Methylarsonic Acid Research Articles

Arsenic speciation analysis in human urine for long term epidemiological studies: The Multi-Ethnic Study of Atherosclerosis (MESA)

Arsenic is a ubiquitous toxic metalloid causing serious health problems. Speciation analysis of arsenic in human urine provides valuable insights for large-scale epidemiological studies and informs on sources of exposure as well as human metabolism. The Multi-Ethnic Study of Atherosclerosis (MESA) is a valuable cohort for assessing chronic low-moderate arsenic exposure and health effects in an ethnically diverse US population. We present a state-of-the-art arsenic speciation analysis methodology and its application to 7677 MESA spot urine samples based on high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry. This method is fast, robust and detects a total of 11 individual As species at method detection limits of 0.02–0.03 μg arsenic/L urine for each individual species. Our analytical approach features excellent mean method accuracy (98%) and precision (5%) for the main arsenic species in urine (arsenobetaine, methylarsonic acid, dimethylarsinic acid, and total inorganic As); intra- (3–6%) and inter-day coefficients of variability (5–6%); column recovery (96 ± 7%); and spike recovery (97 ± 6%). The main arsenic species were detectable in ≥95% of urine samples due to the implementation of an oxidation step. Each individual minor arsenic species was detectable in ≤25% of all urines, although at least one of them was detected in almost half the participants. We identified two minor urinary arsenic species as dimethylarsinoylacetic acid and dimethylarsinoylpropionic acid, potential metabolites of seafood-related arsenicals. We observed differences in individual As species excretion by race/ethnicity, with Asian-American participants featuring 3–4 times higher concentrations compared to other participants. We also found differences by site, body mass index, smoking status, rice intake, and water arsenic levels, potentially indicating different exposures or related to individual bio-metabolism. The proposed approach is suitable for epidemiological studies and the collected data will constitute the base for future research on potential health effects of chronic low-level arsenic exposure.

Ecotoxicological impact of heavy metals on wild mud crabs (Scylla olivacea) in Malaysia: An integrative approach of omics, molecular docking and human risk assessment

Mud crab, one of the aquatic organisms found in estuary areas, has become a significant economic source of seafood for communities due to its delectable taste. However, they face the threat of heavy metal contamination, which may adversely affect their biological traits. This study explored the comparison of the mud crabs collected from Setiu Wetland as a reference site, while Kuala Sepetang is an area that contains a higher concentration of heavy metals than Setiu Wetlands. Heavy metal levels were quantified using inductively coupled plasma mass spectrometry (ICP-MS), while proteomes were assessed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and 1H nuclear magnetic resonance (NMR)-based metabolomics, respectively. Heavy metal contamination affects the proteome, metabolome, and putative molecular targets in mud crabs (Scylla olivacea), leading to oxidative stress. Mud crabs collected from the metal-polluted area of Kuala Sepetang in Perak had considerably elevated concentrations of nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), chromium (Cr), and cadmium (Cd) in comparison to the reference site of Setiu Wetlands in Terengganu. The proteome analysis revealed an upregulation of the stress-response protein Hsp70, which triggered superoxide dismutase (SOD) and increased arginine kinase expression (5.47 fold) in the muscle tissue, results in the alteration of metabolite regulation in the mud crab from Kuala Sepetang. Additionally, in the muscle tissues of mud crabs obtained from Kuala Sepetang, uncharacterized myosin-tail 1 domain proteins and sarcoplasmic calcium-binding proteins were downregulated. The metabolomic investigation identified changes in metabolites associated with energy metabolism and osmoregulation. Exploration of docking analysis suggests potential connections between methylarsonic acid and essential proteins in mud crabs. These findings suggest that the presence of heavy metals disrupts physiological processes and highlights potential molecular targets that warrant further investigation.

Positive Association of Urinary Dimethylarsinic Acid (DMAV) with Serum 25(OH)D in Adults Living in an Area of Water-Borne Arsenicosis in Shanxi, China.

