Residues In Food Samples Research Articles

Development of Immuno-Based Methods for Detection of Melamine

A competitive indirect enzyme-linked immunosorbent assay (ELISA) and a colloidal gold-based immunochromatographic assay (CGIA) using monoclonal antibodies (mAbs) were developed for the detection of melamine. Under optimum conditions, IC50 value was 8 and 8.3 ng/mL for two mAbs (2H9 and 1B12), respectively. The ELISA kit based 1B12 showed detection limit of 1.908 ng/mL, 2.125 and 4.154 ng/mg for milk, milk powder and animal feed samples, respectively; while that of 2H9 exhibited detection limit of 5.210 ng/mL, 5.748 and 5.460 ng/mg for the same products, respectively. No cross-reactivity was found from the other tested compounds. Milk, milk powder and animal feed samples spiked with concentration range from 0 to 500 ng/mL were analyzed by the established ELISA. Acceptable recovery rates of 84.74–104.94, 84.52–104.05 and 83.3–94.67 % were obtained for milk, milk powder and animal feed samples, respectively. The optimized CGIA-based 2H9 was utilized in the detection of melamine in milk, milk powder and animal feeds, with detection limit of 100 ng/mL for milk, 100 ng/mg for milk powder and 200 ng/mg for feeds, respectively. The ELISA and CGIA procedures established in this study allow on-site screening of melamine residues in food samples.

Rapid method based on immunoassay for determination of paraquat residues in wheat, barley and potato

The detection of bipyridine herbicides residues in food samples is hampered due to their particular physico-chemical features, which requires the application of specific extraction and analytical procedures, which disqualifies them from being incorporated into the multi-residue methods (MRMs). There is a need for alternative robust and efficient analytical screening methods, and in this respect, we present here a fast and reliable immunochemical analytical procedure for the detection of paraquat (PQ) residues in food samples, particularly potato, barley and wheat. The procedure involves the extraction with 1 N HCl:MeOH at 80 °C, followed by centrifugation and filtration, and the extracts can be directly measured by a microplate-based ELISA without any other sample treatment or clean-up, except from buffering the solution and adjusting the pH. Selective polyclonal antibodies, were raised against N-(4-carboxypent-1-yl)-N′-methyl bipyridilium acid (hapten PQ1), and used to establish a high sensitive immunochemical analytical assay, able to measure simultaneously many samples. Under these conditions the accuracy is very good, with almost quantitative recoveries. The non-specific interferences caused by the matrix are negligible for the case of potato and wheat, while for barley it is necessary to further dilute the extract or using a negative certified extract to build the standard calibration curve. The method of extraction consisted in acidic extraction and after a dilution is able to be measured. The analysis method results simply, achieving good detectabilities. The limits of detection (LODs) achieved were between 0.037 ± 0.01 μg kg−1 in wheat, 0.71 ± 0.3 μg kg−1 in barley and 0.56 ± 0.10 μg kg−1 in potatoes, values that are far below the Maximum Residue Level (20 μg kg−1) established by the EU policies for paraquat residues in these foodstuff products. The results demonstrate the high potential of these methods as screening tools for food safety and inspection controls.

Direct determination of ampicillin and amoxicillin residues in food samples after aqueous SDS extraction by micellar liquid chromatography with UV detection

A simple, sensitive and rapid micellar HPLC method was optimized and validated for the analysis of amoxicillin and ampicillin residues in food samples. Analytical separation was performed in less than 7 min using a RP C18 column with UV detection at 220 nm and a micellar solution of 0.05 M sodium dodecyl sulphate, 5% 1-propanol and 0.3% triethylamine in 0.02 M phosphoric acid buffered at pH 5 as the mobile phase. The flow rate was 1 mL min−1 and the effluent was monitored at 220 nm. The micellar method was successfully applied to quantitatively determine amoxicillin and ampicillin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, kidney and eggs. The method was fully validated in accordance with ICH guidelines. Linearity was in the range 0.4–20 μg mL−1 for each drug and the percentage recoveries of both drugs ranged from 95.5 to 102.3% for amoxicillin and 95.6 to 101.7% for ampicillin. High extraction efficiency of amoxicillin and ampicillin was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. An aqueous solution of SDS surfactant only was used in extraction. No organic solvent was used during the pretreatment step. Hence, it is considered an interesting technique for “green” chemistry.

