High Performance Liquid Chromatography With Inductively Coupled Plasma Mass Spectrometry Research Articles

Vacancies-rich MOFs-derived magnetic CoFe encapsulated in N-doped carbon nanotubes as peroxymonosulfate activator for p-arsanilic acid removal

A rational design of high-performance catalysts with peroxymonosulfate (PMS) activation and arsenic adsorption capacities for the removal of p-arsanilic acid (p-ASA) is in high demand but remains a significant challenge. Herein, vacancies-rich metal–organic frameworks (MOFs) were constructed by room-temperature co-precipitation procedure, and the magnetic CoFe encapsulated in N-doped carbon nanotubes (CoFe-N-CNTs) were prepared using MOFs template by an annealing process under a nitrogen atmosphere. The synthesis conditions of CoFe-N-CNTs were optimized by tuning Fe/Co ratio and carbonization temperature. The CoFe-N-CNTs/PMS system showed favorable removal performance, achieving complete degradation of 46 μM p-ASA within 3 min and a total arsenic removal efficiency of 98% within 30 min at 0.1 g/L catalyst and 400 μM PMS. The degradation rate (kobs) and total arsenic removal efficiency towards p-ASA by CoFe-N-CNTs/PMS system were 6.7 and 2.7 times of those in the MOFs without vacancies-derived catalyst/PMS system, respectively. CoFe-N-CNTs/PMS system exhibited robust and efficient performance over a broad range of pH (4.5–9.0) and in different water matrices. Scavenging experiments and electron paramagnetic resonance (EPR) results demonstrated that non-radical singlet oxygen (1O2), sulfate radicals (SO4−), hydroxyl radicals (OH), and superoxide (O2−) were involved in p-ASA decomposition. Electron transfer and direct oxidative transfer process (DOTP) also contributed to p-ASA degradation. High-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) analysis indicated that the arsenic moiety was cleaved from p-ASA in the form of As(III) and then rapidly oxidized to As(V). X-ray photoelectron spectroscopy (XPS) analysis indicated the removal of inorganic arsenic followed the mechanism of the inner-sphere complex. This study highlights the in-situ synthesis of CoFe-N-CNTs with outstanding activities for catalytic degradation and arsenic removal of organoarsenicals.

Quantification of ultra-trace organolead species in environmental water by inductively coupled plasma mass spectrometry with online solid-phase extraction and high performance liquid chromatographic separation

Quantification of organolead compounds in environmental water is an essential task considering much higher toxicity and bioavailability of organolead species than inorganic plumbic ions. However, the speciation of ultra-trace organolead compounds at sub ng L−1 levels is challengeable for current instruments incorporating high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and even offline enrichment that offer detection limits around several to tens of ng L−1. In this paper, an online solid-phase extraction (SPE) coupled HPLC-ICP-MS method was developed for speciation analysis of trace lead in water. Graphene oxide bounded silica particles (GO@SiO2) was utilized as the SPE adsorbent because of its superior performance over graphene bounded silica particles and commercial C18 packing particles. High enrichment factors (1603 for TML and 1376 for TEL) were obtained when lead species in 10 mL sample was adsorbed by 1 mM sodium dodecyl benzene sulfonate (SDBS) preconditioned GO@SiO2 at 10 mL min−1 and then eluted by 5 μL of 5 mM SDBS. Because of the highly efficient preconcentration, detection limits were downscaled to be 0.018 for TML and 0.023 ng L−1 for TEL with relative standard deviations below 5%. Additionally, the proposed method also yielded rapid separation of Pb(II), TML and TEL (8 min) by using green mobile phases (aqueous solutions of 5 mM sodium 1-pentanesulfonate at pH 2.5 with/without 4 mM tetrabutylammounium hydroxide). Upon successful application to fresh water, TML and TEL were only presented in the river water whereas Pb(II) was only existed in the tap water, along with accuracy validation by good spiked recoveries (93–106%).

