Selenium content of Argentinean infant formulae and baby foods by pseudo-cyclic instrumental neutron activation analysis coupled to Compton suppression

The selenium levels of Argentinean infant formulae and baby food were measured using the 162-keV gamma-ray of ^77mSe (t _½ = 17.4 s) by a pseudo-cyclic instrumental neutron activation analysis (PC-INAA) method in conjunction with Compton suppression spectrometry (CSS). For comparison purposes, 5 selected infant formulae were also analyzed for selenium by a radiochemical neutron activation analysis (RNAA) method. The selenium levels for three samples agreed between ±2.8 and 6.5 % while the other two differed by 12 and 17 % which could perhaps be attributed to sample inhomogeneity. The selenium content of cow milk-based infant formulae varied from 42–146 μg kg^?1 compared to 52–63 μg kg^?1 for soy-based milk formulae. In the case of baby foods, the selenium levels varied from 34 to 74 μg kg^?1. The detection limits for selenium by PC-INAA–CSS for all the samples analyzed in this work were between 8.5 and 65 μg kg^?1 depending on the major elements present in the samples, while it was 20 μg kg^?1 for the RNAA method. The expanded uncertainty (κ = 2) of the PC-INAA–CSS method was 7.0 % at the end of cycle #4 for a sample containing 73.7 μg kg^?1 selenium compared to the RNAA value of 24.2 % for a sample of 67.0 μg kg^?1 selenium content.     

Label-free optical biosensor for detection and quantification of the non-steroidal anti-inflammatory drug diclofenac in milk without any sample pretreatment

A label-free optical biosensor for detection and quantification of diclofenac in bovine milk has been developed. This was achieved by using reflectometric interference spectroscopy as detection method. In a first step, the immunosensor was developed and optimised in buffer concerning sensitivity, selectivity, stability and reproducibility. By comparing recovery rates—not only the good intra- but also the good inter-chip—reproducibility could be proven. Consequently, the assay was transferred in the more complex matrix milk. By utilising an optimised surface modification and evaluation method, matrix effects could successfully be prevented or circumvented. As a result, the developed immunosensor does not need sample pretreatment at all. By obtaining a limit of detection of 0.112 μg L^?1 (0.108 μg kg^?1), the capability of the developed biosensor is comparable or better than those of standard detection methods. Moreover, the presented biosensor reaches the range of the maximum residue limit (0.1 μg kg^?1) set by the European Union. Thus, for the first time, diclofenac was successfully quantified at relevant levels in milk by using an optical biosensor.     

A portable electrochemical magnetoimmunosensor for detection of sulfonamide antimicrobials in honey

A new electrochemical magnetoimmunosensor (EMIS) has been developed for the screening of residues of sulfonamide antimicrobials in honey samples. The immunosensor is able to detect up to ten different sulfonamide congeners at levels below the action points established in some European countries (25 μg kg^?1) after a hydrolysis step in which the sulfonamides are released from the corresponding conjugates formed in samples of this type. In spite of the complexity of the sample after the hydrolysis procedure, the EMIS could perform quantitative measurements, directly in these samples, without any additional sample cleanup or extraction step. For example, sulfapyridine, used as a reference, can be detected in hydrolyzed honey with a limit of detection (IC₉₀) of 0.1?±?0.03 μg kg^?1. Considering that the use of antibiotics for bee treatment is prohibited in the European Union, the immunosensor presented here could be an excellent screening tool. Moreover, several samples can be processed in parallel, which facilitates the analysis, reducing the necessity to use more costly confirmatory methods for just screening. As a proof of concept, a set of blind honey samples (spiked and incurred) were analyzed and the results were compared with those obtained by high-performance liquid chromatography–tandem mass spectrometry, demonstrating the potential of the EMIS as a screening tool.

