Testing of Raw Milk for Tetracycline Residues (original) (raw)
Related papers
A Group-Specific Microbiological Test for the Detection of Tetracycline Residues in Raw Milk
Journal of Agricultural and Food Chemistry, 2000
The potentiality of using a luminescent Escherichia coli strain for the specific detection of tetracycline residues in raw bovine milk was investigated. The sensor cells contain a reporter plasmid carrying the bacterial luciferase operon of Photorhabdus luminescens under the control of the tetracycline responsive control region from transposon Tn10. Incubation of the cells with the sample containing tetracyclines increases the light emission of the sensor cells. The most sensitive tetracycline detection was achieved in 120 min and by using CDTA as a chelating agent in the assay. Heat-treatment of milk before the assay decreased the variations in background luminescence signals and in tetracycline-induced luminescence between different milk samples. The detection limits for tetracycline, oxytetracycline, chlortetracycline, doxycycline, methacycline, demeclocycline, and minocycline were between 2 and 35 ng/mL. Nontetracycline antibiotics did not significantly interfere with the detection of tetracyclines.
Asian Journal of Dairy and Food Research, Volume 43 Issue 2: 306-312 (June), 2024
Background: This study aimed to identify tetracycline residues in milk consumed in the region of Constantine (northeast Algeria) using ELISA based tetracyclin kit. Methods: A total of 180 samples were analyzed (fresh cow milk and imported powdered milk). To compare ELISA and HPLC detection values, 22 fresh milk ELISA positive samples were confirmed by HPLC analysis. Result: 92.5% of fresh milk samples contained tetracycline residues at values between 5 and 74 µg/L and 33.3% of the samples showed concentrations between 49 and 74 µg/L, that exceed the MRLs recommended by the FDA. No significant differences (p>0.01) were found between the values obtained by the two methods.
Highly Sensitive Immunochromatographic Identification of Tetracycline Antibiotics in Milk
International Journal of Analytical Chemistry, 2015
A rapid immunochromatographic assay was developed for the control of tetracycline (TC). The assay is based on the competition between immobilized TC-protein conjugate and TC in a tested sample for binding with polyclonal anti-TC antibodies conjugated to colloidal gold during the flow of the sample along a membrane strip with immobilized reactants. Conjugation of colloidal gold and the total immunoglobulin (IgG) fraction of polyclonal antibodies was used to increase the assay sensitivity to ensure low content of specific antibodies in the conjugate. This allowed effective inhibition of free TC and conjugate binding in the strip test zone. Photometric marker registration allows control of the reduction of binding, thereby enhancing detection sensitivity. The proposed assay allows TC to be detected at concentrations up to 20 ng/mL, exceeding the limit of detection of the known analogues, in a wide working range (more than two orders) of 60 pg/mL to 10 ng/mL, ensured through the use of polyclonal antibodies. The assay time is 10 min. The efficiency of the designed assay is shown to identify TC in milk; the degree of recovery of TC ranges from 90 to 112%. The precision of the concentrations measurements was no more than 10%.
Daily ingestion of tetracycline residue present in pasteurized milk: a public health problem
Environmental Science and Pollution Research, 2014
The objective of this study was to evaluate (qualitatively and quantitatively) the occurrence of antibiotic residue in pasteurized milk in Brazil. Pasteurized milk samples (n = 252) were collected monthly from Nov. 2010-Oct. 2011 from 21 commercial establishments (brands). A screening test (Delvotest® SP-NT) was applied to those samples. In positive (n =19) and/or suspect samples (n =24), we quantified oxytetracycline (OTC) and tetracycline (TC) by highperformance liquid chromatography with diode array detector (HPLC-DAD). OTCs were detected in all positive samples and TCs in six. In the 24suspected samples, OTCs were detected in 23 and TCs were not found in 8. Of the milk brands evaluated (n =21), the presence of antibiotic residue was not detected in 4; in the other brands, both positive and suspect samples were verified. Results indicate the presence of antibiotic residue above legal limits. According to actual milk consumption in Brazil (441 mL/kg BW/day), in only 9 of the 17 brands of milk with antibiotic residue, the estimated daily intake was at or less than the maximum recommended by the European Union. The screening test used was effective to identify the presence of antibiotic residue (OTC and TC), confirmed by HPLC-DAD. The OTC is the predominant antimicrobial used by dairy farmers. Ingestion of contaminated milk by OTC and TC can increase the resistance of microorganisms to antibiotics.
