Comparison of mild extraction procedures for determination of plant-available arsenic compounds in soil

In this work three mild extraction agents for determination of plant-available fractions of elements in soil were evaluated for arsenic speciation in soil samples. Pepper (Capsicum annum, L.) var. California Wonder was cultivated in pots, and aqueous solutions of arsenite, arsenate, methylarsonic acid, and dimethylarsinic acid, at a concentration of 15 mg As kg^–1 soil, were added at the beginning of the experiment. Control pots (untreated) were also included. Deionized water, 0.01 mol L^–1 CaCl₂, and 0.05 mol L^–1 (NH₄)₂SO₄ were used to extract the plant-available fraction of the arsenic compounds in soil samples collected during the vegetation period of the plants. Whereas in control samples the extractable arsenic fraction did not exceed 1% of total arsenic content, soil amendment by arsenic compounds resulted in extraction of larger amounts, which varied between 1.4 and 8.1% of total arsenic content, depending on soil treatment and on the extracting agent applied. Among arsenic compounds determined by HPLC–ICPMS arsenate was predominant, followed by small amounts of arsenite, methylarsonic acid, and dimethylarsinic acid, depending on the individual soil treatment. In all the experiments in which methylarsonic acid was added to the soil methylarsonous acid was detected in the extracts, suggesting that the soil bacteria are capable of reducing methylarsonic acid before a further methylation occurs. No significant differences were observed between analytical data obtained by using different extraction procedures.     

New methods for acceleration of meat sample preparation prior to determination of the metal content by atomic absorption spectrometry

Focused microwave-assisted digestion and ultrasound leaching have been applied for the extraction of Pb, Cd, Cr, Cu, Fe, Zn, Ca, and Mg from raw meat. Semimembranous muscle (SM) of raw pig ham was used for optimizing both the digestion and extraction steps by multivariate approaches. The detection and quantification limits were 0.5 and 0.9 g kg^–1 for Pb, 0.06 and 0.1 g kg^–1 for Cd, 0.2 and 1.2 g kg^–1 for Cr, 0.4 and 3 g kg^–1 for Cu, 0.04 and 0.1 mg kg^–1 for Fe, 0.012 and 0.017 mg kg^–1 for Zn, 0.3 and 0.4 mg kg^–1 for Ca, and 0.01 and 0.03 mg kg^–1 for Mg. The precision, expressed as relative standard deviation (RSD), ranged between 2.5 and 9.6% for focused microwave-assisted digestion and between 3.5 and 10.6% for ultrasound leaching. The methods were then compared with a reference method and applied to a certified reference material (bovine muscle 184, from the BCR). The t-test, applied to the results obtained from focused microwave-assisted digestion, revealed that they are in agreement (p>0.01) with the certified and estimated values in the case of Pb, Cd, Cr, Cu, Fe, Ca, Mg, and Zn but not in that of Fe. In the case of ultrasound leaching, only the extraction of Pb, Cu, and Ca was quantitative. The method based on microwave digestion provides more accurate and precise results than ultrasound leaching. These new procedures have many advantages with regards to conventional methods, namely, reduction of the extraction time, simplification of the process, avoidance of chemical emissions to the atmosphere, and no losses of metals by volatilization.     

LC�CMS�CMS Determination of Gizzerosine in Poultry Feed

A new selective method for the determination of the bioactive amine gizzerosine in poultry feed is presented based on hydrophilic interaction chromatography coupled to electrospray ionisation and tandem quadrupole mass spectrometry. The protonated molecular ions were selected for fragmentation and scanning of the two major product ions using the mass analyser in the multiple reaction monitoring mode. The analytical methodology included acid hydrolysis of feed sample aliquots and desalting and crude clean-up of hydrolysates using cation-exchange chromatography on a polymeric solid-phase extraction sorbent. Mean overall recoveries (n = 9) were 68?C82% in spike-recovery experiments. The limit of detection was 0.25 mg kg^?1. The method was applied to the analysis of fish meal and fish meal-containing poultry feed samples. Although gizzerosine could not be detected in any of the samples, it was found in fish meal made from sand eel after heating to 130 °C for 24 h.     

