Dynamic Reaction Cell Inductively Coupled Plasma Mass Spectrometry Research Articles

The Relationship between Metal Exposure and Chronic Obstructive Pulmonary Disease in the General US Population: NHANES 2015-2016.

The effects of metal on pulmonary function are inconsistent, and abnormal distribution of metals can decrease lung function. However, the effects of metals exposure on chronic obstructive pulmonary disease (COPD) are still unclear. This study aims to explore the relationship between metal exposure and COPD risk. Cross-sectional data from the National Health and Nutrition Survey (NHANES) 2015–2016 was analyzed. Inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) was used to measure the metals concentration in the blood. The multiple linear regression and restricted cubic spline (RCS) were used to analyze the relationship between metals exposure and COPD risk. In this study, 1399 participants were included, of which 107 participants were diagnosed with COPD using self-reported chronic bronchitis, emphysema, and COPD. The second and third tertiles of copper increased the COPD risk by 1.98-fold (95% CI: 1.08–3.62) and 2.43-fold (95% CI: 1.32–4.48) compared with the first tertile, using p = 0.005 for the trend after adjusting for the covariates. RCS showed a positive linear correlation between copper and COPD risk (p = 0.006 for overall association) in all participants. When stratified by sex, the multi-factor analysis showed that the third tertile of copper increased male’s COPD risk by 3.42-fold (95% CI: 1.52–7.76), with p = 0.003 for the trend, and RCS also showed a positive linear correlation (p = 0.013 for overall association). Although RCS showed that selenium can reduce the COPD risk (p = 0.008 for overall association) in males, an association between selenium and COPD was not observed (p > 0.05). Our findings suggest that a high concentration of copper may increase COPD risk in males in the general US population, and more research is needed to explore its possible mechanism of action.

Serum Copper and Zinc Levels and Colorectal Cancer in Adults: Findings from the National Health and Nutrition Examination 2011-2016.

Several studies have indicated an association between serum copper and zinc levels and colorectal cancer, but results were controversial. This study assessed the association of serum copper, zinc, and copper/zinc ratio with colorectal cancer in US adults aged 20years and older through the use of National Health and Nutrition Examination Survey (NHANES) 2011-2016 data. Serum concentrations of copper and zinc were measured using inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS). Odds ratios with 95% confidence intervals (ORs with CIs) were calculated for serum copper, zinc, and copper/zinc ratio by multivariate logistic regression. A total of 4663 participants (2320 males and 2343 females) with 24 colorectal cancer patients were included in the analyses. We did not observe a statistically significant association between serum copper level and colorectal cancer (top vs bottom quartile multivariate OR 1.71; 95% CI, 0.37-7.88; P for trend = 0.429). In addition, serum zinc level was also not significantly associated with colorectal cancer (top vs bottom quartile multivariate OR 0.72; 95% CI, 0.12-4.27; P for trend = 0.346). While in the age- and gender-adjusted model, there seemed to be a trend that participants with higher copper/zinc ratio level had higher odds of colorectal cancer than participants with lower copper/zinc ratio level; no statistically significant association was observed in multivariate-adjusted models. Our findings did not support a significant association between serum copper and zinc level and colorectal cancer risk in the general US population. Furthermore, large longitudinal studies should be needed to confirm these findings.

Determination of Cr(VI) in rice using ion chromatography inductively coupled plasma mass spectrometry

Determination of Cr(VI) in rice is reported using ion chromatography (IC) and dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS). Cr(VI) is separated from other Cr species within 4.5 min using NH4NO3 solution at pH 8.8 as mobile phase. Spectral interferences on 52Cr+ are minimized with NH3 in DRC. The detection limit of (LOD) Cr(VI) is 0.06 ng mL−1. This methodology is utilized for the determination of Cr(VI) in different rice samples and can also be applied for screening of rice for toxicity with respect to Cr. The Cr species are leached from rice powder into 5% (v/v) tetramethyl ammonium hydroxide (TMAH) solution in an ultrasonic bath. The extracts are analyzed by IC-DRC-ICP-MS for Cr(VI). Spike recoveries of Cr(VI) are 98–102% and precision between sample replicates is better than 6.3%. No Cr(III) is converted to Cr(VI) during extraction. Cr(VI) is present in all the rice samples analyzed.

