Species In Human Urine Research Articles

Synthesis of a novel magnetic nanomaterial for the development of a multielemental speciation method of lead, mercury, and vanadium via HPLC-ICP MS

A new magnetic functionalized material based on graphene oxide magnetic nanoparticles named by us, M@GO-TS, was designed and characterized in order to develop a magnetic solid-phase extraction method (MSPE) to enrich inorganic and organic species of lead, mercury, and vanadium. A flow injection (FI) system was used to preconcentrate the metallic and organometallic species simultaneously, while the ultra-trace separation and determination of the selected species were achieved by high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP MS). Therefore, preconcentration and separation/determination processes were automated and conducted separately. To the best of our knowledge, this is the first method combining an online MSPE and HPLC-ICP MS for multielemental speciation. Under the optimized conditions, the enrichment factor obtained for PbII, trimethyllead (TML), HgII, methylmercury (MetHg), and VV was 27. The calculated LOD for all studied species were as follows: 5 ng L−1, 20 ng L−1, 2 ng L−1, 10 ng L−1, and 0.4 ng L−1, respectively. The RSD values calculated with a solution containing 0.5 μg L−1 of all species were between 2.5 and 4.5%. The developed method was validated by analyzing Certified Reference Materials TMDA 64.3 for total concentration and also by recovery analysis of the species in human urine from volunteers and a seawater sample collected in Málaga. The t statistical test showed no significant differences between the certified and found values for TMDA 64.3. All the recoveries obtained from spiked human urine and seawater samples were close to 100%. All samples were analyzed using external calibration. The developed method is sensitive and promising for routine monitoring of the selected species in environmental waters and biological samples.Graphical abstract

Programmable Millifluidic Platform Integrating Automatic Electromembrane Extraction Cleanup and In-Line Electrochemical Detection: A Proof of Concept.

A fully automatic millifluidic sensing platform coupling in-line nonsupported microelectromembrane extraction (μ-EME) with electrochemical detection (ECD) is herein proposed for the first time. Exploiting the features of the second generation of flow analysis, termed sequential injection (SI), the smart integration of SI and μ-EME-ECD enables (i) the repeatable formation of microvolumes of phases for the extraction step in a membrane-less (nonsupported) arrangement, (ii) diverting the acceptor plug to the ECD sensing device, (iii) in-line pH adjustment before the detection step, and (iv) washing of the platform for efficient removal of remnants of wetting film solvent, all entirely unsupervised. The real-life applicability of the miniaturized sensing system is studied for in-line sample cleanup and ECD of diclofenac as a model analyte after μ-EME of urine as a complex biological sample. A comprehensive study of the merits and the limitations of μ-EME solvents on ECD is presented. Under the optimal experimental conditions using 14 μL of unprocessed urine as the donor, 14 μL of 1-nonanol as the organic phase, and 14 μL of 25 mM NaOH as the acceptor in a 2.4 mm ID PTFE tubing, an extraction voltage of 250 V, and an extraction time of 10 min, an absolute (mass) extraction recovery of 48% of diclofenac in urine is obtained. The proposed flow-through system is proven to efficiently remove the interfering effect of predominantly occurring organic species in human urine on ECD with RSD% less than 8.6%.

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

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

Determination of eleven small selenium species in human urine by chromatographic-coupled ICP-MS methods

BackgroundThe determination of various selenium species in urine enables a specific biomonitoring of the exposure to different selenium compounds. MethodsFor this task a coupling of three chromatographic techniques with ICP-MS was developed for the separate quantification of eleven species in urine. The first procedure was based on reverse phase chromatography and was designed for the separate determination of methyl-2-acetamido-2-deoxy-1-seleno-b-d-galactopyranoside (SeSug1), methyl-2-acetamido-2-deoxy-1-seleno-b-d-glucopyranoside (SeSug2), selenomethionine (SeMet), methylselenocysteine (MeSeC), seleno-D,L-ethionine (SeEt), methylselenic acid (MeSeA) and methylselenoglutathione (MeSeG); the second procedure was based on anion exchange chromatography and measured selenate (Se (VI)) and selenite (Se (IV)); the third procedure was based on cationic exchange chromatography and determined methyl-2-amino-2-deoxy-1-seleno-b-d-galactopyranoside (SeSug3) and the trimethylselenium ion (TMSe). A fourth method for the more sensitive determination of TMSe was upgraded by an on-line after-column reaction process. ResultsThe validation of the methods yielded sensitive detection limits of the species between 0.03 and 0.10 μg Se/L. For TMSe a detection limit of 0.02 μg Se/L resulted by the fourth method. An intra-day precision of 2.7–10.6% and a relative recovery between 87 % and 108 % confirm the robustness of the methods. ConclusionThe developed procedures enable a separate and sensitive determination of eleven selenium species in urine and thus permit the exploring of metabolic factors in the general population and particularly exposed individuals.

