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

Table 2

Isotope ratios (IR (³⁷Cl/³⁵Cl)), standard deviations (1σ), and δ³⁷Cl′ for Supelco standards and O2si standards calculated in relation to external isotope standards from AccuStandard.

Compounds	AccuStandard (IR (^37Cl/^35Cl), 1σ)	Supelco (IR (^37Cl/^35Cl), 1σ)	O2si (IR (^37Cl/^35Cl), 1σ)	Supelco δ^37Cl′ (1σ, %)	O2si δ^37Cl′ (1σ, %)
α-HCH	0.30464 ± 0.00032	0.30551 ± 0.00059	0.30314 ± 0.00069	2.86 ± 1.94	−4.91 ± 2.26
β-HCH	0.31069 ± 0.00041	0.31081 ± 0.00093	0.31014 ± 0.00093	0.39 ± 2.99	−1.78 ± 2.98
γ-HCH	0.31014 ± 0.00075	0.31072 ± 0.00107	0.31150 ± 0.00158	1.89 ± 3.44	4.41 ± 5.08
δ-HCH	0.31050 ± 0.00073	0.31062 ± 0.00065	0.30876 ± 0.00084	0.40 ± 2.09	−5.59 ± 2.72
o, p′-DDT	0.31560 ± 0.00113	0.31473 ± 0.00129	0.31459 ± 0.00173	−2.78 ± 4.10	−3.22 ± 5.48
p, p′-DDT	0.30595 ± 0.00146	0.30273 ± 0.00182	0.30562 ± 0.00204	−10.55 ± 5.96	−1.09 ± 6.66
p, p′-DDE	0.29923 ± 0.00105	0.29672 ± 0.00060	0.30002 ± 0.00060	−8.37 ± 2.02	2.63 ± 2.00
p, p′-DDD	0.30860 ± 0.00106	0.30967 ± 0.00209	0.30749 ± 0.00140	3.49 ± 6.76	−3.60 ± 4.54

Note: results were acquired from five replicated injections. 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).