Abstract：
Due to their potential adverse health effects, some N-nitrosamines in drug products are strictly regulated with very low maximum daily intake limits. Nitrosamines can be formed from the reaction of nitrite and secondary or tertiary amines when both species co-exist in the drug synthesis or formulation process. One key strategy to mitigate nitrosamine risk in drugs is to select low-nitrite containing pharma excipients for formulation. It is necessary to develop a sensitive method for trace nitrite determination in pharma excipients as it enables drug producers to study nitrosamine formation kinetics and select excipient suppliers. This study details the development and validation of a two-dimensional ion chromatography mass spectrometry (2D-IC/MS) method for trace nitrite determination in hydroxypropyl methylcellulose (HPMC), one of the most important pharmaceutical excipients used in many drug formulations. The 2D-IC system was operated in heart-cutting mode with a concentrator column coupling the two dimensions. A standard bore anion-exchange column was used in the first dimension (1D) to enable a large volume injection for increased sensitivity and provide improved resolution between nitrite and the interfering chloride peak. A high efficiency microbore anion-exchange column with different selectivity was used in the second dimension (2D) to resolve nitrite from other interfering species. The use of 2D-IC resulted in significantly improved resolution, solving the sensitivity loss issue due to ion suppression from an otherwise 1D separation. MS detection with selective ion monitoring and isotope labeled nitrite internal standard further improve the method specificity, accuracy, and ruggedness, as compared with conductivity detection. For trace determination, it is also extremely important to have a clean blank. For this purpose, a novel cleaning procedure using a strong anion wash was developed to remove nitrite contamination from labware. The optimized method was validated with linearity of nitrite in the concentration range of 18.5-5005.8 ng/g having a regression coefficient of >0.9999, precision with RSD at 3.5-10.1 % and recovery of 90.5-102.4 %. The limit of detection and limit of quantitation were 8.9 and 29.6 ng/g relative to the HPMC sample, or equivalent to 89 and 296 pg/g in the sample solution, respectively.
摘要：
由于其潜在的不利健康影响，药品中的一些N-亚硝胺受到严格管制，每日最大摄入量限制非常低。亚硝胺可以由亚硝酸盐和仲胺或叔胺的反应形成,当两种物质在药物合成或配制过程中共存时。减轻药物中亚硝胺风险的一个关键策略是选择含有低亚硝酸盐的药物赋形剂用于制剂。有必要开发一种灵敏的方法来测定药物赋形剂中的痕量亚硝酸盐，因为它使药物生产商能够研究亚硝胺的形成动力学并选择赋形剂供应商。本研究详细介绍了用于测定羟丙基甲基纤维素（HPMC）中痕量亚硝酸盐的二维离子色谱质谱（2D-IC/MS）方法的开发和验证，许多药物制剂中使用的最重要的药用辅料之一。2D-IC系统以心脏切割模式运行，浓缩器柱耦合两个维度。在第一维（1D）中使用标准孔阴离子交换柱，以实现大体积注入以提高灵敏度，并在亚硝酸盐和干扰氯化物峰之间提供改进的分辨率。在第二维（2D）中使用了具有不同选择性的高效微孔阴离子交换柱，以解析来自其他干扰物种的亚硝酸盐。使用2D-IC显著提高了分辨率,解决了由于离子抑制导致的灵敏度损失问题，否则一维分离。MS检测具有选择性离子监测和同位素标记的亚硝酸盐内标，进一步提高了方法的特异性，准确度,和坚固，与电导率检测相比。对于痕量测定，有一个干净的空白也是非常重要的。为此,开发了一种使用强阴离子洗涤的新型清洁程序，以去除实验室器皿中的亚硝酸盐污染。优化后的方法在18.5-5005.8ng/g的浓度范围内进行了线性验证，回归系数>0.9999，精密度RSD为3.5-10.1％，回收率为90.5-102.4％。相对于HPMC样品，检测限和定量限分别为8.9和29.6ng/g，或相当于样品溶液中的89和296pg/g，分别。
