Is there any instrumental technique to find the number of water molecules present in an unknown compound?
karl fischer can give you an indication but you can do many things like:
1. LOD heating your sample at 105 celsius degree and measure the difference of weight
2. you can use TGA/DSC instrument and measure loss of weight between 100-105 C
but do OVI test by GC before for your sample to check if other organic solvents exist or not , if any other solvent detect you should neglect it from your weight of loss that calculated by LOD or TGA
...you can use NMR...if you have one. This actually is rather straighforward and non-disruptive....
NMR is the best choice..
IR can give you some idea, tho' i doubt it can quantify..
@thanks 2 all.............................
In my sense by using KF reagent we can determine % of water content as w/w but not number of water molecules......................................
TGA is possible, but you have to be sure, that you have no other fleeting molecules in your UNKNOWN compound. Coupled with IR or MS you will get an exact answer. At the same time you will get with TGA/DSC very good hints, about the rest of your compound. 105 °C and also KARL FISCHER TITRATION is only for free water useful (if you can solve your sample in waterless methanol). Maybe the heating up to 105 °C is not enough. If you have hydrated compounds, there can exist water in this compound much above this temperature (depending on the substances).
(It is all depending on what you want exactly)
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