title: The Kjeldahl method as a primary reference procedure for total protein in certified reference materials used in clinical chemistry. I. A review of Kjeldahl methods adopted by laboratory medicine.
abstract: We found previously that albumin-calibrated total protein in certified reference materials causes unacceptable positive bias in analysis of human sera. The simplest way to cure this defect is the use of human-based serum/plasma standards calibrated by the Kjeldahl method. Such standards, commutative with serum samples, will compensate for bias caused by lipids and bilirubin in most human sera. To find a suitable primary reference procedure for total protein in reference materials, we reviewed Kjeldahl methods adopted by laboratory medicine. We found two methods recommended for total protein in human samples: an indirect analysis based on total Kjeldahl nitrogen corrected for its nonprotein nitrogen and a direct analysis made on isolated protein precipitates. The methods found will be assessed in a subsequent article.
authors.affiliation: a Department of Chemistry, Faculty of Science , Masaryk University , Brno , Czech Republic.
authors.forename: Vratislav
authors.initials: V
authors.lastname: Chromý
authors.forename: Bára
authors.initials: B
authors.lastname: Vinklárková
authors.forename: Luděk
authors.initials: L
authors.lastname: Šprongl
authors.forename: Miroslava
authors.initials: M
authors.lastname: Bittová
mesh_terms: D002138:Calibration; D002624:Chemistry, Clinical / Q000379:methods*; D006801:Humans; D007753:Laboratories; D008511:Medicine; D011506:Proteins / Q000737:chemistry*; D012016:Reference Values
chemical_list: D011506:Proteins
keywords: Kjeldahl methods; calibration; clinical chemistry; reference materials; total protein