Coulombimetric immunosensor for paraquat based on electrochemical nanoprobes

A new electrochemical immunosensor has been developed to detect paraquat (PQ) pesticide residues in food samples. The immunosensor presented uses electrochemical nanoprobes prepared by labeling the PQ specific antibodies with CdS nanoparticles (CdSNP) and antigen biofunctionalized magnetic μ-particles. Electrochemical measurements are performed using graphite composite electrodes (GECs). After the immunochemical reaction, the CdSNP are dissolved and the metal ions released are reduced at the electrode and read in the form of current or charge signal, by the well-known anodic stripping technique. Due to the amplification effect produced by the CdSNP on the amperometric/coulombimetric signal, a very high detectability is reached. Thus, PQ can be detected with an IC50current of 0.18±0.31μgL−1 (in PBST). The immunosensor has been implemented in analyzing PQ residues in potato samples. Combined with a suitable extraction procedure PQ can be detected with a LOD current of 1.4μgkg−1, far below the maximum residue limit (MRL, 20μgkg−1) established by the EU for this pesticide in most crops. Likewise, the working range was in the interval between 3.08 and 67.76μgkg−1. Preliminary experiments demonstrate that the immunosensor presented here could be used as screening tool to distinguish between compliant and non-compliant food samples.

A Label-Free Silicon Quantum Dots-Based Photoluminescence Sensor for Ultrasensitive Detection of Pesticides

Sensitive, rapid, and simple detection methods for the screening of extensively used organophosphorus pesticides and highly toxic nerve agents are in urgent demand. A novel label-free silicon quantum dots (SiQDs)-based sensor was designed for ultrasensitive detection of pesticides. This sensing strategy involves the reaction of acetylcholine chloride (ACh) with acetylcholinesterase (AChE) to form choline that is in turn catalytically oxidized by choline oxidase (ChOx) to produce betaine and H2O2 which can quench the photoluminescence (PL) of SiQDs. Upon the addition of pesticides, the activity of AChE is inhibited, leading to the decrease of the generated H2O2, and hence the PL of SiQDs increases. By measuring the increase in SiQDs PL, the inhibition efficiency of pesticide to AChE activity was evaluated. It was found that the inhibition efficiency was linearly dependent on the logarithm of the pesticides concentration. Consequently, pesticides, such as carbaryl, parathion, diazinon, and phorate, were determined with the SiQDs PL sensing method. The lowest detectable concentrations for carbaryl, parathion, diazinon, and phorate reached 7.25 × 10(-9), 3.25 × 10(-8), 6.76 × 10(-8), and 1.9 × 10(-7) g/L, respectively, which were much lower than those previously reported. The detecting results of pesticide residues in food samples via this method agree well with those from high-performance liquid chromatography. The simple strategy reported here should be suitable for on-site pesticides detection, especially in combination with other portable platforms.

A label-free impedimetric immunosensor for detection of 1-aminohydantoin residue in food samples based on sol–gel embedding antibody

A novel label-free impedimetric immunosensor for detection 1-aminohydantoin (AHD) was first constructed by the silica sol–gel immobilization of monoclonal antibody against 1-aminohydantoin antibody (AHD-McAb) on the surface of glassy carbon electrode (GCE). The electrochemical impedance spectroscopy of ferricyanide was used as a marker to probe the interface and as a redox probe to determinate AHD. The effect of operational parameters, such as amount of immobilized AHD-McAb, pH, incubation time, and incubation temperature, has been explored for the optimum analytical performance of the impedimetric immunosensor. Under the optimized conditions, the change in impedance was proportional to AHD concentrations in the range of 2.0–1.0 × 103 ng/mL (r = 0.9990) with the detection limit of 2.0 ng/mL. The specificity, reproducibility, stability, and accuracy of the proposed impedimetric immunosensor were also evaluated. In addition, the proposed immunosensor was successfully applied for the determination of AHD in food samples using the standard adding method with recoveries of 93.7–104.9%. The results obtained by the proposed immunosensor corroborate very well with the method of HPLC–MS/MS for the determination of AHD in food samples.

