The Periodic "Lecture" About Validation

The Point of this Column is to remind you of what you already know. If you read A2C2 Magazine (soon to be Controlled Environments), technology is important to you. If you follow this column, the quality of cleaning that you produce using that technology must be of value to your enterprise. If your business is pharmaceuticals, you assume validation as a part of critical cleaning. So then, are you using a validation strategy? Do you validate the performance of your cleaning system? Do you do an independent check of the cleanliness data that you normally generate?
One Reason To Do Validation
This exercise is an insurance policy. Users conduct validation to prove that their normal cleaning test is currently valid (hasn't been “fooled”). But, because validation represents additional work, it isn't justified for every operation. Usually, when a cleaning test is “fooled”, unexpected types of contamination are involved. Table 1 lists some examples.
A Second Reason To Do Validation
A frustrating situation, in which validation is essential, occurs when there is no flaw in the cleaning test. Yet performance in the next step of use fails due to a cause unrelated to the cleanliness of the parts. Often, the defect is incorrectly attributed to the cleaning process. Effort is wasted in troubleshooting a process which is performing flawlessly while the true cause of failure remains undetected.
What is Not Validation
A quotation attributed to philosopher George Santayana is “fanaticism is the practice of redoubling your efforts when you have forgotten your aim.” Validation does not mean that the normal test should be rerun many times under increased scrutiny.
More, of similar data, adds no new insight. More eyes looking in the wrong direction won't see approaching disaster. More thought with the same point of view won't produce inspiration. One validates a result by examining it from another point of view. This means something different must be done.

An Overall Approach Toward Validation
I often recommend a “total cleanliness” approach to validation of cleanliness tests.
Others call this approach “brute force.” Instead of measuring NVR, TOC, using an OSEE instrument, or counting particles, do all of the following:

• Boil a part in a suitable solvent(s) to extract everything which contaminates its surface
• Heat another part to a suitable temperature to vaporize everything which contaminates its surface.
• Clean another part in the normal manner, and weigh it again.

In each case: (1) weigh the part before and after, and (2) calculate the weight of soil removed. Then compare the total weight of contamination removed by “fire and water” with the weight of contamination removed by the cleaning process.
A Specific Approach Toward Validation
Consider an approach toward validation focused on the nature of the cleaning test under scrutiny. Measure the parameter being measured in the normal cleaning test using another approach sensitive to the same parameter.
An excellent way to do this is to use ASTM standards as validation tests. Good ones are: (1) ASTM E21.05, “Standard Method for Measurement of Nonvolatile Residue (NVR) on Surfaces,” (2) D903-98(2004) Standard Test Method for Peel or Stripping Strength of Adhesive Bonds for particulates and surface films.
Timing
Validation by another cleaning test should substitute for the normal cleaning test.
Depending upon results and required certainty, the validation test might replace the normal test every 5% to 20% of cleanliness tests.
Summary
While validation of cleanliness testing is not justified for every cleaning operation, considering use of it for every operation is justified.
John Durkee is an independent consultant specializing in critical cleaning for contamination control. Contact him at PO Box 847, Hunt, TX 78024 or 122 Ridge Rd. West, Hunt, TX 78024; 830-238-7610; Fax 612-677-3170; or jdurkee@precisioncleaning.com