Arsenic Species In Urine Samples Research Articles

Clinimetallomics: Arsenic Speciation in Urine from Patients With Arsenism by HPLC-ICP-MS

Clinimetallomics is proposed as a branch of metallomics that focuses on the study of the metallome in clinical samples of urine, blood, and tissues. As the clinical diagnosis of arsenic poisoning is mainly based on the concentration of total arsenic in urine, the toxicity of arsenic varies greatly in different speciation. Analysis of arsenic speciation with excessive total arsenic in urine can provide a basis for precise treatment. It can also be used to understand the fate of arsenic in the body of patients with arsenic poisoning after treatment with sodium dimercaptopropane sulfonate. In this study, a HPLC-ICP-MS method was established for the determination of arsenic species in urine samples from patients diagnosed with arsenism. Use the established method to detect urine samples, which can be directly assayed after simple sample dilution with 20 mmol/L EDTA-2Na. With the concentration of arsenic speciation in the range of 1.0~100.0 ng/mL, the linear correlation coefficient was higher than 0.99996. The recoveries were between 92.4% and 109.0%. The precision of the concentration and retention time (n = 3) were less than 3.0% and 0.3%, respectively, and the detection limit was between 1.42 ng/mL and 1.86 ng/mL. This method can be applied to arsenic speciation in the urine of healthy people, in patients treated for arsenic poisoning, and in patients diagnosed with arsenism.

Low-level inorganic arsenic exposure and neuropsychological functioning in American Indian elders

BackgroundInorganic arsenic at high and prolonged doses is highly neurotoxic. Few studies have evaluated whether long-term, low-level arsenic exposure is associated with neuropsychological functioning in adults. ObjectivesTo investigate the association between long-term, low-level inorganic arsenic exposure and neuropsychological functioning among American Indians aged 64–95. MethodsWe assessed 928 participants in the Strong Heart Study by using data on arsenic species in urine samples collected at baseline (1989–1991) and results of standardized tests of global cognition, executive functioning, verbal learning and memory, fine motor functioning, and speed of mental processing administered during comprehensive follow-up evaluations in 2009–2013. We calculated the difference in neuropsychological functioning for a 10% increase in urinary arsenic with adjustment for sex, age, education, and study site. ResultsThe sum of inorganic and methylated arsenic species (∑As) in urine was associated with limited fine motor functioning and processing speed. A 10% increase in ∑As was associated with a .10 (95% CI −.20, −.01) decrease on the Finger Tapping Test for the dominant hand and a .13 decrease (95% CI −.21, −.04) for the non-dominant hand. Similarly, a 10% increase in ∑As was associated with a .15 (95% CI −.29, .00) decrease on the Wechsler Adult Intelligence Scale–Fourth Edition Coding Subtest. ∑As was not associated with other neuropsychological functions. ConclusionsFindings indicate an adverse association between increased urinary arsenic fine motor functioning and processing speed, but not with other neuropsychological functioning, among elderly American Indians.

Determination of Arsenic Species in Urine Samples of Subjects Not Exposed to Dietary Arsenic by High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry

Arsenic (As) speciation in human urine was performed by anion exchange chromatography (AEC), followed by inductively coupled plasma mass spectrometry detection (ICP-MS). Separation of arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid [MMA(V)L dimethylarsinic acid [DMA(V], arsenobetaine (AsB), and arsenocholine (AsC) in urine samples was accomplished in 9 minutes, resulting in quantification limits within the 0.3-0.9 ug L-1 range. The gradient elution program comprises two different mobile phases consisting of ultrapure water (phase A) and aqueous 20 mM nitric acid (phase B), both modified with 2% (v/v) methanol. Sample pre-treatment is based on human urine centrifugation (5000 rpm, 10 min), followed by filtration (0.45 μm) and dilution (1:4) with ultrapure water. Relative standard deviations (N=l 1) of the overall procedure were 8% for AsB and DMA(V), 11% for As(III), and 9% for MMA(V), As(V), and AsC. Arsenics quantification was performed using the standard addition method covering arsenic concentration ranges of 0-100 μ L-1 (expressed as arsenic) for all species. Germanium (5 μg L-1) was used as an internal standard. Analytical recoveries from the anion exchange column varied from 94 to 101% (urine sample spiked with low target concentrations), from 99-103% (urine sample spiked with intermediate target concentrations), and from 97-103% (urine sample spiked with high target concentrations). The developed procedure has been tested by analyzing the certified reference material NIST CRM 2669 Arsenic Species in Frozen Human Urine which offers certified contents for all arsenic species. After AEC and mass spectrometry detection, MMA(V), DMA(V), AsB, AsC, and also tetramethylarsonium ion (TETRA) were identified in several urine samples. The method has been applied to assess arsenic speciation in several human urine samples collected from volunteers not chronically exposed to arsenic via water and food.

