Mass Spectrometry Center, Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
Anal Chem. 2009 Dec 15;81(24):10080-8. doi: 10.1021/ac901122b.
A transient microenvironment mechanism (TMEM) is proposed to address matrix effects for direct analysis in real time (DART). When the DART gas stream is in contact with the sample, a transient microenvironment (TME), which can shield analytes from direct ionization, may be generated through the desorption of the matrix containing the analyte. The DART gas stream can directly ionize the matrix molecules, but the analytes will be ionized primarily through gas-phase ion/molecule reactions with the matrix ions. Experimental results showed that as little as 10 nL of liquid or 10 microg of solid was able to generate an efficient TME. Generated TMEs were able to control the ionization of an analyte below an analyte-to-matrix ratio that was dependent on the DART temperature and the boiling points of the analyte and matrix. TMEs generated by common solvents were studied in detail. The ionization of both polar and nonpolar compounds, present in a solvent or another analyte below a ratio of 1:100, were found to be mainly controlled by the generated TMEs at a DART temperature of 300 degrees C.
提出瞬态微环境机制（TMEM）以解决直接实时分析（DART）中的基质效应。当 DART 气流与样品接触时，通过含有分析物的基质的解吸，可能会产生瞬态微环境（TME），该微环境可以保护分析物免受直接电离。DART 气流可以直接电离基质分子，但分析物主要通过气相离子/分子与基质离子的反应进行电离。实验结果表明，只需 10 nL 的液体或 10 μg 的固体即可产生有效的 TME。生成的 TME 能够控制分析物的电离，其分析物与基质的比例取决于 DART 温度以及分析物和基质的沸点。详细研究了由常见溶剂产生的 TME。在 DART 温度为 300°C 时，发现溶剂或另一种分析物中存在的极性和非极性化合物的电离主要受生成的 TME 控制，其比例为 1:100 或更低。
