Influence Of Foreign Substances; Dosing Of Reagents - wtw PhotoLab S6 Operating Instructions Manual

2. Photometric Test Kits

2.2.5 Influence of Foreign Substances

Foreign substances in the sample solution can
raise the measurement value as a result of an
amplification of the reaction, or
lower the measurement value as a result of a
prevention of the reaction.
A quantification of the effects is stated in tabular
form in the respective package inserts for the most
important foreign ions. The tolerance limits have
2.2.6 Dosing the Reagents
Small amounts of liquids are dosed by counting the
number of drops from the leakproof bottle.
Larger amounts of liquids are dosed with the piston
syringe enclosed with the respective test kit.
Handling:
Depress the piston of the
syringe to the zero position.
Place the tip of the syringe
firmly on the leakproof attach-
ment of the bottle.
In some cases in which an exact dosage of – gene-
rally small – quantities of reagent is called for, it is
necessary to conduct the dosage procedure using a
positive-displacement pipette; this is described in
detail in the analysis instructions.
Solid substances are dosed either with the dose-
metering cap or with microspoons that are integrated
VI
Turn the bottle with the piston
syringe 180° so that the piston
syringe is positioned
underneath the bottle.
been determined for the individual ions; they may not
be evaluated cumulatively.
Suitability for use in salt water
A tabular survey (see pages XVI – XVII) provides infor-
mation on the suitability of the tests in connection
with salt water and also on the tolerances for salt
concentrations.
When using a dropping bottle, it is imperative that the bottle be
held vertically and the reagent be slowly added dropwise
(approx. 1 drop per second). Otherwise the correct drop size will
not be achieved and the amount of reagent will be incorrect.
Slowly withdraw the piston
downwards to the required
volume (orientation aid: upper
edge of the piston ring!). In the
event that air bubbles are dra-
wn into the syringe with the
reagent, the syringe contents
must be pressed back into the
bottle and the filling process
repeated.
into the screw cap of the respective reagent bottle.
The dose-metering cap (colour green: volume
0.025 ml; blue: 0.050 ml) can be used in cases when
the solid substance or mixture is free-flowing. In all
other cases the substances are dosed using the
microspoon (colour grey: volume 0.01 ml;
green: 0.03 ml; blue: 0.1 ml).
Once the syringe has been fil-
led free of air bubbles, turn the
bottle with the piston syringe
180° back to the original posi-
tion. Remove the filled piston
syringe from the attachment of
the bottle and carefully inject
the contents into the reaction
vessel.
Release 07/03