SPE–LC Multi-Residue Analysis of Mebendazole and its Metabolites in Grass Carp and Shrimp

An analytical method was developed to detect the residue of mebendazole and its metabolites (hydroxymebendazole and aminomebendazole) in the muscle of grass carp and shrimp by LC–UV detection. Mebendazole and its metabolites were extracted with water and ethyl acetate, defatted with hexane, and purified with MCX solid phase extraction column. The intra- and inter-batch precision (measured by CV%) was <9.0%. The accuracy (measured by relative error, %) was <12%. The LODs were 2.5 μg kg^?1 for mebendazole and hydroxymebendazole, 5 μg kg^?1 for aminomebendazole; the LOQs were 5 μg kg^?1 for mebendazole and hydroxymebendazole, 10 μg kg^?1 for aminomebendazole. The mean recoveries of mebendazole and its metabolites from grass carp and shrimp muscle at a concentration range of 5.0–500.0 μg kg^?1 were 90.7–97.0% with relative standard deviations below 10%.     

SPE then RP-LC for Simultaneous Analysis of Cyromazine and its Metabolite Melamine in Liquid Milk and Egg

Solid-phase extraction (SPE) and reversed-phase liquid chromatography (RP-LC) have been used for simple, sensitive simultaneous analysis of cyromazine and melamine residues in liquid milk and eggs. The conditions used for SPE and LC were investigated and optimized. A combined cation-exchange–reversed-phase cartridge was used for clean-up, and an ODS (C₁₈) column (150 mm × 4.6 mm i.d., 5-μm particles) with 62:38 (v/v) 5 mm sodium lauryl sulfate (pH 3.4)–acetonitrile as mobile phase was used for RP-LC. Under the optimum conditions the method limit of detection (LOD) for both cyromazine and melamine was 6.2 μg kg^?1 for liquid milk samples, and 11.5 μg kg^?1 for egg samples. Average recovery of cyromazine and melamine from milk samples was 90.3%, RSD 4.6–5.6%, and 99.6%, RSD 3.2–4.7%, respectively. Average recovery of cyromazine and melamine from egg samples was 85.3%, RSD 1.0–4.7%, and 89.6%, RSD 3.1–5.0%, respectively. The method enables detection of melamine and cyromazine at levels as low as 20.7 μg kg^?1 in liquid milk and 38.3 μg kg^?1 in egg.     

Development of a facile sensor for the determination of Brilliant Blue FCF in beverages

A facile method was developed for the detection of Brilliant Blue FCF (BB FCF) (E133), a synthetic soluble colorant in common beverages. The method is based on a new composite of multi-walled carbon nanotube (MWCNT)-graphite oxide (GO)-room temperature ionic liquids (MWCNT/GO-RTIL) of 1-butyl-3-methylimidazolium hexafluorophosphate with high dispersibility and strong conductivity. Differential pulse stripping voltammetry (DPSV) and the MWCNT/GO-RTIL composite-modified glassy carbon electrode (GCE) were used to determine the BB FCF in this work. Under the optimum experimental conditions, the oxidation current of BB FCF was proportional to its concentration in two linear ranges, from 6.34 μg kg^?1 to 7.93 × 10² μg kg^?1 and 7.93 × 10² μg kg^?1 to 7.93 × 10³ μg kg^?1.

The detection limit was down to 3.01 μg kg^?1 at signal-to-noise ratio of 3. Also, this method has been successfully applied in the determination of BB FCF in common beverage samples, including RIO cocktail, Bacardi Breezer and Reinnbow rum dinks. The assay results of BB FCF in drink samples obtained by the proposed method were in a good agreement with the reference values detected by high performance liquid chromatography (HPLC). The proposed method provided a useful tool for the assay of BB FCF in drink samples.     