Assessing the stability of Cd, Mn, Pb, Se, and total Hg in whole human blood by ICP-DRC-MS as a function of temperature and time

BackgroundComprehensive information on the effect of time and temperature storage on the measurement of elements in human, whole blood (WB) by inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS) is lacking, particularly for Mn and Se. MethodsHuman WB was spiked at 3 concentration levels, dispensed, and then stored at 5 different temperatures: -70 °C, −20 °C, 4 °C, 23 °C, and 37 °C. At 3 and 5 weeks, and at 2, 4, 6, 8, 10, 12, 36 months, samples were analyzed for Pb, Cd, Mn, Se and total Hg, using ICP-DRC-MS. We used a multiple linear regression model including time and temperature as covariates to fit the data with the measurement value as the outcome. We used an equivalence test using ratios to determine if results from the test storage conditions, warmer temperature and longer time, were comparable to the reference storage condition of 3 weeks storage time at −70 °C. ResultsModel estimates for all elements in human WB samples stored in polypropylene cryovials at −70 °C were equivalent to estimates from samples stored at 37 °C for up to 2 months, 23 °C up to 10 months, and −20 °C and 4 °C for up to 36 months. Model estimates for samples stored for 3 weeks at −70 °C were equivalent to estimates from samples stored for 2 months at −20 °C, 4 °C, 23 °C and 37 °C; 10 months at −20 °C, 4 °C, and 23 °C; and 36 months at −20 °C and 4 °C. This equivalence was true for all elements and pools except for the low concentration blood pool for Cd. ConclusionsStorage temperatures of −20 °C and 4 °C are equivalent to −70 °C for stability of Cd, Mn, Pb, Se, and Hg in human whole blood for at least 36 months when blood is stored in sealed polypropylene vials. Increasing the sample storage temperature from −70 °C to −20 °C or 4 °C can lead to large energy savings. The best analytical results are obtained when storage time at higher temperature conditions (e.g. 23 °C and 37 °C) is minimized because recovery of Se and Hg is reduced. Blood samples stored in polypropylene cryovials also lose volume over time and develop clots at higher temperature conditions (e.g., 23 °C and 37 °C), making them unacceptable for elemental testing after 10 months and 2 months, respectively.

Lead isotopic analysis of Antarctic snow by quadrupole ICP-MS using a total-consumption sample introduction system

Measurement of lead isotope ratios in snow samples using inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS) at a low sample consumption rate was thoroughly studied.

Dynamic reaction cell inductively couple plasma-mass spectrometry optimization for seawater analysis

A direct method for dynamic reaction cell inductively coupled plasma- mass spectrometry (DRC-ICP-MS) trace mineral elements determination in seawater was optimized by Experimental Statistical Design. Five instrumental parameters, such as radiofrequency, sample, nebulizer and reaction gas flows, rejection parameter q and axial field voltage were studied. A Plackett-Burman design was used for screening the most important parameters and the most significant ones were optimized with a Central composite design. Fifteen elements and different isotopes for some of these were considered through the study. The optimization was achieved by using three different reaction gases (NH3, CH4 and O2). The optimized method was used for the quantification of trace minerals in a certified seawater sample. The standard mode was adequate for the quantification of those elements that have a reduced number of interferences like 111Cd and 238U. However, the best results were obtained employing ICP-MS in NH3-DRC mode which allowed the simultaneous determination of elements like 51V, 55Mn, 58Ni, 68Zn and 238U, which can be determined in the reference sample with an accuracy error lower than 10% and 95Mo determined with an accuracy error of 15%. The use of CH4-DRC was restricted to quantify 111Cd with an error of 16%. The use of O2-DRC was suitable for determining 55Mn, 66Zn with errors lower than 3% and 51V, when monitored it in oxide form 67VO, with an accuracy error of 2%. O2-DRC is the single DRC mode that allowed a satisfactory quantification of 75As, with an error of 33% for a very low concentration, compared to other analysis mode in the direct analysis of seawater. Additionally Pb can be quantitatively recovered from spiked samples using NH3 and O2-DRC modes.

