Plasma Mass Spectrometry Method Research Articles

Dominant Role of Silver Ions in Silver Nanoparticle Toxicity to a Unicellular Alga: Evidence from Luminogen Imaging.

Despite the extensive studies on silver nanoparticle (AgNP) toxicity, the contribution of released silver ions to the toxicity still remains debatable. This study investigated the toxicity of AgNPs with different sizes (20 and 60 nm) toward a phytoplankton Euglena gracilis, with a focus on evaluating the contributions of dissolved Ag to the toxicity by combining a newly developed aggregation-induced emission luminogen (AIEgen)-based imaging technique and a traditional inductively coupled plasma mass spectrometry (ICP-MS) method. Smaller AgNPs, which dissolved much faster, exhibited greater toxicity, as evidenced by lower 50% growth inhibition concentration (EC50). However, the average Ag+ concentration at each EC50 was comparable to the EC50 of AgNO3, and similar subcellular Ag distribution patterns were observed in both AgNPs and AgNO3 exposed algae. More silver ions were internalized in algae treated with smaller AgNPs. With the application of luminogen imaging technology, we for the first time demonstrated that few Ag(I) were presented intracellularly in algae exposed to AgNPs when any released Ag in the medium was complexed by cysteine. Ag(I) was mainly distributed in cellular debris, organelles, and metal-rich granules fractions. No conclusive evidence for AgNP internalization was documented. Our results strongly suggested that Ag+ released from AgNPs extracellularly dominated the AgNP toxicity. The findings of this work provide new and useful insight into the toxicity of AgNPs in aquatic environments.

U-Pb Geochronology of Apatite and Calcite at The Ernest Henry Deposit, NW Queensland; Implications for Hydrothermal Evolution and Ore Genesis

The Ernest Henry deposit represents the largest known Iron Oxide Copper Gold (IOCG) deposit in the Eastern Succession of the Mount Isa inlier. The orebody consists of a structurally controlled pipe-like breccia hosted in complexly altered Proterozoic volcanics with mineralization occurring post-peak metamorphism during a regional transpressional deformational event (D3). Ore formation was controlled by the mixing of magmatic, metamorphic and basal fluids, resulting in the precipitation of chalcopyrite, pyrite, calcite, quartz, magnetite and accessory gold. Coarse-grained apatite is present as an accessory mineral in areas of high sulphide mineralization and in shear zones adjacent to the orebody. The paragenesis and relative timing of the alteration and mineralisation stages have been well constrained by previous workers. However, advances in U-Pb geochronology via the in-situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) method means that for the first time apatite and calcite from the ore body and adjacent structures may be suitable for age dating. This project will use an established apatite dating technique and aims to develop a calcite dating technique to provide dates for individual paragenetic stages. These time constraints will improve the current understanding hydrothermal evolution and ore genesis at Ernest Henry. As calcite is a common accessory mineral in ore deposits, this technique could be widely implemented to date mineralization events and may allow hydrothermal events at different deposits to be linked.

Discrimination of the Sicilian Prickly Pear (Opuntia Ficus-Indica L., CV. Muscaredda) According to the Provenance by Testing Unsupervised and Supervised Chemometrics.

