Evaluation of reactive oxygen metabolites in frozen serum samples. Effect of storage and repeated thawing

A. Cavalleri, C. Colombo, E. Venturelli, R. Miceli, L. Mariani, U. Cornelli, V. Pala, F. Berrino, G. Secreto

Research output: Contribution to journalArticlepeer-review


Measuring the free radical activity in serum samples from prospective studies is the best way to investigate the association between oxidative stress and human diseases. Prospective studies require the analysis of serum samples that have often been stored for a long time. Our study was designed to determine the effect of storage at -30°C and -80°C for two years on free radical activity. We analyzed the free radical activity by measuring circulating hydroperoxides in a pool of sera at baseline and after one day; one week, one month and 25 months of storage, using a photometric method (d-ROMs test). Measurements were performed in aliquots thawed only once at each time point and in aliquots frozen and thawed repeatedly over the study period. After two years we observed a small but statistically significant 4% decrease in the hydroperoxide concentration, which was substantially unaffected by storage temperatures and repeated freeze-thaw cycles. We also carried out the d-ROMs test in sera from ten apparently healthy volunteers at 2, 8, 24, and 48 hours after collection and storage at 40°C and did not observe any significant variation. In conclusion, the d-ROMs test is a simple method suitable to evaluate the free radical activity in frozen serum samples after long-term storage.

Original languageEnglish
Pages (from-to)250-253
Number of pages4
JournalInternational Journal of Biological Markers
Issue number3
Publication statusPublished - Jul 2004


  • d-ROMs test
  • Free radicals
  • Frozen serum
  • Oxidative stress
  • Serum storage

ASJC Scopus subject areas

  • Immunology
  • Biochemistry


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