Swine Urine Research Articles

Development of a rapid and sensitive enzyme-linked immunosorbent assay to detect clonidine residues in swine urine samples

Clonidine (CLD) may be illegally used on animals because it can play the role of growth promoters. For the first time, a rapid direct competitive enzyme-linked immunosorbent assay (ELISA) was established based on polyclonal antibodies to detect CLD. The antibody showed high sensitivity, with the limit of detection (LOD) and IC50 being 0.01 and 0.056 µg/L, respectively. The specificity of the assay was evaluated by the measurement of cross-reactivity (CR) of the antibody with related compounds. Recovery rates ranged from 88% to 94%, and the coefficient of variation was below 11% for intra- and inter-assays. Highly consistent results were obtained for the urine samples by ELISA and UPLC-MS/MS method. It indicates good parallelism, accuracy and precision of the assay. The prototype kit could be advantageously used for the screening of large groups of urine samples, and has reliability even in routine application for the control of the illegal use of the drug.

The effect of pH on the efficiency of an SBR processing piggery wastewater

To treat piggery wastewater efficiently, the hydrolysis of urea (mainly derived from swine urine) in piggery wastewater with the change of sewage pH must be considered. Using activated sludge, piggery wastewater was treated in a sequencing batch reactor (SBR), and the effects of influent pH on SBR processing efficiency, sludge settle ability, and sludge activity were investigated. The results showed that a high influent pH value contributed to the improvement of the removal rate of ammonia nitrogen and reduction of the chemical oxygen demand (COD). When the influent pH was between 9.0 and 9.5, the removal rate of ammonia nitrogen was higher than 90%, and the reduction of COD from its original value was 80%. The influent pH had a greater influence on sludge concentration and sludge activity. When the influent pH increased from 7.0 to 9.5, the sludge concentration increased from 2,350 to 3,947 mg/L in the reactor, and the activities of ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) first increased and then decreased. When the influent pH was 9.0 and 8.0, the maximum values (0.48 g O2/(g MLSS/day) and 0.080 g O2/(g MLSS/day)) were reached, and the sludge settling ratio was nearly steady between 20 and 35% in each reactor.

A rabbit monoclonal antibody-based sensitive competitive indirect enzyme-linked immunoassay for rapid detection of chloramphenicol residue

A sensitive competitive indirect enzyme-linked immunoassay (ciELISA) based on a rabbit monoclonal antibody (RabMAb) against chloramphenicol (CAP) has been developed and validated in this study. After optimisation of several key physicochemical factors, such as Tween-20 percentage, pH value and ionic strength, the immunoassay showed excellent performance within the linear range of 0.18–6.37 ng mL−1, with the 50% inhibition concentration (IC50) of 1.06 ng mL−1 and the limit of detection (LOD) of 0.1 ng mL−1. In addition, the cross-reactivities of RabMAb towards chloramphenicol succinate, florfenicol and thiamphenicol were 2.09, 12.45 and 18.10%, respectively. Finally, the developed method was applied in spiked swine urine, milk and honey samples, with recoveries ranging from 71.03 to 109.62%. The result demonstrated that the developed immunoassay is a valuable method for screening and quantitation of CAP residues in real samples.

Design and performance of hybrid constructed wetland systems for high-content wastewater treatment in the cold climate of Hokkaido, northern Japan

