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This work describes a procedure using the recently proposed standard dilution analysis (SDA) calibration method for the determination of As, Cr and Ni in concentrated HNO 3 and HCl by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). Because of the low contaminant levels, and consequently low limits of detection required for these reagents (commonly used in trace element analysis and the semiconductor industry), samples were minimally diluted. The analysis of concentrated acids can result in matrix/transport effects, which may compromise accuracy in ICP-MS determinations. High-chlorine content samples are also challenging for As and Cr determination due to the formation of polyatomic species such as 40 Ar 35 Cl + and 35 Cl 16 OH + , which overlap the only As isotope, 75 As + , and the main Cr isotope, 52 Cr + , respectively. The combination of SDA and ICP-MS/MS was evaluated to overcome matrix, transport and spectral interferences in order to increase accuracy, precision and sample throughput. The performance of SDA was compared with the traditional methods of external standard calibration (EC), internal standardization (IS), and standard additions (SA). The limits of detection for SDA were calculated as 6, 10, and 30ngL -1 for As, Cr, and Ni, respectively. Recoveries for spike experiments using the new method were in the 90-114% range for all analytes. The procedure described here provides similar or even better analytical performance in comparison with EC, IS and SA., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A method for the determination of sulfur in biodiesel samples by inductively coupled plasma optical emission spectrometry which uses microemulsion for sample preparation and the summation of the intensities of multiple emission lines has been developed. Microemulsions were prepared using 0.5 mL of 20% v/v HNO(3), 0.5 mL of Triton X-100, 2-3 mL of biodiesel sample, and diluted with n-propanol to a final volume of 10 mL. Summation of the emission intensities of multiple sulfur lines allowed for increased accuracy and sensitivity. The amounts of sulfur determined experimentally were between 2 and 7 mg L(-1), well below legislative standards for many countries. Recoveries obtained ranged from 72 to 119%, and recoveries obtained for the 182.562 nm line were slightly lower. This is most likely due to its lower sensitivity. Using microemulsion for sample preparation and the summation of the intensities of multiple emission lines for the successful determination of sulfur in biodiesel has been demonstrated., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The applicability of thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was evaluated for direct determination of Cu, Cd and Pb in wines and grape juices. The developed procedure does not require preliminary acid digestion of the samples. The optimum conditions for determination of Cu, Cd and Pb in wines were studied and the performance was compared to those typically obtained by flame atomic absorption spectrometry (FAAS). A sample volume of 150 microL was introduced into a heated nickel tube at a flow rate of 0.54 mLmin(-1) and 0.14 molL(-1) HNO(3) was used as sample carrier flowing at 2.5 mLmin(-1) for determining all analytes. The effect of ethanol concentrations on Cu, Cd and Pb absorbance signals were studied. All determinations were carried out by adopting optimized conditions and quantification was based on the standard additions method. Limits of detection (LOD) of 12.9, 1.8 and 5.3 microgL(-1) (n=14) for Cu, Cd and Pb, respectively, were obtained for wine samples (3sigma(blank)/slope, n=14). Relative standard deviations (R.S.D., %) of 2.7, 2.1 and 2.6 for Cu, Cd and Pb, were obtained (n=6) for wine samples. The values determined for grape juice samples were similar to these ones. The analytical throughput was 45 determinations h(-1) and accuracy was checked by addition-recovery experiments.