title: Sample preparation for liquid chromatographic analysis of phytochemicals in biological fluids.
abstract: BACKGROUND
  Natural products have been used traditionally for the treatment and prevention of diseases for thousands of years and are nowadays consumed as dietary supplements and herbal medicine. To ensure the safe and effective use of these herbal products, information about bioavailability of active compounds in plasma or target tissues should be provided via validated analytical methods combined with appropriate sampling methods.
  
  
  OBJECTIVE
  To provide comprehensive and abridged information about sample preparation methods for the quantification of phytochemicals in biological samples using liquid chromatography analysis.
  
  
  METHODS
  Sample pre-treatment procedures used in analytical methods for in vivo pharmacokinetic studies of natural compounds or herbal medicines were reviewed. These were categorised according to the biological matrices (plasma, bile, urine, faeces and tissues) and sample clean-up processes (protein precipitation, liquid-liquid extraction and solid-phase extraction).
  
  
  RESULTS
  Although various kinds of sample pre-treatment methods have been developed, liquid-liquid extraction is still widely used and solid-phase extraction is becoming increasingly popular because of its efficiency for extensive clean up of complex matrix samples. However, protein precipitation is still favoured due to its simplicity.
  
  
  CONCLUSIONS
  Sample treatment for phytochemical analysis in biological fluids is an indispensable and critical step to obtain high quality results. This step could dominate the overall analytical process because both the duration of the process as well as the reliability of the data depend in large part on its efficiency. Thus, special attention should be given to the choice of a proper sample treatment method that targets analytes and their biomatrix.
authors.affiliation: College of Pharmacy, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Ju-Hee
authors.initials: JH
authors.lastname: Oh
authors.forename: Young-Joo
authors.initials: YJ
authors.lastname: Lee
mesh_terms: D001826:Body Fluids / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D064209:Phytochemicals / Q000032:analysis* / Q000097:blood / Q000652:urine; D052616:Solid Phase Extraction
chemical_list: D064209:Phytochemicals
keywords: Liquid-liquid extraction; natural compound; protein precipitation; sample pre-treatment; solid-phase extraction