Limited studies have demonstrated that inorganic arsenic exposure is positively associated with serum vitamin D levels, although the correlation between urinary arsenic species and serum vitamin D has not been investigated in areas of water-borne arsenicosis. A cross-sectional study of 762 participants was conducted in Wenshui Country, Shanxi Province, a water-borne arsenicosis area. The results showed a positive relationship between urinary arsenic species (inorganic arsenic (iAs), methylarsonic acid (MMAV), dimethylarsinic acid (DMAV) and serum 25(OH)D. Log-binomial regression analysis indicated a 0.4% increase in the risk of vitamin D excess for every 1-unit increment in the Box-Cox transformed urinary DMAV after adjustment for covariates. After stratifying populations by inorganic arsenic methylation metabolic capacity, serum 25(OH)D levels in the populations with iAs% above the median and primary methylation index (PMI) below the median increased by 0.064 ng/mL (95% CI: 0.032 to 0.096) for every one-unit increase in the Box-Cox transformed total arsenic (tAs) levels. Serum 25(OH)D levels increased by 0.592 ng/mL (95% CI: 0.041 to 1.143) for every one-unit rise in the Box-Cox transformed iAs levels in people with skin hyperkeratosis. Overall, our findings support a positive relationship between urinary arsenic species and serum 25(OH)D. It was recommended that those residing in regions with water-borne arsenicosis should take moderate vitamin D supplements to avoid vitamin D poisoning.

Can a 12-gene expression signature predict the cell transforming potential of tumor promoting agents in Bhas 42 cells?

To date, long-term rodent carcinogenesis assays are the only assays recognized by regulators to assess non-genotoxic carcinogens, but their reliability has been questioned. In vitro cell transformation assays (CTAs) could represent an interesting alternative to animal models as it has the advantage of detecting both genotoxic and non-genotoxic transforming chemicals. Among them, Bhas 42 CTA uses a cell line that has been transfected with the oncogenic sequence v-Ha-ras. This sequence confers an “initiated” status to these cells and makes them particularly sensitive to non-genotoxic agents. In a previous work, transcriptomic analysis revealed that the treatment of Bhas 42 cells with transforming silica (nano)particles and 12-O-tetradecanoylphorbol-13-acetate (TPA) commonly modified the expression of 12 genes involved in cell proliferation and adhesion. In the present study, we assess whether this signature would be the same for four other soluble transforming agents, i.e. mezerein, methylarsonic acid, cholic acid and quercetin. The treatment of Bhas 42 cells for 48 h with mezerein modified the expression of the 12 genes of the signature according to the same profile as that of the TPA. However, methylarsonic acid and cholic acid gave an incomplete signature with changes in the expression of only 7 and 5 genes, respectively. Finally, quercetin treatment induced no change in the expression of all genes but exhibited higher cytotoxicty. These results suggest that among the transforming agents tested, some may share similar mechanisms of action leading to cell transformation while others may activate different additional pathways involved in such cellular process. More transforming and non-transforming agents and gene markers should be tested in order to try to identify a relevant gene signature to predict the transforming potential of non-genotoxic agents.

Arsenic, cadmium, and lead in rice and rice products on the Austrian market

ABSTRACT Fifty-one rice samples, i.e. 25 rice varieties, 8 rice products, and 18 rice containing baby foods from the Austrian market were surveyed for arsenic, cadmium, and lead. Inorganic arsenic (iAs) is most toxic to human health, and its mean concentrations in rice were 120 µg kg−1, 191 µg kg−1 in rice products, and 77 µg kg−1 in baby foods. The average dimethylarsinic acid and methylarsonic acid concentrations were 56 µg kg−1 and 2 µg kg−1, respectively. The highest iAs concentration was found in rice flakes (237 ± 15 µg kg−1), close to the Maximum Level (ML) set by the EU regulation for husked rice (250 µg kg−1). The levels of cadmium (12 to 182 µg kg−1) and lead (6 to 30 µg kg−1) in the majority of rice samples were below the European ML. Upland grown rice from Austria showed both, low inorganic arsenic (<19 µg kg−1) and cadmium (<38 µg kg−1) concentrations.

