Coupled Plasma Dynamic Reaction Cell Research Articles

Blood mercury levels and fish consumption in pregnancy: Risks and benefits for birth outcomes in a prospective observational birth cohort.

BackgroundTo avoid exposure to mercury, government advice on fish consumption during pregnancy includes information on fish species to avoid and to limit, while encouraging consumption of least two portions of fish per week. Some women may, however, chose to avoid fish completely during pregnancy despite potential benefits to the fetus.ObjectivesOur aims were to evaluate the effects of blood mercury levels in pregnant women on birth outcomes in the UK, and to compare outcomes in those who ate fish with those who did not.MethodsPregnant women were enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). Whole blood samples for singleton pregnancies with a live birth were analysed for Hg by inductively coupled plasma dynamic reaction cell mass spectrometry (n = 4044). Fish intake was determined by a food frequency questionnaire during pregnancy. Data collected on the infants included anthropometric variables and gestational age at delivery. Regression models were adjusted for covariates using SPSS v23.ResultsThere were no significant associations of maternal blood Hg level with birthweight, head circumference or crown–heel length in adjusted linear regression models. Similarly, there were no increased odds of low birthweight or preterm delivery in adjusted logistic regression models. When the models were repeated after stratification into fish-eaters and there were no associations except for a negative association with birthweight in non-fish-eaters (unstandardised B coefficient −58.4 (95% confidence interval −113.8, −3.0) g, p = 0.039).ConclusionModerate mercury levels in pregnancy were not associated with anthropometric variables, or on the odds of low birthweight or preterm birth. Fish consumption may have a protective effect on birthweight. Consumption of fish in line with government guidelines during pregnancy should be encouraged.

Accurate quantification of total chromium and its speciation form Cr(VI) in water by ICP-DRC-IDMS and HPLC/ICP-DRC-IDMS

Two analytical procedures have been developed for the determination of total chromium (TCr) and its highly toxic species, i.e. Cr(VI) in water samples using the following methods: inductively coupled plasma dynamic reaction cell isotope dilution mass spectrometry (ICP-DRC-IDMS) and high performance liquid chromatography inductively coupled plasma dynamic reaction cell isotope dilution mass spectrometry (HPLC/ICP-DRC-IDMS). Spectral interferences, predominantly occurring in chromium determination, were removed using a dynamic reaction cell (DRC). The presented procedures facilitate the quantification of trace amounts – below 1µgL−1 of TCr and individual Cr species – in various water matrices including drinking water and still bottled water with different mineral composition. Special attention has been paid to the adequate preparation of isotopically enriched 53Cr(VI) standard solution in order to avoid artifacts in chromium speciation. Both procedures were fully validated as well as establishing the traceability and estimation of the uncertainty of measurement were carried out. Application of all of the above mentioned elements and of the isotope dilution technique, which provides the highest quality of metrological traceability, allowed to obtain reliable and high quality results of chromium determination in water samples. Additionally, the comparison of two methods: HPLC/ICP-DRC-MS and HPLC/ICP-DRC-IDMS for Cr(VI) determination, was submitted basing on the validation parameters. As a result, the lower values for these parameters were obtained using the second method.

Dental associations with blood mercury in pregnant women.

ObjectivesThere is curiosity concerning the source of mercury that is absorbed into the mother's blood and which may affect the developing fetus. This study therefore sets out to determine the extent to which dental amalgam (DA) may contribute to total blood mercury (TBHg) levels of pregnant women in the UK.MethodsWhole blood samples and information on diet and socio‐demographic factors were collected from pregnant women (n = 4484) enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). The whole blood samples were assayed for total mercury levels using inductively coupled plasma dynamic reaction cell mass spectrometry (ICP‐DRC‐MS), and the women were retrospectively asked about features of their dental care during the pregnancy. Linear regression was used to estimate the relative contributions of DA to TBHg levels (log‐transformed) based on R 2 values, compared to the results from dietary and socio‐demographic variables.ResultsThe contribution to the variance of the mothers' TBHg levels by dental variables was 6.47%, a figure comparable to the 8.75% shown for seafood consumption in this population. Dietary and dental variables explained 20.16% of the variance, with socio‐demographic variables contributing only a further 3.40%. The number of amalgams in the mouth at the start of pregnancy accounted for most of the variance in dental variables.ConclusionsDental amalgam contributes a comparable amount of variance in TBHg to seafood consumption in this population. However, because the measures of DA exposure were imprecise, these findings are likely to be an underestimate. There is no evidence to date in the literature that fetal exposures to mercury from maternal DAs have adverse effects on the developing child, but long‐term studies are warranted.

