Masanao Ozaki

Direct determination of trace fluorine in milk by aluminum monofluoride molecular absorption spectrometry utilizing an electrothermal graphite furnace

Abstract The determination of ultratrace levels of fluorine in bovine milk has been investigated by molecular absorption spectrometry using aluminum fluoride formed in an electrothermal graphite furnace. Aluminum (0.01 M, 20 μl, strontium solution (0.1 M, 10 μl) and milk sample (10 μl) were applied in the graphite furnace, and after drying and ashing, the furnace was heated at about 2700 K in 7s. Molecular absorption of aluminum monofluoride was measured at 227.45 nm, where simultaneous background correction was made with a deuterium lamp. The content of 0.033 μg F ml −1 was found for commercial bovine milk.

Determination of a new calcium antagonist and its main metabolite in plasma by thermospray liquid chromatography-mass spectrometry

A highly sensitive thermospray liquid chromatographic-mass spectrometric method has been developed for the simultaneous determination of FRC-8653 (I), a new calcium antagonist, and its main metabolite (M-4) in plasma. A deuterated analogue of I was added to the plasma as the internal standard. After the purification and concentration of the plasma sample on bonded-phase disposable columns, the extract was injected into the thermospray liquid chromatograph and analysed by selected-ion monitoring mass spectrometry. The calibration curves obtained were linear over the concentration range 0.5-100 ng/ml. The limits of quantification are 0.5 ng/ml for I and 1 ng/ml for M-4 in plasma, which are sufficient to evaluate plasma concentrations after oral administration to rats.