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The special topography of karst areas allows organochlorine pesticides (OCPs) from the surface environment to easily infiltrate the underground environment, posing a threat to groundwater security. Methods In this study, a gas chromatography-electron capture detector (GC-ECD) was used to detect two typical OCPs, namely, HCHs and DDTs, in the Yuquandong spring system in Zigui, Hubei. Objective This study investigated spatial and temporal distribution characteristics, sources and transport of HCHs and DDTs. Results The results showed that the mass concentrations of HCHs in the water ranged from 0.09 to 5.17 ng/L, and the mass fractions of HCHs in the soils and spring sedimentsranged from 0.36 to 3.67, 0.11 to 2.53 ng/g, respectively, mass concentrations of DDTs in the water ranged from 0.13 to 7.16 ng/L, and the mass fractions of DDTs in the soils and spring sedimentsranged from 0.22 to 19.13, 0.73 to 11.53 ng/g, indicating that the pollution was dominated by DDTs. The highest mass concentrations of HCHs and DDTs in water were observed in winter; the highest mass fractions of HCHs and DDTs in the soils were observed in summer and winter, respectively; and the mass fractions of HCHs and DDTs in the spring sediments peaked in summer and spring, respectively. Characteristic ratios showed that HCHs in water, soils and spring sediments mainly originated from lindane usage, DDTs in water mainly originated from historical residues, and DDTs in the soils and spring sediments mainly originated from recent usage. Correlation analysis indicated that HCHs and DDTs could be transported from the surface water and the soils in the recharge area to the spring water and spring sediments in the discharge area, respectively. The rapid transport of HCHs and DDTs across multiple media confirmed groundwater vulnerability in karst areas. Conclusion The study can provide a reference for the protection of karst groundwater resources and the environment.

Hainan Island is the main planting base of tropical plants in China.Evaluating the level of soil pollution in this area has a great significance.In this study, we assessed the contamination levels, sources and ecological risk of 16 priority polycyclic aromatic hydrocarbons (PAHs) in agricultural soils of northern Hainan Island.A total of 100 surface soil samples were collected from plantations (coffee, banana, yam, sugarcane, orange, passion fruit and guava) and analyzed for PAHs concentration using gas chromatography equipped with a mass spectrometry detector (GC-MS).The average of ∑16PAHs from plantation soil was 37.6 ng/g, which was below the background of national soil and the no pollution limit of 200 ng/g determined by Netherlands.Three-, four- and five-ring PAHs were dominant components, accounting for 25.8%, 26.8% and 23.5% of the total PAHs, respectively.Source analysis suggested that PAHs of soil in these plantations were mainly derived from the exhaust gas of locomotives and partially from oil spill as well as low temperature combustion of coal and biomass.In ecological risk assessment, the benzo(a) pyrene equivalent concentration (∑16BaPeq) presented a much lower level than the guideline values announced by Chinese Environmental Protection Agency, demonstrating that the PAHs contamination level in solis was acceptable.

Serious environmental problems occurred on the coast of the Shandong peninsula, particularly pollution from polycyclic aromatic hydrocarbons (PAHs). The distribution, sources and ecological risk assessment of 16 PAHs in 62 sites of surface sediments from the Shandong coast have been investigated. Results show that the total concentrations of 16 PAHs in surface sediments from the coastal zones range from 0.06 to 3191.40 ng/g with an average of 262.08 ng/g. Except for a few sites, the concentration of PAHs was relatively lower than that in other areas around the world. The PAHs of the study area originated from mixed petroleum leakage, oil combustion, incomplete combustion of carbon, wood and fossil fuels indicated by the selected ratios of PAHs, the two-tailed Pearson correlation analysis and principal components analysis. The ecological risk assessed by the effects range-low (ERL) and the effects range-median (ERM) indicates little negative effect from surface sediments on the coast of the Shandong peninsula. However, acenaphthene and fluorenein in the sites of Laizhou Bay, Weihai and the Qingdao coast may pose a potential risk to the environment. In conclusion, the negative effects of 16 PAHs in the surface sediments from the Shandong peninsula were weak and easily controlled.

Due to the low concentrations of cadmium and tin in lead alloys and the single element analysis performed by using the national standard method, the analytical protocol is very complex and the detection limit is not ideal. In this paper, a new analytical method for determining trace cadmium and tin in lead alloys by Inductively Coupled Plasma-Mass Spectrometry is reported. In this method, lead alloys are digested by low-concentration of nitric acid. The low temperature and slow digestion process assures the complete dissolution of samples and reduces the mass spectrometry interferences from multiple ions. Lead matrix matching and the addition of tartrate assure the medium consistency of the standard and sample and avoid hydrolysis of the tin content. Using 103Rh as an internal standard and 111Cd and 118Sn as the measuring isotopes, the mass spectrometry interferences are reduced. The detection limits of Cd and Sn are 0.05 ng/g and 0.04 ng/g, respectively, which are much lower than those of the national standard method (1-6 μg/g). The precision of this method is 4.0%. This method needs a relatively small sample weight, which simplifies the analytical process and can determine trace elements in alloys precisely and accurately.

In order to evaluate the agricultural ecological environment risk caused by industrialization over a long period of time, the distribution characteristics of 22 organochlorine pesticide residues in the soils under different land use forms from four perpendicular profiles were analyzed using gas chromatography.Research results indicate that the mean concentrations of OCPs were in the order:vegetable land in industrial park(139.87 ng/g)> waste land in industrial park(103.1 ng/g)> vegetable land in agricultural areas(26.27 ng/g)> paddy field in agricultural areas(2.50 ng/g).DDTs and HCHs were still the primary pollutants of OCPs in the topsoils with DDTs concentrations of 0.14-485.73 ng/g(mean 44.43 ng/g) and HCHs concentrations of 0.69-66.69 ng/g(mean 7.73 ng/g).The ratio of(DDD+DDE)/DDTs indicated that there was almost no new input of pollution in this area.The concentrations of DDTs and HCHs tend to decrease gradually with the increase in the depth of soil profile.This trend is related to the fact that the rock types of zone of aeration in profile soil are mainly clays and sub-clays, which reduce the vertical transfer dynamics of organochlorine pesticides induced by the overland runoff.This study provides some references to the control and improvement of pollution conditions in the region.