Selenium speciation in paired serum and cerebrospinal fluid samples of sheep

This study was performed to characterise selenium (Se) and Se species in cerebrospinal fluid (CSF) of sheep and its relation to the respective Se concentrations in serum. Paired samples from 10 adult sheep were used for the study. Five sheep were fed a diet with a marginal Se concentration of <0.05mg Se/kg diet dry weight (dw, Se–), and five animals were fed the same diet supplemented with sodium selenite revealing a concentration of 0.2mg Se/kg diet dw (Se+). The feeding strategy was conducted for two years; The results on metabolic effects were published previously. At the end of the feeding period, paired samples of serum and CSF were collected and analysed using ion exchange chromatography inductively coupled plasma–dynamic reaction cell–mass spectrometry (IEC-ICP-DRC-MS) technique for total Se concentration and concentrations of Se species. Albumin concentrations were analysed additionally.The feeding strategy caused significant differences (p<0.01) in serum Se concentrations with 33.1±5.11μg Se/l in the Se– group and 96.5±18.3μg Se/l in the Se+ group, respectively. The corresponding total Se concentrations in CSF were 4.38±1.02μg Se/l and 6.13±1.64μg Se/l in the Se– and the Se+ group, respectively, missing statistical significance (p=0.077). IEC-ICP-DRC-MS technique was able to differentiate the Se species selenoprotein P-bound Se (SePP), selenomethionine, glutathione peroxidase-bound Se (Se-GPx), selenocystine, thioredoxin reductase-bound Se, ovine serum albumin-bound Se (Se-OSA), SeIV and SeVI in ovine serum and CSF. Quantitatively, SePP is the main selenoprotein in ovine serum followed by Se-GPx. The CSF/blood ratio of albumin (QAlbumin) reflected a physiological function of the blood-CSF barrier in all sheep. QSe-species were higher than QAlbumin both feeding groups, supporting the hypothesis of local production of Se species in the brain. Significant positive regression lines for CSF vs. serum were found for albumin and Se-OSA only, suggesting a role of albumin to convey Se across the blood-CSF barrier. The ovine model, together with the IEC-ICP-DRC-MS technique to characterise the Se species, might be a worthwhile model for further studies as repeated sample collection as well as modification of the nutritional status is feasible and effective.

Selenium speciation in human serum and its implications for epidemiologic research: a cross-sectional study

Observational studies addressing the relation between selenium and human health, particularly cancer risk, yielded inconsistent results, while most recent randomized trials showed a fairly consistent pattern suggesting null or adverse effects of the metalloid. One of the most plausible explanations for such inconsistencies is inadequate exposure assessment in observational studies, commonly carried out by measuring total Se content without taking into account the specific exposure to the individual chemical forms of the metalloid, whose toxic and nutritional properties may vary greatly. Data on the distribution of these species in human blood and their correlation with overall selenium levels are very limited.The concentrations of organic and inorganic selenium species were analyzed in serum of fifty subjects sampled from the general population of the municipality of Modena, northern Italy, aged from 35 to 70 years. Samples were collected during a 30-month period, and determinations of selenium species were carried out using high pressure liquid chromatography coupled with inductively coupled plasma dynamic reaction cell mass spectrometry.The majority of selenium was found to be present as organic species, but the inorganic forms showed higher levels than expected. These species showed limited correlations with age, sex and body mass index, while the organic forms increased in subjects consuming selenium-containing dietary supplements and decreased in smokers. The length of the sample storage period strongly influenced the distribution of selenium compounds, with a clear tendency towards higher inorganic and lower organic selenium levels over time. In multivariate analysis adjusting for potential confounders, total serum selenium correlated with human serum albumin-bound selenium and, in males, with two organic species of the metalloid (selenocysteine and glutathione peroxidase-bound selenium), while little association existed with the other organic forms and the inorganic ones.These findings highlight the potential for exposure misclassification of observational epidemiologic investigations based on overall selenium content in blood and possibly other tissues, and the critical role of the storage conditions for speciation analysis.