Simultaneous Determination of Multiple (Fluoro)quinolone Antibiotics in Food Samples by a One-Step Fluorescence Polarization Immunoassay

This paper describes a rapid one-step fluorescence polarization immunoassay (FPIA) for the simultaneous determination of multiple (fluoro)quinolone antibiotics (FQs) in food samples. Several fluorescent tracers were synthesized and evaluated in the FPIA method based on a broad-specificity of monoclonal antibodies toward FQs. The heterogeneous tracer, SAR-5-FAM, was considered as the optimal choice to prepare the immunocomplex single reagent, which allows a rapid and sensitive displacement reaction by addition of analytes. Optimized single-reagent FPIA exhibited broad cross-reactivities in the range of 7.8-172.2% with 16 FQs tested and was capable of determining most FQs at the level of maximum residue limits. Recoveries for spiked milk and chicken muscle samples were from 77.8 to 116%, with relative standard deviation lower than 17.4%. Therefore, this method could be applicable in routine screening analysis of multiple FQ residues in food samples.

Determination of Triazines Residues in Food Samples Using Dummy Molecularly Imprinted Solid Phase Extraction Based on Molecular Simulation

Determination of Triazines Residues in Food Samples Using Dummy Molecularly Imprinted Solid Phase Extraction Based on Molecular Simulation

An ultrasensitive chemiluminescent ELISA for determination of chloramphenicol in milk, milk powder, honey, eggs and chicken muscle

A competitive, direct, chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA) for chloramphenicol (CAP) residues in milk, milk powder, honey, eggs and chicken muscle has been developed. The method gave a detection limit of 0.7 ng L−1 and a linear range of 2.1–92.4 ng L−1, with the IC50 of 13.6 ng L−1 under optimal conditions, dramatically better than any previously reported ELISA method for CAP detection. Spiked at levels of 5–60 ng L−1 in different food samples, recoveries were in the range of 72.1–116.0%, with coefficient of variations of 4.2–20.2%. In a study of incurred residues, the chicken muscle samples diluted 5-, 10- and 20-fold, results obtained by CL-ELISA correlated well with those obtained by gas chromatography with microcell electron capture detector and traditional ELISA. The developed CL-ELISA method is, therefore, suitable for rapid screening trace CAP residues in food samples.

Application of Graphene-based Solid-Phase Extraction Coupled with Ultra High-performance Liquid Chromatography-Tandem Mass Spectrometry for Determination of Macrolides in Fish Tissues

A novel analytical protocol for the determination of five macrolides (MLs) in crucian carp tissues has been developed. Two-dimensional (2D) planar graphene powder was utilized as the solid-phase extraction (SPE) sorbent for analyte enrichment and cleanup. The target analytes were separated by ultra high-performance liquid chromatography (LC) and quantified by a triple–quadrupole linear ion trap mass spectrometer. The proposed analytical procedures were carefully optimized and validated. Average recoveries of MLs were between 81.7 and 110.5 %, which was the highest comparing with the conventional sorbents including C18 silica and multiwalled carbon nanotubes (MWCNTs). Method validation proved the feasibility of the developed nanoparticles for the quantificatation of the investigated analytes at trace levels obtaining low limit of quantitation values in the microgram per kilogram range. Good precision with coefficients of variations always lower than 10 % was obtained. The proposed method has been successfully applied to the analysis of ML in several aquaculture product samples, indicating that graphene was a potential SPE sorbent for the enrichment of trace residues in food samples.

