Quantitative analysis of two opioid peptides in plasma by liquid chromatography–electrospray ionization tandem mass spectrometry

Analytical procedures for quantification of peptides in pharmaceutical research by liquid chromatography?mass spectrometry

“…MP1 was dissolved in the solvents indicated. After every 45 min storage at 10°C, 500 µL was transferred from one reaction vial to the next to measure 20 µL by RP-µHPLC-ESI-MS in full-scan mode of an ion-trap MS (LCQ classic, ThermoFinnigan) (a) initial concentration of MP1: 20 µg mL -1 in 0.1% TFA containing ACN: 29.8% (squares); 10.2% (triangles); and 0.4% (circles); (b) initial concentration of MP1: 20 µg mL -1 in 0.1% (v/v) TFA containing n-nonyl-β-D-glucopyranoside (w/v): 0.05% (diamonds); 0.03% (squares); 0.01% (triangles); and 0% (circles); (c) MP1 is dissolved in 30% (v/v) ACN, 0.1% TFA at initial concentrations of [µg mL -1 ]: 974.6 (diamonds); 55.0 (squares); 9.75 (triangles); and 5.5 (circles) evaporation with a stream of nitrogen [79] or by freezedrying (lyophilization). Automation for improved throughput is possible by using 96-well plates, which enable extraction of the smallest sample volumes in the microliter range [20,80].…”

“…Stable isotope-labeled peptides containing deuterated amino acids (e.g. Leu-d 10 or Phe-d 5 ) are used as internal standards, but their synthesis is costly and more reasonable alternatives are used [26,79,116]. The use of structurally related analogs available from earlier structure-activity relationship (SAR) studies during the pharmaceutical development process is often favored.…”

Quantitative analysis of the opioid peptide DAMGO in rat plasma and microdialysis samples using liquid chromatography–tandem mass spectrometry

“…The last decade several methods for quantifying peptides with LC-MS/MS have been published. The enkephalin analogs [(d-Ser 2 )Leu enkephalinThr 6 ), DADLE and DALDA has been quantified in plasma by using electrospray ionization or nanospray ion trap mass spectrometry [10][11][12]. Analytical methods for determination of the enkephalins Leu-and Met-enkephalin in microdialysis samples by LC-MS 2 , LC-MS 3 or in CSF using capillary LC-MS/MS has also been described [9,13,14].…”

Quantitative Analysis of a Synthetic Peptide, NR58-3.14.3, in Serum by LC-MS with Inclusion of a Diastereomer as Internal Standard

“…The quantitation of peptides in biological matrices by LC-ESI/MS/MS has been described as well (12,13). However, difficulties in reproducibility of the available methods were experienced that partially necessitated the use of multiple standard curves to cover the concentration range of interest.…”