Ultra-thin layer chromatography (UTLC) — A new dimension in thin-layer chromatography

High performance stationary phases for planar chromatography

“…Monolithic films of silica gel [13,81,82] or organic polymers [58,83,84] are thin, continuous biporous structures cast on a supporting surface. These structures do not require a binder to form a stable layer.…”

“…In this article we will present a contemporary picture of these intuitive advances in planar chromatography as they pertain to the kinetic performance of layers. Important milestones in the evolution of high performance stationary phases for planar chromatography were the early standardization of conditions for the preparation of plates for thin-layer chromatography (TLC) by Stahl [5]; the general phase out of selfmade layers with the introduction of pre-coated TLC plates around 1966; the redefinition of layer performance and the penetration of instrumentation into the practice of thin-layer chromatography with the launch of pre-coated high-performance thin-layer chromatography (HPTLC) plates in about 1975 [6][7][8]; the introduction of pre-coated chemically modified layers in about 1978, which facilitated an expansion in the range of applications suited to thinlayer chromatography [7][8][9][10]; the introduction of layers prepared from spherical particles around 1990 [11,12]; and more recently the introduction of ultra thin-layer chromatography (UTLC) based on monolithic films [13] or microfabricated structures [14]. In this article we will focus on the more recent developments in layer characteristics and attempts to define and optimize their structures, carrying forward only those aspects of earlier studies required to establish the improvements made.…”

Analysis of small molecules by ultra thin-layer chromatography-atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry

“…The development of miniaturized ultra-thin-layer chromatography (UTLC) [10] in addition to the development of other miniaturized analytical methods [11] is currently a hot topic in analytical chemistry. The UTLC method combined with UV or diode-array detection (DAD) provides faster elution times (1-6 min), lower solvent consumption (1-4 ml), and lower detection limits than those obtained when using the conventional TLC or HPTLC methods [12].…”

“…In those cases in which the standard compounds are not available (e.g., the screening of new natural agents or combinatorial chemistry samples), the identification of unknowns has to be performed using a specific technique, such as mass spectrometric detection. The combination of TLC and MS has been a very active research area over the last few years [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. TLC-MS has most frequently been performed as an off-line process in which the sample is scraped and extracted from the plate before MS analysis [5,22,23], or is analyzed as such with the use of various in situ techniques [15, 16, 19 -21, 24 -31], the most common of these being TLC-liquid secondary ion mass spectrometry (LSIMS), TLC-fast atom bombardment (FAB), TLC-matrix-assisted laser desorption/ionization (MALDI), and TLC-surface-assisted desorption/ionization (SALDI).…”

Recent Advances in the Analysis of Steroid Hormones and Related Drugs

“…85 An interesting study dealing with the reasons for and the elimination of the irreversible adsorption of some steroids during multiple development TLC merits mentioning. 86 A tandem TLC-HPLC method is described for screening cosmetic products for the presence of undeclared synthetic corticosteroids.…”