Metrohm 711 Liquino - Manual (Page 101)

4. Detailed description
711 Liquino, Instructions for use 95
Dosing procedure
The necessary weight of the original substance is calculated when the
<START> key of the Liquino is pressed and shown as a suggestion. The
effective sample weight can then be accepted automatically by the balance
or entered manually. The volume to be dosed is calculated from the effec-
tive sample weight and displayed. Dosing is carried out after confirmation
with <ENTER>.
Note
If the effective weight of the original substance does not correspond to the
amount calculated by the Liquino then the final volume will not correspond
exactly to the target volume.
4.6.2 Standard solutions / Dilutions
The CONT mode of the 711 Liquino is extremely suitable for preparing
standard solutions, particularly series of dilutions. When the concentration of
the standard solution and the target volume have been defined then the
Liquino automatically calculates the volume of the standard solution to be
dosed in for the different target concentrations of a dilution series.
There is the possibility of documenting the preparation of a standard solu-
tion or a dilution series with the printout of a result report.
The dosing procedure
'Volume fraction' is used for the preparation of dilu-
tions and supports the following quantities or mass units:
mol/L, ppm, g/L, %
It is assumed that dosing is carried out into volumetric flasks and that the
Dosino with dosing unit is mounted on the
standard solution bottle.
The necessary information can be stored as a method. These are:
− mass unit of target concentration
− target volume in mL
− content of standard solution
Dosing procedure
After the <START> key is pressed the Liquino requests the target content
of the standard solution. The volume to be dosed in is calculated from this
target content and displayed. After confirmation of the volume to be dosed
in with <ENTER> dosing is started. When dosing has been completed
<START> can be pressed again and the target content of the next stand-
ard solution can be entered. In this way a dilution series can be prepared
comfortably.
Note
The volumetric flasks with the standard solutions can of course also be filled
up to the mark by the Liquino. This is done by using the manual functions
'DOSING' and 'DISPENSE'. The 'DOSING’ function with increasing dosing
rate (see page 24ff) is extremely suitable for drop-by-drop dosing which is
required when filling a volumetric flask up to the mark.