Jenway 6285 - Manual (Page 5)

1.2 Good Practice Guidelines
1. The selection of the optimum excitation and emission wavelengths (filters) is
critical to achieving the best performance from the analysis.
2. All fluorimeters should be sited in a clean, dry, dust free environment. When in
use ambient temperature and light levels should remain as constant as possible.
3. Adherance to Standard Operating Procedures (SOP) and Good Laboratory
Practice (GLP) should be maintained, with regular calibration checks and a suitable
Quality Control (QC) programme.
4. The correct selection of cuvettes is imperative for accurate and reproducible
results:
a) Ensure all cuvettes used are compatible with fluorimetric measurements
where the emission beam is at 90° to the excitation source. Typical examples
have 4 clear sides.
b) Ensure any native fluorescence from the cuvette material is minimal at the
analysis wavelengths.
c) Plastic cuvettes should be used once only.
d) Glass and quartz cuvettes should be thoroughly cleaned after use. Discard
when scratches or marks are evident in their optical surfaces.
e) Ensure any cleaning agents used do not fluoresce at the analytical
wavelengths and are thoroughly rinsed away before drying.
f) Ensure the cuvettes used are compatible with the constituents of both the
samples and standards they are to hold. Plastic cuvettes are not compatible
with some organic solvents.
g) Cuvettes must be handled with care; by the top and non-optical surfaces only.
Any finger marks must be removed by using a suitable cleaning process.
h) Flow through cuvettes must be selected with additional consideration for the
sample type, aspirated volume, pumping system and rinse cycle, as well as
the waste handling to be used.
5. The high sensitivity of fluorimetric analysis means that all glassware used in the
preparation of samples and standards must be totally free from contamination.
6. Chemicals and reagents used in sample and standard preparation should be of
the highest grade of purity (AR Grade) and all should be checked for excessive
background fluorescence at the analytical wavelengths.
7. Samples and working standards should not be stored due to the effects of
evaporation, as well as chemical and photo-degradation. Only prepare samples and
working standards when they are required for analysis.
8. Fluorescence is inversely proportional to temperature. Ensure that all samples
and standards have equilibrated to ambient temperature before analysis. If in doubt,
use a temperature controlled cuvette holder.
9. Refrigerated or cold samples will form micro-bubbles on the cuvette wall as they
warm up. These are a common cause of drift in readings. Ensure all samples and
standards have equilibrated to ambient temperature before analysis.
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