Dual-signal model array sensor based on GQDs/AuNPs system for sensitive protein discrimination

The accurate differentiation and identification of proteins play a vital role in many areas. Herein a novel array sensor is developed for sensitive discrimination of proteins, based on the various optical responses of GQDs/AuNPs system towards different protein species. The simultaneously generated distinct variations of fluorescence and absorbance of GQDs/AuNPs system resulted from the interactions between protein species and sensing units contribute to a dual-signal strategy for protein discrimination. The protein concentration for complete discrimination is low down to 50 nM, and accurate discriminations of protein mixture of different concentrations/molar ratio are achieved. The complementary fluorescence and absorbance response makes this dual-signal model array sensor practicable to sample of complicated matrices, demonstrated by the accurate discrimination of protein species in human urine. Moreover, six strains of microorganisms originated from three different species are also successfully discriminated with 100% accuracy (OD600 = 1.0).

IMPLEMENTATION OF AN ANALYTICAL METHOD FOR THE DETERMINATION OF INORGANIC ARSENIC SPECIES IN OCCUPATIONALLY EXPOSED HUMAN URINE SAMPLES AND ITS TOXIC EFFECTS ON EPITHELIAL CELLS OF RENAL COLLECTING TUBULE

In this study a method was implemented for the determination of total As and its inorganic species in human urine by HPLC-HG-AFS. The method was applied to workers occupationally exposed to mining and thermoelectric operations. Results shows high levels of As in urine up to 188±4 μg L-1 and As(III) up to 10.7±0.6 μg L-1. Toxic effects of As(III) at the concentration levels founded in human urine were evaluated over the morphology and fibrosis of renal epithelial collecting duct cells in vitro. Our results suggest that urinary tract epithelial renal tubular cells exposed to this concentration of As(III) result in epithelial-mesenchymal transition.

Dynamic Assessment of Functional Lipidomic Analysis in Human Urine.

The development of enabling mass spectrometry platforms for the quantification of diverse lipid species in human urine is of paramount importance for understanding metabolic homeostasis in normal and pathophysiological conditions. Urine represents a non-invasive biofluid that can capture distinct differences in an individual's physiological status. However, currently there is a lack of quantitative workflows to engage in high throughput lipidomic analysis. This study describes the development of a MS/MS(ALL) shotgun lipidomic workflow and a micro liquid chromatography-high resolutiontandem mass spectrometry (LC-MS/MS) workflow for urine structural and mediator lipid analysis, respectively. This workflow was deployed to understand biofluid sample handling and collection, extraction efficiency, and natural human variation over time. Utilization of 0.5mL of urine for structural lipidomic analysis resulted in reproducible quantification of more than 600 lipid molecular species from over 20 lipid classes. Analysis of 1mL of urine routinely quantified in excess of 55 mediator lipid metabolites comprised of octadecanoids, eicosanoids, and docosanoids generated by lipoxygenase, cyclooxygenase, and cytochrome P450 activities. In summary, the high-throughput functional lipidomics workflow described in this study demonstrates an impressive robustness and reproducibility that can be utilized for population health and precision medicine applications.

Development and validation of a simple and robust method for arsenic speciation in human urine using HPLC/ICP-MS.