The performance of six multistage hybrid constructed wetland systems was evaluated. The systems were designed to treat four kinds of high-content wastewater: dairy wastewater (three systems, average inflow content 2,400-5,000 mg·COD l(-1), 3-6 years of operation); pig farm wastewater, including liquid food washing wastewater (one system, 9,500 mg·COD l(-1), 3 years); potato starch processing wastewater (one system, 20,000-60,000 mg·COD l(-1), 3 years); and wastewater containing pig farm swine urine (one system, 6,600 mg·COD l(-1), 2.8 years) (COD = chemical oxygen demand). The systems contained three or four vertical (V) flow beds with self-priming siphons and surface partitions and no or one horizontal (H) flow bed (three to five beds). In some V flow beds, treated effluents were recirculated (Vr) through the inlet to improve performance. Mean annual temperature was 5-8 °C at all locations. To overcome clogging due to the high load in a cold climate, we applied a safety bypass structure and floating cover material to the V flow beds. Calculated average oxygen transfer rates (OTRs) increased proportionally with the influent load, and the OTR value was Vr > V> H. The relations of load-OTR, COD-ammonium, and a Arrhenius temperature-dependent equation enable the basic design of a reed bed system.

Preparation of stir cake sorptive extraction based on poly(4-vinylbenzoic acid-divinylbenzene) monolith and its application in sensitive determination of β-agonists in milk and swine urine samples

In this study, a new stir cake sorptive extraction (SCSE) based on poly(4-vinylbenzoic acid-divinylbenzene) (VBADB) monolith was prepared. The effect of preparation conditions of monolith on extraction efficiencies was investigated in detail. Several characteristic techniques, such as elemental analysis, infrared spectroscopy, mercury intrusion porosimetry and scanning electron microscopy were used to characterize the monolithic material. The combination of SCSE-VBADB with high-performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) detection was developed for sensitive determination of ultra-trace β-agonists in milk and swine urine samples. In order to obtain the optimal extraction conditions of SCSE-VBADB for β-agonists, several extractive parameters, including pH values and ionic strength in sample matrix, extraction and desorption time were optimized. Under the optimum conditions, the limits of detection (S/N=3) for the target analytes were 0.007–0.030μg/L in milk and 0.002–0.011μg/L in swine urine, respectively. Excellent method reproducibility was achieved in terms of intraday and interday precisions, indicated by the RSDs of both <10.0%, respectively. Finally, the proposed method was successfully used to detect β-agonists in different milk and swine urines samples. Acceptable recoveries ranged from 50.3% to 113% and 50.1% to 92.2% for milk and swine urine samples, respectively; and the RSDs for reproducibility were less than 8.0% for target analytes in all real samples.

Development of an immunochromatographic assay for rapid and quantitative detection of clenbuterol in swine urine

A lateral flow strip test was developed for quantitative detection of clenbuterol (CLE) in swine urine in a 10 min total assay time. This new quantitative system for CLE was developed based on the concept of using the ratio of the optical densities (ODs) of the test line (AT) to that of the control line (AC) to offset the inherent heterogeneity of lateral flow test strips (LFTSAT/AC) and the effect of sample matrix. Various parameters such as immunoreaction time, the concentration of analyte, reaction temperature and pH of the reactions, as well as the ionic strength were optimized in urine samples. The assay kinetics based on the immunological reactions indicated achievement of constant signal within 5–10 min of incubation depending upon the CLE concentration. Using the optimized parameters, the linear range for the quantitative detection of CLE using the LFTSAT/AC was between 100 pg/mL and 2500 pg/mL over a 10 min total assay time. The CLE LFTSAT/AC showed a half maximal inhibitory concentration (IC50) of 460 ± 60 pg/mL (n = 5) and a reliable coefficient of correlation (R2 = 0.996). The CLE test strip exhibited insignificant cross-reaction (Cr) to mabuterol, isoproterenol, salbutamol, terbutaline, brombuterol, ractopamine and bambuterol. The limit of detection (LOD) for swine urine was 220 pg/mL, and recoveries for spiked sample were 102.35% ± 7.66% at 500 pg/mL, 95.07% ± 7.14% at 1000 pg/mL and 100.65% ± 10.21% at 1500 pg/mL, respectively. The intra-and inter-assay precision at 500–1500 pg/mL CLE concentrations showed coefficients of variation (CVs) at <11%. This rapid quantitative LFTSAT/AC system for CLE in spiked urine samples exhibited a coefficient of correlation with traditional ELISA at 0.97 (N = 50). Furthermore, 96% of 90 samples gave a percent recovery of 100 ± 30%. These results indicated that the 10-min colloidal gold-based LFTSAT/AC system is adaptive, sensitive, reproducible, and comparable to traditional ELISA method with the added advantage of being easy to use, inexpensive, and requires non-skilled personnel. The LFTSAT/AC holds promise for field use an on-site detection of CLE in swine urine samples.

