An approximate solution of the spontaneous potential well-logging equation for asymmetric rock layers structure and its error estimate are obtained.Based on the estimate,it can be found that the error grows as the ratio of the height of the enclosing rock to the breadth of the invaded zone decreases.To overcome this problem,using the transformation of coordinate,a new approximate solution is given.

In one-dimensional isentropic case,the interaction of a rarefaction wave and a shock wave in the same family is analyzed,using shock polar and characteristic trajectory.The properties of the disturbed waves and the reflected waves after interaction is obtained,and its relation with the relative strength of the initial waves is discussed.Moreover,using Riemann invariants and the relations between changing physical variables,the shape of characteristic curves in the interaction area is obtained.

Purpose To determine the contents of residual methanol, ethanol,acetone, aether, petroleum ether, ethylacetate, iodomethane, acetic acid, n-amylamine,diethyl oxalate and DMF in Tegaserod Maleate. Methods A simple capillary gas chromatography method was established with FID detector. The capillary column was HP-5, using temperature program; The residues were calculated by the external standard method. Results The linearities were fairly good. The average recoveries were 86. 87 % - 98. 45 % with RSD of 1. 34% - 6. 56%. The limit of detection was 0. 29 - 1. 06 ng. The contents of eleven residual organic solvents in four batches of samples were complied with the specification requirements. Conclusions After validation, the method was proved to be accurate,sensitive and reliable. It is suitable to be adopted in the analysis of the tested solvents.

AIM:To establish a reversed-phase HPLC method with fluorescence detection for determination of the concentration of propofol in human plasma. METHODS: Agilent 1100 HPLC instrument was used with the column : Diamonsil C 18(150 mm×4.6 mm,5 μm), Phenomenex Security Guard column(4 mm×3 mm). Plasma samples were precipitated with the thymol (internal standard) methanol solution. 20 μL of supernatant fluid was injected for HPLC analysis. The mobile phase was composed of acetonitrile-water(56:44,V/V).The flow rate was 1.5 mL·min -1. The fluorescence detective wavelengths were: λ ex=276 nm, λ em=312 nm. RESULTS: The standard curve equation was Y= 1.787C- 0.031 (r= 0.9997,n=9).The linear range was (0.02—8.0) mg·L -1. The average recovery was 98.71 %.Intra- and inter-day precision(RSD%) were all less than 4.2 %. The limit of detection was 4 μg·L -1(S/N=2). CONCLUSION:The RP-HPLC method is simple, sensitive and accurate for monitoring propofol concentration in clinical plasma samples.

AIM: To establish UV and HPLC methods to determine the content of tegaserod tablet. METHODS: HPLC method——the separations were obtained on a Diamonsil C18 column which was maintained at 40 ℃, the mobile phase was acetonitrile 1% sodium dodecyl sulfate (contain 0.95% acetic acid) (56∶44, V∶V), the flow rate was 2 mL·min -1 and the detection wavelength was 314 nm. UV method——absorption was determined at 314 nm. RESULTS: HPLC method——calibration was linear from 0.1-120 mg·L -1 ( r =0.9999). Within day and between day coefficients of variation were less than 3.1 % . The recovery was between 100.42 % - 103.82 % . UV method——calibration was linear from 2-20mg·L -1 ( r =0.9998). Within day and between day coefficients of variation were less than 1%. The recovery was between 101.06 %-103.02 %. CONCLUSION: HPLC and UV method both appear to be suitable for determination of the content of tegaserod tablet while we are apt to use the UV method for its simplicity if the related impurity is controlled well.