10.2
First Aid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.1 FIRST AID CABINET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.2 TREATMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.2.1
EYE INJURIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.2.2
WOUNDS AND HAEMORRHAGE . . . . . . . . . . . . .
10.2.2.3
BURNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.2.4
SHOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.2.5
FAINTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.2.6
ELECTRIC SHOCK . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.2.7
ARTIFICIAL RESPIRATION . . . . . . . . . . . . . . . . .
10.2.2.8
CARDIAC MASSAGE . . . . . . . . . . . . . . . . . . . . . . .
10.2.2.9
POISONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
168
168
170
170
170
170
171
171
171
171
172
172
CHAPTER 7
SMRI Test Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
Affination of Raw Sugar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
Determination of the Refractometer Brix in Juice (First Expressed Juice, First Mill
Juice and Mixed Juice Etc.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Determination of the Brix in Molasses Using A Hydrometer (Double Dilution) . . 178
Determination of the Refractometer Brix of Molasses . . . . . . . . . . . . . . . . . . . . . . 180
Determination of the Refractometer Brix in Syrup . . . . . . . . . . . . . . . . . . . . . . . . . 182
The Caking of White Sugar by the Test Tube Method . . . . . . . . . . . . . . . . . . . . . . 184
Determination of the Conductivity Ash in Molasses . . . . . . . . . . . . . . . . . . . . . . . . 185
Determination of the Conductivity Ash in Raw Sugar . . . . . . . . . . . . . . . . . . . . . . 188
Determination of the Conductivity Ash in Syrup . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Determination of the Conductivity Ash in White Sugar . . . . . . . . . . . . . . . . . . . . . 194
Determination of the Filtration Index of White Sugar . . . . . . . . . . . . . . . . . . . . . . . 198
Determination of the Floc in White Sugars by the 10 Day Coca-cola Method . . . . 200
Determination of the Floc Potential of White Sugars Using the Alcian Blue Floc
Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Determination of the Gums (Total Polysaccharides) in Molasses . . . . . . . . . . . . . . 204
Determination of the Gums (Total Polysaccharides) in Raw Sugar . . . . . . . . . . . . 207
Determination of the Gums (Total Polysaccharides) in
Syrup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Determination of the Colour and Turbidity in Clear Juice . . . . . . . . . . . . . . . . . . . 214
Determination of the Colour in Mixed Juice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Determination of the Colour in Molasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
Determination of the Colour of Raw Sugar in Solution . . . . . . . . . . . . . . . . . . . . . 221
Determination of the Colour and Turbidity in Syrup . . . . . . . . . . . . . . . . . . . . . . . . 225
Determination of the Colour and Turbidity of White Sugar in Solution . . . . . . . . . 228
Determination of the Turbidity At 720 Nm of White Sugar in Solution . . . . . . . . . 233
Determination of the Insoluble Matter in Mixed Juice . . . . . . . . . . . . . . . . . . . . . . 234
Determination of the Insoluble Matter in Raw/golden Brown Sugar . . . . . . . . . . .
Determination of the Insoluble Matter in White Sugar by Membrane Filtration . . .
Determination of the Moisture in Final Molasses Using the Karl Fischer Titration
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Determination of the Moisture in White Sugar Using Karl Fischer Titration
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
237
240
243
247
Determination of the Odour in White Sugar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Determination of the Odour in White Sugar on
Acidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
Determination of the Foreign Taste in White Sugar . . . . . . . . . . . . . . . . . . . . . . . . 253
Determination of the Dry Substance and Moisture in Molasses by Vacuum Oven
Drying on Sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
Determination of the Moisture in Raw Sugar by Loss on Drying . . . . . . . . . . . . . . 257
Determination of the Moisture in White Sugar by Loss on Drying . . . . . . . . . . . . . 260
Determination of the Particle/grain Size Distribution of Raw Sugar . . . . . . . . . . . . 262
Determination of the Particle/grain Size Distribution of White Sugar by Sieving . 268
Determination of the Ph of Juice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Determination of the Inorganic and Total Phoshate in Raw Sugar . . . . . . . . . . . . . 274
Determination of the Polarisation (Pol) of Juice . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
Determination of the Polarisation (Pol) of Molasses . . . . . . . . . . . . . . . . . . . . . . . . 280
Determination of the Polarisation (Pol) of Raw Sugar . . . . . . . . . . . . . . . . . . . . . . 283
Determination of the Polarisation (Pol) of Syrup . . . . . . . . . . . . . . . . . . . . . . . . . . 288
Determination of the Polarisation (Pol) of White Sugar . . . . . . . . . . . . . . . . . . . . . 290
Determination of the Reducing Sugars in Juice by the Lane and Eynon Method . . 293
Determination of the Reducing Sugars in Molasses by the Lane and Eynon
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
Determination of the Sucrose in Molasses by the Lane and Eynon Method . . . . . . 301
Determination of the Reducing Sugars in Raw Sugar by the Luff Schoorl Method 306
