Extraction and Determination of Cefazolin Sodium and Cefotaxime Sodium in Human Urine with a Weak Ion Exchange Monolithic Column

An online solid phase extraction (SPE) method was developed for the simultaneous screening of cefazolin sodium and cefotaxime sodium in human urine. A short weak anion exchange monolithic column was prepared and used as the selective extraction sorbent. The column exhibited good permeability and biocompatibility. During the online SPE process, most matrices in the urine samples were removed rapidly, while cefazolin sodium and cefotaxime sodium were effectively trapped in this monolithic column. Reversed phase high performance liquid chromatography (HPLC) was performed on a C18 column with ultraviolet detection at 254nm. The mobile phase consisted of methanol-0.005mol/L phosphate (21/79, v/v, pH=5.0) and the flow rate was set to 0.7mL/min. A good linear relationship was demonstrated at analyte concentrations ranging from 1 to 100g/mL. The absolute recovery ranged from 79.4% to 81.5% and the inter- and intra-day relative standard deviations were 5.0%. These results suggest that the online SPE-HPLC method is suitable for the simultaneous monitoring of cefazolin sodium and cefotaxime sodium in human urine samples because it avoids tedious pretreatments and provides a fast, economical, and reproducible method for assaying trace drugs in biological samples.