Dynamic ultrasound-assisted leaching of essential macro and micronutrient metal elements from animal feeds prior to flame atomic absorption spectrometry

A method for routine analysis of essential metal elements in animal feeds using a dynamic and automated ultrasound-assisted extractor is proposed here. Owing to the different concentration of the essential metal elements in the samples, two macronutrients—namely, Ca and Mg—and three micronutrients or trace elements—namely, Fe, Cu and Zn—were selected as models for the optimisation and characterisation of the proposed method by using experimental design methodology. Moreover, the extraction kinetics and influence of the particle size on the extraction efficiency were studied. The detection and quantification limits ranged between 2.9 and 40 g kg^–1 and between 7.9 and 95.5 g kg^–1, respectively. The precision, expressed as repeatability relative standard deviation (RSD) and as within-laboratory RSD, ranged between 1.86 and 5.66% and between 5.06 and 6.15%, respectively. The proposed approach allows the extraction of these metal elements from animal feeds with extraction efficiencies similar to those provided by the AOAC Official Method 968.08, but with a drastic reduction in both the extraction time (18 min versus 4.5 h) and sample handling, and using smaller volumes of extractant (an acid aqueous solution).     

Screening and Monitoring of Herbicides Behaviour in Soils by Enzyme Immunoassays

Abstract

A simplified approach to screen cropland for residues of atrazine and its main metabolite deethylated atrazine has been presented. A time-saving and cost-effective screening method has been developed using an aqueous extraction step. The measurement of the extracts was done by immunoassay technique (ELISA). Antibodies against atrazine and deethylated atrazine were used in the study. The overall detection limit of the analysis of atrazine residues in soil is 1 μg kg^?1 and 2 μg kg^?1 for its deethylated metabolite, respectively. It is shown that this approach yields adequate information to judge the ground-water hazard potential of treated fields.     

Adsorption of Phenylalanine from Casein Hydrolysates

The specific diet therapy for phenylalaninemies requires special hydrolysates of proteins where phenylalanine content is reduced to approx 0.53% of the amino acids present. In previous work, Amberlite XAD-4 resin was used to retain phenylalanine from an acid hydrolysate of casein. It was also observed that the adsorption isotherm of phenylalanine on the resin showed a convex pattern that allowed a frontal chromatography. In the present study, this technique was improved, aiming at the processing of larger hydrolysates volumes. This was achieved with the use of two sequential columns (50 × 1 cm), each containing 34 cm³ of the resin, and joined through a 1-cm long tygon, tube 1 mm diameter. This system was used to process 100 mL of casein acid hydrolysate containing 12 g of free amino acid and allowed the reduction of phenylalanine content from 4.39 to 0.14% of the total amino acids present, within 1 h. It was also observed that this technique could not be directly applied to enzymatic hydrolysates of casein unless they were especially produced for this purpose, which means that in this kind of hydrolysate, phenylalanine should be free or linked in small adsorptive peptides.     

Influence of the Degree of Hydrolysis on Functional Properties and Antioxidant Activity of Enzymatic Soybean Protein Hydrolysates

Soybean protein hydrolysates were prepared using two proteolytic enzymes (Alcalase and Protamex) and the degree of hydrolysis (DH) and their functional and antioxidant properties were evaluated. The highest DH value was 20%, with a yield of 19.77% and protein content of 51.64%. The total amino acid content was more than 41% for all protein hydrolysates. The protein hydrolysates from Protamex at pH 2.0 had excellent solubility, emulsifying activity, and foaming capacity, at 83.83%, 95.03 m²/g, and 93.84%, respectively. The water-holding capacity was 4.52 g/g for Alcalase, and the oil-holding capacity was 4.91 g/g for Protamex. The antioxidant activity (62.07%), as measured by the samples’ reaction with DPPH (2,2-diphenyl-1-picrylhydrazyl) and the reducing power (0.27) were the strongest for Protamex. An ABTS activity rate of 70.21% was recorded for Alcalase. These findings indicated a strong potential for the utilization of soybean protein hydrolysates to improve the functional properties and antioxidant activity of soybeans as well as their nutritional values.     

Rapid method for determination of phenylurea herbicides in milk

Summary A method has been developed for the determination of thirteen phenylurea herbicide residues in milk. It involves one-step solvent extraction of the milk with methanol by ultrasonication. The extract is cleaned up on an Amberchrom resin cartridge. Reversed-phase, gradient elution, high-performance liquid chromatography with UV detection at 242 nm is used to analyse the residues. The recovery of thirteen phenylurea pesticides is quantitative, ranging from 71.4% to 97.9% for the individual herbicides investigated at concentrations around 0.05 mg kg^–1 and from 65.1% to 95.6% around 0.005 mg kg^–1. The method is not associated with any of the emulsion problems common to conventional solvent extraction, which considerably reduce the sample clean-up process compared with existing methods.     