Arsenic exposure induces urinary metabolome disruption in Pakistani male population

Millions of people are at risk of consuming arsenic (As) contaminated drinking water in Pakistan. The current study aimed to investigate urinary arsenic species [iAsIII, iAsV, dimethylarsinic acid (DMA), methylarsonic acid (MMA)] and their potential toxicity biomarkers (based on urinary metabolome) in order to characterize the health effects in general adult male participants (n = 588) exposed to various levels of arsenic in different floodplain areas of Pakistan. The total urinary arsenic concentration (mean; 161 μg/L) of studied participants was lower and/or comparable than those values reported from other highly contaminated regions, but exceeded the Agency for Toxic Substances and Disease Registry (ATSDR) limits. For all the participants, the most excreted species was DMA accounting for 65% of the total arsenic, followed by MMA (20%) and iAs (16%). The percentage of MMA detected in this study was higher than those of previously reported data from other countries. These results suggested that studied population might have high risk of developing arsenic exposure related adverse health outcomes. Furthermore, random forest machine learning algorithm, partial correlation and binary logistic regression analysis were performed to screen the arsenic species-related urinary metabolites. A total of thirty-eight metabolites were extracted from 2776 metabolic features and identified as the potential arsenic toxicity biomarkers. The metabolites were mainly classified into xanthines, purines, and amino acids, which provided the clues linking the arsenic exposure with oxidative stress, one-carbon metabolism, purine metabolism, caffeine metabolism and hormone metabolism. These results would be helpful to develop early health warning system in context of arsenic exposure among the general populations of Pakistan.

Metabolism of Arsenic in Human by AS3MT Gene

The AS3MT may be the most significant protein for the methylation of chemical elements species. The transfer of methyl radical from S-adenosyl-L-methionine (AdoMet) to powerfulness arsenical (AsIII) is catalyzed by the AS3MT that is critical for arsenic metabolism in humans. Since the AS3MT genetic polymorphism is linked to arsenic resistance, the association between the single ester polymorphism (SNP) and AS3MT inorganic arsenic (iAs) metabolism is being studied. Additionally, we tend to compared chemical action properties of recombinant human AS3MT and AS3MT/M287T. In reaction S-adenosylmethionine, arsenite, or methylarsonous acid (MAsIII) as substrates and endogenous reductants, together with glutathione (GSH), a thioredoxin enzyme (TR) system and tris(2-carboxyethyl) pesticide complex (TCEP). By victimization of either TR or Trx or NADPH or TCEP, AS3MT catalyzes the conversion of iAsIII to MAsIII then to methyl radical sonic acid (MAsV), dimethylarsinous acid (DMAsIII), and diethylarsinic acid (DMAsV). The Cys156 and Cys206 gift in similarity model forms the binding website for AsIII. Cys32 and Cys61 are linked by disulphidebond. The most important product in the initiative of methylation is MAsIII which remains sure to protein until it gets methylated. The product is a lot of hepatotoxic and more malignant neoplastic disease powerfulness methyl arsenicals, however, arsenic undergoes oxidation and reduction as enzyme-bound intermediates.

Dietary exposure to arsenic species in Japan in 2019 using a total diet study based on composite sample with market basket approach at the national level

To estimate the mean dietary exposure to total As (tAs) and some arsenic species [inorganic arsenic (iAs), methylarsonic acid (MMAs) and dimethylarsinic acid (DMAs), and arsenobetaine (AsB)] across the entire Japanese population (≥1 year old), a national total diet study (TDS) based on composite sample with a market-basket approach was conducted in Japan from 10 regions throughout Japan in 2019. Mean dietary exposure to iAs of 0.251 μg kg−1 day−1 showed a slightly lower value compared to the health-based guideline value of 0.30 μg kg−1 day−1. The calculated margin of exposure of 1.2–31.9 were lower or similar to the uncertainty factors of 30. Therefore, the possibility of a risk to Japanese people cannot be excluded. This study indicated that consumption of rice and rice products contributed to 64 % of the dietary exposure to iAs. Furthermore, results showed that dietary exposure to tAs had been increasing gradually since 2004, while that to iAs remained steady since 2014. These data indicate the importance of continuing to survey the dietary exposure to total As and As species.

