1.
Jarmalavičienė, Reda, et al.
(author)
Coupling of solid-phase microextraction continuous bed (monolithic) capillaries with capillary zone electrophoresis for direct analysis of drugs in biological fluids.
2008
In: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 29:8, s. 1753-1760
Journal article (peer-reviewed) abstract
Hyperlink robust biocompatible solid-phase microextraction (SPME) devices were prepared using continuous bed (monolithic) restricted-access media (RAM) as the SPME capillary insert The RAM-based SPME approach was able to simultaneously separate proteins from a biological sample, while directly extracting the active components of caffeine, paracetamol and acetylsalicylic acid from the drug NeoCitramonum. The devices were interfaced with a CZE system and fully automated analysis for sample preconcentration, desorption, separation and quantification of analytes was evaluated. Comparative study of in-line coupled SPME-CZE using RAM and RP capillary inserts was carried out. Using an SPME (RAM) insert, the calculated caffeine, paracetamol and acetylsalicylic acid LODs in a bovine plasma sample were 0.3, 0.8 and 1.9 ng/mL, respectively.
2.
Jarmalaviciene, Reda, et al.
(author)
Restricted-access media development for direct analysis of drugs in biofluids using capillary liquid chromatography
2008
In: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 391:6, s. 2323-2328
Journal article (peer-reviewed) abstract
In analytical sciences the design of novel materials and stationary phases for the sample preparation and separation of analytes from biological fluids is needed. In this work we present different strategies for modification of stationary phases to produce tailored solutions for the analytical problem. In this context a novel shielded polymeric reversed-phase monolithic material was prepared in the presence of different numbers of reactive groups and concentrations of the coating polymer. Chromatographic experiments were performed using benzoic acid propyl ester in order to characterize the hydrophobicity and efficiency of the different restricted-access continuous beds prepared. Inverse size-exclusion chromatography was used for investigation of the pore structure properties of the beds. Capillary columns were applied for nanochromatography of biological fluids containing a mixture of nitrazepamum and medazepamum.
3.
Sundström, Ingela, et al.
(author)
Method development for identification of ketobemidone metabolites in microdialysate samples by coupled-column capillary liquid chromatography-tandem mass spectrometry
2008
In: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1189:1-2, s. 503-513
Journal article (peer-reviewed) abstract
Methodologies for identification of ketobemidone metabolites in microdialysate samples utilizing coupled-column capillary liquid chromatography-electrospray quadrupole time-of-flight tandem mass spectrometry are presented. Two different methods were developed to efficiently analyze the metabolites norketobemidone, ketobemidone N-oxide and hydroxyketobemidone, respectively. Both methods include on-line desalting and trapping of the analytes on micro-solid-phase extraction columns with different retention mechanisms. Norketobemidone and ketobemidone N-oxide were trapped on a C18 column and then eluted by back-flush followed by isocratic separation on a fluorinated reversed-phase type silica gel column (Fluofix). Retention equations are proposed for the chromatographic observations made on the Fluofix column. Hydroxyketobemidone was trapped on a phenylboronic acid column by complex formation at basic pH and then eluted at acidic pH directly into to the mass spectrometer. Oxidation of hydroxyketobemidone to its corresponding quinone was also observed. The methods were successfully used to analyze synthetic ketobemidone metabolites in dilute low-volume microdialysis samples
