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.
A poly(methacrylic acid-ethylene glycol dimethacrylate, MAA-EGDMA) monolithic capillary was used for the direct and on-line extraction of telmisartan from Sprague-Dawley rat tissue (heart, kidney, and liver) homogenates. Under optimized conditions, the tissue homogenates were simply diluted with a mixture of phosphate buffer (pH 2)/ACN (90:8 v/v), and then injected for extraction only after centrifugation and filtration. Coupled to HPLC with fluorescence detection, the method was linear over the range of 1.25-1500 ng/g for telmisartan in heart and kidney, 12.5-15 000 ng/g in liver with correlation coefficients over 0.9992. The detection limits were found to be in the range from 0.24 to 1.8 ng/g. RSDs for intra- and inter-day ranged from 1.2 to 8.1%. The determination of telmisartan in treated rat tissues was achieved by using the proposed method.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.