Residue analysis of fosthiazate in cucumber and soil by QuEChERS and GC-MS

A convenient method was developed for the determination and validation of fosthiazate in cucumber and soil. The procedure is based on liquid partitioning with acetonitrile followed by dispersive solid phase extraction as the clean-up step, after which samples were analysed by gas chromatography-mass spectrometry (GC-MS). The average recoveries ranged from 91.2 % to 99.0 % with relative standard deviations (RSDs) of less than 6.05 %, at three fortification levels (0.02 mg kg^?1, 0.1 mg kg^?1, 0.5 mg kg^?1) in cucumber and soil, and the limits of quantification (LOQs) for fosthiazate were all established at 0.02 mg kg^?1. The proposed method was applied successfully to analyses of the dissipation and residue of fosthiazate in field trials. The dissipation rate of fosthiazate was described using pseudo-first-order kinetics with a half-life of 4.33 days and 4.08 days in soil in Beijing and Shandong, respectively. In the terminal residue experiment, fosthiazate residues in cucumber and soil were clearly below the maximum residue level (MRL, 0.2 mg kg^?1) set in China.     

Determination of pesticides and PCBs in honey by solid-phase extraction cleanup followed by gas chromatography with electron-capture and nitrogen–phosphorus detection

A multiresidue method for determination of 15 organochlorine pesticides (OCPs), six polychlorinated biphenyls (PCBs), and seven organophosphorus pesticides (OPPs) is implemented for routine determinations of residues in honey. The method involves solid-phase extraction cleanup and determination by GC–ECD/NPD. Quantitation limits ranged from 0.1 to 0.6 g kg^–1 honey for OCPs and PCBs, and from 5.0 to 25.0 g kg^–1 honey for OPPs. Recoveries of OCPs ranged between 77.4 and 94.0%; for PCBs they were from 63.8 to 73.5%. Recovery assays for OPPs varied from 66.7 to 98.1%. The method was applied to the analysis of 111 honey samples from Aragón, Spain. The results obtained indicated a low level of contamination by pesticide residues and PCBs, which can contribute to ensuring the consumer has a safe wholesome supply of honey.     

Biodegradation of imidacloprid in sandy loam soil by Bacillus aerophilus

A study of the biodegradation of imidacloprid in soil was carried out under laboratory conditions. Sandy soil samples were fortified with imidacloprid at 50, 100 and 150 mg kg^?1 along with 45 x 10⁷ colony forming units (cfus) of Bacillus aerophilus and the samples were compared with unamended soil. The samples were extracted with acetonitrile, cleaned up by treatment with primary secondary amine sorbent and graphitised carbon black. The residues of imidacloprid and its metabolites were analysed by high performance liquid chromatography. The parent compound, imidacloprid, was found to be more persistent in both the treatments. Among metabolites, the highest values were obtained for urea and olefin while 5-hydroxy, 6-chloronicotinic acid (6-CNA), nitrosimine and nitroguanidine (NTG) were also observed in all the treatments in amended soil. In case of unamended (control) soil, 6-CNA was found to be the most persistent metabolite followed by olefin, urea, 5-hydroxy, nitrosimine and NTG metabolites. Total imidacloprid residues for control soil samples followed first-order kinetics at 50 and 150 mg kg^?1 but in case of control imidacloprid fortified at 100 mg kg^?1, the total residues of imidacloprid and its metabolites followed pseudo-first-order kinetics. The respective half-life value for 50 mg kg^?1 was 25.08 days and 30.10 days for both 100 and 150 mg kg^?1. However, total imidacloprid residues followed pseudo-first-order kinetics for its applications at 50, 100 and 150 mg kg^?1 in sandy loam soil amended with B. aerophilus. The half-life values for 50, 100 and 150 mg kg^?1 were worked out to be 14.33, 15.05 and 18.81 days, respectively. With the use of B. aerophilus, the reduction percentage of initial applied dose imidacloprid in sandy loam soil was found to be higher in all the three doses as compared to that of the control samples.     

