Preparing primary Rhodamine WT standards for fluorometry can be troublesome as well as time consuming. Handling of concentrated dye solutions should be minimized since they stain and are difficult to remove. Since Rhodamine WT is temperature sensitive and photosensitive, stability of the final standard is always a concern. Solid Secondary standards circumvent some of these concerns, especially in field applications where there is little time and few resources to prepare new standards or examine the stability of existing standards. When conducting dye studies, solid secondary standards provide a simple, stable, and less expensive alternative to multiple calibrations with several dilutions of a primary standard. Once the instrument is calibrated with a primary Rhodamine WT standard, the solid secondary standard can be used effectively for calibration, with only occasional verification of results with a primary standard. Thus, solid secondary standards make it simple to check for instrument drift and to perform routine recalibrations. Turner Designs now offers solid secondary standards, sealed in a holder, that fit directly into the 13 mm adaptor of the 10-AU or Model 10 Fluorometer. Each holder contains two ready-to-use fluorometric standard concentrations: one high-level and one low-level concentration equivalent.

Features of the Solid Secondary Standards
10-AU: P/N 10-AU-904

• Saves Time and Money. Preparation of primary standards are capital and labor intensive. Purchasing premade primary standards each time you calibrate is extremely costly. Traditional secondary standards are often used to decrease costs, but can require special handling and preparation time. Our solid secondary standards are stable and ready to use upon arrival with no preparation needed.
• No Special Storage Conditions. The solid secondary standards can be stored in a drawer or on the benchtop. They are not photosensitive or temperature sensitive. Degradation is minimal after years of environmental exposure.
• Guaranteed. The solid secondary standards are guaranteed for two years after arrival in your lab.

Calibrating with the Solid Secondary Rhodamine WT Standards:

1. Calibrate your fluorometer with a known Rhodamine WT standard.
2. Insert the 13 mm adaptor if you have not already done so.
3. Insert the solid secondary Rhodamine WT standard and record the reading for low concentration. Rotate your standard and record the reading for high concentration. Record these numbers on the log sheet included with your standard.
4. Future instrument calibrations or checks may be performed by using the solid secondary standards and values obtained in step 3.

Total Rhodamine WT Concentration Specifications:

High Fluorometric Standard: Approximately 200 ppb

Low Fluorometric Standard: Approximately 20 ppb