title: Determination of n-octanol/water partition coefficient for DDT-related compounds by RP-HPLC with a novel dual-point retention time correction.
abstract: n-Octanol/water partition coefficients (P) for DDTs and dicofol were determined by reversed-phase high performance liquid chromatography (RP-HPLC) on a C(18) column using methanol-water mixture as mobile phase. A dual-point retention time correction (DP-RTC) was proposed to rectify chromatographic retention time (t(R)) shift resulted from stationary phase aging. Based on this correction, the relationship between logP and logk(w), the logarithm of the retention factor extrapolated to pure water, was investigated for a set of 12 benzene homologues and DDT-related compounds with reliable experimental P as model compounds. A linear regression logP=(1.10±0.04) logk(w) - (0.60±0.17) was established with correlation coefficient R(2) of 0.988, cross-validated correlation coefficient R(cv)(2) of 0.983 and standard deviation (SD) of 0.156. This model was further validated using four verification compounds, naphthalene, biphenyl, 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (p,p'-DDD) and 2,2-bis(4-chlorophenyl)-1,1-dichloroethene (p,p'-DDE) with similar structure to DDT. The RP-HPLC-determined P values showed good consistency with shake-flask (SFM) or slow-stirring (SSM) results, especially for highly hydrophobic compounds with logP in the range of 4-7. Then, the P values for five DDT-related compounds, 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1,1-trichloroethane (o,p'-DDT), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethane (o,p'-DDD), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethene (o,p'-DDE), and 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol) and its main degradation product 4,4'-dichlorobenzophenone (p,p'-DBP) were evaluated by the improved RP-HPLC method for the first time. The excellent precision with SD less than 0.03 proved that the novel DP-RTC protocol can significantly increases the determination accuracy and reliability of P by RP-HPLC.
authors.affiliation: Key Laboratory of Analytical Chemistry for Life Science (Ministry of Education of China), School of Chemistry & Chemical Engineering and Center of Materials Analysis, Nanjing University, 22 Hankou Road, Nanjing, China.
authors.forename: Shu-ying
authors.initials: SY
authors.lastname: Han
authors.forename: Jun-qin
authors.initials: JQ
authors.lastname: Qiao
authors.forename: Yun-yang
authors.initials: YY
authors.lastname: Zhang
authors.forename: Li-li
authors.initials: LL
authors.lastname: Yang
authors.forename: Hong-zhen
authors.initials: HZ
authors.lastname: Lian
authors.forename: Xin
authors.initials: X
authors.lastname: Ge
authors.forename: Hong-yuan
authors.initials: HY
authors.lastname: Chen
mesh_terms: D020003:1-Octanol / Q000032:analysis* / Q000737:chemistry / Q000592:standards; D002851:Chromatography, High Pressure Liquid; D003634:DDT / Q000032:analysis* / Q000737:chemistry / Q000592:standards; D003633:Dichlorodiphenyl Dichloroethylene / Q000032:analysis / Q000737:chemistry / Q000592:standards; D003632:Dichlorodiphenyldichloroethane / Q000032:analysis / Q000737:chemistry / Q000592:standards; D004010:Dicofol / Q000032:analysis / Q000737:chemistry / Q000592:standards; D004784:Environmental Monitoring / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry / Q000592:standards
chemical_list: D014874:Water Pollutants, Chemical; D003633:Dichlorodiphenyl Dichloroethylene; D003634:DDT; D020003:1-Octanol; D003632:Dichlorodiphenyldichloroethane; D004010:Dicofol