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The difference between a “monitor” and an “analyzer”

Q: When measuring a process step, what is the difference between a "monitor" and an "analyzer?"

A:

Emil Ciurczak responds:

Normally a "monitor" is continuously measuring (or “monitoring”) some physical/chemical parameter. The output is relative to a previous run or standard level of voltage, resistance, absorbance, etc. In other words, we might have an upper control limit or lower control limit without units. Another way is chemometrically using Mahalanobis distances, Principal Components, or Conformity Index to ascertain that the current material is “similar to” or "dissimilar from" previous acceptable batches.

An “analyzer” uses a quantitative algorithm and the output is closer to "99.6% of label." It will be a "formal" analytical result and need as much validation as a QC method.

In most cases, a monitor will not trigger the need for 21 CFR Part 11 to be employed. An analytical output will.