Clean and rapid liquid chromatographic technique for monitoring of oxytetracycline and sulphadimidine in milk without use of organic solvents

Analysis of sulphonamide residues in edible animal products: A review

The methods of analysis for sulphonamide residues in edible animal products are reviewed. Sulphonamides are widely used for therapeutic and prophylactic purposes in both humans and animals, sometimes as growth promoters as additives in animal feed. As a result of their widespread use, there is concern about whether the levels used of these drugs can generate serious problems in human health, e.g., allergic or toxic reactions. Several methods for the determination of sulphonamides have been reported in the literature and this review considers high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC/MS), gas chromatography (GC), thin-layer chromatography (TLC), high-performance capillary electrophoresis (HPCE), enzyme-linked immunosorbant assay (ELISA), biosensor immunoassay (BIA) and microbiological methods. Specific aspects of analysing sulphonamides, such as sample handling, chromatographic conditions and detection methods are discussed. Methods for drug residue monitoring should be accurate, simple, economical in both time and cost, and capable of detecting residues below the maximum residue limits (MRL). The current sulphonamide detection technologies are based on chromatographic methods or bacteriological growth inhibition. The instrumental methods such as HPLC and GC are both sensitive and specific, but are laborious and expensive. Because of the labour-intensive processes, only a few cases of GC methods applied to residue analysis have been published. These methods are suitable for confirmation but not for screening of large numbers of samples. Microbiological methods do not require highly specialized and expensive equipment. They also use highly homogeneous cell populations for testing and thus result in better assay precision. Although HPCE has powerful separation ability, the precision is poor and the instrument still needs to be improved. To date, this technique has not been widely applied to routine analysis. Currently, TLC has been almost replaced by other instrumental analysis. A rapid, sensitive and specific assay is required to detect positive samples in routine analysis, which can then be confirmed for the presence of sulphonamides by HPLC. Immunochemical methods such as ELISA can be simple, rapid and cost-effective, with enough sensitivity and specificity to detect small molecules. This review can be considered as a basis for further research aimed at identifying the most efficient approaches.

Monitoring of five sulfonamide antibacterial residues in milk by in-tube solid-phase microextraction coupled to high-performance liquid chromatography

A simple, rapid, and sensitive method for the quantitative monitoring of five sulfonamide antibacterial residues in milk was developed by coupling in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography with an ultraviolet detector. A poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column was selected as the extraction medium for this on-line technique. To obtain optimum extraction efficiency, several parameters relating to in-tube SPME were investigated. By simple extraction with ethanol, dilution with phosphate buffer solution, and centrifugation, the sample solution then could be directly injected into the device for extraction. The calculated detection limits for sulfadiazine, sulfamethazine, sulfamethoxazole, sulfamonomethoxine sodium, and sulfacetamide sodium were 2.0, 2.8, 1.7, 2.5, and 22 ng/mL, respectively. The method was linear over the range of 20-5000 ng/mL (100-5000 ng/mL for sulfacetamide sodium) with a correlation coefficient R (2) value >0.9980. Excellent method reproducibility was found by intra- and interbatch precisions, yielding the relative standard deviations of <10.0 and <9.94%, respectively. The proposed method was proved to be robust in monitoring sulfadiazine, sulfamethazine, sulfamethoxazole, sulfamonomethoxine sodium, and sulfacetamide sodium residues in milk.

Complexities in tetracycline analysis—chemistry, matrix extraction, cleanup, and liquid chromatography

The extraction and cleanup of commonly used tetracyclines (oxytetracycline, tetracycline, chlortetracycline, and doxycycline) from sample matrix, and their subsequent determination via liquid chromatography can be problematic. Many manuscripts report on various challenges encountered when developing a method for tetracycline antibiotics determination. These complexities often result in less than perfect recoveries or chromatograms and are based on the underlying chemistry associated with tetracyclines. This review compiles, compares, and discusses the results and observations found in published methods, while focusing on chemical principles in order to increase the practicing chemist's understanding of TCs to aid him/her in developing useful analyses.

Application of shielded column liquid chromatography for determination of sulfamonomethoxine, sulfadimethoxine, and their N4-acetyl metabolites in milk

A hazardous-chemical free method for simultaneous determination of sulfamonomethoxine (SMM), sulfadimethoxine (SDM), and their N4-acetyl metabolites in raw milk using shielded column liquid chromatography is developed. The target analytes are extracted by mixing with ethanol-acetic acid (97:3, v/v) followed by centrifugation. The procedure uses a Hisep shielded hydrophobic phase (SHP) column, isocratic elution with 0.1% acetic acid solution (pH 3.1, in water)-ethanol (75:25, v/v), and a photo-diode array detector. Average recoveries from samples spiked at 25-500 ng/ml for each drug were >81% with relative standard deviations within 5%. The limits of quantitation were <25 ng/ml.