Compare the same product and form
Check that the records refer to the same ingredient, form and grade. Similar names can describe different products, so settle product identity before comparing numerical values.
Keep the method beside the result
A useful comparison includes the parameter, value or range, unit and method. Ask for clarification when information is missing rather than assuming different figures are equivalent.
Separate specification from batch result
A specification describes the agreed product requirements. A batch certificate records information for a particular batch. Keep the batch identification and date with the document.