Classification of the geographic origin of cigarettes according to Pb isotope ratios by inductively coupled plasma dynamic reaction cell mass spectrometry

ICP-DRC-MS was developed for the determination of Pb isotope ratios to distinguish between the geographic origins of cigarettes.

Adverse effects of maternal lead levels on birth outcomes in the ALSPAC study: a prospective birth cohort study.

ObjectiveTo study the associations of prenatal blood lead levels (B-Pb) with pregnancy outcomes in a large cohort of mother–child pairs in the UK.DesignProspective birth cohort study.SettingAvon area of Bristol, UK.PopulationPregnant women enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC).MethodsWhole blood samples were collected and analysed by inductively coupled plasma dynamic reaction cell mass spectrometry (n = 4285). Data collected on the infants included anthropometric variables and gestational age at delivery. Linear regression models for continuous outcomes and logistic regression models for categorical outcomes were adjusted for covariates including maternal height, smoking, parity, sex of the baby and gestational age.Main outcome measuresBirthweight, head circumference and crown–heel length, preterm delivery and low birthweight.ResultsThe mean blood lead level (B-Pb) was 3.67 ± 1.47 μg/dl. B-Pb ≥ 5 μg/dl significantly increased the risk of preterm delivery (adjusted odds ratio [OR] 2.00 95% confidence interval [95% CI] 1.35–3.00) but not of having a low birthweight baby (adjusted OR 1.37, 95% CI 0.86–2.18) in multivariable binary logistic models. Increasing B-Pb was significantly associated with reductions in birth weight (β −13.23, 95% CI −23.75 to −2.70), head circumference (β −0.04, 95% CI −0.07 to −0.06) and crown–heel length (β −0.05, 95% CI −0.10 to −0.00) in multivariable linear regression models.ConclusionsThere was evidence for adverse effects of maternal B-Pb on the incidence of preterm delivery, birthweight, head circumference and crown–heel length, but not on the incidence of low birthweight, in this group of women.

Speciation analysis of sugar phosphates via anion exchange chromatography combined with inductively coupled plasma dynamic reaction cell mass spectrometry – optimization for the analysis of yeast cell extracts

Anion exchange chromatography combined with inductively coupled plasma mass spectrometry was introduced and optimized for the separation and accurate quantification of sugar phosphates in cell extracts. Sugar phosphates have been separated on an anion exchange quaternary ammonium functionalized stationary phase (Dionex CarboPAC PA1) via gradient elution with 160 mM Na2CO3 and 50 mM NaOH. After separation, the sugar phosphates were on-line transferred to an inductively coupled plasma mass spectrometer after having passed an anion self-regenerating suppressor. Detection was performed via phosphorus as PO+ (m/z 47) was generated by the dynamic reaction cell technique using oxygen as a reaction gas. The ionization suppression process in the inductively coupled plasma caused by the high buffer strength of the chromatographic gradient was assessed by post-column flow injection analysis. It could be shown that the anion self-regenerating suppressor led to a significant reduction of signal suppression. With the new methodology excellent relative standard deviations of retention times of sugar phosphates for short- and long-term measurements were achieved. The relative standard deviations of short-term and long-term repeatability of peak areas were below 3.0 and 10.0% respectively. The absolute on-column LODs and LOQs of the optimized method were in the sub-picomole range. The developed method was applied for the purity assessment of commercially available sugar phosphate standards and evaluated for the quantification of sugar phosphates in yeast samples (Pichia pastoris) after extraction with boiling ethanol. Due to the lack of reference materials, the method accuracy was validated by method inter-comparison with an LCxLC-ESI-MS/MS based method, which has been developed in our laboratory.

