Which reagent is used in thin-layer chromatography (TLC) to extract cocaine metabolites from urine?

In thin-layer chromatography (TLC), the extraction of cocaine metabolites from urine often involves the use of alkali and organic solvent because this combination is effective in breaking down the metabolites into forms that can be better separated and analyzed.

The alkali helps to ionize and solubilize the basic components of the cocaine metabolites, allowing them to be more readily dissolved in the organic solvent. This solubility is crucial for effective migration on the TLC plate, as the interaction between the compound and the stationary phase depends heavily on the chemical properties of the metabolites. Organic solvents typically used in conjunction with alkali can help in efficiently extracting the metabolites from the complex matrix of urine.

Using methods involving these reagents optimizes the extraction process, facilitating a clearer and more distinct separation of the metabolites on the TLC plate for further analysis.