PROFILING AGROCHEMICAL RESIDUES IN PRODUCE VIA PAPER CONE SPRAY IONIZATION AND PORTABLE INSTRUMENTATION

Publication Date

4-5-2019

Document Type

Poster

Degree Type

Undergraduate

Department

Chemistry

Mentor

Christopher Mulligan

Mentor Department

Chemistry

Abstract

Toxicants such as pesticides and herbicides can pose various health risks to consumers when frequently exposed to these agrochemicals. The use of agrochemicals to enhance crop yield leaves the potential of trace residues to be left on vegetation that is then later consumed by humans and livestock alike. Trace screening for known pesticides from consumed foodstuffs allows for the determination of said exposures, as well as validating compliance with "organic" produce standards. Here, we present paper cone spray ionization (PCSI) coupled with portable mass spectrometric (MS) instrumentation as a promising method that is both rapid and robust in this endeavor. Common and emerging agrochemicals of interest and both Certified Organic and non-organic fruits and vegetables were acquired from commercial sources. Home-built PCSI sources featured an outer layer of waxed weighing paper folded into a triangular pyramid, into which an inner cone of Whatman filter paper is placed; this inner cone serves as the bulk sample holder and spray solvent reservoir. This inner cone assembly serves to add on-board filtration of insoluble matrix. Preliminary testing was done on both commercial (Thermo LCQ Fleet ion trap MS) and portable (FLIR Systems AI-MS 1.2) MS instrumentation. Preliminary, proof-of-principle testing sought to establish the efficacy of extraction and sensitivity of PCSI featuring on-board filtration towards that analysis of common foodstuffs. Prior to analysis, food products were roughly ground (with skins, if applicable) and placed into the filter paper insert. A majority of the profiled agrochemicals were observed as protonated molecules, with some observed as sodiated, potassiated, and/or hydrated ions stemming from the complex matrices examined. For detection limit and quantitative assessments, organic produce was used as a standard matrix. Note that each organic candidate was thoroughly washed and examined pre-emptively via PCSI-MS to establish that no appreciable level of target pesticide was present. Known concentrations of target agrochemicals were added via dilute analytical standards to prepared food stuffs prior to analysis. Initial detection limits were determined to be in the low-to-high nanogram range, depending on analyte/foodstuff combination. Also presented in this work will be assessments of food-specific matrix effects and efficacy of filtration via the on-board filtration step.

This document is currently not available here.

Share

COinS