Arsenometer HMAS100
Instruction Manual v2.0
2.3.3. ANALYSIS
Before using the Arsenometer to perform a test ensure that the working
electrode has been successfully plated and conditioned first.
There are now two ways to analyse a sample, either via the Standard
Addition method or by an in-field calibration of the instrument.
1. The normal method of analysis for the Arsenometer is for the user
to add a known amount of standard to the solution giving a
known peak height, the
Standard Addition
method. The
instrument then determines the value for the unknown sample
previously analysed.
2. The in-field calibration method establishes a calibration curve first before
analysing a number of samples rapidly. The Arsenometer firstly needs to
establish the calibration curve using the Calibrate option in the menu of each
metal of interest. Once this has been successfully completed an
Analyse
Sample
can be undertaken
(Note: using
Analyse Sample
without establishing a new calibration curve, the
previous calibration will be used which may not be correct for the current
analysis).
The calibration needs to be established just prior to analysis and also after a
new plate has been applied to the tip of the working electrode. Many factors
affect the calibration curve and the greater the time the analysis occurs after
the calibration curve was established the greater the chance that there will be a
decrease in accuracy. This is due to a number of factors including variability
with the plate over time and even the components of the solution changing. It is
important when calibrating the instrument that it is calibrated on a similar type
of water to that being analysed, i.e. if a river sample from a particular river is
being analysed then the Arsenometer needs to be calibrated using that river
water, if a new river is to be analysed then recalibrate using a new river sample
from the new location.
