Analytical Method: Determination of Sugar Solution Color at pH 7.0 (According to ICUMSA Method GS2/3-9)

Materials and Reagents:
Cat.No. 1.16754.9010  Water for analysis EMSURE® or distilled water
Cat.No. 1.09060.1000  Hydrochloric acid  0.1 mol/l Titripur®
Cat.No. 1.08379.0250  Triethanolamine (TEA) for analysis

Cat.No. 1.14944.0001  Rectangular cells 50 mm or
Cat.No. 1.74011.0001  Rectangular cell 100 mm (Prove 600 only)

Cat.No. 1.73016.0001 Spectroquant® VIS Spectrophotometer Prove 100 or
Cat.No. 1.73017.0001 Spectroquant® UV/VIS Spectrophotometer Prove 300 or
Cat.No. 1.73018.0001 Spectroquant® UV/VIS Spectrophotometer Prove 600

Membrane filters, cellulose nitrate, pore size 0.45 µm, diameter 50 mm
Conical flasks 250 ml
Volumetric flask 500 ml
Beaker 1000 ml
pH meter
Ultrasonic bath

Spectrophotometric Color Determination at 420 nm

Measuring range:
Method No. 2549
0 – 600 IU7.0

Working instructions:
TEA buffer solution
Dissolve 7.46 g of TEA in 200 ml water (Water for analysis EMSURE® is recommended), transfer to a 500 ml volumetric flask and make up to the mark with water. Transfer the 500 ml to a beaker and adjust the solution to pH 7.0 with 0.1 mol/l Hydrochloric acid Titripur® (approx. 420 ml of hydrochloric acid solution are required).

Sample preparation
Mix the sample thoroughly.
Weigh 50.0 ± 0.1g of the sample into a 250 ml conical flask.
Add 50.0 ± 0.1g of the prepared TEA buffer solution and dissolve the sample by swirling at room temperature.
Vacuum-filter the pretreated solution over a membrane filter into a clean and dry conical flask.
Degas the solution for 3 minutes in the ultrasonic bath.

Measure the % RDS (refractometric dry substance) of the solution to an accuracy of ± 0.1 g/100g (according to ICUMSA Method GS4/3-13).

Zero adjustment
For each measurement series, a zero adjustment is required.
It is recommended to use the same cell for zero adjustment and for sample measurement.
The zeroing procedure for the measurement series is automatically prompted by the instrument after entering the %RDS value.
For zero adjustment fill a corresponding rectangular cell with TEA buffer solution.
After prompting, place the rectangular cell filled with buffer solution in the cell compartment, the zero adjustment is executed automatically.
Confirm the implementation of zero adjustment with OK.
The zero adjustment is valid for the entire measurement series.

Measurement procedure
Select the method (2549, "ICUMSA Color GS2/3-9") from the method list of the Spectroquant® Prove.
Enter the RDS value in %. Confirm with OK.
Press START to start the measurement mode.
Perform a zero adjustment (procedure see “Zero adjustment”) with TEA buffer solution.
Transfer the sample solution into a corresponding cell. Place the cell into the cell compartment. The measurement is performed automatically.
Confirm measurement with OK. The IU7.0 value is shown in the display.

Press START to start the measurement procedure for the next sample. The system does not prompt a repeat of the zero adjustment.

The result is calculated according to ICUMSA GS2/3-9(2005) chapter 8.1 and ICUMSA SPS-4 table B (Sucrose; 20°C).
Individual ICUMSA methods or references are available online within 48 h: under “Methods book”.

Short measuring procedures on Spectroquant® Prove instruments are described in the Analytical Procedures and Appendices, available online on our website.



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