At present, little research on perfluorinated compounds (PFCs) has been carried out in rural areas. To better determine the pollution level and the geographical distribution of PFC in rural areas, soils, surface waters, and groundwaters were collected from 8 rural areas in eastern China. Seventeen PFC compounds were analyzed using Solid Phase Extraction (SPE) and LC-MS-MS. The sources of PFCs are determined by compound ratios. Results show that PFOA (0.34-14.5 ng/g) is the dominant perfluorinated carboxylic acids (PFCAs) and PFOS (0.02-0.08 ng/g) is the dominant perfluoroalkane sulfonates (PFSAs) in the soils. PFCs in surface water are mainly PFOA (4.8-29.6 ng/L), PFHxA (0.73-31.8 ng/L), PFOS (nd-7.1 ng/L), and PFBA (nd-6.1 ng/L). PFOA (nd-176 ng/L), PFHxA (nd-50.1 ng/L), and PFBA (0.08-16.1 ng/L) are the dominant PFCs in groundwater. PFCs in soil and groundwater decrease from south to north. Two main sources of PFCs are domestic sewer and atmospheric precipitations, of which atmospheric precipitations have a greater contribution.

Determination of low-level gold in geochemical samples by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) has good accuracy. However, this method is limited to the determination of trace gold in plants due to the large sample amount of > 20 g required, incomplete ashing in the muffle furnace, and a high detection limit of 0.29 ng/g. A revised method of determining trace gold in plant samples from a gold mining area by GFAAS is proposed. The heating process in a graphite furnace Involves ashing and atomization temperatures of 1000℃ and 2000℃, respectively, and ascorbic acid is used as the matrix modifier. Sample ashing temperature of 500℃ and an ashing time of 2.0 h in a porcelain crucible can guarantee the complete ashing of samples and avoid volatilization loss. This method uses small weight samples of 5.0g, the detection limit is 0.03 ng/g, the precision is 6.8%-11.9%, and standard addition recoveries are 83.8%-104.7%. It was also found that different plants have different capacities of gold enrichment with maize containing the highest enrichment.

For the research on degradation and remediation of soil polycyclic aromatic hydrocarbons (PAHs) pollutants, researchers have been trying to find an effective method to quantize the dynamic processes. Many approaches have been designed, such as spiked experiment, concentrations comparison before and after the degradation, and modeling calculations. However, all of this culminates in contradictory results and lack of corroboration of the actual environment. Compound Specific Isotope Analysis (CSIA) technique is used in this study to investigate the phytodegradation process of soil PAHs with maize as the testing plant. Total concentrations of 16 PAHs in the bulk soil, rhizosphere soil and in the controlled soil samples were (299.8±37.9) ng/g, (272.2±11.6) ng/g, and (281.5±34.7) ng/g, respectively, all much lower than the original cultivating soil (380.8 ng/g). The soil PAHs concentrations did not show significant decline tendency during the maize growing period, except for 3-ring PAH compounds which was consistent with the accumulation effect of the 3-ring PAHs in maize roots and leaves. The δ13C value of 6 PAH compounds ranged from -34.31‰ to -23.95‰ with fluctuations between -0.6‰--9.0‰, and all δ13C values turned lighter with maize plants growing except that of Pyrene. No significant correlation between δ13C and the concentration of 4-, 5-ring PAHs was observed during the maize cultivating process. Most research indicates that PAHs and other macromolecular compounds strongly resist phytodegradation, which illustrates less obvious carbon isotope fractionation. PAH compounds below 3 rings would degrade more easily and the isotopes fractionate more significantly than those of other macromolecular compounds, thus maing the technique of CSIA more advantageous for understanding the transportation pathway of these compounds.

For the research on degradation and remediation of soil polycyclic aromatic hydrocarbons (PAHs) pollutants, researchers have been trying to find an effective method to quantize the dynamic processes. Many approaches have been designed, such as spiked experiment, concentrations comparison before and after the degradation, and modeling calculations. However, all of this culminates in contradictory results and lack of corroboration of the actual environment. Compound Specific Isotope Analysis (CSIA) technique is used in this study to investigate the phytodegradation process of soil PAHs with maize as the testing plant. Total concentrations of 16 PAHs in the bulk soil, rhizosphere soil and in the controlled soil samples were (299.8±37.9) ng/g, (272.2±11.6) ng/g, and (281.5±34.7) ng/g, respectively, all much lower than the original cultivating soil (380.8 ng/g). The soil PAHs concentrations did not show significant decline tendency during the maize growing period, except for 3-ring PAH compounds which was consistent with the accumulation effect of the 3-ring PAHs in maize roots and leaves. The δ13C value of 6 PAH compounds ranged from -34.31‰ to -23.95‰ with fluctuations between -0.6‰--9.0‰, and all δ13C values turned lighter with maize plants growing except that of Pyrene. No significant correlation between δ13C and the concentration of 4-, 5-ring PAHs was observed during the maize cultivating process. Most research indicates that PAHs and other macromolecular compounds strongly resist phytodegradation, which illustrates less obvious carbon isotope fractionation. PAH compounds below 3 rings would degrade more easily and the isotopes fractionate more significantly than those of other macromolecular compounds, thus maing the technique of CSIA more advantageous for understanding the transportation pathway of these compounds.

Fluorescence spectrometry, with the characteristics of high sensitivity, low detection limits and rapid analysis, avoids complex separating work in the chromatography method, and is suitable for oil and gas geochemical exploration samples requiring a large number of assays. In this paper, sample pretreatment methods and analytical conditions that were optimized in order to analyse aromatic hydrocarbons in oil samples by fluorescence spectrometry are reported. Ultra pesticide residue grade n-hexane was selected as the extraction solvent, which simplified the purification operation, and intermittent oscillation was selected to improve the extraction effect of aromatics. Through selecting proper standard materials (naphthalene, phenanthrene and chrysene) and adopting an external standard method, aromatic hydrocarbon in the samples was determined under the optimal analytical conditions. With the excitation wavelength of 265 nm and the emission wavelength of 320 nm, 360 nm and 405 nm, the fluorescent spectra of aromatic hydrocarbon were studied. The relative intensities were converted into the concentration of a certain standard material, which could then be used to compare the fluorescence data between different laboratories and different instruments. The detection limit of the method was 1.8 ng/g (naphthalene), which was lower than the limit of the national industry standard (2.0 ng/g, SY/T 6009.8—2003). The precision results of the method (RSD, n=12) were 4.5% (320 nm), 9.6% (360 nm) and 14.7% (405 nm), respectively. Through improving the quality control and management, the proposed method has been conducted successfully in the Daqin oil field, and it was found that the fluorescent data could effectively indicate sampling depth and anomalies.