Sex-specific differences in birth outcomes in relation to maternal blood lead levels: ALSPAC prospective cohort study

BackgroundThe results of previous studies of the associations between prenatal blood lead levels (BLL) and pregnancy outcomes such as birthweight and preterm delivery have been inconsistent. Such effects are important because poor birth outcomes are associated with poor developmental trajectories in infancy and have long-term implications for adult health. Male fetuses are thought to be more prone to the effects of environmental stressors on adverse pregnancy outcomes than are female fetuses, but there has been no attempt to ascertain whether there is a difference in the susceptibility to the adverse effects of maternal BLL. Our aim was to study these associations by sex in a large cohort of mother–child pairs. MethodsPregnant women resident in the Avon area of the UK were enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC), a prospective cohort study, with an expected delivery date between April, 1991, and December, 1992. Whole blood samples were collected at a median of 11 weeks' gestation (IQR 9–13) and analysed by inductively coupled plasma dynamic reaction cell mass spectrometry (n=4285, resulting in n=4267 livebirths). Self-completion postal questionnaires were used to collect data for lifestyle, diet, and environmental factors during pregnancy. Data collected for the infants included anthropometric variables and gestational age at delivery. Statistical analysis was done with SPSS (version 18). Regression models stratified by sex of the infant were adjusted for maternal height and pre-pregnancy weight, smoking, gestational age, and parity (n=1345–1525 for girls and n=1392–1626 for boys). For logistic regression, maternal BLL was categorised as less than 5 or at least 5 μg/dL. FindingsMean maternal BLL was 3·67 μg/dL (SD 1·47; median 3·41, range 0·41–19·14). The risk of low birthweight was 5·4% for girls and 4·6% for boys (p=0·234). The risk of preterm delivery was 4·9% for girls and 6·5% for boys (p=0·024). In boys, the risk of low birthweight was significantly increased for maternal BLL at least 5 μg/dL (odds ratio [OR] 2·17, 95% CI 1·22–3·86; p=0·008) in adjusted logistic regression models, but this association was not apparent in girls (1·54, 0·81–2·90; p=0·186). There was an increased risk of preterm delivery in both boys (OR 1·86, 95% CI 1·11–3·12; p=0·018) and girls (2·14, 1·10–2·94; p=0·015). Associations of maternal BLL with reductions in birthweight, head circumference, and crown–heel length in adjusted linear regression models showed weak evidence of significance in boys (p=0·030, p=0·067, and p=0·056, respectively), but were not significant in girls (p=0·196, p=0·133, and p=0·225, respectively). InterpretationEven though the mean maternal BLL was below the level generally judged to be of any consequence, there was evidence of an adverse effect of maternal BLL on pregnancy outcomes for boys, with reductions in birthweight, head circumference, and crown–heel length, and an increased risk of preterm delivery and low birthweight, in adjusted regression models. These associations were not apparent for girls, except for the risk of preterm delivery. These adverse effects could have important long-term effects on the physical and neurological development of boys. The reasons for boys being more susceptible to the effect of maternal BLL in utero are unclear but might be related to the increased demand for oxygen and nutrients to fuel a faster rate of growth, differences in the hormonal milieu, the anti-oestrogenic effect of lead, sex-specific methylation differences, or a combination thereof. There is a need to develop public health policies to minimise exposure to lead before and during pregnancy, especially for the mothers of boys, and to provide postnatal support for boys. FundingThe UK MRC and the Wellcome Trust (grant ref 092731) and the University of Bristol provide core support for ALSPAC. CMT was supported by a Daphne Jackson Trust Fellowship sponsored by the University of Bristol.

