Objective:A gas chromatography(GC)method was established for the simultaneous determination of seven residual solvents in clopidogrel bisulfate,including methanol,acetone,isopropanol,dichloromethane,n-hexane,tetrahydrofuran and methylbenzene.Methods:The analysis was performed on an Agilent DB-1 capillary column(30 m ×0.32 mm,3.0 μm)under the programmed temperature.The carrier gas was high purity nitrogen,and the flow rate was 4.0 mL·min-1 with constant flow control.The detector was a hydrogen flame ionization detector(FID).The inlet temperature was 200 ℃,the detector temperature was 270 ℃ and the split ratio was 5∶1.The temperature of headspace injector was 85 ℃,and the equilibrium time was 20 min.Results:Seven residual solvents were separated completely.The linear relationship between peak area and the concentration range of seven residual solvents were good enough(r＞0.9993).The results of specificity,precision and recovery met the requirements.Conclusion:This method can be used for the determination of residual organic solvents in clopidogrel bisulfate.

Objective To evaluate the performance characteristics of the second trimester double-marker test for the detection of fetal Down's syndrome in mainland China. Methods This prospective national multi-centered study used alpha-fetoprotein (AFP) and free β-subunit of human chorionic gonadotrophin( free β-hCG)as the serum markers. From May 2004 to September 2006, 11 centers participated in the collection and analysis of maternal serum AFP and free β-hCG between 14 and 20+6 weeks of pregnancy. The screening results were calculated using the standard algorithm based on the standard database provided with the analytic software. Patients with an increased risk of Down's syndrome pregnancy (≥1/270) were offered genetic anmiocentesis. Outcomes of all pregnancies were obtained.Results A total of 66 132 singleton pregnancies were included in the study. The median maternal age was 27 years. At a cut-eft of 1 in 270, the detection rate (DR) based on a Caucasian database was 72% corresponding to a false positive rate (FPR) of 5%, and the DR based on the Chinese database was raised to 76% corresponding to an FPR of 5%. Conclusion The double-marker test using AFP and free β-hCG is an effective screen strategy for second-trimester detection of fetal Down's syndrome in mainland China. Ethnic variance exists between the Caucasian and Chinese populations. The accuracy of screening is increased by the use of race-specific medians.