Ádám Zoltán Dávid

Fully on-line hyphenation of an experimental OPLC separation unit with diode-array detection and mass-spectrometry (OPLC-DAD-MS) for analysis of xanthine compounds

The newly developed experimental OPLC separation unit 100 (OSU 100) has been used for fully on-line multiple hyphenation using the one-channel flowing eluent wall (FEW) arrangement at the inlet. OSU 100-UV and OSU 100-DAD-ESI-MS with manual injector or autosampler were used to test the connected systems (OPLC-UV; OPLC-DAD-ESI-MS), using xanthine standards (caffeine, theophylline, theobromine) and green tea leaf extract as model compounds. The mobile phase chloroform-trifluoroacetic acid-acetonitrile-methanol, 76:4:6.67:13.33 (v/v) is suitable for rapid and selective separation, DAD, and ESI-MS of xanthines. The detection sensitivity of OPLC-UV or OPLC-DAD was increased by hyphenation with ESI-MS coupled in series. In contrast with DAD, the extracted ion chromatogram (m/z = 181.1 Da) after background subtraction yields readily measurable peaks from the small amounts of theophylline and theobromine in tea leaf extract. Analysis of xanthines was achieved within 10 min with less than 2 mL mobile phase. Owing to the openable adsorbent layer in OPLC the bed conditions can, moreover, be checked off-line after single or multiple fully online separations.

OPLC combined with NIR spectroscopy - A novel technique for pharmaceutical analysis

We report a new combination of overpressured-layer chromatography (OPLC) with near-infrared (NIR) spectroscopy for pharmaceutical analysis. Different pharmaceutical preparations containing caffeine, paracetamol, and acetylsalicylic acid as model compounds were separated by OPLC. The band density in the solid phase after OPLC was suitable for study of the separated components directly on the layer by NIR spectroscopy. We have demonstrated the applicability of rapid OPLC separation combined with UV densitometry and NIR spectroscopy for both qualitative and quantitative analysis. This OPLC—UV—NIR technique is thus suitable for rapid, nondestructive investigation of multicomponent pharmaceutical preparations and enables a different type of pharmaceutical analysis, e.g. starting-material tests, in-process control, end-product control, stability testing, etc. Another benefit of this newly developed combination of rapid off-line techniques is the possibility of simultaneous collection of qualitative and quantitative chromatographic and spectral information.

OPLC comparison of methods for aqueous extraction of Sennae folium and Tiliae flos plant samples

A new, simplified open-vessel microwave extraction (OVME) method has been used to prepare aqueous extracts of Sennae folium and Tiliae flos. For comparison, extracts were also prepared by classic pharmacopeial methods–decoctum, infusion, and ultrasound extraction. The extracts prepared by the different extraction methods were compared by over-pressured layer chromatography (OPLC), followed by video and UV-densitometric evaluation. We demonstrated the applicability of rapid OPLC separation combined with UV densitometry for comparison of extracts prepared by different methods. OPLC–UV is suitable for rapid, non-destructive investigation of multicomponent preparations of biological origin.