What are the recommended verification and calibration steps for a TL23 that has had IQ/OQ performed on it to enable the use of 11 mm vials?

Document ID

Document ID TE11006

Published Date

Published Date 03/26/2019
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Question
What are the recommended verification and calibration steps for a TL23 that has had IQ/OQ performed on it to enable the use of 11 mm vials?
Summary
Verification and calibration steps for a TL23 using the 11 mm application.
Answer
A TL23 that has had IQ/OQ performed to enable the use of 11 mm vials has two calibration curves. 

A primary calibration curve (relating detector response to NTU of standards) is performed using 1" sealed vials.

Then there is a secondary calibration which is performed for the 11 mm application which exists on the instrument as a user program. This secondary calibration relates the NTU measurement result from the reading taken on standards in 11 mm vials from primary calibration (which was performed using the 1" sealed vials) to an NTU value of the standards in the 11 mm vials.
 
After the IQ/OQ has been performed and the 11 mm user program created, customers have the option to take a sample reading in the normal measurement mode using a standard 1" cell which would use only the primary calibration. Or to use the user program to take a sample reading using an 11 mm vial. This result essentially uses the primary calibration to get a false result, then uses the secondary calibration to convert the false result to a correct result.
 
What would be recommended is to perform regular calibration verification checks using a primary standard(s) in the 11 mm vials on the user program. If this check passes then no additional action would be required. The frequency that this standard check is performed and at what value would be determined by the customer or their regulator. If this calibration verification fails (reads outside of user or regulator set tolerances) then additional steps would be taken. 

The first step would be cell cleaning (See: 
What is the procedure for cleaning sample cells?), alignment verification and cell indexing, and then replicated on a new lot of standard. If the calibration verification fails again after taking these steps, then perform a new primary calibration using the sealed 1" standards following the instructions form the user manual.

This will generally be all that would be needed to resolve issues. It is generally not recommended to make any changes or adjustments to the User Program (secondary calibration).

If after troubleshooting and performing this primary calibration the calibration verification checks still fail on the user program then a new user program can be created. The instructions to perform this calibration were included in the IQ/OQ documentation that was provided when the service was performed. A copy of this procedure can be made available for customers that have had the IQ/OQ service performed. If needed please contact Hach Tech Support using the Ask a Question Form.
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