The stability of retinol, α-tocopherol, trans-lycopene, and trans-β-carotene in liquid-frozen and lyophilized serum

Abstract

The concentrations of retinol, α-tocopherol, and trans-β-carotene in lyophilized serum stored at −25°C and −80°C have been monitored for 10 years. There was no evidence of degradation of any of these compounds over the 10-year period. Retinol, α-tocopherol, and trans-β-carotene were less stable at −25°C in liquid-frozen serum than they were in lyophilized serum. At −80°C, trans-β-carotene levels were stable for up to 3 years of storage in liquid-frozen serum. Both retinol and α-tocopherol appeared stable in liquid-frozen serum for at least 5 years at −80°C. The effect of repeated freeze/thaw cycles on retinol, α-tocopherol, trans-lycopene, and trans-β-carotene in liquid-frozen and reconstituted lyophilized serum both stored at −20°C was also studied. Retinol, α-tocopherol, trans-lycopene, and trans-β-carotene in reconstituted lyophilized serum stored at −20°C were stable for at least 3 days with minimal (<5) freeze/thaw cycles.