Validation of a HPLC-MS/MS assay for the determination of total and unbound concentration of temocillin in human serum

• An HPLC-MS/MS assay is described to determine temocillin total and unbound concentrations in serum.
• The method is rapid, sensitive (LOQ = 1 mg/L), selective, precise and exact, with no interferences.
• The method was successfully applied to clinical samples.

ObjectivesThe aim of this study was to develop and validate a HPLC-MS/MS assay to determine total and unbound concentrations of temocillin in serum samples.Design and methodsMethanolic protein precipitation and ultrafiltration were used for total and unbound concentration extraction, respectively. Extract was injected into a LC-MS/MS system. Reversed phase chromatography was performed on a phenyl grafted column in gradient mode. Temocillin and internal standard (ticarcillin) were identified in positive electrospray ionization mode using ion transitions of m/z 415.34 > 339.1 and 385.31 > 160.3, respectively.ResultsTemocillin total and unbound concentration quantification assays were linear over concentrations ranging from 1 to 500 mg/L and from 0.5 to 300 mg/L, respectively. Both assays presented acceptable intra and inter-assay precision and accuracy < 13.9%. Limits of quantification and detection were of 1 and 0.10 mg/L, and 0.5 and 0.05 mg/L for total and unbound concentration respectively. Total temocillin concentration recovery ranged from 85.80 to 99.40%. Temocillin ion suppression effect was < 36.2 % in both assays.ConclusionThe method described is fast, sensitive and selective, with no interferences. This method may be used for both pharmacokinetic studies and therapeutic drug monitoring purposes.