Different multivariate techniques were tested in an attempt to build up a statistical model for predicting the origin of prickly pears (Opuntia ficus-indica L., cv. Muscaredda) from several localities within the Sicilian region. Specifically, two areas known for producing fruits marked respectively by TAP (traditional agri-food product) and PDO (protected designation of origin) brands, and three sites producing non-branded fruits, were considered. A validated inductively coupled plasma mass spectrometry (ICP-MS) method allowed to obtain elemental fingerprints of prickly pears, which were subsequently elaborated by unsupervised tools, such as hierarchical clustering analysis (HCA) and principal component analysis (PCA), and supervised techniques, such as stepwise-canonical discriminant analysis (CDA) and partial least squares-discriminant analysis (PLS-DA). With the exception of HCA, which was not enough powerful to correctly cluster all selected samples, PCA successfully investigated the effect of subregional provenance on prickly pears, thus, differentiating labeled products from the non-labeled counterpart. Also, stepwise CDA and PLS-DA allowed to build up reliable models able to correctly classify 100% of fruits on the basis of the production areas, by exploiting a restricted pool of metals. Both statistical models, including unsupervised (PCA) and supervised techniques (stepwise CDA or PLS-DA), may guarantee the provenance of prickly pears protected by quality labels and safeguard producers and consumers. PRACTICAL APPLICATION: Based on elemental analysis and chemometrics, the reliable traceability models herein proposed, could be applied to commercial Sicilian prickly pears protected by TAP and PDO logos to guarantee their provenance and, at the same time, to safeguard producers and consumers.

Analysis of Hazardous Elements in Children Toys: Multi-Elemental Determination by Chromatography and Spectrometry Methods.

This paper presents the results of determination of hazardous metal (Cd, Cu, Cr, Hg, Mn, Ni, Pb, Zn) and metalloid (As, Sb) levels in toys available in the Polish market. Two independent sample preparation methods were used to determine the concentration and content of the metals and metalloids. The first one is defined by the guidelines of the EN-71 standard and undertook extraction in 0.07 mol/L HCl. This method was used to conduct speciation analysis of Cr(III) and Cr(VI), as well as for the determination of selected metals and metalloids. The second method conducted mineralization in a HNO3 and H2O2 mixture using microwave energy to determine the content of metals and metalloids. Determination of chromium forms was made using the high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method, while those of metals and metalloids were made using the ICP-MS technique. Additionally, in order to determine total content of chromium in toys, an energy dispersive X-ray fluorescence spectrometer (EDX) was used. The results of the analyses showed that Cr(VI) was not detected in the toys. In general, the content of heavy metals and metalloids in the studied samples was below the migration limit set by the norm EN-71.

Determination of iodine in geothermal water samples – preliminary ICP-MS method validation results

Abstract Iodine is a microelement which occurs in natural water in different concentrations dependent on water type, origin and total dissolved solids concentration. The objects of research were natural geothermal water. In this paper, the fitness of the inductively coupled plasma mass spectrometry (ICP-MS) method for iodine determination in water with higher temperatures was tested and selected methodological problems were discussed. Basic method parameters (precision, accuracy, linearity, uncertainty) were determined. Calculated statistical parameters of the validated method fulfil the assumed criteria. The received results (correlation coefficient equal to 0.999) show that the linearity of the ICP-MS method is good. The accuracy was expressed as recovery (R) and according to the literature is at an acceptable level. The results of precision assessments (RSD) also correspond to the literature data.

Lead Environmental Pollution and Childhood Lead Poisoning at Ban Thi Commune, Bac Kan Province, Vietnam.

Lead poisoning is a public health problem in many areas of the world. Children are at particularly high risk for adverse effects of lead exposure; even at low concentrations, lead can affect physical, mental, and behavioral development. Children living near lead-zinc mines are at high risk for environmental lead poisoning, especially the contaminated soil. We conducted a cross-sectional descriptive study in Ban Thi Commune, northern Vietnam. 195 children (92,9% participation) aged 3-14 years old (average: 7.69 ± 2.90) were randomly selected from a list of all children prepared by the village health collaborators. 109 (55.90%) were boys and 86 (44.10%) were girls. The research measures were the lead concentration in native soil and the children's total blood lead concentration determined by the inductively coupled plasma-mass spectrometry (ICP-MS) method. The results showed that lead content in soil was many times higher than American Environmental Protection Agency and Vietnam standards (average 2980.23 ± 6092.84 mg/kg dry weight of soil (range 80.05 – 33820.62)). Average blood lead levels for children were 15.42 ± 6.45 μg/dL (95% CI: 14.50 -16.33 μg/dL). The percentage of children with lead levels >10 μg/dL (value considered to be lead poisoning for children according to the Ministry of Health of Vietnam) was 79.49% of the total number of children. None of the children in this study had blood lead level (BLL) that required chelation treatment according to Vietnam MOH guideline (BLL ≥45 μg/dL). There is weakly evidence that lead exposure relates to the physical development of children. Children with low lead concentrations (less than 10 μg/dL) had height and weight of 1.47-3.51 cm and 1.19-2.81 kg, greater than those with BLL >10 μg/dL (p>0.05).

