ABSTRACT
Proquinazid is a new-generation fungicide authorized in the EU for combating powdery mildew infections in high-value crops. Due to the perishable nature of fruits, alternative analytical methods are necessary to protect consumer's health from pesticide residues. Currently, immunoassays are a well-established approach for rapidly monitoring chemical contaminants. However, the production of high-quality immunoreagents, such as antibodies and bioconjugates, is essential. This study presents a newly designed hapten that maintains the characteristic moieties of proquinazid unmodified. The linear aliphatic substituents of this molecule were used to introduce the spacer arm. A three-step synthesis strategy was optimized to prepare a hapten that displays the entire 6-iodoquinazolin-4(3H)-one moiety with excellent yields. The N-hydroxysuccimidyl ester of the hapten was activated and purified to prepare a protein conjugate with high hapten density, which was used as an immunogen. Antibodies were raised and competitive enzyme-linked immunosorbent assays were developed. To enhance the assay's sensitivity, two additional heterologous haptens were prepared by modifying the halogenated substituent at C-6. The optimized assays demonstrated low limits of detection in buffer, approximately 0.05 µg/L. When applied to the analysis of proquinazid in QuEChERS extracts of strawberry samples, the immunoassays produced precise and accurate results, particularly in the 10-1000 µg/kg range.
ABSTRACT
Acrylamide (AA) is produced through the reaction between sugars and amino acids present in starchy foods cooked at high temperature. It is classified as probably carcinogenic to humans. In 2019, the European Commission reported a list of foods for monitoring the presence of AA, which includes cereal snacks. This study presents the development and validation of an analytical approach for detecting AA in popcorn and corn-based snacks. It includes solid-liquid extraction and clean-up with dispersive solid phase extraction followed by analysis through liquid chromatography coupled with tandem mass spectrometry. The proposed method was characterized in terms of recoveries (84-105%), and precision (< 16.1%). Limits of quantification were 17 and 60 µg kg-1 for corn and popcorn, respectively. Sustainability of the methodology was evaluated using AGREEprep and BAGI, providing values of 0.43 and 65.0, respectively. Twenty-four corn-based products were analyzed, with AA levels from 219 to 418 µg kg-1.
Subject(s)
Acrylamide , Food Contamination , Tandem Mass Spectrometry , Zea mays , Zea mays/chemistry , Acrylamide/analysis , Acrylamide/chemistry , Food Contamination/analysis , Solid Phase Extraction/methods , Chromatography, High Pressure Liquid , Chromatography, Liquid/methods , Green Chemistry Technology , Liquid Chromatography-Mass SpectrometryABSTRACT
Citrinin is a hepato-nephrotoxic mycotoxin produced by fungal species. The Monascus purpureus fungus plays a crucial role in the fermentation of red rice to produce red yeast rice-based food supplements, which represent the primary source of human exposure to citrinin. In this study, a simple and sensitive analytical method was successfully developed and validated for the citrinin determination in these products. The extraction process involved a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) step and citrinin determination by ultra high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The proposed method provided satisfactory linearity, percentage of recovery from 82 to 104% with relative standard deviations (RSD) lower than 14%, and limits of detection and quantification of 0.07 µg/Kg and 0.24 µg/kg, respectively. Among the 14 samples analyzed, citrinin was found in two red rice samples (0.24 and 0.46 µg/kg) and in six food supplements (from 0.44 to 87 µg/kg).
