首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 199 毫秒
1.
Ractopamine hydrochloride is a beta-adrenergic leanness-enhancing agent approved for use in swine in the United States. Depletion of ractopamine and its metabolites from animal tissues, urine, and serum is of interest for the detection of illegal use. The objectives of this study were to measure the residues of ractopamine in swine incurred samples after treatment with dietary ractopamine for 28 consecutive days. An efficient and sensitive analytical method was developed for the detection of parent ractopamine and its metabolites in swine tissues, urine, and serum by HPLC-FLD. After extraction, enzymatic digestion, and solid-phase cleanup of the samples, ractopamine residues were determined by liquid chromatography (LC) with fluorescence detector. The limits of detection (LOD) for tissues, urine, and serum were 1 ng g(-1), 0.5 ng mL(-1), and 0.5 ng mL(-1), respectively. Recoveries ranged from 70.5 to 94.5% for samples fortified at 1-50 ng g(-1) or ng mL(-1). Sixty pigs were fed twice daily for 28 consecutive days with feeds containing 18 mg kg(-1) ractopamine HCl. The residue concentrations in urine, liver, and kidney were 650.06 ng mL(-1), 46.09 ng g(-1), and 169.27 ng g(-1), respectively, compared with those in muscle, fat, and serum (4.94 ng g(-1), 3.28 ng g(-1), and 7.48 ng mL(-1), respectively) at the feeding period of 7 days. The residue concentrations at withdrawal period of 0 days in all edible tissues were lower than tolerance values established by the FDA and MRL values listed by the JECFA. These data support the withdrawal time of 0 days established by the FDA for ractopamine used as feed additive in swine.  相似文献   

2.
Neonicotinoids are systemic insecticides widely used on many pollinated agricultural crops, and increasing evidence indicates that they move to some extent into pollen and nectar. This study measured levels of neonicotinoid residues in pollen and nectar from a pumpkin crop treated with formulated products containing imidacloprid, dinotefuran, and thiamethoxam using different timings and application methods. Environmental conditions have a significant effect on overall residue levels; nectar residues were 73.5-88.8% less than pollen residues, and metabolites accounted for 15.5-27.2% of the total residue amounts. Foliar-applied treatments and chemigated insecticides applied through drip irrigation during flowering resulted in the highest residues of parent insecticide and metabolites, which may reach average levels up to 122 ng/g in pollen and 17.6 ng/g in nectar. The lowest levels of residues were detected in treatment regimens involving applications of insecticides at planting, as either seed dressing, bedding tray drench, or transplant water treatment.  相似文献   

3.
Maduramicin is one of the most widely used coccidiostats in the world. A rapid and accurate analytical method for this drug should provide producers and users with an effective management tool. The current chromatographic methods are sensitive but labor-intensive. This paper reports the development of an enzyme-linked immunosorbent assay (ELISA) based on an immunoaffinity chromatography cleanup procedure for the analysis of maduramicin in broiler chicken tissues (including muscle, liver, and fat). Recoveries from fortified tissue homogenates at levels of 30.0-120.0 microg kg(-)(1) ranged from 76.4 to 107.5% with coefficients of variation of 3.8-16.4%. The limits of detection were 1.0 ng g(-)(1) in muscle, 2.8 ng g(-)(1) in liver, and 1.5 ng g(-)(1) in fat. The ELISA results from the analysis of incurred residue in tissue samples showed the cleanup procedure is viable.  相似文献   

4.
The development of an assay for the detection of streptomycin residues in pasteurized whole milk using an optical biosensor (Biacore) is reported. Streptomycin-adipic hydrazide coupled to bovine thyroglobulin was used to produce a sheep polyclonal antibody. The antibody displayed excellent cross-reactivity with dihydrostreptomycin (106%). There was no significant cross-reaction with other aminoglycosides or common antibiotics. Streptomycin was also immobilized onto a CM5 sensor chip to provide a stable, reusable surface. The developed assay permitted the direct analysis of whole milk samples ( approximately 3.5% fat) without prior centrifugation and defatting. Results were available in 5 min. The limit of detection of the assay was determined as 4.1 ng/mL, well below the European maximum residue limit (MRL) of 200 ng/mL. Repeatability (or coefficient of variation) between runs was determined as 3.5% (100 ng/mL; 0.5 x MRL), 5.7% (200 ng/mL; MRL), and 7.6% (400 ng/mL; 2 x MRL).  相似文献   

