Determination of trace mercury species by high performance liquid chromatography-inductively coupled plasma mass spectrometry after cloud point extraction.

A sensitive method for speciation analysis of inorganic mercury (Hg(2+)) and methyl mercury (MeHg(+)) has been developed by using high performance liquid chromatography (HPLC) combined with inductively coupled plasma mass spectrometry (ICP-MS) after cloud point extraction. The analytes were complexed with sodium diethyldithiocarbamate (DDTC) and preconcentrated by a non-ionic surfactant Triton X-114. Mercury species were effectively separated by HPLC in less than 6 min. The enhancement factors for 25 mL sample solution were 42 and 21, and the limits of detection were 4 and 10 ng L(-1) for Hg(2+) and MeHg(+), respectively. The developed method was successfully applied to the determination of trace amount of mercury species in environmental and biological samples.

Determination of ultra-trace amount methyl-, phenyl- and inorganic mercury in environmental and biological samples by liquid chromatography with inductively coupled plasma mass spectrometry after cloud point extraction preconcentration.

The cloud point extraction (CPE) preconcentration of ultra-trace amount of mercury species prior to reverse-phase high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS) detection was studied. Mercury species including methyl-, ethyl-, phenyl- and inorganic mercury were transformed into hydrophobic chelates by reaction with sodium diethyldithiocarbamate, and the hydrophobic chelates were extracted into a surfactant-rich phase of Triton X-114 upon heating in a water bath at 40 degrees C. Ethylmercury was found partially decomposed during the CPE process, and was not included in the developed method. Various experimental conditions affecting the CPE preconcentration, HPLC separation, and ICP-MS determination were optimized. Under the optimized conditions, detection limits of 13, 8 and 6 ng l(-1) (as Hg) were achieved for MeHg(+), PhHg(+) and Hg(2+), respectively. Seven determinations of a standard solution containing the three mercury species each at 0.5 ng ml(-1) level produced relative standard deviations of 5.3, 2.3 and 4.4% for MeHg(+), PhHg(+) and Hg(2+), respectively. The developed method was successfully applied for the determination of the three mercury species in environmental water samples and biological samples of human hair and ocean fish.

[Determination of copper, chromium and arsenic in wood and its products by high pressure digest-ICP-AES].

Sample preparation was studied, samples were sawn to be sawdust, screened by a 35 mesh sieve, dryed 4-5 h at 105 degrees C, and its homogeneity was tested by variance analysis. Sample pretreatment methods were investigated with wet decomposition, dry ashing, high pressure digest (including microwave-assisted closed digestion and steel liner PTFE vessel digestion). According to the comparative results, wet decomposition is fit for testing soluble copper, chromium and arsenic. Dry ashing and high pressure digest are fit for testing total copper, chromium and arsenic, but arsenic is easy to lose in dry ashing. Acidity effect and matrix effect were discussed. A method was proposed for the determination of total copper, chromium and arsenic in wood and its products by high pressure digest-ICP-AES. The detection limit of copper, chromium and arsenic was 1.2, 0.2 and 7.1 mg x kg(-1), respectively, RSDs were in the range of 0.2%-1.5%, and recoveries were between 92% and 106%. Using this method, more reasonable results will be given for controlling toxic substances from wood and its products and their wastes. This method has been applied to practical sample analysis.

[Determination of soluble heavy metal Pb, Cd and Cr in water based architectural coatings for indoor decorating and refurbishing materials by ICP-AES].

In this paper the authors have studied coexisting element interference and acidity effect in sample, corrected spectral overlapping interference and non-spectral interference by interference coefficient method and standard addition method respectively, and established a method for the determination of soluble heavy metal Pb, Cd and Cr in water based architectural coatings by ICP-AES. The method is accurate and of low detection limit, and can be applied to the inspection work of water based architectural coatings.

[PCR detection of transgenic elements in feed raw material].

Based on the heterogeneous genes usually used in transgenic crops, the PCR technique was performed with primers derived from CaMV 35S promoter (35S-promoter,originated from cauliflower mosaic virus), NOS terminator (nopaline synthase-terminator,derived from Agrobacterium tumefaciens), EPSPS (5-enolpyruvylshikimate-3-phosphate synthase) gene, and CryIA(b) (delta-endotoxin,evolved from Bacillus thuringiensis subsp. kurstaki) gene to detect transgenic agents from feed raw materials of soybean dregs and corn gluten meal, respectively. Endogenous corn Zein (a protein extracted from corn gluten) gene, soybean Lectin (chitin-binding protein) gene and negative, positive control were applied for avoiding false results. The method established here has been successfully applied in detecting transgenic elements in imported feed raw material.