Arsenic Species Analysis at Trace Level by High Performance Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry

A sensitive and accurate simultaneous continuous analysis for six arsenic species including arsenobetaine (AsB), arsenocholine (AsC), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenite (AsIII), and arsenate (AsV) has been developed by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). An anion-exchange column of Hamilton PRP-X100 (Switzerland) was applied for separation of the six arsenic species with gradient elution of 1.25 mmol/L Na2HPO4 and 11.0 mmol/L KH2PO4 as the mobile phase A and 2.5 mmol/L Na2HPO4 and 22.0 mmol/L KH2PO4 as the mobile phase B. The linearity ranges for AsB, AsC, MMA, DMA, AsIII, and AsV were between 0.5 and 50.0 μg/L, and the detection limits of the six arsenic species were all within 0.01–0.35 ng/L. The relative standard deviations (RSDs) were within 2.26–3.68% and the recovery rates of samples ranged from 95 to 103%. The proposed method was applied for the arsenic speciation analysis of sediment pore-water samples, which were taken from the supernatant after centrifugation and filtration.

Stabilities of iodide and iodate for iodine speciation analysis in soils

The primary objective of this study was to develop a simple method that can be used to extract the more readily mobilizable iodine species from soil while at the same time minimizing the transformation between IO3− and I−, the two most commonly found iodine species in the soil. High performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used for iodine speciation analysis in soil. A sample pre-treatment process based on alkaline extraction in the presence of EDTA was optimized for the extraction of these iodine species. Good results were achieved using 10% ammonium hydroxide (v/v) and 0.5 mM EDTA where the transformation between IO3− and I− was clearly minimized. The method was applied to several soil reference materials. Recoveries of IO3− and I− spiked into these materials ranged from 85 to 115%. The most suitable sample collection and soil preparation techniques were also evaluated in this work.

Arsenic transformation behaviour during thermal decomposition of P. vittata, an arsenic hyperaccumulator

Thermal treatment of P. vittata, an arsenic hyperaccumulator harvested from contaminated land is a promising method of achieving volume reduction, energy production and arsenic (As) recovery simultaneously. In this paper, the arsenic transformation characteristics of field-harvested P. vittata were investigated during its pyrolysis and gasification process. The produced solid residue and flue gas were analysed by a high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) to determine both the arsenic concentration and speciation. Moreover, the occurrence of arsenic in the solid residues was further identified as soluble and insoluble, which can feed information to the next arsenic recovery step. Results show that the fuel arsenic into gas phase increases firstly from 400°C to 600°C, but then drops from 600°C to 800°C, probably due to the self-retention of arsenic by CaO enriched in this P. vittata. Further increasing temperature to 900°C will result in fast arsenic release. Gasification results in slightly higher arsenic release into the gas phase compared with pyrolysis.

Genetic polymorphisms of PPAR gamma, arsenic methylation capacity and breast cancer risk in Mexican women.

To evaluate whether the presence of polymorphisms of peroxisome proliferator-activated receptor gamma PPARγ (Pro 1 2Ala) and PPARGC1B (Ala203Pro) modifies the association between the inorganic arsenic (iAs) methylation capacity and breast cancer (BC). Mexican women were interviewed, and blood and urine samples were collected from them (cases/controls= 197/220). The concentration of urinary arsenic species and the polymorphisms of interest were determined by high-performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and polymerase chain reaction (PCR), respectively. In women with a high %MMA (urinary monomethyl arsenic) and high primary methylation ratio (PM = MMA/iAs), the risk of BC was increased (odds ratio [OR]%MMA T3 vs.T1= 3.60: 95% confidence interval [CI] 2.02-6.41, ORPMI T3 vs.T1= 3.47: 95%CI 1.95-6.17), which was maintained after adjusting for polymorphisms. No significant interactions were observed between the polymorphisms and the arsenic variables on the risk of BC. Pro 12Ala and Ala203Pro polymorphisms did not modify the association between the iAs methylation capacity and BC.

Speciation of Selenium in Enriched Garlic Sprouts by High-Performance Liquid Chromatography Coupled with Inductively Coupled Plasma-Mass Spectrometry

Selenium species in enriched garlic (Allium Sativum L) sprouts were determined by high-performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). The garlic was grown in a 10 mg/L selenite nutrient solution, and the total selenium accumulated by the sprouts was 250 µg/g. Three mobile phase systems were investigated and a buffer of 20 mmol/L ammonium acetate/5% methanol was chosen for subsequent analysis. Comparative experiments were performed to determine the selenium species in the garlic sprouts with four extraction solutions: 0.1 mol/L HCl, 0.1 mol/L NaOH, 20 mmol/L ammonium acetate/5% methanol and protease XIV. The most suitable results were obtained using 0.1 mol/L HCl as the extracting solution. Validation was performed; all selenium compounds had recoveries of 102.5% to total selenium, with good linearity and precision. The major compound accumulated in the garlic sprouts was methylselenocysteine, which accounted for 65.01% of the selenium.

