Determination of secnidazole in human plasma by high-performance liquid chromatography with UV detection and its application to the bioequivalence studies.

A simple, accurate, precise and sensitive HPLC-UV method was developed for the determination of secnidazole in human plasma. Secnidazole and tinidazole (IS) were extracted from 0.2 mL of human plasma by ethyl acetate. Secnidazole was then separated by HPLC on a Diamond C(18) column and quantified by ultraviolet detection at 319 nm. The mobile phase consisted of acetonitrile-aqueous 5 mm sodium acetate (30:70, v/v) containing of 0.1% acetic acid adjusted to pH 4.0, and the flow rate was 1.0 mL/min. The low limit of quantification was 0.1 microg/mL. The method was linear over the concentration range 0.1-25.0 microg/mL (R(2) = 1.000). The recovery of secnidazole from human plasma ranged from 76.5 to 89.1%. Inter- and intra-assay precision ranged from 3.3 to 10.7%. Secnidazole in plasma was stable when stored at ambient temperature for 8 h, at -20 degrees C for 2 weeks and at -20 degrees C for three freeze-thaw cycles. The developed method was successfully applied to the pharmacokinetic and bioequivalence studies between test and reference secnidazole tablets following a single 500 mg oral dosage to 20 healthy volunteers of both genders. Pharmacokinetics parameters T(max), C(max), AUC(0-)t, AUC(0-infinity), T(1/2) were determined of both preparations. The analysis of variance (ANOVA) did not show any significant difference between the two preparations and 90% confidence intervals fell within the acceptable range for bioequivalence. It was concluded that the two secnidazole preparations are bioequivalence and may be used interchangeably.

[Assessment of PCB pollution in spatial distribution and analysis of the PCB sources in sediments in China].

An assessment of the current state of pollution from polychlorinated biphenyls (PCBs) and PCBs spatial character in sediments are represented. The sources of PCBs and relative factors are also analyzed. Songhua River and Dalian Bay in Northeast, Baoding in Hebei Province, Ya-er Lake in Wuhan City, Pearl River and Taiwan Province in Southeast of China have relatively high level of PCBs, while most other regions have lower average concentrations of PCBs. Serious pollution of PCBs is found in some locations, most of which are harbors, industrial areas, the places where improper disposal of and leakage from PCB containers taken place Point source pollution is the common pattern of contamination, influenced primarily by local geographic, economic, management and historical factors, with Pearl River/Estuary as an example.