1. Academic Validation
  2. On accuracy and precision of a HPLC method for measurement of urine porphyrin concentrations

On accuracy and precision of a HPLC method for measurement of urine porphyrin concentrations

  • Clin Chem Lab Med. 2000 Mar;38(3):227-30. doi: 10.1515/CCLM.2000.033.
F M Zuijderhoudt 1 S G Koehorst W E Kluitenberg J Dorresteijn-de Bok
Affiliations

Affiliation

  • 1 Department of Clinical Chemistry, Deventer Ziekenhuis, The Netherlands.
Abstract

We studied the accuracy and precision of a HPLC method for determination of porphyrins in urine. A commercial standard solution appeared to contain less porphyrins than indicated by the manufacturer, since calibration resulted in lower concentrations of uroporphyrin and coproporphyrin: 16% and 8%, respectively. Coefficients of variation for the measurement of uro-, hepta-, copro I and copro III porphyrins in samples of patients with and without porphyria were often much less than 15%. Comparison of measurements with and without calibrated standards revealed differences for uroporphyrin and coproporphyrin of 27% and 5%, respectively. Recovery of added uroporphyrin and coproporphyrin was 99%. The main cause of the variability in test results was apparently the improperly calibrated standard solutions. The precision of porphyrin measurements was not influenced by the type of porphyria.

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