Subject(s)
Citrinin , Dietary Supplements , Food Contamination , Oryza , Tandem Mass Spectrometry , Citrinin/analysis , Tandem Mass Spectrometry/methods , Chromatography, High Pressure Liquid , Dietary Supplements/analysis , Oryza/chemistry , Oryza/microbiology , Food Contamination/analysis , Monascus/metabolism , Monascus/chemistry , Biological Products/analysis , Biological Products/chemistryABSTRACT
A fast and simple procedure based on microextraction by packed sorbent (MEPS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the simultaneous quantification of 28 synthetic hallucinogens in oral fluids, including lysergic acid diethylamide and substances from NBOMe, NBOH, NBF, 2C, and substituted amphetamine categories. Extraction conditions such as type of sorbent, sample pH, number of charge/discharge cycles, and elution volume were studied. Hallucinogenic compounds were extracted from oral fluid samples using C18 MEPS, loading with 100 µL sample (adjusted to pH 7) in 3 cycles, washing with 100 µL deionized water, and eluting with 50 µL methanol in 1 cycle, giving quantitative recoveries and no significant matrix effects. Limits of detection from 0.09 to 1.22 µg L-1; recoveries from 80 to 129% performed in spiked oral fluid samples at 20, 50, and 100 µg L-1; and high precision with relative standard deviations lower than 9% were obtained. The proposed methodology was demonstrated to be appropriate for the simple and sensitive determination of NBOMe derivates and other synthetic hallucinogenic substances in oral fluid samples.
Subject(s)
Hallucinogens , Chromatography, Liquid , Tandem Mass Spectrometry/methods , Solid Phase Microextraction/methods , Limit of Detection , Chromatography, High Pressure Liquid/methodsABSTRACT
The water concentrations of 12 heavy and other metals/metalloids were analyzed seasonally along two horizontal-flow constructed wetlands (CWs) (Tancat Mília-TM and Tancat l'Illa-TLI) located within the Mediterranean Albufera de València Natural Park during 2020-2021. A wide-scope screening of pesticides present in waters was also performed. The two CWs were created to improve water quality and increase biodiversity. They currently receive effluent waters from two different tertiary-treatment wastewater plants, and the water flows along the CWs before being discharged into the main lagoon and a smaller lagoon in TM and TLI, respectively. TLI manages to reduce (Mn) or maintain the concentration of most of the studied elements (Zn, Ni, Hg, Cr, Fe Cd, Cu) at the same level as outside (67%). Only Al, Pb, B, and As remain at a higher concentration. TM also reduces Zn and Cu and keeps the concentration of Cr, Cd, and Hg (representing 42%). Al, Pb, B, and As remain at higher concentrations, as in TLI, but Ni, Fe, and Mn are also at higher concentrations. Although both CWs vary in their ability to remove elements, no risks to human health or the environment have been detected due to the low metal concentration in their outlets, all of them (except Hg) below the legal limits for environmental quality in the European Union. With the detection of 71 compounds in water in each CW area (26 herbicides, 26 insecticides, and 19 fungicides in TLI, and 29 herbicides, 23 insecticides, and 19 fungicides in TM), we also provide evidence of the impact of pesticides, which depends on the application method (helicopter, tractor), originated from areas with high agricultural pressure (chiefly rice crops) on systems (mainly TM) created to preserve biodiversity. Nevertheless, both systems provide crucial environmental services in water quality in this agrolandscape.
Subject(s)
Fungicides, Industrial , Herbicides , Insecticides , Mercury , Metalloids , Metals, Heavy , Pesticides , Water Pollutants, Chemical , Humans , Wetlands , Wastewater , Deuterium Oxide , Cadmium , Lead , Water Pollutants, Chemical/analysis , Metals, Heavy/analysis , Environmental Monitoring/methodsABSTRACT
Human biomonitoring (HBM) is a very useful tool for assessing human exposure to acrylamide (AA). In the framework of the Human Biomonitoring Initiative (HBM4EU) AA was included in its second list of priority substances due to the potential threat to human health. HBM data on AA are scarce, but the use of specific and sensitive biomarkers represents a reliable indicator of exposure. In this review an overview of available knowledge on HBM of AA is provided in terms of: i) preferred exposure biomarkers and matrices for the HBM of AA; ii) analytical methods for determining its biomarkers of exposure in the most used specimens; iii) current HBM data available; and iv) tools for interpreting HBM data for AA in relation to risk assessment. Finally, future trends in this field are discussed.
