Good Practice Guidelines - jenway 7300 Operating Manual

3.3

GOOD PRACTICE GUIDELINES

1. For optimum performance all spectrophotometers should be sited in a clean, dry, dust
free atmosphere. When in use ambient temperature and light levels should remain as
constant as possible.
2. If required adherence to Standard Operating Procedures (SOP) and Good Laboratory
Practice (GLP) should be monitored with regular calibration checks and a suitable Quality
Control (QC) programme.
3. The sample chamber lid must be fully closed during measurement and before any
readings are recorded or printed.
4. The correct selection of sample containers is imperative for accurate and reproducible
results:
a) Check that the material of the sample container is compatible with the wavelengths to
be used for measurement. In general glass can only be used down to 360nm or
320nm depending on quality. Standard plastic cuvettes can be used down to 320nm.
Special UV versions can be used down to 260nm. Below this level quartz cuvettes
must be used.
b) Plastic disposable cuvettes should only be used ONCE.
c) Glass cuvettes should be thoroughly cleaned after use. Discard when scratches
become evident on optical surfaces.
d) Care should be taken when selecting semi-micro or micro cuvettes. The cuvette
window on the inner chamber (the area filled with sample) must be wider than the
aperture in the sample holder or light will reach the detector without passing through
the sample. In this case, semi-micro or micro cuvettes with self-screening black
surrounds must be used or, alternative holders for these cuvettes should be used.
e) Glass test tubes and other sample tubes should be used with care. Where possible,
matched tubes should be used and any index mark set to the correct position before
measurements are made.
f) Ensure any sample containers used are compatible with the constituents of both the
samples and standards they are to hold. Plastic cuvettes are not compatible with
organic solvents.
g) All sample containers must be handled with care; by the top, bottom and non-optical
surfaces only. Any finger marks evident must be removed by a suitable cleaning
process.
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