科研之友
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摘要
We developed a low-cost, demountable direct injection high. efficiency nebulizer (DIHEN) for inductively coupled plasma mass spectrometry (ICP-MS). It consisted of an enlarged microconcentric nebulizer based body, a tapered capillary (0.25 mm i.d. and 0.37 mm o.d., 30 mu m i.d. and 40 mu m o.d. at the tip), a hollow stainless steel tubing (0.5 mm i.d. and 2.0 mm o.d.) and two adapters made from polytetrafluoroethylene (PTFE), which were assembled by epoxy resin. The tapered capillary was reproducibly fabricated according to a flame. heated two. step drawing method. After immerging into boiling water, the epoxy resin became soft and the components could be taken apart simply. Then the broken or blocked sample capillary was replaced by a new tapered capillary with the same dimensions and then they were assembled again. The optimal sensitivity was obtained when the gas flow rate was 0.27 L/min with a sample uptake rate of 50 mu L/min and a forward power of 1500 W. The sensitivities, detection limits and precisions of the homemade DIHEN under optimal operating conditions are similar, or better than those obtained with the MicroMist nebulizer, to some extent, though the polymeric ion levels of the former are higher than those of the latter. The utility of the homemade DIHEN for the analysis of small. volume samples was demonstrated by microscale flow injection analysis of Pt in serum samples. Then the homemade DIHEN was further utilized to couple microchip electrophoresis to ICP-MS for iodine speciation. The cost of the homebuilt DIHEN is about 1% price of the commercial Meinhard DIHEN, and the demountable construction permits that the blocked or broken sample capillary could be conveniently renewed with the same capillary in dimensions, obtaining low cost and easy maintenance.