Environmental Factors Predicting Blood Lead Levels in Pregnant Women in the UK: The ALSPAC Study

BackgroundLead is a widespread environmental toxin. The behaviour and academic performance of children can be adversely affected even at low blood lead levels (BLL) of 5–10 µg/dl. An important contribution to the infant's lead load is provided by maternal transfer during pregnancy.ObjectivesOur aim was to determine BLL in a large cohort of pregnant women in the UK and to identify the factors that contribute to BLL in pregnant women.MethodsPregnant women resident in the Avon area of the UK were enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) in 1991–1992. Whole blood samples were collected at median gestational age of 11 weeks and analysed by inductively coupled plasma dynamic reaction cell mass spectrometry (n = 4285). Self-completion postal questionnaires were used to collect data during pregnancy on lifestyle, diet and other environmental exposures. Statistical analysis was carried out with SPSS v19.ResultsThe mean±SD BLL was 3.67±1.47 (median 3.41, range 0.41–19.14) µg/dl. Higher educational qualification was found to be one of the strongest independent predictor of BLL in an adjusted backwards stepwise logistic regression to predict maternal BLL <5 or ≥5 µg/dl (odds ratio 1.26, 95% confidence interval 1.12–1.42; p<0.001). Other predictive factors included cigarette smoking, alcohol and coffee drinking, and heating the home with a coal fire, with some evidence for iron and calcium intake having protective effects.ConclusionThe mean BLL in this group of pregnant women is higher than has been found in similar populations in developed countries. The finding that high education attainment was independently associated with higher BLL was unexpected and currently unexplained. Reduction in maternal lead levels can best be undertaken by reducing intake of the social drugs cigarettes, alcohol and caffeine, although further investigation of the effect of calcium on lead levels is needed.

Dietary Predictors of Maternal Prenatal Blood Mercury Levels in the ALSPAC Birth Cohort Study

Background: Very high levels of prenatal maternal mercury have adverse effects on the developing fetal brain. It has been suggested that all possible sources of mercury should be avoided. However, although seafood is a known source of mercury, little is known about other dietary components that contribute to the overall levels of blood mercury.Objective: Our goal was to quantify the contribution of components of maternal diet to prenatal blood mercury level.Methods: Whole blood samples and information on diet and sociodemographic factors were collected from pregnant women (n = 4,484) enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). The blood samples were assayed for total mercury using inductively coupled plasma dynamic reaction cell mass spectrometry. Linear regression was used to estimate the relative contributions of 103 dietary variables and 6 sociodemographic characteristics to whole blood total mercury levels (TBM; untransformed and log-transformed) based on R2 values.Results: We estimated that maternal diet accounted for 19.8% of the total variation in ln-TBM, with 44% of diet-associated variability (8.75% of the total variation) associated with seafood consumption (white fish, oily fish, and shellfish). Other dietary components positively associated with TBM included wine and herbal teas, and components with significant negative associations included white bread, meat pies or pasties, and french fries.Conclusions: Although seafood is a source of dietary mercury, seafood appeared to explain a relatively small proportion of the variation in TBM in our UK study population. Our findings require confirmation, but suggest that limiting seafood intake during pregnancy may have a limited impact on prenatal blood mercury levels.Citation: Golding J, Steer CD, Hibbeln JR, Emmett PM, Lowery T, Jones R. 2013. Dietary predictors of maternal prenatal blood mercury levels in the ALSPAC birth cohort study. Environ Health Perspect 121:1214–1218; http://dx.doi.org/10.1289/ehp.1206115

Determination of Fe and Ca in Alumina-based Nickel-Molybdenum Hydrodesulphurization Catalysts Using Inductively Coupled Plasma Optical Emission Spectrometry and Inductively Coupled Plasma Dynamic Reaction Cell Mass Spectrometry

Determination of Fe and Ca in Alumina-based Nickel-Molybdenum Hydrodesulphurization Catalysts Using Inductively Coupled Plasma Optical Emission Spectrometry and Inductively Coupled Plasma Dynamic Reaction Cell Mass Spectrometry

Seafood intake and urine concentrations of total arsenic, dimethylarsinate and arsenobetaine in the US population