Fluorescence spectrometry, with the characteristics of high sensitivity, low detection limits and rapid analysis, avoids complex separating work in the chromatography method, and is suitable for oil and gas geochemical exploration samples requiring a large number of assays. In this paper, sample pretreatment methods and analytical conditions that were optimized in order to analyse aromatic hydrocarbons in oil samples by fluorescence spectrometry are reported. Ultra pesticide residue grade n-hexane was selected as the extraction solvent, which simplified the purification operation, and intermittent oscillation was selected to improve the extraction effect of aromatics. Through selecting proper standard materials (naphthalene, phenanthrene and chrysene) and adopting an external standard method, aromatic hydrocarbon in the samples was determined under the optimal analytical conditions. With the excitation wavelength of 265 nm and the emission wavelength of 320 nm, 360 nm and 405 nm, the fluorescent spectra of aromatic hydrocarbon were studied. The relative intensities were converted into the concentration of a certain standard material, which could then be used to compare the fluorescence data between different laboratories and different instruments. The detection limit of the method was 1.8 ng/g (naphthalene), which was lower than the limit of the national industry standard (2.0 ng/g, SY/T 6009.8—2003). The precision results of the method (RSD, n=12) were 4.5% (320 nm), 9.6% (360 nm) and 14.7% (405 nm), respectively. Through improving the quality control and management, the proposed method has been conducted successfully in the Daqin oil field, and it was found that the fluorescent data could effectively indicate sampling depth and anomalies.

The background values of chemical elements in stream sediments are an indispensable tool in geochemical prospecting work, and they are of important significance for regional geochemical anomalies assessment. However, there is a lack of poly-elements background values in Tibet, which are based on the surface material from the micro landscape area thereby limiting understanding of the existing stream sediment anomalies to a certain extent. Analysis of the chemical elements background values and distribution characteristics of 69 kinds of elements in 2800 stream sediment combination samples covering about 12000 km2 in Yangbajain-Qinglong area have been conducted and are reported in this paper. From north to south, the area is divided into three geochemical divisions of Bangor-Basu, Longer-Nanmulin and Lhasa-Zayu. The results indicate that content of SiO2 (68.6%-77.0%) in the study area is higher compared to the average value of stream sediments nationwide. The high content of SiO2 is related to strong weathering and occurrence of large-scale intermediate-acid intrusive rocks in the study area. While other elements are lower and differentiated in three geochemical divisions. Bangor-Basu division is characterized by enrichment of Li, Sr, B, N and Cl which are related to high-temperature hydrothermal or gas-liquid. Longer-Nanmulin division is enriched with iron group elements, rare element (Zr) and rare earth element (Sc). Lhasa-Zayu division is enriched with petrogenetic elements, light rare earth elements, rare elements, dispersed elements and chalcophile metallogenic elements. The differences in element content distribution are closely related with the stratum, rock mass, deposits and mineralization in the geochemical divisions. This study gives the background values for 69 kinds of elements in the Yangbajin-Qinglong area, such as the chalcophile metallogenic elements of Au, Ag, Cu, Pb and Zn with 0.26 ng/g, 41 ng/g, 4.04 μg/g, 25.2 μg/g and 25.6 μg/g, respectively. These data fill a vacancy in the chemical elements background values on the micro-landscape areas of Tibet, and provide references for regional exploration study and geological prospecting work in Yangbajain-Qinglong and adjacent areas.

There are currently three principle methods to measure trace and ultra-trace gold in geological samples, including activated carbon enrichment-Emission Spectrometry, foam enrichment-Graphite Furnace Atomic Absorption Spectrometry (GFAAS), and activated carbon enrichment-Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Of these, the Emission Spectrometry uses domestic equipment, with low cost and a lengthy process; the GFAAS is easy to operate but is costly as it employs an imported graphite tube. The ICP-MS method has a low detection limit but demands higher environmental conditions with high cost. The detection limits of these three methods are from 0.1 to 0.3 ng/g. As the composition of the ore mineral is very complicated, satisfactory results for the analysis of geological samples are provided by adopting a suitable analysis method based on the effective enrichment and separation. To ensure sensitivity and accuracy of sample requirements, selection of the analysis method should follow the specific sample and laboratory conditions. According to the signal-to-noise ratio (S/N) concept proposed by Doctor Genichi Taguchi in measurement engineering, the S/N is equal to the magnitude of the mean of the process compared to its variation. The bigger the S/N, the greater the anti-interference ability, the higher sensitivity, the better the linearity, the safer, and the more reliable is the measuring system. In this paper, a description of how the Taguchi measurement quality control method was conducted to evaluate three common analysis methods for trace and ultra-trace gold measurement in geological samples for the first time is given. The measurement data obtained by the three common methods for three national standard materials were processed to calculate the S/N values and the relative standard uncertainties, respectively. By comparing the three S/N values and the relative standard uncertainties, a more stable method was selected. The experimental results show that all three analytical methods met the requirements of the trace gold measurement in geological samples, whose Au content is greater than 1 ng/g, however, the activated carbon enrichment-ICP-MS is more suited for the ultra-trace gold in samples whose Au content is less than 1 ng/g.

The background values of chemical elements in stream sediments are an indispensable tool in geochemical prospecting work, and they are of important significance for regional geochemical anomalies assessment. However, there is a lack of poly-elements background values in Tibet, which are based on the surface material from the micro landscape area thereby limiting understanding of the existing stream sediment anomalies to a certain extent. Analysis of the chemical elements background values and distribution characteristics of 69 kinds of elements in 2800 stream sediment combination samples covering about 12000 km2 in Yangbajain-Qinglong area have been conducted and are reported in this paper. From north to south, the area is divided into three geochemical divisions of Bangor-Basu, Longer-Nanmulin and Lhasa-Zayu. The results indicate that content of SiO2 (68.6%-77.0%) in the study area is higher compared to the average value of stream sediments nationwide. The high content of SiO2 is related to strong weathering and occurrence of large-scale intermediate-acid intrusive rocks in the study area. While other elements are lower and differentiated in three geochemical divisions. Bangor-Basu division is characterized by enrichment of Li, Sr, B, N and Cl which are related to high-temperature hydrothermal or gas-liquid. Longer-Nanmulin division is enriched with iron group elements, rare element (Zr) and rare earth element (Sc). Lhasa-Zayu division is enriched with petrogenetic elements, light rare earth elements, rare elements, dispersed elements and chalcophile metallogenic elements. The differences in element content distribution are closely related with the stratum, rock mass, deposits and mineralization in the geochemical divisions. This study gives the background values for 69 kinds of elements in the Yangbajin-Qinglong area, such as the chalcophile metallogenic elements of Au, Ag, Cu, Pb and Zn with 0.26 ng/g, 41 ng/g, 4.04 μg/g, 25.2 μg/g and 25.6 μg/g, respectively. These data fill a vacancy in the chemical elements background values on the micro-landscape areas of Tibet, and provide references for regional exploration study and geological prospecting work in Yangbajain-Qinglong and adjacent areas.

