title: Synchronous fluorescence determination of phytic acid in foodstuffs and urine based on replacement reaction.
abstract: BACKGROUND
  Phytic acid is a ubiquitous and abundant natural component in many plant seeds, fruits and vegetables. Its biological and pharmaceutical functions are still controversial. The examination on the level of phytic acid in foodstuffs and urine can provide valuable information for its dietary intake and metabolism.
  
  
  OBJECTIVE
  To develop a sensitive and reliable synchronous fluorescence protocol for determination of phytic acid in selected foodstuffs and human urine.
  
  
  METHODS
  Phytic acid efficiently catches Cu²+ ion in previously prepared Cu(II) -2,2'-bipyridine complex in aqueous solution, releasing the fluorescent 2,2'-bipyridine molecule and recovering synchronous fluorescence. The recovered fluorescence is proportional to the added phytic acid, by which the levels of phytic acid in the selected foodstuffs and human urine are quantified.
  
  
  RESULTS
  A calibration curve with a regression equation of I(f) = 37.745 + 39.245c (R² > 0.9988) showed good linearity over the range 0.18-17.50 mg/L phytic acid. The relative standard deviation at 95% confidence degree was less than 2.04% (n = 5), indicating that the procedures are reproducible. The detection and quantification limit of phytic acid were estimated to be 0.12 and 0.18 mg/L, respectively. By the proposed method, phytic acid in the selected foodstuffs and urine was determined to be 3.25-16.76 and 0.43-1.21 mg/L with recoveries of 96.8%-105.6% and 95.1%-104.2%, respectively. The results are in good agreement with those obtained by the reported HPLC technique.
  
  
  CONCLUSIONS
  The developed method is sensitive, reliable and economical, which permits its practical application in quantitative analyses of trace phytic acid in foodstuffs and urine.
authors.affiliation: School of Chemical and Biological Engineering, Yancheng Institute of Technology, Yancheng 224051, People's Republic of China.
authors.forename: Shuhong
authors.initials: S
authors.lastname: Cao
authors.forename: Nian
authors.initials: N
authors.lastname: Dong
authors.forename: Jingwen
authors.initials: J
authors.lastname: Chen
mesh_terms: D015082:2,2'-Dipyridyl / Q000032:analysis; D002138:Calibration; D003300:Copper / Q000737:chemistry; D005456:Fluorescent Dyes / Q000032:analysis; D005504:Food Analysis / Q000379:methods*; D006801:Humans; D007501:Iron / Q000737:chemistry; D008956:Models, Chemical; D010833:Phytic Acid / Q000032:analysis* / Q000737:chemistry / Q000652:urine*; D012044:Regression Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D015082:2,2'-Dipyridyl; D003300:Copper; D010833:Phytic Acid; D007501:Iron