QuEChERS GC–MS validation and monitoring of pesticide residues in different foods in the tomato classification group

High-throughput screening and quantitative analysis of hidden ingredients in plant protection products by GC-MS/MS

Hidden ingredients in plant protection products (PPPs) threaten public health, food trade, and the environment. In this study, we developed a high-throughput screening method of 639 hidden ingredients in PPPs using GC-MS/MS in multiple reaction monitoring mode. Results showed that the qualitative criteria of retention time (tR) shift and uncertainty of qualifier to quantifier ratio in the commercially available Shimadzu Smart Pesticides Database were set at < 0.17 min and < 30%, respectively, which could be used to tentatively identify compounds without standards. The limits of quantification were 0.01-0.05 mg/kg. A wide linear range of 10-1000 μg/L was observed with R2 ≥ 0.975. Recoveries from three types of PPP formulations were 62.08%- 126.3%, with relative standard deviations < 15.7%. Finally, this method was applied to screen and quantify hidden ingredients in 91 plant protection products (PPPs) samples collected from online sales in China. Only one hidden ingredient, dimethomorph (1.6 g/kg), was detected in the polyoxin formulation (15% wettable powder). The results will be helpful in assessing the potential risks of hidden ingredients in PPPs.

Application of magnetic carbon nano-onions in dispersive solid-phase extraction combined with DLLME for extraction of pesticide residues from water and vegetable samples

A dispersive solid-phase microextraction method based on magnetic carbon nano-onions (MCNOs) was developed for the extraction and preconcentration of some pesticides from water and vegetable samples. For more cleanup and preconcentration, a dispersive liquid-liquid microextraction (DLLME) method was employed after performing the first step. In this method, firstly, MCNOs were prepared and then used for adsorption of the analytes from the sample solution. After that, the adsorbed analytes were eluted with an appropriate water-miscible organic solvent and used as a dispersive solvent in the following DLLME procedure. The extracted analytes were quantified by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Various factors affecting the method efficiency such as sorbent weight, salt effect, pH, temperature, and type and volume of eluent and extraction solvent were optimized. This method showed wide linear ranges with a coefficient of determination ≥ 0.994, and low limits of detection (0.001-0.005 ng mL^-1) and quantification (0.003-0.019 ng mL^-1) under optimal conditions. Also, a good precision (relative standard deviation ≤ 8.6%) for five replicates and a satisfactory accuracy (mean relative recoveries between 82 and 99%) were obtained. It can be considered as an efficient and environment friendly method for the extraction of analytes from vegetable and fruit juices and water samples.

Development of a simple HPLC procedure for the determination of prochloraz residues in mushrooms

A simple HPLC-UV procedure is described in our paper which is suitable for the rapid and cost-efficient determination of prochloraz in mushrooms. Prochloraz is the only fungicide in EU which use is allowed in mushroom production. The aim of our work was the development of a simple method that is suitable for the control of this pesticide in everyday analyses during mushroom production. The procedure involves a simple sample preparation method based on solid-liquid extraction (modified QuEChERS extraction method EN 15662) followed by an HPLC-UV determination (recovery: 97–99%; limit of detection LOD: 0.01 mg/kg; limit of quantification LOQ: 0.05 mg/kg).

Magnetic graphene coated inorganic-organic hybrid nanocomposite for enhanced preconcentration of selected pesticides in tomato and grape

The new magnetic graphene based hybrid silica-N-[3-(trimethoxysilyl)propyl]ethylenediamine (MG@SiO₂-TMSPED) nanocomposite was synthesized via sol-gel process, and used as an effective adsorbent in magnetic solid phase extraction (MSPE) of three selected pesticides followed by gas chromatography micro-electron capture detection (GC-μECD). The adsorbent was characterized using Fourier transform-infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDXS) techniques. The analytical validity of the developed method was evaluated under optimized conditions and the following figures of merit were obtained: linearity, 1-20μgkg^-1 with good determination coefficients (R²=0.995-0.999); limits of detection (LODs), 0.23-0.30μgkg^-1 (3×SD/m, n=3); and limits of quantitation (LOQ), 0.76-1.0μgkg^-1 (10×SD/m, n=3). The precision (RSD%) of the proposed MSPE method was studied based on intra-day (3.43-8.83%, n=3) and inter-day (6.68-8.37%, n=12) precisions. Finally, the adsorbent was applied to determination of pesticides in tomato and grape samples and good recoveries were obtained in the range from 82 to 113% (RSDs 5.1-8.1%, n=3).

Chemometric-assisted QuEChERS extraction method for post-harvest pesticide determination in fruits and vegetables

An effective analysis method was developed based on a chemometric tool for the simultaneous quantification of five different post-harvest pesticides (2,4-dichlorophenoxyacetic acid (2,4-D), carbendazim, thiabendazole, iprodione, and prochloraz) in fruits and vegetables. In the modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method, the factors and responses for optimization of the extraction and cleanup analyses were compared using the Plackett-Burman (P-B) screening design. Furthermore, the significant factors (toluene percentage, hydrochloric acid (HCl) percentage, and graphitized carbon black (GCB) amount) were optimized using a central composite design (CCD) combined with Derringer's desirability function (DF). The limits of quantification (LOQs) were estimated to be 1.0 μg/kg for 2,4-D, carbendazim, thiabendazole, and prochloraz, and 1.5 μg/kg for iprodione in food matrices. The mean recoveries were in the range of 70.4-113.9% with relative standard deviations (RSDs) of less than 16.9% at three spiking levels. The measurement uncertainty of the analytical method was determined using the bottom-up approach, which yielded an average value of 7.6%. Carbendazim was most frequently found in real samples analyzed using the developed method. Consequently, the analytical method can serve as an advantageous and rapid tool for determination of five preservative pesticides in fruits and vegetables.

