TLC Separation and Identification of Heavy Metals Present in Cotton Material

JPC – Journal of Planar Chromatography – Modern TLC - Optimization of the separation and identification of heavy metals present in cotton material has been performed by...     

Investigation of mercury speciation in lichens.

Epiphytic lichens have long been considered to be reliable bioindicators of air pollution. In the present study only one lichen species, Hypogymnia physodes (L.) Nyl., was chosen; this species is very often used for biomonitoring in Europe. Total mercury and methylmercury were determined in lichens taken from various polluted and unpolluted locations in Slovenia, including a mercury mining area around Idrija. Additionally, total gaseous mercury in air was also determined at several sampling points.     

Sample preparation in analysis of pharmaceuticals

Sample preparation is a very important and essential step in environmental analysis. This article presents an overview of extraction methods for environmental samples, focusing especially on pharmaceuticals as there is great concern about them as pollutants.     

A modified method for the determination of methylmercury by gas chromatography

A simple modification of the West?? extraction procedure for methylmercury and its determination by gas chromatography (GC) is presented. The cysteine clean-up step has been modified, with use of cysteine-impregnated paper instead of cysteine solution. Methylmercury bromide is extracted from the sample into toluene and is selectively adsorbed on the cysteine paper. Interfering compounds are washed from the paper with toluene. The isolated methylmercury is set free with sulphuric acid containing bromide, extracted into benzene and determined by GC. The modification of the extraction procedure results in good recovery and reproducibility for various biological and environmental samples, good sensitivity with a detection limit of 0.1 ng/g, avoidance of difficulties arising from emulsion formation, cleaner chromatograms, and faster analysis. It is particularly suitable for determination of low levels of MeHg.     

Certification of total mercury and methylmercury concentrations in mussel homogenate (Mytilus edulis) reference material, IAEA-142

Due to the increased demand for new reference materials certified for total and methylmercury (MeHg) a sample of mussel homogenate (IAEA-142) has been prepared. Thirteen experienced laboratories reported results for total Hg of which 9 laboratories also reported results for MeHg content. Laboratories reporting MeHg results used various isolation techniques (solvent extraction, saponification, acid leaching, ion-exchange separation, and distillation) and detection systems (cold vapour atomic absorption spectrometry (CV AAS), cold vapour atomic fluorescence spectrometry (CV AFS), gas chromatography with electron capture detector (GC/ECD) and HPLC with CV AAS detector). In the case of total Hg, most of the laboratories used acid digestion, only two used alkaline dissolution, followed either by CV AAS or CV AFS. One laboratory used neutron activation analyses with radiochemical separation. The data received were in good agreement. The value for total Hg was certified to be 126 ng/g, with a 95% confidence interval from 119 to 132 ng/g. For MeHg the certified value of 47 ng/g expressed as Hg was assigned, with a 95% confidence interval from 43 to 51 ng/g. Stability testing has shown that both total and MeHg are stable if samples are stored in a dry and dark place at room temperature. The sample is now available as a certified reference material and is, in particular, useful for quality control measurements of Hg and MeHg in mussel samples at low concentration levels.