Rapid Detection of Malathion, Phoxim and Thiram on Orange Surfaces Using Ag Nanoparticle Modified PDMS as Surface-Enhanced Raman Spectroscopy Substrate

Abstract

Malathion, phoxim, and thiram are organophosphates and organosulfur pesticides widely used in agricultural products. The residues of these pesticides present a direct threat to human health. Rapid and on-site detection is critical for minimizing such risks. In this work, a simple approach was introduced using a flexible surface-enhanced Raman spectroscopy (SERS) substrate. The prepared Ag nanoparticles-polydimethylsiloxane (AgNPs-PDMS) substrate showed high SERS activity, good precision (relative standard deviation = 5.33%), and stability (30 days) after optimization. For target pesticides, the linear relationship between characteristic SERS bands and concentrations were achieved in the range of 10~1000, 100~5000, and 50~5000 μg L−1 with LODs down to 3.62, 41.46, and 15.69 μg L−1 for thiram, malathion, and phoxim, respectively. Moreover, SERS spectra of mixed samples indicated that three pesticides can be identified simultaneously, with recovery rates between 96.5 ± 3.3% and 118.9 ± 2.4%, thus providing an ideal platform for detecting more than one target. Pesticide residues on orange surfaces can be simply determined through swabbing with the flexible substrate before acquiring the SERS signal. This study demonstrated that the prepared substrate can be used for the rapid detection of pesticides on real samples. Overall, this method greatly simplified the pre-treatment procedure, thus serving as a promising analytical tool for rapid and nondestructive screening of malathion, phoxim, and thiram on various agricultural products.

Constructing graphene oxide/Au nanoparticle cellulose membranes for SERS detection of mixed pesticide residues in edible chrysanthemum

“…S4†) and comparing with literature reports. 13,33,35 In detail, for fenthion, the strong SERS bands at 1058 and 1229 cm −1 were assigned to the stretching vibration of the aromatic ring and the asymmetric stretching vibration of the P–O–Ar bond, respectively. As for phoxim, strong SERS enhancement was observed at 769, 1009 and 1508 cm −1 , which can be attributed to the stretching vibration of the PS double bond, the in-plane bending of the C–H bond and the stretching vibration of the aromatic ring, respectively.…”

“…30 So far, different forms of SERS substrates have been prepared for the sensitive detection of various pesticides, including screen-printed paper-based SERS swabs, 31 metal–organic framework-coated Au gratings, 32 Au NP-coated stainless-steel wires, 33 Ag NPs@paper swab 34 and Ag NP-coated polydimethylsiloxane. 35,36 These studies demonstrated the feasibility of employing SERS for the rapid and sensitive detection of pesticide residues in food. However, a SERS-based method for detecting pesticides in edible chrysanthemum has yet to be reported.…”

Surface-enhanced Raman scattering detection of thiram and ciprofloxacin using chitosan–silver coated paper substrates

“…The enhancement factor (EF) for detecting thiram (0.1 μM) using the Ag/CH substrate was calculated using the equation: 29,32,37 EF = ( I SERS × N bulk )/( I bulk × N SERS )where I SERS and I bulk are the peak intensities at 1376 cm −1 from the SERS and conventional Raman spectra of thiram, respectively. N bulk and N SERS represent the estimated number of analyte molecules probed for a bulk sample (thiram powder) and the Ag/CH substrate, respectively.…”

“…Therefore, exposure to these chemicals through the consumption of contaminated water can lead to severe health problems. 29,30 Thus, monitoring the levels of these contaminants in the water is very important as a preventive measure to protect public health and the environment.…”

“…The enhancement factor (EF) for detecting thiram (0.1 µM) using the Ag/CH substrate was calculated using the equation: 29,32,37…”