to be limited to 0.25mg, as the integrated absorbance did not increase further with increasing sample mass. Nevertheless, the recovery of As from several certified reference materials was of the order of 50% lower than the certified value. Strong molecular absorption due to the phosphorus monoxide molecule (PO) was observed with high-resolution continuum source AAS (HR CS AAS), which, however, did not cause any spectral interference. A microwave-assisted digestion with HNO3/H2O2 was also investigated to solve the problem; however, the results obtained for several certified reference materials were statistically not different from those found with direct SS-GF AAS. Accurate values were obtained using inductively coupled plasma mass spectrometry (ICP-MS) to analyze the digested samples, which suggested that organic As compounds are responsible for the low recoveries. HPLC–ICP-MS was used to determine the arsenobetaine (AB) concentration. Accurate results that were not different from the certified values were obtained when the AB concentration was added to the As concentration found by SS-GF AAS for most certified reference materials (CRM) and samples, suggesting that SS-GF AAS could be used as a fast screening procedure for inorganic As determination in fish and seafood.

Method for Speciation of Organoarsenic in Mussels by Liquid Chromatography Coupled to Electrospray Ionization and QTRAP Tandem Mass Spectrometry

Arsenic toxicity to humans critically depends on the chemical form of the arsenic. The Expert Committee of the Food and Agriculture Organization and the World Health Organization defined a tolerable intake only for inorganic arsenic, although the toxicity of some organoarsenic compounds is known. Arsenobetaine (AsB), arsenocholine (AsC), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) are abundant in shellfish. We present a fast and reliable method for identification of the type of organic arsenic in mussels by using liquid chromatography coupled to electrospray ionization tandem mass spectrometry on triple quadrupole with parallel determination of total arsenic by atomic absorption spectrophotometry. The method was validated by evaluating mean recoveries, repeatability, specificity, limits of quantification, and limits of detection that produced satisfactory results. The method was used to carry out the first survey of the concentrations of AsB, AsC, MMA, and DMA in seafood from southern Italy. Total As concentrations ranged from 1.38 to 12.79 mg/kg. AsB and DMA were detected in all samples (AsB: 0.72 to 10.36 mg/kg; DMA: 0.28 to 1.08 mg/kg), and concentrations of AsC and MMA ranged from 0.20 to 1.53 mg/kg. This method allowed us to rapidly and inexpensively identify arsenic types in fishery products and would be suitable for routine detection of organoarsenic compounds in molluscs.

Speciated urinary arsenic as a biomarker of dietary exposure to inorganic arsenic in residents living in high-arsenic areas in Latium, Italy

Current knowledge indicates that total urinary arsenic is not a suitable biomarker of exposure to toxic, i.e., inorganic, arsenic (iAs), whereas measurement of iAs and its methylated metabolites in urine using speciation analysis provides much more reliable estimates of exposure. The relative proportions of urinary iAs, monomethylarsonate (MA), and dimethylarsinate (DMA) can be used as a measure of methylation capacity, provided that there are no confounding factors such as consumption of food rich in DMA or containing As compounds metabolized to DMA.We analyzed by gradient elution anion-exchange HPLC-ICP-MS (high-performance liquid chromatography-inductively coupled plasma-mass spectrometry) urine samples from 153 residents in Latium (central Italy) chronically exposed to iAs via water and food. Excluding 26 subjects that excreted high concentrations of arsenobetaine (AB) (≥50 μg As/L) due to seafood consumption, iAs and related metabolites summed up about 75 % of total urinary As as measured by ICP-MS. AB and other organoarsenic compounds were detected at low concentrations in all urine samples. Considering all subjects, the sum of iAs and metabolites ranged 2–72 μg/L and relative proportions were iAs 14 %, MA 13 %, and DMA 72 % (median values), with a wide individual variability.In addition to the above arsenocompounds, the analytical method used in this study enabled the detection of dimethylthioarsinic acid (DMTA), which was found to be present in 33 % of the samples at concentrations ranging mostly from trace amounts to ~6 μg As/L. We found that part of the certified DMA content of human urine reference material SRM 2669 was present as DMTA. Four unknown arsenicals were also detected as minor species in a small proportion of samples.

The influence of diet on intra and inter-individual variability of urinary excretion of arsenic species in Italian healthy individuals

To study the effect of eating foods with a high arsenic (As) content on the intra and inter-individual variability of urinary concentrations of the As species, daily urine samples were collected for 10 consecutive days from 12 healthy male subjects. A daily food diary was kept throughout the study period. Personal exposure to airborne As was measured once during the study. As3, As5, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine were determined in all urine samples by inductive coupled plasma mass spectrometry, and the sum of As3+As5+MMA+DMA (iAs) by hydride generation-atomic absorption spectrophotometry. Exposure to airborne As was below the limit of detection in all samplings. As3 was found in only 19.2% and As5 in only 3.3% of the urine samples, whereas high urinary concentrations of arsenobetaine were observed. With the exception of arsenobetaine, expressed as a percentage, a significant inter-individual variability was observed for all species of As, for iAs and for the MMA/DMA ratio (p<0.001). Instead, the intra-individual variability was significant only for the MMA/DMA ratio (p<0.001). Among foods with a high As content, only a heavy consumption of seafood was shown to influence inter-individual variability of DMA%, arsenobetaine expressed as μgg−1 creatinine and iAs. In conclusion, even in populations with a high intake of organic As through foods, the finding of a significant inter-individual but no significant intra-individual variability of urinary species confirms the usefulness of urinary As speciation for biological monitoring of exposure to As.

Non-chromatographic screening procedure for arsenic speciation analysis in fish-based baby foods by using electrothermal atomic absorption spectrometry

A procedure for the speciation analysis of arsenic in fish-based baby foods is presented. Inorganic arsenic, methylarsonic acid (MA), dimethylarsinic acid (DMA) and arsenobetaine (AB) were determined by electrothermal atomic absorption spectrometry (ETAAS) using suspensions prepared in a 0.01 mol L −1 tetramethylammonium hydroxide (TMAH) solution. Speciation is based on the use of three different chemically modified ETAAS atomizers to obtain the analytical signals. Using a palladium salt as the chemical modifier, the signal corresponding to the total arsenic concentration is obtained. When palladium is replaced by Ce(IV), the signal is solely due to inorganic arsenic (III and V) + MA. If no signal is obtained in this latter case, it is possible to distinguish between DMA and AB using a zirconium coated atomizer. The signal obtained in this way is due solely to DMA, and the concentration of AB can be obtained by the difference with the total arsenic content. Determinations by ETAAS require the use of the standard additions method. The limits of detection for the determination of AB, DMA and inorganic arsenic (+MA) are 15, 25 and 50 ng g −1 expressed as arsenic, respectively. These detection limits are good enough for the procedure to be appropriate for the rapid determination of these compounds, avoiding extraction processes and/or chromatographic separations. Data for commercial samples, as well as for four standard reference materials, are given.