On-line In-Tube Solid Phase Microextraction coupled to Capillary Liquid Chromatography-Diode Array Detection for the analysis of caffeine and its metabolites in small amounts of biological samples

Publication date: Available online 7 October 2019Source: Journal of Pharmaceutical and Biomedical AnalysisAuthor(s): H.D. Ponce-Rodríguez, A.A. García-Robles, P. Sáenz-González, J. Verdú-Andrés, P. Campíns-FalcóAbstractIn-tube solid phase microextraction (IT-SPME) coupled on-line to capillary liquid chromatography with diode array detection provides a simple and fast analytical methodology for the simultaneous quantitation of caffeine and its three primary metabolites (theobromine, paraxanthine and theophylline) in micro samples of serum, saliva and urine matrices. The sample amount required for one analysis was only 2.5 µL of saliva, 6.25 µL of serum or 40 µL of urine, a requirement for its implementation in a hospital laboratory for preterm newborns, where sample availability is a major problem. In standard conditions, 25 µL of diluted saliva or serum (or 100 µL of urine) were processed by IT-SPME in 30 cm of commercially available capillary GC column coated with ZB-FFAP (100% nitroterephthalic modified polyethylene glycol). The retained compounds were desorbed from the IT-SPME capillary by the mobile phase (a gradient mixture of water and methanol) and the separation was carried out in a C18 column (150 mm × 0.5 mm i.d., 5 µm particle size). Analytes eluted before 14 minutes, at a flow rate of 15 µL min−1, and were detected by absorbance at 275 nm. The calibration graphs presented good linearity (R2 > 0.99), without the p...
Source: Journal of Pharmaceutical and Biomedical Analysis - Category: Drugs & Pharmacology Source Type: research