title: The use of Lenticules for the process control of enumeration techniques in food and environmental microbiology.
abstract: OBJECTIVE
  Lenticules consist of control-dried plano convex discs in which biologically-active materials are contained within a water-soluble matrix. They can be produced to contain stable numbers of bacteria from 10 cfu lenticule-1 to 108 cfu lenticule-1 with a wide variety of organisms. These experiments were carried out to validate their use as a tool for internal quality control in quantitative microbiology.
  
  
  RESULTS
  The Lenticules were used routinely in standard quantitative microbiological procedures across five laboratories. Results showed the materials to be stable, homogeneous and capable of identifying systematic errors.
  
  
  CONCLUSIONS
  The Lenticules provide suitable, stable control materials.
  
  
  CONCLUSIONS
  Routine internal quality control of quantitative measurements is greatly improved; the materials are easy to use and enable comparisons between laboratories to be made.
authors.affiliation: Public Health Laboratory Service North, Newcastle upon Tyne, UK.
authors.forename: N F
authors.initials: NF
authors.lastname: Lightfoot
authors.forename: I R
authors.initials: IR
authors.lastname: Richardson
authors.forename: J P
authors.initials: JP
authors.lastname: Harford
mesh_terms: D001419:Bacteria / Q000254:growth & development*; D001431:Bacteriological Techniques; D015169:Colony Count, Microbial / Q000295:instrumentation* / Q000379:methods*; D005374:Filtration / Q000379:methods; D005516:Food Microbiology / Q000592:standards*; D008567:Membranes, Artificial; D011786:Quality Control; D015203:Reproducibility of Results; D014871:Water Microbiology / Q000592:standards*
chemical_list: D008567:Membranes, Artificial