Heavy metals in maternal and cord blood in Beijing and their efficiency of placental transfer

This study aimed to determine the effect of exposure to heavy metals in pregnant women in Beijing, China. We also evaluated the association of these heavy metals with birth weight and length of newborns. We measured the levels of 10 heavy metals, including lead (Pb), titanium (Ti), manganese (Mn), nickel (Ni), cadmium (Cd), chromium (Cr), antimony (Sb), stannum (Sn), vanadium (V), and arsenic (As), in 156 maternal and cord blood pairs. An inductively coupled plasma mass spectrometry method was used for measurement. Pb, As, Ti, Mn, and Sb showed high detection rates (>50%) in both maternal and cord blood. Fourteen (9%) mothers had blood Pb levels greater than the United States Center for Disease Control allowable threshold limit for children (50 μg/L). In prenatal exposure to these heavy metals, there was no significant association between any heavy metal and birth weight/length. Moreover, we estimated the placental transfer efficiency of each heavy metal, and the median placental transfer efficiency ranged from 49.6% (Ni) to 194% (Mn) (except for Cd and Sn). The level and detection rate of Cd in maternal blood were much higher than that in cord blood, which suggested that Cd had difficulty in passing the placental barrier. Prospective research should focus on the source and risk of heavy metals in non-occupationally exposed pregnant women in Beijing.

Development of two Explosive Candidate Reference Materials: Certification of Metallic Impurities in LLM-105 and FOX-7

Explosive reference materials are significant to traceability analysis, quality control and measurement of energetic materials applied in modern weapon system. In the field of engineering-oriented application, LLM-105 and FOX-7 were proved that they had a promising prospect in used extensively as insensitive high energetic ingredients in munitions. Certification of metallic impurities in LLM-105 and FOX-7 was achieved by the microwave digestion-assistant inductively coupled plasma-mass spectrometry method. The contents of metallic impurities, including Na, K, Ca, Cr, Ni, Fe, Mg, Al, Co, Cu and Zn, in several LLM-105 and FOX-7 samples were accurately detected under the optimal conditions. And the detected results suggested that recrystallization was an effective method for high-purity explosive reference materials. This study could be helpful for the development of LLM-105 and FOX-7 candidate reference materials.

Determination of 16 heavy metal elements and 16 rare earth elements in Ya’an tibet tea by ICP-MS

The contents of 16 heavy metal elements such as As,Be,Co,Cr,Cu,Ga,Li,Ni, Sr,V,Zn,Ag,Cd,Cs,Bi, Pb and 16 rare earth elements such as Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,Yb, Lu were analyzed, simultaneously and effectively by inductively coupled plasma-mass spectrometry (ICP-MS) method with high pressure digestion and Rh, Re as the internal standard elements. The linear correlation coefficient of each element standard curve was 0.9919- 0.9999; the detection limit of each element is 0.0003 ug/L −0.2164 ug/L; the daily and daytime deviation of each element was lower; the average recoveries were between 93.39% −110.99%, RSD was less than 7.49%. The results showed that the average content of Zn was the highest to be (32.833±0.993) mg/kg, followed by Cu, Sr and Ni, which were significantly higher than those of other 28 elements. The total amount of rare earth in Ya’an was 0.588 mg/kg −3.161 mg/kg, The average content of Ce was the highest, followed by La, Sc, Nd and Y, the total amount of rare earth total 83.16%−86.15%, the average content of Lu was the lowest. The proportion of each element in the soil, different tea varieties on the absorption and enrichment of various elements, application of fertilizer and pesticide in tea garden resulted in the great differences of each element content.

Major and trace elements in meimechites – rarely occurring volcanic rocks: developing optimal analytical strategy

The determination of the chemical composition of meimechites – which are unique and rarely occurring ultra-high MgO igneous rocks – can be complicated due to their porphyric structure, the presence of acid-insoluble minerals, and wide variation of major and trace element contents. In the present study the optimal analytical strategy based on a combination of X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) methods was suggested for the determination of the elemental composition of meimechites. The preparation of glass beads using a lithium tetraborate and metaborate mixture proved to be suitable for the XRF determination of major oxides. A comparative study of the sample decomposition procedures for the determination of trace elements by ICP-MS clearly showed that fusion with lithium metaborate was the most appropriate sample preparation technique for complete digestion of meimechites. The open beaker HF-HNO 3 -HClO 4 acid digestion was insufficient because the results for Nb, Ta, V, Zr, Cr and Hf were underestimated by 20–80% compared to those determined using the fusion method due to the presence in the rock samples of acid-resistant accessory minerals. It is shown that using analytical data from acid digestion may lead to erroneous interpretation of geochemical data. Supplementary material: Comparing the results obtained by ‘wet chemistry’ and XRF methods; ICP-MS data for meimechite samples; ICP-MS analysis of reference materials are available at https://doi.org/10.6084/m9.figshare.c.4226786

A novel combined countercurrent chromatography – inductively coupled plasma mass spectrometry method for the determination of ultra trace uranium and thorium in Roman lead

The concentration of uranium and thorium in lead shields, which are used in underground particle physics research, should be monitored at sub-ppt levels. A combination of extraction chromatography and inductively coupled plasma mass spectrometry can resolve this analytical task. However, a multi-step complicated separation procedure and clean room are required. Besides, the recovery yields for U and Th do not exceed 80% and 60%, correspondingly. We propose an alternative approach. U and Th were pre-concentrated and separated from Pb by countercurrent chromatography, which is a support-free liquid-liquid chromatography. A series of two-phase extraction systems were tested. Under the optimized conditions, U and Th were extracted using a system 1 M HNO3/0.01 M tetraphenylmethylenediphosphine dioxide in chloroform and then eluted by 0.01 M aqueous solution of etidronic acid and determined by inductively coupled plasma mass spectrometry. The separation is performed in one chromatographic run, takes less than 1 h, and provides the quantitative recovery of U and Th. The limits of detection are 3 and 1 ppt for U and Th, correspondingly. The concentrations of U and Th in Roman lead, which was raised from the sea bottom, were lower than the limits of detection. It sounds unbelievable, nevertheless, the antique lead manufactured by Romans can indeed serve as a high-purity low-background material for the construction of Pb shields. Apart from the analysis of antique lead, the proposed approach can be easily extended to the determination of ultra trace impurities in different materials due to a very wide variety of two-phase extraction systems, which can be used in countercurrent chromatography.

Analysis of metal ion impurity in tetraethyl orthosilicate by sector field inductively coupled plasma mass spectrometry

A sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) method was developed to directly analyze metal ion impurity in tetraethyl orthosilicate (TEOS). As trace metal ion impurity in TEOS can cause a damaging effect on wafer-product-based electronic devices, it is necessary to develop an efficient analytical method for quantifying the trace metal ions in TEOS for semiconductor manufacturing. The low metal ion content (nanogram per liter level) in a TEOS solution is difficult to be analyzed directly by SF-ICP-MS. Pretreatment such as acidic digestion and direct dilution results in lower concentrations of the metal ions down to picogram per liter level which reaches the instrumental limitation and is not suitable for analysis. In this study, simple liquid–liquid extraction (LLE) was applied by adding isopropanol and deionized water to extract the metal ion in TEOS. The interfering compounds can be directly separated from the analyte by SF-ICP-MS with an appropriate resolution, thereby preventing any ambiguity in the identification of metal ions. The maximum concentration factor was 18.94. The applicability of the proposed method has also been validated by the analysis of three TEOS samples for different applications. The concentrations of metal ions with the range from nanogram per liter to microgram per liter can all be determined with good precision (RSD < 9.46%) and good accuracy (spike recoveries from 94% to 113%). This study demonstrates that SF-ICP-MS with LLE pretreatment is a promising approach for analyzing metal ion impurity in TEOS.

Heavy Metal Contamination and Ecological Risk Assessment in Soils and Sediments of an Industrial Area in Southwestern Nigeria.

Background.Increased growth of industrial activities, especially in urban centers, is one of the main sources of toxic substances in Nigeria. The level of these impacts is not well known. Soil and sediment samples from one such industrial area were examined for their mineralogical composition and heavy metals contents in order to assess the level of contamination and potential ecological risk status.Methods.Mineralogical composition of the media and their heavy metals concentrations were determined using X-ray diffractometry and inductively coupled plasma-mass spectrometry methods, respectively. Ecological risk assessment was carried out using single (contamination factor, geo-accumulation index, enrichment factor) and multi-elemental (contamination degree, pollution index and modified pollution index) standard indices.Results.The average heavy metal concentrations in soils and sediments followed the order magnesium (Mn) > chromium (Cr) > lead (Pb) > copper (Cu) > cadmium (Cd) > cobalt (Co) > nickel (Ni), with corresponding values for soils and sediments of 324.3, 79.9, 66.1, 40.7, 14.3, 9.1, 6.8 mg kg−1 and 266.8, 78.6, 40.6, 39.8, 12.9, 8.4, 4.6 mg kg−1, respectively. Principal component (PC) analysis of the results indicated three main sources of metals (industrial, vehicular activities and geogenic input). Evaluated contamination factor (Cf), enrichment factor (Ef) and geo-accumulation index (Igeo) revealed very high contamination for Pb, Cd and Cu in all of the samples, with calculated pollution index (PI) and modified pollution index (MPI) revealing that all the samples were severely polluted. Calculated potential ecological risk factor (ERi) within the industrial area demonstrated a strong potential ecological risk for Cd, Pb and Cu.Conclusions.Activities in the industrial area have affected the quality of the analyzed environmental media, with possible detrimental health consequences. Regular environmental monitoring of the industrial area and the formulation of appropriate policies that support reduction of contamination are strongly recommended. However, due to the limitations of comparing site samples with a single control sample in this work, further study is recommended to compliment this preliminary study.Competing Interests.The authors declare no competing financial interests

Validation of a simple inductively coupled plasma mass spectrometry method for detecting urine and serum iodine and evaluation of iodine status of pregnant women in Beijing

Rapid and simple method for serum and urine iodine is necessary for iodine-related diseases. This study aimed to establish and validate a simple and rapid method for quantification of iodine in human urine and serum using inductively coupled plasma mass spectrometry (ICP-MS). Generally, samples were diluted using water with 1.5% isopropanol and 7 mmol hydrous ammonium before analysis by the ICP-MS. Performance of the method was validated, and the urine and serum iodine levels of 72 pregnant women were analyzed. Results showed that the lower limit of detection of the ICP-MS method was 0.87 µg/L. No significant memory effects were observed. Recovery in both serum and urine was approximately 100%. Compared with NIST SRM3668, bias was <1%, exhibiting good accuracy. The inter-run coefficients of variation (CVs) for serum and urine iodine were 2.8–3.5% and 3.5–6.7%, respectively, and total CVs for serum and urine iodine were 3.2–3.7% and 3.9–6.7%, respectively. Comparison of the iodine results obtained by the ICP-MS method and the conventional S–K method revealed excellent correlation (r = 0.984, mean bias = –1.7%). The median urine iodine of pregnant women (125.5 μg/L) was lower than that of WHO criteria for iodine deficiency (median urinary iodine <150 μg/L) while 55.6% of the individuals with urine iodine level less than 150 μg/L. The median serum iodine level of the pregnant women was 69.0 μg/L. In conclusion, a rapid and simple ICP-MS method for urine and serum iodine measurements has been established and validated, and the pregnant women in Beijing may still suffer from insufficient iodine intake.AbbreviationsCVcoefficients of variationHPLChigh-performance liquid chromatographyICP-MSinductively coupled plasma mass spectrometryKEDkinetic energy discriminationKIpotassium iodideLODlimit of detectionS–KSandell–Kolthoff reactionPUMCHPeking Union Medical College Hospital

Modified magnetic nanoparticles by PEG-400-immobilized Ag nanoparticles (Fe3O4@PEG-Ag) as a core/shell nanocomposite and evaluation of its antimicrobial activity.

BackgroundNoble metal nanoparticles, due to their good physicochemical properties, have been exploited in biological applications. Among these metals, nanosilver has attracted great attention because of its optical properties and broad-spectrum antimicrobial activities with no drug tolerance.PurposeThe present study has attempted to conduct chemical synthesis of Fe3O4@PEG-Ag core/shell nanocomposites in aqueous solutions through co-precipitation of Fe3+ and Fe2+ ions, encapsulating the iron oxide core by poly (ethylene-glycol) (PEG) improve its hydrophilicity and biocompatibility, and immobilizing silver ions by application of NaBH4 as a reducing agent.Patients and methodsThe synthesized structures were characterized by Fourier-transform infrared (FT-IR), field emission scanning electron microscopy, energy-dispersive X-ray spectrum, wavelength-dispersive X-ray, vibrating sample magnetometer, inductively coupled plasma-mass spectrometry and transmission electron microscopy methods. Antimicrobial activity of the nanostructures against Staphylococcus aureus, Escherichia coli and Candida albicans was evaluated by broth microdilution based on the methods suggested by Clinical Laboratory Standard Institute. Furthermore, the nanocomposite was tested for possible anti-parasitic effects against Leishmania major promastigotes by MTT assay. Also, its impacts on bacterial cell morphology were defined using atomic force microscopy. Moreover, toxicity of the nanostructure related to animal cell line was determined based on MTT assay.ResultsIn general, the synthesized core/shell nanostructure can demonstrate noticeable activity against the evaluated representative microorganisms while its toxicity against animal cell line is not considerable.ConclusionThis nanostructure can be applied as a smart drug delivery system with the help of an external magnetic field or it can be used as a powerful antibiotic agent along with other antibiotics that can form a shell on its structure.

ETS1 is associated with cisplatin resistance through IKK\u03b1/NF-\u03baB pathway in cell line MDA-MB-231

BackgroundPlatinum-based drugs are used extensively in neoadjuvant chemotherapy for triple-negative breast cancer (TNBC), but their use can be limited by resistance. In this study, we established cisplatin (DDP) resistant TNBC cells to investigate the potential relationship among ETS1, IKKα/NF-κB and resistance.MethodsThe sensitivity was evaluated by MTT, apoptosis analysis. The intracellular DDP concentration difference was tested by inductively coupled plasma mass spectrometry (ICP-MS) method. Molecular pathological mechanism of DDP resistance was explored by microarray analysis and PPI network analysis. The ETS1, NF-κB signaling change were assessed by western blot and q-PCR in vitro and vivo. The existing binds between ETS1 and the core IKKα promoter were found by luciferase assay and chromatin immunoprecipitation technique (ChIP).ResultsMDA-MB-231/DDP (231/DDP) cell had a higher IC50 value of cisplatin, lower intracellular DDP concentration, and lower apoptosis ratio than MDA-MB-231 (231/wt) cell line treated with DDP. Increased ABC transporters were induced by the activation of NF-κB pathway in 231/DDP cells. ETS1, RPL6, RBBP8, BIRC2, PIK3A and RARS were six important genes for DDP-resistance based on PPI network and expression validation. Protein expression of ETS1 and IKKα were significantly up-regulated in 231/DDP cells. However, inhibition of ETS1 expression enhances chemo-sensitivity to DDP and reversed the activation of NF-κB pathway in 231/DDP cells and subcutaneous transplantation tumor in vivo. Moreover, there is existing binds between ETS1 and the core IKKα promoter though luciferase assay and ChIP.ConclusionThis study enables us to understand the functions of ETS1 in TNBC chemotherapy and suggests that ETS1 could be used as a novel marker of poor response to DDP and a potential therapeutic target for TNBC chemotherapy.

Determination of arsenic species in mainstream cigarette smoke based on inductively coupled plasma mass spectrometry

In this work, arsenic species in mainstream cigarette smoke condensates was systemically studied with inductively coupled plasma mass spectrometry. A single particle inductively coupled plasma mass spectrometry was utilized for analysis of the physical forms of arsenic, and no particle arsenic was observed in mainstream cigarette smoke condensates. The solvent extraction experiments proved that the water-soluble arsenic was the main species in mainstream cigarette smoke condensates, which was consistent with the result of single particle inductively coupled plasma mass spectrometry. Furthermore, speciation of arsenite, arsenate, monomethylarsonic acid, and dimethylarsinic acid was investigated using high performance weak anion exchange chromatography coupled with inductively coupled plasma mass spectrometry detection. The developed high performance liquid chromatography coupled inductively coupled plasma mass spectrometry method was successfully applied to the determination of arsenic species in mainstream cigarette smoke condensates with satisfactory recoveries. Four arsenic species were detected in the mainstream cigarette smoke condensates from four brands of commercial available cigarettes, and there was a great difference between the arsenic content and composition among the different brands of cigarettes. It is found that arsenate was the main species in all tested cigarette samples.

Analysis of ketone-based neurosteroids by reactive low-temperature plasma mass spectrometry.

Neurosteroids are important signalling molecules that modulate neuronal activity. Their low concentrations and low volatility make neurosteroid detection and quantification by ambient mass spectrometry challenging. Here we develop a reactive low-temperature plasma mass spectrometry (LTP-MS) method and demonstrate its potential for fast screening and quantification of neurosteroids in mouse brain. Ketone-based neurosteroids were analysed with the LTP-MS method. The plasma of the LTP was heated in order to improve the desorption efficiency of low-volatility neurosteroids. Methylamine with a concentration of 500 ppbv was employed as the reactive reagent. Neurosteroids in mouse brain tissue extracts were detected in 70s with mass errors less than ±3ppm due to coupling of the ion source with a high-performance mass spectrometer. Reaction between neurosteroids and methylamine, seeded into the LTP gas stream, resulted in the formation of protonated methylamine-neurosteroid adducts with 5- to 100-fold abundances, compared to [M+H]+ ions detected in non-reactive LTP-MS. The lowest detectable concentrations of neurosteroid standards were in the range of ng/mL. Concentrations of neurosteroids in male and female mouse brain extracts as determined with reactive LTP-MS were on the level of ng/g, comparable to results obtained with high-performance liquid chromatography-tandem mass spectrometry. The developed reactive LTP-MS is capable of providing sensitive identification and quantification of ketone-based neurosteroids in mouse brain extracts with minimal sample treatment, and showcases the potential of reactive LTP-MS as a tool for fast screening of neurosteroid levels in brain.

