Development of A Fast Method for Direct Analysis of Intact Synthetic Insulins in Human Plasma: The Large Peptide Challenge

Abstract

A simple SPE LC-MS analysis was developed for direct, simultaneous quantification of insulin glargine, detemir, aspart and glulisine.

Improved sensitivity of the nano ultra-high performance liquid chromatography-tandem mass spectrometric analysis of low-concentrated neuropeptides by reducing aspecific adsorption and optimizing the injection solvent

“…The presence of a carrier protein, such as BSA, in the dilution solvent can reduce adsorption of peptides at surfaces by occupying the nonspecific binding sites of materials used during standard preparation [23,39]. However, when adding 40 g mL −1 of BSA to the optimal dilution solvent (water/FA 95/5 V/V) aspecific adsorption of NT, NMB and NMN is not influenced in a regular Eppendorf tube (data not shown).…”

“…Due to aspecific adsorption of peptides to material used during standard preparation (pipette tips, Eppendorf tubes and UHPLC vials), the limit of quantification of the method is drastically affected [19,20]. In addition, it has been shown that the adsorption phenomenon is the main cause of poor repeatability and non-linearity in quantitative analyses of low-concentrated peptides [21][22][23][24]. Although stable isotope-labeled internal standards are able to correct for these two issues, they cannot correct for the loss of peptides due to adsorption.…”

“…Since a beneficial effect of organic solvent and/or acid on aspecific adsorption has already been reported [22][23][24]27], the influence of different solvents on the responses of our peptides of interest is evaluated using a fractional factorial design. The most influencing solvents are further fine-tuned in a central composite design and the optimal experimental conditions are predicted using Derringer multi-response methodology [28].…”

Practical Applications of Integrated Microfluidics for Peptide Quantification

“…The final gradient condition for insulin analysis was a linear gradient ramp from 25-55% B in 5 min. At analytical (2.1mm ID) scale, the literature [19,20,22,23] suggests that either a 300 Å pore size and/or positively charged surface particle columns might provide a further enhancement in sensitivity and peak shape. Therefore three 150 μm × 50 mm iKeys were compared under constant gradient conditions to rapidly confirm stationary phase choice.…”

An Ultrasensitive Nano UHPLC–Esi–MS/MS Method for The Quantification of Three Neuromedin-Like Peptides in Microdialysates

“…For peptide analytes, it has been shown that both flow rate and solvent composition influence the relative abundances of the precursor ions formed [43,44]. Therefore, 1 μM standard solutions of NT, NMB and NMN, prepared in the solvent in which the peptides more or less elute, water/ACN/FA (50/50/0.1 V/V/V), are infused into the nano source at 300 nl/min, the flow rate used for separation.…”