Metalyser
®
Portable HM1000
Instruction Manual v 5.0
21
5.3. ANALYSIS
Before performing a test using the Metalyser
®
, ensure that the working electrode has been
successfully plated and conditioned first for the metal of interest.
(See section 5.2. Plating and the relevant application notes)
There are two ways to analyse a sample, either via the Standard Addition method or by an
in-field calibration of the instrument.
1.
Standard Addition:
This is the recommended method of analysis, where
the used adds a known amount of standard to the solution, producing a
known peak height. The Metalyser will first run a scan of the sample, to
determine if the metals are present and measure the response. A prompt
will be given to add a standard to the sample; this is done using the pipette
provided. A fixed volume of standard is added to the SAB which will produce
the increase in peak height from which the initial sample concentration can
be calculated.
2.
The in-field calibration method establishes a calibration curve first before
analysing a number of samples rapidly. The Metalyser
®
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
Metalyser
®
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.
The
Blank Subtraction
method is used for creating a new baseline for the
instrument for the analysis. It is to be used only when a suspected contaminant is
present in the buffers being used. Performing this will replace the previous blank.
After each analysis the sonde head and the electrodes are to be washed
thoroughly. This is in order to minimise carry-over and to clean off all traces of
the previous analysis. This can be achieved by using the deionised water or by
washing the sonde head (without the SAB) in the sample water. This is particularly
important following an arsenic analysis.