Background Seafood is the main source of organic arsenic exposure (arsenobetaine, arsenosugars and arsenolipids) in the population. Arsenosugars and arsenolipids are metabolized to several species including dimethylarsinate (DMA). Objective Evaluate the association of seafood intake with spot urine arsenic concentrations in the 2003–2006 National Health Nutrition and Examination Survey (NHANES). Methods We studied 4276 participants ≥6 years. Total arsenic was measured using inductively coupled plasma dynamic reaction cell mass spectrometry (ICPMS). Urine DMA and arsenobetaine were measured by high-performance liquid chromatography coupled with ICPMS. Results Participants reporting seafood in the past 24-h had higher urine concentrations of total arsenic (median 24.5 vs. 7.3 μg/L), DMA (6.0 vs. 3.5 μg/L), arsenobetaine (10.2 vs. 0.9 μg/L) and total arsenic minus arsenobetaine (11.0 vs. 5.5 μg/L). Participants reporting seafood ≥2/wk vs. never during the past year had 2.3 (95% confidence interval 1.9, 2.7), 1.4 (1.2, 1.6), 6.0 (4.6, 7.8) and 1.7 (1.4, 2.0) times higher ( p-trend <0.001) concentrations of total arsenic, DMA, arsenobetaine and total arsenic minus arsenobetaine, respectively. In participants without detectable arsenobetaine and in analyses adjusted for arsenobetaine, seafood consumption in the past year was not associated with total arsenic or DMA concentrations in urine. Conclusion Seafood intake was a major determinant of increased urine concentrations of total arsenic, DMA, arsenobetaine and total arsenic minus arsenobetaine in the US population. Epidemiologic studies that use total arsenic, DMA, the sum of inorganic arsenic, methylarsonate and DMA, and total arsenic minus arsenobetaine as markers of inorganic arsenic exposure and/or metabolism need to address seafood intake.

Direct determination of arsine in gases by inductively coupled plasma–dynamic reaction cell–mass spectrometry

Reliable determination of arsine (AsH 3) in gases is of great importance due to stringent regulations associated with health, safety and environmental issues. It is, however, challenging for an analyst to determine trace airborne arsine concentrations without specifically designed collection procedures using adsorption, desorption, dissolution or impinging techniques. To circumvent such technical barrier, we have newly developed a direct analytical method, characterized by introduction of an arsine gas sample into stable plasma stream, followed by gas-phase oxidation of arsine with molecular oxygen in a dynamic reaction cell (DRC) equipped within the inductively coupled plasma–mass spectrometry (ICP/MS) system, followed by subsequent detection of AsO + ion. This preliminary work used trace arsine concentrations (161 μg m −3, 322 μg m −3, and 645 μg m −3) gravimetrically prepared in N 2 balance. The proposed method was optimized for the important experimental parameters such as the flow rates of the reaction gas, the arsine sample, and the carrier gas. This method was then validated by demonstrating good figure-of-merits including the low limit of detection (0.10 μg m −3), good linearity ( r 2 > 0.9915), low measurement uncertainty (0.66%), and high speed of analysis (<6 min). The proposed method is expected to be potentially applicable to the determination of arsine in real workplace air after appropriate modifications are made.

Determination of glyphosate and AMPA in surface and waste water using high-performance ion chromatography coupled to inductively coupled plasma dynamic reaction cell mass spectrometry (HPIC–ICP–DRC–MS)

A novel method employing high-performance cation chromatography in combination with inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) for the simultaneous determination of the herbicide glyphosate (N-phosphonomethylglycine) and its main metabolite aminomethyl phosphonic acid (AMPA) is presented. P was measured as (31)P(16)O(+) using oxygen as reaction gas. For monitoring the stringent target value of 0.1μg L(-1) for glyphosate, applicable for drinking and surface water within the EU, a two-step enrichment procedure employing Chelex 100 and AG1-X8 resins was applied prior to HPIC-ICP-MS analysis. The presented approach was validated for surface water, revealing concentrations of 0.67μg L(-1) glyphosate and 2.8μg L(-1) AMPA in selected Austrian river water samples. Moreover, investigations at three waste water-treatment plants showed that elimination of the compounds at the present concentration levels was not straightforward. On the contrary, all investigated plant effluents showed significant amounts of both compounds. Concentration levels ranged from 0.5-2μg L(-1) and 4-14μg L(-1) for glyphosate and AMPA, respectively.

