Pesticides are essential in modern agricultural practices. Detection of pesticides is an essential step in regulating and monitoring the levels of pesticides in the environment. Even though GC/LC-MS is often the gold standard method for pesticide detection, recent technological advancements has promoted the creation of alternative techniques, such as Surface Enhanced Raman Spectroscopy (SERS), that provide added advantages such as ultrasensitive detection, 24 faster turnover, simpler protocols, in situ sampling, on-site capability and reduced cost. In this review, a comprehensive report of recent advances in SERS detection of synthetic chemical pesticides is given. The development and applications of the SERS technique for pesticide detection in both simple and complex matrices are discussed. The main advantages of using SERS for pesticide detection are highlighted, together with its limitations. Lastly, promising future trends and applications of SERS for pesticides detection are also discussed.

Understanding of the penetration behaviors of pesticides in fresh produce is of great significance for effectively applying pesticides and minimizing pesticide residues in food. There is lack, however, of an effective method that can measure pesticide penetration. Herein, we developed a novel method for real-time and in situ monitoring of pesticide penetration behaviors in spinach leaves based on surface-enhanced Raman scattering (SERS) mapping. Taking advantage of penetrative gold nanoparticles (AuNPs) as probes to enhance the internalized pesticide signals in situ, we have successfully obtained the internal signals from thiabendazole, a systemic pesticide, following its penetration into spinach leaves after removing surface pesticide residues. Comparatively, ferbam, a nonsystemic pesticide, did not show internal signals after removing surface pesticide residues, demonstrating its nonsystemic behavior. In both cases, if the surface pesticides were not removed, copenetration of both AuNPs and pesticides was observed. These results demonstrate a successful application of SERS as an effective method for measuring pesticides penetration in fresh produce in situ. The information obtained could provide useful guidance for effective and safe applications of pesticides on plants.

Removal of pesticide residues from fresh produce is important to reduce pesticide exposure to humans. This study investigated the effectiveness of commercial and homemade washing agents in the removal of surface and internalized pesticide residues from apples. Surface-enhanced Raman scattering (SERS) mapping and liquid chromatography tandem mass spectrometry (LC-MS/MS) methods were used to determine the effectiveness of different washing agents in removing pesticide residues. Surface pesticide residues were most effectively removed by sodium bicarbonate (baking soda, NaHCO) solution when compared to either tap water or Clorox bleach. Using a 10 mg/mL NaHCO washing solution, it took 12 and 15 min to completely remove thiabendazole or phosmet surface residues, respectively, following a 24 h exposure to these pesticides, which were applied at a concentration of 125 ng/cm. LC-MS/MS results showed, however, that 20% of applied thiabendazole and 4.4% of applied phosmet had penetrated into the apples following the 24 h exposure. Thiabendazole, a systemic pesticide, penetrated 4-fold deeper into the apple peel than did phosmet, a non-systemic pesticide, which led to more thiabendazole residues inside the apples, which could not be washed away using the NaHCO washing solution. This study gives us the information that the standard postharvest washing method using Clorox bleach solution for 2 min is not an effective means to completely remove pesticide residues on the surface of apples. The NaHCO method is more effective in removing surface pesticide residues on apples. In the presence of NaHCO, thiabendazole and phosmet can degrade, which assists the physical removal force of washing. However, the NaHCO method was not completely effective in removing residues that have penetrated into the apple peel. The overall effectiveness of the method to remove all pesticide residues diminished as pesticides penetrated deeper into the fruit. In practical application, washing apples with NaHCO solution can reduce pesticides mostly from the surface. Peeling is more effective to remove the penetrated pesticides; however, bioactive compounds in the peels will become lost too.

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Understanding pesticide penetration is important for effectively applying pesticides and in reducing pesticide exposures from food. This study aims to evaluate multiclass systemic and nonsystemic pesticide penetration in 3 representative fresh produce (apples, grapes, and spinach leaves). Surface-enhanced Raman scattering mapping was applied for in situ and real-time tracking of pesticide penetration over time. The results show that 100 mg/L of systemic pesticides, thiabendazole and acetamiprid, penetrated more rapidly and deeply with maximum depth around 220 μm after 48-h exposure into the tested fresh produce than 100 mg/L of nonsystemic pesticides, ferbam and phosmet, with maximum depth about 80 μm. The fact that 2 nonsystemic pesticides were also able to penetrate over time into all 3 fresh produce tested may raise additional food safety concerns. Comparatively, grapes were generally more resistant for pesticide penetration with all pesticides penetration depth below 80 μm compared to apples and spinach leaves. The information obtained here could provide technical support and guidance for accurate, effective, and safe application of pesticides and for the reduction of pesticide exposure from fresh produce.

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Adenosine plays a crucial role in the regulation of physiological activity in various tissues and organs. As adenosine is a possible biomarker for cancer, the determination of its level presents a demanding task for deeply monitoring progress of diseases. Through the synthesis of Fe3O4/Au/Ag nanocomposites weaved and stabilized by phytic acid and its salt, we develop a magnetically assisted surface-enhanced Raman scattering (SERS) protocol to determine trace level adenosine in urine samples from both lung cancer patients and health human. The magnetic properties of the nanocomposites enable to realize the simple separation of targeted molecules from a complex matrix and the Au/Ag nanoparticles moieties act as the SERS platform. This label-free Fe3O4/Au/Ag-nanocomposites-based SERS protocol shows a good stability, reproducibility, time efficiency (less than 20 min for one sample test), and huge sensitivity down to 1 × 10(-10) M. The protocol also has high selectivity because SERS signal of adenosine provides the molecular fingerprint information as well as an azo coupling pretreatment is performed to remove the interference of urea. Furthermore, a SERS array is designed for on-site screening adenosine in urine samples in a massive way using a portable Raman. Such a magnetically assisted SERS method as a powerful alternative can be expected as a smart and promising tool for effective assessment of healthcare.