Application of the QuEChERS method for the determination of organochlorine pesticide residues in Brazilian fruit pulps by GC-ECD

The Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was applied to the extraction of 14 organochlorine pesticides (OCPs) residues from commercial fruit pulps available in supermarkets in Fortaleza, Northeastern Brazil. The analyses were carried out by gas chromatography (GC), coupled to an electron-capture detector (ECD), and were confirmed by GC-tandem mass spectrometry (MS). The parameters of the analytical method, such as accuracy, precision, linear range, limits of detection and quantification, were determined for each pesticide. The results showed good linearity (R² ≥ 0.9916) and the overall average recoveries were considered satisfactory obtaining values between 69 and 110%, RSD of 2-15 %, except for hexachlorobenzene (HCB) in açai, acerola and guava pulp samples. The OCPs were detected in guava (α-HCH; lindane) and soursop (α, β-HCH isomers) samples. The QuEChERS method and GC-ECD were successfully used to analyze OCPs in commercially available Brazilian fruit pulps and can be applied in routine analytical laboratories.

Dissipation kinetics and degradation mechanism of amicarbazone in soil revealed by a reliable LC-MS/MS method

A sensitive and reliable analytical method was developed for simultaneous determination of amicarbazone (AMZ) and its two major metabolites including desamino amicarbazone (DA) and isopropyl-2-hydroxy-DA-amicarbazone (Ipr-2-OH-DA-AMZ) in soil for the first time. Targeted analytes were extracted and purified using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure, and then analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with a total run time of 9 min. The established approach was extensively validated by determining the linearity (R (2) ≥ 0.99), recovery (84-96 ), sensitivity (limits of quantification at 5-10 μg kg(-1)), and precision (RSDs ≤12 %). Based on the methodological advances, the subsequent dissipation kinetics and degradation mechanism of amicarbazone in soil were thoroughly investigated in an illumination incubator. As revealed, AMZ was easily degraded with the half-lives of 13.9-19.7 days in soil. Field trial results of AMZ (40 g a.i. ha(-1)) in Shanghai showed that the residues of AMZ and its metabolite Ipr-2-OH-DA-AMZ decreased from 0.505 mg kg(-1) (day 50) to 0.038 mg kg(-1) (day 365) and from 0.099 mg kg(-1) (day 50) to 0.028 mg kg(-1) (day 365), respectively, while the content of DA increased from 0.097 mg kg(-1) (day 50) to 0.245 mg kg(-1) (day 365). This study provided valuable data to understand the toxicity of AMZ and substantially promote its safe application to protect environment and human health.

Evaluation of GC-ICP-MS/MS as a New Strategy for Specific Heteroatom Detection of Phosphorus, Sulfur, and Chlorine Determination in Foods

For the first time in the literature, application of a GC-ICP-MS/MS method for the selective and sensitive detection of specific heteroatoms of phosphorus, sulfur, and chlorine has been accomplished. As a proof of concept, organophosphorus, organosulfur, and organochlorine pesticides in various food matrices have been studied. For the detection of organophosphorus and organosulfur pesticides, oxygen was used in the collision reaction cell (CRC) to convert P (m/z 31) to PO(+) (m/z 47) and S (m/z 32) to SO(+) (m/z 48). Similarly, ClH2(+) (m/z 37) was monitored after the reaction of Cl (m/z 35) with hydrogen in the CRC for the determination of organochlorine pesticides. Real food samples (baby food purees, fresh vegetables, loose tea) were screened for their pesticide content, following preparation of triplicate extracts using QuEChERS (quick, easy, cheap, effective, rugged, and safe). Excellent linearity with correlation coefficients R ≥ 0.997 was achieved, and the lowest detection limits obtained for the organophosphorus, organosulfur, and organochlorine pesticides were 0.0005, 0.675, and 0.144 μg/kg, respectively.

Evaluation of QuEChERS sample preparation and liquid chromatography-triple-quadrupole mass spectrometry method for the determination of 109 pesticide residues in tomatoes

A multiresidue method based on modified QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation, followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed and validated for the determination of 109 selected multiclass pesticides in tomatoes. The recovery yields ranged from 77.1% to 113.2%, with repeatabilities of 4.4-19.2% and within-laboratory reproducibilities of 7.1-18.4%. The limit of detections (LODs) for target analytes in tomato extract were between 0.5 and 10.8μgkg(-1), and the limit of quantifications (LOQs) were between 1.3 and 30.4μgkg(-1). The expanded measurement uncertainty was not higher than 30% for all target analytes. The method has been successfully applied to the analysis of 345 tomato samples obtained from local markets and tomato traders. Residues of acetamiprid, azoxystrobin and triadimefon were identified and measured in 9.6% of tomato samples, ranging from 0.015 to 0.37mgkg(-1).