There are currently three principle methods to measure trace and ultra-trace gold in geological samples, including activated carbon enrichment-Emission Spectrometry, foam enrichment-Graphite Furnace Atomic Absorption Spectrometry (GFAAS), and activated carbon enrichment-Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Of these, the Emission Spectrometry uses domestic equipment, with low cost and a lengthy process; the GFAAS is easy to operate but is costly as it employs an imported graphite tube. The ICP-MS method has a low detection limit but demands higher environmental conditions with high cost. The detection limits of these three methods are from 0.1 to 0.3 ng/g. As the composition of the ore mineral is very complicated, satisfactory results for the analysis of geological samples are provided by adopting a suitable analysis method based on the effective enrichment and separation. To ensure sensitivity and accuracy of sample requirements, selection of the analysis method should follow the specific sample and laboratory conditions. According to the signal-to-noise ratio (S/N) concept proposed by Doctor Genichi Taguchi in measurement engineering, the S/N is equal to the magnitude of the mean of the process compared to its variation. The bigger the S/N, the greater the anti-interference ability, the higher sensitivity, the better the linearity, the safer, and the more reliable is the measuring system. In this paper, a description of how the Taguchi measurement quality control method was conducted to evaluate three common analysis methods for trace and ultra-trace gold measurement in geological samples for the first time is given. The measurement data obtained by the three common methods for three national standard materials were processed to calculate the S/N values and the relative standard uncertainties, respectively. By comparing the three S/N values and the relative standard uncertainties, a more stable method was selected. The experimental results show that all three analytical methods met the requirements of the trace gold measurement in geological samples, whose Au content is greater than 1 ng/g, however, the activated carbon enrichment-ICP-MS is more suited for the ultra-trace gold in samples whose Au content is less than 1 ng/g.

In recent years, the main focus for improving detection methods for organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in groundwater, soils and sediments has focused mainly on pretreatment and analysis conditions. Comprehensive methods including sampling point design and sample collection were seldom studied. A new method was has been developed for the simultaneous determination of 22 OCPs and 8 PCBs in soils and sediments by Gas Chromatography coupled with electron capture detection. Method detection limits range from 0.09 ng/g to 0.48 ng/g, and the average recoveries are 58.7%-133.7%. This developed method seems to be a relatively integrated and widely applicable method, including sampling point design, sample collection, transportation, preservation, extraction, clean-up, concentration, determination, data analysis and reporting. Alternative technologies were recommended for extraction, clean-up and Gas Chromatographic condition, etc, which improves the flexibility of the method. The results show that the sampling point design for the samples collected from different depths should be considered on the basis of scouting samples and pre-existing data since the representativeness of samples comprehensively depends on selecting procedure, sampling point design, sample collection and preparation. A flexible Gas Chromatographic condition can be used for those samples with rare target compounds, and a corresponding Gas Chromatographic condition can be used further if special target compounds need to be separated. Sequence of the samples should not be oversimplified in order to save cost.

Extraction by foam plastics is a common method to determine platinum group elements (PGEs) for most geological samples, however, the high temperature ashing method conducted to release Au and Pt, has complex processing. According to the insoluble residues for Pt in aqua regia, produced by the high temperature ashing method, the analysis results are unstable and produce low recovery rates. The unsatisfactory duplicate results were yielded by the sole use of 20 g/L thiourea as the elution solution. In this paper, this method was improved by decomposing the samples in 50% aqua regia in a closed system, reduced by SnCl2 and concentrated by foam plastics then eluted by 20 g/L thiourea solution-20% hydrochloric acid. Au and Pt were continuously determined by Graphite Furnace Atomic Absorption Spectrometry. The adsorption efficiency was stable under the oscillation time and the absorption temperature of 30 min and 20℃, respectively. The recovery rates of Au and Pt were both greater than 95%. The detection limits of the Au and Pt were 0.23 ng/g and 0.39 ng/g with RSD of 1.8%-10.3% and 1.3%-13.3% (n=10), respectively. The method has been verified by determination of national first grade standard material with satisfactory results. The extraction of foam plastics avoided the high-temperature ashing by being extracted several times with aqua regia and one time in 100℃ water bath which greatly simplified the chemical procedure. Compared with high-temperature ashing, the extraction temperature was greatly reduced, the analysis process was simple and the number of samples was significantly increased for each batch with less interferences and low blanks. The improved method met the needs of various testing of geological samples except for the insoluble Pt minerals by aqua regia.

Determination of trace elements in minerals usually requires pre-concentration and separation with many spectral line interferences during measurement. The concentrate ores were calcined at high temperature to remove the C and S. The calcinates were then digested by using the HCl-auqa regia-HF acids system. The D290 anion exchange resin and activated charcoal procedures were conducted to enrich Pt and Pd. The contents of Pt and pd were obtained by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) with internal standard elements of Y, In and Bi and measured isotopes of 105Pd and 195Pt. The absorption property and separation conditions of D290 anion exchange resin to trace Pt and Pd in copper concentrate ores were studied. The enrichment effects of Pt and Pd were above 90%, the recoveries were 92.0% and 96.0%, and the relative standard deviations (RSD, n=6) were smaller than 4%. The detection limits of the method were 0.126 ng/g and 0.105 ng/g for Pt and Pd. The presented method mostly reduced the inferences from other ions to the target elements of Pt and Pd. Moreover, the collision reaction between the internal standard elements and high purity Ar effectively reduced the matrix effect and isobaric interference. Five random geological samples were analyzed by this method in comparison with the method of NiS fire assay ICP-MS and the established method had the advantages of simple pretreatment and high enrichment of Pt and Pd with lower detection limits.

In past decades, large amounts of organochlorine pesticides (OCPs) were produced and used in China. These abandoned OCPs manufacturer sites have become high-risk areas. Previous studies have investigated the contamination status of OCPs in these sites. However, most of the available data focused only on the inside of the factory and few studies consider the pollutions and risks of OCPs in the surrounding area. Levels and distributions of hexachlorocylohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and DDT metabolites were investigated in surface soils from an abandoned manufacturing site, in Chongqing, southwest China, in order to better understand the contamination status and environmental impact on the surrounding area. In this study, the potential human health risks were also assessed from within the factory and from the surrounding area. Concentrations of ΣHCHs ranged from 3.89 to 13385.78 ng/g in surface soils from inside the factory, which were generally lower than those reported in other contaminated sites. Levels of ΣDDTs ranged from 22.74 ng/g to 11186.10 ng/g in surface soils, which were consistent with previous observations in contaminated sites located in Zhangjiakou and Yangzhou city, but lower than those in Xingtai, Taiyuan and Qingdao city. The results of health risk assessment showed that the carcinogenic risk of OCP contaminants exceeded the acceptable risk in soils from inside the factory, which contributed to the heavily-polluted area. Within 400 meters from the manufacturing facility, the levels of OCPs in soils were also high although they were lower than those inside the factory. To children, the carcinogenic risk of HCHs and DDTs in surface soils is still higher than the standard recommended by some research institutions. With the distance increasing to the site, levels of HCHs and DDTs decreased with the trend of the power function, which indicated that the pollution of OCPs only occurred in a certain region outside the factory. Therefore, the OCP pollutions and risks should be considered from not only inside contaminated sites but also certain regions outside sites.