New arsenic compound identified in rice grain: dimethylarsonyldimethylarsinic acid

Environmental context The arsenic content and its speciation in harvested rice are dependent on the genetics of the rice variety, the agricultural practise as well as the speciation of arsenic in the soil. The geochemical conditions and therefore the microbiological regime in the paddy fields can influence the biomethylation of the arsenic in the porewater and therefore can influence the extent of arsenic uptake and its speciation in rice plants.Rationale Rice is routinely monitored throughout the world for compliance with regulatory limits of inorganic arsenic. Rice grains are well known for their relatively high arsenic concentration in the form of dimethylarsinic acid, methylarsonic acid and inorganic arsenic with other arsenic containing compounds rarely occurring. During a routine survey by the US FDA, an unexpected arsenic compound was noted.Methodology The compound was eventually identified using a combination of liquid chromatography with elemental (HPLC–ICPMS) and molecular mass spectrometry (HPLC–ESMS) as well as chemical derivatisation.Results Here we report the identification of the previously unknown arsenical in rice grain, dimethylarsonyldimethylarsinic acid; its origin is unknown.

Does and duration of exposure time dependent regulation of proteins in the urinary bladder of hamsters exposed to sodium arsenite

Does and duration of exposure time dependent regulation of proteins in the urinary bladder of hamsters exposed to sodium arsenite

Exposure to Arsenic in the Air and 15-F2t-Isoprostane in Urine in a Sub-population of Inhabitants of a Copper Smelter Region

Most studies on arsenic toxicity have been conducted among populations exposed to arsenic contained in drinking water. Relatively little research concerns effects of airborne arsenic. The aim of this study was to determine whether there is an association between urinary 15-F2t-isoprostane (u15-F2t-IsoP) levels in relation to renal function (urinary creatinine and N-acetyl-β-d-glucosaminidase––uNAG) and urinary arsenic (uAs) in inhabitants from copper smelter impact zone. The secondary purpose of the analysis was to assess utility of a potential association between uAs and u15-F2t-IsoP as a biomarker of systemic oxidative stress. Urinary 15-F2t-IsoP, NAG, and creatinine were measured in 967 urine samples collected from 649 adult women (51.9 ± 13.2 years old) and 318 adult men (53.8 ± 14.9 years old). Total uAs concentration was measured in 918 samples using HPLC-ICP-MS. Arsenic species, such as inorganic arsenic, methylarsonic acid, dimethylarsinic acid, and arsenobetaine, were measured in urine collected from 255 participants with uAs exceeding the upper norm. Data were analyzed using multivariate linear regression and logistic regression models. In the studied population urinary creatinine was positively associated with uAs. A positive linear correlation (p < 0.0000) between lg(uAs) and u15-F2t-IsoP was found both for normal and elevated uAs. A positive linear correlation was observed also between lg(ΣuAs) and u15-F2t-IsoP (p < 0.0000). In the logistic regression model, after adjustment for confounders, elevated uAs was the only predictor of increased u15-F2t-IsoP (OR = 1.31, 95% CI 1.08–1.59, p < 0.01). Cigarette smoking was associated with renal proximal tubular dysfunction only in people with uNAG concentration above 75th quartile. In the studied population chronically exposed to airborne arsenic, increase in urinary arsenic is associated with renal dysfunction and systemic oxidative stress. Urinary 15-F2t-isoprostane may be useful in the monitoring of health status in populations exposed to airborne arsenic.

Origins, fate, and actions of methylated trivalent metabolites of inorganic arsenic: progress and prospects.

The toxic metalloid inorganic arsenic (iAs) is widely distributed in the environment. Chronic exposure to iAs from environmental sources has been linked to a variety of human diseases. Methylation of iAs is the primary pathway for metabolism of iAs. In humans, methylation of iAs is catalyzed by arsenic (+ 3 oxidation state) methyltransferase (AS3MT). Conversion of iAs to mono- and di-methylated species (MAs and DMAs) detoxifies iAs by increasing the rate of whole body clearance of arsenic. Interindividual differences in iAs metabolism play key roles in pathogenesis of and susceptibility to a range of disease outcomes associated with iAs exposure. These adverse health effects are in part associated with the production of methylated trivalent arsenic species, methylarsonous acid (MAsIII) and dimethylarsinous acid (DMAsIII), during AS3MT-catalyzed methylation of iAs. The formation of these metabolites activates iAs to unique forms that cause disease initiation and progression. Taken together, the current evidence suggests that methylation of iAs is a pathway for detoxification and for activation of the metalloid. Beyond this general understanding of the consequences of iAs methylation, many questions remain unanswered. Our knowledge of metabolic targets for MAsIII and DMAsIII in human cells and mechanisms for interactions between these arsenicals and targets is incomplete. Development of novel analytical methods for quantitation of MAsIII and DMAsIII in biological samples promises to address some of these gaps. Here, we summarize current knowledge of the enzymatic basis of MAsIII and DMAsIII formation, the toxic actions of these metabolites, and methods available for their detection and quantification in biomatrices. Major knowledge gaps and future research directions are also discussed.

