Determination of americium-241 in urine

A technique has been developed for the determination of americium 241 in urine by a radiochemical purification of the nuclide from uranium (upon co-precipitation of americium 241 with calcium and lanthanum), plutonium, thorium, and polonium 210 (upon co-precipitation of these radionuclides with zirconium iodate). alpha-Radioactivity was measured either in a thick layer of the americium 241 precipitate with a nonisotope carrier or in thin-layer preparations after electrolytic precipitation of americium 241 on a cathode.     

Determination of eumelanin in human urine

Normal and malignant melanocytes produce melanins and melanin-related metabolites, most of which are retained in the cells but some are secreted into the blood and then excreted in the urine. In this study, we developed a method to measure levels of eumelanin in urine samples and evaluated its clinical significance in comparison with the melanin-related metabolites 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MI2C) and 5-S-cysteinyldopa (5-S-CD), and with pheomelanin, measured after degradation as 4-amino-3-hydroxyphenylalanine (4-AHP). The method is based on the production of pyrrole-2,3,5-tricarboxylic acid (PTCA) on permanganate oxidation of eumelanin, followed by quantification by liquid chromatography. For 118 urine samples from 10 control subjects, mean urinary excretions of PTCA, 6H5MI2C, 5-S-CD and 4-AHP were 19, 67, 37 and 59 micromol/mol creatinine respectively. In melanoma patients (n = 45), the mean urinary excretions of PTCA, 6H5MI2C, 5-S-CD, and 4-AHP were 91, 926, 4070 and 3530 micromol/mol creatinine respectively. Median level of PTCA in melanoma patients was elevated 2.1-fold compared with control subjects. The degrees of elevation for 6H5MI2C, 5-S-CD, and 4-AHP were 1.8-, 22- and 6.2-fold respectively. Thus, although urinary PTCA is of little clinical value in following the progression of melanoma, urinary 4-AHP appears to be of considerable value in this respect.     

Determination of ophidine in human urine

Ophidine (β-alanyl-3-methylhistidine) was first detected in the urine of two patients and later in two members of the laboratory staff loaded with whale meat, by column chromatography, high-voltage paper electrophoresis and two-dimensional paper chromatography.The ophidine peak was detected between homocarnosine and dimethylarginine using a lithium buffer gradient in column chromatography. In paper chromatography the ophidine spot was detected at a position close to anserine and homocarnosine. The ophidine in the urine from the patients was of dietary origin since it was absent in the urine a few weeks later.