Instructions come from these articles listed below.
Cyclops-7F and C-FLUOR: https://docs.turnerdesigns.com/t2/doc/instructions/998-6800.pdf
AquaFluor and Trilogy: https://docs.turnerdesigns.com/t2/doc/instructions/998-0025.pdf
TD-700: https://docs.turnerdesigns.com/t2/doc/manuals/7000-998.pdf
A solid secondary standard contains a stable fluorescent material that is intended to give you consistent repeatable readings. The solid secondary standard is a great tool for tracking instrument performance after calibration with a liquid primary standard. On a periodic basis, before making measurements with the instrument, use the solid secondary standard to verify the calibration. If the solid secondary standard value has changed by more than ± 5% of its assigned value, the instrument should be recalibrated.
Solid Secondary Standards should be stored at room temperature (around 20 degree Celsius) in the case when not in use and kept free of dust and moisture. Special care must be taken with the Solid Secondary Standard to ensure that it is not exposed to UV light for prolonged periods of time. This can result in degradation of the standard
There are a variety of ways to use it and I can break down those instructions into smaller snippets for you.
Options for usage:
1. Using recently calibrated device with liquid standard for Dye Tracing Applications - certain value stated. Adjust solid standard to be close to value. From that point on, use the solid standard as a check on the calibration values of the instrument. The solid standard cannot be used for calibration.
2. Using recently calibrated device with liquid standard - set solid standard to an arbitrary value somewhere in the middle of adjustment to hit what I call a sweet spot.
There’s a bit of a drop off curve that occurs while using this accessory. Imagine a bell curve where the top is the best response. Adjustment from fully closed to fully open displayed on the x-axis.
I suggest adjusting the solid standard so the cover is halfway recessed into the housing and slowly adjust the unit while watching the response. You will see at some point that it will gradually get higher, level off, and drop if you adjust any farther. That Sweet Spot is where you are trying to aim so that you can get the maximum response on your unit. From that point on, use the solid standard as a check on the calibration values of the instrument. The solid standard cannot be used for calibration.
Example image below of a Red solid standard for the AquaFluor and Trilogy.
3. Using recently calibrated device with liquid standard for in vivo Chlorophyll applications - The solid secondary standard can also be used to set the instrument for in vivo applications. After calibration of the instrument with a liquid standard, adjust the solid secondary standard to match the readings displayed with a known concentration of desired algal sample. Adjust solid standard as close as possible to value. From that point on, use the solid standard as a check on the calibration values of the instrument. The solid standard cannot be used for calibration.
Using the Solid Secondary Standard for Instrument Applications
Using the Solid Secondary Standard for in vivo Chlorophyll Applications
To establish a correlation between a known chlorophyll concentration and the fluorometer reading, measure a sample containing algae and note the fluorometer reading.
Insert the Solid Standard in the Optical Module and adjust the Solid Standard to produce the same reading on the fluorometer as in step 1 by turning the Secondary Standard adjustment screw. Clockwise produces a lower signal.
Determine the chlorophyll a concentration in the sample^1 This will provide the correlation between the solid standard and the actual chlorophyll a concentration.
Now, at any time, the Solid Standard can be used to check/establish a new correlation between a known equivalent concentration and the current Trilogy reading.
1 Information on doing a chlorophyll a extraction can be found on the EPA web site at this URL: https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NERL&dirEntryId=309417
Using the Solid Secondary Standard for Dye Applications
The Solid Secondary Standard accessory can also be used to check the fluorometer’s stability for dye tracing applications.
To use the Solid Standard to establish a correlation between a known dye concentration and the fluorometer reading, measure a dye solution of known concentration, say 50 ppb, and note the Trilogy reading. Place the Solid Standard in the Optical Module, and turn the adjustment screw to produce the same displayed concentration as in step 1. Turning the secondary standard adjustment screw clockwise reduces the displayed concentration.
Comprehensive information on dye trace measurements can be found at the following Turner Designs URL: https://www.turnerdesigns.com/dye-fluorometer
What are they made of?
The outer black casing of the Solid Secondary Standard is made of delrin plastic and is very durable. The core of the Solid Secondary Standard is one of several stable fluorescent materials. It holds up to the rigors of photo-decay and as long as it is stored under ambient conditions free from dust and humidity, it will provide you with stable consistent readings for many years.
What is the best way to use it?
We usually recommend that you use the Solid Secondary Standard as a stable reference check of the instrument and not as a calibration tool. It is stable and unless adjusted, it should give stable readings. If you notice a drift in readings greater than +/-5% from the initial value recorded, then we suggest recalibrating or contacting technical support.
But can I use it to calibrate my instrument?
Given the nature of the Solid Secondary Standard and the fact that it is a plastic material and not the fluorophore of interest, we do not advise using it as the primary standard for calibrating your instrument. For applications such as dyes and turbidity, there are known and tested primary calibration standards that can be used for calibrating the instrument. However, for in vivo applications - there is no calibration standard. These samples are raw water samples and are qualitative (relative) measurements. It is important though to make sure that the instrument’s sensitivity is appropriately set for reading samples and the Solid Secondary Standard can be used as a tool to accomplish this. You can contact Technical Support if you have questions about our other instruments.