Determination of the Reducing Sugars in White Sugar by the Knight and Allen
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
Determination of the Starch in Clear Juice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
Determination of the Starch in Molasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Determination of the Starch in Raw Sugar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
Determination of the Starch in Syrup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
Determination of the Sulphated Ash in Juice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Determination of the Sulphated Ash in Molasses . . . . . . . . . . . . . . . . . . . . . . . . . . 334
Determination of the Sulphated Ash in Raw Sugar . . . . . . . . . . . . . . . . . . . . . . . . . 337
Determination of the Sulphated Ash in Syrup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
Determination of the Sulphated Ash in White Sugar . . . . . . . . . . . . . . . . . . . . . . . . 342
Determination of the Sulphite in White Sugar by the Rosaniline Hydrochloric
Colorimetric Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
Determination of the Visual Appearance of White Sugar Using Braunschweig Colour
Type Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
Determination of the Floc in White Sugars by the 10 Day Low Brix Coca-cola
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
Determination of the Bacteriological Quality of Water by the Membrane Filter
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
Determination of the Chemical Oxygen Demand in Effluent by the Semi-micro
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
Determination of the Total Mesophilic Bacteria, Yeasts and Moulds in White Sugar
by the Membrane Filter Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
Determination of the Total Thermophilic Organisms, Flat Sour Spores, Anaerobic
Organisms Producing Sulphide and Anaerobic Organisms Producing Gas in Canners'
Sugar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
the Determination of Glucose, Fructose and Sucrose in Cane Mixed Juice and
Molasses by Gas Chromatography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370
the Determination of Glucose, Fructose and Sucrose in Cane Mixed Juice and
Molasses by High Performance Ion Chromatography (Dionex Detector) . . . . . . . . 377
CHAPTER 8
Reference Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384
Table 1:
Refractive indices of aqueous sucrose solutions versus brix at 20oC and
λ = 589 nm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385
Table 2:
International temperature correction table (1936) for the normal model
of refractometer, above and below 20 oC . . . . . . . . . . . . . . . . . . . . . 388
Table 3:
Schmitz’s table for pol in juice for use in the dry lead sub-acetate
method Normal mass of 26,000g . . . . . . . . . . . . . . . . . . . . . . . . . . . 389
Table 4:
Adjustments to be made to the brix measured at 20 oC for use with
Schmitz’s table when the saccharimeter reading is taken at a
temperature other than 20 oC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
Table 5:
Solubility of sucrose in water in g sucrose (S) per 100g solution
(Charles) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395
Table 6:
Temperature corrections to readings of brix hydrometers (calibrated at
20 oC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396
Table 7:
Milligrams of reducing sugars required to reduce 10 cm3 Fehling’s
solution (Eynon and Lane method) . . . . . . . . . . . . . . . . . . . . . . . . . 398
Table 8:
Brix, apparent density and grams of sucrose per 100 cm3 of sugar
solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
Table 9:
Conversions of cm3 of 0,1 M sodium thiosulphate into mg of reducing
sugar, when 2,0 or 5,0g of sucrose are present in the titrated volume
(for Luff-Schoorl method of analysis) . . . . . . . . . . . . . . . . . . . . . . . 409
Table 10:
Corrections to be applied to the iodine titre to obtain mg of invert sugar
by the Ofner method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
Table 11:
Mass per unit volume of sugar solutions at 20 oC for different brix
values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412
Table 12:
Volume of sucrose solutions at different temperatures . . . . . . . . . . 419
Table 13:
Most probable number table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420
Table 14:
Factory materials - a guide to frequency of sampling and analysis . 421
Table 15:
Specifications for South African sugars . . . . . . . . . . . . . . . . . . . . . . 424
Table 16:
Properties of saturated steam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425
Table 17:
Cellulose papers - Whatman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427
Table 18:
Factor 0,03936 Pc0,6, for corrected reduced extraction . . . . . . . . . . 428
Table 19:
Typical coal analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433
DETERMINATION OF THE COLOUR AND TURBIDITY IN CLEAR JUICE
1.
Scope and Field of Application
The measurement of colour and turbidity is usually made on clear juice and the result gives
a useful measure of the effectiveness of the clarification process.
2.
Principle
At 5 Brix solution is prepared. Half of the solution is filtered through a membrane filter.
The filtered and unfiltered solutions are both adjusted to pH = 7 ± 0,02 and the absorbances
read at 420 nm. The turbidity is measured indirectly by the subtraction of ICUMSA 420
colour from the absorbancy index of the unfiltered solution.
3.
