Metrohm 711 Liquino - Manual (Page 63)

3 Introduction
711 Liquino, Instructions for use 57
3.2.12 GLP – automatic validation
For the automatic validation of a Dosino or the dosing unit a balance
*) must
be connected to the 711 Liquino via the RS interface (see also page 19). In
the GLP mode the Liquino automatically adds liquid to a tared vessel on the
analytical balance, calculates the volume of the liquid added and compares
this with the theoretical volume. The validation protocol is printed out on the
connected printer in agreement with GLP practice.
The liquid used in this example is distilled water, which has advantages
when used for this test.
Preconditions / Preparation
The connection of the printer and balance is described on pages 17 and 19.
A dosing unit which corresponds to the tubing of the Dosino used must be
defined. This process is described on page 22.
The following instruments and accessories must be available:
• dosing tubing on Port 1 of the Dosino with buret tip 6.1543.060 (without
diffusion-reducing valve)
• bottle filled with degassed water onto which the Dosino is screwed
• analytical balance, resolution 0.1 mg
• narrow-neck Erlenmeyer flask
• calibrated thermometer.
Make the following preparations:
• Measure the temperature of the water to be added. Set up the test appa-
ratus so that it is not exposed to direct sunlight or draughts. The series of
measurements must be carried out without any interruption.
• Mount the buret tip firmly on a support rod. It must not be moved during
the test.
If possible lead the buret tip into the balance chamber directly from
above (cover the top of the balance chamber). Place the Erlenmeyer
flask on the balance.
It is important that during the addition the stream of liquid breaks off
cleanly each time. This means that special precautions must be taken for
some cylinder volumes:
2mL: attach a yellow Eppendorf pipet tip to the buret tip. Insert a piece of
absorbent cotton in the Erlenmeyer flask and fasten the buret tip so that it
just does not touch the wad of cotton.
5, 10, 20 mL: attach a yellow Eppendorf pipet tip to the buret tip.
50 mL: attach a blue Eppendorf pipet tip to the buret tip.
*) It is also possible to work without any direct connection between the balance and Liquino. The correspond-
ing weight must then be entered via the keyboard.