How much Vitamin C is in these vitamins?
Vitamin C is a water soluble, key nutrient found in fruits, vegetables and berries. Unlike many animals, humans cannot synthesize their own vitamin C and must get it from their diets. One way to supplement the intake of vitamin C would be to take a vitamin. I decided to test 3 different vitamins for vitamin C, two tablets and one powder.
As with everything that we do at Lucidity we started with a suitable method.
| Lucidity LC-UV Conditions | |||
|---|---|---|---|
| Mobile Phase | 15 mM Potassium dihydrogen phosphate – pH 3.0 w/ phosphoric acid | ||
| Control | Isocratic | ||
| Flow | 1.0 mL/min | ||
| Sample Loop size | 5 μL | ||
| Column | C18 | 250 mm x 4.6 mm, 5.0 μm | |
| Wavelength | 245 ± 1 nm | ||
| Gradient Flow Program | |||
| %A | %B | Time | |
| 100 | 0 | 10 min | |
Up next a vitamin C standard was obtained from Sigma-Aldrich (p/n A92902) in the form of L-ascorbic acid. The standard was in powder form and needed to be put into solution. The diluent used was the mobile phase with 0.56 g of sodium EDTA added. Using the diluent and 126 mg of the L-ascorbic acid a stock standard was made, that stock was then diluted into three standards 0.30 mg/mL, 0.25 mg/mL and 0.20 mg/mL, all were diluted with the diluent.
The chromatogram of the 0.20 mg/mL standard
Calibration curve of the vitamin C standard
Overall the calibration was good with an R-squared value of 0.9925.
Next was to get the samples into solution. The two tablets were easy, one tablet each was put into a 50 mL centrifuge tube, for the powdered sample 514 mg of sample was added to a 50 mL centrifuge tube. The tubes were then placed into the Lucidity SimplePrep. The SimplePrep was programmed to add 35 mL of the diluent and agitate for 75 minutes at 35 °C. Once finished, the samples were then diluted to a final concentration of 0.250 mg/mL.
Chromatogram of vitamin C in Tablet A
Chromatogram of Vitamin C in Tablet B
Chromatogram of Vitamin C in the Powdered Sample
Once the samples are run, the Lucidity GC-FID software uses the calibration curve that was run earlier to calculate a concentration. Using the dilution factor for the tablets we get a percent recovery from Tablet A of 94.0%, and we get a percent recovery from Tablet B of 102.3%. For the powdered sample there was a serving size and a dilution factor to take into account. Using these, the percent recovery for the powdered sample is 95.3% recovery.