Determination of arsenic species in rice grains using HPLC-ICP-MS

Determination of As species in rice is necessary because inorganic As species (arsenate (AsV) and arsenite (AsIII)) are more toxic than organic As (monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)). This study evaluated the As species in Korean and USA rice grains. Levels were determined using microwave extraction and high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry (HPLC-ICPMS). Arsenite and DMA were the major species detected in Korean and USA rice. The percentage of inorganic As was 76.94% (54.50–87.86%) for Korean rice and 69.28% (52.94–72.92%) for USA samples. The order and percentage of As species observed in Korean and USA rice were AsIII (70%)>DMA (24%)>AsV (5%)>MMA (1%), and AsIII (64%)>DMA (28%)>AsV(5%)>MMA (3%), respectively. The AsIII concentrations were not significantly different in Korean rice grains, compared to USA grains. The high AsIII predominance indicates an elevated toxic effect of As in rice grains and needs further attention.

Environmental exposure to arsenic may reduce human semen quality: associations derived from a Chinese cross-sectional study

BackgroundRecent observations in in vitro and in vivo models suggest that arsenic (As) is an endocrine disruptor at environmentally-relevant levels. When exposed to As, male rats and mice show steroidogenic dysfunction that can lead to infertility. However, the possible effects of As on human male semen quality remain obscure.MethodsWe monitored the profile of As species in the urine of a reproductive-age human cohort and assessed its association with semen quality. Men (n = 96) were recruited in an infertility clinic from July 2009 to August 2010 in the Affiliated Hospital of Chongqing Institute for Population and Family Planning. Five urinary As species were analyzed by high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Clinical information on the semen volume, sperm concentration and motility was employed to catalogue and evaluate semen quality according to WHO guidelines. As species concentrations in addition to other continuous variables were dichotomized by the medians and modelled as categorical variables in order to explore using the binary logistic regression possible associations between As exposure and semen quality.ResultsUrinary concentrations (geometric mean ± SD, μg g-1 creatinine) of different As species were 7.49 (±24.8) for AsB, 20.9 (±13.7) for DMA, 2.77 (±3.33) for MMA, and 4.03 (±3.67) for Asi (AsiIII and AsiV). DMA concentrations above the median were significantly associated with below-reference sperm concentrations (P =0.02) after adjusting for age, body mass index (BMI), abstinence, smoking and drinking habits. In addition, smoking was positively associated with MMA.ConclusionReduced parameters in human semen quality are positively associated with As exposure in a reproductive-age Chinese cohort.

Arsenic Speciation in Blue Mussels (Mytilus edulis) Along a Highly Contaminated Arsenic Gradient

Arsenic is naturally present in marine ecosystems, and these can become contaminated from mining activities, which may be of toxicological concern to organisms that bioaccumulate the metalloid into their tissues. The toxic properties of arsenic are dependent on the chemical form in which it is found (e.g., toxic inorganic arsenicals vs nontoxic arsenobetaine), and two analytical techniques, high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and X-ray absorption spectroscopy (XAS), were used in the present study to examine the arsenic species distribution in blue mussels (Mytilus edulis) obtained from an area where there is a strong arsenic concentration gradient as a consequence of mining impacted sediments. A strong positive correlation was observed between the concentration of inorganic arsenic species (arsenic compounds with no As-C bonds) and total arsenic concentrations present in M. edulis tissues (R(2) = 0.983), which could result in significant toxicological consequences to the mussels and higher trophic consumers. However, concentrations of organoarsenicals, dominated by arsenobetaine, remained relatively constant regardless of the increasing As concentration in M. edulis tissue (R(2) = 0.307). XANES bulk analysis and XAS two-dimensional mapping of wet M. edulis tissue revealed the presence of predominantly arsenic-sulfur compounds. The XAS mapping revealed that the As(III)-S and/or As(III) compounds were concentrated in the digestive gland. However, arsenobetaine was found in small and similar concentrations in the digestive gland as well as the surrounding tissue suggesting arsenobetaine may being used in all of the mussel's cells in a physiological function such as an intracellular osmolyte.