Determination of carbendazim,thiabendazole, and<Emphasis Type="Italic"> o-</Emphasis>phenylphenol residues in lemons by HPLC following sample clean-up by ion-pairing

An efficient analytical method is presented involving effective sample clean-up with solid-phase extraction and HPLC-UV analysis for the simultaneous determination of carbendazim, thiabendazole, and o-phenylphenol residues in lemons. Sample preparation involves extraction with acetonitrile acidified with trifluoroacetic acid and an ethyl acetate/petroleum ether mixture. Purification of the crude extract was carried out with liquid–liquid partitioning after addition of an aqueous ammonia solution. Final clean-up was performed on polymeric reversed-phase cartridges pretreated with sodium dodecyl sulfate. Chromatographic analysis was performed on a reversed-phase HPLC column isocratically eluted with an acetonitrile/water/ammonia mixture and UV detection at 254 nm. The chromatographic method is repeatable, reproducible, and sensitive. Fungicide recoveries from lemon samples fortified at levels of 5 and 1 mg kg^–1 were 81–85% for carbendazim, 96–98% for thiabendazole, and 81–106% for o-phenylphenol with coefficients of variation of 2.5–7.4%. Detection limits for carbendazim, thiabendazole, and o-phenylphenol in lemons were 0.21, 0.27, and 0.51 mg kg^–1, respectively.     

Analysis of aged sulfadiazine residues in soils using microwave extraction and liquid chromatography tandem mass spectrometry

An efficient extraction of sulfadiazine residues from soils is difficult, as sulfadiazine is known to form quickly sequestering residues. The objective of this study was to optimize an exhaustive extraction for aged residues of sulfadiazine and its two major metabolites, N-acetylsulfadiazine and 4-hydroxysulfadiazine, from soil. For this purpose two representative used agricultural soils (Luvisol, Cambisol) were blended with manure derived from [¹⁴C]sulfadiazine-treated pigs and incubated at 10 °C in the laboratory. After different extraction tests with various solvent mixtures (two- to four-component mixtures with water, methanol, acetonitrile, acetone, and/or ethyl acetate), different pH values (pH 4 and 9), and extraction temperatures (up to 200 °C), soil extracts were measured by liquid scintillation counting and liquid chromatography coupled to tandem mass spectrometry. With respect to sulfadiazine yields, stability of soil extracts, and the amount of coextracted matrix, a microwave extraction of soil (15 min, 150 °C) using acetonitrile/water 1:4 (v/v) is the method of choice for the exhaustive extraction of aged sulfadiazine residues from soils.     

Ethanol fermentation of acid hydrolysate of municipal solid waste

Acid hydrolysates of municipal solid waste (MSW) demonstrate poor fermentability which stems from the presence of various toxic substances liberated from the lignocellulosic material during the hydrolysis process and from toxic materials originating in the raw substrate. Ethanol yields of MSW hydrolysates were found to correlate with the severity of the hydrolysis conditions. The yields varied between 17% and 75% of the theoretical. It is shown that inhibition effects in MSW hydrolysates can be overcome by several treatment methods, with final ethanol yields, after 24 h fermentation, of between 81 and 94% of theoretical.The most effective method of improving fermentation yields was found to be a combined treatment of heat at 121 °C under pressure of 1.2 atm, prior to fermentation, with fermentation at the elevated pH of 6.5. This method was found to give good results for all the hydrolysates tested.High yeast inocula, heat treatment under pressure of 1.2 atm, and fermentation at pH 6.5 (without heating) were found to be only partially effective in most cases and of no beneficial effect in others.Other methods, including yeast acclimatization, adsorption, neutralization at high temperature or at high pH, and a reduced oxidation reduction potential were found to have no effect on the fermentation results.     

Development of One-Step Non-Solvent Extraction and Sensitive UHPLC-MS/MS Method for Assessment of N-(n-Butyl) Thiophosphoric Triamide (NBPT) and N-(n-Butyl) Phosphoric Triamide (NBPTo) in Milk

