A New Chromogenic Spray Reagent for the Detection and Identification of 2,4-Dichlorophenol, an Intermediate of 2,4-D Herbicide in Biological Material by High-Performance Thin-Layer Chromatography

Summary

2,4-Dichlorophenoxyacetic acid (2,4-D) is a phenoxy group of herbicide used worldwide. As it is extensively used, it has consequential problems on living beings. 2,4-D is degraded into the chlorinated phenols and catechols, and these phenol compounds are more hazardous than the parent 2,4-D herbicide. In this paper, an attempt is made to detect 2,4-dichlorophenol in 2,4-D poisoning cases from human viscera. Sensitive and selective detection of 2,4-dichlorophenol using high-performance thin-layer chromatography (HPTLC) is possible by coupling it with 4-amminoantipyrene in the presence of potassium ferricyanide. Standard 2,4-dichlorophenol and human visceral extract are allowed to run on an HPTLC plate with hexane, acetone, and ethyl acetate as the mobile phase. Mechanistically, 4-amminoantipyrene reacts with 2,4-dichlorophenol in the presence of potassium ferricyanide to form p-quinoneimide which is brick red in color. This known reaction is, for the first time, applied to detect 2,4-dichlorophenol in 2,4-D poisoning cases from human viscera. The formation of brick red color spot on the HPTLC plate allows the easy and confirmed detection of 2,4-d ichlorophenol in 2,4-D poisoning case. This HPTLC method is simple and easy to work in laboratory. The reagents do not react with the parent 2,4-dichorophenoxyacetic acid and other organophosphorus, organochlorine, carbamate, and pyrethroid insecticides, i.e., these reagents are specific. The constituents of the viscera (amino acids, peptides, proteins, etc.) and plant material do not interfere with the reagents. The presence of 2,4-dichlorophenol in the same visceral sample is confirmed by gas chromatography—mass spectrometry (GC—MS). The detection limit of reagents for 2,4-dichlorophenol is approximately 0.5 μg.