A Group-Specific Microbiological Test for the Detection of Tetracycline Residues in Raw Milk

Performance of Tet-Lux, a newly developed microbiological test for the detection of tetracycline residues in raw milk, based on tetracycline-controlled luminescence activation of the test bacteria, was evaluated in bovine milks with variable amounts of somatic cells, bacteria, fat, protein, and natural inhibitory compounds. The sensitivity of Tet-Lux was also compared to a commercially available tetracycline immunoassay (Snap, Idexx Laboratories Inc.) and to a microbial inhibition test (Delvotest SP, Gist-Brogades). There were slight differences in the luminescence signals between different milk samples, but no single factor could be pointed out to be responsible for them. There appeared to be a modest inverse relationship between luminescence and increasing fat and protein content. The amount of somatic cells, bacteria, and the natural inhibitors lysozyme and lactoferrin did not affect the luminescence response. The test fulfilled the sensitivity requirement specified by the European Union (maximum residue limit 100 ng/ml for tetracyclines). The Tet-Lux test was clearly more sensitive to all tetracyclines tested (oxytetracycline, tetracycline, chlortetracycline, doxycycline, demeclocycline, methacycline, minocycline) than Delvotest SP, and for five tetracyclines out of seven more sensitive than Snap. The test provides a fast, simple, and robust microbial method for the qualitative detection of tetracycline residues in milk.

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Stability of Tetracycline Antibiotics in Raw Milk under Laboratory Storage Conditions

Journal of Food Protection ◽

10.4315/0362-028x-62.5.547 ◽

1999 ◽

Vol 62 (5) ◽

pp. 547-548 ◽

Cited By ~ 14

Author(s):

LYNDA V. PODHORNIAK ◽

SHANITA LEAKE ◽

FRANK J. SCHENCK

Keyword(s):

Metal Chelate ◽

Raw Milk ◽

Storage Conditions ◽

Screening Tests ◽

Rapid Screening ◽

Tetracycline Antibiotics ◽

Milk Samples ◽

Bulk Milk ◽

Tetracycline Residues ◽

Metal Chelate Affinity Chromatography

Raw milk samples collected from bulk milk tankers may be screened for the presence of tetracycline antibiotics using rapid screening tests. If tetracycline residues are detected, the milk may be shipped to a laboratory for high-pressure liquid chromatography (HPLC) analysis. Because the milk may be shipped on ice blocks, it is important to know whether tetracycline residues are stable at that temperature and for how long. Control raw milk samples fortified with 50 ppb each chlortetracycline, demeclocycline, methacycline hydrochloride, minocycline, oxytetracycline, and tetracycline were incubated at 4°C or 25°C, then analyzed using a metal chelate affinity chromatography extraction and HPLC. No loss of tetracycline was observed after 48 h of storage at 4°C or 24 h at 25°C. Losses ranging from 4 to 13% and 0 to 18% were noted after 72 h at 4°C and 48 h at 25°C, respectively.

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HPLC-DAD multi-residue method for determination of florfenicol, penicillin and tetracycline residues in raw cow milk

Journal of Clinical and Laboratory Research ◽

10.31579/2768-0487/017 ◽

2021 ◽

Vol 2 (3) ◽

pp. 01-08

Author(s):

Ali Jaber ◽

Zeinab Zahreddine ◽

Simon Abou Haidar ◽

Chadi Hosri ◽

Ghassan Ibrahim ◽

...

Keyword(s):

High Performance ◽

Solid Phase ◽

Raw Milk ◽

Reversed Phase ◽

Cow Milk ◽

Antibiotic Residues ◽

Milk Samples ◽

Antibiotics Residues ◽

Tetracycline Residues

The existence of antibiotic residues in edible products constitutes a health problem to the consumers. Reversed-phase high-performance liquid chromatography with diode array detection (HPLC–DAD) was optimized and validated for the simultaneous determination of florfenicol (FF), penicillin (PE), and tetracycline (TC) residues in dairy raw milk samples. The determination of these antibiotics was carried out on HP-ODS Hypersil C18 (5μm, 125*4 mm) column at a flow rate (1mL/min) and temperature (35 ⁰C). The extraction method includes deproteinization of the milk sample followed by a solid-phase extraction (SPE) clean-up. The method was validated according to the European Commission Decision 2002/657/EC and the International Conference of Harmonization Guidelines. The recoveries for the studied antibiotics ranged from 82–111.54 % making the method suitable for performing routine analysis. The proposed method was applied for the analysis of antibiotic residues in 50 dairy raw milk samples collected from many regions in Lebanon. The results showed the occurrence of these antibiotics residues in milk collected from different Lebanese regions. The numbers indicate that 22 % of milk samples were found to be positive for FF, 42 % for PE, and 28 % for TC residues.

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Testing of Raw Milk for Tetracycline Residues

Journal of Dairy Science ◽

10.3168/jds.s0022-0302(98)70124-9 ◽

1998 ◽

Vol 81 (9) ◽

pp. 2341-2345 ◽

Cited By ~ 16

Author(s):

Jacques F.M. Nouws ◽

Gerard Loeffen ◽

Jan Schouten ◽

Harry Van Egmond ◽

Henk Keukens ◽

...