Subject(s)
Acrylamide , Biological Monitoring , Biomarkers , Environmental Monitoring/methods , Humans , Risk AssessmentABSTRACT
Synthetic cannabinoids are the second largest group of new psychoactive substances reported by the United Nations Office on Drugs and Crime in the last decade and case reports bring attention to its high potency effects and its severe toxicity, including fatalities. Moreover, synthetic cannabinoids are usually entirely metabolized and metabolic pathways for many new generation synthetic cannabinoids are still unknown. In this study, the metabolism of five third generation synthetic cannabinoids was evaluated using zebrafish (Danio rerio) larvae as 24-h in vivo model studied within 5 days after fertilization. The studied synthetic cannabinoids were MMB-CHMICA, ADB-CHMICA, ADB-CHMINACA, MDMB-CHMCZCA, and NNL-3, and the respective metabolites were identified by liquid chromatography-high resolution tandem mass spectrometry. Eleven, six, fourteen, eleven, and four metabolites were identified for MMB-CHMICA, ADB-CHMICA, ADB-CHMINACA, MDMB-CHMCZCA, and NNL-3, respectively, and metabolic pathways have been proposed. The use of zebrafish larvae, with a high degree of physiological and genetic homology to humans, is an emerging tool very useful for the identification of metabolic pathways of psychoactive substances. Results obtained in this study compared well with metabolites obtained previously for the same target molecules or structural analogous after in vitro incubation with human or rat hepatocytes. Thus, potential biomarkers for the evaluated compounds are the O-demethylated metabolite for MMB-CHMICA; the oxidative deamination to hydroxyl metabolite for ADB-CHMICA; hydroxyl metabolites at cyclohexylmethyl, tert-butyl, and indazole moieties for ADB-CHMINACA; hydroxyl metabolites at carbazole core, tert-butyl, or cyclohexylmethyl tail moieties for MDMB-CHMCZCA; and amide hydrolyzed, defluorinated, and dihydroxilated metabolite for NNL-3.
Subject(s)
Cannabinoids , Illicit Drugs , Animals , Cannabinoids/metabolism , Chromatography, Liquid/methods , Illicit Drugs/metabolism , Larva/metabolism , Rats , Zebrafish/metabolismABSTRACT
In this study, a gas chromatograph (GC) has been coupled to a drift tube ion mobility spectrometer (IMS) in order to develop an analytical procedure for the determination of psychoactive substances in oral fluids. Working parameters, including the GC-IMS interface ones, were adjusted in order to obtain sensitive and robust signals. A volume of 500 µL of oral fluid was extracted with 250 µL chloroform and, after centrifugation, were injected into the GC-IMS system. Amphetamine, methylone, α-PVP, ketamine, lidocaine, MPHP, cocaine, THJ-2201, and 5F-ADB were employed as model compounds, providing limits of detection from 6 to 15 µg L-1 and recoveries from 70 to 115% for field oral fluids spiked with target analytes at 250, 500, and 600 µg L-1. Moreover, two oral fluid certified reference materials were analysed by the proposed GC-IMS based methodology with obtained relative percentage errors lower than 8.4%, being the proposed GC-IMS procedure a reliable, selective, and sensitive technique for the determination of psychoactive substances in oral fluids.
Subject(s)
Cocaine , Pharmaceutical Preparations , Amphetamine , Cocaine/analysis , Gas Chromatography-Mass Spectrometry , Ion Mobility SpectrometryABSTRACT
In this study, a dual mixed-mode polymer sorbent was prepared via one-step thermally initiated polymerization of 4-vinylpyridine (VP), methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) for the solid-phase extraction (SPE) of basic and acidic drugs. The use of VP and MAA as ionizable functional monomers allowed the tailoring of ion-exchange and hydrophobic features of the polymer. The obtained polymer was characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. Next, the retention behavior of dual mixed-mode polymer towards basic and acidic drugs was investigated. Moreover, the practical capability of this novel material was tested for the extraction of relevant drugs such as cocaine, 3-methylmethcathinone, and diazepam in oral fluid samples. Recovery values (at different spiked levels in blank oral fluid samples), ranging from 69 to 99%, and limits of detection (LODs), between 0.10 and 0.25 µg L-1, were obtained.