N-(n-butyl) thiophosphoric triamide (NBPT) is a urease inhibitor utilised in urea-based fertilizers. In Ireland, fertilizer treated with NBPT is applied to pasture to mitigate both ammonia and nitrous oxide emissions, but concerns arise as to the potential for residues in milk products. A quick ultrafiltration extraction and ultra-high performance liquid chromatography coupled with mass spectrometry triple quadrupole (UHPLC-MS/MS) quantitation method was developed and validated in this study. The method was applied in the analysis of samples collected from a field study investigating potential transfer of NBPT residues into milk. NBPT and NBPTo residues, were extracted from fortified milk samples and analysed on a UHPLC-MS/MS with recoveries ranging from 74 to 114%. Validation of the UHPLC-MS/MS method at low (0.0020 mg kg⁻¹) and high (0.0250 mg kg⁻¹) concentration levels in line with SANTE/12682/2019 showed overall trueness in the range of 99 to 104% and precision between 1 and 10%, RSD for both compounds. The limit of quantitation (LOQ) was 0.0020 mg kg⁻¹ and other tested parameters (linearity, sensitivity, specificity, matrix effect, robustness, etc.) satisfied acceptance criteria. Stability assessment using spiked samples revealed the compounds were stable in raw and pasteurised milk for 4 weeks at –80 °C storage temperature. Maintaining samples at pH 8.5–9.0 further improved stability. Analysis of 516 milk samples from the field study found that NBPT and NBPTo concentrations were below the LOQ of 0.0020 mg kg⁻¹, thus suggesting very low risk of residues occurring in the milk. The method developed is quick, robust, and sensitive. The method is deemed fit-for-purpose for the simultaneous determination of NBPT and NBPTo in milk.     

Elucidation of Metal‐Ion Accumulation Induced by Hydrogen Bonds on Protein Surfaces by Using Porous Lysozyme Crystals Containing RhIII Ions as the Model Surfaces

Metal‐ion accumulation on protein surfaces is a crucial step in the initiation of small‐metal clusters and the formation of inorganic materials in nature. This event is expected to control the nucleation, growth, and position of the materials. There remain many unknowns, as to how proteins affect the initial process at the atomic level, although multistep assembly processes of the materials formation by both native and model systems have been clarified at the macroscopic level. Herein the cooperative effects of amino acids and hydrogen bonds promoting metal accumulation reactions are clarified by using porous hen egg white lysozyme (HEWL) crystals containing Rh^III ions, as model protein surfaces for the reactions. The experimental results reveal noteworthy implications for initiation of metal accumulation, which involve highly cooperative dynamics of amino acids and hydrogen bonds: i) Disruption of hydrogen bonds can induce conformational changes of amino‐acid residues to capture Rh^III ions. ii) Water molecules pre‐organized by hydrogen bonds can stabilize Rh^III coordination as aqua ligands. iii) Water molecules participating in hydrogen bonds with amino‐acid residues can be replaced by Rh^III ions to form polynuclear structures with the residues. iv) Rh^III aqua complexes are retained on amino‐acid residues through stabilizing hydrogen bonds even at low pH (≈2). These metal–protein interactions including hydrogen bonds may promote native metal accumulation reactions and also may be useful in the preparation of new inorganic materials that incorporate proteins.     

Homogeneous liquid-liquid extraction combined with gas chromatography-electron capture detector for the determination of three pesticide residues in soils

In this study, a new method was developed for analyzing malathion, cypermethrin and lambda-cyhalothrin from soil samples by using homogeneous liquid–liquid extraction (HLLE) and gas chromatography with electron capture detector (GC–ECD). Acetone was used as extraction solvent for the extraction of target pesticides from soil samples. When the extraction process was finished, the target analytes in the extraction solvent were rapidly transferred from the acetone extract to carbon tetrachloride, using HLLE. Under the optimum conditions, linearity was obtained in the range of 0.05–40 μg kg⁻¹ for malathion, 0.04–10 μg kg⁻¹ for lambda-cyhalothrin and 0.05–50 μg kg⁻¹ for cypermethrin, respectively. Coefficients of correlation (r²) ranged from 0.9993 to 0.9998. The repeatability was carried out by spiking soil samples at concentration levels of 2.5 μg kg⁻¹ for lambda-cyhalothrin, and 10 μg kg⁻¹ for malathion and cypermethrin, respectively. The relative standard deviations (RSDs) varied between 2.3 and 9.6% (n = 3). The limits of detection (LODs), based on signal-to-noise ratio (S/N) of 3, varied between 0.01 and 0.04 μg kg⁻¹. The relative recoveries of three pesticides from soil A1, A2 and A3 at spiking levels of 2.5, 5 and 10 μg kg⁻¹ were in the range of 82.20–91.60%, 88.90–110.5% and 77.10–98.50%, respectively. In conclusion, the proposed method can be successfully applied for the determination of target pesticide residues in real soil samples.     

