A REVIEW OF RAPID PESTICIDE RESIDUES DETERMINATION IN VEGETABLES AND FRUITS

, chromatography-mass spectrometry, etc. These methods have been widely used in pesticide residue detection, and a series of important achievements have been made. Although with high detection sensitivity, these methods have some problems such as complicated sample pretreatment, expensive equipment, time-consuming analysis, and the need for specialized instrument operators and so on, which cannot meet the requirements of rapid and real-time field detection of pesticide residues. Therefore, researchers in various fields have carried out and strengthened the research on rapid detection technology of pesticide residues, seeking to develop convenient, sensitive, accurate and stable new pesticide residue detection technology. In this paper, we mainly reviewed the rapid detection technologies of pesticide in fresh fruits and vegetables in recent years, including new chromatographic analysis, enzyme inhibition, fluorescence sensor, spectrophotometric and biosensor detection technology, and analyzed the development status, advantages, and disadvantages of each method, as well as the development prospect of rapid detection technology in the future.

Introduction.Modern agricultural production is inseparable from the usage of pesticides to prevent and control all kinds of crop diseases, insect pests and weeds, following by severe food safety problems due to pesticide residues (Caria et al., 2021; Loganathan & Murugan, 2017).There are many kinds of pesticide, including organophosphorus pesticides, organic nitrogen pesticides (carbamate, triazine and its derivatives).Among them, organophosphorus and organic nitrogen pesticides have occupied the vast majority of the market because of their short halflife in the environment, relatively low toxicity to mammals, wide range of application and low price.As is known to all, residual pesticides are toxic, which can cause various chronic or acute poisoning, leading to physiological diseases such as rashes, asthma, chronic diseases, and neurological diseases (Calaf et al., 2021; Freire & Koifman, 2012; Li et al., 2021;Steenland et al., 1994;Upadhayay et al., 2020;Yu et al., 2021).Therefore, to ensure the quality and safety of agricultural products, efficient and rapid pesticide residue detection methods are researched (Wu et al., 2021).Traditional detection methods include chromatography, chromatography-tandem mass spectrometry and highperformance liquid chromatography and so on (Golge, 2021).They can be the preferred detection methods in the formulation of national standards for pesticide detection in many countries because of the high repeatability and stable test results.However, these methods need large detection equipment and specific operating environment, which are not suitable for the practical production requirements for the rapid field test.
In recent decades, a variety of low time-consuming, convenient and rapid detection methods developed, including but not limited to new chromatographic analysis, enzyme inhibition, fluorescence sensor, spectrophotometric and biosensor detection technology (Ninga et al., 2021;Rojas et al., 2021;Saegusa et al., 2021).What's more, these technologies have made great breakthroughs on the basis of each one, and various rapid detection technologies tend to be more and more cross-fusion, mutual penetration and advantages superposition (Hao & Wang, 2016) Although their disadvantage like expensive equipment requirement, high technical personnel, complex pretreatment and testing time, cross-fusion of rapid detection technologies make these methods showing great potential in the market for rapid detection recently.Khan (Khan et al., 2018) proposed a pressurized liquid extraction by ethyl acetate based method for simultaneous analysis of different pesticide residues in tuber crops, and then selectively identified and quantified the residuals by GC-MS selected reaction monitoring.They got the limits of quantification with 0.1-10 ng/g, and recovery rate from 70 % to 120 %.
Chromatographic detection technique is mainly used in laboratory precision detection.This technology shows high selectivity for organophosphorus pesticides, but its scope of action is relatively limited.The current research directions are mostly focused on improving pretreatment technology, enrichment methods and extraction methods.In other aspects, the method for rapid detection in the market needs to be further improved.

