ALTANA LCM IV - Manual (Page 59)

60
Standard programs
There are two ways of color matching of a sample with the
Ph.Eur.system.system:
•
Automatic: The color of the solution is compared to the
colors of the 37 color reference solutions. The identifier of the
reference solution whose color is closest to that of the sample
(i.e. the reference solution with the smallest color difference
' E* to the sample) is displayed.
• Specified scale: A scale is specified (e.g. BY). The identifier
of the reference solution whose color is closest to that of the
sample (i.e. the reference solution with the smallest color
difference 'E* to the sample within the specified scale) is
displayed.
If a scale is defined (e.g. scale BY), one of the following five
symbols is used to define the relationship between the measured
results and the scale (see Table 5 ).
The 'L*, 'a* and 'b* values are the numerical differences
between the L*, a* and b* values of the samples and the
displayed Pharmacopeia color reference solution. The
measurements can be taken using cuvettes with 10 mm, 11 mm
or 50 mm path lengths. The CIE L*a*b*values depend on the path
length and are always related to the type of cuvette/sample cell
employed. The longer the path length, the better the measuring
accuracy.
1. Insert the test cuvette.
The result of the color calculation is displayed.
2. Press the Auto B 4 touch-sensitive area.
Table 5 Specified scale
Character Description
= equal The color number of the sample is equal to that of the reference solution
< less The color number of the sample is less than that of the reference solution
> greater The color number of the sample is greater than that of the reference solution
<> between The color number of the sample is between those of two reference solutions
-> next
The color numner of the sample does not match any reference solution in this scale, but the
indicated reference solution is nearest in color