In order to better distinguish the different toxic inorganic and organic forms of arsenic (As) exposure in individuals, we have developed and validated a simple and robust analytical method for determining the following six As species in human urine: arsenous (III) acid (As-III), As (V) acid, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine (AsB), and arsenocholine. In this method, human urine is diluted using a pH 5.8 buffer, separation is performed using an anion exchange column with isocratic HPLC, and detection is achieved using inductively coupled plasma-MS. The method uses a single mobile phase consisting of low concentrations of both phosphate buffer (5 mM) and ammonium nitrate salt (5 mM) at pH 9.0; this minimizes the column equilibration time and overcomes challenges with separation between AsB and As-III. In addition, As-III oxidation is prevented by degassing the sample preparation buffer at pH 5.8, degassing the mobile phase online at pH 9.0, and by the use of low temperature (-70 °C) and flip-cap airtight tubes for long term storage of samples. The method was validated using externally provided reference samples. Results were in agreement with target values at varying concentrations and successfully passed external performance test criteria. Internal QC samples were prepared and repeatedly analyzed to assess the method's long-term precision, and further analyses were completed on anonymous donor urine to assess the quality of the method's baseline separation. Results from analyses of external reference samples agreed with target values at varying concentrations, and results from precision studies yielded absolute CV values of 3-14% and recovery from 82 to 115% for the six As species. Analysis of anonymous donor urine confirmed the well-resolved baseline separation capabilities of the method for real participant samples.

Ion pairing and ion exchange chromatography coupled to ICP-MS to determine selenium species in human urine

In this work three analytical methods were developed and applied to determine a broad spectrum of selenium species in human urine. The methods are based on different liquid chromatographic separation techniques (ion pairing, anion exchange and cation exchange chromatography) coupled to an inductively coupled plasma-mass spectrometer (ICP-MS) for selenium specific detection. They were adjusted for the determination of nine species named selenate (Se(VI)), selenite (Se(IV)), trimethylselenium ion (TMSe), methylselenoglutathione (SeMeG), methyl-2-acetamido-2-deoxy-1-seleno-β-D-galactopyranoside (SeSug1), methyl-2-amino-2-deoxy-1-seleno-β-D-galactopyranoside (SeSug3), selenomethionine (SeMet), selenoethionine (SeEt), methylselenocysteine (SeMCys) and provide detection limits between 0.10 and 0.19 μg Se per L. The procedures were applied to 45 urine samples of individuals of the general population. SeSug1 was detected in 100% (median: 1.79 μg g−1 creatinine; range: 0.47–8.97 μg g−1 creatinine) and SeSug3 (0.80; 0.07–3.53 μg Se per g creatinine) in 80% of the study population. SeSug1 and SeSug3 were strongly correlated; however a shift of their relation was observed in dependence of the exposure level. In 20% of the samples compounds were detected, which could be related to Se(VI) (0.12; 0.03–1.12 μg Se per g creatinine) and SeMCys (0.13; 0.03–0.41 μg Se per g creatinine). TMSe was detected in 18% of the samples. But whenever TMSe was detected, it was found in considerable concentrations (2.91; 2.72–4.42 μg Se per g creatinine). The species SeMet, SeEt, SeMeG and Se(IV) were not detected in any of the samples. The results of the study are consistent with the literature in which SeSug1 is well-established as major selenium species in human urine since years. Moreover, the results show that the composition of urinary eliminated Se-species might change depending on the Se exposure level. Finally, the results indicate a polymorphic selenium metabolism related to the formation of TMSe.

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.

Determination of seven arsenic compounds in urine by HPLC-ICP-DRC-MS: a CDC population biomonitoring method

A robust analytical method has been developed and validated by use of high-performance liquid chromatography inductively coupled plasma mass spectrometry with Dynamic Reaction Cell (DRC) technology that separates seven arsenic (As) species in human urine: arsenobetaine (AB), arsenocholine, trimethylarsine oxide (TMAO), arsenate (As(V)), arsenite (As(III)), monomethylarsonate, and dimethylarsinate. A polymeric anion-exchange (Hamilton PRP X-100) column was used for separation of the species that were detected at m/z 75 by ICP-DRC-MS (PerkinElmer SCIEX ELAN DRCII) using 10% hydrogen-90% argon as the DRC gas. The internal standard (As) is added postcolumn via an external injector with a sample loop. All analyte peaks were baseline-separated except AB and TMAO. Analytical method limits of detection for the various species ranged from 0.4 to 1.7 microg L(-1) as elemental As. As(III) conversion to As(V) was avoided by adjusting the urine sample to <pH 6. Analyses of the National Institute of Standards and Technology standard reference material (SRM) 2670 and 2670a elevated and National Institute for Environmental Studies certified reference material (CRM) no. 18 for arsenic species yielded results within the certified SRM-CRM limits for As species; likewise, the sum of all species compared favorably to SRM 2670 and 2670a target values for total As. This As speciation method is now being used in a production mode for the analysis of a US population survey, the National Health and Nutrition Examination Survey, as well as for other biomonitoring studies of As exposure. This method meets our requirement for sample throughput of 2,000-3,000 sample analyses per year.

