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.
Determination of Selected Elements in Aqueous Extractions of a Traditional Chinese Medicine Formula by ICP-MS and FAAS: Evaluation of Formula Rationality
Eight elements (Mg, Fe, Al, Ti, Mn, Co, Cu, and Zn) in Bai-Hu-Tang, an aqueous extraction of a traditional Chinese medicine formula consists of four crude drugs, were analyzed quantitatively by inductively coupled plasma mass spectrometry and flame atomic absorption spectrometry. The method was validated and the rationality of this formula was confirmed for enhancing dissolution of Mg, Fe, Cu, Mn, and Zn in the extraction while reducing that of Al and Co. By employing multivariate statistical techniques, data were classified and relationships among elements content in samples of different composition were revealed.
Interaction of Diclofop-Methyl and MCPA on Wild Oats (Avena fatua)
Diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoate} loses part of its activity on wild oats (Avena fatua L.) when it is applied in combination with ester or amine formulations of MCPA {[4-chloro-o-tolyl)oxy] acetic acid.} Uptake of diclofop-methyl is reduced in the presence of commercial formulations of MCPA, particularly amine formulations, which are only partly compatible with the diclofop-methyl formulation. With added MCPA, regardless of formulation, hydrolysis of diclofop-methyl to the acid diclofop is slowed down, both in intact wild oat plants and in a crude leaf extract. At the same time, conversion of any acid formed to inactive conjugates is accelerated in the presence of MCPA. It is concluded that the loss of activity of diclofop-methyl by MCPA can be accounted for by the effects of MCPA on uptake and metabolic conversion of diclofop-methyl.