Ru(phen)32+ doped silica nanoparticle based immunochromatographic strip for rapid quantitative detection of β-agonist residues in swine urine

A Ru(phen)32+ doped silica nanoparticle based immunochromatographic strip was developed for the rapid and quantitative detection of five common β-agonist (salbutamol (SAL), cimbuterol, terbutaline, clenbuterol, and brombuterol) residues in swine urine. The broad spectrum monoclonal antibodies generated by immunizing BALB/c mice with salbutamol conjugated cationic bovine serum albumin. The fluorescence intensities (FIs) of the strip on the test line (FIT) and control line (FIC) were determined using a strip reader. Parameters that influenced the antibody and antigen interaction on the test strip were investigated by recording FIT and FIC values, and the concept of FIT/FIC ratio was used to offset the inherent heterogeneity of the test strips and the effect of the sample matrix. Under optimal conditions, the linear range for the quantitative detection of SAL was 0.6–5.0ng/ml with a half maximal inhibitory concentration at 1.78ng/ml. The limit of detection for real swine urine was 0.43ng/ml. The recovery rates of the intraassay for spiked urine at SAL concentrations of 0.8, 1.5, and 3.5ng/mL were 88.06%±3.75%, 95.77%±5.33%, and 94.06%±7.43%, whereas those for the interassay were 84.69%±5.0%, 95.06%±9.3%, and 88.34%±7.71%, respectively. The developed quantitative method exhibited excellent agreement with a commercially available competitive enzyme-linked immunosorbent assay kit for SAL-spiked urine samples, with a correlation of coefficient of 0.95 and a slope of 0.99 (n=36). The results indicated that the developed test strip enables sensitive, reproducible, and easily implementable screening for the rapid and quantitative detection of β-agonist residues in swine urine.

CdSe/ZnS Quantum Dots with Multi-Shell Protection: Synthesis and Application in the Detection of Ractopamine Residue in Swine Urine

CdSe/ZnS Quantum Dots with Multi-Shell Protection: Synthesis and Application in the Detection of Ractopamine Residue in Swine Urine

Rabbit Monoclonal Antibody-Based Lateral Flow Immunoassay Platform for Sensitive Quantitation of Four Sulfonamide Residues in Milk and Swine Urine

Based on the available rabbit monoclonal antibody (RabMAb), a rapid and sensitive lateral flow immunoassay (LFA) platform has been developed for quantitative detection of four sulfonamide residues(SRs) of sulfadiazine (SD), sulfathiazole (STZ), sulfapyridine (SP), and sulfamethoxazole (SMX).Within the designed LFA competitive format assay, which was based on antigen-antibody properties, the hapten conjugate N1-[4-(carboxymethyl)-2-thiazolyl] sulfanilamide linked to protein ovalbumin (TS-OVA) and goat anti-rabbit antibody were sprayed as capture and control reagents, respectively, and then the antibody was conjugated to colloidal gold particles as the detection reagent. With quantitative assessment aided by a colorimetric strip reader, the sensitivities of the established LFA method for SD, STZ, SP, and SMX were 0.91 ng mL−1, 0.10ng mL−1,0.12ng mL−1, and 2.13ng mL−1, and the half-maximum inhibition concentrations (IC50) were 5.19 ng mL−1, 1.25 ng mL−1, 0.66 ng mL−1, and 24.14 ng mL−1, respectively. The recoveries at three spiked levels (5, 20, 50 ng mL−1for SD, STZ, and SP; 20, 50, 100 ng mL−1 for SMX) were in the range of 78.02–135.10% and 76.40–137.16% for milk and swine urine, respectively. More importantly, the detection performance of the established platform was consistent with that of in-parallel LC-MS/MS analysis. In conclusion, the proposed LFA platform has showed the potential for fast, sensitive and relatively accurate quantification of four sulfonamide residues in practical uses.

