Development and validation of 14 human serum protein assays on the Roche cobas® c 501

J Clin Lab Anal. 2011;25(1):52-60. doi: 10.1002/jcla.20430.


Many laboratories rely on dedicated nephelometers and turbidimeters for the measurement of serum proteins. There are, however, a number of chemistry analyzers that offer open channel configurations for end-user applications. We developed and validated 14 human serum protein assays (α(1)-antitrypsin, α(2)-macroglobulin, albumin, apolipoproteins AI and B, complement components 3 and 4, haptoglobin, immunoglobulins A, G, and M, orosomucoid, transferrin, and transthyretin) on the Roche cobas(®) c 501. We obtained excellent precision at low, normal, and high physiologic concentrations of each protein (within-run imprecision CVs ≤2.5%, total imprecision CVs ≤3.6%). Linearity for each method was within 5% of the expected value throughout the calibration range, and method comparison studies to commercial assays from Roche or Siemens were in good agreement (r>0.975). We observed no significant interference from bilirubin (up to 414 mg/l), hemoglobin (up to 8.9 g/l), triglyceride (up to 28 g/l), or rheumatoid factor (up to 3,930 IU/ml). Calibration was stable for at least 14 days. The instrument's small reaction cell allowed us to conserve nearly 60% of our specimen and reagent volume compared with our previous system. These newly developed assays provide precise and accurate results with high throughput, but without the associated cost of a dedicated instrument.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Automation, Laboratory
  • Blood Proteins / analysis*
  • Calibration
  • Humans
  • Immunoassay / instrumentation
  • Immunoassay / methods*
  • Limit of Detection
  • Microchemistry / instrumentation
  • Microchemistry / methods
  • Nephelometry and Turbidimetry / instrumentation
  • Nephelometry and Turbidimetry / methods*
  • Reproducibility of Results
  • Time Factors


  • Blood Proteins