HPLC Analysis and Pharmacokinetic Study of Paeoniflorin after Intravenous Administration of a New Frozen Dry Powder Formulation in Rats

A simple and specific high performance liquid chromatographic (HPLC) method with UV detection using picroside II as the internal standard was developed and validated to determine the concentration of paeoniflorin in rat plasma and study its pharmacokinetics after an single intravenous administration of 40 mg kg^?1 paeoniflorin to Wistar rats. The analytes of interest were extracted from rat plasma samples by ethyl acetate after acidification with 0.05 mol L^?1 NaH₂PO₄ solution (pH 5.0). Chromatographic separation was achieved on an Agilent XDB C₁₈ column (250 × 4.6 mm I.D., 5 μm) with a Shim-pack GVP-ODS C₁₈ guard column (10 × 4.6 mm I.D., 5 μm) using a mobile phase consisting of acetonitrile–water–acetic acid (18:82:0.4, v/v/v) at a flow rate of 1.0 mL min^?1. The UV detection was performed at a wavelength of 230 nm. The linear calibration curves were obtained in the concentration range of 0.05–200.0 μg mL^?1 in rat plasma with the lower limit of quantification (LLOQ) of 0.05 μg mL^?1. The intra- and inter-day precisions in terms of % relative standard deviation (RSD) were lower than 5.7 and 8.2% in rat plasma, respectively. The accuracy in terms of % relative error (RE) ranged from ?1.9 to 2.6% in rat plasma. The extraction recoveries of paeoniflorin and picroside II were calculated to be 69.7 and 56.9%, respectively. This validated method was successfully applied to the pharmacokinetic study of a new paeoniflorin frozen dry power formulation. After single intravenous administration, the main pharmacokinetic parameters t _1/2, AUC_0-∞, CL_TOT, V _Z, MRT_0-∞ and V _ss were 0.739 ± 0.232 h, 43.75 ± 6.90 μg h mL^?1, 15.50 ± 2.46 L kg^?1 h^?1, 1.003 ± 0.401 L kg^?1, 0.480 ± 0.055 h and 0.444 ± 0.060 L kg^?1, respectively.     

Chemiluminescence competitive indirect enzyme immunoassay for 20 fluoroquinolone residues in fish and shrimp based on a single-chain variable fragment

A chemiluminescent competitive indirect enzyme-linked immunosorbent assay, based on a mutant single-chain variable fragment (scFv), was developed to detect a broad range of fluoroquinolones (FQs) in fish and shrimp matrices. In this study, the best scFvC4A9H1_mut2 was adopted, which showed 10-fold improved affinity to sarafloxacin (SAR), difloxacin (DIF), and trovafloxacin (TRO), while the affinity to other FQs was fully inherited from wild-type scFvC4A9H1. In the optimized generic test, scFvC4A9H1_mut2 in combination with norfloxacin–ovalbumin conjugate and horseradish peroxidase-labeled anti-c-myc 9E10 antibody showed 50 % binding inhibition (IC₅₀) at 0.12 μg kg^?1 for norfloxacin in buffer. Screening for the class of FQ antibiotics is accomplished using a simple, rapid extraction carried out with ethanol/acetic acid (99:1, v/v). This common extraction was able to detect 20 FQ residues such as s ciprofloxacin (CIP), danofloxacin, DIF, enoxacin, enrofloxacin (ENR), fleroxacin, amifloxacin, flumequine, levofloxacin, lomefloxacin hydrochloride, marbofloxacin, norfloxacin (NOR), ofloxacin, orbifloxacin, pazufloxacin, pefloxacin-d5 (PEF), prulifloxacin, SAR, sparfloxacin, and TRO in fish and shrimp. The limit of detection (LOD) for NOR was 0.2 μg kg^?1 and the LODs for CIP and ENR were all <0.2 μg kg^?1. Values of LODs inferred from the cross-reactivity data will range from approximately 0.23 μg kg^?1 for PEF to 2.1 μg kg^?1 for TRO. Field fish and shrimp samples were analyzed and compared to the results obtained from liquid chromatography tandem mass spectrometric method. All five instances (from 0.25 to 15.6 μg kg^?1) in which FQs were present at concentrations near or above the assay LOD were identified as positive by the newly developed assay, demonstrating the usefulness of this assay as a screening tool.

