Aliquots were stored either in clear autosampler vials or amber glass autosampler vials to investigate the effect of photodegradation on vitamins. Experiments were run in triplicate and average peak area (��RSD) was considered in calculations.Results indicate that there is no statistically significant difference between standard solutions stored at ?20��C and ?80��C at every selleck chem time point (Student's t-test not significant, P > 0.05); there is no statistically significant difference between standards kept at room temperature and +4��C on the same day of preparation up to 14 days (P > 0.05), whereas a statistical significant difference can be observed after 30 days (P < 0.05; exact P = 0.029). There is a statistical significant difference between standards kept at +4��C and ?20��C after 30 days (P < 0.
05; exact P = 0.031) but no difference was noted between standards analysed on the same day of preparation, and after 7 and 14 days (P > 0.05). Photodegradation has a compound libraries significant impact upon vitamins break down: in fact, a statistically significant difference was noted between standards prepared in clear and amber glass autosampler vials soon after 7 days when kept at room temperature (P < 0.05; exact P = 0.017) and at +4��C (P < 0.05; exact P = 0.020); this difference increases over time, up to 30 days when the difference becomes statistically significant beyond 1% (P < 0.01; exact P = 0.0006). Ascorbic acid (vitamin C) and cyanocobalamin (B12) are the most sensitive to photodegradation.
Additionally, concentrations of vitamins were stable in processed (deproteinised) plasma samples and water-based controls for 24 hours when stored at +4��C prior to analysis [difference between peak area of vitamins in The insulin-like growth factor 1 (IGF-1) receptor standard samples and peak area of vitamins in processed samples did not reach statistical significance when stored at +4��C for 24 hours, Student's t-test not significant, P > 0.05].Three freeze-thaw cycles had an effect on the stability of vitamins (Student's t-test significant beyond 5%, exact P = 0.041). There is no statistically significant difference between freshly prepared, water-based standard solutions, and an aliquot of the same stored at ?20��C after one cycle of freeze-thaw (P > 0.05), but the difference in peak area reaches statistical significance after two freeze-thaw cycles (P < 0.05; exact P = 0.042).