title: Zone fluidics for measurement of octanol-water partition coefficient of drugs.
abstract: A novel zone fluidics (ZF) system for the determination of the octanol-water partition coefficient (Pow) of drugs was developed. The ZF system consisted of a syringe pump with a selection valve, a holding column, a silica capillary flow-cell and an in-line spectrophotometer. Exact microliter volumes of solvents (octanol and phosphate buffer saline) and a solution of the drug, sandwiched between air segments, were sequentially loaded into the vertically aligned holding column. Distribution of the drug between the aqueous and octanol phases occurred by the oscillation movement of the syringe pump piston. Phase separation occurred due to the difference in densities. The liquid zones were then pushed into the detection flow cell. In this method, absorbance measurements in only one of the phase (octanol or aqueous) were employed, which together with the volumes of the solvents and pure drug sample, allowed the calculation of the Pow. The developed system was applied to the determination of the Pow of some common drugs. The log (Pow) values agreed well with a batch method (R(2)=0.999) and literature (R(2)=0.997). Standard deviations for intra- and inter-day analyses were both less than 0.1log unit. This ZF system provides a robust and automated method for screening of Pow values in the drug discovery process.
authors: Flow Innovation-Research for Science and Technology Laboratories (FIRST labs.), Thailand; Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors: Panwadee
authors: P
authors: Wattanasin
authors: Flow Innovation-Research for Science and Technology Laboratories (FIRST labs.), Thailand; Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors: Phoonthawee
authors: P
authors: Saetear
authors: Flow Innovation-Research for Science and Technology Laboratories (FIRST labs.), Thailand; Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand; National Doping Control Centre, Mahidol University, Bangkok 10400, Thailand.
authors: Prapin
authors: P
authors: Wilairat
authors: Flow Innovation-Research for Science and Technology Laboratories (FIRST labs.), Thailand; Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand. Electronic address: duangjai.nac@mahidol.ac.th.
authors: Duangjai
authors: D
authors: Nacapricha
authors: Flow Innovation-Research for Science and Technology Laboratories (FIRST labs.), Thailand; Department of Chemistry and Applied Analytical Chemistry Research Unit, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand. Electronic address: saowapak_teerasong@hotmail.com.
authors: Saowapak
authors: S
authors: Teerasong
mesh_terms: D020003:1-Octanol / Q000032:analysis*; D000082:Acetaminophen / Q000737:chemistry; D000814:Aniline Compounds / Q000737:chemistry; D002110:Caffeine / Q000737:chemistry; D004867:Equipment Design; D007052:Ibuprofen / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry; D012256:Riboflavin / Q000737:chemistry; D014867:Water / Q000032:analysis*
chemical_list: D000814:Aniline Compounds; D007093:Imidazoles; D014867:Water; D000082:Acetaminophen; D002110:Caffeine; C029899:imidazole; D020003:1-Octanol; C023650:aniline; D012256:Riboflavin; D007052:Ibuprofen
keywords: Drug discovery; Octanol–water partition coefficient; Zone fluidics