Low-level determination of six arsenic species in urine by High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICP-MS).

Many methods that have been used to speciate arsenic metabolites in urine are unable to adequately resolve the chromatographic peaks for arsenite (As[iii]) and arsenobetaine (AsB). We present a High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICP-MS) method that has been optimized to reliably measure the following six arsenic species in human urine: As[iii], arsenate (As[v]), monomethylarsonous acid (MMA[iii]), monomethylarsonic acid (MMA[v]), dimethylarsinic acid (DMA[v]) and AsB. The method was evaluated with regards to changes in mobile phase, accuracy and precision. The ability to quantify the six species in a given sample depended on the low detection limits of the method-0.06 μg L-1 for AsB, 0.11 μg L-1 for As[iii], 0.08 μg L-1 for DMA[v], 0.12 μg L-1 for MMA[v] and 0.15 μg L-1 for As[v]. The procedure was used to measure the six arsenic species in urine samples from 387 individuals in southeast Michigan who are chronically exposed to slightly elevated levels of arsenic in their drinking water. The DMA[v] was detected in 99.2% of samples, AsB in 98.2%, MMA[v] in 73.4%, As[iii] in 45.0%, and As[v] in 27.1%. No MMA[iii] was detected even in samples analyzed within 6 hours after collection. The results raise some doubt as to whether MMA[iii] is a significant metabolite in urine of people exposed to arsenic concentrations below 20 μg L-1 in their drinking water.

Comparison of different medical cases in urinary arsenic speciation by fast HPLC–ICP-MS

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

Thio-dimethylarsinate is a common metabolite in urine samples from arsenic-exposed women in Bangladesh

Over the last 6 years, much work on arsenic species in urine samples has been directed toward the determination of the reduced dimethylated arsenic species, DMA(III), because of its high toxicity and perceived key role in the metabolism of inorganic arsenic. Recent work, however, has suggested that DMA(III) may at times have been misidentified because its chromatographic properties can be similar to those of thio-dimethylarsinate (thio-DMA). We analyzed by HPLC–ICPMS (inductively coupled plasma mass spectrometry) urine samples from 75 arsenic-exposed women from Bangladesh with total arsenic concentrations ranging from 8 to 1034 μg As/L and found that thio-DMA was present in 44% of the samples at concentrations ranging mostly from trace amounts to 24 μg As/L (one sample contained 123 μg As/L). Cytotoxicity testing with HepG2 cells derived from human hepatocarcinoma indicated that thio-DMA was about 10-fold more cytotoxic than dimethylarsinate (DMA). The widespread occurrence of thio-DMA in urine from these arsenic-exposed women suggests that this arsenical may also be present in other urine samples and has so far escaped detection. The work highlights the need for analytical methods providing specific determinations of arsenic compounds in future studies on arsenic metabolism and toxicology.

Arsenic speciation analysis of human urine using ion exchange chromatography coupled to inductively coupled plasma mass spectrometry

A sensitive and robust method for the determination of seven inorganic and organic arsenic species was developed using ion exchange chromatography combined with inductively coupled plasma mass spectrometry (IC-ICP-MS). Both anion and cation exchange columns were used in a complementary fashion. Arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) were selectively separated by an anion exchange column using sodium hydroxide (NaOH) gradient elution, while monomethylarsonous acid (MMA(III)), dimethylarsinous acid (DMA(III)) and arsenobetaine (AsB) were separated by a cation exchange column using 70 mM nitric acid as the mobile phase. Baseline separation, high repeatability and low detection limits (0.10–0.75 ng mL −1) were achieved. The spiked urine samples were analyzed with this method to evaluate the matrix effect on the method. The results suggest 1–10 dilutions should be made to urine samples before sample injection for the anion exchange analysis to minimize the matrix effect. To validate the method, a new standard reference material (NIST SRM-2670a) was also analyzed. The arsenic species in NIST SRM-2670a were determined by this method, and the sum of their concentrations agreed well with the total arsenic content certified for NIST SRM-2670a. Moreover, this method was applied to measure arsenic species in urine samples from one subject living in New Jersey who drank well water contaminated with arsenic. By this method, two key arsenic metabolites, MMA(III) and DMA(III), were found to be present in these urine samples, which has previously been rarely reported.