Risks associated with the consumption of inorganic and organic arsenic

It is known that the chronic intake of arsenic (As) leads to the development of multisystem pathologies. In the case of high levels of As consumption, the risks of negative effects of exposure to inorganic and methylated forms persist for decades. The International Agency for Research on Cancer (IARC) has established that all inorganic forms of As are absolute carcinogens (group 1). Methylated forms of As are classified as substances possibly carcinogenic to humans (group 2b). Not metabolized in the human body forms of organic As are not carcinogenic to humans (group 3). The aim - assessment of health risks of various forms of As contained in food, including seafood. Material and methods. The scientific data regarding the risks associated with As contamination of food obtained by using PubMed, Web of Science, Google Scholar databases, legislative and regulatory acts of the Eurasian Economic Union, the Russian Federation, the Codex Alimentarius Commission, the European Union and other coun tries have been analyzed. Results. The analysis of the available data showed that the degree of As toxicity decreased in the following order: glutathione of dimethylarsonic acid (DMAIIIGl) > methylarsic acid (MMAIII) > dimethylarsic acid (DMAIII) > arsenic hydrocarbons (AsHC) > arsenite (AsIII) > arsenate (AsV) > trimethylarsine (TMAIII) > methylarsonic acid (MMAV) > dimethylarsonic acid (DMAV) > DMAIII-sugar glyceride > DMAV-sugar glyceride > thio compounds of DMAV > arsenosugarsIII > arsenosugarsV > tetramethylarsonium chloride (TETPA) > trimethylarsine oxide (TMAO), arsenocholine (AsC) > arsenobetaine (AB). Consequently, the toxicity of some methylated and organic forms of As (for example, DMAIIIGl, AsHC) may be higher than that of its inorganic forms. It is known that As is found in foods mainly in organic forms. When ingested with food, As organic forms are metabolized and, thus, could cause a number of negative effects in the organism. Conclusion. High levels of organic and inorganic forms of As in food, including seafood, could have a negative impact on the health of the population, which makes it necessary to conduct additional assessments of the health risks of various forms of As entering the body. The insufficient amount of data on the toxicity of organic forms of As indicates the impossibility of separate setting of safety maximum levels for organic and inorganic forms of As in foods.

Arsenic exposure and Measles Antibody Titers in the US Children: NHANES 2003-2004 and 2009-2010.

Background/Aim: Exposure to arsenic during childhood is associated with adverse health problems including cancers and non-cancerous diseases. However, little is known about its effect on vaccine-related humoral immunity in children. In this study, we examined the association between arsenic exposure and measles antibody titers in US children. Methods: The association between urinary arsenic and serum measles antibody levels in the US children aged between 6 and 11 was investigated, based on the National Health and Nutrition Examination Survey (NHANES) 2003-2004 and 2009-2010. The total urinary arsenic level was calculated by summing inorganic arsenic and their metabolites (arsenite, arsenate, methylarsonic acid, and dimethylarsinic acid), and was divided by the level of urinary creatinine. The generalized linear regression was conducted to evaluate the association, adjusted for the cycle, age, race, undergrowth, secondhand smoking, and poverty index ratio. Stratified analyses were conducted by gender and serum folate levels using the median as cutoff (18.7 ng/mL). Results: The level of serum measles antibody titers decreased by 28.1% (95%CI: −44.2%, −12.0%) per tertile increase in the concentration of creatinine-adjusted urinary arsenic among boys with serum folate levels lower than 18.7 ng/ml. However, no associations were observed in boys with high serum folate levels and girls. Conclusion: Our stratified analysis showed the inverse association between arsenic exposure and measles antibody level among boys with lower folate intake. This study will provide the basis for an intervention strategy to protect children’s health from arsenic exposure.