In Re-Os isotope chronology, the acetone extraction process is quicker and easier compared to the anion exchange method. The Re solution which was separated and purified by acetone extraction is suitable for the measurement by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), but unsuitable for Negative Thermal Ionization Mass Spectrometry (N-TIMS) directly because of high salt contents. An improvement was made to the acetone extraction method to separate and purify Re for N-TIMS determination by increasing the alkalinity concentration from 5 mol/L to 10 mol/L. Compared with the anion exchange method, the acetone extraction process is not only easier to operate with lower blank (Re 3-7 pg), but also saves time. The signal intensity of Re was over 100 mV per 1 ng Re, which met the requirements of a high-accuracy instrument measurement completely. The national first grade standard material of JDC (GBW 04436) and the laboratory reference material of JCBY were measured to verify the improved method. The Re contents of JDC and JCBY obtained from this method were (17.17±0.50) μg/g and (38.34±0.44) ng/g, respectively, which were consistent with the certified value of JDC (17.39±0.32) μg/g and the certified value of JCBY (38.61±0.86) ng/g. The improved procedure was applied to practical samples with good long-term results.

Fire assay separation enrichment technology has been applied to precious metals analysis, however, its ingredients are complex, time-consuming, analysis costs are relatively high and blank controls are more difficult. A new method was set up such as the samples were dissolved with H2O2-HCl before Pt, Pd and Au were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). In 10% hydrochloric acid solution, LSC-400 mercapto resin and activated carbon were mixed as the adsorbent. Pt，Pd and Au in the sample solution were separated and enriched by using dynamic adsorption. Lu was selected as the internal standard element to eliminate non-spectral interference and spectrum interference along with tracers of 195Pt, 197Au and 108Pd. The recovery rates of each element were more than 96.4%. The detection limits were 0.06 ng/g for Pt, 0.08 ng/g for Pd and 0.12 ng/g for Au. Compared with the detection limits, this established method was better than the fire assaying method and other separation and enrichment methods. The method has been applied to the determination of these elements in National Standard Materials for PGEs and results were in agreement with the certified values. The relative standard deviations (RSD, n=12) was less than 16.1%. The method is simple, low cost and greatly improves the speed of analysis，and effectively reduces the blanks of the chemical processing.

BACKGROUND Hydride generation-atomic fluorescence spectroscopy (HG-AFS) is highly sensitive for the determination of trace selenium in geological samples. However, the complex matrix increases the analysis difficulty, especially owing to interference caused by organic carbon, complicated complexes, and coexisting ions in samples rich in organic matter and sulfides. Therefore, sample pretreatment is important. The use of conventional thiol cotton fiber (TCF) to enrich and separate selenium often leads to unstable recovery and premature saturation of the TCF when dealing with samples rich in organic matter and sulfides. OBJECTIVES To establish a method suitable for the determination of trace selenium in geological samples rich in organic matter and sulfides. METHODS For samples rich in organic matter, a double TCF column (mTCF=0.15g) was used to carry out adsorption twice. The recovery for high-sulfur geological samples could be increased either by increasing the amount of TCF (mTCF ≤ 0.2g) or reducing the sample amount. RESULTS The measurement results for the reference materials and actual samples showed that the optimized method satisfied the analysis requirements as selenium recoveries of >95.1% and >95.5% were achieved for the organic-rich and sulfide samples, respectively. Microwave digestion can effectively avoid the loss of selenium during digestion; the measured selenium content was consistent with that reported in the literature. CONCLUSIONS The improved method is suitable for geological samples rich in organic matter and sulfides, which can be used to determine trace selenium (ng/g to μg/g levels) in geological samples.

BACKGROUND Rice is the staple food of about half of the world's population, and the dependence of Asian staple food on rice exceeds 90%. There are varying degrees of arsenic (As) pollution all over the world. As can accumulate in rice and enter the human body, causing health problems. OBJECTIVES To reveal the mechanism of As absorption in rice. METHODS The content and species characteristics of As absorbed by rice and the species analysis techniques were reviewed. The mechanisms of As absorption, tolerance and detoxification by rice were summarized. RESULTS The content of As in rice ranged from a few to several hundred ng/g. The process of As entering the rice from the soil involved complex physical and chemical changes and species transformation. Arsenic mainly existed in the form of arsenate, arsenite, thiol and methyl coordination in rice. Field water management, fertilization and soil amendments controlled the absorption of As in rice. Each technique had their advantages and disadvantages. Soil pH, redox conditions, organic matter and coexisting elements were the key factors affecting As absorption by rice. Agronomic methods can control the absorption of As by rice. Many factors such as arsenic biogeochemistry and the absorption and metabolism of arsenic in rice agroecosystems affect the concentration of arsenic in rice and grain. Comprehensive consideration of the effects of agronomic activities on soil pH, redox conditions, organic matter structure and coexisting elements, and different geographic factors such as soil characteristics and economic factors were the keys to realize the control of arsenic absorption by rice in production practice. CONCLUSIONS Comprehensive use of multiple agronomic methods for rice farming is an important way to control the absorption of arsenic in rice in the future. Application of new agronomic methods in the control of arsenic absorption by rice, the impact of climate change on arsenic absorption by rice, and application of non-destructive in situ and in vivo analysis techniques for As speciation analysis, are keys for more scientifically and effectively controlling the arsenic content in rice and reducing the risk of human As exposure on the global scale in the future. These are also the key development directions and challenges in the future.

BACKGROUND In recent years, the pollution of synthetic musk in the environment has increased. This kind of material has potential carcinogenic and environmental hormone effects and poses a threat to human health. Therefore, it has attracted increasing attention from scientists. The analytical technology of synthetic musk in environmental samples such as water and soil has developed rapidly. The concentration of synthetic musk in sediments has reached several thousand ng/g, but the methods for the simultaneous extraction and purification and rapid analysis of various types of synthetic musk in complex matrices of sediments are yet to be studied. OBJECTIVES To establish a rapid method for the analysis of 14 typical synthetic musks in sediment samples by accelerated solvent extraction (ASE) combined with gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS). METHODS Accelerated solvent extraction was used for sample preparation. The ASE cell was filled up with sorbent (0.4g GCB combined with 1.0g SAX) and 5.0g sediment samples. The sample was extracted in two cycles with mixed solvents hexane-acetone (V/V, 4:1) at 80℃. After preconcentration, the extracted solution was determined by GC-MS/MS. RESULTS The linear range of this method for fourteen target compounds ranged from 5ng/mL to 200ng/mL. The average spike-added recoveries ranged from 70.6% to 121.5%, the relative standard deviations (RSD, n=7) were 0.97%-19.5%. The recoveries of surrogates were 72.2%-116.8%. The detection limits of the method were 0.10-0.19ng/g for nitro musk, 0.09-0.14ng/g for polycyclic musk, and 0.11-1.93ng/g for macrocyclic musk. CONCLUSIONS This method can satisfy the analysis of musk in sediments with complex matrices.