Subject(s)
Methacrylates , Pharmaceutical Preparations , Polymers , Solid Phase ExtractionABSTRACT
Negative health effects of active and passive smokers have been widely described, but the effect of tobacco smoke on the skin has been less explored. In this study, an analytical methodology has been developed to evaluate the dermal permeation of hazardous compounds present in tobacco smoke, using an exposition chamber to simulate finite and infinite smoking conditions, in vitro vertical Franz diffusion cells, and Strat-M® membranes as human skin simulants. Moreover, the antipollution effect of three cosmetics has been evaluated, showing a significant efficacy to reduce dermal permeation of hazardous tobacco-smoke compounds such as of nicotine and aromatic hydrocarbons.
Subject(s)
Cosmetics , Tobacco Smoke Pollution , Skin/chemistry , Smoke/adverse effects , Nicotiana , Tobacco Smoke Pollution/adverse effects , Tobacco Smoke Pollution/analysisABSTRACT
Different a n tipollution products have recently irrupted the market to answer current health concerns related to air contamination. Thus, the development of methodologies for the appropriate evaluation of the efficacy of these products is needed. In this study, an appropriate analytical methodology has been developed and validated for the evaluation of the effectiveness of antipollution cosmetic products against the dermal absorption of different hazardous air pollutants (HAPs). In vitro vertical Franz diffusion cells and Strat-M® as human skin simulants have been used to assess the effectivity of antipollution cosmetic products. An exposition chamber, with a fixed and constant concentration of HAPs, including benzene, toluene, ethylbenzene, and xylene isomers, chlorobenzene, nitrobenzene, haloalkanes, and polycyclic aromatic hydrocarbons, has been designed and made to simulate contaminated atmospheres. The efficacy of antipollution cosmetic products has been evaluated using a multi-pollutant approach, representing a more stringent situation. Diffusion parameters, including flux and lag time, have been calculated for HAPs in the presence of cosmetic samples, using 2 mg product per cm2, and in control tests. The behavior of HAPs followed Fick's first law, allowing the calculation of diffusion parameters. Antipollution effectiveness is demonstrated by statistical evaluation of the diffusion parameters obtained for controls and cosmetics samples. So, a reduction in flux values and an increase in lag times imply an appropriate antipollution effectiveness.
Subject(s)
Air Pollutants , Cosmetics , Air Pollutants/analysis , Humans , Skin/chemistryABSTRACT
A procedure has been developed for the determination of third-generation synthetic cannabinoids in oral fluid samples by using a semi-automated microextraction by packed sorbent (MEPS) procedure and gas chromatography-mass spectrometry (GC-MS) determination. Five synthetic cannabinoids were employed as model compounds 5F-ADB, MMB-CHMICA, THJ-2201, CUMYL-4CN-BINACA and MDMB-CHMCZCA. The most adequate operative conditions for MEPS were evaluated giving quantitative recoveries, from 89 to 124%, in synthetic and field saliva samples spiked with 125 and 250 µg/L of the studied cannabinoids, with the exception of MDMB-CHMCZCA in field saliva samples that provided slightly lower recoveries from 62 to 66%. A high sensitivity was obtained for the proposed MEPS-GC-MS procedure with limits of detection from 10 to 20 µg/L. The obtained results demonstrate the high potential of MEPS-GC-MS combination for semi-automated, selective and sensitive determination of synthetic cannabinoids in oral fluid samples.
Subject(s)
Cannabinoids , Illicit Drugs , Cannabinoids/analysis , Gas Chromatography-Mass Spectrometry , Saliva/chemistryABSTRACT
This review focuses on the existing analytical procedures for the determination of new psychoactive substances (NPS) in biological fluids by chromatographic methods. Direct analysis of samples is scarcely employed and most proposed methodologies include a sample pre-treatment in order to remove matrix interferents and, in some cases, pre-concentrate extracts. Current extraction methods for NPS determination in plasma/serum, urine, and oral fluids have been widely discussed, such as liquid-liquid, solid-phase, and micro extraction approaches, highlighting the advantages and drawbacks of the proposed extraction methodologies. Regarding microextraction approaches, techniques like microextraction by packed sorbent, solid-phase microextraction, miniaturized solid phase extraction, and dispersive liquid-liquid extraction have been proposed for NPS determination in biological fluids with reliable analytical results.
