PerkinElmer LS 55, Руководство пользователя

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118 . LS 55 User’s Guide
Operation
1. Prepare a solution of the sample for measurement.
Suitable solvents are ethanol, cyclohexane or mehtylcyclohexane or a mixture
of diethylether, isopentane and ethanol (EPA) in the ratio 5:5:2.
CAUTION
Do not use water as solvent, the pressure caused by freezing
will burst the capillary.
2. Using a narrow pipette, fill a clean, dry sample tube to a depth of at least
30 mm (equivalent to approximately 100
μ L of sample).
Ensure that the sample is free of bubbles.
3. Wipe the outer surface of the tube dry.
4. Remove the empty tube from the sample holder and replace with the sample
tube, replace the sample cover.
The sample cover should be open for as short a time as possible to avoid
condensation build-up in the sample holder area.
5. Observe the sample cooling by monitoring sample signal against time,
preferably with the Fl WinLab TimeDrive application.
The sample should require about 1 minute to reach 77 K.
6. Measure the sample fluorescence or phosphorescence as desired.
If the measurement takes more than ten minutes, the sample tube should be
rotated through 360 degrees to avoid liquid carbon dioxide building up in the
sample holder area.
NOTE: A potential problem is snowing of the solvent. In this case, the solvent does
not freeze to a clear glass, but shows white flecks. This can be determined
by rapidly removing the tube and observing it. If snowing occurs, this does
not prohibit qualitative and quantitative analyses, but gives much higher
background levels and lowered sensitivity. The snowing effect may be
removed by changing the solvent. Methylcyclohexane, for example, forms a
clear glass, while hexane forms a snow.
NOTE: The circular cross-section of the sample tube can cause stray light to be
reflected into the emission light path. Select one of the emission cut-off
filters (see the FL WinLab Software User’s Guide) to remove second- and
third order stray light from spectra.