Reagents
Use only analytical grade reagents unless otherwise specified.
3.1
Distilled water
3.2
Hydrochloric acid 1 M - Measure 98 cm3 concentrated hydrochloric acid and dilute to 1000
cm3 in a volumetric flask.
3.3
Hydrochloric acid 0,05 M - Pipette 10 cm3 of 1 M hydrochloric acid into a 200 cm3
volumetric flask and make to volume with distilled water.
3.4
Sodium hydroxide 1 M - Weigh 40,0 g sodium hydroxide pellets and dissolve in some
distilled water. Cool the solution and then dilute to 1000 cm3 in a volumetric flask.
3.5
Sodium hydroxide 0,05 M - Pipette 10 cm3 of 1 M sodium hydroxide into a 200 cm3
volumetric flask and make to volume with distilled water.
4.
Apparatus
4.1
Spectrphotometer - Capable of light transmission measurements at a wavelength of 420 nm
with the narrowest practical bandwidth, e.g. ± 10 mm.
4.2
Optical glass cells - 10 mm
4.3
pH meter - Calibrated to one point (Buffer 7)
4.4
Buchner flask - 500 cm3 + buchner funnel 60 mm φ
4.5
Beakers - 250 cm3, 100 cm3
4.6
Membrane filters - 0,45 µm pore size, 50 or 47 mm φ (Cellulose nitrate)
214
4.7
Bench refractometer
4.8
Top pan balance - Readable to 0,01 g
5.
Procedure
Determine the brix of the juice. Prepare a 5 brix solution of juice according to the
following:
mass of juice to be taken to give 5 Brix solution
=
100 x 5
Brix 1
Weigh this amount into a beaker and make up to 100 ± 0,02 g with distilled water and stir
well. Divide this solution into two 250 cm3 beakers. Filter one half through a membrane filter
under vacuum. Adjust the pH of both the filtered and unfiltered solutions to 7 ± 0,02. Read
the absorbance of these solutions in a 1 cm cell at 420 nm. Read the refractometer brix of
each solution.
6.
Expression of Results
ICUMSA 420 Colour of the filtered juice
where As
b
c
=
=
=
=
As x 10 000
bc
absorbance at 420 nm
cell length (mm)
concentration of total solids (g/cm3) [Refer Appendix A - Table 2].
Turbidity of the unfiltered juice is calculated as follows and used for in-house control only:
Turbidity @ 420 nm
=
[(Absorbancy index of unfiltered sample) x 1000] - ICUMSA
420 Colour
where absorbancy index of unfiltered sample
=
Aus x 10
bc
and
Aus
=
absorbance of unfiltered sample at 420 nm
b
=
cell length (mm)
c
=
concentration of total solids (g/cm3) [Refer Appendix A Table 2]
Report the ICUMSA 420 colour and turbidity values to the nearest 10 units.
EXAMPLE:
215
The brix of the prepared juice solution is 5 , therefore from Table 2 in Appendix A, the total
solids in g/cm3 is 0,051.
Absorbance As of filtered solution at 420 nm
=
0,529
Concentration of filtered solution
=
0,051 g/cm3
ICUMSA 420 colour of juice
=
0,529 x 10 000
5 x 0,051
20745
Concentration of the unfiltered solution
=
0,051 g/cm3
Absorbancy index of the unfiltered sample at 420 nm
=
0,742 x 10
5 x 0,051
=
29,10
=
(29,10 x 1000)- 20745
=
8355
Turbidity of juice t 420 nm
=
Report both colour and turbidity at 420 nm as 20750 and 8360 respectively.
7.
Bibliography
7.1
Laboratory Manual for South African Sugar Factories - 3rd Edition p 262.
216
DETERMINATION OF THE COLOUR IN MIXED JUICE
1.
Scope and Field of Application
This method is applicable for mixed juice only.
2.
Principle
A diluted sample of mixed juice passed through a membrane filter. The filtered solution is
adjusted to pH = 7 ± 0,02 and the absorbance and brix are read. The colour is then calculated.
3.
Reagents
Use analytical grade reagents unless otherwise specified.
3.1
Membrane filters - 0,45 µm pore size, 50 mm φ, 47 mm φ Cellulose nitrate.
3.2
Distilled water
3.3
Hydrochloric acid 1 M - Measure 98 cm3 concentrated hydrochloric acid and dilute to 1000
cm3 in a volumetric flask.
3.4
Hydrochloric acid 0,05 M - Pipette 10 cm3 of 1 M hydrochloric acid into a 200 cm3
volumetric flask and make to volume with distilled water.
3.5
Sodium hydroxide 1 M - Weigh 40,0 g sodium hydroxide pellets and dissolve in some
distilled water. Cool the solution and then dilute to 1000 cm3 in a volumetric flask.
