BACKGROUND: This study describes a novel analytical method for simultaneously determining sarpogrelate and its metabolite (M-1) in human plasma, using liquid chromatography coupled with tandem mass spectrometry, with electrospray ionization in the positive ion mode. METHODS: Sarpogrelate, M-1, and labeled internal standard (d3-sarpogrelate) were extracted from 50 microL of human plasma by simple protein precipitation. Chromatographic separation was performed by using a linear gradient elution of a mobile phase involving water-formic acid (99.9:0.1, v/v) and acetonitrile-formic acid (99.9:0.1, v/v) over 4 min of run time on a column, with a core-shell-type stationary phase (Kinetex C18, 50 mm x 2.1 mm i.d., 2.6-microm particle size, Phenomenex, USA). Detection of the column effluent was performed by using a triple-quadruple mass spectrometer in the multiple-reaction monitoring mode. RESULTS: The developed method was validated in human plasma, with lower limits of quantification of 10 ng/mL for sarpogrelate and 2 ng/mL for M-1. The calibration curves of sarpogrelate and M-1 were linear over the concentration ranges of 10-2,000 and 2-400 ng/mL, respectively (R2>0.99). The carry-over effect, precision, accuracy, and stability of the method met the criteria for acceptance. CONCLUSIONS: A simple, fast, robust, and reliable analytical method was successfully developed and applied to the high-throughput determination of sarpogrelate and its metabolite in real plasma samples in a pharmacokinetic study of healthy subjects.
Calibration ; Chromatography, Liquid ; Humans ; Mass Spectrometry* ; Particle Size ; Plasma* ; Tandem Mass Spectrometry

We developed and assessed the performance of a new multiplex real-time PCR assay for the detection of all Chlamydia species and simultaneous differentiation of Chlamydia psittaci and Chlamydia pneumoniae—two important human respiratory pathogens—in human clinical specimens. Next-generation sequencing was used to identify unique targets to design real-time PCR assays targeting all Chlamydia species, C. psittaci, and C. pneumoniae. To validate the assay, we used a panel of 49 culture isolates comprising seven C. psittaci genotypes, eight C. pneumoniae isolates, seven other Chlamydia species, and 22 near-neighbor bacterial and viral isolates, along with 22 specimens from external quality assessment (EQA) panels and 34 nasopharyngeal and oropharyngeal swabs and cerebrospinal fluid, stool, and sputum specimens previously identified as positive or negative for C. psittaci or C. pneumoniae. The assays were 100% specific, with limits of detection of 7.64– 9.02 fg/μL. The assay results matched with historical assay results for all specimens, except for one owing to the increased sensitivity of the new C. psittaci assay; the results of the EQA specimens were 100% accurate. This assay may improve the timely and accurate clinical diagnosis of Chlamydia infections and provide a greater understanding of the burden of disease caused by these agents.