Organomercury compounds, determination

Dry or wet sample digestion before FAAS determination (e.g. in organomercurial compounds determination as mercury or selenium sulphide determination as selenium). 

Agemian and Chau [55] have described an automated method for the determination of total dissolved mercury in fresh and saline waters by ultraviolet digestion and cold vapour atomic absorption spectroscopy. A flow-through ultraviolet digester is used to carry out photo-oxidation in the automated cold vapour atomic absorption spectrometric system. This removes the chloride interference. Work was carried out to check the ability of the technique to degrade seven particular organomercury compounds. The precision of the method at levels of 0.07 pg/1, 0.28 pg/1, and 0.55 pg/1 Hg was 6.0%, 3.8%, and 1.00%, respectively. The detection limit of the system is 0.02 pg/1. 

Ealy [ 75 ] also used conversion to alkyl mercury iodides for the gas chromatographic determination of organomercury compounds in benzene extracts of water. The iodides were then determined by gas chromatograph of the benzene extract on a glass column packed with 5% of cyclohexane-succinate on Anakron ABS (70-80 mesh) and operated at 200 °C with nitrogen (56 ml min-1) as carrier gas and electron capture detection. Good separation of chromatographic peaks was obtained for the mercury compounds as either chlorides, bromides, or iodides. The extraction recoveries were monitored by the use of alkylmer-cury compounds labelled with 203 Hg. 

Unlike THg, a limited data set about the occurrence of organomercury compounds in biota of the Ebro River has been noticed. MeHg concentrations were only determined in zebra mussel specimens in the Flix hot spot [32] as well as some fish species living in Flix dam (Diez, unpublished results). 

NMR has been applied to the determination of organomercury compounds in non-saline sediments and humic and fulvic acids in soil and saline sediments. 

Kimura and Miller [28] have also studied the decomposition of organic fungicides in soil to mercury vapour and to methyl- or ethylmercury compounds and devised methods for the determination of these compounds in the vapours liberated from the soil sample. The mixed vapours of mercury and organomercury compounds is passed successively through bubblers containing a carbonate-phosphate solution to absorb organic... 

Langmyhr et al. [45] have applied cold vapour atomic absorption spectrometry to the determination of organomercury compounds in soils and sediments. 

Cappon and Crispin-Smith [59] have described a method for the extraction, clean-up and gas chromatographic determination of alkyl and aryl mercury compounds in sediments. The organomercury compounds are converted to their chloroderivatives and solvent extracted. Inorganic mercury is then isolated as methylmercury upon reaction with tetramethyltin. The initial extract is subjected to a thiosulphate clean-up and the organomercury species are isolated as their bromoderivatives. Total mercury recovery was in the range 75-90% and down to lpg kg-1 of specific compounds can be determined. 

In mercury speciation studies, pressurized liquid extraction (PLE), microwave-assisted extraction (MAE), and supercritical fluid extraction (SEE) are employed [33]. In particular, methyl-mercury is extracted by the Westoo method [33,34], which consists in a leaching process with hydrochloric acid, the extraction of the metal chloride into benzene or toluene, the addition of ammonium hydroxide that converts the metal species to hydroxide and the saturation with sodium sulfate. Most of the HPLC methods reported in literature for the determination of organomercury compounds (mainly monomethyhnercury, monoethyhnercury, and monophenylmercury) are based on reversed... 

Krull, I.S., Bushee, D.S., Schleicher, R.G. and Smith, S.B. (1985) Determination of inorganic and organomercury compounds by high performance liquid chromatography-inductive ly coupled plasma emission spectrometry with cold vapour generation. Analyst, 111, 345-349. 

Liu, Y., Lopez-Avila, V, Alcaraz, M. and Beckert, W.E. (1994) Simultaneous determination of organotin, organolead, and organomercury compounds in environmental samples using capillary GC-AED./. High. Resol. Chromatogr, 17, 527-536. 

If derivatization of the native species is carried out, derivatization yields should also be assessed. In aqueous samples these yields are relatively easy to assess when a derivatized standard similar to the derivatized organomercury compound is available. Use of the standard addition method allows the derivatization yield to be determined. 

Mercury. Mercury Is a classic heavy metal occupational toxicant studied by Paracelsus and popularized in Lewis Carol s Alice in Wonderland. Both elemental and organomercury compounds are of great interest to Industrial hygienists. Elemental mercury is still routinely determined from acidic KMnO collection by dithizone complexation at 515 nm (6) (Table VI ). Surprisingly, Hg is not Included In P CAM 173. Elemental mercury has been determined by flameless AAS (P CAM 165) for urine,... 

The analyst has used an analytical method to determine the concentration of mercury in a sample of shellfish. The analytical method chosen might measure total mercury (the metal mercury and all its compounds) or it might only measure certain mercury species e.g. mercury(II) salts, organomercury compounds). Therefore, the method chosen may have a significant effect on the mercury concentration found in the sample. 

To date, the stractures of more than four hundred organomercury compounds have been determined by X-ray diffraction methods. Detailed reviews by Warden, Holloway, and Melknik, and Casas, have already been published covering the relevant literature up to the end of 1997. Consequently, only a representative set of recent examples will be discussed in this section. 

The 2-deoxyglucoside 6 can be prepared by cyclization of (2/ ,3/ ,4/ )-(Z)-1,3,4-tris(ben-zyloxy)-6-cyclohexyloxy-5-hexen-2-ol (5). The selective formation of the a- or /(-anomer depends on the configuration of the double bond. When the (Z)-enol ether is treated with mercury(II) trifluoroacctate in tetrahydrofuran at low temperature, and the resulting organomercury compound is cleaved with sodium borohydride, the 2-deoxyglucoside is obtained in 70 % yield and a 96 4 (a// ) mixture, as determined by HPLC analysis94. 

Fig. 2 Chromatogram of a standard mixture after complexa-tion with sodium diethyldithiocarbamate. Composition of the standard mercury dichloride, methylmercury chloride, ethyl-mercury chloride, methoxyethylmercury chloride, ethoxyethyl-mercury chloride, phenylmercury chloride, and tolymercury chloride. [Reprinted from A. Knochel and H. Potgeter, Interfacing supercritical fluid chromatography with atomic fluorescence spectrometry for the determination of organomercury compounds,/. Chromatogr. A 786 192 (1997). Copyright 1997, with permission from Elsevier Science.]...

Baeyens W, Leermakers M. 1989. Determination of metallic mercury and some organomercury compounds using atomic-absorption spectrometry after amalgamation on a gold column. J Anal At Spectrom 4(7) 63 5-640. 

Evans 0, McKee GD. 1988. Determination of mercury(II) and organomercury compounds by reversed-phase liquid chromatography with reductive electrochemical detection. Analyst 113(2) 243-246. 

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