6 replies to this topic

[vivian87]

As per QC requirement, we are running duplicate analysis at 10% frequency.

 

How to know which result to report if both sets of results are different? We cant report the average results.

 

Shall we report the one with highest number?

 

Thanks in advance.

[kconf]

Are you talking about MPN vs CFU for ec/coli? 

[vivian87]

Are you talking about MPN vs CFU for ec/coli? 

 

MPN for coliform and e.coli

[kconf]

Ok, MPN is relatively more accurate than plating (cfu) method. It can detect microbes at lower levels unlike cfu. 

For product testing I'd go by MPN if had to choose between the two, for environmental cfu is fine.

I feel duplicate analysis is a waste of money. 

[vivian87]

Ok, MPN is relatively more accurate than plating (cfu) method. It can detect microbes at lower levels unlike cfu. 

For product testing I'd go by MPN if had to choose between the two, for environmental cfu is fine.

I feel duplicate analysis is a waste of money. 

 

We need to do duplicate analysis at 10% frequency as part of our QC...as per stated in the APHA.

Or do you have any other suggestion for other QC to replace duplicate analysis? 

is a waste of money, true. but no choice, need to compliance to ISO 17025.

[Bo16]

Since micro is never an exact science... All results are valid.  I would not average retests.  Write a SOP and defines what difference is acceptable and why and what to do if the difference is higher.  Also, all results must be within product specification on their own, not in specification by averaging.  

[kconf]

Both methods are valid. FDA does not have such requirement. Your results should not vary drastically, just stay within your spec.