Abstract:A solid phase preconcentra- tion method has been developed using hydroxyl multi-wall carbon nanotubes (MWNTs) as the absorbent. The method was opti- mized for the determination of rare earth elements (REEs) in deep groundwater samples by inductively coupled plasma mass spectrometry (ICP-MS). The effects of the experimental para- meters, including pH, eluent con- centration and volume, flow rates of sample and eluent solutions, and the sample volume on the recoveries of the analytes were examined in detail. Under opti- mum conditions, REEs can be quantitatively retained by MWNTs when the pH exceeds 3.0 and are then eluted com- pletely with 1% HNO3. The detection limits of this method ranged from 0.31 ng L-1 to 1.2 ng L-1 and the relative standard devi- ations (RSDs) were less than 5%. The method was validated using a certified reference material and was applied for the determina- tion of REEs in deep groundwater samples with satisfactory results.

Abstract:Investigation of the iodine species is important to better understand the sources and mobilization processes of high- iodine groundwater. A fast and sensitive method for the deter- mination of iodate (IO3–) and iodide (I–) in groundwater using an improved ion chromatogra- phy method coupled with induc- tively coupled plasma mass spectrometry (IC-ICP-MS) is described. To shorten the sepa- ration time of iodine species, a short anion-exchange column, Dionex AG-19, was examined as the analytical column. Isocratic elution using 30 mM KOH facili- tated the chromatographic sepa- ration of IO3– and I– within one minute, reducing the time in comparison to previous IC-ICP- MS methods with conventional long IC columns (i.e., Hamilton X-100 or Dionex AS-16) by 90%. Moreover, the low analytical sensitivity of iodine, due to its high ionization potential (10.08 eV), was improved five-fold by addition of small amounts of CH4 to the Ar plasma. The detection limit was 0.005 μg L–1 for IO3– and 0.006 μg L–1 for I–, while the relative standard deviation for five injections of 0.2 μg L–1 I– or IO3– was 1.2–3.3%. The analyti- cal results for three water stan- dard reference materials were in agreement with the certified values. The proposed method was successfully applied to the determination of I– and IO3– in seven shallow groundwater sam- ples collected from the Datong Basin, Northern China. The dis- tributions of the iodine species, differing from mountain front plains to flat alluvial plain regions, indicate that the mobi- lization process of iodine is asso- ciated with complex redox conditions.

Abstract:In this work, a novel method was developed for the simultane- ous determination of different volatile elements (refractory Cr, medium volatile Cu, and easily volatile Cd) in high purity zirco- nium dioxide (ZrO2) by in situ matrix removal and electrother- mal vaporization inductively cou- pled plasma mass spectrometry (ETV-ICP-MS). A polytetrafluoro- ethylene slurry (PTFE) as a chem- ical modifier not only enhanced the difference in the volatility between the analytes and the matrix for in situ matrix removal, but also results in their similar vaporization behaviors of the different volatile elements (Cr, Cu, and Cd) for their simultane- ous determination. Under opti- mum operating conditions, the detection limits (DLs) for Cr, Cu, and Cd were 2.5, 9.8, and 3.4 ng g-1 with relative standard devia- tions (RSDs) of less than 6.2%, respectively. The calibration graphs of the analytes were linear over three orders of magnitude. This method was applied to the simultaneous determination of the different volatile elements Cr, Cu, and Cd in high purity ZrO2, and the results were in good agreement with those obtained by conventional pneumatic nebu- lization (PN) ICP-MS after separa- tion of the matrix with a solvent extraction procedure.

Abstract:An inductively coupled plasma atomic emission spectrometry- (ICP-AES) based method was developed for the direct determi- nation of phosphorus (P) and sul- phur (S) in stainless steel samples. It involved identification of differ- ent analytical lines of P and S and investigation of their analytical performance including detection limit, sensitivity, linear dynamic range, etc. Iron and chromium, being emission-rich major con- stituents of stainless steel, their contribution on the trace level determination of S and P was also investigated. The energy disper- sive X-ray fluorescence (EDXRF) spectroscopic technique was also used for comparative study. The P 177.495-nm and S 180.731-nm lines were found to be suitable for their determination in stain- less steel by ICP-AES, whereas the Kα lines were used for the EDXRF study. Based on the devel- oped methodology, five stainless steel samples were analyzed by ICP-AES and EDXRF, and the results were found to be satisfac- tory. The methodology was also validated by using certified refer- ence materials.

Abstract:In this study, toxic heavy metal contamination in dust sam- ples obtained from different streets in Denizli, Turkey, was monitored. The areas selected include heavy, moderate, and normal traffic flow, building con- struction sites and other indus- trial activities near roads, car parks, school gardens, health cen- ters, and hospitals. The metals were determined by flame atomic absorption spectrometry. The concentration ranges were Cu at 20.4–147.4 μg g-1, Cr at 9.9–75.0 μg g-1, Ni at 22.8–86.2 μg g-1, Pb at 14.4–145.3 μg g-1, and Mn at 52.3–158.3 μg g-1. The Cd content for all dust samples was below 0.1 μg g-1. According to the geoaccumulation index (Igeo) clas- sification, Cr and Mn were pre- sent at the lower level (0

Abstract:A novel method was devel- oped for the selective determina- tion of lead (Pb) in environ- mental samples by displacement dispersive liquid-liquid microex- traction (D-DLLME) combined with graphite furnace atomic absorption spectrometry (GFAAS). This D-DLLME method involves two steps of dispersive liquid-liquid microextraction (DLLME). Firstly, Zn2+ reacted with diethyldithiocarbamate (DDTC) to form the Zn-DDTC complex and was then extracted with the DLLME procedure. Then the sediment phase was dispersed into the sample solution contain- ing Pb2+ with a dispersive sol- vent; then another DLLME procedure was carried out. Since the stability of Pb-DDTC is higher than that of Zn-DDTC, Pb2+ can displace Zn2+ from the pre- extracted Zn-DDTC complex and be preconcentrated into the sedi- ment phase. The interference from co-existing metal ions with a lower DDTC complex stability was largely eliminated as they cannot displace Zn2+ from the Zn-DDTC complex. Under the optimal conditions, the limit of detection was 35 ng L?1 (3σ) for lead, and an enhancement factor of 91 was achieved with a sample volume of 5.0 mL. The proposed method has been successfully applied to the determination of trace lead in environmental sam- ples with satisfactory results.