BACKGROUND The geochemical exploration for gold deposits is based on the accurate determination of gold. The content of gold in geochemical samples is usually at the level of ng/g, which needs to be preconcentrated before determination by inductively coupled plasma-mass spectrometry (ICP-MS) or graphite furnace absorption spectroscopy (GFAAS). At present, the exploration of buried deposits is the frontier of geochemical exploration technology and the extraction of gold mobile fraction is one of the most effective approaches to find concealed gold deposits. Compared with whole rock gold analysis, the gold mobile fraction content is much lower, which requires specific leaching, efficient preconcentration and accurate determination. OBJECTIVES To selectively extract gold mobile fraction and find surface secondary anomaly information for exploring concealed ore bodies. METHODS Experiments were carried out on the extraction agent and determination of gold mobile fraction by ICP-MS. Ammonium citrate was used to promote the disassociation of the adsorption of exchangeable form gold from the surface of clay minerals and secondary minerals in the soil. The complexation of thiourea and sodium thiosulfate was applied to diffuse the extracted gold into the solution to achieve the purpose of selective extraction. The procedure for gold preconcentration from extraction solution and the ICP-MS determination method were established. RESULTS The experiments determined that the extractant was composed of 5g/L ammonium citrate, 2g/L thiourea, and 5g/L sodium thiosulfate. The extraction time was 24h, and the active carbon was used to preconcentrate gold in the acidic thiourea medium. The gold adsorption rates were 89.6%-109.2%, and the ashing temperature of the concentration materials were 650-700℃. The detection limit of the method was 0.05ng/g, the relative standard deviations (RSDs) ranged from 9.4% to 10.2%, and the recoveries were from 91.2% to 93.4%. CONCLUSIONS Compared with the published method, extraction with ferric sulfate-thiourea-sodium thiosulfate solution and determination by GFAAS, this method has the advantages of low detection limit, wide linear range and fast analysis. This method has been successfully applied in the geochemical exploration of gold deposits in the forest swamp landscape area of Dongan, Heilongjiang Province. Gold anomaly delineated is consistent with the location of the concealed gold deposit.

BACKGROUND The accurate determination of ionic phase rare earths in ion-adsorption rare earths is of great significance for the evaluation of rare earth ore bodies. Ionic phase rare earths are adsorbed on clay minerals in the form of hydroxyl or hydrated hydroxyls and can be exchanged and desorbed with strong electrolytes (Mg2+, NH4+, etc.) into solution. The former used ammonium sulfate as the leachate to achieve the desorption and extraction of rare earth ions in the ion phase, but the solution concentration, leaching process and other aspects of choice, leaching rates (60% to 90%) are different. There is no efficient and uniform leaching method conducive to the accurate determination of ionic phase rare earth elements. OBJECTIVES To establish a high-efficiency leaching process by ammonium sulfate solution and determine the accurate contents of ionic-phase rare earth elements. METHODS The leaching parameters (solid-to-liquid ratio, ammonium sulfate concentration, best sample weight, and soaking time) of rare-earth ions by ammonium sulfate were standardized through comparative experiments, which reduced the loss of ionic phase rare earth during leaching. The leaching rates were from 88% to 98%, and ICP-MS was used to accurately determine the ion phase rare earth component. RESULTS The detection limits are 0.05-5.11 ng/g, and the relative standard deviations (RSDs) are 1.80%-10.01% for volcanic rock, 1.06%-7.27% for metamorphic rock, and 1.72%-7.58% for sedimentary rock. CONCLUSIONS The analytical results of the collaborative laboratory verify the reliability and accuracy of the method. This method is easy to operate and has high analysis efficiency. It provides the base for the establishment of relevant industry standards and national standards.

Characteristics of REEs in peridotite is significant for studying petrogenesis and magmatic processes. Due to the serious interference of matrix elements such as Mg and Fe, it is difficult to determine the low contents of REEs in peridotite (∑REEs=0.1-1 μg/g) accurately. The previous method was sealed acid digestion at high pressure combined with ion-exchange which was used to separate REEs and matrix elements of Mg and Fe and preconcentrate REEs. However, due to the long digesting time (almost 7 days) and various operating steps, it is not conducive to the analysis of lots of samples. In this study, the sample was decomposed by Na2O2 alkali fusion, and coprecipitated with Mg(OH)2 and Fe(OH)3. Then, the solution was separated from precipitation by centrifuging for a rapid separation of REEs from matrix elements of Mg and Fe. Contents of REEs are determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). For this method, the detection limits of REEs range from 0.17 to 2.18 ng/g, and the recoveries are 95%-101%. This method was used to analyze the national standard reference materials GBW07101 and GBW07102. The relative error between analytical results and recommended values is less than 20%, and the relative standard deviation (RSD, n=11) is less than 10%. The method not only reduces the losses caused by stepped precipitation, but also shortens the analysis period (only one day for sample-digestion). It is simple to operate, and efficient in analysis.

Graphite has relatively high Re and Os contents and is an ideal mineral for Re-Os isotope dating. However, there are few studies on Re-Os dating of graphite. Particularly for the graphite which was formed by deformation of coal beds, the variation in Re-Os isotope system needs further study. The Lutang graphite deposit in Hunan is one of the typical cryptocrystalline graphite deposits in China. The ore-bodies are hosted in coals of the Permian Longtan Formation. In this study, the Re-Os isotopic compositions of the graphite samples from Lutang deposit and the raw coal samples from the peripheral area were analyzed by digesting sample in the Carius tube, direct distilling Os from the Carius tube, extracting Re by acetone and determining Re and Os isotopes by Negtive Thermal Ionization Mass Spectrometry. The results indicate that the Re and Os contents are 0.901-9.794 ng/g and 7.3-189.5 pg/g, respectively. The Re-Os isotope isochron age is 155.6±3.6 Ma, which is consistent with the zircon U-Pb age (153-157 Ma) of StageⅡ medium-grained biotite granite of the Qitianling pluton on the east side of the deposit. It also indicates that the coal seam of the Longtan Formation is subjected to 'baking' by the Qitianling pluton, inducing the hot contact metamorphism and changing the raw coal near the Qitianling pluton to graphite to form a graphite deposit. The comparison of Re and Os content and Os isotopic composition between the graphite, coal and Qitianlign pluton demonstrates that the Re and Os in the graphite are mainly derived from raw coal. According to the initial Os isotope ratio of 0.686±0.032, it can be concluded that minor Os with low 187Os/188Os value was absorbed by carbonaceous material during the intrusion of coal seam by the Qitianling pluton.

