A method based on ultra high performance liquid chromatography-electrostatic field orbitrap high resolution mass spectrometry (UHPLC-Orbitrap HRMS) was established for the determination of genotoxic impurities 2, 6, and 12 in nifedipine. After extraction with methanol, the sample was injected into the UHPLC-Orbitrap HRMS system for analysis. An ACE EXCELTM 3 C18-AR column (150 mm×4.6 mm, 3 μm) was used for chromatographic separation. The mobile phase was methanol-0.1% formic acid aqueous solution (65∶35, v/v). The flow rate was 0.6 mL/min, while the column temperature and autosampler temperature were set as 35 ℃ and 8 ℃, respectively. The divert valve switching technique was used to protect the mass spectrometer. The six-way valve was set to divert the eluent of 7.5-11.6 min to waste and the rest of the eluent into the mass spectrometer. The Orbitrap mass spectrometer was coupled with the UHPLC system by an electrospray ion (ESI) source. The sheath gas and auxiliary gas flow rates were 60 and 20 arb (arbitrary units), respectively. The spray voltage was 3.5 kV, while the capillary temperature and auxiliary gas heater temperature were set as 350 ℃ and 400 ℃, respectively. The positive ion parallel reaction monitoring (PRM) scanning mode was adopted, and the mass spectral resolution was set to 35000 FWHM. The accurate masses of the [M+H]+ precursor ions of impurities 2, 6, and 12 were m/z 347.1230, 361.1026, and 347.1230, respectively. The accurate masses of the extracted [M+H]+ fragment ions of impurities 2, 6, and 12 were m/z 315.0968, 298.1069, and 315.0968, respectively. The normalized collision energies (NCEs) were optimized to 10%, 42%, and 10% for impurities 2, 6, and 12, respectively. The external standard method was utilized for quantitative analysis. The established method was validated in detail by investigating the specificity, linear range, limit of detection (LOD), limit of quantification (LOQ), recovery, precision, and stability. This method had good specificity, and the solvent did not interfere with the determination of impurities. The peak areas of impurities 2, 6, and 12 as well as their concentrations showed good linear relationships in the ranges of 0.2-100 ng/mL, with all correlation coefficients (r)≥0.9998. The recoveries of impurities 2, 6, and 12 at three levels (low, medium, and high) were in the range of 96.9%-105.0%, while the RSDs were between 1.21% and 5.12%. The LODs were 0.05 ng/mL and the LOQs were 0.2 ng/mL for all three impurities. This analytical method was used to determine impurities 2, 6, and 12 in three batches of nifedipine samples. Impurity 6 was not detected in the three batches, but impurities 2 and 12 were detected in all the three samples, and the detection amount was within the limit. The developed method is sensitive, fast, accurate, and easy to operate. It can provide a reference for the quality control of nifedipine by pharmaceutical companies and extend strong technical support for the supervision by drug regulatory authorities.
建立了测定硝苯地平中基因毒性杂质2、6和12的超高效液相色谱-静电场轨道阱高分辨质谱法(UHPLC-Orbitrap HRMS)。样品以甲醇为溶剂,提取后直接进样分析。采用ACE EXCELTM 3 C18-AR色谱柱(150 mm×4.6 mm, 3 μm)分离,流动相为甲醇-0.1%甲酸水(65:35, v/v),等度洗脱。质谱部分采用电喷雾电离(ESI)源。采用正离子平行反应监测(PRM)扫描模式,质谱分辨率为35000 FWHM,杂质2、6、12的[M+H]+母离子准确质量数分别为m/z 347.1230、361.1026、347.1230,提取[M+H]+碎片离子准确质量数分别为m/z 315.0968、298.1069、315.0968,归一化碰撞能量(NCE)分别为10%、42%、10%,外标法定量。对方法进行了详细的方法学验证,结果表明,该法专属性良好,溶剂对杂质测定无干扰;杂质2、6、12质量浓度与其峰面积在0.2~100 ng/mL范围内呈现良好的线性关系,相关系数(r)均≥0.9998;杂质2、6、12在低、中、高3个水平下的回收率为96.9%~105.0%, RSD为1.21%~5.12%,检出限均为0.05 ng/mL,定量限均为0.2 ng/mL。应用该方法对3批硝苯地平样品中的杂质2、6、12进行测定,3批样品均未检出杂质6,但均检出杂质2和杂质12,其检出量未超过限度。该方法灵敏、快速、准确,操作简便,可为药企对硝苯地平的质量控制提供参考,并为药监部门的监管提供有力的技术支持。
Keywords: genotoxicity; high resolution mass spectrometry (HRMS); impurities; nifedipine; ultra high performance liquid chromatography (UHPLC).