Serum Trace Elements and Electrolytes Are Associated with Fasting Plasma Glucose and HbA1c in Postmenopausal Women with Type 2 Diabetes Mellitus.

The primary aim of the research was to assess the level of trace elements and electrolytes in serum of postmenopausal diabetic women. Sixty-four postmenopausal women with type 2 diabetes mellitus (DM2) and 64 age- and body mass index-matched controls were examined. Serum trace elements were assessed using inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS). Fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c) levels were evaluated using Randox kits. The obtained data demonstrate that DM2 patients were characterized by 42 and 34% higher FPG and HbA1c levels, respectively (p<0.001). The level of Cu and Se in diabetic postmenopausal women was increased by 10 and 15% in comparison to the respective control values (p=0.002 and <0.001). Serum Mn, Zn, and Ni concentrations were lower than the control ones by 32% (p=0.003), 8% (p=0.003), and 23% (p=0.046), respectively. FPG and HbA1c levels directly correlated with serum Se (p<0.001) and Cu (p=0.014 and p=0.028) concentrations and inversely related to Zn (p<0.001) and Tl (p=0.023 and p=0.029) levels. Multiple regression analysis demonstrated a significant association between serum Zn and Se and FPG and HbA1c levels. It is proposed that Zn and Se play an important role in DM2 pathogenesis. Further studies are required to assess the intimate mechanisms of the observed differences.

A novel methodology for rapid digestion of rare earth element ores and determination by microwave plasma-atomic emission spectrometry and dynamic reaction cell-inductively coupled plasma-mass spectrometry

Short-wavelength infrared radiation has been successfully applied to accelerate the acid digestion of refractory rare-earth ore samples. Determinations were achieved with microwave plasma-atomic emission spectrometry (MP-AES) and dynamic reaction cell – inductively coupled plasma-mass spectrometry (DRC-ICP-MS). The digestion method developed was able to tackle high iron-oxide and silicate matrices using only phosphoric acid in a time frame of only 8min, and did not require perchloric or hydrofluoric acid. Additionally, excellent recoveries and reproducibilities of the rare earth elements, as well as uranium and thorium, were achieved. Digestions of the certified reference materials OREAS-465 and REE-1, with radically different mineralogies, delivered results that mirror those obtained by fusion processes. For the rare-earth CRM OKA-2, whose REE data are provisional, experimental data for the rare-earth elements were generally higher than the provisional values, often exceeding z-values of +2. Determined values for Th and U in this reference material, for which certified values are available, were in excellent agreement.

Trace metal levels in serum and urine of a population in southern Brazil

This study aimed to evaluate serum and urine concentrations of several trace metals of a non-directly exposed population in southern Brazil and establish reference values. Serum and urine samples were obtained from 240 volunteers (175 males and 65 females, age ranging from 18 to 74 years old). Levels of arsenic, chromium, cobalt, copper, lead, nickel, manganese and zinc were determined by means of dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS). Comparison between genders resulted in no significant difference for all metals but serum copper, as concentrations are higher in females than males. For most metals assessed, a negative correlation between serum concentrations and age was found, but no significant correlation was found between urine concentrations and age.

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.

Determination of Cr(vi) in cosmetic products using ion chromatography with dynamic reaction cell-inductively coupled plasma-mass spectrometry (DRC-ICP-MS)

The chromium(vi) salts are possible contaminants of the chromium(iii) pigments used as colorants in face powder and eye shadow preparations.

Exposure to heavy metals due to pesticide use by vineyard farmers.

To statistically analyze serum heavy metal levels in biological samples obtained from vineyard workers from southern Brazil and check for heavy metal exposure due to pesticide use. Serum samples were obtained from 54 farmers and 108 healthy unexposed individuals. Samples from the same farmers were obtained at three different time points over a 1-year period. Levels of lead, arsenic, nickel, zinc, manganese and copper were determined for each sample using dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS). All results were statistically analyzed using the nonparametric Kruskal-Wallis test (followed by Dunn's post hoc test). Results showed that serum heavy metal levels in farmers were twofold to fourfold higher than in controls. This difference was found for all heavy metals tested and was significant (p < 0.05). Serum metal levels among the farmers also correlated with the frequency of use of pesticides at a specific time of year, which varied according to seasonal conditions influencing the need for pesticide application. It can be concluded that in the vineyard region assessed, farmers were more susceptible to heavy metal exposure due to pesticide use.

