Wu Chunping, Ifa Demian R, Manicke Nicholas E, Cooks R Graham
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
Anal Chem. 2009 Sep 15;81(18):7618-24. doi: 10.1021/ac901003u.
Direct and rapid analysis of cholesterol was accomplished in the ambient environment using reactive desorption electrospray ionization (DESI) mass spectrometry. This was achieved by electrospraying reagent solutions in the form of high velocity charged droplets at surfaces such as dried serum samples and animal tissue sections. Betaine aldehyde, incorporated into the spray solvent, reacts selectively and rapidly with the alcohol group of cholesterol by nucleophilic addition, forming a hemiacetal salt. Limits of detection for pure cholesterol and related compounds were approximately 1 ng when a solution of cholesterol of 1 microg/mL was spotted onto the surface. Quantitative analysis of free cholesterol in serum using reactive DESI was demonstrated using cholesterol-d7 as internal standard. High throughput analysis of small volumes of serum spotted onto a suitable substrate was achieved at an analysis rate of approximately 14 s per sample, with a relative standard deviation (RSD) of ca. 6%. Use of reactive DESI in the imaging mode allowed 2D spatial distributions of phospholipids and cholesterol to be recorded simultaneously in rat brain tissues.
利用反应性解吸电喷雾电离（DESI）质谱在环境条件下实现了胆固醇的直接快速分析。通过将试剂溶液以高速带电液滴的形式电喷雾到干燥血清样本和动物组织切片等表面来实现这一点。掺入喷雾溶剂中的甜菜碱醛通过亲核加成与胆固醇的醇基选择性快速反应，形成半缩醛盐。当将1μg/mL的胆固醇溶液点样到表面时，纯胆固醇及相关化合物的检测限约为1ng。以胆固醇-d7作为内标，证明了使用反应性DESI对血清中的游离胆固醇进行定量分析。以约14秒/样本的分析速率实现了对点样在合适底物上的少量血清的高通量分析，相对标准偏差（RSD）约为6%。在成像模式下使用反应性DESI能够同时记录大鼠脑组织中磷脂和胆固醇的二维空间分布。
