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- Posts: 11
- Joined: Tue Feb 25, 2020 3:03 am
DR wrote:
If the UV spectra for the additives you're looking for have any distinct local maxima, you might be able to ditch HPLC in favor of a UV/Vis method instead.
Lots less maintenance, less time checking samples, far fewer chemicals to buy... whether this would work is a function of whether the other mixture components absorb too strongly at a given wavelength.
I spent a decent amount of time yesterday running UV/Vis scans on three concentrations of the additive; 0.5%, 1.0%, and 3.0%bv. I ran multiple modes with rather poor results. Using absorbance, the three peak at slightly different wavelengths; 295, 297, and 301nm respectively. When comparing the absorbance ratios at their peaks, they are nowhere near the ratio of conc., and of course less accurate if selecting 297nm as that maximizes the 1.0% sample, but then hits off-peak on the other two. I did not bother integrating the areas since the peaks do not coincide.
UV/Vis is a Thermo Genesys10s using the VisionLite software.