Detection of Methomyl, a Carbamate Insecticide, in Food Matrices Using Terahertz Time-Domain Spectroscopy

Seung Hyun Baek, Ju Hee Kang, Yeun Hee Hwang, Kang Min Ok, Kyungwon Kwak, Hyang Sook Chun

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)

Abstract

The aim of this study was to investigate the feasibility of detecting methomyl, a carbamate insecticide, in food matrices (wheat and rice flours) using terahertz time-domain spectroscopy (THz-TDS). In the frequency range 0.1–3 THz, the characteristic THz absorption peaks of methomyl at room temperature were detected at 1 (33.4 cm−1), 1.64 (54.7 cm−1), and 1.89 (63.0 cm−1) THz. For detailed spectral analysis, the vibrational frequency and intensity of methomyl were calculated using solid-state density functional theory to mimic molecular interactions in the solid state. Qualitatively, the simulated spectrum was in good agreement with the experimental spectrum. Analysis of the individual absorption modes revealed that all of the features in the THz spectrum of methomyl were mainly generated from intermolecular vibrations. The peak appearing at 1 THz (33.4 cm−1) was then selected and tested for its suitability as a fingerprint for detecting methomyl in food matrices. Its absorbance was dose-dependently distinguishable from that of wheat and rice flours. The calibration curve of methomyl had a regression coefficient of >0.974 and a detection limit of <3.74 %. Accuracy and precision expressed as recovery and relative standard deviation in interday repeatability were in the ranges 78.0–96.5 and 2.83–4.98 %, respectively. Our results suggest that THz-TDS can be used for the rapid detection of methomyl in foods, but its sensitivity needs to be improved.

Original languageEnglish
Pages (from-to)486-497
Number of pages12
JournalJournal of Infrared, Millimeter, and Terahertz Waves
Volume37
Issue number5
DOIs
Publication statusPublished - 2016 May 1
Externally publishedYes

Keywords

  • Detection
  • Methomyl
  • Solid-state density functional theory
  • Terahertz time-domain spectroscopy
  • Wheat and rice flours

ASJC Scopus subject areas

  • Radiation
  • Instrumentation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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