Speciation of Arsenic Compounds in Urine from Occupationally Unexposed and Exposed Persons in the U.K. Using a Routine LC-ICP-MS Method

This paper describes a routine, robust, and reproducible liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) speciation method for five arsenic compounds [arsenobetaine (AB), arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)] in urine. Concentrations of these arsenic species in urine samples are reported in two sets of non-occupationally exposed controls with one set having consumed fish within 24 h (n = 31) and the other not having consumed fish for 48 h (n = 34). Arsenic species in urine samples from workers in both the timber treatment industry (n = 49) and semiconductor industry (n = 46) are also reported. The arsenic content in all of the samples was also determined using hydride-generation coupled with ICP-MS. The results show that urine samples from people not occupationally exposed to arsenic contain low levels of DMA, MMA, and AB and that only urine from smokers contained any inorganic arsenic. Consumption of seafood was seen to significantly increase the levels of AB and DMA in the unexposed persons. Urine samples from the semiconductor workers exhibited significantly higher levels of arsenite, arsenate, and DMA than the unexposed samples. The urine samples from timber treatment workers exhibited significantly higher levels of four arsenic species (not AB) than those observed in both the control groups and the semi-conductor workers.

Arsenic on the Hands of Children: Wang et al. Respond

In our study of arsenic on children’s hands (Kwon et al. 2004), we measured arsenic in water samples in which participating children washed both hands after playing on selected playgrounds. The hand-washing water was filtered, and the soluble arsenic concentration in the filtrate was determined by inductively coupled plasma mass spectrometry. In response to Kissel’s comment that we did not measure insoluble arsenic, we analyzed the arsenic levels in the insoluble residue collected on the filter and summarized the unpublished data here. Results from the analysis of 64 samples from the CCA playgrounds and another 63 samples from the non-CCA playgrounds are available upon request. The total amount of arsenic in the insoluble residue collected in the hand-washing water of 64 children from the eight CCA playgrounds was 418 ± 601 ng (mean ±SD), compared to 172 ± 278 ng in the hand-washing water of 63 children from the eight non-CCA playgrounds. The total arsenic collected in the hand-washing water (insoluble arsenic on the filter plus water-soluble arsenic in the filtrate) was 934 ± 940 ng for the CCA playground and 265 ± 311 ng for the non-CCA playgrounds. The maximum amount of total arsenic collected from children’s hands was 4,743 ng (4.7 μg). This is compared with the 3.9 μg that we reported previously (Kwon et al. 2004). To provide a perspective of relative contribution of this amount of arsenic to the overall exposure to arsenic, in our article (Kwon et al. 2004) we included references for the average daily dietary ingestion of total arsenic: 38 μg (15 μg for children 1–4 years of age) for Canada (Dabeka et al. 1993), 62 μg for the United States (Gartrell et al. [1985]), 89 μg for the United Kingdom (Food Additives and Contaminants Committee 1984), 55 μg for New Zealand (Dick et al. 1978), and 160–280 μg for Japan (Tsuda et al. 1995). A range of arsenic species that have different toxicities may be present in food (Le et al. 2004). Estimated daily dietary intake of inorganic arsenic was 8.3–14 μg in the United States (Yost et al. 1998), 4.8–12.7 μg in Canada (Yost et al. 1998), and 15–211 μg in Taiwan (Schoof et al. 1998). We did not monitor children’s hand-to-mouth activity because this behavior has already been documented in the literature (Reed et al. 1999; Tulve et al. 2002). Our intent was to provide direct measurements of the amount of arsenic on children’s hands. We recognize the importance of these other studies, as we pointed out in our “Conclusions” (Kwon et al. 2004): The results—along with other information, such as the frequency and habit of hand-to-mouth activity, efficiency of transfer of arsenic from hands to mouth, and repeated contact of hands with CCA-treated wood surface after hand-to-mouth activity—are useful for assessing children’s exposure to arsenic. We have measured arsenic in sequential hand-washings and found that most arsenic was present in the first hand-washing (unpublished data). Results of arsenic in hand-washings of three children before and after playing on a CCA playground are available upon request. The amount of arsenic in the second washing was < 10% of that in the first washing, suggesting that the arsenic on children’s hands is readily washed off with water. Therefore, we conclude that children should “wash their hands after playing to reduce their potential exposure to arsenic” (Kwon et al. 2004). Biomonitoring of arsenic species in urine samples from children who play on CCA-treated structures and children who do not could be useful if the ingestion of arsenic from dietary sources would not be a major confounder.

