Time-Resolved Luminescence Screening of Antibiotics in Tissue Matrices without Centrifugation and Filtration:  Spiked Recovery Studies

Abstract

Analyses of chemical residues in animal tissue matrices require multistep sample preparation. To simplify this process, a methodology was developed that combines sorbent extraction and solid-matrix time-resolved luminescence (TRL); it was applied to tetracycline screening in milk. Reported here is an effort to extend its application to tissue matrices, illustrated by oxytetracycline (OTC) screening in catfish muscle. Extraction and enrichment are accomplished by immersing small C18 sorbent strips into tissue homogenates for 20 min, followed by a 3 min rinse in water and a 2 min dip in a reagent solution. After desiccation, TRL is measured directly on the sorbent surface. Tissue particulates no longer interfere via attenuation or scattering, rendering centrifugation and filtration unnecessary. The integrated TRL intensity shows a linear dependence on OTC concentration in the 0-8 microg/g range (R2 = 0.9992) with a 0.026 microg/g limit of detection. To screen OTC at 2 microg/g, the U.S. regulatory tolerance level, a threshold is established at x2-3sigma2, where x2 and sigma2 are the mean and standard deviation, respectively, of the TRL signals from 15 samples fortified at 2 microg/g. Among 45 blind samples randomly fortified at 0-4 microg/g, 41 were screened correctly and 4 negative samples were presumed positive. This method has the potential to improve throughput and save assay costs by eliminating acids, organic solvents, centrifugation, and filtration.

Validation of HPLC method for determination of tetracycline residues in chicken meat and liver

“…However, the clean up with liquid-liquid partitioning (LLP) was inefficient for tetracyclines (Table 2), due to their polar nature, unless ion pairs are formed. As well as, the organic solvents eliminated have harmful effects on human health and the environment (Chen, Smith, Qin, & Liu, 2006). So, solid phase extraction may be the chosen technique for the clean up of TCs extracted from biological matrixes.…”

Screening of Danofloxacin Residue in Bovine Tissue by Terbium-Sensitized Luminescence on C18 Sorbent Strips

“…18 A unique approach was developed previously in this laboratory that combined sorbent extraction and europium-sensitized luminescence (ESL) and later applied to screening of oxytetracycline (OTC) residue in catfish muscle. 19 The key element of this approach was a small-format (25 Â 10 mm) sorbent strip cut from a glassbacked C18 thin-layer chromatography (TLC) plate with the sorbent layer trimmed to 10 Â 6 mm in the center. This strip functioned as a reverse phase sorbent to carry out extraction, cleanup, and enrichment.…”

“…Fifteen C18 sorbent strips were securely clipped on a five-clip hanger, three per clip, as described previously. 19 The hanger was first lowered to immerse the strips in aqueous sample solutions for 30 min DANO adsorption, and then raised to allow extra water to drain to the strips' lower edges and absorbed by paper towel.…”

Development and Validation of Europium-Sensitized Luminescence (ESL) Method for the Determination of Tetracycline Residues in Milk

“…The photophysical properties of Eu(III)-TC complexes have recently been used for the determination of tetracycline in chicken and catfish muscle (Schneider and Chen 2004;Chen et al 2006) in biological fluids (Rodriguez-Diaz et al 2003). Europium complexes have been also used for the detection of human serum albumin in serum and urine (Jiang and Luo 2004) and for the determination of a variety of biomolecules spanning from DNA to enzymes (Peng et al 2006;Liu et al 1997).…”