The average content of uranium in sandstone-type uranium deposits is 635 μg/g, whereas the content of rhenium is 0.3-1.9 μg/g. Because of low rhenium content, now precise determination of low Re in high U ores remains unresolved. In this study, a method for the determination of trace Re in sandstone-type uranium deposits by Inductively Coupled Plasma-Mass Spectrometry was developed. Samples were digested by MgO sintering, and were then extracted by hot water. 103Rh was used as the internal standard element to eliminate the interferences of uranium, molybdenum and other matrix elements on Re. Under optimum conditions, the detection limit of trace rhenium is 0.12 ng/g, and the recovery is 99.8%. The method was validated by a variety of standard samples, the measured Re contents are in good agreement with the standard values. The relative standard deviation (RSD) is less than 1.5% for Re contents of 0.06-180.57 μg/g, which meets the requirement of determining trace Re in high U ores from sandstone type uranium deposits.

Isobaric ions interfere with two isotopes of Ag during determination by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), i.e., 90Zr16O1H and 91Zr16O on 107Ag, and 92Zr16O1H and 93Nb16O on 109Ag. Although an interference correction coefficient method was used for the calibration of the analytical results, the analytical errors remain serious. In the proposed method, samples were closed decomposed by nitric acid, hydrofluoric acid, and perchloric acid. Ammonia was used to precipitate Zr and the purified Ag was determined by ICP-MS using 103Rh as the internal standard. The interference caused by the residual Zr was calibrated by the interference coefficient method. The method has a detection limit (3σ) of 4.1 ng/g and relative standard deviation (n=12) ranging from 2.5% to 7.8%. Determination of Ag in 53 primary certified materials of geochemical exploration indicates no loss of Ag. Using ammonium as the reagent, separation of Zr and Ag was successfully achieved due to the formation of the stable Ag-ammonium complex and Zr-hydroxide precipitate. The separation of Ag from Zr has reduced the interferences of Zr on Ag. Compared with the high-pressure sealed decomposition method and the P507 extraction resin separation method, the closed sample decomposition method is much simpler with less acid used and a lower blank.

Recent researches of PAHs in sediment mainly were focused on offshore areas of Yangtze River estuary and coastal areas nearby Shanghai. However, there were few reports about the PAHs in waterway sediment from Qidong and Chongming Island. Surface waterway sediment samples (0-20 cm) were collected from Qidong and Chongming Island. Followed by extraction using accelerated solvent extraction techniques, then 14 PAHs were measured by means of HPLC-FLD in order to discuss and assess the distribution characteristics, possible sources and ecological risks of PAHs, respectively. The results showed that 14 PAHs could be detected in varying degrees for all sampling sites, Total concentrations of PAHs ranged from 83.43 to 5206.97ng/g with a mean concentration of 736.95 ng/g. 2, 3, 4-ring PAHs dominated in waterway sediment samples, and phenanthrene was the most abundant individual compound, accounting for 9.04% to 24.06% of total concentrations of PAHs, followed by fluoranthene and pyrene. The percentage of benzo[a]pyrene with high carcinogenicity in all samples was from 0.94% to 10.68%. Compared with other similar regions of the world, PAHs in waterway sediments from Qidong and Chongming Island of Yangtze River estuary were at moderate level. The sources of PAHs were apportioned using ratio analysis. Places with Phe(phenanthrene)/Ant(anthracene) < 10 and Fla(fluoranthene)/Pyr(pyrene)≥1 accounted for 56.25% of all sampling sites, indicated that PAHs in the studying areas mainly derived from combustion of fuel oil. Oil spill was another important source for some sampling sites located nearby harbours and wharfs. Some sites presented combined pollution characteristics. Comparing with ERL and ERM values for environment risk evaluation, some sampling sites of this area possessed a potential combined ecological risk to local organisms caused by PAHs.

Recent researches of PAHs in sediment mainly were focused on offshore areas of Yangtze River estuary and coastal areas nearby Shanghai. However, there were few reports about the PAHs in waterway sediment from Qidong and Chongming Island. Surface waterway sediment samples (0-20 cm) were collected from Qidong and Chongming Island. Followed by extraction using accelerated solvent extraction techniques, then 14 PAHs were measured by means of HPLC-FLD in order to discuss and assess the distribution characteristics, possible sources and ecological risks of PAHs, respectively. The results showed that 14 PAHs could be detected in varying degrees for all sampling sites, Total concentrations of PAHs ranged from 83.43 to 5206.97ng/g with a mean concentration of 736.95 ng/g. 2, 3, 4-ring PAHs dominated in waterway sediment samples, and phenanthrene was the most abundant individual compound, accounting for 9.04% to 24.06% of total concentrations of PAHs, followed by fluoranthene and pyrene. The percentage of benzo[a]pyrene with high carcinogenicity in all samples was from 0.94% to 10.68%. Compared with other similar regions of the world, PAHs in waterway sediments from Qidong and Chongming Island of Yangtze River estuary were at moderate level. The sources of PAHs were apportioned using ratio analysis. Places with Phe(phenanthrene)/Ant(anthracene) < 10 and Fla(fluoranthene)/Pyr(pyrene)≥1 accounted for 56.25% of all sampling sites, indicated that PAHs in the studying areas mainly derived from combustion of fuel oil. Oil spill was another important source for some sampling sites located nearby harbours and wharfs. Some sites presented combined pollution characteristics. Comparing with ERL and ERM values for environment risk evaluation, some sampling sites of this area possessed a potential combined ecological risk to local organisms caused by PAHs.

The majority of fat and impurities in animal tissues influence the analysis result for low concentration organic compounds. To overcome this issue, the animal sample was extracted by accelerated solvent extraction (ASE) with methylene chloride/acetone (V:V=1:1), which reduced the co-extraction lipids during the extraction process. Gel Permeation Chromatography (GPC) combined with solid phase extraction (SPE) was applied to remove lipids from the sample solution. The GPC can remove most of the macromolecular lipids in samples, and the SPE with florisil can sufficiently reduce fat and small molecule impurity. The accuracy and sensitivity of the method can be improved by this pretreatment process. The compounds, including 17 organochlorinated pesticides and 7 indicator polychlorinated biphenyls in animal tissue, can be simultaneously analysed by Gas Chromatography Mass Spectrometry. The recoveries of 25 of the target compounds were in the range of 81.6%-113.4% and the method detection limits for dry samples were 1.02-3.59 ng/g. These results were superior to those of the national standard. This method improved the purification effect of animal samples, reduced the method detection limit, and enhanced the accuracy. It can be used to quickly and accurately determine the low content of persistent organic pollutants in animals.