Keyword(s):

Raw Milk ◽

Tetracycline Residues

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Simultaneous Determination of Multiple Tetracycline Residues in Milk by Metal Chelate Affinity Chromatography: Collaborative Study

Journal of AOAC International ◽

10.1093/jaoac/79.1.29 ◽

1996 ◽

Vol 79 (1) ◽

pp. 29-42 ◽

Cited By ~ 5

Author(s):

Mary C Carson ◽

Wayne Breslyn ◽

J Carmany ◽

S Cross ◽

W H Farrington ◽

...

Keyword(s):

Metal Chelate ◽

Collaborative Study ◽

Raw Milk ◽

Milk Samples ◽

Relative Standard ◽

Control Milk ◽

Fast Flow ◽

Tetracycline Residues ◽

Liquid Chromatographic

Abstract To meet federal and state regulatory needs, a liquid chromatographic (LC) method with ultraviolet (UV) detection was developed for determination of 7 tetracyclines at 30 ng/mL in milk. Raw milk samples are defatted, acidified, and centrifuged to remove proteins, and tetracyclines are specifically absorbed from the milk by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns. Tetracyclines are removed from these columns with EDTA-containing buffer, and extracts are further cleaned by ultrafiltration. Finally, extracts are concentrated and analyzed simultane ously by using on-line concentration. This method was validated in a collaborative study that involved 11 laboratories, including the authors’ laboratory. Each laboratory was asked to prepare and analyze known control and fortified milk samples, as well as 18 coded blind samples. Eight laboratories completed all analyses. Average interlaboratory recoveries for the known fortified samples ranged from 59% (methacycline at 15 ng/mL) to 78% (oxytetracy cline at 60 ng/mL). Average recovery for each of 7 residues at 30 ng/mL were between 60 and 110%, meeting single-residue guidelines for accuracy set by the U.S. Food and Drug Administration. Reproducibility relative standard deviation (RSDR) for the known fortified samples varied from 11 to 39%, with 6 of 7 residues at the 30 ng/mL level having RSDR values at or below 20%. Seven of 8 laboratories correctly identified blind control milk samples and all 28 residues present in blind samples. The metal chelate affinity—LC method for determination of multiple tetracycline residues in milk has been adopted first action by AOAC INTERNATIONAL.

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Evaluation of a Modified Enzymatic Test for the Detection of Tetracyclines in Milk

Journal of Food Protection ◽

10.4315/0362-028x-62.6.632 ◽

1999 ◽

Vol 62 (6) ◽

pp. 632-636 ◽

Cited By ~ 2

Author(s):

EVA D'HAESE ◽

HANS J. NELIS ◽

WIM REYBROECK ◽

HENDRIK DE RUYCK

Keyword(s):

Raw Milk ◽

Maximum Residue Limit ◽

Test Protocol ◽

False Negatives ◽

Somatic Cell Counts ◽

Milk Samples ◽

Cell Counts ◽

Tetracycline Residues ◽

Enzymatic Test ◽

Good Agreement

The tetracycline galactosidase (TG) test, a new method for the detection of tetracycline residues in raw milk based on the inhibition of β-galactosidase biosynthesis in Escherichia coli, was previously validated with spiked milk samples. It has now been applied to milk from cows treated with oxytetracycline. In view of the occurrence of false positives, related to highly elevated somatic cell counts (>106/ml), the improved TG test was developed, in which a heating step (80°C, 15 min) preceded the original TG test protocol. A good agreement with other assays (Delvotest SP, the Bacillus cereus microtiter test, the LacTek tetracycline milk screening test, the Charm HVS-8100 tetracycline test) as well as with high-pressure liquid chromatography was obtained. No false negatives were observed with reference to the established maximum residue limit for tetracyclines of 100 μg/kg milk.

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Simultaneous Determination of Multiple Tetracycline Residues in Milk Using Metal Chelate Affinity Chromatography

Journal of AOAC International ◽

10.1093/jaoac/76.2.329 ◽

1993 ◽

Vol 76 (2) ◽

pp. 329-334 ◽

Cited By ~ 18

Author(s):

Mary C Carson

Keyword(s):

Metal Chelate ◽

Raw Milk ◽

Good Precision ◽

Milk Samples ◽

Fortified Milk ◽

On Line ◽

Fast Flow ◽

Tetracycline Residues ◽

Metal Chelate Affinity Chromatography

Abstract A method was developed for the determination of 7 tetracyclines in milk. Raw milk samples are defatted, acidified, and centrifuged to remove proteins, and the tetracyclines are specifically absorbed from the milk by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns. The tetracyclines are removed from these columns with EDTA-containing buffer, and the extracts are further cleaned up by centrifugal ultrafiltration. Finally, the extracts are concentrated and analyzed simultaneously by on-line concentration. This method has limits of detection for individual tetracyclines of <5 ng/mL and was validated with fortified milk samples at 15,30, and 60 ng/mL. Recoveries exceeded 60% for all tetracyclines at all levels, with good precision. The method was also tested on milk from cows dosed with each of the tetracyclines. Advantages of this method over existing methods include its sensitivity, minimal use of organic solvents, and speed; with an autosampler, at least 14 samples can be processed and analyzed in 1 day.

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