Characteristics of Arsenic Metabolites in Human Liver Hepatocytes

Hyphenated technique of high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry(HPLC-ICP-MS) was applied to the determination of arsenic metabolites in Chang liver cells after arsenic incubation.Two unknown arsenicals were found,one of which was speculated as methylarsonous acid(MMAⅢ),and further characterized using standard addition method using synthesized MMA Ⅲ standard.Quantitative analysis results showed that monomethylarsenicals,dimethylarsenicals and inorganic arsenicals in hepatocytes after arsenic incubation were increasing with the increase of initial incubated arsenic concentration while the methylation rate decreasing with the increase of initial incubated arsenic concentration,which indicated that high concentration of arsenic has the inhibition to the ability of arsenic methylation of Chang liver cells.

Characteristics of Arsenic Metabolites in Human Liver Hepatocytes

采用工艺简单的水相合成法制备ZnS∶Mn量子点,并在量子点表面进行硅烷化处理,包覆一层分子印迹聚合物。将量子点与壳聚糖混合,在石英玻片上沉积,制备杂化膜,并用于4-硝基苯酚的快速测定,线性范围为1.0～8.0!mol/L;检出限为41nmol/L。此膜表现出较好的灵敏度和良好的选择性。此杂化膜具有良好的稳定性、重复使用性和可逆再生性,在无水乙醇中浸泡即可实现再生。本方法用于环境样品中4-对硝基苯酚的测定,回收率为95.5%～103.0%。

Determination of selenium species in food by high performance liquid chromatography with inductively coupled plasma mass spectrometry

An analytical method for selenium species of selenate (SeVI), selenite (SeIV), selenomethionine (SeMet), selenocystine (SeCys2 ) and selenoethionine (SeEt) was established using high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A Hamilton PRP X-100 reversed-phase anion exchange column (250 mm x 4.6 mm, 5 microm) with a 5 mmol/L citric acid buffer solution (pH 4.5, adjusted with 20% (v/ v) ammonia) as mobile phase was used for separation, and ICP-MS was used for detection. The five species were completely separated within 21 min. All the linear correlation coefficients of the five selenium species were greater than 0.999 5, and the detection limits of SeVI, SeIV, SeMet, SeCys2, SeEt were 0.4, 0.4, 5.6, 0.9 and 1.2 microg/L, respectively. The extraction procedure was studied for fresh mushroom and pork samples. For water-soluble selenium compounds, citric acid was a good extraction solution, and the recoveries were around 100% for inorganic selenium and in the range of 85.0% - 95.3% for SeMet; but worse for SeCys2 and SeEt. As for the proteinase K, the recoveries of SeCys2 and SeEt were raised to the range of 79.9% -91.5%. The method has the advantages of simple operation and good accuracy, and can be used for the quantitative determination of the five selenium species in food.

Speciation Analysis of Organotin Compounds in Sediment by Hyphenated Technique of High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry

A hyphenated technique of high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was applied to the simultaneous determination of five organotin compounds in the sediment samples. Agilent TC-C18 column was selected; mobile phase of the HPLC was CH3CN:H2O-CH3COOH(65:23:12, V/V), 0.05% TEA, pH 3.0 at flow rate 0.6 mL min−1, and 30% O2/Ar mixed gas was added to the make-up gas, which not only reduced the carbon buildup on the cones but also protected the cones. To reduce solvent loading on the plasma, the double-pass spray-chamber was peltier cooled to −5 °C. The high RF power (1500 W) helped the samples to decompose completely. A mixed standard solution of five mixed organotin compounds from 100 μg L−1 to 1 μg L−1 was used for the method assessment. The results indicate that the correlation coefficient of calibration curves (R2) for each organotin compound was over 0.998. The international standard reference PACS-2 samples were treated by supersonic extraction with mobile phase added 0.2% tropolone. Two organotin compounds including dibutyltin (DBT) and tributyltin (TBT) were detected with this method. The values of dibutyltin (DBT) and tributyltin (TBT) were 0.99 mg kg−1 and 0.83 mg kg−1, respectively. The results showed good accordance with the certified values. The recoveries from the standard addition for five organotins were over 80%.

