Could I ask for a bit of input into an issue I've been investigating lately?
I received 2 batches of CaCl2 Dihydrate from a supplier with a CoA result expected below and above my specification (5.4 and 6.3 respectively) (my specification is 5.5-6.0)
On testing at a 10% w/v solution at 23 degrees =/- 2 degrees (our specification) we generated results of (6.37 and 6.70 respectively).
Following an initial RCA I came to conclusion of a genuine OOS result being generated.
Further testing was conducted since the supplier tested at a 5% w/v concentration, as well as a repeat at 10% w/v at 23 degrees C +/- 2 degrees.
Results were: 5% - (5.77 / 5.99)
10% - (5.91 / 6.31)
The pH meter was calibrated and passed before every measurement and intermediate checked afterwards, the same pH meter was used to test other products by various other analysts on all days - of which no atypical results were generated.
A brand new pH probe was also installed and used after the initial OOS result.
on a visual comparison both batches look relatively uniformed with regard to particle size.
I'm thinking that the batches might have been taken from the "end of the pot" on the supplier's side leading to a lack of homogeneity?
These results seem to be coming out of a random number generator - this issue aside the results initially taken were also nowhere near the CoA (and the difference between batches was fairly large).
Any input would be most appriciated!
Thanks in advance!