Determination of twelve herbicides in tobacco by a combination of solid–liquid–solid dispersive extraction using multi-walled carbon nanotubes, dispersive liquid-liquid micro-extraction, and detection by GC with triple quadrupole mass spectrometry

We report on a method for the determination of twelve herbicides using solid–liquid–solid dispersive extraction (SLSDE), followed by dispersive liquid-liquid micro-extraction (DLLME) and quantitation by gas chromatography with triple quadrupole mass spectrometric detection. SLSDE was applied to the extraction of herbicides from tobacco samples using multi-walled carbon nanotubes (MWCNTs) as clean-up adsorbents. The effect of the quantity of MWCNTs on SLSDE, and of type and volume of extraction and disperser solvents and of salt effect on DLLME were optimized. Good linearity is obtained in the 5.0 - 500 μg kg^?1 concentration range, with regression coefficients of >0.99. Intra-day and inter-day repeatability, expressed as relative standard deviations, are between 3 and 9 %. The recoveries in case of herbicide-spiked tobacco at concentration levels of 20.0, 50.0 and 100.0 g kg^?1 ranged from 79 to 105 %, and LODs are between 1.5 and 6.1 μg kg^?1. All the tobacco samples were found to contain butralin and pendimethalin at levels ranging from 15.8 to 500.0 μg kg^?1.

Determination of Pyrethroid Residues in Pork Muscle by Immunoaffinity Cleanup and GC-ECD

A method was developed to determine six pyrethroids (tau-fluvalinate, fenpropathrin, λ-cyhalothrin, cyfluthrin, α-cypermethrin and deltamethrin) in pork muscle by immunoaffinity column cleanup and gas chromatography-electron capture detection. Spiked pork muscle samples at 5, 20, 50 μg kg^?1 were extracted with petroleum spirit-diethyl ether (1:1, v/v). Fat was eliminated by liquid–liquid partition between acetonitrile and petroleum spirit. An immunoaffinity column (IAC) was used for further cleanup. The IAC column was prepared by coupling the polyclonal antibodies to the protein A sepharose gel and the resulting affinity gel columns were sufficiently stable for multiple reuse. Target compounds were adsorbed at pH 7.4 and after extensive washing, eluted with 3 mL methanol. Recoveries of the six pyrethroids were typically >70%. The detection limit was 2 μg kg^?1 for λ-cyhalothrin and α-cypermethrin and 5 μg kg^?1 for cyfluthrin, deltamethrin, fenpropathrin and tau-fluvalinate. Repeat analyses of pork muscle samples showed good repeatability. The method was applied to detect residues in meat samples.     

Determination of reference interval values for inorganic elements in whole blood samples of humans and laboratory animals by X-ray fluorescence spectrometry

Inorganic elements are responsible for essential bodily functions, such as osmotic regulation, cardiac frequency and contractibility, blood clotting and neuromuscular excitability. The determination of inorganic elements in corporeal fluids such as blood, serum, plasma and urine is used as a monitor for a part or the whole organism; their values, then, are compared with reference interval values. In this study, the energy dispersive X-ray fluorescence spectrometry (EDXRF), applying the Fundamental Parameters method, for the determination of inorganic elements in whole blood samples from humans and laboratory animals, was used. Peripheral blood samples were collected and, before coagulation, 100 μL of sample were deposited onto Whatman No. 41 filter paper and dried, using infrared spotlight. The reference interval values for healthy Brazilian population of Na were found to be 1,788–1,826 μg g^?1, of Mg 63–75 μg g^?1, of P 602–676 μg g^?1, of S 1,519–1,718 μg g^?1, of Cl 2,743–2,867 μg g^?1, of K 1,508–1,630 μg g^?1, of Ca 214–228 μg g^?1, of Fe 170–184 μg g^?1, of Cu 4–6 μg g^?1 and of Zn 1–3 μg g^?1. The reference interval values for golden hamster (Mesocricetus auratus) of Na were found to be 1,714–1,819 μg g^?1, Mg 51–79 μg g^?1, P 970–1,080 μg g^?1, S 1,231–1,739 μg g^?1, Cl 2,775–2,865 μg g^?1, of K 1,968–2,248 μg g^?1, of Ca 209–257 μg g^?1, of Fe 145–267 μg g^?1, of Cu 4–6 μg g^?1 and of Zn 3–5 μg g^?1. A comparative study between EDXRF and instrumental neutron activation analysis data was carried out and the results for both techniques are statistically equal (α = 0.05). The results contribute for the establishment of reference interval values for Na, Mg, P, S, Cl, K, Ca, Cu and Zn in the healthy Brazilian population and the referred laboratory animal species.     