3.6
Sodium hydroxide 0,05 M - Pipette 10 cm3 of 1 M sodium hydroxide into a 200 cm3
volumetric flask and make to the mark with distilled water.
4.
Apparatus
4.1
Spectrophotometer - Capable of light transmission measurements at a wavelength of 420 nm
with the narrowest practical bandwidth, e.g. ± 10 mm.
4.2
Optical glass cells - 10 mm
4.3
pH meter - Calibrated to one point (Buffer 7)
4.4
Buchner flask - 500 cm3 + Buchner funnel 60 mm φ
4.5
Beakers - 50 cm3, 250 cm3 and 100 cm3 with volume markings.
4.6
Bench refractometer
217
4.7
Magnetic stirrer - With follower
5.
Procedure
Mix the sample thoroughly. Prepare a 5 brix solution. For example if the brix of the juice
= 13,25 then to make 100 g of 5 brix solution:
Weigh
100 x
13,25
5
1
=
37,74 g juice
and make up to 100 g with distilled water and stir well. Filter through a membrane under
vacuum. Adjust the pH of this filtered solution to 7 ± 0,02 and read the absorbance on the
spectrophotometer using a 10 mm cell at 420 nm. Read brix of this solution and calculate
colour.
6.
Expression of Results
ICUMSA 420 colour of juice =
As x 10 000
bc
where As
b
c
=
=
=
absorbance at 420 nm
cell length (mm)
concentration of total solids (g/cm3) [Refer Appendix A - Table 2]
Report colour value to the nearest 10 units.
EXAMPLE:
The brix of the prepared juice solution is 5 , therefore from Table 2 in
Appendix A the total solids in g/cm3 is 0,051.
Absorbance of filtered solution at 420
=
0,529
Concentration of filtered solution
=
0,051 g/cm3
ICUMSA 420 colour of mixed juice
=
0,529 x 10 000
5 x 0,051
=
20745
Report to the nearest 10 units, i.e. 20750.
7.
Bibliography
7.1
Method taken from clear juice colour determination, Laboratory Manual for South African
Sugar Factories - 3rd Edition p 262.
218
DETERMINATION OF THE COLOUR IN MOLASSES
1.
Scope and Field of Application
This method is applicable to all molasses.
2.
Principle
The molasses sample is diluted and filtered through a membrane. The filtered solution is
adjusted to pH = 7 ± 0,02 and the absorbance is read on a spectrophotometer. The brix is read
and the colour is calculated.
3.
Reagents
Use analytical grade reagents unless otherwise specified.
3.1
Distilled water
3.2
Membrane filters - Cellulose nitrate 0,45 µm pore size, 50 mm/40 mm φ
3.3
Hydrochloric acid 1 M - Measure 98 cm3 concentrated hydrochloric acid and dilute to 1000
cm3 in a volumetric flask.
3.4
Hydrochloric acid 0,05 M - Pipette 10 cm3 of 1 M hydrochloride acid into 200 cm3
volumetric flask and make to the mark with distilled water.
3.5
Sodium hydroxide 1 M - Weigh 40,0 g sodium hydroxide pellets and dissolve in some
distilled water. Cool the solution and then dilute to 1000 cm3 in a volumetric flask.
3.6
Sodium hydroxide 0,05 M - Pipette 10 cm3 of 1 M sodium hydroxide into a 200 cm3
volumetric flask and make to the mark with distilled water.
4.
Apparatus
4.1
Spectrophotometer - Capable of light transmission measurements at a wavelength of 420 nm
with the narrowest practical bandwidth e.g. ± 10 mm.
4.2
Optical glass cells - 10 mm
4.3
pH Meter - Calibrated to one point (Buffer 7)
4.4
Buchner flask - 500 cm3 + Buchner funnel 60 mm φ and rubber bung to fit Buchner flask.
4.5
Beakers - 250 cm3 with volume markings.
4.6
Magnetic stirrer - With follower
219
4.7
Bench refractometer
5.
Procedure
Mix the molasses sample thoroughly. Pour ca. 25 cm3 into a 250 cm3 beaker, Dilute with
distilled water to about 200 cm3 and mix well using the stirrer bar. Filter this solution under
vacuum through a 0,45 µm membrane filter. Adjust the pH of this filtered solution to 7 ±
0,02 and read the absorbance in a 10 mm cell using the spectrophotometer at 420 nm [NB
= If the reading on the spectrophotometer is too high and/or is unstable, then a 50 mm cell
should be used]. Read the brix of the solution on the bench refractometer.
6.
Expression of Results
ICUMSA 420 Colour =
where As
b
c
=
=
=
As x 10 000
bc
absorbance of filtered solution
cell length (mm)
concentration of total solids (g/cm3) [Refer Appendix A - Table 2]
Report to the nearest 10 units.
