Detection of multiple anions by thin-layer chromatography

A novel detection method for 21 different anions by thin-layer chromatography is presented. Anions on the target plate form salts with amine in a developing solvent and are visualized after staining with citric acid-acetic anhydride reagent as white spots contrasting against a pale red-pink background. This method has particularly high sensitivity for anions of chlorate, sulfate, phosphate, chromate and dichromate (0.02-0.05 microg). The method is demonstrated to efficiently detect toxic arsenite in curry sauce as an example application. The proposed method offers highly efficient indirect detection for a wide range of anions, and serves as a purification procedure for the preparation of anionic sample solutions for other analytical methods.     

Comparison of phenolic content and antioxidant activity of Actaea racemosa L. and Actaea cordifolia DC

Actaea racemosa L. is used as a component of drugs or dietary supplements to alleviate the menopause symptoms. Its biological activity is associated with the presence of phenolic compounds. In our work, the analysis of isoflavones and phenolic acids – caffeic acid (CA), ferulic acid and isoferulic acid (iFA) – both free and bonded in two species of Actaea, was conducted using HPLC-PAD technique. Moreover, the antioxidant effect of extracts from different parts of the investigated plants was determined on the basis of DPPH assay. Significant variation of CA and iFA content was observed. The highest content of CA was found in A. racemosa, while Actaea cordifolia contained the highest amount of iFA. Isoflavones were not found in the investigated plants. The antioxidant activity assay showed the high free radical-scavenging ability of the extracts obtained from different parts of the plant.     

Trace metal analysis by combined thin-layer chromatography and reflectance spectroscopy

Traces of nickel, cobalt and copper are separated on chromatoplates and, after reaction with rubeanic acid, are determined quantitatively by diffuse reflectance spectroscopy ; 0.05 μg of the elements can be determined with a probable percentage error of 2 to 5%. Temperature stability, aging, and pH dependence of the chelates and chelating agents in the adsorbed state were investigated. The method is simple and could find routine application in geochemistry, food analysis, etc.     

Detection and determination of N-nitrosamino acids by thin-layer chromatography using fluorescamine

A novel procedure is described for the detection and determination of N-nitrosamino acids (NAAs) on activated silica gel thin-layer chromatographic plates. N-Nitrososarcosine, N-nitrosoproline, and N-nitroso-4-hydroxyproline could be detected as fluorophors at the 200-pmole level (20-30 ng) after being irradiated with ultraviolet light and sprayed with fluorescamine reagent. Spectrophotometric determination of the relative fluorescence of 0.4-40 nmoles of NAAs gave rise to similar calibration curves when plotted on a log-log scale. An application of this method to the detection of NAAs in uncooked bacon is described.     

Detection and determination of N-nitrosamines by thin-layer chromatography using fluorescamine.

A novel procedure is described for the detection and determination of N-nitrosamines (NAs) on thin-layer chromatographic plates. Ultraviolet irradiation of NAs on activated plates (silica gel or aluminum oxide) yields primary or secondary amines, which after spraying with fluorescamine reagent give fluorescent or non-fluorescent products, respectively. The majority of the 24 NAs examined afforded NAs, although the volatile dimethyl-, diethyl- and pyrrolidine-N-nitrosamines gave limits of 500, 40, and 40 ng, respectively. Spectrophotometric determinations of the relative fluorescence of 0.1-40 nmoles of NAs gave rise to nearly linear calibration curves when plotted on a log-log scale.     

Detection of sodium alkanesulphonates and alkylbenzenesulphonates by polyamide thin-layer chromatography.

A thin-layer chromatographic method was investigated in which two series of sodium alkanesulphonates (C4-C18) and alkylbenzenesulphonates (C0-C14) were separated. All of the compounds tested were clearly separated on polyamide layers with aqueous ammonia-pyridine and aqueous ammonia-pyridine-methanol systems and detected with high sensitivity by spraying with a pynacryptol yellow reagent and then observing under UV light (253.6nm).     

Separation of amphotericin B components by combined thin-layer and high-performance liquid chromatography

Amphotericin B has been separated into five components by the use of thin-layer chromatography (TLC) with only methanol as the developing solvent. Each TLC component was then subjected to high-performance liquid chromatography. Besides the two major components found in other studies, amphotericin B was also found to contain five other significant heptaenes, one tetraene, two fluorescent polyenes (pentaene and heptaene), and at least five other significant components which had appreciable absorbance at approximately 305 nm. In addition, amphotericin B was found to exhibit as in a previous study by other workers, only a trace amount of fluorescence.