高效液相色谱法测定聚乳酸中乳酸单体残留量

目的通过高效液相色谱法(high performance liquid chromatography,HPLC)测定聚乳酸材料中乳酸单体的残留量,完善此类材料的质量评价方法。方法用三氯甲烷溶解聚乳酸材料样品后,加入等体积磷酸二氢钾水溶液(20 mmol/L,pH=2.87)涡旋振荡,静置分层后取上清液,采用C18 Synergi4u Hydro-RP 80A色谱柱,进样20μL,以流速0.6 m L/min,磷酸二氢钾水溶液为流动相,柱温30℃,紫外检测波长210 nm,外标法定量并进行方法学研究,包括液相色谱系统适应性、线性范围、检出限、定量限、回收率。结果本方法中理论塔板数为10660,拖尾因子为1.32,分离度为3.81,重复性相对标准偏差为0.54%(n=5),乳酸在浓度1.05~105μg/m L范围内与峰面积保持良好的线性关系(r=0.999979),检出限为0.42μg/m L,定量限为1.05μg/m L,萃取平均回收率为94.76%(n=6),其相对标准偏差为3.04%。聚乳酸样品中乳酸单体平均残留量为144.17μg/g。结论高效液相色谱法测定聚乳酸中乳酸单体残留量具有良好的线性范围,准确度高,重复性好,萃取回收率较高且操作简单,可用于聚乳酸材料中乳酸单体残留量测定。

Determination of lactic acid monomer residues in polylactide by high performance liquid chromatography

Objective To determinate lactic acid monomer residues in polylactide by high performance liquid chromatography( HPLC) ,and to perfect evaluation method of this kind of materials. Methods Polylactide was dissolved in trichloromethane,then monopotassium phosphate solution(20 mmol/L,pH=2.87) was added. The mixed solution was oscillated and then kept still. Lactic acid monomer residual in the supernatant was determined by high performance liquid chromatography with C18 Synergi 4u Hydro-RP 80A column. The injection volum was 20μL; the flow rate was 0. 6 mL/min; the mobile phases was monopotassium phosphate solution(20 mmol/L,pH=2.87);the column temperature was 30℃;the UV-light detectation wavelength was 210 nm. The methodology consisted of system suitability,linearity range,detectation limit,limit of quantitation, recovery rate. Results In this method,the theoretical plate number was 10660;the tailing factor was 1.32;the resolution was 3.81;the relative standard deviation of the repeatability was 0.54%( n=5); the concentration range 1. 05—105 μg/mL of lactic acid kept good linear relationships with peak area and the coefficient correlations were 0.999979%;the limit of detection was 0.42μg/mL; the limit of quantitation was 1.05μg/mL; the average extraction recovery rate was 94.76%( n=6) with relative standard deviation of 3.04%. The average content of lactic acid monomer residual in the sample was 144.17 μg/g. Conclusions This method is simple and has good linear relationship, high precision and repeatability,which can be applied to determinate lactic acid monomer residues in polylactide.