An inter-laboratory validation of a multiplex dipstick assay for four classes of antibiotics in honey

In this paper, we report the inter-laboratory validation (ILV) of a recently developed indirect competitive multiplex dipstick (Bee4sensor®) which is capable of the simultaneous detection of residues of some of the most frequently detected antibiotic residues in honey: sulfonamides, tylosin, fluoroquinolones and chloramphenicol. The multi-sensor dipstick can be interpreted via visual observation or by an instrumental measurement of four test lines. Statistical analysis of the ILV data demonstrated that the multi-sensor can reliably detect the presence of sulfathiazole at 25 μg kg^?1 and tylosin at 10 μg kg^?1, which fully meet the ‘recommended concentrations’ of the EU. Ciprofloxacin and chloramphenicol can be detected at 25 and 5 μg kg^?1 in honey, respectively. Whilst the concentration for chloramphenicol is above the EU minimum required performance limit of 0.3 μg kg^?1, this part of the multiplex test may still be of use to both the industry and enforcement authorities, to provide an early warning of contaminated honey. The estimated false-negative and false-positive rates for this easy-to-use and robust assay were less than 5 %.     

LC Determination of Chloramphenicol in Honey Using Dispersive Liquid–Liquid Microextraction

A novel method, dispersive liquid–liquid microextraction coupled with liquid chromatography-variable wavelength detector (LC-VWD), has been developed for the determination of chloramphenicol (CAP) in honey. A mixture of extraction solvent (30 μL 1,1,2,2-tetrachloroethane) and dispersive solvent (1.00 mL acetonitrile) were rapidly injected by syringe into a 5.0 mL real sample for the formation of cloudy solution, the analyte in the sample was extracted into the fine droplets of C₂H₂Cl₄. After extraction, phase separation was performed by centrifugation and the enriched analyte in the sedimented phase was determined by LC-VWD. Some important parameters, such as the kind and volume of extraction solvent and dispersive solvent, extraction time, sample solution pH, sample volume and salt effect were investigated and optimized. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 3 to 2,000 μg kg^?1 for target analyte. The enrichment factor for CAP was 68.2, and the limit of detection (S/N = 3) were 0.6 μg kg^?1. The relative standard deviation (RSD) for the extraction of 10 μg kg^?1 of CAP was 4.3% (n = 6). The main advantages of method are high speed, high enrichment factor, high recovery, good repeatability and extraction solvent volume at μL level. Honey samples were successfully analyzed using the proposed method.     

Use of a Headspace Solid-Phase Microextraction-Based Methodology Followed by Gas Chromatography–Tandem Mass Spectrometry for Pesticide Multiresidue Determination in Teas