Determination of chromium in airborne particulate matter by inductively coupled plasma dynamic reaction cell mass spectrometry

A modified three-stage microwave-assisted digestion protocol for chromium analysis in airborne total suspended particulate matter (TSP) with recovery > 90%, which utilizes inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS), has been developed and validated. Similar results were obtained for 52Cr and 53Cr analyses, with a method detection limit of 950 ng g(-1) (0.38 ng ml(-1)) for 52Cr. The method is applicable to the analyses of a suite of other elements in TSP, particularly for Al, Fe and Ti. A comparison of the method with various other extraction and digestion procedures has been given. Our results highlight the difficulties in Cr analyses. Concentrations of Cr in TSP at two urban sites in Hong Kong were determined in the range from 5.8-32.3 ng m(-3), with an average value of 13.2 ng m(-3). The mean concentration of Cr was found to be 10.7 ng m(-3) at a residential/commercial site and 15.6 ng m(-3) at a mixed industrial/residential/commercial site. Ambient Cr concentrations did not reach maxima at vehicular rush-hour times but peaked at combined vehicle and industrial activity. The Cr concentrations at each site were strongly correlated with the total PM10 (particulate matter with aerodynamic diameter < 10 microm) concentrations and inversely correlated with ambient relative humidity. Relationships of Cr with ambient pollutant gases and other elements in TSP suggest that there is no single source which dominates the concentration of Cr in aerosol. There are several contributing sources and their relative proportions vary at different locations.

Eliminating molybdenum oxide interference in urine cadmium biomonitoring using ICP-DRC-MS

A new method for urine cadmium biomonitoring is presented. It uses inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) to eliminate molybdenum-based polyatomic interferences. The method began to be used in the National Health and Nutrition Examination Survey (NHANES) starting with the 2003–2004 survey cycle. Removal of moybdenum-based polyatomic interferences was found to reduce observed urine cadmium concentrations by a signficant amount, 37% at the 50th percentiles, for a subset (N = 2066) of NHANES 2003–2004 urine specimens. To avoid creating an artificial shift in NHANES data with the introduction of this method, urine cadmium results for survey cycles 1999–2000 and 2001–2002 were republished (http://www.cdc.gov/exposurereport/report.htm,1http://www.cdc.gov/nchs/datawh.htm2) after mathematical adjustment correcting for the bias on the basis of their previously determined molybdenum concentrations. Data supporting this mathematical adjustment are presented in this article. Blood cadmium data presented here show that at the normal levels of blood molybdenum, no significant molybdenum-based interferences are observed.

Speciation analysis of arsenic and selenium compounds in environmental and biological samples by ion chromatography–inductively coupled plasma dynamic reaction cell mass spectrometer

An inductively coupled plasma mass spectrometer (ICP-MS) was used as an ion chromatographic (IC) detector for the speciation analysis of arsenic and selenium. The arsenic and selenium species studied included arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), selenite [Se(IV)] and selenate [Se(VI)]. Gradient elution using (NH 4) 2CO 3 and methanol at pH 9 allowed the chromatographic separation of all species in less than 12 min. Effluents from the IC column were delivered to the nebulization system of ICP-DRC-MS for the determination of arsenic and selenium. The potentially interfering 38Ar 40Ar + and 40Ar 40Ar + at the selenium masses m/ z 78 and 80 were reduced in intensity by approximately 3 orders of magnitude by using 0.6 mL min −1 CH 4 as reactive cell gas in the DRC while an Rpq value of 0.3 was used. Meanwhile, arsenic was determined as the adduct ion 75As 12CHH + at m/ z 89, which is more sensitive than 75As. The limits of detection for arsenic and selenium were in the range of 0.002–0.01 ng mL −1 and 0.01–0.02 ng mL −1, respectively, based on peak height. The relative standard deviation of the peak areas for five injections of 5 ng mL −1 As and Se mixture was in the range of 2–4%. The concentrations of arsenic and selenium species have been determined in urine samples collected locally. The major As and Se species in urines were AsB, DMA and probably selenosugar at concentration of 20–40, 15–19 and 17–31 ng mL −1, respectively. The recoveries were in the range of 94–105% for all the determinations. This method has also been applied to determine various arsenic compounds in two fish samples. In this study, a simple and rapid microwave-assisted extraction method was used for the extraction of arsenic compounds from fish. The arsenic species were quantitatively leached with an 80% v/v methanol solution in a focused microwave field during a period of 5 min.

