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The speciation and quantification of organosilicon compounds at sub-ppm levels in environmental and industrial samples require the separation of the compounds of interest coupled with a sensitive, selective detector. The combination of high-performance liquid chromatography (HPLC) for separation and inductively coupled plasma atomic emission spectrometry (ICP-AES) for detection is ideal for the determination of a wide variety of organosilicon compounds. The HPLC-ICP combination was used in two modes: separation of non-polar, high molecular mass poly(dimethylsi1oxane) polymers by size-exclusion chromatography with tetrahydrofuran or xylene as the mobile phase, and separation of polar, low molecular mass silanols by reversed-phase HPLC with water-acetonitrile as mobile phase. Samples analysed included water and extracts of sludge and soils. The coupled system detection limit for poly(dimethylsi1oxane) is approximately 4-5 ng of Si, depending on the molecular mass distribution. The detection limit for a series of methylsilanediols is 1 4 ng of Si. An important feature of this work is that the analyses were performed using commercial HPLC and ICP equipment, with no modifications to hardware or software, and routinely employed solvents that are traditionally considered 'difficult' for ICP-AES. The equipment was interfaced and operating daily in less than 2 weeks from the beginning of the project. The ease of coupling readily available commercial equipment makes HPLC-ICP a viable technique for routine use in industrial and commercial analytical laboratories.

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The quantitative determination of Gd-containing magnetic resonance imaging (MRI) contrast agents in animal tissues is performed by both ICP-AES and ICP-MS. While ICP-AES has been used to determine Gd-containing contrast agents by other workers, no published methodology has been found. An accurate and precise method using nitric acid and microwave digestion for sample preparation is described. Dosed rat tissue, blood and plasma were measured by both ICP-AES and ICP-MS. The ICP-AES method is excellent for screening Gd levels and quantitative determination of concentrations above 400 ng ml-1, but it lacks the sensitivity to measure agent concentrations in low dose MRI studies. This work demonstrates that ICP-MS has the needed sensitivity to replace radiotracer methods currently used for low dose studies, while maintaining the accuracy and precision of results obtained by ICP-AES. Gadolinium detection limits in tissue were 0.04 mumol of Gd per kg of tissue, an order of magnitude lower than studies using radiotracer techniques.

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