Speciation Analysis of Organotin Compounds in Shellfish by Hyphenated Technique of High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry

The hyphenated technique of high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was applied to the simultaneous determination of five organotin compounds in the shellfish samples. The Agilent TC-C 18 column was used for the separation, the mobile phase of the HPLC was CH 3CN:H 2O:CH 3COOH = 65:23:12 (v/v/v), 0.05% TEA, pH 3.0, at a flow rate of 0.4 ml min −1. A mix standard solution of five mixed organotin compounds from 100 µg l −1 to 0.5 µg l −1 was used for the method assessment. The experimental results indicate that the correlation coefficient of calibration curves ( R 2) for each organotin compound was over 0.998. The shellfish samples were treated by supersonic extraction with the same mobile phase for 30 min. The four organotin compounds including dibutyltin (DBT), tributyltin (TBT), diphenyltin (DPHT), and triphenyltin (TPHT) in the shellfish samples were detected by this method. It was found that the domain compounds in the samples were TBT and TPHT. The recovery tests from the standard addition for TMT, TBT, and TPHT were over 80%. However, the recoveries of DPHT and DBT were relatively low, 37.3% and 75.2%, respectively. The reason might be attributed to the decomposition of those compounds during the extraction procedure.

Arsenic Speciation of Arsine-Exposed Blood Samples by High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry and As-Adduct, A Possible Indicator of AsH3 Exposure

Arsine (AsH(3))-exposed human blood samples were analyzed by high-performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for arsenic speciation. After exposure of human blood samples to AsH(3) vapor for 90 min at room temperature, partial hemolysis was observed. Plasma samples from these whole blood samples were prepared by centrifugation at 1600 x g for 10 min and analyzed by HPLC-ICP-MS. In addition to arsenite [As(III); degraded from AsH(3)], an unidentified arsenic species (As-adduct) was detected at a retention time of 1.1 min. Following ultrafiltration of the plasma samples using a molecular weight cut-off of 10 kDa, As-adduct was not detected in the filtrate. To clarify the origin of As-adduct, AsH(3) was added to blank plasma and As(III) was added to both whole blood and hemolyzed blood. Although As(III) was detected in all samples, As-adduct was not detected. These results indicate that As-adduct was derived from erythrocytes during the process of hemolysis by AsH(3) and further suggest that As(III) and plasma ingredients do not contribute to As-adduct production. Therefore, the presence of As-adduct in blood could represent an indicator of acute arsine poisoning.

HPLC‐ICP‐MS Speciation Analysis of Arsenic in Urine of Japanese Subjects without Occupational Exposure

The toxicity and carcinogenicity of arsenic depend on its species. Individuals living in Japan consume much seafood that contains high levels of organoarsenics. Speciation analysis of urinary arsenic is required to clarify the health risks of arsenic intake. There has been no report of urinary arsenic analysis in Japan using high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). We performed speciation analysis of urinary arsenic for 210 Japanese male subjects without occupational exposure using HPLC-ICP-MS. The median values of urinary arsenics were as follows: sodium arsenite (AsIII), 3.5; sodium arsenate (AsV), 0.1; monomethylarsonic acid (MMA), 3.1; dimethylarsinic acid (DMA), 42.6; arsenobetaine (AsBe), 61.3; arsenocholine, trimethylarsine oxide, and unidentified arsenics (others), 5.2; and total arsenic (total As), 141.3 microgAs/l. The median creatinine-adjusted values were as follows: AsIII, 3.0; AsV, 0.1; MMA, 2.6; DMA, 35.9; AsBe, 52.1; others 3.5; and total As, 114.9 microgAs/g creatinine. Our findings indicate that DMA and AsBe levels in Japan are much higher than those found in Italian and American studies. It appears that the high levels of DMA and AsBe observed in Japan may be due in part to seafood intake. ACGIH and DFG set the BEI and BAT values for occupational arsenic exposure as 35 microgAs/l and 50 microgAs/l, respectively, using the sum of inorganic arsenic (iAs), MMA, and DMA. In the general Japanese population, the sums of these were above 50 microgAs/l in 115 (55%) samples. We therefore recommend excluding DMA concentration in monitoring of iAs exposure.

