The presence of optical brighteners (also known as fluorescent whitening agents) is determined qualitatively by shining an ultraviolet lamp onto the product and viewing a glow known as fluorescence. Qualitative Determination for the Presence of Optical Brightener
Apparatus
1. Ultraviolet light source, ie. UV
Lamp, available from Fisher Scientific; can be hand-held or battery-powered.
2. Darkened viewing area, such as a
fume hood or room with the light source turned off.
Reagents
None
Procedure
1. Turn on the UV lamp.
2. In a darkened viewing area shine
the UV lamp onto the sample in question.
3. If the sample displays a
"glow" or seems to be self-luminous (ie: a whitish/ bluish/purplish
glowing colour) then it displays fluorescence and thus optical brightener is
qualitatively identified.
Calculations:
None
References:
R&C NB#324-123.
Raw material Physical Description
This method is used for testing raw materials, premixes, intermediates and finished products. This test is not used for the evaluation of the odour of fragrances.
2 REFERENCES
2.1 Manufacturer's or Supplier's Datasheets for Raw Materials.
2.2 EP/BP/USP For raw materials.
2.3 Finished Products Specified by the
R & D Chemist during the compilation of the specification.
3 DEFINITIONS
3.1 Reference Standard, a sample of the
material which is known to be satisfactory and has been retained in good
storage conditions for comparison purposes.
4 PRINCIPLES
To test, by comparing with a reference
standard, the smell, colour, appearance and consistency of raw
materials, premixes, intermediates products and finished products by olfactory,
visual and, if necessary, tactile evaluation. The test is a qualitative one and
does not use any form of quantitative measurement.
Test 23725 is used for the
quantitative assessment of colour and clarity.
REFERENCE MATERIAL
5.1 The reference standard needs to be labelled with name, batch and date of material which will normally be in a clear stoppered vial. The label needs an expiry date when it is required to replace it with a newer reference sample.
Normally the reference samples are
best stored between 0° - 5°C and retained in the dark. Liquids, in particular, may deepen in colour with age and need to be replaced fairly frequently.
6 CHEMICAL REAGENTS - not applicable
7 EQUIPMENT
Beakers, test tubes or sample jars
made of glass or ones which are completely transparent.
8 INTERFERENCES
8.1 Temperature may affect the appearance
of liquids and the material may well range from a crystalline solid through a
paste to a clear liquid depending on temperature. Temperature is therefore an
important factor.
8.2 The lighting conditions will also
affect the colour. Both reference standard and test material need to be viewed under
the same conditions of lighting and in the same type of container.
8.3 When sniffing the material, the
test again should be done under similar conditions if compared against a
reference material.
8.4 The reference material may differ from the test material in many cases such as the size of granules or differences in the shade of colour. This subjective test, therefore, depends on subjective judgement.
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