Metrohm 711 Liquino - Manual (Page 126)

4.9 GLP mode - validation
711 Liquino, Instructions for use 120
4.9 GLP mode - validation
With the 711 Liquino Dosinos or dosing units can be comfortably validated.
Checking can be carried out with the GLP mode.
Validation of dosing units
With one cylinder filling of the dosing unit up to ten random volumes are
dosed out and weighed accurately. Using the density of the liquid the vol-
ume of the liquid weighed out is calculated and compared with the theoreti-
cal dosed-out volumes.
For each individual dosing the absolute and the relative dosing errors are
calculated. The mean value of the absolute dosing error in µL is used to as-
sess the dosing accuracy.
The Liquino calculates the linear regression of actual volumes against theo-
retical volumes and determines the slope of the regression curve and the Y-
axis intercept. For details see Metrohm Application Bulletin 238, 'Dosimat
Test according to GLP/ISO'.
For the validation relevant limiting values for the absolute error, slope and
the Y-axis intercept can be individually set. This is part of the configuration
of the 711 Liquino. Details can be found on page 69ff of these ‘Instructions
for use’.
Requirements
You require the following items to carry out a validation:
•
Dosing unit with dosing tubing at port 1, buret tip 6.1543.060 (without dif-
fusion-reducing valve)
• Bottle with degassed water or other liquid of known density. The dosing
unit is mounted on the bottle with the dosing drive (Dosino).
• Analytical balance with a resolution of at least 0.1 mg. If possible, con-
nect the balance directly to the Liquino. The required connection cables
are listed on page 19. However, it is also possible to enter the weight of
the dosed amount of liquid directly via the Liquino keyboard.
• Printer with serial interface. The required connection cables are listed on
page 17ff.
If only a parallel Centronics interface is available on the printer then a se-
rial/parallel converter SP 1000 (2.145.0300) can be used to make the
connection.
• If printer and balance are to be connected at the same time then an
adapter cable (6.2125.010) and a branch plug (6.2125.030) must be
mounted on the RS232 interface.
• Narrow neck Erlenmeyer flasks
• Officially calibrated thermometer
Procedure
• Measure the temperature of the liquid to be dosed.
• Position the test setup so that it is protected from direct sunlight and drafts.
The series of measurements must be carried out without any interruptions.
• Mount the buret tip on a support rod. It must not be moved during the series
of measurements.
If possible lead the buret tip into the weighing chamber directly from above
Theoretical
volume
y-axis intercept