The solid-phase microextraction technique quantifies analytes without considerably affecting the sample composition. Herein, a proof-of-concept study was conducted to demonstrate the use of coated probe electrospray ionization (coated-PESI) and coated blade spray (CBS) as ambient mass spectrometry approaches for monitoring drug biotransformation. The ability of these methods was investigated for monitoring the dephosphorylation of a prodrug, combretastatin A4 phosphate (CA4P), into its active form, combretastatin A4 (CA4), in a cell culture medium supplemented with fetal bovine serum. The CBS spot analysis was modified to achieve the same extraction efficiency as protein precipitation and obtained results in 7 min. Because coated-PESI performs extraction without consuming any samples, it is the preferred technique in the case of a limited sample volume. Although coated-PESI only extracts small quantities of analytes, it uses the desorption solvent volume of 5–10 pL, resulting in high sensitivity, thus allowing the detection of compounds after only 1 min of extraction. The biotransformation of CA4P into CA4 via phosphatases occurs within the simple matrix, and the proposed sample preparation techniques are suitable for monitoring the biotransformation.

固相微萃取技术可对分析物进行定量，而不会显着影响样品成分。在此，进行了一项概念验证研究，以证明使用涂层探针电喷雾电离（涂层-PESI）和涂层刀片喷雾（CBS）作为监测药物生物转化的环境质谱方法。研究了这些方法在补充有胎牛血清的细胞培养基中监测前药考布他汀 A4 磷酸盐 (CA4P) 去磷酸化为其活性形式考布他汀 A4 (CA4) 的能力。对 CBS 斑点分析进行修改，以达到与蛋白质沉淀相同的提取效率，并在 7 分钟内获得结果。由于涂层 PESI 无需消耗任何样品即可进行提取，因此在样品量有限的情况下，它是首选技术。虽然涂层 PESI 仅提取少量分析物，但它使用 5-10 pL 的解吸溶剂体积，因此具有高灵敏度，因此只需提取 1 分钟即可检测化合物。CA4P 通过磷酸酶生物转化为 CA4 发生在简单的基质内，所提出的样品制备技术适合监测生物转化。