Development of a Coulombimetric immunosensor based on specific antibodies labeled with CdS nanoparticles for sulfonamide antibiotic residues analysis and its application to honey samples

A new electrochemical immunosensor has been developed to detect sulfonamide antibiotic residues in food samples. The immunosensor presented uses immunoreagents specifically developed for the broad recognition of the sulfonamide antibiotic family, a graphite composite electrode (GEC), biofunctionalized magnetic μ-particles and electrochemical nanoprobes prepared by labeling the specific antibodies with CdS nanoparticles (CdSNP). After the immunochemical reaction, the CdSNP are dissolved and the metal ions released are reduced at the electrode and read as in the form of current or charge signal, by the well-known anodic stripping technique. Due to the amplification effect on the amperometric/coulombimetric signal produced by the CdSNP, a high detectability can be reached. Thus, sulfapyridine (SPY), one of the most widely used sulfonamide congeners, can be detected in buffer with an IC50current of 0.20±0.25μgL−1. The immunosensor has been applied to the analysis of residues of this antibiotic in honey samples. Due to the reported formation of sulfonamide–sugar conjugates in this type of matrix, honey samples are first hydrolyzed in acidic media. The use of magnetic particles minimizes the matrix effect allowing to reach a detectability (LOD, limit of detection) of 0.11μgkg−1 (current measurements), far below the limits established in some countries for these types of residues in honey samples. Due to the use of magnetic racks, multiple samples can be run simultaneously. The whole analysis process can be performed in around 22min.

Determination of chloramphenicol in aquatic products by graphene-based SPE coupled with HPLC-MS/MS

An effective analytical protocol using graphene-based SPE coupled with HPLC-MS/MS for determination of chloramphenicol (CAP) in aquatic products has been developed. In the present work, graphene was evaluated as SPE sorbents for the analytes enrichment and clean up. The target analytes were quantified by a triple-quadrupole linear ion trap MS in multiple-reaction monitoring mode. In addition, the proposed method was validated according to Commission Decision 2002/657/EC. The calibration curve was linear over the range of 0.5-100 ng/mL. The mean values of RSD of intra- and interday ranging from 1.48 to 4.29% and from 3.25 to 7.42% were obtained, respectively. In the three fortified levels, the recoveries of CAP ranging from 92.3 to 103.4% with RSDs ≤ 5.58% were obtained. The proposed method has been successfully applied to the analysis of CAP in several aquatic product samples, indicating that graphene was a potential SPE sorbent for the enrichment of trace residues in food samples.

A gel-based visual immunoassay for non-instrumental detection of chloramphenicol in food samples

A gel-based non-instrumental immuno-affinity assay was developed for the rapid screening of chloramphenicol (CAP) in food samples with the limit of detection (LOD) of 1μgL−1. The immuno-affinity test column (IATC) consisted of a test layer containing anti-CAP antibody coupled gel, and a control layer with anti-HRP antibody coupled gel. Based on the direct competitive immuno-reaction and the horseradish peroxidase enzymatic reaction, the test results could be evaluated visually. Basically, blue color development represented the negative results, while the absence of color development represented the positive results. In this study, CAP spiked samples of raw milk, pasteurized milk, UHT milk, skimmed milk powder, acacia honey, date honey, fish and shrimp were tested. Little or none sample pretreatment was required for this assay. The whole procedure was completed within 10min. In conclusion, the gel-based immuno-affinity test is a simple, rapid, and promising on-site screening method for CAP residues in food samples, with no instrumental requirement.