5.
This paper reports the development of an immunoassay for the specific analysis of doxycycline (DC), a congener of the tetracycline antibiotic family (TCs), in milk samples. This is the first time that DC antibody production is reported, based on a rationally designed and well-characterized immunizing hapten. The chemical structure of the immunizing hapten (13-[(2-carboxyethyl)thiol]-5-hydroxy-6-α-deoxytetracycline, TC1) was designed to maximize recognition of the tetracycline characteristic moiety defined as lower periphery of the TCs plus the region of the upper periphery composed by the hydroxyl group at position C(5) (B ring) and the dimethylamino group in ring A. Polyclonal antibodies raised against TC1 coupled to horseshoe crab hemocianyn (HCH) were used to develop a homologous indirect competitive enzyme-linked immunosorbent assay (ELISA). The microplate ELISA can detect DC in buffer down to 0.1 μg L(-1). The ELISA has been proven to tolerate a wide range of ionic strengths and pH values. The assay is very selective for DC with a minor recognition of methacycline (32% of cross-reactivity). Experiments performed with whole milk samples demonstrate that samples can be directly analyzed after a simple treatment method, reaching detectability values below 5 μg L(-1).  相似文献   

6.
Improper application of antibiotic chemicals to livestock and aquaculture species may lead to the occurrence of residues in food supplies. An appropriate depletion period is needed after the administration of drugs to animals for ensuring that residues in edible tissues are below established tolerance levels. This study was conducted to determine incurred amoxicillin residues in catfish muscle following oral administration. Dosed fish were harvested after four depletion periods, and muscle fillets were analyzed for amoxicillin residues using an HPLC method with precolumn derivatization and fluorescence detection. The residue levels in fish after a 6-h depletion ranged from 40 to 64 ng/g with one exception at 297 ng/g. Average residue levels decreased to 5.4 and 2. 8 ng/g after 24- and 48-h depletions, respectively. Residue levels after a 72-h depletion decreased to below the method's limit of quantitation (1.2 ng/g). An LC-MS/MS confirmatory method was developed. Confirmation of the presence of amoxicillin was demonstrated in incurred fish samples containing residues at approximately 50-300 ng/g.  相似文献   

7.
4-epioxytetracycline and N-demethyloxytetracycline, as metabolites of oxytetracycline (OTC), 4-epitetracycline and N-demethyltetracycline, as metabolites of tetracycline (TC), and 4-epichlortetracycline, isochlortetracycline (ICTC), 4-epi-ICTC, and N-demethyl-ICTC, as metabolites of chlortetracycline (CTC), were detected in egg yolk and plasma obtained from feeding studies with either OTC, TC, or CTC. In egg white, only OTC, TC with its 4-epimer, and ICTC with its 4-epimer were detected in substantial concentrations. The ratios of epimerization and N-demethylation in the eggs did not change during the medication period. The samples were analyzed by an automated HPLC system (ASTED) with UV, fluorescence, or MS-MS detection.  相似文献   

8.
A new method for the detection and quantification of ethephon residues in fruit and vegetables was developed. The present study indicates that fruit and vegetables require a rapid and simple cleanup step before using gas chromatograph/mass spectrometry. The recovery and precision of the new method were evaluated by spiking the fruit and vegetable samples with 0.01-0.1 microg/g of ethephon. The amount of ethephon residue can be determined with good accuracy (recovery, 78.6-109%; coefficient variation, 2.65-6.41%), and the detection limit, defined as the amount of ethephon equivalent to three standard deviations (SD) of the noise level in observations at the baseline level of the selected ion (m/z 110), was 4 pg. The determination limit, defined as the equivalent to 8 SD of the noise level, was 11 pg. The working range was between 10 and 1000 ng/mL, and the correlation coefficient was 0.999 in the five experiments. Ethephon residues were determined between <2 and 97 ng/g in commercial pineapples from Western Japan.  相似文献   