Water-Soluble and Total Sulfur in Particulate Matter Determined by Inductively Coupled Plasma Dynamic Reaction Cell Mass Spectrometry (ICP-DRC-MS)

Environmental Context.Sulfate in particulate matter is usually collected by a high-volume air sampler and analysed as a soluble extract by ion chromatography. The use of an inductively coupled plasma mass spectrometer fitted with a dynamic reaction cell enables not only the water-soluble, but also the total sulfate to be determined at the same time as the analyses of metal ions. Results from Hong Kong show that sulfate is strongly correlated with crustal species in particulate matter. Abstract.An instrumental method has been developed for the determination of sulfur in particulate matter using inductively coupled plasma dynamic reaction cell mass spectrometry. The reaction gas O2 was employed to convert S+ into the diatomic species SO+, and analysed at two different mass-to-charge ratios. The limit of detection for the 32S16O+ determination is ~1 ng S m–3. The method has the advantages that not only soluble sulfur (as commonly analysed by ion chromatography) but also total sulfur can be determined on the same instrument as many metal species. The mean values (± standard deviations) for a spring sampling program of particulate matter of diameter less than 10 μm (PM10) in Hong Kong (n = 13) for soluble and total S were 5.2 ± 1.2 μg m–3 and 5.5 ± 1.3 μg m–3 respectively. These values are quite low owing to a predominantly easterly airstream. Sulfur in PM10 is strongly correlated with the crustal species Ca, Al and Mn.

Laser ablation–inductively coupled plasma–dynamic reaction cell–mass spectrometry for the multi-element analysis of polymers

In this work, the potential of laser ablation–inductively coupled plasma–mass spectrometry for the fast analysis of polymers has been explored. Different real-life samples (polyethylene shopping bags, an acrylonitrile butadiene styrene material and various plastic bricks) as well as several reference materials (VDA 001 to 004, Cd in polyethylene) have been selected for the study. Two polyethylene reference materials (ERM-EC 680 and 681), for which a reference or indicative value for the most relevant metals is available, have proved their suitability as standards for calibration. Special attention has been paid to the difficulties expected for the determination of Cr at the μg g − 1 level in this kind of materials, due to the interference of ArC + ions on the most abundant isotopes of Cr. The use of ammonia as a reaction gas in a dynamic reaction cell is shown to alleviate this problem, resulting in a limit of detection of 0.15 μg g − 1 for this element, while limiting only modestly the possibilities of the technique for simultaneous multi-element analysis. In this regard, As is the analyte most seriously affected by the use of ammonia, and its determination has to be carried out in vented mode, at the expense of measuring time. In all cases studied, accurate results could be obtained for elements ranging in content from the sub-μg g − 1 level to tens of thousands of μg g − 1 . However, the use of an element of known concentration as internal standard may be needed for materials with a matrix significantly different from that of the standard (polyethylene in this work). Precision ranged between 5% and 10% RSD for elements found at the 10 μg g − 1 level or higher, while this value could deteriorate to 20% for analytes found at the sub-μg g − 1 level. Overall, the technique evaluated presents many advantages for the fast and accurate multi-element analysis of these materials, avoiding laborious digestion procedures and minimizing the risk of analyte losses due to the formation of volatile compounds.