Stability of Total Ascorbic Acid in DTT-Preserved Plasma Stored at 4°C
SU-CHEN LEE1,3, SHIH-MENG TSAI2, SHU-KAI LIN3, BAI-HSIUN CHEN1,3 AND LI-YU TSAI3,4*
1. Department of Laboratory Medicine, School of Medicine, Kaohsiung Medical University
2. Department of Public Health, School of Medicine, Kaohsiung Medical University
3. Department of Laboratory Medicine, Kaohsiung Medical University Hospital
4. School of Technology for Medical Sciences, Kaohsiung Medical University
1-4. 100 Shihcyuan lst Rd., Sanmin District, Kaohsiung City 807, Taiwan, R.O.C.
(Received: April 1, 2003; Accepted: May 4, 2004)
ABSTRACT
In order to evaluate the stability of total ascorbic acid (TAA) after storage in refrigeration at 4˚C, EDTA-blood was collected from 12 volunteers and preserved with dithiothreitol (DTT) immediately. After sampling, the blood was portioned into 19 micro-centrifuge tubes. One tube of sample was examined immediately by the capillary electrophoresis (CE) method, while the others were stored in refrigeration at 4˚C until analysis. TAA analysis were performed once every 4 hr for a total of 72 hr after the sample collection. Our results showed that TAA concentrations in these specimens did not alter significantly within the first 16 hr of storage; however, TAA levels started to decline significantly (p < 0.05) thereafter. These data demonstrated that DTT could be an effective preservative in maintaining the stability of TAA in a refrigerated temperature for up to 16 hr. Thus, it is advised that if the determination of TAA cannot be performed immediately, specimens must be preserved with DTT at the refrigerated temperature and assayed within 16 hr in order to prevent the occurrence of inaccurate results.
Key words: total ascorbic acid, dithiothreitol, capillary electrophoresis