Anal Chem. 2010 Feb 15;82(4):1179-82. doi: 10.1021/ac902277d.
Accurate and rapid quantitation is advantageous to identify counterfeit and substandard pharmaceutical drugs. A standard-free electrospray ionization mass spectrometry method is used to directly determine the dosage in the prescription and over-the-counter drugs Tamiflu, Sudafed, and Dramamine. A tablet of each drug was dissolved in aqueous solution, filtered, and introduced into solutions containing a known concentration of l-tryptophan, l-phenylalanine, or prednisone as a clustering agent. The active ingredient(s) incorporates statistically into large clusters of the clustering agent where effects of differential ionization/detection are substantially reduced. From the abundances of large clusters, the dosages of the active ingredients in each of the tablets were determined to typically better than 20% accuracy even when the ionization/detection efficiency of the individual components differed by over 100x. Although this unorthodox method for quantitation is not as accurate as using conventional standards, it has the advantages that it is fast, it can be applied to mixtures where the identities of the analytes are unknown, and it can be used when suitable standards may not be readily available, such as schedule I or II controlled substances or new designer drugs that have not previously been identified.
准确快速的定量分析有利于识别假冒伪劣药品。本研究采用无标准电喷雾电离质谱法直接测定处方和非处方药达菲、速达菲和晕车灵中的剂量。将每种药物的一片溶解于水溶液中，过滤后加入含有已知浓度 l-色氨酸、l-苯丙氨酸或强的松作为聚类剂的溶液中。活性成分（s）以统计学方式整合到聚类剂的大簇中，从而大大降低了差分电离/检测的影响。从大簇的丰度中，可以确定每个片剂中活性成分的剂量，通常准确度优于 20%，即使个别成分的电离/检测效率相差超过 100 倍。虽然这种非常规的定量方法不如使用常规标准准确，但它具有快速、可应用于分析物身份未知的混合物以及在合适的标准可能不易获得的情况下（如附表 I 或 II 管制物质或以前未识别的新型设计药物）的优点。
