Automated single-ion peak fitting as an efficient approach for analyzing complex chromatographic data

Gabriel Isaacman-VanWertz; Donna T Sueper; Kenneth C Aikin; Brian M Lerner; Jessica B Gilman; Joost A de Gouw; Douglas R Worsnop; Allen H Goldstein

doi:10.1016/j.chroma.2017.11.005

Automated single-ion peak fitting as an efficient approach for analyzing complex chromatographic data

J Chromatogr A. 2017 Dec 22:1529:81-92. doi: 10.1016/j.chroma.2017.11.005. Epub 2017 Nov 7.

Authors

Gabriel Isaacman-VanWertz¹, Donna T Sueper², Kenneth C Aikin³, Brian M Lerner⁴, Jessica B Gilman³, Joost A de Gouw³, Douglas R Worsnop², Allen H Goldstein⁵

Affiliations

¹ Dept. of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, USA. Electronic address: ivw@vt.edu.
² Aerodyne Research, Inc., Billerica, MA, USA.
³ Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA.
⁴ Aerodyne Research, Inc., Billerica, MA, USA; Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA.
⁵ Dept. of Environmental Science, Policy, and Management, University of California, Berkeley, CA, USA; Dept. of Civil and Environmental Engineering, University of California, Berkeley, CA, USA.

PMID: 29126588
DOI: 10.1016/j.chroma.2017.11.005

Abstract

Chromatography provides important detail on the composition of environmental samples and their chemical processing. However, the complexity of these samples and their tendency to contain many structurally and chemically similar compounds frequently results in convoluted or poorly resolved data. Data reduction from raw chromatograms of complex environmental data into integrated peak areas consequently often requires substantial operator interaction. This difficulty has led to a bottleneck in analysis that increases analysis time, decreases data quality, and will worsen as advances in field-based instrumentation multiply the quantity and informational density of data produced. In this work, we develop and validate an automated approach to fitting chromatographic data within a target retention time window with a combination of multiple idealized peaks (Gaussian peaks either with or without an exponential decay component). We compare this single-ion peak fitting approach to drawn baseline integration methods of more than 70,000 peaks collected by field-based chromatographs spanning across a wide range of volatilities and functionalities. Accuracy of peak fitting under real-world conditions is found to be within 10%. The quantitative parameters describing the fit (e.g. coefficients, fit residuals, etc.) are found to provide valuable information to increase the efficiency of quality control and provide constraints to accurately integrate peaks that are significantly convoluted with neighboring peaks. Implementation of the peak fitting method is shown to yield accurate integration of peaks otherwise too poorly resolved to separate into individual compounds and improved quantitative metrics to determine the fidelity of the data reduction process, while substantially decreasing the time spent by operators on data reduction.

Keywords: Chemometrics; Data reduction; Environmental chemistry; Gas chromatography; Peak fitting; Peak integration.

Publication types

Validation Study

MeSH terms

Chromatography*
Reproducibility of Results
Statistics as Topic / methods*
Statistics as Topic / standards