Vitamin C in Plasma

Ascorbic acid (1) in plasma. Plasma concentration is 41 μmol/l. Other peaks are: Urate (2), Hydrochinon (IS, 3) and DTT (4)..

Vitamin C in Plasma

• Standardized, fast and reliable assay
• Robust & reproducible

Ascorbic acid (AA) is normally present in human as well as in animal plasma and tissue. The daily need is considered to be at least 70 mg and normal blood levels are between 28 and 85 μM. For example, the analysis of AA in plasma of geriatric patients reflects the quality of feeding status of such patients.

Since it is quite labile, accurate measurement of AA in biological matrices highly depends on a reliable method to stabilise AA (1, 2). Dithiothreitol (DTT) and metaphosphoric acid (MPA) are quite effective as an aid for long-term stabilisation (up to one year) of AA in biological samples and, in addition, DTT appears to reduce dehydro-ascorbic acid.

The analysis with LCEC is very straightforward and highly reproducible with the use of hydrochinon as internal standard.

System configuration

For the analysis of vitamins we selected the VT03 electrochemical cell. This cell has an excellent reproducibility and the best possible detection sensitivity. The ALEXYS system comprises the following parts:

• AS 110 autosampler, cool
• LC 110S HPLC pump
• DECADE II electrochemical detector, SCC
• VT03 cell with 3 mm ID, HyREF
• OR 110 organiser rack
• LC connection kit
• USB connection kit, 3 port
• Clarity data acquisition software

Vitamin K requires an additional Reactor cell with a DECADE DCC for pre-reduction of the quinone moiety. For more details see our product catalogue.