title: [Study on laboratory analysis and its variety for calcium in prepackaged foods].
abstract: OBJECTIVE
  To observe the variety of calcium analysis of prepackaged foods from different labs of China.
  
  
  METHODS
  Fourteen prepackaged foods from seven kinds were selected as food samples including cereal products, bean products, meat products, dairy products, beverages, nuts, snacks, according to national prepackaged foods consumption survey results in 2000. The calcium of samples were parallelly analyzed for three times by national standard methods in seven labs from all the country.
  
  
  RESULTS
  The 78.6% of results were up to grade by Grubbs, Cochran and Dixon screening methods. The accuracy of protein analysis was expressed by variety co efficiency (C.V%). The C.V% of inner labs and inter labs were from 2.21% to 8.13% and from 5.51% to 31.12%, the total and average C.V% level were 5.93%-31.24% and 22.10%. Besides fish tin (with low calcium content), the relative expanded uncertainty of protein detection was from 10.36% to 57.10% (average 39.78%).
  
  
  CONCLUSIONS
  Calcium analysis level in labs from all the country was fit for national standards, the most of variety and uncertainty of analysis was less than 60%.
authors.affiliation: Institute of Nutrition and Food Safety, Chinese Center for Disease Control and Prevention, Beijing 100050, China. hemei2003@163.com
authors.forename: Mei
authors.initials: M
authors.lastname: He
authors.forename: Jianhua
authors.initials: J
authors.lastname: Men
authors.forename: Thonggang
authors.initials: T
authors.lastname: Zhao
authors.forename: Guoquan
authors.initials: G
authors.lastname: Cui
mesh_terms: D002118:Calcium / Q000032:analysis*; D002523:Edible Grain / Q000737:chemistry; D005504:Food Analysis / Q000592:standards*; D005515:Food Labeling / Q000592:standards*; D018857:Food Packaging; D008461:Meat Products / Q000032:analysis; D009754:Nuts / Q000737:chemistry
chemical_list: D002118:Calcium