Enzyme inhibition detection techniques
Enzyme inhibition rapid detection method is based on the inhibitory effect of pesticide residues in food on enzyme.This technology has the advantages of simple and quick operation and simple pretreatment, and a variety of simple instruments have been developed for rapid detection in the market currently.However, this method has great limitations, and with poor stability due to many factors to be controlled (Gumpu et al., 2017;Li et al., 2019).So, there are a large room for improvement in sensitivity and accuracy.Through the effective combination with the biosensor technology, the sensitivity and accuracy of the enzyme inhibition technology have been greatly improved.After the fusion, the enzyme inhibition method with the biosensor technology is more suitable for rapid detection (Badawy, 2021; Singh et al., 2020).The rapid detection principle of enzyme inhibition method is relatively simple.By organophosphorus pesticides inhibiting the activity of acetylcholinesterase, the catalytic process can produce less H2O2, and the oxidation ability can be reduced, resulting in visible discoloration reaction of the substrate (Albendin et al., 2021;Lin et al., 2021).The intensity of colorimetric signal is an important factor in the research of enzyme inhibition method to realize the real visual detection.Yang (Yang et al., 2019) proposed an enzyme inhibition method to detect the pesticide residues of the milk.He established a system to study the inhibitory reactions of organic phosphorus and aminoformate residues in milk.The analysis of color reactions of milk showed a good correlation between color intensity and content of tolclofos-methyl, methamidophos and isoprocarb 1-naphthalenyl methyl carbamate, and the detection range of four kinds of pesticides is 0.5 ~ 1.0 mg/kg.
By combining with the biological sensing technology, the application scope of the enzyme inhibition method is expanded, and the enzyme sensitivity is enhanced.Enzyme inhibition sensor is one of the most widely used rapid detection technique in the current rapid detection market, but there are still many problems with its own (Wu et al., 2019).Recently, many researchers study the selective purification of enzyme, effective oxidation pretreatment, colorimetric signal enhancement and false positives elimination.The sensitivity of enzyme inhibition method is influenced by the purity of the enzyme, the concentration of substrate and environmental factors, etc., and the stability and sensitivity of the enzyme suppression method are need to be higher  (Zhou et al., 2018).Carbon Quantum Dots (CQDs) have been proposed as the photo-sensitizer for this purpose, however the optical properties of pure CQDs restrict the detection limit of such an approach.Doping is an effective strategy to introduce novel electronic structure into the CQDs to solve this problem.using ionic liquids as a single source, H. Li (Li et al., 2016) proposed a novel N and S co-doped CQDs by a simple ultrasonic method.The doping in the structure introduces localized states which can trap photo-excited electrons and enhance their PL lifetime.These quantum dots are successfully used as the basis of a simple, efficient sensor for ultrasensitive pesticide detection (Limit of Detection = 5 ppb).J. Hou (Hou et al., 2015) used tyrosinase to catalyze the oxidation of tyrosine methyl ester on the surface of carbon dots to corresponding quinone products, which can quench the fluorescence of carbon dots, and the enzyme inhibition rate is proportional to the logarithm of the methyl parathion concentration in the range 1.0×10−10-1.0×10−4M with the detection limit (S/N = 3) of 4.8×10−11 M.
The combination of fluorescence detection method and biosensor method has greatly promoted the rapid detection of pesticide residues (Hou et  .By reducing the silver nitrate solution in the presence of Diospyros blancoi leaf infusion, and then mixing with the l-cysteine solution, the colorimetric sensor was prepared.In the presence of cypermethrin, the color of l-cys-agnps was obvious, and the peak absorbance decreased from 1.15 to 0.17.The optical colorimetric sensor synthesized from gold nanoparticles has high sensitivity (Li, et al., 2018).Moreover, the gold nanoparticles are stable, and the reaction with pesticides can make the gold nanoparticles aggregate and produce visible color changes (Bettazzi et Shen et al., 2021).The large specific surface area and easy modification characteristics of nanomaterials provide more active sites on the electrode surface, which is more conducive to full contact with the reactants, thus providing detectable electrical signals.Zhao (Zhao et al., 2015) constructed an ultra-sensitive current sensor by using Au nanoparticles (AuNPs)β-cyclodextrin (β-CD) and Prussian blue-chitosan (PB-CS) and acetylcholinesterase(AChE), and realized the high sensitivity detection of malathion and carbaryl through the synergic action of multiple components, with detection limit as low as 4.14 pg/mL and 1.15 pg/mL, respectively.By cross-linking acetylcholinesterase onto the IL-GR/Co3O4 / CHI electrode constructed from ionic liquid modified graphene (IL-GR) and Co3O4 nanoparticles, Y. Zheng (Zheng et al., 2016) was able to effectively reduce the loss of enzyme activity and improve the detection sensitivity.A linear relationship between the inhibition percentage (I%) and logarithm of the concentration of dimethoate was found in the range from 5.0 × 10−12 to 1.0 × 10−7 M, with a detection limit of 1.0 × 10−13 M (S/N = 3).
