TBS-380 Mini-Fluorometer Operating Manual
13
5 Troubleshooting
The following list defines potential problems that a user may encounter.
5.1
Low or No Reading
Check with the Solid Standard to determine if the instrument is functioning properly.
Are all the reagents and standards made to specification? Are any of the reagents expired? Is the
dilution done correctly?
Has the sample been exposed to light for an extended period? Some fluorescent dyes are
susceptible to photodegradation. It is recommended that the dye solution be protected from the
light.
Is the right optical channel selected for the application? Has the instrument been calibrated prior
to reading?
Is the sample in a detectable, linear range for the instrument? Sample concentration might be too
low or too high to be detected (see 4.2).
Is the right type of cuvette being used? Methacrylate cuvettes should be used for UV applications.
Check temperature (see 4.3).
Does the sample volume meet the minimum requirement? The minimum volume is 2 mL for
10x10 mm cuvette, or 50
µ
L for Minicell.
Is the Minicell adaptor inserted in the correct orientation? If the BLUE channel is selected, insert
the Minicell adaptor in the sample compartment with the tab away from you and the BLUE label
facing you. If UV channel is selected, insert the Minicell adaptor in the sample compartment with
the tab close to you and the “UV” label facing you.
Is the orientation of the Minicell cuvettes consistent (see 4.4)?
What is the RFU (Relative Fluorescence Unit) of the blank and calibration standard? Press the
DIAG
button and
ENTER
to display the RFU values (see 3.8). If the instrument was calibrated
with the highest concentration standard and the RFU of the standard is too close to that of the
blank, the sample readings may be out of the instrument’s detection limit.
Ideally:
RFU-STD
≥
3
RFU-Blk
5.2
High or Over Reading
Dilute samples and standards.
5.3
Fluctuating Results
Check the Solid Standard to determine if the instrument is functioning properly.
Check for spills in the sample compartment.
Check the volume of the sample.
The minimum volume is 2 mL for 10x10 mm cuvette, 50
µ
L for the Minicell.
Check that the reagents and cuvette material are compatible.
Check temperature (see 4.3).
Confirm that the RFU-STD is greater than RFU-Blk by factor of
≥
3.