Iranian Journal of Veterinary Medicine, 2014
BACKGROUND: Tetracyclines (TCs) are broad-spectrumantibiotics that are widely used in veterinary medicine. Thepresence of TCs residues in milk is a public health concern allover the world. OBJECTIVES:This study aimed to determine TCsresiduals in pasteurized milk marketed by some dairy companiesin Tehran from April 2011 to March 2012. METHODS: 432pasteurized milk samples were purchased from supermarketssupplying the milk products of 12 major dairy companies inTehran (3 samples from each company every month), and theywere stored at -20 0C until analysis. Oxytetracycline (OTC) andTetracycline (TC) residues in each sample were extracted by aliquid - liquid phase procedure and quantitated using a highperformance liquid chromatographic (HPLC) method. Chromatographicconditions included a mobile phase as oxalic acidbuffer- acetonitril (80: 20) with a flow rate of 1mL/min and UVdetectionat 355 nm. RESULTS: TCs residuals in most milksamples were lower than 100 ppb, maximum residue level(MRL);...
Journal of AOAC INTERNATIONAL, 1999
A multiresidue method for isolation and liquid chromatographic determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) in milk is presented. The sensitivity of the method is adequate to meet the needs of regulatory agencies. The European Community established 100 μg/kg as the maximum residue limit (MRL) in milk for TC, CTC, and OTC. Recoveries exceeded 80% for all tetracyclines at all levels, with good precision. Correlation coefficients of standards curves for individual tetracyclines isolated from fortified samples ranged from 0.991 for CTC to 0.998 for OTC. Other antibiotics that might interfere with analysis did notinterfere with elution times of OTC, TC, andCTC. The procedure is rapid, precise, and quantitative and requires minimal preparation andminimal use of organic solvents. It can beapplied to routine surveillance programs. We canprepare 10 samples for analysis in about 1.45 h.
In Vivo
Background/Aim: The presence of tetracycline (TC) and its residues in raw milk and milk dairy products poses a threat to human health due to the induction of antibiotic resistance of bacteria that can be transmitted between animals, humans, and the environment. The aim of this study was to investigate the transfer of TC from raw milk to different dairy products: pasteurized milk, boiled milk, sour milk, skimmed milk, and cottage cheese. We analyzed samples of milk from different sources: household farmers, local farms, and milk factories. Materials and Methods: The analyses of TC in milk and dairy products were performed using colloidal gold immunochromatography assay (GICA) and enzymelinked immunosorbent assay (ELISA). Results: The highest content of TC was found in the milk purchased from local household farmers; therefore, these samples were chosen for the study of TC transfer to dairy products. TC was also found in sour milk at levels comparable with those obtained in raw milk. The average TC content decreased following heat treatment of the milk, as follows: for pasteurized milk 22.07% and for boiled milk 29.35%. The highest concentrations were determined in cottage cheese in the range 200-620 μg/kg. Conclusion: TC residues are transferred from milk to dairy products in various amounts depending on the preparation conditions, and due to their chemical properties, they accumulate in concentrated derivatives, such as cheese. Therefore, TC can be identified even in cheeses prepared from milk with undetected antibiotic levels.
In-house validation for multi-residue analysis of tetracycline in cow milk by HPLC with UV detection
Semina: Ciências Agrárias, 2017
The indiscriminate use of antibiotics in dairy cattle without complying with the waiting period results in residual contamination, whose effective control in produced milk requires validated methods toensure analytical results. The aim of this study was to optimize and validate the HPLC-UV/VIS method at 365 nm for analyzingthe tetracycline in pasteurized cow milk in accordance with the European Community (2002/657/EC). Spiked milk with analytes (oxytetracycline, tetracycline, doxycycline, and chlortetracycline) was submitted to deproteinization and cleaning by a C18 solid-phase column and analyzed by HPLC using a gradient system with 0.01 mol L?1 oxalic acid-acetonitrile-triethylamine (90:9.9:0.1) and acetonitrile on a reverse phase (C18) column. Accuracy and precision were assessed by adding analytes to levels of 0.5, 1, and 1.5 times the permissible maximum limit allowed in Brazil. The method presented selectivity with a decision limit (CC?) and detection capability (CC?) ranging ...
Trace analysis of oxytetracycline and tetracycline in milk by high-performance liquid chromatography
Journal of Agricultural and Food Chemistry, 1990
A high-performance liquid chromatographic (HPLC) method for the determination of oxytetracycline (OTC) and tetracycline (TC) residues in milk a t levels as low as 10 ppb has been developed. Milk was acidified a t pH 2.7 and extracted with acetonitrile. The extract was partly purified by treatment with ammonium sulfate solution and concentrated into a phosphate buffer, pH 8.2. Following addition of tetrabutylammonium reagent (TBA), tetracyclines were extracted as ion pairs with TBA into dichloromethane, reextracted into acid, and analyzed on a reversed-phase CIS, 5 pm, column. Overall recovery was found to be 72.7 f 1.2% for OTC and 85.1 f 1.3% for TC. The linearity was excellent for both compounds in the range examined (r = 0.9996, 23.7-190 ppb of OTC in milk; r = 0.09995, 26.5-212 ppb of TC in milk). Precision data based on within-day and among-days variation suggested an overall relative standard deviation of 5% for OTC and 4.2% for TC.