Performance of six multi-stage hybrid wetland systems for treating high-content wastewater in the cold climate of Hokkaido, Japan

The performance of six multi-stage hybrid wetland systems, which were designed and constructed for treating high-content wastewater, was evaluated in the cold climate of Hokkaido, northern Japan. The systems were designed to treat four kinds of wastewater: dairy wastewater (three systems, average inflow 4.9–46.6m3d−1, average inflow content 2400–5000mgCODl−1, 2–5 years of operation); wastewater from a pig farm, including liquid food washing wastewater (one system, 4.1m3d−1, 9500mgCODl−1, 2 years of operation); wastewater from potato starch processing (one system, 5.4–13.3m3d−1, 24,000–54,000mgCODl−1, 2 years of operation); and wastewater containing pig farm swine urine (one system, 16.9m3d−1, 10,100mgCODl−1, 1 year operation). Our systems were composed of three to four vertical (V) flow beds with self-priming siphons and surface partitions and no or one horizontal (H) flow bed (total of three to five beds). In some V flow beds, treated effluents were recirculated (Vr) through the inlet to improve performance, mainly during the growing season. The total bed area was 168–2151m2. Mean annual temperature was 5–8°C at all locations. To overcome clogging due to the high load in a cold climate, we applied a safety bypass structure and floating cover material (Supersol: lightweight porous glass) to the V flow beds. The safety bypass structure and floating cover material helped to prevent clogging and freezing and maintained dry conditions and abundant growth of reeds and earthworms. The average purification rates were 70–96% for chemical oxygen demand (COD), 39–90% for total nitrogen (TN), 36–82% for NH4–N, and 70–93% for total phosphorous (TP). Calculated average oxygen transfer rates (OTRs) were 16–99gO2m−2d−1. OTRs increased in proportion to influent load, and the OTR value was Vr>V>H. Recirculating the treated effluents was expected to enhance removal of nitrogen in V flow beds mainly by a combination of nitrification and denitrification. By treating higher organic loads per area without clogging, it was possible to minimize the area and cost of treating high-content wastewater. However, more data are needed concerning load and OTR to design a more efficient multi-stage wetland system.

Sensitive determination of illegal drugs of clenbuterol and salbutamol in swine urine by capillary electrophoresis with on-line stacking based on the moving reaction boundary

The sensitive determination of clenbuterol (CLB) and salbutamol (SAL) in swine urine was developed by using capillary electrophoresis with a moving reaction boundary (MRB)-based stacking method. Under the optimum conditions, the MRB-based stacking procedure produced an improved concentration sensitivity of 70.5-fold for CLB and 24.7-fold for SAL. The improvement results in a limit of detection (LOD) of about 0.26 ng mL−1 and 0.96 ng mL−1 for CLB and SAL, respectively. The method has been successfully used for the analysis of CLB and SAL in swine urine, and the R.S.D. was less than 5.0%, the recoveries were in the range of 96.8–103.6% and the linear ranges of CLB and SAL were 0.003–10.0 μg mL−1 and 0.01–20.0 μg mL−1, respectively.

