I am working to find incompatibility or precipitation point at different concentrations of ethanol from 10% to 50% with 4% IV bag Trisodium citrate. I am looking to find turbidity i.e Absorbance >/=0.015au. My questions are -
1) Prior to calibration, i blank my instrument with DI-water? (Is it right)
2) During calibration, i dilute trisodium citrate to 400,800,1600,2400 microgram/ml concentrations with water
3) Wavelength i use is 546nm. Am i right or wrong? In this wavelength De-ionized water (Blank) gives 0 absorbance.
4) During my measurement of samples, i change the configuration to fixed wavelengths mode and should i blank each time with a combination of ethanol and water prior to measuring my samples containing varying concentrations of ethanol and TSC.
5) I am getting negative absorbance values. How do i fix it?
Any help would be highly appreciated
Dear Megha,
For measuring precisely low absorbance values (such as those for your turbidity measurements), it is very important to zero the absorbance before each measurement with the pure (mixed) solvent. The reflection losses change significantly as ethanol is added to water and that probably changes the effective absorbance measured much more than the turbidity effect you are looking for. So I suggest that, for each citrate and ethanol concentration, you subtract the absorbance measured with and without citrate, to give the correct turbidity effect due to the solute.
Good luck!
Paulo
Thank You Paulo. Appreciate it. I hope blanking reaching time prior to sample measurement with pure solvent should help.
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