Fast Determination of Arsenic Species and Total Arsenic in Urine by HPLC-ICP-MS: Concentration Ranges for Unexposed German Inhabitants and Clinical Case Studies

A fast and reliable high-pressure liquid chromatography (HPLC)-inductively coupled plasma-mass spectrometry (ICP-MS) routine method was developed for the determination of inorganic arsenic [As(III) and As(V)], organic monomethylarsonate [MMA(V)], dimethylarsinate [DMA(V)], and arsenobetaine (As-B) in human urine. The complete method validation is described, including internal and external quality assurance. Limits of quantification for the As species are 0.1 microg/L, which is sufficient to determine background concentrations of the arsenic species in human urine. Additionally, total As in all urine samples was determined by conventional ICP-MS. Mean concentrations for 82 non-exposed inhabitants from northern Germany are 12.7, 5.9, 4.0, 0.23, 0.52, and 0.17 microg/L for total As, As-B, DMA(V), As(III), MMA(V), and As(V), respectively. Approximately 15% of the total As was not identified by the anion exchange HPLC-ICP-MS method, and could be other As metabolites in urine. Two case studies underline the need for As speciation, especially when total urinary arsenic concentrations are elevated. In the first case, we investigated the effect of seafood consumption on the concentration of different arsenic species in urine for different persons. A maximum enhancement of total As from 1 up to 2,200 microg/L (2,000 microg/L for As-B) was observed after a normal fish meal. The second case describes the exposure of a 7-year-old child to As(III) by inhalation of calcium arsenite powder. Five hours after exposure, the concentrations in the child's urine for As-B, DMA(V), As(III), MMA(V), and As(V) were < 0.1, 189, 304, 229, and 27 microg/L, respectively, and these concentrations were reduced to normal background values after 4 days.

Determination of arsenic species in human urine using high performance liquid chromatography (HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS)

A speciation technique for arsenic (As) has been applied using ion pair reverse phase-high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (RP-HPLC-ICP-MS). Six As-species (arsenite, arsenate, dimethylarsinic acid, dimethylarsinous acid, monomethylarsonic acid and monomethylarsonous acid) have been separated with isocratic elution within less than 6 minutes. A cation exchange column was used for separation of AsB, AsC, Tetra (Me4As+) and TMAsO. The As chemical form and oxidation state is highly important in respect to toxicity; therefore total As-determination is insufficient for a complete toxicological evaluation and risk assessment. Arsenic-speciation has been studied on urine samples of children from an As-affected area in the Iron Quadrangle, Brazil. DMAsV and MMAsV were the major urinary metabolites in these samples. The mean value for total As-concentration of all samples (n = 15) was 26.3 ng As mL−1 with a range of 16.1 to 55.2 ng As mL−1. TMAsO and AsC (arsenocholine) were not detected in this study. In most samples, monomethylarsonous acid [MMAsIII] was detected up to 2.0 ng As mL−1. DMAsIII was not detected at any time, most probably due to volatilisation and some oxidation to DMAsV. The chromatographic recoveries, calculated from ([sum(species) × 100]/total As in urine samples), ranged from 77.4 to 94.9%. This work also contributes to the pertinent discussion regarding the reliability of MMAsIII/DMAsIII speciation in urine.