Biomarkers of selenium status and antioxidant effect in workers occupationally exposed to mercury

The present observation based research was designed to evaluate the influence of occupational human exposure to metallic mercury (Hg°) vapor on the biomarkers of selenium status involved in the antioxidant defense system. For this purpose we determined Hg and selenium (Se) concentrations in body fluids, the markers of antioxidant effect measured as an activity of Se-dependent enzymes (red blood cell and plasma glutathione peroxidase: GPx1-RBC and GPx3-P), concentration of selenoprotein P in the plasma (SeP-P) and total antioxidant activity in the plasma (TAA-P) in 131 male workers from a chloralkali plant exposed to Hg° and 67 non-exposed males (control group). The mRNA expression levels of glutathione peroxidases (GPX1, GPX3), selenoprotein P (SEPP1), thioredoxin reductase 1 (TRXR1), thioredoxin 1 (TRX1), peroxiredoxins (PRDX1, PRDX2) were also examined in the leukocytes of peripheral blood. Hg concentration in the blood (Hg-B) and urine (Hg-U) samples was determined using the thermal decomposition amalgamation/atomic absorption spectrometry (TDA-AAS) method and Se concentrations in plasma (Se-P) and urine (Se-U) using the inductively coupled plasma mass spectrometry (ICP-MS) method. Activities of GPx1-RBC, GPx3-P and TAA-P were determined using the kinetic and spectrophotometric method, respectively. Gene expression analysis was performed using the quantitative Real-Time PCR.The results showed significant higher Hg levels among the Hg°–exposed workers in comparison to control group (12-times higher median for Hg-B and almost 74-times higher median for Hg-U concentration in chloralkali workers). Se-P was also significantly higher (Me (median): 82.85 μg/L (IQR (interquartile range) 72.03–90.28 μg/L) for chloralkali workers vs. Me: 72.74 μg/L (IQR 66.25-80.14 μg/L) for control group; p = 0.0001) but interestingly correlated inversely with Hg-U in chloralkali workers suggesting depletion of the Se protection among the workers with the highest Hg-U concentration. The mRNA level for GPX1, PRXD1 were markedly but significantly higher in the workers compared to the control group. Moreover, concentrations of Hg-B and Hg-U among the workers were significantly positively correlated with the levels of selenoprotein P at both the mRNA and selenoprotein levels. In the multivariate model, after adjusting to cofounders (dental amalgam fillings, age, BMI, job seniority time, smoking), we confirmed that Hg-U concentration was inversely correlated with genes expression of TRXR1.This is the first comprehensive assessment of the impact of occupational exposure of workers to Hg° at both the mRNA and selenoprotein levels, with investigation of fish intake obtained by means of a questionnaire. These findings suggest that exposure to Hg° alters gene expression of the antioxidant enzymes and the level of Se-containing selenoproteins.

Ultrasound assisted fabrication of a novel optode base on a triazine based Schiff base immobilized on TEOS for copper detection

This work introduces novel selective and sensitive optical sensor based on a nano sized triazine based Schiff base (H2L) immbolized on a transparent glass substrate through the sol–gel process to detection of copper (II) ions in aqueous solutions. This sensor can determine the copper (II) in the range of 8.54 × 10−8–1.0 × 10−5 mol L−1 with a low detection limit of 1.53 × 10−8 mol L−1. The optimized geometry of H2L and its copper complex was obtained based on DFT/B3LYP levels of theory with B3LYP/6-311 + G(d,p) and LANL2DZ/6-311 + G(d,p) basis sets respectively. The calculated electronic properties of them including the molecular orbital, Mulliken population analysis, contour of electrostatic potential, and molecular electrostatic potential map confirmed the behavior of the sensor. Some advantage of the fabricated sensor such as high selectivity, sensitivity, short response time, easy production, fast regeneration, low cost, being portable and user friendly can make it a good choice to detection of Cu(II) ion in various application. The suggested sensor was revealed excellent sensitivity in the natural samples that confirmed by Inductively Coupled Plasma-Mass (ICP) spectrometry method.