Subject(s)
Body Fluids/chemistry , Clinical Chemistry Tests/methods , Psychotropic Drugs/analysis , Chromatography , Clinical Chemistry Tests/standards , Clinical Chemistry Tests/trends , Humans , Liquid Phase Microextraction , Liquid-Liquid Extraction , Psychotropic Drugs/blood , Psychotropic Drugs/urine , Saliva/chemistry , Solid Phase Extraction , Solid Phase Microextraction , Specimen Handling/standardsABSTRACT
3',4'-methylenedioxy-2,2-dibromobutyrophenone has been identified and fully characterized in a sample obtained from an anonymous consumer acquired as ketamine through the Internet market. The substance has been deeply characterized by using standard and high performance analytical techniques such as: attenuated total reflectance-infrared spectroscopy, gas chromatography-mass spectrometry, high-resolution mass spectrometry, elemental analysis, and nuclear magnetic resonance, including 1H, 13C, distortionless enhancement by polarization transfer, two dimensional homonuclear 1H-1H correlation spectroscopy, and 1H-13C heteronuclear single-quantum correlation spectra. 3',4'-methylenedioxy-2,2-dibromobutyrophenone is a precursor or intermediate in the synthesis of several synthetic cathinone derivatives, such as pentylone and methylenedioxy pyrovalerone. It is expected that 3',4'-methylenedioxy-2,2-dibromobutyrophenone does not act as psychoactive substance through disruption nor dysregulation of central and peripheral nervous systems, due to the absence of the characteristic amine group of cathinone derivatives. Although it cannot be considered a trend in new psychoactive substances consumption, the presence in the market and the unknown toxicity of this substance makes it a relevant fact.
Subject(s)
Alkaloids/chemistry , Butyrophenones/chemistry , Counterfeit Drugs , Designer Drugs/chemistry , Psychotropic Drugs/chemistry , Chromatography, Liquid , Gas Chromatography-Mass Spectrometry , Humans , Illicit Drugs/chemistry , Internet , Ketamine , Magnetic Resonance Spectroscopy , Spectroscopy, Fourier Transform InfraredABSTRACT
A direct procedure based on thermal desorption-gas chromatography-tandem mass spectrometry (TD-GC-MS-MS) was developed for the fast extraction of seven polychlorinated biphenyls (PCBs) from sediments and soils. PCBs were directly extracted, from 20 to 75â¯mg of sample, without any chemical pre-treatment or use of organic solvents, after the addition of 10 µL internal standard (PCB 195) in acetone. Sample treatment was totally automated. PCBs were extracted at 250⯰C for 20â¯min, using a helium flow and the PCBs were trapped in a cryogenic Tenax trap at -10⯰C. After that, analytes were directly desorbed at 270⯰C and introduced to the GC-MS-MS system. Recoveries were established using spiked soil and sediment from 2.5 to 50â¯ngâ¯g-1, obtaining values from 74 to 127%. The limits of quantification were from 1.0 to 1.7â¯ngâ¯g-1 for soil and from 0.3 to 0.4â¯ngâ¯g-1 for sediments, respectively. Precision, assessed as the relative standard deviation (RSD), was lower than 8 and 11% for sediment and soil analysis, respectively, except for PCB-28 in soil samples which provided a RSD of 18%. Certified reference material and field samples were analysed by the proposed TD-GC-MS-MS method. Results were compared by a paired samples Student's t-test with those obtained by a reference extraction procedure based on pressurized solvent extraction, followed by stir bar sorptive extraction, being statistically comparable (αâ¯=â¯0.05). A comprehensive greenmetric evaluation of the proposed method was carried out, having the TD extraction a negligible environmental impact as compared to conventional extraction procedures.
