Jump to content

  • Quick Navigation
Photo

SQF 2.4.4.2 proficiency testing - water activity

Share this

  • You cannot start a new topic
  • Please log in to reply
7 replies to this topic

matthewcc

    Grade - MIFSQN

  • IFSQN Member
  • 111 posts
  • 16 thanks
11
Good

  • United States
    United States
  • Gender:Male

Posted 02 November 2022 - 03:56 PM

Hello, I have a question that I didn't see in the forums or in the SQF GUIDANCE:

 

We are using a water activity meter to test water activity of ingredients and products.  We have been doing proficiency testing for water activity by splitting a sample and testing part in-house for water activity and sending part to a third-party laboratory and comparing the results from the two.

 

The part I don't understand is about comparing results.  For example, one dried botanical (cut & sifted, i.e., pieces about 6 mm long) has in-house and third-party water activity results of 0.60 and 0.474, respectively.  What acceptance criteria should we be using, e.g., a maximum relative standard deviation (RSD) percentage?  These results seem quite far apart, but I have a difficult time finding acceptance criteria for such proficiency testing.

 

We manufacture dietary supplements in the United States, are compliant with 21 CFR Parts 111 and 117, and have an SQF Edition 9 certification.  We have already read the SQF guidance for proficiency testing, and this type of detail is not in the guidance.

 

Thank you,
Matthew



Gelato Quality Specialist

    Grade - MIFSQN

  • IFSQN Member
  • 68 posts
  • 12 thanks
27
Excellent

  • United States
    United States

Posted 02 November 2022 - 04:41 PM

From my understanding of proficiency testing, it is up to each company to decide what the acceptance criteria should be, based on risk. 

 

Still working on becoming compliant with this part of the code, so hopefully others can share their experiences.



Charles.C

    Grade - FIFSQN

  • IFSQN Moderator
  • 20,104 posts
  • 5538 thanks
1,458
Excellent

  • Earth
    Earth
  • Gender:Male
  • Interests:SF
    TV
    Movies

Posted 02 November 2022 - 05:45 PM

 

Hello, I have a question that I didn't see in the forums or in the SQF GUIDANCE:

 

We are using a water activity meter to test water activity of ingredients and products.  We have been doing proficiency testing for water activity by splitting a sample and testing part in-house for water activity and sending part to a third-party laboratory and comparing the results from the two.

 

The part I don't understand is about comparing results.  For example, one dried botanical (cut & sifted, i.e., pieces about 6 mm long) has in-house and third-party water activity results of 0.60 and 0.474, respectively.  What acceptance criteria should we be using, e.g., a maximum relative standard deviation (RSD) percentage?  These results seem quite far apart, but I have a difficult time finding acceptance criteria for such proficiency testing.

 

We manufacture dietary supplements in the United States, are compliant with 21 CFR Parts 111 and 117, and have an SQF Edition 9 certification.  We have already read the SQF guidance for proficiency testing, and this type of detail is not in the guidance.

 

Thank you,
Matthew

 

Hi mattthew,

 

So what is the estimated +/- confidence in the results ?


Kind Regards,

 

Charles.C


matthewcc

    Grade - MIFSQN

  • IFSQN Member
  • 111 posts
  • 16 thanks
11
Good

  • United States
    United States
  • Gender:Male

Posted 03 November 2022 - 06:23 PM

Hello Charles.C, I am not sure.  The accuracy of the unit we use for testing for water activity is ±0.02 aw according to the manual.  However, that is not the only factor affecting uncertainty or confidence, which might be most clearly evident in how much variability we are seeing in replicate results for a given sample type.  I am trying to get data on replicate analyses from our lab and from the third-party lab.

 

Matthew



AJL

    Grade - MIFSQN

  • IFSQN Member
  • 197 posts
  • 5 thanks
17
Good

  • Germany
    Germany
  • Gender:Male

Posted 12 November 2022 - 05:16 PM

Is everyone measuring at the same temperature?
Was the sample treated in the same way?
Are you doing 2-3 readings on the same sample?
Are you calibrating your machine each time?
Seems like too much of a swing to me. I would expect results within 0.05 of each other....if it's the same sample.
Looking forward to hearing how it goes



Thanked by 1 Member:

Charles.C

    Grade - FIFSQN

  • IFSQN Moderator
  • 20,104 posts
  • 5538 thanks
1,458
Excellent

  • Earth
    Earth
  • Gender:Male
  • Interests:SF
    TV
    Movies

Posted 13 November 2022 - 05:43 AM

Hello Charles.C, I am not sure.  The accuracy of the unit we use for testing for water activity is ±0.02 aw according to the manual.  However, that is not the only factor affecting uncertainty or confidence, which might be most clearly evident in how much variability we are seeing in replicate results for a given sample type.  I am trying to get data on replicate analyses from our lab and from the third-party lab.

 

Matthew

Hi matthew,

 

Sorry for delay, I missed yr reply.

 

As per AJL, you should be using reference samples for calibration ?

 

Differences  can be a question of sampling or analytical variation, or both.

 

You need to do a little "blind" replicate sampling at both ends to get an idea of accuracies involved (+ ideally include a (anonymous) reference sample for ext.lab.

 

Offhand, I agree with AJL, the results look simply incompatible. My guess is non-homogeneous sample if yr calibration/Procedure is ok. Should be readily checkable though.


Kind Regards,

 

Charles.C


Thanked by 1 Member:

matthewcc

    Grade - MIFSQN

  • IFSQN Member
  • 111 posts
  • 16 thanks
11
Good

  • United States
    United States
  • Gender:Male

Posted 18 November 2022 - 10:29 PM

Thanks, I'm trying to get replicate data from our lab to see how close they are to one another.  Unfortunately, not much of an investigation was done into the differences & I am pushing for more info.



AJL

    Grade - MIFSQN

  • IFSQN Member
  • 197 posts
  • 5 thanks
17
Good

  • Germany
    Germany
  • Gender:Male

Posted 19 November 2022 - 01:12 PM


Remember it's temp dependent so the temperature you have det your chamber to is important.

Try and find some literature as well for expected valued in your product.
An external lab isn't always right
Ask to see their test method if you can.





Share this


Also tagged with one or more of these keywords: SQF, water activity, proficiency testing, acceptance criteria, statistics

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users