Profiling of prostaglandin biosynthesis in biopsy fragments of human lung carcinomas and normal human lung by capillary gas chromatography-negative ion chemical ionization mass spectrometry

Methods for the profiling of prostaglandin F_2α (PGF_2α), prostaglandin D₂ (PGD₂), prostaglandin E₂ (PGE₂), thromboxane 3₂ (TxB₂) and 6-keto-prostaglandin F_1α (6KPGF_1α) biosynthesis in tissue samples of clinical origin by capillary gas chromatography- negative ion chemical ionization mass spectrometry (CGC-NICIMS) are detailed. Alquouts (25μ1) of incubates (1 ml volume) of human lung carcinoma and normal lung tissue fragments (total protein content = 0.2 to 2.0 mg) were derivatized for vapor phase analysis in the presence of 0.75 to 1.60 ng of tetradeuterated analogs of PGE₂, PGF_2α and 6KPGF_1α without prior extraction and/or chromatography. The derivatized analytes and internal standards were detected by simultaneous monitoring of ions at six different masses characteristic for each of the derivatized prostanoids. The inter-sample and intra-sample coefficients of variantion for the assay method were typically less than 12%. The analysis of biological samples were completed with less than 2.5% of each derivatized sample per injection. The samples were of adequate purity for the identification and quantitation of each of the eicosanoids. The methods described in this report are highly sensitive with detection limits of 0.1 to 0.2 picograms per injection. The analytical procedures provide the basis for comparisons of the qualitative and quantitative profiles of prostaglandin biosynthesis and should be adaptable for use in a variety of biological and clinical studies.