Simultaneous Determination of 23 Prohibited Drugs in Swine Urine by Liquid Chromatography Tandem Mass Spectrometry

A liquid chromatography-electrospray ionization tandem mass spectrometric(LC-ESI-MS/MS) method was developed for the simultaneous determination of 23 forbidden drugs including β-agonists,steriods,nitroimidazoles,sedatives etc.in swine urine.The samples were freeze-dried under vacuum and then dissolved with 10% methanol in water containing 0.1% formic acid,followed by cleanup and enrichment using Anpel MCX solid phase extraction cartridge.Qualitative and quantitative analysis was achieved for the analytes under the multiple reaction monitoring(MRM) mode after the chromatographic separation on a CNW Athena C18(150 mm × 2.1 mm i.d.,5 μm) column.Matrix-matched calibration curves with good correlation coefficients(r0.99) were obtained in the concentration range of 0.5-100 μg/L.The limits of detection(LODs) and the limits of qualification(LOQs) for the 23 compounds were in the range of 0.5-4.0 μg/L(S/N3) and 1.0-10 μg/L(S/N10),respectively.The mean recoveries at the four spiked levels of 1.0-50 μg/L were between 50.2% and 97.9% with the intra-day relative standard deviation(RSD) less than 10% and inter-day RSD less than 18%.The proposed method was successfully used to detect 23 banned drugs in 200 swine urine samples,two of them contained clenbuterol,with the concentrations of 4.45 and 2.16 μg/L,respectively.

Natural Occurrence of Thiouracil in Urine of Livestock in Poland

Abstract Natural occurrence of thiouracil in bovine and swine urine in Poland was investigated. Under the national residue control programme, 537 urine samples were tested. In 77 samples (14.3%) thiouracil was detected above decision limit CCα (0.91 μg L-1), including eight samples over the recommended concentration of 10 μg L-1. Of the bovine urine samples, 95 and 99 percentiles have thiouracil concentration below 4.50 and 14.85 μg L-1 ,and of porcine samples below 2.35 and 6.80 μg L-1, respectively.

Development of a new rabbit monoclonal antibody and its based competitive indirect enzyme‐linked immunosorbent assay for rapid detection of sulfonamides

Monoclonal antibodies generally obtained through the classic mouse hybridoma system were requisite for the establishment of various immunoassays. In this study, a new rabbit monoclonal antibody (RabMAb) against sulfonamides (SAs) was first produced via hybridoma technique in rabbit. The related enzyme-linked immunosorbent assay (ELISA) was then developed and applied to real sample analysis. A sensitive competitive indirect ELISA method based on a novel RabMAb for rapid detection of sulfonamides was first established. The obtained half-maximum inhibition concentration (IC(50)) values for four SAs were all below 10 ng mL(-1) , with 0.68 ng mL(-1) sulfathiazole (STZ), 1.11 ng mL(-1) sulfadiazine (SD), 1.15 ng mL(-1) sulfapyridine (SP) and 5.27 ng mL(-1) sulfamethoxazole (SMX). Desirable recoveries when detecting different spiked swine urine and milk samples were achieved ranging from 92.6% to 104.3% and from 61.1% to 81.6%, respectively. The proposed immunoassay with the newly developed RabMAb is capable of detection of four SAs (STZ, SD, SP and SMX) with proven satisfactory performance and is applicable for routine large-scale analysis in practical uses.

Investigation of the ultrasound effect and target analyte selectivity of dispersive liquid–liquid microextraction and its application to a quinocetone pharmacokinetic study

An ultrasound-assisted dispersive liquid–liquid microextraction (UADLLME) was developed as a simple, sensitive, and robust method for the simultaneous determination of quinocetone (QCT) and three of its synthesized desoxy metabolites in swine urine samples via high-performance liquid chromatography (HPLC). Experimental parameters were optimized using the one-factor-at-a-time approach and were followed using an orthogonal array design. The results indicate that ultrasonic irradiation significantly affects the DLLME extraction efficiency. Moreover, the intermolecular binding energies and octanol–water partition ratio (Kow) of the target analytes were calculated using the density functional theory and the atom-additive method, respectively. A high correlation was found between the extraction efficiency and the calculated results, which may serve as a scientific guideline in the determination of the target analyte selectivity of DLLME. The feasibility of UADLLME with HPLC for the simultaneous determination of QCT and its desoxy metabolites in blank swine urine samples was then investigated. Higher enrichment factors (118–175), low limits of detection (0.06–0.12ngmL−1), and high precisions (relative standard deviation < 2.5%) were obtained. Calibration curves were performed in the 0.5–500ngmL−1 range and displayed good linearity. In addition, the proposed method was successfully applied to the pharmacokinetic study of QCT and its desoxy metabolites in real urine samples. The results show that UADLLME has a potential application in the pharmacokinetic and residue studies of quinoxaline-N-dioxides derivatives in biological fluid samples.