Rapid detection method for nitrofuran antibiotic residues by surface-enhanced Raman Spectroscopy

Nitrofurans are a group of widely used veterinary antibiotics which have been forbidden in many countries. Surface-enhanced Raman spectroscopy (SERS) coupled with gold nanoparticles was used in this study for the rapid detection and characterization of nitrofuran antibiotics (including furadantin, furaltadone, and their mixture). Density functional theory calculations were conducted with Gaussian 03 at the B3LYP level using the 6-31G(d) basis set to analyze the assignment of vibrations. The SERS measurement of nitrofuran antibiotics has been investigated by active SERS substrate of gold nanoparticles with average size around 50 nm. The SERS qualitative analysis has been studied for furadantin and furaltadone by their characteristic SERS peaks. The peaks at 1,420 and 1,456 cm−1 could be used to discriminate between the two compounds in a mixture. The SERS peaks at 1,008 and 1,162 cm−1 were used as the index of quantitative analysis for furadantin and furaltadone, respectively. Under optimal conditions, the limit of detection could reach the level of 5 ppm. The results showed that the SERS method with gold nanoparticles is capable of identifying and characterizing furaltadone and furadantin, which is valuable to be further applied on the detection of antibiotic residues in food samples.

한국형 총식이섭취조사(Total Diet Study, TDS) 모델 확립을 위한 농약섭취수준에 대한 접근

This study was carried out to establish Korean total diet study (TDS) model for estimating pesticide residue in food samples. In addition, pesticide residues of food samples were monitored by setting the standards of established Korean total diet study model. For monitoring, first step were selection of total 102 species food samples, second step were selection of total 70 species food samples, and third step were selection of total 12 representative diet and 109 species food samples. Ninety-eight pesticides were analyzed using , GC-MS, and LC-MS/MS after QuEChERS sample preparation method. The residue levels in detected food samples were below the maximum residue limit (MRL). Establishment of the Korean total diet study model means providing safe food for consumers, secure the safety of food samples and provide ongoing information to agricultural producers about use of pesticides.

Development of an impedimetric immunosensor for the determination of 3-amino-2-oxazolidone residue in food samples

The use of furazolidone in food animals has been banned in European Union (EU) because of its carcinogenicity and mutagenicity on human health, but its continued misuse is widespread. Therefore, there is an urgent need for a simple, reliable, and rapid method for the detection of its marker residue, 3-amino-2-oxazolidinone (AOZ), in food products. In this regard, a sensitive and reliable electrochemical method was presented to detect AOZ based on a novel label-free electrochemical impedimetric immunosensor to address this need. The immobilization of monoclonal antibody against AOZ (denoted as AOZ-McAb) on the gold electrode was carried out through a stable acyl amino ester intermediate generated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydrosuccinimide (NHS), which could condense antibodies on the self-assembled monolayer (SAM). The detection of AOZ was performed by measuring the relative change in charge transfer resistance before and after AOZ and AOZ-McAb immunoreaction by electrochemical impedance spectroscopy (EIS). Under the optimized conditions, the relative change in charge transfer resistance was proportional to the logarithmic value of AOZ concentrations in the range of 20.0 to 1.0 × 10 4 ng mL −1 ( r = 0.9987). Moreover, the proposed immunosensor has a high selectivity to AOZ alone with no significant response to the metabolites of other nitrofuran antibiotics, such as 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), semicarbazide (SEM), and 1-aminohydantoin hydrochloride (AHD). This protocol has been applied to detect AOZ in food samples with satisfactory results.

Simultaneous Determination of 20 Pharmacologically Active Substances in Cow's Milk, Goat's Milk, and Human Breast Milk by Gas Chromatography–Mass Spectrometry

This paper reports a systematic approach to the development of a method that combines continuous solid-phase extraction and gas chromatography-mass spectrometry for the simultaneous determination of 20 pharmacologically active substances including antibacterials (chloramphenicol, florfenicol, pyrimethamine, thiamphenicol), nonsteroideal anti-inflammatories (diclofenac, flunixin, ibuprofen, ketoprofen, naproxen, mefenamic acid, niflumic acid, phenylbutazone), antiseptic (triclosan), antiepileptic (carbamazepine), lipid regulator (clofibric acid), β-blockers (metoprolol, propranolol), and hormones (17α-ethinylestradiol, estrone, 17β-estradiol) in milk samples. The sample preparation procedure involves deproteination of the milk, followed by sample enrichment and cleanup by continuous solid-phase extraction. The proposed method provides a linear response over the range of 0.6-5000 ng/kg and features limits of detection from 0.2 to 1.2 ng/kg depending on the particular analyte. The method was successfully applied to the determination of pharmacologically active substance residues in food samples including whole, raw, half-skim, skim, and powdered milk from different sources (cow, goat, and human breast).