Plasma-based determination of inorganic contaminants in waste of electric and electronic equipment after microwave-induced combustion

A systematic study was performed for the determination of inorganic contaminants in polymeric waste from electrical and electronic equipment (EEE) for achieving an efficient digestion to minimize interferences in determination using plasma-based techniques. The determination of As, Br, Cd, Co, Cr, Cu, Ni, Pb, Sb, and Zn by inductively coupled plasma mass spectrometry (ICP-MS) and also by inductively coupled plasma optical emission spectrometry (ICP OES) was carried out after digestion using microwave-induced combustion (MIC). Arsenic and Hg were determined by flow-injection chemical vapor generation inductively coupled plasma mass spectrometry (FI-CVG-ICP-MS). Dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) with ammonia was also used for Cr determination. The suitability of MIC for digestion of sample masses up to 400mg was demonstrated using microcrystalline cellulose as aid for combustion of polymers from waste of EEEs that usually contain flame retardants that impair the combustion. The composition and concentration of acid solutions (HNO3 or HNO3 plus HCl) were evaluated for metals and metalloids and NH4OH solutions were investigated for Br absorption. Accuracy was evaluated by comparison of results with those obtained using high pressure microwave-assisted wet digestion (HP-MAWD) and also by the analysis of certified reference material (CRM) of polymer (EC680k—low-density polyethylene). Bromine determination was only feasible using digestion by MIC once losses were observed when HP-MAWD was used. Lower limits of detection were obtained for all analytes using MIC (from 0.005μgg−1 for Co by ICP-MS up to 3.120μgg−1 for Sb by ICP OES) in comparison to HP-MAWD due to the higher sample mass that can be digested (400mg) and the use of diluted absorbing solutions. The combination of HNO3 and HCl for digestion showed to be crucial for quantitative recovery of some elements, as Cr and Sb. In addition, suitable agreement of Cr to CRM value was only obtained by mixing NH4Cl to samples before combustion. No statistical difference (95% confidence level) was observed between the results obtained for As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, and Zn by MIC and HP-MAWD methods. Agreement with certified values was better than 96% using MIC for all inorganic contaminants. Particularly for Br, MIC was the method of choice for digestion due to the possibility of using diluted alkaline solutions for analyte absorption. Based on the obtained results, MIC can be considered as a suitable method for digestion of polymers from waste of EEEs for further plasma based determination of inorganic contaminants.

Simultaneous determination of Se, trace elements and major elements in Se-rich rice by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) after microwave digestion

A quick and accurate method was devised to determine Se, As, Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr and Zn in Se-rich rice samples by microwave digestion and inductively coupled plasma-mass spectrometry (ICP-MS). Spectral interferences on Se were eliminated using methane as a reaction gas in the dynamic reaction cell (DRC). Rhodium was used as an internal standard to compensate for sample matrix effects. A rice-certified reference material (CRM) (GBW 10010) was used to verify the accuracy of the method. The method detection limits were 0.001–0.03mg/kg, analyte recoveries were 85–108% and precisions (RSDs) ranged from 2.1% to 5.8%. Correlation analysis showed that the Se concentrations in the Se-rich rice samples correlated well with the Cu concentrations (r=0.53, p<0.05).

Single-step procedure for trace element determination in synovial fluid by dynamic reaction cell-inductively coupled plasma mass spectrometry

A fast and single-step procedure for the dissolution of human synovial fluid in formic acid and further determination by dynamic reaction cell-inductively coupled plasma mass spectrometry (DRC-ICPMS) with a high-efficiency sample introduction system was developed. The samples were collected, treated and analyzed in the same screw-capped tubes. In order to overcome the effect of considerable carbon content, the sample introduction, nebulization and ICP operating conditions were carefully optimized. Furthermore, DRC technology with CH4 as reaction gas was used for the elimination of spectral interferences due to polyatomic ions. The effect of the sample matrix was evaluated and mitigated through comparison of direct calibration against aqueous standards, direct calibration in formic acid media and analyte addition calibration. The recommended procedure involved low dilution and low detection limits (from 0.003μgL−1 for U to 13.3μgL−1 for Ti) with adequate precision (from 0.6% for Co to 6.6% for Ti). The proposed method was successfully applied to determine 16 trace elements in concentrations from 0.03μgL−1 (Cd) to 88.2μgL−1 (Cu) in human synovial fluid samples.

