The ECHO technique--the more effective way of data evaluation in liquid chromatography-tandem mass spectrometry analysis.

The aim of this study was to evaluate the applicability of ECHO technique in pesticide residue analysis using LC/MS/MS instruments with atmospheric pressure chemical (APCI) and electrospray (ESI) ionization. The technique is based on simultaneous injections of reference standards and samples in one run. First and second injections are made ahead and behind a precolumn, respectively, thus resulting in a short difference of retention times between standard and sample peak.