QuEChERS: possibilidades e tendências no preparo de amostra para determinação multirresíduo de pesticidas em alimentos

This paper presents an updated overview of the QuEChERS multiresidue extraction method that involves initial extraction in acetonitrile, an extraction/partition step after the addition of salt, and a clean-up step utilizing dispersive solid phase extraction. QuEChERS method is nowadays the most applied extraction method for the determination of pesticide residues in food samples, providing acceptable accuracy and precision for acidic, neutral and basic pesticides.

Development of polyclonal antibody-based indirect competitive enzyme-linked immunosorbent assay for sodium saccharin residue in food samples

A sensitive and specific polyclonal antibody (PcAb)-based indirect competitive enzyme-linked immunosorbent assay (icELISA) for sodium saccharin is described. 6-Amino saccharin was coupled to carrier protein for artificial antigen by diazotisation. New Zealand white rabbits were immunised to obtain anti-sodium saccharin PcAb and then icELISA was developed. The assay showed high sensitivity and specificity to sodium saccharin, with the 50% inhibition value (IC50) of 0.243μgmL−1, workable range (IC30–IC70) of 0.050–12.8μgmL−1 and limit of detection (LOD, IC20) of 0.021μgmL−1. The average recoveries of sodium saccharin in spiked food samples were estimated ranging from 70.7% to 98.8%. A statistically significant correlation of results was obtained between this new ELISA and previously established HPLC approaches with the food-relevant sodium saccharin concentration range 0–320μgmL−1 (R2=0.9887–0.9975). These results indicated that the established ELISA was a potential and useful analytical tool for rapid determination of sodium saccharin residue in food samples.

Competitive multi-immunosensing of pesticides based on the particle manipulation with negative dielectrophoresis

In this work, we have applied particle manipulation based on negative dielectrophoresis (n-DEP) to develop rapid and separation-free immunosensing systems. Two widely used pesticides, atrazine and bromopropylate, were used as target molecules to demonstrate competitive immunosensing based on the rapid manipulation of microparticles. A suspension of the fluorescence microparticles modified with a specific antibody was injected into the n-DEP device consisting of the interdigitated microarray (IDA) electrode and indium-tin-oxide (ITO) substrate immobilized by protein conjugation with antigen. The application of 2 MHz AC voltage (16 V peak-to-peak) to the IDA forced most of the particles to form a line pattern on the upper ITO over the gaps of IDA within 60 s. In the absence of analytes, patterned microparticles were irreversibly captured on the ITO by the construction of immuno-complexes. When the microparticles bearing anti-atrazine IgG antibody were suspended in an analyte (atrazine) solution, irreversible capturing of microparticles on the ITO was inhibited because of the occupation of the binding sites of the antibodies with free-atrazine. As a result, the analyte molecules were re-dispersed from the ITO to disintegrate the line formation after turning off the voltage. We could discriminatively detect the fluorescence intensity of the captured microparticles at the designated areas from that of the uncaptured microparticles suspended in the solution. Thus, the separation steps usually required for conventional immunoassay are eliminated in the present procedure. A pre-incubation of microparticles for 3 min in an orange juice solution containing analyte allowed for the determination of the atrazine and bromopropylate concentrations with a limit of detection of 4 and 1.5 μg L −1, respectively, providing sufficient detectability to achieve international regulations regarding pesticide residues in food samples. The assay was significantly accelerated by the rapid particle manipulation with n-DEP and totally accomplished within 5 min. We also demonstrated the possibility of the simultaneous determination of two pesticide residues by using the DEP devices with two channels modified with specific competitors for atrazine and bromopropylate.