Metrohm 864 Robotic Balance Sample Processor - Manual (Page 9)

￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 1 Introduction
864 Robotic Balance Sample Processor ￭￭￭￭￭￭￭￭ 1
1 Introduction
1.1 Instrument description
The 864 Robotic Balance Sample Processor is a laboratory automation sys-
tem with integrated pipetting and weighing equipment. It was designed
for the fully automatic determination of TAN (Total Acid Number) and TBN
(Total Base Number) in liquids, such as e.g. petrochemical products, cool-
ing oils, etc.
The basis of the system is comprised of one Sample Processor with two
towers as working stations and one multi-row sample rack which is
designed for the weighing of the sample vessels. The sample rack can
hold up to 20 liquid samples. One working station is equipped for the
pipetting of the samples, the other is equipped with titration equipment.
The weighing of the sample vessels is accomplished with an analytical bal-
ance which is provided with a special weighing equipment. Three 800
Dosinos are available as dosing drives. One 809 Titrando is used for the
titrations. The rinsing and aspiration of liquids is accomplished with one
843 Pump Station in the version that has two peristaltic pump drives. The
entire system is controlled by the tiamo
™ software, which contains one
high-performance database for the determination data.
Mode of operation
Vessels filled with samples, as well as empty vessels and pipetting tips, are
placed on the sample rack. The rack is rotated in an automatic sequence
in such a way that one empty sample vessel on a weighing pan in the out-
ermost row of the rack is pushed onto a weighing position. There it is
tared.
The robotic arm on Tower 1 takes up one of the pipetting tips, which is
kept in readiness on the innermost row of the rack. With the aid of a dos-
ing drive, a defined volume of a liquid sample is aspirated into the pipet-
ting tip. The content of the pipetting tip is expelled into the tared sample
vessel on the weighing position. The balance sends the weight of the
pipetted sample to the control software.
Rotation of the sample rack causes the weighed sample vessel to be trans-
ported to the second processing station. There the solvent is added, stir-
red and the actual determination is carried out. The sample solution is
aspirated after the titration has been completed. Electrodes and tubing
are rinsed by efficient spray nozzles. Optionally, the rinsing can take place
in an external rinsing station, which should also remove even tenacious
residues.