Journal of Analytical Methods in Chemistry

Research Article

Compound-Specific Chlorine Isotope Analysis of Organochlorine Pesticides by Gas Chromatography-Negative Chemical Ionization Mass Spectrometry

Table 1

Main ions and fragments of eight organochlorine pesticides obtained from electron ionization (EI) and negative chemical ionization (NCI).


Compounds	EI	NCI

HCH (α, β, γ, δ)	[M-nHCl]⁺, [M-nCl]⁺	35 [Cl]⁻, 71 [HCl₂]⁻, 37 [Cl]⁻
DDT (o, p′-, p, p′-)	235 [(C₆H₄Cl)₂CH]⁺	35 [Cl]⁻, 71 [HCl₂]⁻, 37 [Cl]⁻
p, p′-DDE	318 [M]⁺, 246[M-2HCl]⁺	35 [Cl]⁻, 37 [Cl]⁻
p, p′-DDD	235 [(C₆H₄Cl)₂CH]⁺	35 [Cl]⁻, 71 [HCl₂]⁻, 37 [Cl]⁻

Note: M represents molecular ion; eight organochlorine pesticides: α-hexachlorocyclohexane (α-HCH), β-hexachlorocyclohexane (β-HCH), γ-hexachlorocyclohexane (γ-HCH), δ-hexachlorocyclohexane (δ-HCH), 1-chloro-2-[2, 2, 2-trichloro-1-(4-chlorophenyl) ethyl] benzol (o, p′-DDT), 2, 2-bis (p-chlorophenyl)-1, 1, 1-trichloroethane (p, p′-DDT), 2, 2-dichloro-1, 1-bis (4-chlorophenyl) ethylene (p, p′-DDE), and 1, 1-dichloro-2, 2-bis (p-chlorophenyl) ethane (p, p′-DDD).