Subject(s)
Gas Chromatography-Mass Spectrometry/methods , Geologic Sediments/chemistry , Polychlorinated Biphenyls/analysis , Soil/chemistry , Tandem Mass Spectrometry/methods , Temperature , Humans , Reference Standards , Reproducibility of Results , Soil Pollutants/analysis , Solvents/chemistryABSTRACT
A simple procedure based on microextraction by packed sorbent (MEPS) has been proposed for the extraction of dichloropane in oral fluids and its determination by ion mobility spectrometry (IMS). Extraction conditions such as type of sorbent (octyl and octadecyl silica), sample pH, number of sample loadings, and elution volume were evaluated to obtain the most appropriate values. Dichloropane was extracted from saliva samples using C8 MEPS, loading with 100⯵L sample (adjusted to pH 7) in 4 cycles, washing with 100⯵L deionized water, and eluting with 50⯵L 2-propanol in 10 cycles. The proposed MEPS procedure has been validated in terms of linearity, accuracy, and precision. A limit of detection of 30⯵gâ¯L-1 was obtained for dichloropane determination in saliva. The analysis of field and synthetic saliva samples spiked with dichloropane at concentration levels from 250 to 750⯵gâ¯L-1 provided relative recoveries between 85 and 110%, using the proposed MEPS-IMS procedure. Field oral fluid samples were collected from healthy individuals, blind-spiked from 92 to 278⯵gâ¯L-1, and analysed by IMS and gas chromatography-mass spectrometry, being the results obtained from both methods statistically comparable. Thus, the proposed MEPS-IMS procedure involves a simple, sensitive, and accurate analysis of dichloropane in saliva.
Subject(s)
Cocaine/analogs & derivatives , Gas Chromatography-Mass Spectrometry/methods , Ion Mobility Spectrometry/methods , Saliva/chemistry , Solid Phase Microextraction/methods , Cocaine/analysis , Humans , Limit of DetectionABSTRACT
A methamphetamine-based molecularly imprinted polymer (MIP) has been prepared by bulk polymerization to recognize new psychoactive substances (NPS) of the amphetamine, cathinones and 2C families in oral fluid samples, being the first precedent of a synthetized MIP for the extraction and preconcentration 32 NPS including amphetamine type substances and synthetic cathinones from oral fluids. Pre-polymerization complex and resulting materials were appropriately characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption-desorption isotherms. Appropriateness of the material for the specific recognition of the target analytes was also evaluated through computational calculations and experimentally assessed by solid phase extraction (SPE). The most appropriate SPE conditions were evaluated and recoveries of 32 different NPS were obtained, ranging from 80 to 120% with a relative standard deviation (RSD) in all cases lower than 12%. Amphetamine-related NPS were analyzed by a fast and portable methodology based on ion mobility spectrometry (IMS) and a rearguard procedure based on ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS) providing limit of detection values from 10 to 80⯵gâ¯L-1 and from 0.03 to 1.3⯵gâ¯L-1, respectively. Oral fluid samples, containing different interferents like caffeine, fluticasone and cetirizine, were spiked with 300⯵gâ¯L-1 amphetamine and subsequently analyzed, showing recoveries ranging from 81 to 115% using both methodologies. Thus, this paper shows preliminary results to demonstrate the applicability of the developed procedure which could be used with minor modifications as screening technique in on-road drug analysis.
