What’s in my Gummies? Part 2
Continuing on from last week with the gummy bear sample preparations, I decided to take a look at the different things in that gummy bear. The gummy bear in question is a multivitamin that contains a multitude of different vitamins, so I decided to first focus on Vitamin C or Ascorbic Acid.
Preparing the sample was quite easy, as I used the Lucidity SimplePREP system. I used the gummy bear prep method from last week to do the sample prep for the sample agian this week. The method used is as follows:
| Lucidity SimplePREP Conditions | |||
|---|---|---|---|
| Temperature | 37 ℃ | ||
| Time | 60 minutes | ||
| Volume | 35 mL | ||
| Agitation | ON | ||
| Washes | 3 | ||
| Pretreat Volume | 0 mL | ||
| Filtering | OFF | ||
| Settling | 0 minutes | ||
Now, time to run the Ascorbic Acid standard to check the retention time. The LC-UV method used for the Ascorbic Acid is as follows:
| Lucidity LC-UV Method | |
|---|---|
| Flow Rate | 0.6 mL/min |
| Column | C18 150 x 4.6 mm, 2.7 um |
| Oven Temperature | 30 ℃ |
| Wavelength | 254 nm |
| Flow | Isocratic – 10 minutes |
| Mobile Phase | 1.58 g Sodium dihydrogen phosphate PH 3 |
Ascorbic Acid shows very well on the LC-UV detector and gives very nice sharp peaks.
Chromatogram of ascorbic acid at 25 ug/mL
I decided to make a standard curve using 2.5, 5 and 25 μg/mL giving an R² value of 0.9999. That is a great calibration curve, so I went on to the next step.
Calibration Curve for Vitamin C showing a good linear range and an R squared value of 0.9999
Moving on to the sample, I first calculated the dilution required to bring the sample into the range of the calibration curve using the labeled amount of Vitamin C as a guide. Using the labeled amount of Vitamin C (15 mg), I determined that 100:1 dilution would bring my sample into the range of the calibration curve (between injection concentrations of 2.5 ug/mL and 25 ug/mL).
I then filtered and diluted the sample 100:1 in water and ran it in the Lucidity LC-UV. The method produced a chromatogram with one peak, which it identified as Ascorbic Acid based on retention time and gave a concentration for Ascorbic Acid of 4.931 ug/mL based on the calibration curve associated with the method.
Chromatogram of the gummy sample diluted at 100 to 1
Taking into account the 100:1 dilution factor and the initial 35 mL of water that I added to the sample, the average amount per gummy for the samples is 15.4 mg. The labeled amount is 15 mg, giving me a 103% recovery on the sample, which is reasonably accurate.
Next week I plan to investigate how much Thiamine is in this same gummy. Stay tuned for these results.