Analysis of a basic drug by on‐line solid‐phase extraction liquid chromatography/tandem mass spectrometry using a mixed mode sorbent

Abstract

Two on-line configurations using multiple 6- and 10-port valves were investigated for high-flow on-line extraction of a basic drug in rat plasma and human urine using a reversed-phase and a cation-exchange SPE sorbent. The first configuration studied was a single reversed-phase extraction cartridge (2.1 x 20 mm, 25 microm) using an optimized washing protocol. The results showed that up to 1.5 mL of sample (urine or plasma diluted 1:1) can be injected with limits of quantification (LOQs) as low as 100 pg/mL. The second configuration studied was the combination of a cation exchanger and a reversed-phase cartridge using at-column dilution. The results showed better LOQs than those obtained with the single cartridge at 10 pg/mL with the same injection volume. The mass spectrometer was operated in the multiple reaction monitoring (MRM) mode. All calibration curves gave an average of 5% relative standard deviation (RSD).

Two‐dimensional separation of peptides using RP‐RP‐HPLC system with different pH in first and second separation dimensions

“…It is theoretically possible to use at-column dilution [32,33] to reduce the organic content in fractions and feed them directly to the second separation dimension, but that is difficult to perform in capillary-or nano-LC scale. We have used the offline approach with partial evaporation of collected fractions prior to their injection on the second LC dimension with little difficulty.…”

Comparison of mixed-mode anion-exchange performance ofN-vinylimidazole-divinylbenzene sorbent

“…Restricted-access materials (RAM), which are silica-based materials intended for the analysis of small molecules in a complex matrix, could be a suitable option to clean up the sample, but not always to achieve sensitivity [10,11].…”

“…Therefore, these types of sorbents are promising materials for the net extraction of pharmaceuticals, pollutants, or many other types of compounds from complex matrices [11,[13][14][15]. Polymeric ion-exchange resins have a higher exchange capacity and a wider pH operating range than the classical silica-based ion exchangers [1].…”

Quantification des opiacés, cocaïniques et amphétaminiques par chromatographie liquide haute performance / spectrométrie de masse en tandem aprés préparation en ligne de l'échantillon

“…La chromatographie liquide couplée à la spectrométrie de masse, ou mieux, couplée à la spectrométrie de masse en tandem, a radicalement modifié l'approche de cette préparation. Ces dernières années, de nombreux travaux ont conjugué l'utilisation de grands débits sur des colonnes préparatives de grosse granulométrie (25-50 μm) et de « colonnes à accès restreints » [11,12]. Ces grosses particules autorisent de hauts débits de 2 à 4 mL/min (vitesse linéaire 8-10 cm/seconde) qui transforment le flux laminaire en flux turbulent (d'où la notion de turbulent flow chromatography, TFC) sans générer de pressions trop éle-vées : ce courant tourbillonnant facilite les transferts de masses entre les phases [13,14].…”

“…Les protéines ne pénètrent pas dans les pores et sont éluées pendant que les petites molécules y sont retenues. L'élution se fait généralement à contre-courant (back flush) vers la source du détecteur de masse ou vers une colonne analytique si une chromatographie préalable est nécessaire [11][12][13][14][15].…”