title: Molecularly imprinted solid phase extraction-pulsed elution-mass spectrometry for determination of cephalexin and alpha-aminocephalosporin antibiotics in human serum.
abstract: A highly selective molecularly imprinted solid phase extraction (MISPE)-pulsed elution (PE) method coupled with electrospray mass spectrometry (MS) was developed for the rapid screening and determination of cephalexin in alpha-aminocephalosporin antibiotics. This method involved the solid phase extraction of cephalexin using a molecularly imprinted polymer micro-column, and pulsed elution with 1% trifluoroacetic acid in methanol, which contains sulindac as an internal standard for enhanced precision in MS detection. An LC/MS spectrometer was operated in the positive electrospray mode, and the selected-ion-recording (SIR) function was employed to detect the molecular ions of cephalexin, cefradine, cefadroxil and sulindac at m/z 348, 350, 363 and 357. Linearity was achieved in the cephalexin concentration range from 0.3 to 25microg/ml (or 5-500ng) (R(2) = 0.998). The detection limit was estimated at 0.04microg/ml (or 0.8ng) of cephalexin. Advantages of the newly developed MISPE-PE-MS, over the previously reported MISPE-DPE-FPE-UV, were evidenced in terms of detection limit, analysis time, solvent consumption, and simplicity of method development.
authors.affiliation: Chemistry Department, Carleton University, Ottawa, Canada K1S 5B6.
authors.forename: Stanley G
authors.initials: SG
authors.lastname: Wu
authors.forename: Edward P C
authors.initials: EP
authors.lastname: Lai
authors.forename: Paul M
authors.initials: PM
authors.lastname: Mayer
mesh_terms: D002506:Cephalexin / Q000097:blood* / Q000737:chemistry; D002511:Cephalosporins / Q000097:blood* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods
chemical_list: D002511:Cephalosporins; D002506:Cephalexin