Determination of formoterol in rat plasma by liquid chromatography-electrospray ionisation mass spectrometry

A sensitive method for the determination of formoterol in rat plasma is described, using high performance liquid chromatographic separation with tandem mass spectrometry. Samples were purified using liquid-liquid extraction and separated on CAPCELL PAK C18 UG120 (2.0 x 150 mm) with a mobile phase consisting of a mixture of methanol- 50 mM ammonium hydrogen carbonate (1:1 v/v). Detection was performed with a TSQ 7000 mass spectrometer using positive ion electrospray ionisation, monitoring the shift from precursor ions for formoterol at m/z 344.9 to product ions of m/z 121.0. The limit of quantitation of the method was found to be 0.1 ng/ml, when using 0.1 ml plasma. Plasma concentrations of formoterol could be quantified from 0.15 to 7.01 ng/ml, allowing the analysis of samples up to 32 h after a single oral dose of formoterol fumarate (0.25 mg) to rats.

A high-precision selective determination method for free N-acetylneuraminic acid in human serum

We established a high-precision selective determination method for free N-acetylneuraminic acid in human serum, involving capillary gas chromatography-mass spectrometry with selected ion monitoring and specific separation on a Sep Pak silica cartridge. In contrast to the value of 800 ng/ml of N-acetylneuraminic acid previously reported by Haverkamp et al. (J. Haverkamp, R. Schauer, and M. Wember (1976) Hoppe-Seyler's Z. Physiol. Chem. 357, 1699), who used the thiobarbituric acid method, the present method gave a value of 194 +/- 96 ng/ml for 22 serum samples from normal Japanese male volunteers aged between 20 and 30 years. The mass fragmentogram of serum showed a good signal/noise ratio, and the measurement was very specific, accurate, and reproducible.