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PAA test strips not matching titration results

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Best Answer , 12 February 2024 - 07:46 PM

To your first question - you could decrease how often you test if you have data to back it up. We go based upon pounds of product ran rather than hours. 

We did this based upon a 90 day validation study of our process. A 90 day validation study is a lot of work at the beginning but then makes the process easier. You are able to reduce the amount of testing and justify it when you have a federal inspection. 

 

To your second question - we've never tested PAA using titration strips only using the kit. So unsure. 


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LGeorge74

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Posted 12 February 2024 - 05:42 PM

We are a small RTE fresh-cut fruit and veg operation and use PAA in our product prewash as well as a post cutting rinse.  We use it in appropriate PPMs per guidance from our chemical company and other accepted scientific sources on a number of different commodities, mostly between the range of 40 - 80 ppm,.

 

We test our wash and rinse water hourly and have resorted to only doing titration tests due to having problems with our test strips.  They read consistently higher than the titration results.  We have tried multiple brands and have set up tests using PAA dilution ratios as a control and then compare the results to titration results.

 

I realize test strips are an approximation seeing that you are relying upon someone to interpret a color chart, but we are consistently getting reading that are nowhere close to the titration results.  One brand reads approx 30 ppm higher, another 60 ppm higher, etc..  We see consistency within brands but no consistency between brands.

 

It is frustrating as we are basing everything else we do off of scientific data and test results but then are experiencing this uncertainty with the test strips.  Our chemical supplier has said that most of his customers just do a test to make sure that the PAA is present in some capacity, but that is hard to imagine.

 

Two questions. One, is doing hourly titration tests an overkill if we don't see much of a PPM change unless running a few certain commodities.  Two, has anyone ran into this sort of thing with the PAA test strips before.



Scampi

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Posted 12 February 2024 - 06:31 PM

Test strips of any kind are always less accurate that titration. 

 

Frequency would depend on:

 

How much product AND new treated water do you go through in an hour

 

how reliable is your dosing system

 

Do you have another potable rinse 

 

PAA should off gas quickly into water and vinegar so you're risk here is quite low


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kfromNE

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Posted 12 February 2024 - 07:46 PM   Best Answer

To your first question - you could decrease how often you test if you have data to back it up. We go based upon pounds of product ran rather than hours. 

We did this based upon a 90 day validation study of our process. A 90 day validation study is a lot of work at the beginning but then makes the process easier. You are able to reduce the amount of testing and justify it when you have a federal inspection. 

 

To your second question - we've never tested PAA using titration strips only using the kit. So unsure. 



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veruca

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Posted 15 February 2024 - 05:32 PM

We're fresh cut produce as well. We find the titration to be our numbered reading that we base any adjustments off of. We titrate hourly just based on the number of products we run and capacity. We do the test strips on the 30 minute mark because Primus audit scheme requires a check every 30 minutes regardless of data. We mark the test strip check as a pass/fail. So if you are under PrimusGFS- check for that requirement. 

 

The test strips are remarkably sensitve to exposure time and technique. The other verfication- does your chemical company partner with you and verify your titration readings periodically as a benchmark? We have our team "calibrated" quarterly against the chem rep to make sure we're all still reapeatable. The storage temp of test kits can alter readings also. We had a rep get a "hot" kit our of his car to check us and found his readings different than ours. it wasn't significant but with a small application window it may be enough. There may be a technique in the titration that could alter your titration but my money is more on the test strip being dicey to get right and read. 

 

If your PAA label allows for a higher limit in this application, then I could see the test strip pass/fail option being more accepted for documentation purposes. 

 

veruca



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