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.
Green synthesized carbon quantum dots from Prosopis juliflora leaves as a dual off-on fluorescence probe for sensing mercury (II) and chemet drug.
In this article, a facile and green dual fluorescence sensor was developed for mercury and chemet as an anti-poisoning drug for heavy metal ions. The method is based on "off-on" fluorescence of carbon quantum dots (CQDs) prepared from Prosopis juliflora leaves as a green and low cost source. The synthesis of CQDs was easily performed with a rapid one pot process and the prepared CQDs exhibited a blue luminescence with a 5% quantum yield. The off fluorescent is observed in the presence of different concentrations of mercury (II) that is specifically recovered with the addition of chemet. The gradually recovered fluorescence is due to the high affinity of chelating property of succimer drug towards mercury (II) with a good restoration. Under the optimized condition, two linear calibrations were validated in the range of 5-500 ng mL-1 and 2.5-22.5 ng mL-1 for Hg (II) and chemet, respectively. The limit of detection (LOD) based on 3Sb was 1.26 ng mL-1 (or 6.3 nM) for Hg (II) and 1.4 ng mL-1 for chemet. The relative standard deviation of the fluorescent probe for 50 ng mL-1 of Hg (II) and 10 ng mL-1 of chemet was 4.5% and 1.3% (n = 10), respectively. This methodology was applied to successful measurements of Hg (II) and chemet in the water and human serum samples, respectively.
Novel method for the determination of the methoxyl content in lignin by headspace gas chromatography.
The paper reports on a headspace gas chromatographic (HS-GC) method for the determination of methoxyl in lignin. The method involves the quantitive cleavage of methoxyl with hydroiodic acid (HI) to form methyl iodide in a closed headspace sample vial at 130 °C for 30 min. After HI has been added, the sample is neutralized by injecting a sodium hydroxide solution; the methyl iodide in the vial was determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD < 0.69%) and accuracy (RSD < 3.5%) for the quantification of methoxyl content in lignin. The present method is simple and accurate and can be used for the efficient determination of methoxy1 content in lignin and related materials.