EXAMPLE:
Brix of the filtered molasses solution is 2,78 and from Table 2 in Appendix A the
concentration of solids is 0,02826 g/cm3
Absorbance of filtered molasses solution
=
2,198
ICUMSA 420 colour of molasses
=
2,198 x 10 000 = 155 556
5 x 0,02826
Report colour values to the nearest 10 units, i.e. 155 560
7.
Bibliography
7.1
Method developed at SMRI.
220
DETERMINATION OF THE COLOUR OF RAW SUGAR IN SOLUTION
1.
Scope
This method is used for the determination of the colour of raw sugar in solution.
2.
Field of Application
The method can be applied to raw and affinated raw sugars provided that a filtered test
solution can be prepared by the procedure specified in the method.
3.
Definitions
3.1
Transmittance of a solution - If I1 represents the radiant energy incident upon the first surface
of the solution, and I2 represents the radiant energy leaving the second surface of the solution.
Then:
T = I2/I1
and
3.2
100T =
Tsoln/Tsolv
percentage transmittance
=
transmittancy of the solution
Absorbancy (extinction)
As = -log10Ts =
3.4
transmittance of the solution
Transmittancy - Let Tsoln represent the transmittance of a cell containing the solution and let
Tsolv represent the transmittance of the same or duplicate cell containing the pure solvent.
Then:
Ts =
3.3
=
absorbancy of the solution.
Absorbancy index (extinction index) - Let b represent the length (mm) of the absorbing path
between the boundary layers of the solution and let c represent the concentration (g/cm3) of
the sugar solution.
Then:
As
3.5.
=
As
bc
=
absorbancy index of the solution.
ICUMSA Colour - The value of the absorbancy index multiplied by 1000 is reported as
ICUMSA Colour and the resulting values are designated as ICUMSA Units (IU). Since,
however, the wavelength at which the determination of colour in solution is used is set at
420 nm, the value is designated as being the ICUMSA 420 Colour.
221
4.
Principle
Raw sugar is dissolved in distilled water, the solution is filtered through a membrane filter
to remove turbidity and the pH is adjusted to 7 ± 0,02. The absorbancy of the filtered solution
is measured at a wavelength of 420 nm and the colour of the solution is calculated.
5.
Reagents
Use only reagents of recognised analytical grade and only distilled water or water of
equivalent purity.
5.1
Hydrocloric acid 1 M - Measure 98 cm3 concentrated hydrochloric acid and dilute to 1000
cm3 in a volumetric flask.
5.2
Hydrochloric acid 0,05 M - Pipette 10 cm3 1 M hydrochloric acid into 200 cm3 volumetric
flask and make to the mark with distilled water.
5.3
Sodium hydroxide 1 M - Weigh 40,0 g sodium hydroxide pellets and dissolve in some
distilled water. Cool the solution and then dilute to 1000 cm3 in a volumetric flask.
5.4
Sodium hydroxide 0,05 M - Pipette 10 cm3 of 1 M sodium hydroxide into a 200 cm3
volumetric flask and make to the mark with distilled water.
6.
Apparatus
6.1
Spectrophotometer - Capable of light transmission measurements at a wavelength of 420 nm
with the narrowest practical band width, e.g. ± 10 nm.
6.2
Optical glass cells - 10 mm
6.3
Membrane filters - Cellulose nitrate filters with a pore size 0,45 µm and 50 mm/47 mm φ.
6.4
Buchner funnel - Porcelain - 50-65 mm φ
6.5
Buchner flask - 500 cm3 capacity with rubber bung to fit flask.
6.6
pH meter - Capable of measuring to 0,01 pH.
6.7
Refractometer
6.8
Magnetic stirrer - With follower
6.9
Laboratory balance - Readable to 0,01 g.
6.10
Beakers - 250 cm3, 100 or 50 cm3.
222
7.
Procedure
7.1
Sample preparation - Mix the sample of sugar thoroughly. Weigh 30 ± 0,02 g of raw sugar
into a 250 cm3 beaker. Add 70 cm3 of distilled water and dissolve using a magnetic stirrer
and follower. Filter the solution through a 0,45 µm (50 or 47 mm diameter) membrane under
vacuum (approximately 350 mm Hg) into a clean dry Buchner flask. Transfer this solution
into a 50 or 100 cm3 beaker. Adjust the pH of the solution to 7 ± 0,02 using either
hydrochloric acid (0,05 M) or sodium hydroxide (0,05 M). The solution must be stirred while
it is being brought into this pH range. Measure the absorbance of the solution on a
spectrophotometer in a 10 mm cell using distilled water as a reference. Measure the brix of
the solution using the bench refractometer.
