J. Planar Chromatogr. 9, 84-91 (1996). Review of the use of tandem mass spectrometry (MS-MS) in combination with planar chromatography (TLC or HPTLC). Examples of the use of the technique with a wide range of synthetic compounds (drugs, plasticizers) and natural products (steroids, glycolipids) are provided. Ionization techniques for performing TLC-MS are described and critically appraised and practical aspects of the hyphenation of TLC and mass spectrometry are considered. Discussion of the advantages of MS-MS over simple MS techniques.

Talanta 42, 1553-1557 (1995). TLC on RP-18 with methanol - water 1:1, 1:3, 1:5. Analysis of amino acids that form colored compounds with reagents such as ninhydrin by spectrophotometry.

seed oils. J. High Resol. Chromatogr. 20, 315-320 (1997). TLC of oils and fatty acid methyl esters (FAME) on silica gel with hexane - ether 7:3 or 8:2. Detection by spraying with phosphomolybdic acid (5% in ethanol) and heating at 100°C. Preparative TLC on silica gel impregnated with 100% silver nitrate in acetonitrile, with hexane - ether - acetic acid 90:9:1. Detection by spraying with 2,7-dichlorofluorescein and under UV. Analysis by GLC after elution. Identification by GC/MS and IR.

GIT Fachz. Lab. 1, 14-18 (1999). TLC of hydroxybenzenes (pyrocatechol, resorcinol, phloroglucinol, hydroquinone, and pyrogallol) on conventional silica gel and specific Raman-TLC plates (coated with spherical silica gel) with toluene - methanol - acetic acid 45:16:4 in a saturated chamber. The spectra obtained by Raman spectroscopy enabled the use of data banks for the identification of substances. Typical detection limits are in the low microgram region per application.

J. Chinese Trad. & Herb. Drugs (Zhongcaoyao) 32 (4), 312-314 (2001). TLC on silica gel with chloroform - methanol - water 65:30:10. Detection by spraying with 10% sulfuric acid in ethanol and heating at 1058C for 5 min. Quantitation by spectrophotometry.

J. Planar Chromatogr. 17, 398-403 (2004). Review divided into several sections: ,Summaries’ contains a review of some recent research results in TLC-MS and PC-MS (use of a diode IR laser to desorb samples from a thin-layer chromatogram, with ionization of the desorbed gaseous molecules via a corona discharge; description of an interface between TLC and an electrospray ionization (ESI) mass spectrometer; ,on spot’ matrix-assisted laser desorption ionization (MALDI) mass spectrometry for TLC-MS); in ,Assessments and perspectives’ new results are detailed, precedent and new instrumental developments are previewed; in the section ,Interconnections’ synergies between mass spectrometry and different approaches to planar separations are explored. Finally, in ,Forecasts’ expectations and future developments, in addition to recent techniques, are described. 11 references.

Anal. Bioanal. Chem. 386, 1543-1551 (2006). Optimization of the plunger-based extraction device of Luftmann for HPTLC/MS coupling, which was originally designed for extraction on TLC aluminum foils. Some modifications enabled extraction of analytes from HPTLC/TLC glass plates. A buffering of the plunger reduced the occurrence of leakage. The involvement of a torque screwdriver for the fixation resulted in a reproducible contact pressure and avoided breaking the glass plates. HPTLC of two derivatization products, xanthylethylcarbamate (XEC) and dansylethylamide (DEA), on silica gel with acetone - n-hexane 1:4 and ethyl acetate, respectively. Quantitative determination by absorbance measurement at 233 nm (XEC) and fluorescence measurement at 366/>400 nm (DEA) before online extraction with ChromeXtractor interface connected to ESI mass spectrometer. For determination of the precisions of the extraction, selected ion monitoring in the ESI+ mode was used. For XEC the [M-NHCOOC2H5]+ signal at m/z 181 and for DEA the protonated molecule [M+H]+ at m/z 307 and the sodium adduct [M+Na]+ at m/z 329 were obtained. The overall mean repeatabilities (%RSD, n=7) were 18.6 % (XEC) and 8.7 % (DEA). The determination coefficient of the calibration function was established to be 0.9991 (XEC) and 0.9919 (DEA). The limits of detection calculated from the S/N of a 1-ng zone were 52 pg/zone (XEC) and 160 pg/zone (DEA). The employment of the interface for reduced plate thicknesses was also demonstrated. Repeatability of the extraction from glass plates, linearity of the signal obtained, and detection capability were shown to be comparable to the original device, which was only usable with aluminum foils.

J. Planar Chromatogr. 21, 11-14 (2008). Pressurized planar electrochromatography (PPEC) of 4-cholesten-3-one, 4-androsten-17beta-ol-3-one, 17alpha-acetoxyprogesterone, androstenedione, 2’-acetonaphthone, benzanilide, 2-nitroaniline, hydrocortisone, and benzamide on spherical RP-18 phase, cut into 3.3 x 12 cm sections. The mobile phase was 55 % aqueous acetonitrile containing 5 mM acetate buffer pH 4.7. The apparatus for PPEC has been described by Nurok et. al., Anal. Chem. 78, 2823-2832 (2006). Nine analytes were separated in 2 min. Detection by direct analysis of the TLC plate using DESI coupled to a tandem mass spectrometer.