Identification of dimethylarsinous and monomethylarsonous acids in human urine of the arsenic-affected areas in West Bengal, India.

A speciation technique for arsenic has been developed using an anion-exchange high-performance liquid chromatography/inductively coupled argon plasma mass spectrometer (HPLC/ICP MS). Under optimized conditions, eight arsenic species [arsenocholine, arsenobetaine, dimethylarsinic acid (DMA(V)), dimethylarsinous acid (DMA(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)), arsenite (As(III)), and arsenate (As(V))] can be separated with isocratic elution within 10 min. The detection limit of arsenic compounds was 0.14-0.33 microg/L. To validate the method, Standard Reference Material in freeze-dried urine, SRM-2670, containing both normal and elevated levels of arsenic was analyzed. The method was applied to determine arsenic species in urine samples from three arsenic-affected districts of West Bengal, India. Both DMA(III) and MMA(III) were detected directly (i.e., without any prechemical treatment) for the first time in the urine of some humans exposed to inorganic arsenic through their drinking water. Of 428 subjects, MMA(III) was found in 48% and DMA(III) in 72%. Our results indicate the following. (1) Since MMA(III) and DMA(III) are more toxic than inorganic arsenic, it is essential to re-evaluate the hypothesis that methylation is the detoxification pathway for inorganic arsenic. (2) Since MMA(V) reductase with glutathione (GSH) is responsible for conversion of MMA(V) to MMA(III) in vivo, is DMA(V) reductase with GSH responsible for conversion of DMA(V) to DMA(III) in vivo? (3) Since DMA(III) forms iron-dependent reactive oxygen species (ROS) which causes DNA damage in vivo, DMA(III) may be responsible for arsenic carcinogenesis in human.

High performance liquid chromatography inductively coupled plasma mass spectrometry for speciation of arsenic compounds in urine

Speciation of urinary arsenic is very important to know the extent of human exposure to inorganic arsenic and also from toxicity point of view. A high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) system for speciation of arsenite, arsenate, monomethyl arsonic acid (MMAA), dimethyl arsenic acid (DMAA) and arsenobetaine (AB) in a single run in urine samples has been developed. The method is based on anion exchange high performance liquid chromatography (HPLC) coupled on-line to inductively coupled plasma mass spectrometer (ICP-MS). Detection limits for the five arsenic species in urine samples are between 0.01 and 0.04 μg l −1. To validate the method, Standard Reference Material, toxic metals in freeze-dried urine SRM 2670 containing both normal and elevated levels of arsenic have been analyzed for arsenic species. Our results of arsenic species in Standard Reference Material SRM 2670 have been compared with the results of seven other laboratories. The method has been applied to determine the arsenic species in urine samples of two groups of people from two arsenic-affected villages of two districts, out of the nine affected districts of West Bengal, India. These two groups were using arsenic-contaminated water a few years ago, but are now supposed to be using safe water for drinking and cooking, as safe sources have been installed. From their urine speciation, the nature of exposure of individuals to arsenic compound could be predicted. It is concluded that, even though these groups are using safe water, they cannot avoid, from time to time, arsenic contamination as many water sources of the surrounding areas are arsenic contaminated.

Determination of arsenic species in human urine using HPLC with on-line photooxidation or microwave-assisted oxidation combined with flow-injection HG-AAS

An improved analytical procedure is presented for the separation and simultaneous determination of hydride-forming (toxic) and not hydride-forming (non-toxic) arsenic species in human urine. Separation was performed by cation-exchange chromatography using a new solid phase type based on the continuous bed chromatography (CBC) technology. This column permits by a factor of 4 higher flow rates than conventional columns resulting in a drastical reduction of retention times without any loss of resolution. Using this type of column, arsenobetaine (AsBet), arsenocholine (AsChol), and dimethylarsinic acid (DMA) were separated from the more toxic arsenic species arsenous acid (As(III)), arsenic acid (As(V)), and methylarsonic acid (MA) within only 4 min. The HPLC system was coupled via a flow injection system and either a UV or a microwave (MW) reactor to the HG-AAS instrument. UV photolysis and MW digestion were used to transform AsBet and AsChol to hydride-forming species and to make them accessible to HG-AAS. UV photolysis turned out to be more suitable for this application than MW digestion, because the latter technique led to peak broadening and poorer performance. The described procedure was applied to the determination of arsenic species in urine samples of non-occupationally exposed persons before and 12 h after seafood consumption. Detection limits were about 1 μg/L for each arsenic species. After consumption, the AsBet and DMA excretion increased by at least a factor of 150 for AsBet and by a factor of 6 for DMA, respectively, while the excretion of the other species did not increase significantly. This invalidates the use of total urinary arsenic as well as total hydride-forming arsenic as an indicator for exposure to inorganic arsenic.