Inorganic arsenic-mediated upregulation of AS3MT promotes proliferation of nonsmall cell lung cancer cells by regulating cell cycle genes.

Long-term arsenic exposure can promote cancer through epigenetic mechanisms, and arsenite methyltransferase (AS3MT) plays an important role in this process. However, the expression patterns and mechanisms of AS3MT in arsenic carcinogenesis remain unclear. In this study, we found that the AS3MT was overexpressed in arsenic exposed population, non-small cell lung cancer (NSCLC) tissues, and A549 cells with sodium arsenite (NaAsO2 ) treatment for 48 hours. Besides, the level of AS3MT expression was positively correlated with the concentrations of urinary total arsenic (tAs), inorganic arsenic (iAs), methanearsonic acid (MMA), and dimethylarsinic acid (DMA) in all subjects. Functional experiments demonstrated that siRNA-mediated knockdown of AS3MT significantly inhibited proliferation of A549 cells. Mechanism investigation revealed that silencing of AS3MT inhibited proliferation by increasing mRNA expression levels of p21 and E2F1, and inhibiting CDK1, CDK2, CDK4, CDK6, Cyclin A2, Cyclin E1, Cyclin E2, and PCNA mRNA expression. Therefore, arsenic increased AS3MT expression in vivo and in vitro, which could directly act on the cell and affect the progression of NSCLC by regulating cell cycle genes.

A Simple and Effective Method for Speciation Analysis of 13 Arsenic Species Using HPLC on a Fluorocarbon Stationary Phase Coupled to ICP-MS.

The separation properties of arsenic species was investigated using HPLC-ICP-MS with several commercially available fluorocarbon stationary phases and no ion-pair reagents in HPLC. One pentafluorophenyl column showed the highest potential for the separation of a larger number of arsenic species when using simple acid-based mobile phases. After modification of the operational parameters in HPLC, the speciation analysis of 13 representative arsenic species: arsenite, arsenate, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, tetramethylarsonium, arsenobetaine, arsenocholine, thio-dimethylarsinic acid, oxo-arsenosugar-glycerol, oxo-arsenosugar-phosphate, oxo-arsenosugar-sulfonate, and oxo-arsenosugar-sulfate, was achieved by HPLC-ICP-MS with the column along with a mobile phase of 0.05% heptafluorobutyric acid-methanol (99:1, volume per volume).

Assessing inorganic arsenic in rice and its health risk to consumers in Ho Chi Minh City, Vietnam

PurposeThe consumption of rice that contains high levels of inorganic arsenic may cause human health risk. This study aims to determine As species concentrations, particularly iAs, in raw rice in Ho Chi Minh (HCM) City and its health risks.Design/methodology/approachA total of 60 polished raw composite samples of rice were purchased from traditional markets and supermarkets in HCM City. All samples were analyzed by HPLC-ICPMS for As species determination.FindingsMean concentrations of inorganic arsenic in all samples, which were purchased from supermarket and traditional market, were 88.8 µg/kg and 80.6 µg/kg, respectively. Overall, inorganic arsenic level was 84.7 µg/kg and contributed the highest proportion of arsenic species in rice with 67.7%. The proportion profiles for arsenic species were: As (III) (60 %); dimethylarsinic acid (32.2 %); As (V) (7.7 %) and methylarsonic acid (0.1 %). Inorganic arsenic level in raw rice was below the recommendation of World Health Organization. Using the benchmark dose recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), all exposure doses were lower than BMDL05. However, as the doses ranged from 3.0 to 8.6 of Margin of Exposure (MOE), the health risk of iAs from rice consumption remains public health concern.Originality/valueThe study results report on the surveillance data of the presence of inorganic arsenic in raw rice products, which are available in the supermarkets and traditional markets, and its health risk to consumers in a metropolitan city in Vietnam.

