色谱分析中样品浓度对保留时间的影响

目的：采用反相高效液相色谱法（RP-HPLC法）测定头孢克肟,研究样品浓度对头孢克肟保留时间的影响。方法：采用WatersSymmetry-C18色谱柱（4.6mm×150mm,5μm）;流动相：水-乙腈[73.5∶26.5（10%四丁基氢氧化铵25ml加水至1000ml,用85%磷酸调节pH至7.0）];检测波长：254nm;流速：1.0ml/min。结果：头孢克肟浓度为0.005mg/ml时平均保留时间为12.325min;浓度为0.500mg/ml时平均保留时间为11.895min,平均差为0.428min,经统计学处理,有显著性差异（P〈0.01）。结论：实验结果表明,头孢克肟浓度相差100倍时,保留时间相差3.47%,即：当头孢克肟浓度达到一定高度时,保留时间会随着浓度的增加而缩短,初步研究显示这种现象具有普遍性。

The effect on retention time from sample concentration in chromatograph

Objective：To research sample concentration and the chromatographic retention time relationships by using RP-HPLC determination of cefixime. Methods：The Waters Symmetry-C18 （4.6 mm×150 mm,5 μm） column was used. The mobile phases consisted of water and acetonitrile [（73.5∶26.5）,10% tetrabutyl ammonium hydroxide 25 ml water to 1 000 ml,with 85% phosphoric acid adjusted pH to pH=7.0],the flow rate was 1.0 ml/min and the detection wavelength was at 254 nm. Results：The concentration of cefixime 0.005 mg/ml the average retention time was 12.325 min; concentration of 0.500 mg/ml the average retention time was 11.895 min,both mean difference 0.428 min,after statistical,difference is very noticeable （P 〈0.01）. Conclusion：The experimental results show that the concentration of cefixime difference between a hundred times,the retention time difference of 3.47%. Namely：When the cefixime concentration reaches a certain height,retention time will be shortened along with the concentration increases. Preliminary studies have shown that this phenomenon is universal.