摘要:
为了进一步提高大表面样品的分析速度,减少给定样品表面的扫描次数,建立了一种单次扫描即可检测分布于大表面样品上任意位置痕量待测物的质谱分析方法.以人造革表面(4 cm×4 cm)添加的赖氨酸和黑索今为代表性检测对象,用一块无毛刺等边三角形金属铜电极(边长为8.6 cm)紧贴在样品表面,将甲醇-水(3∶7,V/V)电离试剂涂洒在金属电极表面,让其与样品表面保持湿润接触,并使三角形电极尖端对准质谱仪的离子入口;然后在金属电极上施加+5.8 kV高压,在电场的驱动下,湿润表面的待测物朝着质谱入口移动,并在三角形电极尖端形成待测物离子进入质谱仪检测.结果表明,该方法可单次扫描检测随机分布在皮革样品表面上任意位置的非均匀分布的赖氨酸和黑索今,检测限可达6.2×10-7 μg/cm2,分析单个样品表面的时间不到2 s;与采用电喷雾解吸电离质谱等顺次扫描检测(采样面积不到1 mm2)的方法相比,本方法的分析速度提高了1 000倍.
Abstract:
Ambient ionization mass spectrometry has significantly improved the efficiency of analysis complex matrix sample due to its high sensitivity,selectivity and throughput.At present,direct ionization sources coupled with mass spectrometer including desorption electrospray ionization (DESI),real time online (DART),matrix assisted laser desorption ionization (MALDI),laser ablation electrospray ionization (LAESI),desorption atmospheric pressure chemical ionization (DAPCI),extractive electrospray ionization (EESI) etc.are applied for the direct ionization targeting molecular followed by mass spectrometer characterization.A famous ionization technique namely DESI is the most representative ambient source,which can ionization the polar compounds with bulk solid surface focused on a large number of studies on the detection methods of explosives.However,DESI in the ionization of solid explosives is needed continuous scanning and a single sampling area can not exceeding 1 cm2,resulting in timeconsuming and inaccurate enough results.In order to further improve the analysis rate of the large surface sample and decrease the number of scanning for a given sample surface,a novel mass spectrometry method with a single scan was established for detecting trace substance distributed in large sample surface of any position.Using artificial leather surface (length of a side:4 cm×4 cm) added lysine and royal demolition explosive (RDX) as representative detection object,the triangular metal copper electrode (length of a side:8.6 cm) which was applied the ionization regent with methanol-water (3 ∶ 7,V/V) was closed to the sample surface,making the tip of the triangle metal copper electrode on the mass spectrometer entrance.The trace substance form into ions in triangle electrode tip towards mass spectrometry when applying +5.8 kV high voltage on the metal copper electrode.This experimental results show that the novel method with a single scan can detect randomly and non-uniform distributed on the surface of the leather sample of lysine and/or RDX at any position,providing the speed for a single sample analysis within 2 s,the limit of detection (LOD) of 6.2 × 10-7μg/cm2.compared with analyzing speeding on desorption electrospray ionization mass spectrometry (single sampling area less than 1 cm2),the analyzing speed of the established method is 1 000 times than DESI.Overall,this method can provide a promising analytical tool for advanced studies on monitoring of trace explosive,the identification of the food quality and the products in the import and export trade,and the pharmacokinetics of drug metabolism in vivo.
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