Utility of the summation chromatographic peak integration function to avoid manual reintegrations in the analysis of targeted analytes

Authors: Lehotay, Steven

Submitted to: LC GC North America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2017
Publication Date: 6/1/2017
Citation: Lehotay, S.J. 2017. Utility of the summation chromatographic peak integration function to avoid manual reintegrations in the analysis of targeted analytes. LC GC North America. 35:391-402.

Interpretive Summary: As analytical technologies and techniques have improved, sample throughput in chromatography has become limited by data processing of large generated data sets. Human review and manual corrections of integrated chromatographic peaks has been standard practice for decades, but this is no longer possible in high-throughput applications involving many targeted chemicals. A novel application of a simple automated summation integration approach was empirically evaluated in this study entailing pesticide residue monitoring. The main conclusion was that peak height results gave significantly lower limits of quantification and identification than peak area results, which is important for chromatographic applications in many fields of investigation. This simple, reliable, and automatic data handling approach for chromatography is expected to be widely implemented.

Technical Abstract: As sample preparation and analytical techniques have improved, data handling has become the main limitation in automated high-throughput analysis of targeted chemicals in many applications. Conventional chromatographic peak integration functions rely on complex software and settings, but untrustworthy integrations still routinely lead to time-consuming manual review and re-integrations. Current rugged GC– and LC– MS/MS methods typically only need mg or ug amounts of equivalent injected sample to achieve <10 ng/g limits of quantification (LOQ) and identification (LOI), while also yielding very consistent retention times (tR) and peak widths. This reliability permits use of the summation peak integration function, which simply draws a baseline from preset start and stop times and records the signal (or noise) above that line. Then, analyte identification is made automatically via post-run data processing by taking defined criteria into account (e.g. signals > LOQ in the correct ion ratios). In this study, an empirical assessment of summation integration (using the lowest baseline point in user-defined tR windows) was conducted involving 490 low-pressure GC-MS/MS analyses of 70 pesticides in 10 common fruits and vegetables over the course of 10 days. In an additional enhancement to the many other benefits in this overall approach, peak heights were found to give significantly lower LOQs, LOIs, and fewer false negatives for more pesticides and matrices than peak areas.