NOTE: A ONE POINT CALIBRATION OF THE pH METER i.e pH 7 SHOULD BE
DONE BEFORE pH ADJUSTMENT.
8.
Expression of Results
8.1
Calculation - The brix (7.1) is corrected for temperature from Appendix A - Table 1. Use this
corrected brix to obtain the concentration of total solids in g/cm3 from Appendix A - Table
2
ICUMSA 420 Colour =
where
As
b
c
As x 10 000
bc
=
=
=
absorbance at 420 nm
cell length
concentration of total solids (g/cm3) as
determined from Appendix A - Table 2
Express results to the nearest 10 units.
EXAMPLE:
Obtain brix corrected for temperature from Table 1 in Appendix A.
Obtain concentration of total solids in g/cm3 from Table 2 in Appendix A, using the
corrected brix.
Refractometer reading at 20,8 C
Corrected brix at 20,8 C
Concentration of total solids (g/cm3)
Absorbance at 420 nm
=
=
=
=
51,2
51,3
0,634
0,620
223
ICUMSA 420 colour
=
0,620 x 10 000
10 x 0,634
Report to the nearest 10 units, i.e. 980.
9.
Precision
The tolerance between duplicates and between the control value and the standard values
obtained is 120 ICUMSA 420 units.
10.
Bibliography
10.1
10.2
10.3
ICUMSA Methods Book - Method GS1-7 (1994).
Laboratory Manual for South African Sugar Factories - 3rd Edition p324
Mellet P, Lionnet GRE, Kimmeling ZJ and Bennett PJ. Standards for the Analytical
Precision of Sugar and Molasses Analyses - Proc. S Afr Sug Technol Ass, 56 : 55-57
224
DETERMINATION OF THE COLOUR AND TURBIDITY IN SYRUP
1.
Scope and Field of Application
This method is applicable to syrups.
2.
Principle
A diluted sample of syrup is divided into two portions. One part is filtered under vacuum
through a membrane filter. Both the filtered and unfiltered samples are adjusted to pH = 7
± 0,02 and the absorbance is read on a spectrophotometer. The brix of both solutions are read
and the calculations done.
3.
Reagents
Use analytical grade reagents unless otherwise specified.
WARNING: Exercise caution when preparing and using the following reagents.
3.1
Distilled water
3.2
Hydrochloric acid 1 M - Measure 98 cm3 concentrated hydrochloric acid and dilute to 1000
cm3 in a volumetric flask.
3.3
Hydrochloric acid 0,05 M - Pipette 10 cm3 1 M hydrochloric acid into a 200 cm3 volumetric
flask and make to volume with distilled water.
3.4
Sodium hydroxide 1 M - Weigh 40,0 g sodium hydroxide pellets and dissolve in some
distilled water. Cool the solution and then dilute to 1000 cm3 in a volumetric flask.
3.5
Sodium hydroxide 0,05 M - Pipette 10 cm3 of 1 M sodium hydroxide into 200 cm3
volumetric flask and make to volume with distilled water.
4.
Apparatus
4.1
Spectrophotometer - Capable of light transmission measurements at a wavelength of 420 nm
with the narrowest practical bandwidth, e.g. ± 10 nm.
4.2
Optical glass cells - 10 mm
4.3
pH Meter - Calibrated to one point (Buffer 7)
4.4
Buchner flask - 500 cm3 + Buchner funnel 60 mm φ and rubber bungs to fit flask.
4.5
Beakers - 250 cm3, 100 or 50 cm3 with volume markings.
225
4.6
Membrane filters - 0,45 µm pore size, 50 mm or 47 mm φ Cellulose nitrate
4.7
Bench refractometer
4.8
Magnetic Stirrer - With follower
5.
Procedure
Mix the sample thoroughly. Prepare a solution of approximatley 5 brix by dissolving 7,0 g
of syrup in distilled water to a total volume of 100 cm3. Mix this solution on a magnetic
stirrer with a follower bar and divide the sample into two portions. One portion is filtered
through a membrane filter under vacuum. Adjust both the filtered and unfiltered samples to
a pH of 7 ± 0,02 and read the absorbance on the spectrophotometer at 420 nm using a 10 mm
cell. (Note: If there are fluctuations in the absorbances, then use a 5 mm cell). Read the brix
of these solutions and calculate colour and turbidity at 420 nm.
6.
Expression of Results
Calculation:
Colour of filtered portion at 420 nm = As x 10 000 = ICUMSA 420 Colour
bc
where As
b
c
=
=
=
absorbance at 420 nm
cell length in mm
concentration of total solids (g/cm3) [Refer Appendix A - Table 2]
The turbidity of the unfiltered solution is calculated as follows:
Turbidity = [(Absorbency index of unfiltered sample x 1000) - ICUMSA 420 Colour]
where the absorbency index of unfiltered sample = Aus x 10
bc
where Aus
b
c
=
=
=
absorbency of unfiltered sample at 420 nm
cell length in mm
concentration of total solids (g/cm3) See reference above.