Simultaneous speciation of arsenic and selenium in human urine by high-performance liquid chromatography inductively coupled plasma mass spectrometry

A procedure for the simultaneous determination of six selenium species and six arsenic species in human urine by ion-pair, reversed-phase liquid chromatography coupled to ICP-MS has been developed. Selenium species, trimethylselenonium ion (TMSe), selenocystine (SeCys), selenite (SeIV), selenourea (SeUr), selenomethionine (SeMet), selenoethionine (SeEt), and arsenic species, arsenocholine (AsC), arsenobetaine (AsB), dimethylarsinic acid (DMA), methylarsonic acid (MMA), arsenite (AsIII), arsenate (AsV) were separated on a C8 reversed phase column by a mobile phase of 13.0 mmol l−1 tetrabutylammonium hydroxide (ion-pair reagent) and 1.3% methanol at pH 5.7–5.8 (adjusted with malonic acid). The total analysis took less than 10 min with isocratic elution at a flow rate of 1.0 ml min−1, and was free from chloride interference due to the complete separation of the analyte species from chloride. The detection limits, in synthetic urine for an injection volume of 50 μL, ranged between 0.1 and 0.4 μg l−1 for the six arsenic species (except AsC) and between 0.7 and 2 μg l−1 for the six selenium species (at m/z 78). The repeatability was less than 10% (RSD) for 1 μg l−1 arsenic species and 5 μg l−1 selenium species, except for AsC. Quantification was based on response factors in a synthetic urine matrix relative that of AsV in the mobile phase. The response factors for selenium species showed considerable compound dependence. Recoveries from spiked urine samples ranged from 81% to 103%, except for SeUr and SeEt, which were not recovered. The method was applied to the determination of arsenic and selenium species in urine, which only required filtering through a 0.45 μm membrane filter and dilution with mobile phase in order to measure arsenic and selenium urinary metabolites.

Determination of total toxic arsenic species in human urine using hydride generation inductively coupled plasma mass spectrometry

In order to evaluate people’s exposure to arsenic in drinking water, hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS), a simple and fast method, was developed to determine the total concentration of toxic arsenic species in the urine samples. Different factors affecting the hydride generation reactions were studied. It was found that under optimized conditions with 1% NaBH4, 0.2 M HCl and 0.05 M L-cysteine, the toxic arsenic species were effectively separated from non-toxic species. In addition, it was discovered that inorganic and monomethylarsenic species have similar sensitivities with HG-ICP-MS detection, while dimethylarsenic species have slightly lower sensitivity. With this method, good linearity, repeatability and recovery were achieved along with the low detection limit of 6 ng L−1 (3σ). This HG-ICP-MS method was employed to analyze a NIST standard reference material, SRM2670a, as well as urine samples from subjects under an arsenic exposure and remediation study; the concentration of all toxic species determined by this method was in good agreement with that measured by IC-ICP-MS speciation. The results suggested this HG-ICP-MS method is better than an ICP-MS total arsenic measurement in evaluating people’s exposure to inorganic arsenic in drinking water, because it can exclusively measure toxic arsenic species in urine, which come from inorganic arsenic exposure, with better sensitivity.

Thermodynamic Analysis of Arsenic Methylation

The Challenger mechanism for the methylation of arsenic is a repeating sequence of a two-electron reduction of pentavalent arsenic As(V) species to trivalent arsenic As(III) species followed by a methylation-oxidation reaction forming the successive methyl As(V) species. This unusual oxidation-reduction sequence prompted an examination of the thermodynamics of these reactions. Quantum chemical methods are employed to estimate the thermodynamic parameters for the methyl arsenic species. The sequence is thermodynamically favored at neutral pH for redox potentials with pe < 0 and methyl cation activities pCH3+ < -3 to -7 depending on the precise situation analyzed. The observed distribution of methyl arsenic species in human urine, which is remarkably constant across many studied populations, can be reproduced using an equilibrium model if the formation of TMA species is prevented. The estimated thermodynamic parameters are sufficiently accurate to evaluate questions of thermodynamic plausibility but not the precise details of speciation.