This study reports on the development of a fast and efficient method based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography–tandem mass spectrometry (GC–MS/MS) for simultaneous analysis of 128 volatile or semi-volatile pesticide residues belonging to nine classes of pesticides. The important factors related to HS-SPME performance were optimized; these factors include fiber types, water volume, ion strength, extraction temperature, and extraction time. The best extraction conditions include a PDMS/DVB fiber, and analytes were extracted at 90 °C for 60 min from 1 g of tea added to 5 mL of 0.2 g mL^?1 NaCl solution. The methodology was validated using tea samples spiked with pesticides at three concentration levels (10, 50, and 100 μg kg^?1). In green tea, oolong tea, black tea, and puer tea, 82.8, 88.3, 79.7, and 84.3% of the targeted pesticides meet recoveries ranging from 70 to 120% with a relative standard deviation of?≤?20%, respectively, when spiked at a level of 10 μg kg^?1. Limits of quantification in this method for most of the pesticides were 1 or 5 μg kg^?1, which are far below their maximum residue limits prescribed by EU. The optimized method was employed to analyze 30 commercial samples obtained from local markets; 17 pesticide residues were detected at concentrations of 2–452 μg kg^?1. Chlorpyrifos was the most detected pesticide in 80% of the samples, and the highest concentration of dicofol (452 μg kg^?1) was found in a puer tea. This is the first time to find that the optimized extraction temperature for pesticide residues is 90 °C, which is much higher than other reported HS-SPME extraction conditions in tea samples. This developed method could be used to screen over one hundred volatile or semi-volatile pesticide residues which belong to multiple classes in tea samples, and it is an accurate and reliable technique.     

Analysis of Deoxynivalenol,Nivalenol, Zearalenone in Food by LC–APCI–MS

The detection of mycotoxins is an important task for analytical analysis, as they are a source of contaminants in foods today. The very small amounts of toxic mycotoxins (zearalenone, deoxynivalenol) make it important to determine the most reliable analytical methods. There are several options for the detection of mycotoxins, LC–API–MS techniques being the most common ones. The aim of the present determination is to give an overview on the application of LC–(API)-MS in the analysis of frequently occurring and highly toxic mycotoxins, such as deoxynivalenol, nivalenol and zearalenone, in organic foods. The limits of these three toxins in foods are very low: deoxynivalenol 1,250 μg kg^?1, nivalenol 0.9 μg kg^?1 of body weight, zearalenone 100 μg kg^?1.     

Optimized solid phase extraction based on diethyldithiocarbamate-coated Fe3O4 magnetic nanoparticles followed by ICP-OES for determination of Cd(II) and Ni(II) in rice and water samples

In the present study, application of Fe₃O₄ magnetic nanoparticles (MNPs) coated with diethyldithiocarbamate as a solid-phase sorbent for extraction of trace amounts of cadmium (Cd²⁺) and nickel (Ni²⁺) ions by the aid of ultrasound was investigated. The analytes were determined by inductively coupled plasma-optical emission spectroscopy. Fe₃O₄ MNPs were prepared by solvothermal method and characterized with dynamic light scattering, scanning electron microscope and X-ray diffraction. Response surface methodology was used for optimization of the extraction process and modeling the data. The optimal conditions obtained were as follows: chelating agent, 1.2 g L^?1; pH, 6.13; sonication time, 13 min and Fe₃O₄ MNPs, 10.3 mg. The calibration curves were linear over the concentration range of 1–1,000 μg L^?1 for Cd²⁺ and 2.5–1,000 for Ni²⁺ with the determination coefficients (R ²) of 0.9997 and 0.9995, respectively. The limits of detection were 0.27 μg L^?1 for Cd²⁺ and 0.76 μg L^?1 for Ni²⁺. The relative standard deviations (n = 7, C = 200 μg L^?1) for determination of Cd²⁺ and Ni²⁺ were 2.0 and 2.7 %, respectively. The relative recoveries of the analytes from tap, river and lagoon waters and rice samples at the spiking level of 10 μg L^?1 were obtained in the range of 95–105 %.     

Simultaneous Determination of Five Major Compounds in Polygonum cuspidatum by HPLC

