苯丁酸钠杂质c顶空气相线性应该怎么做 各位老师,新手求助。我正要做苯丁酸钠杂质C气相方法,参考EP上的方法,方法如下: pH (2.2.3) : 6.5 to 7.5. Dissolve 0.20 g in carbon dioxide-free water R and dilute to 10 mL with the same solvent. Impurity C. Gas chromatography (2.2.28). Silylation solution. To 2 mL of N,O-bis(trimethylsilyl)trifluoroacetamide R add 0.04 mL of chlorotrimethylsilane R and mix. Test solution. Dissolve 50.0 mg of the substance to be examined in 3 mL of water R and add 0.5 mL of hydrochloric acid R. Extract with 2 quantities, each of 5 mL, ofmethylene chloride R. Evaporate the combined methylene chloride extracts to dryness in a vial with a screw cap and add 0.5 mL of the silylation solution. Seal the vial and heat at 70 ± 5 °C for 20 min. Reference solution (a). Dissolve 5.0mg of sodium phenylbutyrate impurity C CRS in methylene chloride R and dilute to 10.0 mL with the same solvent. Reference solution (b). Dilute 1.0 mL of reference solution (a) to 10.0 mL with methylene chloride R. Place 1.0 mL of this solution in a vial with a screw cap, evaporate to dryness and add 0.5 mL of the silylation solution. Seal the vial and heat at 70 ± 5 °C for 20 min. Reference solution (c). Dissolve 10 mg of the substance to be examined in 25 mL of water R. To 3 mL of this solution add 0.1 mL of hydrochloric acid R. Extract with 2 quantities, each of 5 mL, of methylene chloride R. Combine the methylene chloride extracts in a vial with a screw cap and add 2 mL of reference solution (a). Evaporate to dryness and add 0.5 mL of the silylation solution. Seal the vial and heat at 70 ± 5 °C for 20 min. Column: — material: fused silica; — size: l = 25 m, Ø = 0.25 mm; — stationary phase: poly(dimethyl)(diphenyl)siloxane R (film thickness 1.0 μm). Carrier gas: helium for chromatography R. Flow rate: 0.9 mL/min. Split ratio : 1:100. Temperature : Time (min) Temperature (°C) Column 0 - 5 50 5 - 27 50 → 270 27 - 32 270 Injection port 270 Detector 270 Detection: flame ionisation. Injection: 1 μL. Relative retention with reference to phenylbutyrate (retention time = about 20 min): impurity C = about 0.98. System suitability : reference solution (c) : — resolution: minimum 3.0 between the peaks due to impurity C and phenylbutyrate. Limit: — impurity C: not more than the area of the corresponding peak in the chromatogram obtained with reference solution (b) (0.1 per cent).