Association of dietary intake and urinary excretion of inorganic arsenic in the Japanese subjects

Quantitative relationship between intake of inorganic arsenic (iAs) and urinary excretion of iAs and its metabolite, methylarsonic acid (MMA), was investigated for 150 adult Japanese subjects. Duplicate diet was used for the determination of intake and first void of urine on the next day of duplicate diet sampling was used for urinary iAs + MMA determination. Speciation analysis of arsenic in diet and urine was carried out with liquid chromatography-inductively coupled plasma mass spectrometry. Geometric mean iAs intake of the subjects was 0.349 μg/kg/day and that of urinary iAs + MMA concentration was 5.20 ng As/mL (specific gravity (SG) corrected) or 4.05 ng As/mg creatinine (Cre). There was a significant positive correlation between iAs intake and urinary iAs + MMA concentration: the correlation coefficient between intake and Cre-corrected urinary concentration (r = 0.544) was greater than that between intake and SG-corrected concentration (r = 0.458). The regression equation of intake-excretion was: log10[dailyintake]=0.451×log10[creatininecorrectedurinaryiAs+MMA]+0.814. This equation has a practical value for converting urinary As levels, measured as a biomarker of exposure in epidemiologic study, to dietary intake levels in the future risk assessment.

Fluoroalkylamines: Novel, Highly Volatile, Fast-Equilibrating, and Electrospray Ionization-Mass Spectrometry Signal-Enhancing Cationic Ion-Interaction Reagents.

A new class of cationic ion-interaction reagents for reversed-phase chromatography is introduced in the present work. Compounds belonging to a homologous series of linear fluoroalkyl chains including trifluoroethylamine (TFEAm), pentafluoropropylamine (PFPAm), heptafluorobutylamine (HFBAm), and nonafluoropentylamine (NFPAm) were tested and compared with ammonia and triethylamine (TEA) for the separation of selected organic acids of general interest such as the herbicides glyphosate, ethephon, and fosamine and arsenic metabolites methylarsonic acid and dimethylarsinic acid as well as other compounds. Depending on the carbon and fluorine atom number, the fluoroalkylamines were shown to be effective cationic ion-interaction reagents, significantly enhancing the retention of organic acids on a C18 reversed-phase column. Contrary to the general behavior of ion-interaction reagents (a broader term than ion-pairing reagent), significant (up to 5-fold) and consistent enhancement in the electrospray ionization mass spectrometry signal (ESI-MS) was observed relative to ammonia and triethylamine. Overall, among the tested series HFBAm was found to offer the best overall properties among the tested series as it provided a good compromise between column equilibration time (ca. 25 column volumes) and retention behavior (up to a 10-fold increase in the retention factor of acids relative to ammonia) while providing the same general advantages found for the fluoroalkylamines such as fast washout times from the ESIMS system (ca. 30 min) and a 3–5-fold signal enhancement. The fluoroalkylamines are a new class of cationic ion-interaction reagents with clear advantages over the currently employed alkylamines and may revive the general interest in ion-interaction chromatography.

Is arsenic responsible for the toxicity of the hyperaccumulating mushroom Sarcosphaera coronaria?

The Violet Crown Cup, Sarcosphaera coronaria, is a rather inconspicuous mushroom, but with an interesting and unresolved mystery. In earlier days, the mushroom was considered edible, but several poisonings were reported in the early 20th century. The reason for the seemingly sporadic toxicity of S. coronaria is still unknown. One possible explanation is arsenic, since Crown Cups can take up high amounts of this element. We investigated the arsenic concentration and arsenic speciation in S. coronaria with inductively coupled plasma mass spectrometry (ICPMS) and HPLC coupled to ICPMS and found up to incredible 0.9% As (dry mass). Most of it was present as methylarsonic acid (MA), a less toxic form of this element. However, low concentrations of the highly toxic methylarsonous acid [MA (III)] were also detected. The amounts were too low to pose an acute risk for consumers, but the concentration of MA (III) significantly increased during simulated gastric digestion. We could not unambiguously identify arsenic as the toxic constituent of S. coronaria, but we demonstrated that the extremely toxic MA (III) can be formed under certain circumstances, which should be carefully investigated in future.