On-line sample treatment - Capillary gas chromatography

Sample pretreatment is often the bottleneck of a trace level analytical procedure. In order to increase performance, increasing attention is therefore being devoted to combining sample pretreatment on-line with the separation technique that has to be used. In the present review, a variety of procedures in use today for sample treatment coupled on-line to capillary gas chromatography (GC) is briefly discussed. Special attention is devoted to coupled-column techniques such as SPE-GC and LC-GC (SPE, solid-phase extraction; LC, column liquid chromatography) which are topics of much current interest, also because of their frequent use in so-called hyphenated systems

On the coupling of fluorescence line-narrowing spectroscopy and poly(ethylene)imine-cellulose thin-layer chromatography

The feasibility of a direct coupling of the low-temperature, high-resolution, fluorescence line-narrowing spectroscopy (FLNS) technique and the autoradiographic 32P -post-labelling technique for DNA adducts is explored. FLNS has been used to identify analytes on various types of thin-layer chromatography (TLC) plates, but not on poly(ethylene)imine-cellulose (PEI-cellulose) TLC sheets involved in the 32P -post-labelling technique which includes a two-dimensional separation. PEI-cellulose was found to exhibit a high fluorescence background. Its fluorescence excitation and emission characteristics were studied in detail and the signal-to-noise ratios of the FLNS spectra were optimized using background subtraction, time-resolved detection and a new synchronous scanning procedure. Benzo[a]pyrene (B[a]P) tetrols and a standard B[a]P–DNA adduct were used as model compounds. Limits of detection were in the low-picomole range. The technique was applied for the identification of spots extracted from PEI-cellulose TLC sheets obtained after a 32P -post-labelling procedure of DNA containing B[a]P adducts at a level of two adducts per hundred bases