Extension of the application of the thermal in-situ reaction on NH2 layers to the detection of catecholamines in biological materials

Quantitative TLC-Image Analysis of Urinary Creatinine Using Iodine Staining and RGB Values

Digital image analysis of the separation results of colorless analytes on thin-layer chromatography (TLC) plates usually involves using specially tailored software to analyze the images generated from either a UV scanner or UV lamp station with a digital camera or a densitometer. Here, a low-cost alternative setup for quantitative TLC-digital image analysis is demonstrated using a universal staining reagent (iodine vapor), an office scanner and a commonly available software (Microsoft Paint) for analysis of red, green and blue colors (RGB values). Urinary creatinine is used as a model analyte to represent a sample in complicated biological matrices. Separation was carried out on a silica gel plate using a butanol-NH4OH-H2O (40 : 10 : 50, v/v) mobile phase with a 6-cm solvent front. It is important that the TLC plate be stained evenly and with sufficient staining time. Staining the TLC plate in a 23.4 × 18.8 × 6.8 cm chamber containing about 70 g iodine crystals yielded comparable results for the staining times of 30-60 min. The Green value offered the best results in the linear working range (0.0810-0.9260 mg/mL) and precision (2.03% RSD, n = 10). The detection limit was found to be 0.24 µg per 3 µL spot. Urinary creatinine concentrations determined by TLC-digital image analysis using the green value calibration graph agree well with results obtained from high-pressure liquid chromatography (HPLC).

Qualitative and quantitative analysis of hyaluronan oligosaccharides with high performance thin layer chromatography using reagent-free derivatization on amino-modified silica and electrospray ionization-quadrupole time-of-flight mass spectrometry coupling on normal phase

Purified oligomers of hyalobiuronic acid are indispensable tools to elucidate the physiological and pathophysiological role of hyaluronan degradation by various hyaluronidase isoenzymes. Therefore, we established and validated a novel sensitive, convenient, rapid, and cost-effective high performance thin layer chromatography (HPTLC) method for the qualitative and quantitative analysis of small saturated hyaluronan oligosaccharides consisting of 2-4 hyalobiuronic acid moieties. The use of amino-modified silica as stationary phase allows a simple reagent-free in situ derivatization by heating, resulting in a very low limit of detection (7-19 pmol per band, depending on the analyzed saturated oligosaccharide). By this derivatization procedure for the first time densitometric quantification of the analytes could be performed by HPTLC. The validated method showed a quantification limit of 37-71 pmol per band and was proven to be superior in comparison to conventional detection of hyaluronan oligosaccharides. The analytes were identified by hyphenation of normal phase planar chromatography to mass spectrometry (TLC-MS) using electrospray ionization. As an alternative to sequential techniques such as high performance liquid chromatography (HPLC) and capillary electrophoresis (CE), the validated HPTLC quantification method can easily be automated and is applicable to the analysis of multiple samples in parallel.

Metabolism of cymoxanil and analogs in strains of the fungus Botrytis cinerea using high-performance liquid chromatography and ion-pair high-performance thin-layer chromatography

The metabolism of cyano-oxime fungicide 1-(2-cyano-2-methoxyiminoacetyl)-3-ethylurea (cymoxanil) and analogs was studied on several strains of the fungus Botrytis cinerea owing to their difference in sensitivity towards cymoxanil. Chromatographic analysis of the unextracted culture medium was simpler and more accurate, particularly for ionizable metabolites because it avoids problems associated with extraction. Reversed-phase high-performance liquid chromatography was applied to compare the decrease of cymoxanil and analogs caused by different strains of B. cinerea, by periodic injections of incubated culture medium aliquots, directly on a C4 wide-pore column. Furthermore, a thin-layer chromatographic monitoring on C18 bonded silica gel with ion-pairing allowed the monitoring of the ionizable metabolites for substrates that were demonstrated to decompose most rapidly. These complementary analyses showed that the sensitivity of the highly sensitive strain towards cymoxanil was related to the disappearance of cyano-oximes studied from culture medium, namely to the ability of the strain B. cinerea to metabolize them.

Delta(2)-oxazolines-1,3 and N-acylaziridines as potential proinsecticides of carboxylic acids. V. Direct thin-layer chromatography monitoring of the metabolism in locust tissues

Modern thin-layer chromatography (TLC) was used for the evaluation of delta2-oxazolines-1,3 I and N-acylaziridine VII structures, as potential proinsecticides of carboxylic acids III. Thus the unmasking2 of the active principles III from delta2-oxazolines-1,3 Ia-c and N-acylaziridine VIIc was monitored by spotting aliquots directly onto RP-18 TLC plates, without any sample pretreatment during in vitro assays performed in concentrated locust tissues. To achieve a good separation of carboxylate IIIa from endogenous components of the tissues, a short preliminary development with methanol or ion-pairing was necessary. From UV-TLC chromatograms (densitograms) it appeared that in a phosphate buffer at pH 7.4, the oxazoline Ia with a C2 substituent devoid of alpha-ramification or alpha,beta-insaturation hydrolysed slowly into the corresponding beta-hydroxylamide VIa and intermediate aminoester Va. Significantly, locust mesenteron (or fat body) efficiently triggered the unmasking of IIIa, a transformation which corresponds to the expected proinsecticide behavior of Ia. Conducting TLC monitoring in the same locust tissues also revealed that the oxazolines Ib and Ic with an alpha-ramification and an alpha,beta-insaturation, respectively, cannot be considered as proinsecticides of the corresponding carboxylic acids IIIb and IIIc. In contrast, the N-acylaziridine VIIc appeared as a convenient proinsecticide structure for masking the carboxylic acid IIIc.