Determination of As, Hg and Pb in herbs using slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry.
Analysis of herbs for As, Hg and Pb has been carried out using slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) with flow injection vapor generation. Slurry containing 0.5% m/v herbal powder, 0.1% m/v citric acid and 2% v/v HCl was injected into the VG-ICP-MS system for the determination of As, Hg and Pb that obviate dissolution and mineralization. Standard addition and isotope dilution methods were used for quantifications in selected herbal powders. This method has been validated by the determination of As, Hg and Pb in NIST standard reference materials SRM 1547 Peach Leaves and SRM 1573a Tomato Leaves. The As, Hg and Pb analysis results of the reference materials agreed with the certified values. The precision obtained by the reported procedure was better than 7% for all determinations. The detection limit estimated from standard addition curve was 0.008, 0.003, and 0.007 ng mL(-1) for As, Hg and Pb, respectively.
Microextraction based on solidified floating organic drop coupled with ETAAS for the determination of lead in herbs
Abstract A rapid, inexpensive and practical solidified of floating organic droplet microextraction (SFODME) prior to electrothermal atomic absorption spectrometry (ETAAS) was proposed for lead (Pb) determination in herb samples. For SFODME procedure, 1-(2-pysidylazo)-2-naphthol was used as a complexing agent. Analytical parameters influencing the extraction efficiency, i.e. types and volume of extracting solvent, concentration of 1-(2-pyridylazo)-2-naphthol, pH, extraction temperature and time were optimized. Under the optimized conditions, LOD and LOQ were 0.064 and 0.214 μg L−1, respectively, and an enrichment factor was achieved at 18.71 with the relative standard deviation ranging from 1.3 to 2.5% (n=6). The proposed method was effectively applied to the determination of lead in Spinach leaves (SRM-1570a) and Thai herb samples with acceptable results.
Design and operation of an autosampler controlled flow-injection preconcentration system for lead determination by flame atomic absorption spectrometry
Flow-injection manifolds are described which allow the preconcentration of lead for flame atomic absorption determinations, using columns contained within the sample loop of an injection valve. An interface was designed which allowed the valves and pump in the system to be controlled by an autosampler which enabled precise timing of preconcentration and elution steps. The effects of sample flow rate, buffer pH and buffer type for preconcentration and eluent concentration and flow rate were investigated in order to obtain optimum performance of the system. A 50-times improvement in detection limits over conventional sample introduction was obtained for a sample volume of approximately 12 ml, preconcentrated for 150 s. The injection of eluent, as opposed to the use of a continuously flowing eluent stream, enabled this reagent to be conserved.