Speciation of arsenic compounds in urine by LC-ICP MS

The method validation for the speciation of five arsenic species in urine samples by liquid chromatography hyphenated to inductively coupled plasma mass spectrometry is described. Arsenic species which are identified and quantified in urine samples are the anions of arsenic(III), arsenic(V), monomethylarsonic acid and dimethylarsinic acid, and the cationic arsenobetaine. Detection limits were obtained in the range 0.3–0.4 μg As l−1 while the repeatability was in the range 3–4% (RSD) for concentrations above five times the detection limit. Urine samples could be analysed directly after a ten-fold dilution step. Arsenic compound concentrations were determined in urine samples from a volunteer who consumed a portion of tuna fish high in arsenobetaine. It was found that arsenobetaine was excreted rapidly via the urine with maximum concentrations after 12 h. Nearly complete arsenobetaine excretion was reached after 48 h. Background levels of arsenic compounds were determined in 61 urine samples from non-exposed inhabitants of The Netherlands. © 1998 John Wiley & Sons, Ltd.

Effect of arsenosugar ingestion on urinary arsenic speciation

We developed and evaluated a method for the determination of microgram/L concentrations of individual arsenic species in urine samples. We have mainly studied arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMAA), and dimethylarsinic acid (DMAA) because these are the most commonly used biomarkers of exposure by the general population to inorganic arsenic and because of concerns over these arsenic species on their toxicity and carcinogenicity. We have also detected five unidentified urinary arsenic species resulting from the metabolism of arsenosugars. We combined ion pair liquid chromatography with on-line hydride generation and subsequent atomic fluorescence detection (HPLC/HGAFS). Detection limits, determined as three times the standard deviation of the baseline noise, are 0.8, 1.2, 0.7, and 1.0 mu/L arsenic for arsenite, arsenate, MMAA, and DMAA, respectively. These correspond to 16, 24, 14, and 20 pg of arsenic, respectively, for a 20-muL sample injected for analysis. The excellent detection limit enabled us to determine trace concentrations of arsenic species in urine samples from healthy subjects who did not have excess exposure to arsenic. There was no need for any sample pretreatment step. We used Standard Reference Materials, containing both normal and increased concentrations of arsenic, to validate the method. Interlaboratory studies with independent techniques also confirmed the results obtained with the HPLC/HGAFS method. We demonstrated an application of the method to the determination of arsenic species in urine samples after the ingestion of seaweed by four volunteers. We observed substantial increases of DMAA concentrations in the samples collected from the volunteers after the consumption of seaweed. The increase of urinary DMAA concentration is due to the metabolism of arsenosugars that are present in the seaweed. Our results suggest that the commonly used biomarkers of exposure to inorganic arsenic, based on the measurement of arsenite, arsenate, MMAA, and DMAA, are not reliable when arsenosugars are ingested from the diet.

Enhancing effects of an organic arsenic compound, dimethylarsinic acid (cacodylic acid), in a multi‐organ carcinogenesis bioassay

AbstractThe modifying effects of dimethylarsinic acid (DMA) on tumor induction in various organs were examined using a multi‐organ rat carcinogenesis bioassay. A total of 124 six‐week‐old male F344/DuCrj rats were divided randomly into seven groups. For establishment of wide‐spectrum initiation, animals in Groups 1–5 were treated with five carcinogens, namely N‐nitrosodiethylamine (DEN), N‐methyl‐N‐nitrosourea (MNU), 1,2‐dimethylhydrazine (DMH), N‐butyl‐N‐(4‐hydroxybutyl)nitrosamine (BBN) and N‐bis(2‐hydroxypropyl)nitrosamine (DHPN) in the first four weeks. After a two‐week interval, Groups 1–5 were then given 0, 50, 100, 200 and 400 ppm DMA, respectively, in drinking water. Groups 6 and 7 received 100 and 400 ppm DMA without any carcinogen pretreatment. All rats were sacrificed at the end of week 30. In the initiated groups (Groups 1–5), DMA enhanced tumor development in the urinary bladder, kidney, liver and thyroid gland. The main arsenic species in urine samples was DMA itself. In conclusion, the observed enhancement of carcinogenesis in the urinary tract as well as in the liver and thyroid gland may be directly due to this arsenic compound.