Instruction manual

4 Measurement
34
 What is the USP criterial value?
The USP criterial value is the upper limit of conductivity without temperature compensation
specified for each of the predefined temperature ranges from 0
°C to 100°C. The USP criterial
values are used for monitoring conductivity of pharmaceutical-grade water.
The USP 23 (United States Pharmacopoeia 23 Standards) requires pharmaceutical-grade
waters to have conductivity less than the values shown in Table 5, “Requirements on
temperature and conductivity, Stage 1”.
This instrument has the USP 23 criteria table in it to determine the upper limit of conductivity
automatically based on the measured temperature before compensation is made.
Ex.)
The limit of conductivity for 15
°C is 1.0 µS/cm in the table shown below. If you have set the
safety factor to 50%, an alarm is issued when the conductivity is detected to be 0.5
µS/cm or
more at 15
°C.
Table 5 Requirements on temperature and conductivity, Stage 1
Temperature range
(
°C)
Conductivity limit
(µS/cm)
Temperature range
(°C)
Conductivity limit
(µS/cm)
0 ≦
°C ＜ 5
0.6
50 ≦ °C ＜ 55
1.9
5 ≦
°C ＜ 10
0.8
55 ≦ °C ＜ 60
2.1
10 ≦
°C ＜ 15
0.9
60 ≦ °C ＜ 65
2.2
15 ≦
°C ＜ 20
1.0
65 ≦ °C ＜ 70
2.4
20 ≦
°C ＜ 25
1.1
70 ≦ °C ＜ 75
2.5
25 ≦
°C ＜ 30
1.3
75 ≦ °C ＜ 80
2.7
30 ≦
°C ＜ 35
1.4
80 ≦ °C ＜ 85
2.7
35 ≦
°C ＜ 40
1.5
85 ≦ °C ＜ 90
2.7
40 ≦
°C ＜ 45
1.7
90 ≦ °C ＜ 95
2.7
45 ≦
°C ＜ 50
1.8
95 ≦ °C ＜ 100
2.9
100
°C or more 3.1
USP 23 conductivity requirements
Conductivity limit [µS/cm]
Temperature range