We are a flexible packaging manufacturer and make labels for products. We are trying to get SQF certified for the first time this year, so I need a little help in the calibration topic. We use pH meters to test the pH of the inks that we use to print on our film and labels. We have pH testing kits that are provided by the same company that sells the meters to us. Would this be considered internal calibration or would this suffice as an approved method of calibration which would exempt us from outsourcing it?