title: Characterizing the variation in pH measurements with apheresis platelets.
abstract: BACKGROUND
  pH measurements of platelet (PLT) components remain a key parameter when assessing how storage and shipping conditions influence the retention of PLT properties. Studies were conducted to characterize variations in pH measured with two pH meters and a blood gas analyzer.
  
  
  METHODS
  Samples were obtained from apheresis PLT units that were stored with or without continuous agitation to measure a range of pH values. pH values were determined with pH meters at room temperature (20-24°C) upon placing of samples in 5-mL sterile polypropylene tubes and with the blood gas analyzer at 37°C upon injection of identical samples, with conversion to 22°C.
  
  
  RESULTS
  The calculated coefficient of variation (%CV) of pH measurements using pH meters (n = 10) was 0.43% or less. The %CV values were comparable with different samples having pH values ranging from 6.0 to 7.4. The %CV levels with the blood gas analyzer were comparable to those observed with the pH meters. The difference in the mean pH values for the two pH meters was no greater than 0.10 units, with 9 of 10 samples having differences in values of 0.05 or less; however, greater differences of values (0.1 to 0.2) were observed between pH measured using the blood gas analyzer and pH meters.
  
  
  CONCLUSIONS
  Our data show good precision and comparability of pH measurements with two pH meters. Differences in pH values were greater on comparison of the blood gas analyzer with the pH meters.
authors.affiliation: American Red Cross Biomedical Services, Holland Laboratory, Rockville, Maryland 20855, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Moroff
authors.forename: Shalini
authors.initials: S
authors.lastname: Seetharaman
authors.forename: James
authors.initials: J
authors.lastname: Kurtz
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wagner
mesh_terms: D001784:Blood Gas Analysis; D001792:Blood Platelets / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010983:Plateletpheresis; D012044:Regression Analysis; D013696:Temperature