An RP-HPLC method was developed for the first time to simultaneously determine five major compounds in Polygonum cuspidatum, namely resveratrol, polydatin, anthraglycoside B, emodin and physcion with UV detection at 306 nm. The column was an Agilent Zorbax SB-C₁₈ (250 × 4.6 mm i.d., 5 μm). The separation was carried out with a gradient program. The mobile phase was acetonitrile–water (containing 0.1% formic acid) at a flow rate of 1.0 mL min^?1. The standard curve was rectilinear in the range of 2.04–62.96 μg mL^?1 (r = 0.9998) for resveratrol, 20.13–239.7 μg mL^?1 (r = 0.9998) for polydatin, 7.19–71.92 μg mL^?1 (r = 1.0000) for anthraglycoside B, 2.68–83.68 μg mL^?1 (r = 0.9998) for emodin and 0.60–14.37 μg mL^?1 (r = 0.9997) for physcion. The recoveries of the markers were 96.0, 106.5, 97.8, 97.9 and 98.1%, respectively. The relative standard deviation of intra-day and inter-day were less than 5.0 and 2.3%. This method was simple, accurate and reproducible. The developed method was successfully applied to analyze five compounds in P. cuspidatum of 20 commercial brands.     

Determination of Chlorantraniliprole Residues in Corn and Soil by UPLC�CESI�CMS/MS and Its Application to a Pharmacokinetic Study

A rapid, highly sensitive, and selective method was developed for the determination of the insecticide chlorantraniliprole (CAP) in corn and soil using ultra-performance liquid chromatography?Ctandem mass spectrometry (UPLC?CMS/MS). Samples were extracted with acetonitrile, and aliquots were cleaned with solid-phase extraction cartridges. Two precursor-product ion transitions for CAP were measured and evaluated to provide maximum confidence in the results. Average recovery for soil, corn grain, and corn straw at different levels (5 or 10, 40, and 100 ??g kg^?1) ranged from 74.9 to 97.5%, with intra-day relative standard deviation (RSD) values of 1.9?C11.3% and inter-day RSD values of 4.7?C10.4%. Coefficients of determination (R ²) of 0.9988 or higher were achieved for CAP in soil, corn grain, and corn straw matrix calibration curves, from 5 to 1,000 ??g L^?1. The CAP limits of quantitation in soil, corn grain, and straw were determined to be 5, 10, and 10 ??g kg^?1, respectively, which were much lower than the maximum residue levels established by the Environmental Protection Agency of United States. UPLC?CMS/MS was used to determine the CAP residues in real corn and soil for studies on their dissipation. The trial results showed that the half-lives of CAP changed from 12.6 to 23.1 days in soils and ranged from 4.9 to 5.4 days in corn straws in the districts of Henan and Shandong, and the average levels of CAP residues in corn grains were all <0.01 mg kg^?1 with a harvest withholding period of 180 days.     

Immunosensor for electrodetection of the C-reactive protein in serum

Epidemiological studies have demonstrated an association between the risk of cardiovascular events and increasing C-reactive protein (CRP) concentration. This paper reports the development of an immunosensor for the assessment of the cardiovascular process using anti-C-reactive protein antibody immobilized onto a gold-printed screen electrode. Positive and negative human sera were successfully evaluated using electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and atomic force microscopy (AFM). EIS results show that, after the incubation with positive serum for myocardial infarction, the resistance increased about two times in relation to the negative serum. A linear range from 6.25 to 50 μg mL^?1 and detection limit of 0.78 μg mL^?1 using DPV were obtained. The immunosensor developed for the CRP detection using gold electrode revealed efficacy and a potential use for the diagnosis and monitoring of the progression of cardiovascular diseases.     

Determination of Chloramphenicol Residues in Foods by ELISA and LC-MS/MS Coupled with Molecularly Imprinted Solid Phase Extraction

The combination of molecularly imprinted solid-phase extraction (MISPE) with ELISA and LC-MS/MS was developed for the detection of chloramphenicol (CAP) in honey samples. Significant recoveries of 99.1 ± 7.1 and 98.8 ± 8.2% were obtained for intra- and inter-assay determination by ELISA determination, respectively. The limit of detection of CAP was 0.034 μg kg^?1 and the limit of quantification was 0.046 μg kg^?1. Determination and validation of CAP by using LC-MS/MS were performed following the same extraction and purification process as for the ELISA. The results demonstrated that the CAP samples purified by using MISPE were simultaneously applicable to analysis by ELISA and LC-MS/MS.