Report colour and turbidity values to the nearest 10 units.
EXAMPLE:
The brix of the prepared syrup solution is 5 , therefore from Table 2 in Appendix A the total
solids in g/cm3 is 0,051 g.
Absorbance of filtered solution
226
=
0,531
Concentration of solution
=
0,051 g/cm3
ICUMSA 420 colour of syrup
=
0,531 x 10 000
5 x 0,051
=
20 824
Concentration of unfiltered solution
=
0,051 g/cm3
Absorbance (Aus) of unfiltered solution
=
0,741
Absorbancy index of unfiltered sample at 420 nm
=
Turbidity of syrup at 420 nm
0,741 x 10
5 x 0,051
=
29,06
=
(29,06 x 1000) - 20 824
=
8236
Report to the nearest 10 units i.e. 20 820 and 8240 for colour and turbidity respectively.
7.
Bibliography
7.1
Laboratory Manual for South African Sugar Factories - 3rd Edition p 287.
227
DETERMINATION OF THE COLOUR AND TURBIDITY OF WHITE SUGAR IN
SOLUTION
1.
Scope
This method is used for the determination of the colour and turbidity of white sugar in
solution.
2.
Field of Application
The method can be applied to all crystalline or powered white sugars, provided that a filtered
test solution can be prepared by the procedure specified in the method.
3.
Definitions
3.1
Transmittance of a solution - If I1, represents the radiant energy incident upon the first
surface of the solution and I2 represents the radiant energy leaving the second surface of the
solution. Then:T
=
I2/I1
=
transmittance of the solution
(100 T = percentage transmittance)
3.2
Transmittancy - Let Tsoln represent the transmittance of a cell containing the solution and let
Tsolv represent the transmittance of the same or duplicate cell containing the pure solvent.
Then:
T1 = Tsoln/Tsolv
3.3
228
=
log10Ts =
absorbancy of the solution
Absorbancy index (extinction index) - Let b represent the length, (mm), of the absorbing path
between the boundry layers of the solution and let c represent the concentration, (g/cm3), of
the sugar solution, Then:
As
3.5
transmittancy of the solution
Absorbance (extinction)
As
3.4
=
=
As
bc
=
absorbancy index of the solution
ICUMSA colour - The value of the absorbancy index multiplied by 1000 is reported as
ICUMSA colour. The resulting values are designated as ICUMSA units (IU), but since
measurements are made at a wavelength of 420 nm the value is designated as the ICUMSA
420 colour.
4.
Principle
White sugar is dissolved in distilled water to give a solution of 30 Bx. Some of this solution
is filtered through a membrane filter to remove turbidity while the remainder is retained.
Both the filtered and unfiltered solutions are adjusted to pH = 7 ± 0,02 using either
hydrochloric acid (approximately 0,005 M) or sodium hydroxide (approximately 0,005 M).
The absorbancies of both of these solutions are measured at a wavelength of 420 nm and the
ICUMSA 420 colour and the turbidity are calculated.
5.
Reagents
Use only reagents of recognized analytical grade and only distilled water or water of
equivalent purity.
WARNING: Exercise care when preparing and using the following solutions.
5.1
Hydrochloric acid 1 M - Measure 98 cm3 concentrated hydrochloric acid and dilute to 1000
cm3 in a volumetric flask.
5.2
Hydrochloric acid 0,005 M - Pipette 1 cm3 of 1 M hydrochloric acid into a 200 cm3
volumetric flask and make to volume with distilled water.
5.3
Sodium hydroxide 1 M - Weigh 40,0 g sodium hydroxide pellets and dissolve in some
distilled water. Cool the solution and then dilute to 1000 cm3 in a volumetric flask.
5.4
Sodium hydroxide 0,005 M - Pipette 1 cm3 1 M NaOH into a 200 cm3 volumetric flask and
make to volume with distilled water.
6.
Apparatus
6.1
Spectrophotometer - Capable of light transmission measurements at a wavelength of 420 nm
with the lowest practical bandwidth, e.g. ± 10 nm.
6.2
Optical glass cells - Glass cells of at least 50 mm in length should be used.
6.3
Membrane filters - Cellulose nitrate, pore size 0,45 µm, 50 mm or 47 mm φ
6.4
Buchner funnels - Porcelain - 50-65 mm φ
6.5
Buchner flask - 500 cm3 cacacity with rubber bungs to fit
6.6
Beakers - 250 cm3, 100 cm3 or 50 cm3
6.7
Measuring cylinder - 100 cm3
229
6.8
Watch glass - 60 mm φ
6.9
Refractometer - Bench type
6.10
pH meter - Calibrated to one point (Buffer 7)
6.11
Magnetic stirrer - With follower
6.12
Laboratory balance - Readable to 0,01 g
7.
