Manual

4 Notes – Maintenance – Faults

750 Autosampler

Fig. 11: Transfer needle replacement

4.2.3 Sample preparation

Experience has shown that most problems are caused by solids in the

sample solutions. Such particles can block the needle, transfer tubing

and the sample loop and also permanently damage the surfaces of the

injection valve seals. This is the reason why all samples must be filtered

before they are filled into the sample vials (procedure see chap. 4.1.2).

Solids may also be formed by the precipitation of buffer salts in the IC

system. With buffered samples it is recommended that the sample loop

feed is rinsed with a large volume of pure water after sample injection.

For example, this can be achieved by filling several (e.g. 5) sample vials

in sequence with distilled water after each sample and programming

them as rinsing samples without run time. This procedure also avoids

corrosion damage to the injection needle and the crystallization of salts.

1717 Needle holder

55 Transfer needle

1616 Ferrule

PEEK compression fitting 1818

Nut 1919

Connection screw 2121

Centering sleeve 2424

Clamping ring 2222

Holder 2323

Holder 2020