Subject(s)
Amphetamine/analysis , Amphetamine/isolation & purification , Body Fluids/chemistry , Chemical Fractionation/methods , Molecular Imprinting , Solid Phase Extraction/methods , Adsorption , Amphetamine/chemistry , Central Nervous System Stimulants/analysis , Central Nervous System Stimulants/chemistry , Central Nervous System Stimulants/isolation & purification , Green Chemistry Technology , Humans , PolymerizationABSTRACT
A simple, quick and low cost procedure was developed for the extraction of Δ9-tetrahydrocannabinol, cannabidiol, and cannabinol from marijuana samples, based on the use of a hard-cap espresso extraction with 2-propanol. After extraction, cannabinoids were directly determined after appropriate dilution by gas-chromatography-mass spectrometry, reaching a limit of detection from 0.03 to 0.05â¯mgâ¯g-1. Extraction efficiency was evaluated by the comparison of results obtained for seized samples by the proposed method and a reference methodology based on ultrasound-assisted extraction. Moreover, ion mobility was proposed for the rapid and sensitive determination of Δ9-tetrahydrocannabinol and cannabidiol providing a quick response for the analysis of seized marijuana samples in 1â¯min, including extraction, dilution and determination.
Subject(s)
Cannabinoids/isolation & purification , Cannabis/chemistry , Chemical Fractionation/instrumentation , Cannabinoids/chemistry , Coffee/chemistry , Gas Chromatography-Mass Spectrometry , Humans , Time FactorsABSTRACT
Immunochemical methods have been consolidated during the last few years as complementary analytical strategies for chemical contaminant and residue determination. However, generation of suitable immunoreagents for small organic molecules demands adequate hapten design. In this study, fenhexamid was considered as a model compound and novel haptens were designed and synthesized in order to evaluate the influence of the linker tethering site on antibody binding properties and immunoassay parameters. Haptens were conceived with the spacer arm at different positions, while the more antigenic aromatic moiety was kept free. The synthesis of these functionalized compounds was accomplished by total construction of the molecule through several steps. This strategy afforded very high-affinity monoclonal antibodies specific of fenhexamid, with IC50 values around or below 0.1 nM. Using these novel immunoreagents, a direct competitive enzyme-linked immunosorbent assay with a remarkably low limit of detection (4 ng L-1) was developed for the determination of fenhexamid residues. The selected immunoassay was investigated in terms of trueness, precision, repeatability, and robustness. The QuEChERS extraction methodology was applied to fortified samples and recoveries between 83% and 113%, with relative standard deviations below 20%, were observed. Moreover, contaminated and blind spiked samples were measured by the developed immunoassay and by ultra-performance liquid chromatography coupled to tandem mass spectrometry, showing statistically comparable results.
Subject(s)
Amides/analysis , Antibodies, Monoclonal/chemistry , Enzyme-Linked Immunosorbent Assay , Fungicides, Industrial/analysis , Haptens/chemistry , Limit of DetectionABSTRACT
The advantages of using smart materials as immunosorbents in the analysis of complex matrices by ion mobility spectrometry (IMS) have been highlighted in this study. A novel analytical method has been proposed for the sensitive, selective, and fast determination of residues of the plant growth regulator forchlorfenuron in fruit juices. Three different monoclonal antibodies (s3#22, p2#21, and p6#41) were employed for the production of immunosorbents, based on Sepharose gel beads, which were characterized in terms of loading capacity, solvent resistance, and repeatability for its use in solid-phase extraction (SPE). Immunosorbents that were prepared with antibody p6#44 provided the best performance, with a loading capacity of 0.97 µg, a 10% (v/v) 2-propanol tolerance, and a reusability of at least eight uses. The SPE procedure involved the use of a column with 0.15 g Sepharose beads, containing 0.5 mg antibody, which was loaded to 20 mL of the sample, washed with 2 mL of water plus 2 mL of 10% (v/v) 2-propanol, and eluted with 2 mL of 2-propanol. The cleaned extract was directly analyzed by IMS, giving a limit of detection of 2 µg L-1 with a relative standard deviation of 7.6%. Trueness was assessed by the analysis of blank grape and kiwifruit juice samples spiked with forchlorfenuron concentrations from 10 to 400 µg L-1, with recoveries from 80 to 115%. The analytical performance of the proposed immunosorbent was compared with conventional extraction and cleanup methods, such as QuEChERS and C18-based SPE, giving the cleanest extracts for accurate determinations of forchlorfenuron by IMS. Graphical abstract á .