Chemical characterisation of biosludge from a wastewater treatment plant in a neutral sulphite semi-chemical pulp mill by single and sequential extraction of heavy metals and micro-/macronutrients — a case study

The main impetus for utilising the biosludge from the neutral sulphite semi-chemical pulping process is the Finnish legislation which from 1st January 2016 prohibits the deposition of this residue in landfills in Finland. The dry matter content of the biosludge in this case study was low (12.1 mass %), meaning that incineration of this residue is uneconomical. The biosludge was rich in P (6260 mg kg^?1). This, together with the high total organic carbon value of 459 g kg^?1 and the metal concentrations (As, Cd, Cr, Cu, Ni, Pb, Zn and Hg) lower than the Finnish permissible limits for land application, supports wide and various end-uses for this residue. Except for S (27600 mg kg^?1) and Cd (1.4 mg kg^?1), the other heavy metal concentrations in the biosludge were lower than the maximum values for heavy metal concentrations in a non-contaminated soil referred to the literature. From the utilisation perspective, and in view of the high levels of S and Na, this residue could efficiently be used, for example, to landscape landfills.     

Dissipation dynamics and final residues of flutriafol in tobacco and soil using ultrasound-assisted extraction before liquid chromatography/tandem mass spectrometry

The dissipation dynamics and final residues of flutriafol on tobacco plant and soil were studied under field conditions. The residues of flutriafol in soil, green tobacco leaves and cured tobacco leaves were extracted by ultrasound-assisted extraction, cleaned up by dispersive solid-phase extraction and detected by liquid chromatography with tandem mass spectrometry. The limits of detection of flutriafol in soil, green tobacco leaves and cured tobacco leaves were 0.006, 0.033 and 0.033 mg·kg^?1, respectively. The limits of quantification of flutriafol in soil, green tobacco leaves and cured tobacco leaves were 0.02, 0.1 and 0.1 mg·kg^?1, respectively. Recoveries were 72.9–102% with relative standard deviations of less than 12% in soil and tobacco matrix. For field experiments, the half-lives of flutriafol in soil and green tobacco leaves were 9.2–11.5 and 9.5–11.1 days, respectively. At harvest, the final residue levels of flutriafol in cured tobacco leaves collected 21 days after one application at the recommended dosage were below 2.0 mg/kg. The maximum residue limit maximum residue limit (MRL) for flutriafol in tobacco has not yet been established in any countries. The data could help the Chinese Government to establish the MRL of flutriafol in tobacco and provide guidance on the proper use of flutriafol.     

Dissipation dynamics of fenamidone and propamocarb hydrochloride in pepper,soil and residue analysis in vegetables by ultra-performance liquid chromatography coupled with tandem mass spectrometry

In this study, a rapid and sensitive method was developed for determining fenamidone and propamocarb hydrochloride residues in vegetables and soil by ultra-performance liquid chromatography-tandem mass spectrometry. The dissipation dynamics of fenamidone and propamocarb hydrochloride in pepper and soil was investigated in Beijing, Henan and Shandong provinces. The target compounds were extracted with methanol and cleaned with dispersive solid phase extraction using primary secondary amine. Two pairs of precursor product ion transitions for fenamidone and propamocarb hydrochloride were measured and evaluated. Average recoveries of fenamidone in potato, tomato, cabbage, pepper and soil at three levels (10, 100 and 1000 μg kg^?1) ranged from 76.91% to 107.31% with relative standard deviations (RSDs) from 2.74% to 10.87% (n = 15). The average recoveries of propamocarb hydrochloride ranged from 74.84% to 97.96% with RSDs from 2.43% to 16.16% (n = 15). The limits of detection (LODs) for fenamidone in each matrix were 0.131–0.291 μg kg^?1, and the limits of quantification (LOQs) were 0.436–0.970 μg kg^?1. The LODs for propamocarb hydrochloride were 0.125–0.633 μg kg^?1, and the LOQs were 0.417–2.11 μg kg^?1. The results also showed that the dissipation of fenamidone and propamocarb hydrochloride in pepper and soil followed first-order kinetics model more than that of bi-exponential models. The half-lives of propamocarb hydrochloride were 6.90–15.78 days in pepper and 13.56–23.02 days in soil. The half-lives of fenamidone were 7.48–11.29 days in pepper and 35.18–42.78 days in soil.