Figure 3.

15d-PGJ₂ in human urine. (a) Mass chromatogram of 15d-PGJ₂ in human urine. Representative chromatogram obtained by NI-ESI^- MRM. Healthy human volunteers abstained from NSAID use for more than 5 days before urine collection. Asterisks denote isomers of [²H₄]15d-PGJ₂ present in the internal standard. The major detectable isomer is identified by shading (b) Formation of 15d-PGJ₂ by dehydration of PGJ₂ or PGD₂. Unlabeled PGD₂ or PGJ₂ (0.2 ng/ml) was added to human urine at T = 0 hour. Aliquots (5.0 ml) were analyzed at the indicated time points for loss of spike and concomitant formation of 15d-PGJ₂. The numbers above bars represent amount (%) of added PG remaining at the corresponding time point. (c) Failure to detect endogenous PGJ₂ in freshly voided urine. Representative chromatogram of PGJ₂ in urine. NI-ESI^- MRM of urine samples (5.0 ml + 1.0 ng [¹⁸O₂]-PGJ₂) that were SPE extracted within 15 minutes of voiding. HPLC mobile phase was 30% CH3CN (isocratic). Other parameters were identical to those used for 15d-PGJ₂. The PGJ₂ peak is shaded. Estimation of the threshold of PGJ₂ detection was based on the least integratable peak.