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I work with a sugar product that contains saccharose (approx. 70 %), glucose syrup (approx. 15 %), glycerine (approx. 3 %) and some other ingedrients, e.g. water. Glucose syrup consists of 5 % glucose (Dx), 50 % maltose (Dp2), 25 % higher connected sugars (Dp3), 20 % water. I'd like to determine the amount of glucose syrup in the sample.

Fehling is time-consuming and well-known as an empirical method. Because the concentration of glucose, saccharose and maltose ist unknown (three variables and two equations: mass of cupperoxide before inversion and mass of cupperoxide after inversion) I think it's not possible to calculate accurate enough the amount of glucose syrup. The error should be lower than 5 % of the real value.

To measure the Brix-value in order to determine the glucose syrupe concentration is too inaccurate.

An alternative would be to use enzymatic test-kits which are selective for maltose. Unfortunately this test is too expensive and when opened it must be used within a few days or weeks.

My idea is to label a protecting group with an fluorescent group and to put it on the maltose molecule. The protecting group should only bind to the molecule, if the distance between two hydroxy-groups is given. enter image description here

(Unfortunately I don't know the distance between the two hydrox groups).

Which protecting group could be the solution of this problem?

Or do you know an even easier procedure to determine the glucose syrup amount?

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  • $\begingroup$ Do you have to perform the analysis periodically? Which instruments are available? Did you consider fluorescence labelling and HPLC? $\endgroup$ – Klaus-Dieter Warzecha Nov 28 '16 at 13:24
  • $\begingroup$ We could use a UV/VIS spectrometer (but we have no HPLC). We need to do the analysis one day per month or less, but we really like to do it in our laboratory. $\endgroup$ – user37991 Dec 2 '16 at 13:24

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