The majority of fat and impurities in animal tissues influence the analysis result for low concentration organic compounds. To overcome this issue, the animal sample was extracted by accelerated solvent extraction (ASE) with methylene chloride/acetone (V:V=1:1), which reduced the co-extraction lipids during the extraction process. Gel Permeation Chromatography (GPC) combined with solid phase extraction (SPE) was applied to remove lipids from the sample solution. The GPC can remove most of the macromolecular lipids in samples, and the SPE with florisil can sufficiently reduce fat and small molecule impurity. The accuracy and sensitivity of the method can be improved by this pretreatment process. The compounds, including 17 organochlorinated pesticides and 7 indicator polychlorinated biphenyls in animal tissue, can be simultaneously analysed by Gas Chromatography Mass Spectrometry. The recoveries of 25 of the target compounds were in the range of 81.6%-113.4% and the method detection limits for dry samples were 1.02-3.59 ng/g. These results were superior to those of the national standard. This method improved the purification effect of animal samples, reduced the method detection limit, and enhanced the accuracy. It can be used to quickly and accurately determine the low content of persistent organic pollutants in animals.

Trace impurity elements in high purity silver nitrate affect performance and quality. In order to improve the accuracy of analysis of modern testing technology for trace impurity elements, removing the silver by precipitant or deoxidizer to reduce matrix effect is the primary problem. A method has been developed for the simultaneous determination of 15 trace impurity elements in high purity sliver nitrate by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) with precipitation treatment. 10 mL 10 g/L citric acid and 5 g/L glycolic acid were used as complexing protectant to protect trace impurity elements during sample pretreatment. 12 mL 100 g/L ammonia chloride was used as precipitant to separate the matrix silver. The factors affecting the analytical results such as the concentration of complexing protectant and precipitant, the selection of isotope to avoid mass spectra interference, the matrix interference and the experimental blank values were comprehensively investigated and optimized. Under the optimized conditions, good linear relationships were obtained when the content ranges of Cu, Pb, Ni, Mn, Au, Pd, Pt, Rh, Ru and Ir were 0-100 ng/mL and Fe, Hg, Bi, Cr and Sn were 0-250 ng/mL. The detection limits of the method are 0.005-0.062 ng/g, the recovery rates are 94.1%-103.1% with precision of 0.6%-2.6% RSD (n=11). Compared with the existing analytical technique, the impurity elements and complex matrix could be separated completely using complexing protectant and precipitant. This new method is simple and practical with lower detection limits. Precision and accuracy meet the requirements of the simultaneous separation and determination of trace impurity elements in high purity silver nitrate samples.

Trace impurity elements in high purity silver nitrate affect performance and quality. In order to improve the accuracy of analysis of modern testing technology for trace impurity elements, removing the silver by precipitant or deoxidizer to reduce matrix effect is the primary problem. A method has been developed for the simultaneous determination of 15 trace impurity elements in high purity sliver nitrate by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) with precipitation treatment. 10 mL 10 g/L citric acid and 5 g/L glycolic acid were used as complexing protectant to protect trace impurity elements during sample pretreatment. 12 mL 100 g/L ammonia chloride was used as precipitant to separate the matrix silver. The factors affecting the analytical results such as the concentration of complexing protectant and precipitant, the selection of isotope to avoid mass spectra interference, the matrix interference and the experimental blank values were comprehensively investigated and optimized. Under the optimized conditions, good linear relationships were obtained when the content ranges of Cu, Pb, Ni, Mn, Au, Pd, Pt, Rh, Ru and Ir were 0-100 ng/mL and Fe, Hg, Bi, Cr and Sn were 0-250 ng/mL. The detection limits of the method are 0.005-0.062 ng/g, the recovery rates are 94.1%-103.1% with precision of 0.6%-2.6% RSD (n=11). Compared with the existing analytical technique, the impurity elements and complex matrix could be separated completely using complexing protectant and precipitant. This new method is simple and practical with lower detection limits. Precision and accuracy meet the requirements of the simultaneous separation and determination of trace impurity elements in high purity silver nitrate samples.

Trace elements in the carbonate of marine sediments carry abundant original geological information. However, there is no uniform standard method for the determination of carbonate in marine sediments. In this paper, an extraction method is described for five kinds of trace elements (V, Cr, Co, Ni and Sr) of carbonate phase in the marine sediments by using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), which is based on the modified seven steps extraction processes by Tessier. Two extraction agents (EDTA and NaAc) were used to extract carbonate fraction for marine sediment samples and standard materials. The results indicate that the NaAc cannot be used to fully extract the trace elements from the carbonate phase in sediments. The EDTA can better extract the carbonate phase of marine sediments, but organic complex metals were also extracted based on the strong complexation ability for metallic elements. In this experiment, we initially removed the ion exchange state by using NaCl and excluding the organic material by pyrophosphate (pH=10) which was an extractant with strong selectivity. Next, the terragenous carbonate of marine sediments was extracted by EDTA. The precision of the method was less than < 5%, the detection limit of each element was in the range of 0.5-4.3 ng/g, and the recoveries were between 88.0%-101.6%. Selectivity and stability of the method meet the requirements of geochemical sample morphological analysis.

A method for the simultaneous determination of the trace contents of As, Sb, Bi and Hg in the same solution by Hydride Generation-Inductively Coupled Plasma-Atomic Emission Spectrometry (HG-ICP-AES) was established by using 10% hydrochloric acid as the dissolved medium. The soil sample was dissolved in water bath with aqua regia for one hour, and then ascorbic acid-thiourea solution was added to reduce As and Sb in advance without influence on the content of Hg. The elements were determined by a new type self-designed hydride generator coupled with ICP-AES with 10% hydrochloric acid, 0.5 L/min carrier gas and 10 g/L NaHB4-NaOH as reductants. This method solved the problems of the inconvenience of multi-element determination and more reagent consumption. The sample pre-treatment and determination were easy, rapid and had no memory effect. The detection limits of the method were 0.01-0.06 ng/g, the recoveries of standard materials were between 92.0% and 102.0%, and RSD was less than 5%. This method is suitable for the simultaneous determination of the trace contents of As, Sb, Bi and Hg in environmental samples.