Turner Designs TD-700, Руководство по эксплуатации

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TD-700 Laboratory Fluorometer Operating Manual
Page 30
APPENDIX 1
Before Calibration or Reading Samples
A. Materials Needed
- 1 or more cuvettes (25 mm test tubes; 13 mm test tubes or 10 mm
square cuvettes).
- A Blank (sample water or liquid containing none of the fluorescent
material) (except when using the instrument in Simple Mode).
- Standard(s) (1 to 5 solutions of varying but known concentrations) for
the Direct Concentration Calibration Procedure; OR, for the Simple
mode, one standard that is approximately half the level of the highest
sample you are likely to read (used to set the optimal sensitivity and
range of the TD-700).
- Samples to be read.
B. When Handling Samples
1. Take care not to spill samples into the sample chamber. Wipe up any
spills promptly. See Appendix 9, Section A, for details on mainte-
nance.
2. Rinse the test tube or cuvette 3 times between samples (preferably
with the sample to be read). The TD-700 is very sensitive and even
small amounts of material from a previous sample may result in errors.
Complete rinsing is especially important if you are using the same test
tube or cuvette for samples and blank.
3. Fill the test tube or cuvette at least 75% full; significant error will result
if it is not full enough.
4. The cuvette MUST BE DRY on the outside when taking readings.
Moisture on the outside will result in error.
C. Linear Range and “Quenching”
The linear range is the concentration range in which the readout of the TD-
700 is directly proportional to the analyte concentration. The linear range
begins with the smallest detectable concentration and spans to an upper
limit (concentration) that is dependent upon: the properties of the fluores-
cent material, the filters used, and the path length.
Beyond the linear range (above the upper concentration limit), the fluores-
cence readings rise at a decreasing rate and a calibration curve is neces-
sary for accurate readings. At even higher concentrations, readings will
begin to decrease even though the sample concentration is increasing.
This effect is known as "concentration quenching".