Parâmetros bioquímicos sanguíneos, balanço de nitrogênio e metabolizabilidade da energia bruta em suínos alimentados com dietas contendo diferentes balanços eletrolíticos

The aim of this study was to evaluate different dietary electrolyte balance (DEB) on the blood biochemical parameters, nitrogen balances and crude metabolizable energy of swine in the initial phase. Sixteen barrows were used, averaging 27.95 kg of initial weight, allotted individually in metabolic cages in a randomized blocks design with four treatments (DEB of 160, 208, 257 and 305 mEq/kg) and 4 replicates. The blood biochemical parameters analyzed were chloride, potassium, sodium and urea in blood. Urine pH was also evaluated, and the parameters evaluated in nitrogen (N) balance were N intake, fecal N, N excreted in urine, absorbed N, N retention, retained N/absorbed N and total excretion of N. The gross energy digestibility and metabolizibility coefficients were determined, and the respectives values of digestible and metabolizable energy. The values of urinary pH increased (P &lt; 0.01) linearly with increasing levels of DEB, ranging from 6.90 to 8.03. The results for chloride, potassium and nitrogen balances of variables and gross energy were similar (P &gt; 0.05) between the evaluated DEB. A linear increase (P &lt; 0.01) was also observed for sodium concentrations in blood serum due to the increase of DEB, with values of 2.91, 3.03, 3.27 and 3.18 g/l, respectively for the different treatments. Urea levels in blood serum increased linearly (P &lt; 0.01), with values of 26.21, 28.64, 34.32 and 32.89 mg/dl. It was concluded that increasing the dietary electrolyte balance, from 160 to 305 mEq/kg resulted in higher concentrations of urea and sodium in blood serum, and higher pH values in the urine of swine in the initial phase.

Blood biochemical parameters, nitrogen balance and gross energy metabolizability in pigs fed with different dietary electrolyte balances.

The aim of this study was to evaluate different dietary electrolyte balance (DEB) on the blood biochemical parameters, nitrogen balances and crude metabolizable energy of swine in the initial phase. Sixteen barrows were used, averaging 27.95 kg of initial weight, allotted individually in metabolic cages in a randomized blocks design with four treatments (DEB of 160, 208, 257 and 305 mEq/kg) and 4 replicates. The blood biochemical parameters analyzed were chloride, potassium, sodium and urea in blood. Urine pH was also evaluated, and the parameters evaluated in nitrogen (N) balance were N intake, fecal N, N excreted in urine, absorbed N, N retention, retained N/absorbed N and total excretion of N. The gross energy digestibility and metabolizibility coefficients were determined, and the respectives values of digestible and metabolizable energy. The values of urinary pH increased (P 0.05) between the evaluated DEB. A linear increase (P < 0.01) was also observed for sodium concentrations in blood serum due to the increase of DEB, with values of 2.91, 3.03, 3.27 and 3.18 g/l, respectively for the different treatments. Urea levels in blood serum increased linearly (P < 0.01), with values of 26.21, 28.64, 34.32 and 32.89 mg/dl. It was concluded that increasing the dietary electrolyte balance, from 160 to 305 mEq/kg resulted in higher concentrations of urea and sodium in blood serum, and higher pH values in the urine of swine in the initial phase.

