Tetracyclines sample preparation

The same test kit has been also applied to detect all members of the tetracycline group of antibiotics in kidney and meat tissue (72), although its crossreactivity varied from 4-5% for oxytetracycline and doxycycline to 100% for tetracycline and chlortetracycline. However, the applied sample preparation procedure... 

Sample preparation Bulk. Prepare a 10 mg/mL solution of tetracycline hydrochloride in water, inject a 20 pL aliquot. Prepare a 10 mg/mL solution of tetraQrcline in 100 mM HCl, inject a 20 xL aliquot. Formulations. Shake 500 mg capsule blend with 15 mL water and 1 mL concentrated ammonia until solid has dissolved, make up to 50 mL with pH... 

In 2008, Carretero et al. described a multi-class method for the analysis of 31 antibacterials (including f)-lactams, macrolides, lincosamides, quinolones, sulfonamides, tetracyclines, nitroimidazoles, and trimethoprim) in meat samples by PLE-LC-MS/MS. Meat samples were homogenized and blended with EDTA-washed sand, then extracted with water by applying 1500 psi (Ib/in. ), at 70°C. One extraction cycle was 10 min. A drawback of the method is the large volumes of extracts (40 ml) obtained, which required evaporation to concentrate the extract volume prior to final analysis. This evaporation step considerably increases the time required for sample preparation. The proposed method has been applied to the analysis of 152 samples of cattle and pig tissues, with the presence of quinolones, tetracyclines, and sulfonamides detected in 15% of the samples, although at concentrations below the MRLs. 

Turnipseed et al. described a method for the multi-class residue determination of P-Iactams, sulfonamides, tetracyclines, fluoroquinolones, and macroiides in milk and other dairy products. The sample preparation combines extraction with acetonitrile, clean-up with Oasis HLB cartridges, and ultrafiltration using molecular weight cut-off filters to improve the overall performance of the analysis. Acceptable recoveries were obtained for sulfanomides, macroiides, and quinolones (>70%) however, recoveries were rather low for tetracyclines (50-60%) and P-lactams (<50%). Despite the extensive clean-up procedure, significant matrix ion suppression was observed for many compounds, making it necessary to include matrix-matched calibration standards for quantification purposes. 

Three tetracycline antibiotics (tetracycline, minocycline, demeclocycline) were isolated from serum and separated on a Cg column (A = 350 nm) using a 91/7/2/0.1 water/acetonitrile/methanol/TFA mobile phase [1349]. The authors noted that samples prepared in methanol exhibited severe peak fronting, whereas those made up in the mobile phase produced symmetric peaks. Note that the optimal situation... 

Procedure Distribute into identical test-tubes an equal volume of standard tetracycline solution and the sample to be examined (having presumed equal concentrations) and add to each tube an equal volume of inoculated nutrient medium (for instance 1 ml of the solution and 9 ml of the medium). Prepare at the same time two control tubes without the chlortetracycline, one containing the inoculated medium and the other identical with it but treated immediately with 0.5 ml of formaldehyde solution. These tubes are used to set the optical apparatus employed to measure the growth. 

Paper partition chromatographic methods have been widely applied to the analysis of tetracyclines (128, 129). Pharmaceutical aqueous suspensions for oral use are acidified with HC1 and diluted with methanol. Crystalline formulations are dissolved only in methanol. A paper chromatographic method for TC determination in pharmaceutical preparations is based on the complexation of the antibiotic with a mixture of urea and disodium edetate on paper at pH 7.4. Urea helped in the separation of degradation products and led to the formation of well defined spots (130). Samples from fermentations must be acidified with oxalic acid to liberate TC from the mycelium. TC in filtrates may be precipitated in saturated solution of sodium tetraphenyl borate, precipitate dissolved in ethyl or butyl acetate and applied for paper chromatography. Various solvent systems and hRp values for paper chromatography are given in Table 4. 

Cennamo et al. [103] developed a SPR based sensor with a MIP layer of about 150 nm. This sensor was able to specifically recognize L-nicotine and not D-nicotine at a low concentration relevant for samples in the field. Other examples of MIP based SPR sensors are the sensor by Verma and Gupta [104] detecting the antibiotics tetracycline and their vitamin B3 sensor [105] for which the MIPs were prepared in hydrogel. Lotierzo et al. [106] developed an SPR based sensor for domoic acid, a neurotoxin. They compared their sensor with a sensor based on monoclonal antibodies and found that the MIP based sensor could be regenerated without losing its functionality and had a three times lower detection limit compared to the immunosensor. 

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