Oxygenation Mechanism of Ions in Dynamic Reaction Cell ICP-MS

A dynamic reaction cell (DRC) is one of the most effective tools for eliminating spectral interferences caused by polyatomic molecules in inductively coupled plasma mass spectrometry (ICP-MS). Oxygen gas (O2), by producing oxygenated ions, is very effective in reducing some specific spectral interferences. In this study, the oxygenation of elemental ions (M(+)) in the DRC was investigated experimentally, and a new explanation for oxygenation based on the enthalpy changes in the oxygenating reactions is proposed. The enthalpy changes of each M(+) were calculated and the possibility of each reaction occurring was evaluated. The calculations were in good agreement with experimental observations. Theoretical and experimental results supported the hypothesis that the enthalpy changes (ΔH) of M(+)+ O2 → MO(+) + O and M(+) + O → MO(+) and the thermodynamic stability of M(+)-O are key factors controlling oxygenation of M(+) in the DRC.

Selenium speciation in paired serum and cerebrospinal fluid samples

Se speciation was performed in 24 individual paired serum and cerebrospinal fluid (CSF) samples from neurologically healthy persons. Strong anion exchange (SAX) separation, coupled to inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS), was employed. Species identification was done by standard matched retention time, standard addition and by size exclusion chromatography followed from SAX (2-D SEC-SAX-ICP-DRC-MS) and by SAX followed from CE-ICP-DRC-MS (2-D SAX-CE-ICP-DRC-MS). Limit of detection (LoD, 3×standard deviation (SD) of noise) was in the range of 0.026-0.031 μg/L for all investigated species and thus was set uniformly to 0.032 μg/L. Quality control for total Se determination was performed by analysing control materials "human serum" and "urine", where determined values met target values. Several Se species were found in both sample types having following median values (sequence: serum/CSF, each in μg Se/L): total Se, 58.39/0.86; selenoprotein P (SePP), 5.19/0.47; Se-methionine (SeM), 0.23/<LoD; glutathione peroxidase (GPx), 4.2/0.036; thioredoxinreductase (TrxR), 1.64/0.035; Se IV, 12.25/0.046; Se-human serum albumin (Se-HSA), 18.03/0.068. Other Se species, such as Se-cystine (SeC), Se VI and up to four non-identified compounds were monitored (if ever) only in very few samples usually close to LoD. Therefore, their median values were <LoD. Linear relationships based on median values provide information about Se-species passage across neural barriers (NB): SePP(-serum) is significantly correlated to total Se(-serum) when the latter was > 65 μg/L; however, SePP(-CSF) appeared independent of SePP(-serum). For Se-HSA(-serum) versus (vs.) Se-HSA(-CSF), a weak linear relationship was found (r(2)=0.1722). On the contrary, for anti-oxidative Se-enzymes, higher r (2) values were calculated: GPx(-serum) vs. GPx(-CSF), r(2)=0.3837; TrxR(-serum) vs. TrxR(-CSF), r(2)=0.6293. Q(-Se-species) values (= ratios of CSF(-Se-species)/serum(-Se-species)) were compared with the Q (-Alb) value (HSA(-CSF)/HSA(-serum)=clinical index of NB integrity) for deeper information about NB passage of Se species. The Q (-Se-HSA) value (3.8×10(-3)) was in accordance to the molecular mass dependent restriction at NB (Q(-Alb) at 5.25×10(-3)). Increased Q values were seen for TrxR (21.3×10(-3)) and GPx (8.3×10(-3)) which are not (completely) explained by molecular size. For these two anti-oxidative Se-enzymes (GPx, TrxR), we hypothesize that there might be either a facilitated diffusion across NB or they might be additionally synthesized in the brain.

