Methylthiouracil methods

The most recent modification of the NBD-Cl method involves a further improvement in its qualitative support (616). It involves the infusion of the extract employed for thin-layer chromatography via an electrospray interface into a mass spectrometer operating in the multiple-stage mass spectrometry mode, thus allowing confirmation of suspect results. The cleanup of the thyroid gland samples was also performed with a selective extraction procedure, based on the specific complex formation of the thiouracil, methylthiouracil, propylthiouracil and phenylthiouracil, tapazole, and mercaptobenzimidazole residues with mercury ions bound in a Dowex 1-X2 affinity column. 

A mercurated affinity column was also employed by Schilt et al. (617) for sample cleanup in a method for the determination of residues of thiouracil, methylthiouracil, and propylthiouracil in cattle urine by gas chromatography and niuogen phosphorous or mass spectrometry detection. The presence of nitrogen... 

The addition of sodium acetate is not essential but was found to increase the sharpness of the end-point. This method has been adopted by the B.P for propylthiouracil and methylthiouracil. 

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