Enantioselective analysis of ketoprofen in human saliva by liquid chromatography/tandem mass spectrometry with chiral derivatization

Derivatization of carboxylic groups prior to their LC analysis - A review

Carboxylic acids (CAs) represent a large group of important molecules participating in various biologically significant processes. Analytical study of these compounds is typically performed by liquid chromatography (LC) combined with various types of detection. However, their analysis is often accompanied by a wide variety of problems depending on used separation system or detection method. The dominant ones are: i) poor chromatographic behavior of the CAs in reversed-phase LC; ii) absence of a chromophore (or fluorophore); iii) weak ionization in mass spectrometry (MS). To overcome these problems, targeted chemical modification, and derivatization, come into play. Therefore, derivatization still plays an important and, in many cases, irreplaceable role in sample preparation, and new derivatization methods of CAs are constantly being developed. The most commonly used type of reaction for CAs derivatization is amidation. In recent years, an increased interest in the isotopic labeling derivatization method has been observed. In this review, we comprehensively summarize the possibilities and actual trends in the derivatization of CAs that have been published over the past decade.

Simultaneous quantification of nineteen Non-Steroidal Anti-Inflammatory Drugs in oral fluid by liquid chromatography - high resolution mass spectrometry. Application on ultratrail runner's oral fluid

Non-steroidal anti-inflammatory drugs (NSAIDs) are a therapeutic class suspected to be used by ultratrail runners. The use of NSAIDs during ultratrails is known to be associated with various adverse effects. To study the prevalence of NSAIDs intake in ultratrail runners, oral fluid (OF) is a relevant matrix as it is noninvasive and easy to collect. The aim of our work was to develop and validate a liquid-liquid extraction followed by a LC-MS/HRMS method for the simultaneous quantification of nineteen NSAIDs in OF. After a comparison of different liquid-liquid extraction methods, a double step liquid-liquid extraction with chloroform was performed on OF collected with Quantisal®, with extraction recoveries higher than 90 %. An Accucore AQ column was selected for the chromatographic separation of NSAIDs. The Q Exactive Plus mass spectrometer operated in full scan and ddms2 mode after positive and negative electrospray ionization. Selectivity, carry-over, matrix effect, and linearity were validated for all NSAIDs. Within-day and between-day accuracy and precision were validated for all NSAIDs (< 15 % for QC samples and < 20 % for LLOQ), except within-day accuracy for the LLOQ of mefenamic acid. A stability study was also performed on OF at room temperature and +4 °C. The method was applied on OF from runners who participate to Ultra Trail du Mont-Blanc®.

(S)-1-(5-(4-Methylpiperazin-1-yl)-2,4-dinitrophenyl)pyrrolidine-2-carboxylic acid as a derivatization reagent for ultrasensitive detection of amine enantiomers by HPLC-MS/MS and its application to the chiral metabolite analysis of (R)-1-aminoindan in saliva

(S)-1-(5-(4-Methylpiperazin-1-yl)-2,4-dinitrophenyl)pyrrolidine-2-carboxylic acid (Pro-PPZ) was employed as a chiral derivatization reagent (CDR) for the efficient enantioseparation and ultrasensitive mass spectrometric detection of chiral amines. Pro-PPZ was prepared from the one-step reaction of 1-(5-fluoro-2,4-dinitrophenyl)-4-methylpiperazine (PPZ) and l-proline. Two amines and two amino acid methyl esters were selected as model chiral amines, which were easily labeled with Pro-PPZ under mild reaction conditions (35 °C for 10 min) generating Pro-PPZ-amine derivatives. The resulting diastereomers were completely separated by reversed-phase liquid chromatography (RP-LC) using an ODS column (R_s = 3.4-17.0 for amines). Ultrasensitive detection limits on femtomolar level were obtained for the tested amines using multiple reaction monitoring (MRM) chromatograms at a single monitoring ion, m/z 289 (0.1-5.0 fmol for amines). The practical metabolite analysis of (R)-1-aminoindan (R-AI) in saliva samples was performed by LC-MS/MS using the Pro-PPZ derivatization method. The method was validated in terms of precision, accuracy, and linearity. Using this method, R-AI concentrations in saliva were determined after a single oral administration of the drug rasagiline to healthy male and female subjects, but no (S)-1-aminoindan (S-AI) was detected, which suggesting that R-AI was not converted into S-enantiomer in the metabolic process. R-AI concentrations in four healthy volunteers ranged from 32.85 nM to 49.45 nM, with an average value of 43.76 nM. To date, there is no LC-MS (or MS/MS) method reported for the enantioselective determination of R-AI in human saliva samples.

Derivatization procedures and their analytical performances for HPLC determination in bioanalysis

Derivatization, or chemical structure modification, is often used in bioanalysis performed by liquid chromatography technique in order to enhance detectability or to improve the chromatographic performance for the target analytes. The derivatization process is discussed according to the analytical procedure used to achieve the reaction between the reagent and the target compounds (containing hydroxyl, thiol, amino, carbonyl and carboxyl as the main functional groups involved in derivatization). Important procedures for derivatization used in bioanalysis are in situ or based on extraction processes (liquid-liquid, solid-phase and related techniques) applied to the biomatrix. In the review, chiral, isotope-labeling, hydrophobicity-tailored and post-column derivatizations are also included, based on representative publications in the literature during the last two decades. Examples of derivatization reagents and brief reaction conditions are included, together with some bioanalytical applications and performances (chromatographic conditions, detection limit, stability and sample biomatrix).