Influence of serum selenium concentrations on hypertension

Selenium is an antioxidant micronutrient with potential associations with hypertension. Few studies have investigated the association of serum selenium concentrations with blood pressure and hypertension in countries with low dietary selenium intake such as Germany, with inconsistent findings. We undertook a cross-sectional analysis of participants in the Lipid Analytic Cologne (LIANCO) cohort. To reduce potential confounding, we restricted the analysis to 792 participants who were never smokers, who did not use antihypertensive medications, and who did not have diabetes or known atherosclerotic disease. Hypertension was defined as blood pressure at least 140 and/or at least 90 mmHg. About half of the cohort was diagnosed as hypertensive. Selenium was measured by inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS). Mean ± standard deviation (SD) serum selenium concentration was 68 ± 32 μg/l. The multivariable adjusted differences (95% confidence intervals) in blood pressure levels comparing the highest (>91.9 μg/l) to the lowest (≤ 42.8 μg/l) quartile of serum selenium were 5.2 (1.4 to 8.9), 2.8 (0.7 to 4.8), and 2.4 (-0.4 to 5.2) mmHg for systolic, diastolic, and pulse pressure, respectively (P for trend for all <0.003). The corresponding multivariable adjusted odds ratio for the presence of hypertension was 1.52 (0.98 to 2.36; P trend = 0.004). The data suggest that even in a population with very low serum selenium concentrations higher serum selenium concentrations are associated with higher blood pressure levels and a higher prevalence of hypertension. These findings call for careful evaluation of the effects of selenium on blood pressure endpoints in randomized clinical trials.

Hydrogen compounds formation of calcium in an ICP-DRC-MS

Isobaric ions overlap an isotope of interest in mass spectrometry, and an inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS) analysis also bears the same problem. In this research, processes of 40CaH+ formation and decreasing methods were studied. Plasma power was swept from 1300 W to 600 W to investigate 40CaH+ formation in the plasma. 1.90 × 10−4 of 40CaH+/40Ca+ with 1300 W decreased to 1.27 × 10−4 when 750 W of plasma power was applied. Deionized water of samples was replaced with heavy water to verify if 40CaH+ is formed in the interface part of the equipment. Normally NH3 gas is injected into the DRC to remove argide ions for a measurement of calcium samples in an ICP-DRC-MS, but we found NH3 contributes to form hydrogen compounds in the DRC by introducing a strontium sample, which is the same alkaline earth metal as calcium. 1.59 × 10−4 of 40CaH+/40Ca+ at 0.8 ml min−1 of NH3 cell gas decreased to 1.72 × 10−5 with 0.85 ml min−1 of additional O2cell gas injection. Results verify that hydrogen compounds made from NH3 in an ICP-DRC-MS could affect ultra trace isotope ratio analysis.

A comparison of clinical laboratory data for assigning a consensus value for manganese in a caprine blood reference material.

Biomonitoring for manganese (Mn) exposure is important due to its potential to cause adverse health effects. In this study, we investigate how different sample preparation methods (simple dilution, digestion, volumetric, gravimetric), calibration protocols (aqueous, blood-based, standard additions), and instrumental techniques affect Mn method bias and analytical imprecision. The techniques used included graphite furnace atomic absorption spectrometry (GFAAS), dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS), and sector field (SF-) ICP-MS. We analyzed NIST SRM 1643e Trace Elements in Water and SRM 1598a Inorganic Constituents in Animal Serum (both certified for Mn), and SRM 955c Toxic Metals in Caprine Blood - Level 1 (not certified for Mn). Various matrix effects in ICP-MS produced inaccurate results for SRM 1643e and discrepant results for SRM 955c. In the absence of a certified value for Mn in SRM 955c, we assigned a "consensus" value by combining data from the New York State Department of Health (NYS), the Centers for Disease Control and Prevention (CDC) and the Centre de toxicologie du Québec (CTQ). With this interlaboratory approach, we established an "all-lab" consensus value of 16.3 ± 0.8 μg L-1 based on data from DRC-ICP-MS with simple dilution sample preparation and blood-based calibration. We also assigned an "all-method" consensus value of 16.3 ± 0.9 μg L-1 based on GFAAS and SF-ICP-MS data from the NYS lab and the DRC-ICP-MS all-lab consensus value. Although the expanded uncertainty (U) calculated for the consensus values may not fully account for all sources of uncertainty, it does show the relative variation that might be expected from one study to the next for the determination of Mn in blood.