Procedure
7.1
Sample preparation - Mix the sample of sugar throughly. Weigh 40 ± 0,02 g of the sample
into a 250 cm3 beaker, add 90 cm3 of distilled water and dissolve the sugar at room
temperature using a magnetic stirrer. Filter a portion of the solution through a 0,45 µm
membrane under vacuum and label S1. Label the remaining unfiltered portion S2. Adjust both
these solutions to a pH of 7 ± 0,02 using hydrochloric acid or sodium hydroxide. Measure
the absorbancies at 420 nm on the spectrophotometer using distilled water as a blank.
Measure the refractometer brix of these solutions.
Note: A one point calibration of the pH meter i.e. pH 7 should be done before pH adjustment.
8.
Expression of Results
8.1
Calculation - Calculate the concentration of solids, c, in solution, S1, from the refractometer
brix measured in 7.1 using Table 2 in Appendix A.
ICUMSA 420 colour =
where As
b
c
=
=
=
As x 10 000
bc
absorbance of S1 at 420 nm
cell length (mm)
concentration of total solids (g/cm3)
The turbidity of the unfiltered sugar solution (S2) is calculated as follows:
Turbidity
=
[absorbancy index of unfiltered sample x 1000] - ICUMSA 420
colour
where the absorbancy index of the unfiltered sample
230
=
and where
Aus x 10
bc
Aus
b
c
=
=
=
absorbance of unfiltered sample at 420 nm
cell length (mm)
concentration of total solids (g/cm3)
EXAMPLE:
ICUMSA 420 colour - obtain brix corrected for temperature from Table 4 in Appendix A.
Obtain the concentration of total solids in g/cm3 from Table 2 in Appendix A, using the
corrected brix.
Absorbance As at 420 nm of filtered solution
=
0,155
Refractometer reading of filtered solution at 23,5 C
=
49,52
Corrected brix at 20,0 C
=
49,80
Concentration of filtered solution
=
0,612 g/cm3
ICUMSA 420 colour
=
0,155 x 10 000
50 x 0,612
=
50,65
Brix reading of unfiltered solution at 23,5 C
=
49,54
Corrected brix at 20,0 C
=
49,82
Concentration of unfiltered solution
=
0,612 g/cm3
Absorbance Aus of unfiltered sample at 420 nm
=
0,205
Absorbancy index of unfiltered sample at 420 nm
=
0,205 x 10
50 x 0,612
=
0,0669
Report to the nearest unit, i.e. 51.
Turbidity
231
Turbidity
=
(0,669 x 1000) - 51
=
15,9
Report to the nearest unit, i.e. 16.
9.
Precision
The tolerance between duplicates and beween the control value and the standard values
obtained is
± 2 ICUMSA units.
10.
Bibliography
10.1
ICUMSA Methods Book - Method GS2/3-9 (1994)
10.2
Laboratory Manual for South African Sugar Factories - 3rd Edition p 337
232
DETERMINATION OF THE TURBIDITY AT 720 nm OF WHITE SUGAR IN SOLUTION
The above procedure is similar to that for the determination of turbidity @ 420 nm in white sugar
except for the calculation.
1.
Principle
A 30 Bx sugar solution is made. The pH is adjusted to 7,00 ± 0,02 and the absorbance is
then measured at 720 nm using a 50 mm cell.
2.
Procedure
The procedure to be followed is the same as that for turbidity @ 420 nm in white sugar
except that the solution absorbance is measured @ 720 nm. (Ref - Determination of the
Colour and Turbidity of White Sugars in Solution - TM025)
3.
Expression of Results
Calculation - The concentration of total solids in solution, c, is calculated from the
refractometer brix using Table 2 - Appendix A.
Turbidity @ 720 nm =
Aus x 10 000
bc
where Aus
b
c
absorbance
cell length (mm)
concentration of total solids (g/cm3)
=
=
=
EXAMPLE:
Obtain brix corrected for temperature from Table 4 in Appendix A.
Obtain concentration of total solids from Table 2 in Appendix A, using corrected brix.
Brix at 20 C
Absorbance Aus of solution at 720 nm
Concentration of solution at 720 nm
=
=
=
31,09
0,002
0,352
Turbidity of solution at 720 nm
=
0,002 x 10 000
50 x 0,352
=
1,14
Report to the nearest unit, i.e. 1
4.
Bibliography
4.1
Adaptation to Procedure - Laboratory Manual for South African Sugar Factories - 3rd Edition
p 337
Natbev (Coca-Cola) - Sugar Analytical Procedures
4.2
233