46
Standard Operations
5.5.1.4 Change the measuring range after a measurement
1.
Press the upper or lower limit of the bar graph (touch-sensitive
area 5 or 6).
2.
Enter the new limit and press
OK
to confirm.
Note:
It is only possible to change the limits inside the measuring range of
the color scale. It is not possible to extend the range, e.g. to Hazen 2000.
The current result and all further measurements will be displayed
with the new measuring range.
5.5.2 Take a Pharm. Eur. color measurement
The LICO 500 method of determining color in accordance with the
European Pharmacopoeia (Ph.Eur) corresponds to the
specifications in Chapter 2.2.2 of the pharmacopoeia "Degree of
coloration of liquids ", in which a total of 37 color reference solutions
(CRS) are defined for the hues yellow (Y1-Y7), greenish-yellow
(GY1-GY7), brownish-yellow (BY1-BY7), brown (B1-B9) and red
(R1-R7). Each color reference solution is unambiguously defined in
the CIE Lab color space in terms of its brightness, hue and
saturation.
There are two ways of color matching of a sample with the Ph.Eur.
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
DE* 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 within the specified scale (i.e. the reference solution
with the smallest color difference DE* to the sample within the
specified scale) is displayed.
If a scale is specified (e.g. BY scale), one of the following five signs
is used to define the correlation between the measurement results
and the scale (see
).
Table 5 Specified scale
Sign
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
->nearest
The sample does not match any reference solution in this scale, but the indicated reference
solution is nearest in color
