In this study, a novel method for the direct coupling of metal probe microextraction (MPME) and a dielectric barrier discharge ionization (DBDI) source with mass spectrometry (MS) is reported. Analytes adsorbed on a tungsten needle were directly transferred to the DBDI source via rapid thermal desorption, which resulted in a limit of detection as low as 8 pg/mL. This is in part due to the "active capillary" configuration of the plasma ion source, where the efficiency of ion transfer to the MS is ∼100%. Specialty gases to maintain the plasma and carry analytes to the MS are not required. In contrast to direct one-step ionization of molecular adsorbates, the complete separation of the analyte desorption from the probe and the ionization event in our experimental setup greatly enhanced the sensitivity and detection reproducibility (RSD of 8.3%). We show detection of pyrimethamine, a first-line drug for the treatment and prevention of Plasmodium falciparum malaria all over the world, by this MPME/DBDI/MS method. The detection of drug residues in live fish and paramecium was achieved without the need for any sample pretreatment. The relative concentration of the drug in different organs of the fish was determined. This simple and convenient method has the potential for the analysis of chemicals even in single-cell organisms.

中文翻译：

---

金属探针微萃取与介电阻挡层放电电离质谱联用，用于检测生物体中的药物残留。

在这项研究中，报道了一种通过质谱法（MS）直接耦合金属探针微萃取（MPME）和电介质势垒放电电离（DBDI）源的新方法。吸附在钨针上的分析物通过快速热脱附直接转移到DBDI源，导致检测限低至8 pg / mL。这部分是由于等离子体离子源的“主动毛细管”配置，其中离子转移到MS的效率约为100％。不需要用于维持血浆并将分析物携带到MS的特殊气体。与分子吸附物的直接一步电离相反，在我们的实验装置中将分析物从探针脱附的完全分离和电离事件大大提高了灵敏度和检测重现性（RSD为8。3％）。我们通过这种MPME / DBDI / MS方法显示了乙胺嘧啶的检测，乙胺嘧啶是治疗和预防恶性疟原虫疟疾的一线药物。无需任何样品预处理即可检测活鱼和草履虫中的药物残留。测定了鱼在不同器官中的相对浓度。这种简单方便的方法即使在单细胞生物中也具有分析化学物的潜力。确定了鱼在不同器官中的相对浓度。这种简单方便的方法即使在单细胞生物中也具有分析化学物的潜力。确定了鱼在不同器官中的相对浓度。这种简单方便的方法甚至在单细胞生物中也具有分析化学物的潜力。