Mass spectrometry study of hemoglobin‐oxaliplatin complexes in colorectal cancer patients and potential association with chemotherapeutic responses

Oxaliplatin is the most active platinum (Pt)-containing anticancer drug for the treatment of advanced colorectal cancer. We report here the study of potential association of the levels of oxaliplatin-protein complexes in 19 cancer patients with treatment efficacy using size-exclusion high-performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC/ICPMS) and nanoelectrospray ionization mass spectrometry (nanoESI-MS) techniques. Blood samples from 19 colorectal cancer patients were collected at 1 and 48 h after the first infusion of oxaliplatin. HPLC/ICPMS quantification of the oxaliplatin-protein complexes showed that the levels of Pt-protein complexes in plasma samples at 48 h were reduced by approximately 50% compared to those at 1 h, whereas those in hemolysates did not change significantly. The concentrations of hemoglobin (Hb)-oxaliplatin complexes determined by HPLC/ICPMS ranged from 3.1 to 8.7 microM. NanoESI-MS analysis of the patient hemolysates showed three distinct mass spectral profiles of the Hb-oxaliplatin complexes: (1) 1:1, (2) 1:1 with 1:2, and (3) multiple complexes of 1:1, 1:2, 1:3, and 1:4, corresponding to the Hb-oxaliplatin complex concentrations determined by HPLC/ICPMS. Potential association of variables including Hb-oxaliplatin complex concentrations with time to progress as the treatment efficacy indicator was analyzed using the Cox model. Multivariate analysis of the potential predictors showed that the statistically significant variables were Hb-oxaliplatin complex concentration (p = 0.02), performance status (p = 0.02), baseline neutrophil count (p = 0.05), and the site of the primary cancer (colon vs. rectal, p = 0.01). The hazard ratio for the concentration of the Hb-oxaliplatin complexes was 2.4, suggesting that the risk of cancer progression significantly increased with increasing of Hb-oxaliplatin complexes in patients. These results demonstrate that the level of the Hb-oxaliplatin complexes in erythrocytes is a potential biomarker for indicating inter-patient variations in oxaliplatin treatment efficacy.

High yield synthesis and characterization of isotopically enriched monoethylmercury chloride (C2H5201HgCl)

AbstractAn important but commercially unavailable compound isotopically enriched monoethylmercury chloride (C2H5201HgCl), has been synthesized from commercially available 201HgO (98.11% enriched isotopic purity) and tetraethyltin. The required synthesis time is 1 h at 90 °C, and the product is the single product of monoethylmercury chloride, yielding more than 95% as 201Hg in C2H5201Hg+ (98.19 ± 0.22% enriched isotopic purity). The synthesized product was analyzed with high‐performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC‐ICP‐MS) to determine its concentration, isotopic composition and purity. The synthetic isotopically enriched monoethylmercury synthesized can be used in speciated isotope dilution mass spectrometry (SIDMS) and isotope dilution mass spectrometry (IDMS) analyses as a standard. Copyright © 2005 John Wiley & Sons, Ltd.

Composition of Chemical Species of Selenium Contained in Selenium-Enriched Shiitake Mushroom and Vegetables Determined by High Performance Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry

Selenium (Se) species in Se-enriched shiitake mushroom (Lentinula edodes) were identified and quantified by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICPMS). Two types of Se-enriched shiitake obtained from selenite- or selenate-fertilized mushroom beds were used. More than 80% of Se in both shiitake samples could not be extracted with 0.2 M HCl. Protease digestion released a large amount of selenomethionine from the shiitake enriched with selenite. However, most of the Se in the shiitake enriched with selenate was not released by protease but was released by a cell wall digestive enzyme and most of the Se released was identified as selenate. These results indicate that the main Se species in the shiitake enriched with selenite or selenate is selenomethionine bound to protein or selenate bound to polysaccharides in the cell wall, respectively. Several Se-enriched vegetables grown on a soil fertilized with selenate were also analyzed by HPLC-ICPMS. Four Se species, selenate, Se-methylselenocysteine, selenomethionine, gamma-glutamyl-Se-methylselenocysteine, and an unknown Se compound were detected in the vegetables. The composition of Se species varied with the kinds or parts of vegetables. The main Se species in bulbs, leaves or flowers of the Se-enriched garlic, onions, cabbage and ashitaba were selenate, Se-methylselenocysteine or gamma-glutamyl-Se-methylselenocysteine, while those in fruit bodies of the peppers and pumpkin were selenomethionine bound to protein. Bioavailabilities of Se in the shiitake mushroom enriched with selenite and the vegetables enriched with selenate are expected to be high, but that in shiitake enriched with selenate may be low.