Simultaneous determination of 10 β2-agonists in swine urine using liquid chromatography–tandem mass spectrometry and multi-walled carbon nanotubes as a reversed dispersive solid phase extraction sorbent

A simple and inexpensive pretreatment procedure was developed for 10 β2-agonists (clenbuterol, ractopamine, salbutamol, bambuterol, penbuterol, tulobuterol, clorprenaline, mabuterol, cimaterol and terbutaline) in swine urine using dispersive solid phase extraction (dSPE) with multi-walled carbon nanotubes (MWCNTs). The sample was analysed after purification by ultra high performance liquid chromatography–positive electrospray ionisation tandem mass spectrometry (UHPLC-ESI–MS/MS). The pH value of the swine urine, extraction time, type and amount of MWCNTs and type of eluent were optimised to increase the sample throughput and sensitivity. The samples were quantified using clenbuterol-D9, ractopamine-D6 and salbutamol-D3 as internal standards. The recoveries of the target compounds from swine urine samples at pH 10.0 were most efficient when using 20mg of MWCNTs with a 30–50nm outer diameter and a length of 10–30μm, while a mixture of water/methanol (90:10, v/v) with 0.5% formic acid was shown to be the most suitable solvent for desorbing the compounds from the MWCNTs. The proposed method was validated according to the European Commission Decision 2002/657/EC, which determines linearity, specificity, decision limit (CCα), detection capability (CCβ), recovery, precision and stability.

Ultrasensitive detection of trace amount of clenbuterol residue in swine urine utilizing an electrochemiluminescent immunosensor

Abstract As a familiar β 2 -agonist, clenbuterol (CLB) was frequently reported to be illegally abused as a “lean meat agent” for livestock breeding, since it could improve growth rate and inhibit fat synthesis. Due to its potential hazard to human health, it has been forbidden as growth promoter for food-producing animal feeding in most countries. Therefore, the routine monitoring of CLB abuse is exceedingly necessary for food safety purpose. We herein report an ultrasensitive electrochemiluminescent immunosensor, which is firstly applied for assay of trace amount of CLB residue in swine urine. In this investigation, gold nanoparticles doped chitosan composite film was utilized for antigen immobilization, and Ru(bpy) 3 2+ -labeled antibody was utilized as the tracer antibody. With a competitive immunoassay format, good analytical performance was obtained. The proposed method shows a linear range of 0.010–1.0 ng/mL, with a limit of detection of 0.0050 ng/mL for CLB, which is evidently lower than that of most previous reports. This method is suitable for screening of trace amount of CLB residue, due to its simple manipulation, short assay time, and high detection sensitivity, and exhibits great promise in food safety and agonist monitoring.

Highly sensitive near-simultaneous assay of multiple “lean meat agent” residues in swine urine using a disposable electrochemiluminescent immunosensors array

Nowadays, β2-agonists are abused illegally as “lean meat agents” for food-producing animals, and cause increasing food-safety accidents in some countries. Due to their hazard to the human health, “lean meat agents” are banned in most countries and required to be routinely monitored. We herein report a disposable electrochemiluminescent immunosensors array for near-simultaneous assay of multiple β2-agonist residues in swine urine, by using ractopamine and salbutamol as the models. In this investigation, a screen-printed carbon electrodes array was assembled and acted as the substrate of the immunosensors array. Then the immunosensors array was constructed by site-selectively immobilizing the antigens of ractopamine and salbutamol on the working electrodes of array. After the competitive immuno-binding, with the aid of a homemade single-pore-four-throw switch, the electrochemiluminescent signals of the two β2-agonists were sequentially detected using a non-array detector. The limits of detection for ractopamine and salbutamol were 8.5 and 17pg/mL, respectively, which were much lower than those of the most previous reports. Compared with other routine methods based on chromatography and ELISA, this method is more suitable for screening of multiple β2-agonists in quantities of samples, owing to its merits of low cost, user-friendliness and high throughput, and shows great promise in food safety and agonist surveillance.