title: Development of a fast method for direct analysis of intact synthetic insulins in human plasma: the large peptide challenge.
abstract: BACKGROUND
  Intact insulins are difficult to analyze by LC-MS/MS due to nonspecific binding and poor sensitivity, solubility and fragmentation. This work aims to provide a simpler, faster LC-MS method and focuses on solving the above issues.
  
  
  RESULTS
  A novel charged-surface chromatographic column produced peak widths for insulin that were significantly narrower than traditional C18 columns when using formic acid as mobile phase. Mass spectral fragments m/z >700 provided greater specificity, significantly reducing endogenous background. Detection limits in human plasma were 0.2 ng/ml for insulin glargine, glulisine and detemir, and 0.5 ng/ml for insulin aspart. Average accuracy for standard curve and QC samples was 93.4%.
  
  
  CONCLUSIONS
  A simple SPE LC-MS analysis was developed for direct, simultaneous quantification of insulin glargine, detemir, aspart and glulisine.
authors.affiliation: Institute of Pharmaceutical Sciences, King's College London, Franklin-Wilkins Building, London, UK. erin_chambers@water.com
authors.forename: Erin E
authors.initials: EE
authors.lastname: Chambers
authors.forename: Cristina
authors.initials: C
authors.lastname: Legido-Quigley
authors.forename: Norman
authors.initials: N
authors.lastname: Smith
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Fountain
mesh_terms: D000595:Amino Acid Sequence; D053000:Analytic Sample Preparation Methods; D001774:Blood Chemical Analysis / Q000379:methods*; D002138:Calibration; D002853:Chromatography, Liquid; D006801:Humans; D061385:Insulins / Q000097:blood* / Q000138:chemical synthesis / Q000737:chemistry*; D057230:Limit of Detection; D008403:Mass Screening; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011786:Quality Control; D020349:Surface Plasmon Resonance; D013997:Time Factors
chemical_list: D061385:Insulins