Method for the determination of five toxicologically relevant arsenic species in human urine by liquid chromatography–hydride generation atomic absorption spectrometry

An analytical method for the simultaneous quantitation of arseneous acid (As(III)), arsenic acid (As(V)), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and trimethylarsine oxide (TMAO) in human urine by coupling of high-performance liquid chromatography with hydride generation atomic absorption spectrometry (HPLC/HG-AAS) via a flow-injection interface is presented. After arsenic species separation by anion-exchange displacement chromatography the compounds are on-line reduced to their corresponding hydrides and detected by atomic absorption spectrometry. Detection limits range from 1.1 (TMAO) to 2.6 μg/L (As(V)). The method has been applied to determine arsenic species in the urine of a volunteer before and after consumption of seafood as well as to analyse certified reference urine samples for their arsenic species content.

Identification of some arsenic species in human urine and blood after ingestion of Chinese seaweed Laminaria

Algae contain high amounts of arsenic in the form of arsenosugars. The metabolism and toxicology of these arsenic species are not yet fully understood. Three sets of experiments have been conducted in which the alga Laminaria was ingested by 2 to 5 healthy volunteers. Total arsenic concentrations in urine and in blood, packed blood cells and serum have been determined using ICP-MS and HGAFS, respectively. Neutron activation analysis was used for the determination of the total arsenic content in algae samples. Speciation analysis of urine and serum samples has been carried out using HPLC-ICP-MS. HPLC-ES-MS/MS has been used for structural confirmation. The stability of the arsenosugars in simulated gastric fluid was studied for both boiled and unboiled seaweed. A maximum level of arsenic in urine appears within 15 to 25 h after ingestion. Total arsenic and speciation analysis revealed no marked increase in arsenic blood, serum and packed cells levels up to 7 h after ingestion. Dimethylarsinic acid (DMA), methylarsonic acid (MA) and dimethylarsinoylethanol (DMAE) have been positively identified in urine sampled after algae intake. Another 5 species remain unknown. In simulated gastric fluid incubated with algae, the larger share of the arsenosugars degrade within a short time span into a compound with a mass of 254 Da.

Reversed-phase liquid chromatography with mixed ion-pair reagents coupled with ICP-MS for the direct speciation analysis of selenium compounds in human urine

A sensitive and robust method for the determination of five inorganic and organic Se species in human urine by reversed-phase liquid chromatography with mixed ion-pair reagents coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) is described in this paper. A good separation for anionic, cationic and neutral Se species, namely selenate [Se(VI)], selenourea (SeUr), selenomethionine (SeMet), selenoethionine (SeEt), and trimethylselenonium ion (TMSe+), was achieved within 15 min on a LiChrosorb RP 18 reversed-phase column by using mixed ion-pair reagents of 2.5 mM sodium 1-butanesulfonate and 8 mM tetramethylammonium hydroxide, with isocratic elution at a flow rate of 1.0 mL min−1. The detection limits of the five Se species obtained by HPLC-ICP-MS ranged from 0.6 to 1.5 ng Se mL−1 using an injection volume of 20 µL. It is noteworthy that the urine sample can be directly injected into the analytical system without any pre-treatment, except a filtration with a 0.45 µm membrane filter, and that the determination of Se species was free from chloride-induced matrix interference. In addition, no serious deterioration in column performance or decrease in the sensitivity of ICP-MS was observed for the experimental period of three months. In Japanese urine samples, no detectable SeMet, SeUr, and SeEt could be found, even if the total Se concentration was higher than 100 ng Se mL−1. On the contrary, TMSe+ and two unknown Se species (U1 and U2) were detected in the urine. The major unknown, U1, was found in all of the measured urine samples, suggesting that it might be one of the important Se metabolites.

HG/LT-GC/ICP-MS coupling for identification of metal(loid) species in human urine after fish consumption.

Human urine samples after fish consumption have been investigated by low-temperature gas chromatography with inductively coupled plasma mass spectrometric detection after sample derivatization by hydride generation (HG/LT-GC/ICP-MS). This analytical technique enabled the identification of organometal(loid) compounds in human urine; species of the six elements germanium, arsenic, selenium, tin, antimony, and mercury were determined. Three different organic selenium species, two germanium species, seven arsenic species, four tin species, five antimony species, and one species of mercury were found; 18 of the 22 species detected could be identified. The relative detection limits ranged between 2 and 12 pg x L(-1) (x=element). These organometal(loid) compounds probably build up in the human body under the influence of micro-organisms, in the presence of hydrogen sulfide and methane, in the human intestine.