alphaHCH

AlphaHCH, or alpha-hexachlorocyclohexane, is one of the four stereoisomers of hexachlorocyclohexane (HCH). All HCH isomers share the same molecular formula, C6H6Cl6, and similar molecular weight, but differ in the arrangement of chlorine atoms around the cyclohexane ring. The alpha isomer is a distinct structural form among the alpha, beta, gamma, and delta isomers.

In industry, hexachlorocyclohexane is produced as a mixture known as technical HCH, often during the manufacture and purification of lindane (gamma-HCH). The alpha isomer commonly appears as a byproduct in technical HCH and is not typically used as the primary active ingredient in pest control. Gamma-HCH has historically been the main insecticidal isomer, while alphaHCH has been encountered as an impurity or residue in environmental samples.

AlphaHCH is a highly lipophilic, persistent organic compound. It has low water solubility and tends to accumulate in fatty tissues of organisms. Like other HCH isomers, it degrades slowly in the environment and can be transported long distances, leading to widespread distribution in soils, sediments, air, and biota. Its persistence, potential for bioaccumulation, and toxicity have contributed to regulatory scrutiny.

Regulatory status for alphaHCH mirrors that of related HCH isomers. Many countries restrict or ban the use of technical HCH and lindane due to environmental and health concerns. Internationally, the Stockholm Convention regulates lindane and related HCH isomers, with emphasis on reducing releases and restricting use, while allowing limited essential applications in some cases. Analytical monitoring of alphaHCH in environmental samples typically employs gas chromatography with mass spectrometry or electron capture detection.