9.
A biosensor method, using the surface plasmon resonance (SPR) principle, was developed for the determination of ractopamine in cattle and sheep urine. A monoclonal antibody was used to compete with ractopamine in the sample and ractopamine immobilized on the sensor chip. Addition of bovine serum albumin (BSA, 1 mg/mL) as an antibody stabilizer to the incubation buffer was required to achieve a stable biosensor response throughout each sample set. The calibration curve gave a mean IC(50) of 4.7 +/- 0.21 ng/mL (n = 7). Over sample concentrations from 2.5 to 10 ng/mL recoveries were typically approximately 100-110%, whereas inter- and intra-assay reproducibilities (% CV) were usually less than 10 and 6%, respectively. Comparison of biosensor results with results obtained from high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assays (ELISA) using enzyme-hydrolyzed urine (to convert ractopamine conjugates to free ractopamine) gave correlation coefficients of 0.94 for sheep and 0.86 for cattle. Slopes of the lines, with zero intercepts, equaled 0.80 for sheep and 0.74 for cattle. For untreated (nonhydrolyzed) urine samples, the correlations between biosensor and HPLC results were 0.95 for sheep and 0.72 for cattle with slopes of 1.18 (sheep) and 1.69 (cattle). The slopes greater than unity indicate that the biosensor responded to ractopamine metabolites in addition to free ractopamine. The biosensor assay is an excellent analytical tool to screen ractopamine residues in sheep or cattle urine, and the results should be extendible to other species with suitable validation.  相似文献   

10.
A high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed for the detection of cefquinome (CEQ) residues in swine tissues. The limit of detection (LOD) of the method was 5 ng g(-1) for muscle and 10 ng g(-1) for fat, liver, and kidney. Mean recoveries of CEQ in all fortified samples at a concentration range of 20-500 ng g(-1) were 80.5-86.0% with coefficient of variation (CV) below 10.3%. Residue depletion study of CEQ in swine was conducted after five intramuscular injections at a dose of 2 mg kg(-1) of body weight with 24 h intervals. CEQ residue concentrations were detected in muscle, fat, liver, and kidney using the HPLC-UV method at 265 nm. The highest CEQ concentration was measured in kidney tissue during the study period, indicating that kidney was the target tissue for CEQ. CEQ concentrations in all examined tissues were below the accepted maximum residue limit (MRL) recommended by the Committee for Veterinary Medical Products of European Medical Evaluation Agency (EMEA) at 3 days post-treatment.  相似文献   

11.
Methods to refine the assessment of exposure of wild birds and mammals to pesticides required measurement of pesticide residues in very small samples of their diets. Sample sizes were in the 1-100 mg range, and the target residue for measurement was 0.01 mg/kg. Gas chromatography-mass spectrometry (GC-MS) with large volume injection was compared with the use of an accelerator mass spectrometer (AMS) to measure residues of pesticide labeled at near-background levels with carbon-14. The GC-MS method was able to detect residues down to 0.1 ng per item of diet, and the AMS detected the radiolabel down to 1 mBq (0.06 disintegration per minute, 1 ng of pesticide at the specific activity used) per sample. The target residue level was achieved by the GC-MS method for samples down to 10 mg. The GC method appeared to be best suited to monitoring residues in field studies, and the AMS shows great potential for use in laboratory experiments concerning pesticide degradation.  相似文献   