In order to further enhance the stability of the biosensors, a nanocomposite material which can significantly enhance the mechanical strength of each component is formed by introducing a polymer into the nanometer material (Bagheri et Zheng et al., 2015).New biosensors have developed rapidly, and the stability and sensitivity of all kinds of biosensors have been greatly improved, but they are only used for single pesticide and the detection range still is very small.So, they can't be widely used for the rapid detection of a variety of organophosphorus pesticides on the market.The development of nanometer materials made great progress for biological sensor technology in sensitivity and stability, which has significantly outpaced the development of other rapid detection technologies (Jiang et al., 2020;Wang et al., 2016).Therefore, the cross-fusion detection methods combining with biosensor and other rapid detection technologies retain the development advantages, and overcome many limiting factors in the rapid detection technology, making the rapid detection technology develop rapidly and become perfect.
Conclusions.In recent years, with the improvement of market requirements for the rapid detection technology of pesticides, organophosphorus pesticides, as an important part of the pesticide market, whose development speed of the rapid detection technology is very rapid.There are a wide variety of traditional detection technologies for pesticide, and each of them have own pros and cons, with development difficulties (Chen et   Дата надходження до редакції: 01.12.2020 р. (Arduini et al., 2019; Pundir et al., 2019; Sgobbi & Machado, 2018).3. Fluorescence detection techniques Fluorescence detection method is based on the different material molecules, the different absorption and reaction of light wavelength.This technology has high sensitivity, but it is limited to the luminous pesticide, and the non-luminous pesticide still needs to be added with fluorescent agent, and is susceptible to the interference of external factors, with poor adaptability (Ouyang et al., 2021; Wang et al., 2021).In recent years, through the fusion of biosensors, this detection technology has also made great progress (Chen et al, 2021; Han et al., 2021; Liang et al., 2021; Lin et al., 2021).The fluorescence sensor has the advantages of simple operation, quick response, high sensitivity and good reproducibility.The fluorescence sensor consists of two parts: the fluorescence signal element and the recognition element.Enzymes, antibodies, aptamers and molecularly imprinted polymers (MIP) are combined with nanomaterials to further enrich the types of fluorescence sensors al., 2021; C. J. Li et al., 2021; J. J. Li et al., 2021; Liang et al., 2021; Lin et al., 2021; Teysseire et al., 2021).At present, the rapid detection methods in the pesticide market tend to be more and more cross-fusion with various detection technologies.With the progress of science and technology, the development of new nanomaterials also makes great contributions to the improvement of rapid detection technology.Especially for the biosensor technol-ogy, who highly require for new material, the development of nanomaterials directly promotes the progress of this technology (Burratti et al., 2021; Du et al., 2021; M. Li et al., 2021; Ren et al., 2021; X. Y. Zhou et al., 2021).As the cross-fusion of a variety of rapid detection technologies, biosensor technology shows strong combination, and is suitable for a variety of rapid detection method of combining.Through the combination of biosensor detection technology and other rapid detection technologies, many difficulties in the development of rapid detection technology have been overcome.The advantages of rapid detection technology, such as enzyme inhibition detection technology, fluorescence detection and spectrophotometric detection technology, have been amplified, therefore the rapid detection techniques become more extensive and faster (Badawy, 2021; Cao et al., 2020; Singh et al., 2020; Q. S. Wei et al., 2020; N. Yang et al., 2020).References: 1. Caria, G., Proix, N., Mougin, C., Ouddane, B., & Net, S. (2021).A new, simple, efficient and robust multi-residue method based on pressurised-liquid extraction of agricultural soils to analyze pesticides by liquid chromatography coupled with a high resolution quadrupole time-of-flight mass spectrometer.International Journal of Environmental Analytical Chemistry.doi: 10.1080/03067319.2021.1889531 2. Loganathan, S., & Murugan, T. (2017 . With the rapid development of nanomaterials, multi-cross rapid detection technologies based on nanomaterials have a great breakthrough in sensor technology improvement, and biosensor technology has a huge development advantage in rapid detection technology (He et al., 2019; Lei et al., 2018; Lu et al., 2018; Wu et al. 2017).