We developed and validated an on-line reverse-phase two-dimensional LC/MS/MS (2D-LC/MS/MS) system for simultaneous determination of the levels of prostaglandin (PG) E(2) as well as PGF(2alpha) and its metabolite 13,14-dihydro-15-keto PGF(2alpha) (F(2alpha)-M) in human plasma. Analytes were extracted by a three-step solid-phase extraction. Samples were then analyzed by on-line 2D-LC/MS/MS with electrospray ionization in negative mode. The 2D-LC system is composed of two reverse-phase analytical columns with a trapping column linking the two analytical columns. While an acidic buffer was used for both separation dimensions, differing organic solvents were employed for each dimension: methanol for the first and acetonitrile for the second to increase resolving power. The 2D-LC/MS/MS method was highly selective and sensitive with a significantly lower limit of quantitation (0.5 pg/mL for PGE(2) and 2.5 pg/mL for PGF(2alpha) and F(2alpha)-M, respectively). Linearity of the 2D-LC/MS/MS system was demonstrated for the calibration ranges of 0.5-50 pg/mL for PGE(2) and 2.5-500 pg/mL for PGF(2alpha) and F(2alpha)-M, respectively. Acceptable precision and accuracy were obtained throughout the calibration curve ranges. This highly selective and sensitive method was successfully utilized to determine the endogenous levels of PGE(2), PGF(2alpha), and F(2alpha)-M in plasma samples from six (four male and two female) normal volunteers. The mean concentrations for each analyte were 0.755 pg/mL for PGE(2), 5.70 pg/mL for PGF(2alpha) and 9.48 pg/mL for F(2alpha)-M.

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This paper reports the quantitative method of vapor concentration in unsteady evaporating gasoline type spray with Laser Induced Exciplex Fluorescence(LIEF). The LIEF is an exciplex fluorescence method developed by Melton to visualize the liquid and vapor phases separately. In this study, iso-octane(92 vol%), benzene(4 vol%), and triethylamine(4 vol%) were used as a fluorescent agent that emit excited complex fluorescence that can optically separate fluorescence from the liquid phase and the vapor phase respectively. We tested the dependence of the fluorescence characteristics on the vapor concentration, ambient pressure, and ambient temperature when quantifying the vapor concentration. The relationship between the vapor concentration and the fluorescence intensity ratio was similar to the theoretical relationship. Furthermore, the relationship between the fluorescence intensity ratio and each parameter could be considered as a function of only its parameter. Since the fluorescence intensity is proportional to the laser incident light intensity and the emitted laser light has a Gaussian intensity distribution, the intensity distribution of the laser sheet light could be predicted, and the captured image could be corrected. For quantitative measurement, we used the image analysis method of vapor concentration quantification measurement of direct injection diesel spray developed by Senda et al. The quantitative distribution of vapor concentration was measured by applying the method to the results of simultaneous measurement of Mie scattering, exciplex fluorescence, and monomer fluorescence.

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