2020, 41(4):141-147. DOI: 10.46770/AS.2020.04.001
Abstract:In this work, laser ionization mass spectrometry (LIMS) was developed in the laboratory and used to analyze geochemical standard reference soil samples to demonstrate the rapid analytical capability of this technique. With the help of high laser irradiance and low-pressure buffer gas, sufficient atomization and quite uniform ionization can be achieved. Little spectral interference appeared in the spectra produced by LIMS, while the signal intensity is fairly proportional to the element concentration. These features enable LIMS to acquire semi-quantitative analysis without reference materials. To further improve the quantitative accuracy, correction factors can be obtained using reference materials, while these correction factors can virtually be applied for elemental quantitation of all soil samples. The results show that LIMS is a reliable technology for the rapid analysis of metallic and non-metallic elements in soil samples.
2020, 41(4):148-153. DOI: 10.46770/AS.2020.04.002
Abstract:A high-precision MIC-ID-TIMS (multiple ion counting-isotope dilution-thermal ionization mass spectrometry) Pb isotope ratio measurement method (using 205Pb as spike) with a TRITON Plus TIMS, which is equipped with a 205Pb-Pb MIC array, using a two-line multi-dynamic data collection method, was thoroughly re-set and re-evaluated, based on our previous work.1 After some vital modifications, better than 0.01% RSE internal precision on 207Pb/206Pb for a 205Pb-spiked NIST981 with ~ 50 pg of Pb load was achieved with a measurement time of about 100 min. This is more precise compared to the traditional isotopic measurement method for the 205Pb-spiked Pb, using a single secondary electron multiplier (SEM) with five peak jumps, provided with similar ion beam intensities and measurement time. The external precision on 207Pb/206Pb was better than 0.1% (2RSD, n = 24), which is much better than that achieved by the static MIC method as previously reported1, 2. The present work indicates that the 205Pb-Pb MIC array of the TRITON Plus TIMS can be successfully used for zircon ID-TIMS U-Pb dating with high precision, particularly is useful for samples containing extremely small amounts of Pb (down to several pico-grams).
2020, 41(4):154-161. DOI: 10.46770/AS.2020.04.003
Abstract:The performance characteristics of the use of a guard electrode in laser ablation–sector field–inductively coupled plasma–mass spectrometry for multiple element quantification were investigated in this study. The guard electrode (GE) shapes and increases the ion density of the plasma prior to injection into the sample cone. The results illustrate that the GE shifts the ionization zone back to the sample cone which requires a larger carrier gas flow rate for compensation. The signal intensity of 55 elements was enhanced by a factor of 3–20 with the use of GE (hereafter denoted “GE-on mode”) compared to that without using GE (hereafter denoted “GE-off mode”), however, at the cost of higher oxide and doubly charged ion yields. The enhancement capability was negatively correlated with elemental mass number. Elements with low mass number showed a large sensitivity improvement. The limits of detections were not improved in the GE-on mode due to the enhanced background intensity. Ion transmission efficiency was improved by a factor of 3–20 and the linear relationship between mass number and transmission efficiency in GE-off mode is changed to the quadratic relationship in GE-on mode. Mass discrimination may be limited to lower mass elements with no further increase at >100 a.m.u. The ion profile in ICP illustrated that the GE increases the ion density of the plasma, which is probably related to the reduced ion kinetic energy distribution. The analyses of seven MPI-DING and one USGS glass reference materials show that the analytical precision in the GE-on mode is improved by a factor of 2–4 in comparison to the GE-off mode, and accuracy is almost identical in both modes.
2020, 41(4):162-168. DOI: 10.46770/AS.2020.04.004
Abstract:An attempt was made to determine the major, minor and trace levels of common metallic constituents in sillimanite minerals. Direct current arc atomic emission spectrometry (D. C. Arc AES) and energy dispersive X-ray fluorescence spectrometry (EDXRF) were used for the comparative evaluation. Al and Si were found to be present as major matrix elements, whereas Na, Pb, Tb, Mn, V, Ti, Ca, Mo, Ba, Y, Ni and Nb were present in the range of 20-900 μg g-1. The methodologies were developed by using standards made with a mixture of SiO2 and Al2O3 in (1:1) concentration. Multipoint standardization was carried out to establish the calibration curves for each analyte. The methodologies were validated using synthetic samples. The statistical t-test was performed in order to understand the reliability of the data obtained by EDXRF and D. C. Arc AES with a 95 % confidence limit and 8 degrees of freedom. The F- test was also performed to understand the variance of the measurements.
2020, 41(4):169-174. DOI: 10.46770/AS.2020.04.005
Abstract:In this work, fibrous TiO2@g-C3N4 nanocomposites (FTGCNCs) were used for dispersive micro-solid phase extraction of Co and Ni prior to their determination by inductively coupled plasma mass spectrometry. As a new adsorbent, the surface on FTGCNCs have rich functional groups such as –NH2, –NH– and =N–, which can selectively adsorb target ions. The adsorption behaviors of Co and Ni on FTGCNCs were investigated. The results indicated that the analytes were quantitatively retained on FTGCNCs in the pH range of 5.0-8.0 and eluted completely with 1.0 mL of 0.5 mol L-1 HNO3 solution. The main factors influencing the preconcentration and determination of the analytes were investigated in detail, including the pH of the sample solution, dosage of adsorbent, extraction/elution time, elution parameters and sample volumes. Under the optimum conditions, the detection limits of this method were 0.12 pg mL-1 and 1.34 pg mL-1 for Co and Ni, respectively. The relative standard deviations were 3.9% for Co and 4.8% for Ni (n=9, c=1.0 ng mL-1). This method was used for the determination of trace/ultra-trace Co and Ni in environmental water samples with satisfactory results. In order to verify this method, three certified reference materials of stream sediment, human hair and mussel were analyzed using the proposed method, and the determined results were in agreement with the certified values.
2020, 41(4):175-180. DOI: 10.46770/AS.2020.04.006
Abstract:Doxorubicin (DXR) is one of the commonly used chemotherapeutic agents, which is highly toxic and causes gastrointestinal and cardiac toxicity. Curcumin is used as a spice and coloring agent in food, but also possesses anti-proliferating, potent antioxidant, antitumor-promoting and anti-carcinogenic properties in vitro and in vivo. In this study, the change in element concentrations in the tissues of healthy animals was examined by administering doxorubicin and curcumin separately, or both at the same time. For this purpose, 35 wistar albino male rats were selected and randomly divided into five groups of seven each. The objective of this study was to assess and compare the levels of copper, iron, zinc and selenium in the liver, kidney, heart, and testis of the control group and in the doxorubicin-induced tissues. According to the results, the Cu, Fe, Zn, Se amounts and the Cu/Fe, Cu/Zn, and Cu/Se ratios were present at different levels in each of the five groups. In terms of element concentration, the most affected tissue by doxorubicin application is the heart, and the least affected is the kidney. The ratios of Cu/Fe and Cu/Se in the liver and the heart were highest in Group II and Group III, respectively.