Jenway 3540 - Manual (Page 7)

1.5 Good Practice Guidelines – pH
1.
Selection of the correct electrode for your application is the most important factor in
achieving good performance and extended electrode life. The use of Application
Specific electrodes is recommended for all but the simplest sample matrix and
measurement conditions. Please contact Jenway if you require further help or advice
on electrode suitability and application support.
2.
For best results follow Good Laboratory Practice (GLP) at all times. Ensure regular
calibration using buffer solutions with values that bracket the expected sample pH
levels. Always record the sample/buffer temperature with its corresponding pH value.
3.
Always ensure that all buffer solutions and reagents used are within their expiry
dates. Never return unused solutions to the bottle, nor insert the electrode directly
into the bottle. Always replace caps on their respective bottles immediately after use.
4.
Ensure that the correct buffer set is selected (e.g. NIST, DIN, JIS, etc), or that the
temperature corrected value of the buffer is used for calibration, NOT the nominal
value.
5.
Recording the electrode Offset and Slope values after each calibration will enable
electrode condition to be monitored and the most effective calibration and
maintenance procedures to be implemented.
6.
Ensure BOTH pH and temperature values are stable before recording results or
confirming calibration. Where sample and/or buffer temperature vary, or are
significantly different from ambient, greater accuracy and faster analysis can be
achieved by keeping buffers, samples, rinse solution, electrode and ATC probe in a
water bath or other temperature controlled environment.
7.
Ensure the electrode is rinsed with deionised water between each sample and
calibration buffer.
DO NOT touch the sensitive pH glass membrane or reference junction. Excess liquid
may be removed by gentle blotting with a soft tissue.
DO NOT rub the electrode as this may cause an electrostatic charge.
8.
For Refillable Electrodes:
Ensure that the electrode’s outer chamber is at least two thirds full. Always use the
correct fill solution for the electrode. Use of the wrong solution WILL cause
irreversible damage. Always open the fill port during use.
9.
DO NOT immerse any electrode below the level of the internal fill solution (except for
those designated as submersible).
10.
Always use electrodes within their specified temperature range. Degradation of
electrodes used above their operating temperature is rapid and irreversible.
11.
Always use and store the electrode in an upright vertical position. Ensure no air
bubbles are trapped in the internal solutions. Air bubbles may be removed by gently
shaking the electrode in a downward direction.
12.
Regular electrode cleaning and maintenance will improve performance and extend
working life. Use only cleaning solutions and procedures detailed in the instructions
supplied with the electrode. Others may damage the electrode and degrade
performance.