12.
The determination of damaged starch and diastatic activity in flour was studied using a flow-injection analysis (FIA) biosensor system. The system consisted of an oxygen electrode and an immobilized enzyme column containing purified glucoamylase and glucose oxidase immobilized on activated aminopropyl glass beads. The biosensor system has an optimum pH between 6.5 and 7.5 and an optimum temperature of 35°C for glucose measurement. The response of the FIA biosensor was linear up to 1.000 g/L of glucose with a lower detection limit of 0.025 g/L. Each assay took about 20 min, and the system showed good reproducibility (r = 0.998, n = 8). When applied to the measurement of damaged starch and diastatic activity in wheat flour, the results obtained agreed with those obtained using the conventional methods of measurement. This biosensor system is a rapid practical alternative for the measurement of damaged starch and diastatic activity in wheat flour.  相似文献   

13.
A rapid confirmatory method for monitoring chloramphenicol (CAP) residues in honey, whole milk, and eggs is presented. This method is based on the polymer monolith microextraction (PMME) technique and high-performance liquid chromatography (HPLC)-electrospray ionization mass spectrometry (MS). A poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column was selected as the extraction medium. To obtain optimum extraction efficiency, several parameters related to PMME were investigated. After dissolution in 20 mM phosphate solution at pH 4.0 and centrifugation, honey, eggs, or milk samples were directly passed through the extraction tube. The LC-MS instrument was equipped with an electrospray ion source and a single quadrupole. The eluates were analyzed by LC-MS in the negative-ion mode and by monitoring a pair of isotopic ions for the target compound. The in-source collision-induced dissociation process produced confirmatory ions. The recoveries of CAP from real samples spiked at 0.1-10 ng/g (honey), 0.2-10 ng/mL (milk), and 0.2-10 ng/g (egg) were in the range of 85-102%, with relative standard deviations ranging between 2.1% and 8.9%. The limits of detection (S/N = 3) were 0.02 ng/g, 0.04 ng/mL, and 0.04 ng/g in honey, milk, and eggs, respectively. The proposed method was proved to be robust in monitoring CAP residue in honey, milk, and eggs.  相似文献   

14.
A HPLC method using a modified sample preparation procedure was optimized and validated for the quantification of 10 quinolones (QNs), including marbofloxacin, ciprofloxacin, norfloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, and flumequine, in swine, chicken, and shrimp tissues. In this method, only a small mass (相似文献   

15.
An automated immunoassay for the detection of nicarbazin residues in poultry eggs and liver was developed. The assay was based on a novel all-in-one dry chemistry concept and time-resolved fluorometry. The analyte specific antibody was immobilized into a single microtiter well and covered with an insulation layer, on top of which the label was dried in a small volume. The extracted sample was added automatically to the dry microtiter well, and the result was available within 18 min. Due to the rapidity and simplicity, the quantitative immunoassay could also be used as a high throughput screening method. The analytical limit of detection for the assay was calculated as 0.1 ng mL(-)(1) (n = 12) and the functional limit of detection as 3.2 ng g(-)(1) for egg (n = 6) and 11.3 ng g(-)(1) for liver (n = 6) samples. The sample recovery varied from 97.3 to 115.6%. Typically, the intra-assay variations were less than 10%, and interassay variations ranged between 8.1 and 13.6%.  相似文献   

16.
Tetracycline(TC)and tetracycline resistance genes(TRGs)in plant edible tissues pose a potential risk to the environment and then to human health.This study used a pot experiment to investigate the effects of different remediation substances(worm castings,fungal chaff,microbial inoculum,and biochar)on the physiological characteristics of maize and the residues of TC and TRGs in the soil-maize system under TC stress.The results showed that TC significantly inhibited growth,disrupted the antioxidant defense system balance,and increased proline and malondialdehyde contents of maize plants.Tetracycline residue contents were significantly higher in root than in shoot,and followed the order root>stem-leaf>grain,which was consistent with the distribution of bioconcentration factors in the different organs of maize plants.The TC residue content in the soil under different treatments was 0.013–1.341 mg kg-1.The relative abundances of different antibiotic resistance genes in the soil-maize system varied greatly,and in maize plants followed the order intI1>tetW>tetG>tet B>tetM>tetX>tetO.In the soil,tetX had the highest relative abundance,followed by tetG and tetW.A redundancy analysis(RDA)showed that TC was positively correlated with TRGs.The addition of different remediation substances alleviated the toxicity of TC on maize physiological characteristics and reduced the TC and TRG residues in the soil-maize system,with biochar being the best remediation substance.These results provide new insights into the effect of biochar on the migration of TC and TRGs from soil to plants.  相似文献   

