I Would like to calculate the moisture content on pharmaceutical powder starting from NIR spectra. I didn't know the calibration curve. There is a way to understand only looking the spectra is the water content changes during the wet granulation? Could be possible to estimate the moisture? There is some kind of Mathematical formula?
Using a micropipette , put a drop of water (1...5 μL) on your sample and record again your spectra. For a lower content you may dilute water in acetone.
I suppose you work in reflectance mode. A linear variation is possible for log(1/R) vs. C.
An other option is a Karl Fisher titration of moisture content (difficult method for a beginner !).
Thank you for the Answer!. Unfortunately i received the NIR data acquired during the granulation without any other information regarding the water added or other method for the calculation of the moisture (calibration). The only information i have is the starting and finishing time of the different phases of the granulation: Mixing of the powder - input water - massing and drying. Without to know any other information how it is possible to calculate the moisture or the water content of the powder? can i fix my attention on a possible peak on the NIR spectra?
Read this
http://pubs.rsc.org/en/content/articlehtml/2014/cs/c4cs00062e
or similar.
Thank you for the article, really explanatory! We are also using Hyperspectral system but we didn't use it for moisture measurements. Our actual applications are focused on in-line mix-up detection between tablets.
In a word, no, you can't use any NIR band for quantitative measurements without either testing a sample series by NIR and a reference technique, or by using a standard addition method to establish a multi-frequency reference curve on a substantial quantity of (preferably initially anhydrous) sample. There are many techniques for measuring water -- if you have a KF apparatus, perhaps with an evaporator oven, that is good; there are also GC derivatization methods and azeotropic distillation methods which are more labor intensive.
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