Determination of chromium, selenium, and molybdenum in a therapeutic diet.

Monitoring both the trace element and main element content of drugs forms part of their quality control. Chromium, selenium and molybdenum were determined in therapeutic diet samples by inductively coupled plasma/mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (ET-AAS). Samples were digested by high pressure microwave digestion or by ashing in oven. ICP-MS measurements have demonstrated that the chromium determination in liquid therapeutic diet should be estimated on the basis of 5 3 Cr. In solid samples in some cases the value for Cr was elevated in comparison with the Cr content found by ET-AAS. The content of selenium can be determined on the basis of 7 7 Se or 8 2 Se after appropriate interference correction. Molybdenum content was determined on the basis of 9 5 Mo. Control measurements were made by ET-AAS. For quality assurance purposes some of the samples were analyzed by a control laboratory.