17.
Competitive exclusion of intestinal pathogens by administration of beneficial and defined cultures of normal intestinal microflora is a safe and effective means of reducing the incidence and severity of chick infections with Salmonella and other intestinal pathogens. It is important that competitive exclusion cultures not carry genetic material (e.g., plasmids), which could transfer antibiotic resistance to other microflora, including pathogens. As such, safe and effective competitive exclusion cultures must be sensitive to commonly used antimicrobial agents. By necessity, intentional or accidental exposure of these beneficial microflora to antibiotics will reduce or eliminate the protection provided by competitive exclusion culture establishment. As antibiotic residues can be present from embryonic, hatchling, or maternal administration, a rapid and sensitive assay for the nonspecific detection of residues, which could interfere with competitive exclusion culture establishment, is needed. This study was conducted to develop a rapid and inexpensive bioassay to detect multiple antimicrobial residues in egg yolk and neonatal yolk sacs. Aerobic bacterial strains with known sensitivity to several antibiotics used by the poultry industry were selected and individually compared for sensitivity to enrofloxacin, gentamicin, tetracycline, ceftiofur, and tylosin concentrations in egg yolks. This assay was found to be relatively sensitive for the detection of these antimicrobials, and detection of residues was associated with reduced competitive exclusion culture (PREEMPT) establishment in one experiment. Importantly, this assay can be implemented with minimal training or equipment under commercial hatchery practices and could be used to determine embryo groups, in advance of hatch, that are not suitable candidates for competitive exclusion treatment in the hatchery.  相似文献   

18.
Regarding anti-infectious agents, no maximum residue limits are fixed for honey in the European legislation. Discussions are being conducted in order to set working limits at the European level; for example, for tetracyclines, 20 microg/kg was proposed. The Tetrasensor Honey test kit is a receptor-based assay using dipsticks for a rapid screening (30 min) of honey on the presence of tetracyclines. The test was validated according to Commission Decision 2002/657/EC. The test detects tetracycline, oxytetracycline, chlortetracycline, and doxycycline in honey in a specific and sensitive way. Depending on the type of tetracycline, detection capabilities (CCbeta) between 6 and 12 microg/kg were obtained (4-7 microg/kg for dried dipsticks). The test is rugged and participation with the test in an international ring trial gave compliant results. It can be concluded that the Tetrasensor Honey test kit is a simple and reliable test that can even be used at the production site.  相似文献   

19.
A radioimmunological assay (RIA) to detect chloramphenicol (CAP) residues in eggs, milk, and meat is described. For tissues and other edible products of chloramphenicol-treated animals (chickens, cows, and pigs), the limit of detection is about 200 ng/kg. Residue levels above 1 microgram/kg can easily be quantitated. When highly specific antisera produced in sheep were used, cross-reactivity was insignificant except for metabolites deviating from the parent compound in the acyl side chain only. Thiamphenicol fails to bind to the antisera; hence, it does not interfere with the assay. In the procedure described, the role of cleanup is merely to remove lipids. Thus, skim milk can be analyzed following appropriate dilution without cleanup. The results obtained by RIA were confirmed by gas chromatography with electron capture detection. The new RIA allows rapid, sensitive, and specific screening of large numbers of samples.  相似文献   

20.
氟乐灵在土壤中的持留及其结合残留研究   总被引：3，自引：0，他引：3       下载免费PDF全文
安琼  陈祖义 《土壤学报》1993,30(3):304-311
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号