Metrohm 711 Liquino - Manual (Page 100)

4.6 CONT mode - preparation of solutions
711 Liquino, Instructions for use 94
4.6 CONT mode - preparation of solutions
The CONT mode (content) allows the comfortable preparation of solutions
or dilutions. With the 711 Liquino the required concentration of the solution
can be set precisely. Various dosing procedures are available.
The port allocation of the Dosino in the CONT mode is defined as follows:
4 2
1 3
Port allocation
Port 1
Dosing port
Port 2 Filling port (with dipper tube)
Port 3 empty
Port 4 Waste (for PREP function)
The port allocation cannot be altered via
the keyboard.
4.6.1 Preparation of solutions
If a 711 Liquino is used it is not necessary to weigh out the required amount
of a substance with total accuracy. In the CONT mode the Liquino automat-
ically calculates the required volume of solvent needed to obtain the neces-
sary concentration with the sample weight used, e.g. for a standard solu-
tion.
A balance can be connected directly to the 711 Liquino via an RS232 cable
so that the preparation of standard solutions can be automated to a large
extent.
There is the possibility of documenting the dosing by printing out a result
report. The simultaneous connection of a balance and a printer is possible
(with branch plug 6.2125.030 and cable 6.2125.010).
Depending on the unit of mass of the target concentration the following dos-
ing procedures can be used for the
preparation of solutions:
Mass unit Type of calculation
mol/L molar fraction concentration
g/L mass concentration
% (percent by weight) mass fraction
The necessary information can be stored as a method. These are:
− target content (in mol/L, g/L or %)
− target volume in mL
− factor (e.g. relative content of original substance in g/g)
− molar mass (only for molar fraction concentration)
− density of solvent in g/mL (only for mass fraction)
It is assumed that the Dosino with dosing unit is mounted on a
solvent bot-
tle.