Molnár Borbála, Fodor Blanka, Boldizsár Imre, Molnár-Perl Ibolya
Institutes of Chemistry, Departments of Analytical Chemistry, L. Eötvös University, Pázmány Péter sétány 1/A-C, Budapest 1117, Hungary; Doctoral School of Pharmaceutical Sciences, Semmelweis University, Üllői út 26, Budapest 1085, Hungary.
Institutes of Chemistry, Departments of Analytical Chemistry, L. Eötvös University, Pázmány Péter sétány 1/A-C, Budapest 1117, Hungary.
J Chromatogr A. 2016 Apr 1;1440:172-178. doi: 10.1016/j.chroma.2016.02.044. Epub 2016 Feb 20.
A literature criticism is given on methods using currently gas chromatography mass spectrometry (GC/MS) to determine cathine (CAT), cathinone (CTN) and norephedrine (NE), jointly khatamines. In this study, khatamines' oximation, trimethylsilylation and mass fragmentation properties-applying N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA), its trimethyliodosilane (TMIS) catalyst containing version (MSTFA(TMIS)), N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and hexamethyldisilazane (HMDS)-was highlighted, at first. Derivatization, mass fragmentation and quantitation related, optimized model investigations have been carried out as a function of the reaction times and conditions. Special emphasis was put (i) on the stability of the primarily formed (CAT-2TMS, NE-2TMS, CTN-TMS(TMS-oximes)1,2), then transformed, fully derived (CAT-3TMS, NE-3MTS, CTN-2TMS(TMS-oximes)1,2) species, and, (ii) on the proportionally formed stable products, suitable to selective quantitation of all three natural amines, simultaneously. Results, as novelty to the field confirmed that (i) TMIS catalyzed trimethylsilyation triggers to form fully derivatized species unfortunately, in part only; while, (ii) khatamines' simultaneous quantitation needs to be carried out in a two steps derivatization process consisting of oximation (1st step, hydroxylamine in pyridine) and trimethylsilylation (2nd step, MSTFA), to the CAT-2TMS, NE-2TMS, CTN-TMS(TMS-oximes)1,2. These species were characterized with their retention, mass fragmentation and analytical performance properties, in model solutions and in the presence of plant tissues, as well: R(2), limit of quantitation (LOQ) data, expressed in pg/1μL injection basis, proved to be 62.5pg (CAT), 20pg (NE) and 62.5pg (CTN), respectively. The practical utility of proposal was enormously enhanced by the novel, direct sample preparation method. In this process, the freshly harvested, freeze-dried, then pulverized leaves of Catha edulis FORKS were directly derivatized, in the presence of the matrix. Reproducibility (in average 2.07 RSD% varying between 0.15 and 5.5 RSD%), linearity (0.9990-0.9994) and recovery (95.7-99.1%) values of the new sample preparation protocol was confirmed by the standard addition method for CAT, NE and CTN equally. From plant leaf, 0.061w/w% CAT and 0.014w/w% NE contents were obtained. In this tissue CTN was not found. Very likely attributable to the unfavorable climate for the plant: grown in Hungary of temperate zone and naturalized in the tropical Africa.
对目前使用气相色谱 - 质谱联用（GC/MS）测定去甲伪麻黄碱（CAT）、卡西酮（CTN）和去甲麻黄碱（NE）（统称为巧茶碱）的方法进行了文献批评。在本研究中，首先突出了巧茶碱的肟化、三甲基硅烷化和质量碎片化性质，应用了N - 甲基 - N - （三甲基硅基）三氟乙酰胺（MSTFA）、其含三甲基碘硅烷（TMIS）催化剂的版本（MSTFA(TMIS)）、N，O - 双（三甲基硅基）三氟乙酰胺（BSTFA）和六甲基二硅氮烷（HMDS）。进行了与衍生化、质量碎片化和定量相关的优化模型研究，作为反应时间和条件的函数。特别强调了：（i）首先形成的（CAT - 2TMS、NE - 2TMS、CTN - TMS(TMS - 肟)1,2）的稳定性，然后转化为完全衍生的（CAT - 3TMS、NE - 3MTS、CTN - 2TMS(TMS - 肟)1,2）物种；以及（ii）比例形成的稳定产物，适用于同时选择性定量所有三种天然胺。该领域的新结果证实：（i）TMIS催化的三甲基硅烷化不幸仅部分触发形成完全衍生的物种；而（ii）巧茶碱的同时定量需要在由肟化（第一步，吡啶中的羟胺）和三甲基硅烷化（第二步，MSTFA）组成的两步衍生化过程中进行，以得到CAT - 2TMS、NE - 2TMS、CTN - TMS(TMS - 肟)1,2。这些物种在模型溶液和植物组织存在的情况下，也通过其保留、质量碎片化和分析性能特性进行了表征：以pg/1μL进样为基础表示的R(2)、定量限（LOQ）数据分别证明为62.5pg（CAT）、20pg（NE）和62.5pg（CTN）。新的直接样品制备方法极大地提高了该提议的实际效用。在这个过程中，新鲜收获、冷冻干燥然后粉碎的巧茶（Catha edulis FORKS）叶片在基质存在下直接进行衍生化。通过标准加入法对CAT、NE和CTN同样证实了新样品制备方案的重现性（平均2.07 RSD%，在0.15至5.5 RSD%之间变化）、线性（0.9990 - 0.9994）和回收率（95.7 - 99.1%）值。从植物叶片中获得了0.061w/w%的CAT和0.014w/w%的NE含量。在该组织中未发现CTN。这很可能归因于对该植物不利的气候：生长在温带的匈牙利并在热带非洲归化。
