title: Comparative analysis of EPA and DHA in fish oil nutritional capsules by GC-MS.
abstract: BACKGROUND
  Fish oil is a popular nutritional product consumed in Hong Kong. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the two main bioactive components responsible for the health benefits of fish oil. Market survey in Hong Kong demonstrated that various fish oil capsules with different origins and prices are sold simultaneously. However, these capsules are labelled with same ingredient levels, namely EPA 180 mg/g and DHA 120 mg/g. This situation makes the consumers very confused. To evaluate the quality of various fish oil capsules, a comparative analysis of the contents of EPA and DHA in fish oil is crucial.
  
  
  METHODS
  A gas chromatography-mass spectrometry (GC-MS) method was developed for identification and determination of EPA and DHA in fish oil capsules. A comprehensive validation of the developed method was conducted. Ten batches of fish oil capsules samples purchased from drugstores of Hong Kong were analyzed by using the developed method.
  
  
  RESULTS
  The present method presented good sensitivity, precision and accuracy. The limits of detection (LOD) for EPA and DHA were 0.08 ng and 0.21 ng, respectively. The relative standard deviation (RSD) values of EPA and DHA for repeatability tests were both less than 1.05%; and the recovery for accuracy test of EPA and DHA were 100.50% and 103.83%, respectively. In ten fish oil samples, the contents of EPA ranged from 39.52 mg/g to 509.16 mg/g, and the contents of DHA ranged from 35.14 mg/g to 645.70 mg/g.
  
  
  CONCLUSIONS
  The present method is suitable for the quantitative analysis of EPA and DHA in fish oil capsules. There is a significant variation in the contents of the quantified components in fish oil samples, and there is not a linear relationship between price and contents of EPA and DHA. Strict supervision of the labelling of the fish oil capsules is urgently needed.
authors.affiliation: School of Chinese Medicine, Hong Kong Baptist University, Hong Kong Special Administrative Region, Hong Kong, China. yitao@hkbu.edu.hk.
authors.forename: Tao
authors.initials: T
authors.lastname: Yi
authors.forename: Shuk-Man
authors.initials: SM
authors.lastname: Li
authors.forename: Jia-Yi
authors.initials: JY
authors.lastname: Fan
authors.forename: Lan-Lan
authors.initials: LL
authors.lastname: Fan
authors.forename: Zhi-Feng
authors.initials: ZF
authors.lastname: Zhang
authors.forename: Pei
authors.initials: P
authors.lastname: Luo
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Zhang
authors.forename: Jian-Gang
authors.initials: JG
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Zhu
authors.forename: Zhong-Zhen
authors.initials: ZZ
authors.lastname: Zhao
authors.forename: Hu-Biao
authors.initials: HB
authors.lastname: Chen
mesh_terms: D000818:Animals; D002214:Capsules; D019587:Dietary Supplements / Q000032:analysis*; D004281:Docosahexaenoic Acids / Q000032:analysis*; D015118:Eicosapentaenoic Acid / Q000032:analysis*; D005395:Fish Oils / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans
chemical_list: D002214:Capsules; D005395:Fish Oils; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid