Performance Evaluation Test for Enzymatic Cleaners

TEST RESULTS

(Leading Competitors)

(media: photographic film)

Introduction:

 

Enzyme cleaners for medical instruments are widely accepted by Central Sterile/Supply (CS) professionals. Blood is part protein and enzyme cleaners readily attack blood (hydrolysis) at protein reactive sites. Consequently, the concept of removing blood via enzymatic cleaning action is popular among CS professionals.

 

However, numerous competitive enzyme cleaners make it difficult for the CS professional to choose which manufacturer's enzyme product to use. Furthermore, they are being marketed in different forms such as concentrated blocks and "super concentrated liquids."

 

These "super concentrates" are desirable as they eliminate the heavy transport of drums and are cost effective with respect to shipping. How does CS make a choice? Is it based on price, convenience, cleaning performance, or all of them?

However, numerous competitive enzyme cleaners make it difficult for the CS professional to choose which manufacturer's enzyme product to use. Furthermore, they are being marketed in different forms such as concentrated blocks and "super concentrated liquids."

 

These "super concentrates" are desirable as they eliminate the heavy transport of drums and are cost effective with respect to shipping. How does CS make a choice? Is it based on price, convenience, cleaning performance, or all of them?

 

Perhaps a good starting place is to determine the cleaning performance with respect to enzymatic activity. Once the cleaning performance is known, it is much easier to select a product based on the other attributes. Here is a test that reveals the relative cleaning performance of any enzyme cleaner with respect to enzymatic activity.

Photographic Film Method

Why use photographic film to evaluate the relative performance of enzyme cleaners?

 

Blood is approximately 92% water, 0.8% salts, 0.6% lipids, 0.1% sugars, and 6-8% carious proteins. A key component of photographic film is gelatin.

 

Gelatin carries out several functions in photographic film. More importantly for this test, gelatin is a pure protein originating from collagen.

 

Thus, test employs the gelatin layer on photographic film as a protein substrate. Moreover, the gelatin layer is light sensitive and hardens after exposure to light.

Blood also hardens via a process called coagulation.

 

Enzymes attack the hard protein test substrate at a rate relative to their strength.

 

Side-by-side comparisons with the test provide useful information for evaluation the performance of enzyme cleaners.

 

The enzyme cleaner that produces the fastest results is stronger and more effective.

 

Accordingly, the test empowers CS professionals to make educated purchasing decisions about enzyme cleaners.

 

If performed correctly, the results are repeatable to a high degree of certainty.

Certainly,  a seemingly good argument opposing the filmstrip might be that the protein film substrate is not similar to the protein component of blood.  In addition, the lipid and sugar components are not available.

This is true;  however,  it is very important in consideration that protein comprises approximately over 80% of the non-aqueous component of blood.

TESTING  PREP

Instruments & Materials:

 

Constant Temperature Water bath

(Fisher ISOtemp Model 205)

(control +/- 0.1 0C/F, stability +/- 0.5 0C/F)

Protein Film Test Strips (Ilford Pan F B&W film)

 

Adjustable Pipettor

(Rainin Pipetman Model P-1000)

(0.00-1 ml down to 0.002 ml increments)

25ml Plastic Vials w/snap cap

Enzymatic Cleaner Samples

Thermometer (Fluke Model 51 II, +/- 0.10 F or C)

TESTING  PROCEDURE

Test Procedure:

25ml plastic vials are filled to the rim with water to the approximate test temperature and covered with a plastic snap cap.

The vials are placed in the constant temperature bath.

The constant temperature bath is adjusted to the test temperature and allowed to reach equilibrium to set temperature for at least 1 hour.

For each sample, one vial is removed from the bath and the snap cap removed.

The pipettor transfer volume is adjusted according to the dilution label claim for each enzymatic cleaner.

For example, the pipette is adjusted to deliver 0.195ml (to the 25ml vial) of an enzyme cleaner with a label claim of 1fl.oz/gallon dilution and 0.098 ml for ½ fl.oz/gallon.

The test sample is quickly transferred into the plastic vial with the pipettor.

The snap cap is removed again and protein test strip is placed in the vial with the coated side (protein side) angled downward.

The start time is recorded when the strip is placed in the vial.

The vial is immediately returned to the constant temperature bath. The protein strips are observed for coating removal.

 The test is complete when half of the protein coating is removed from the test strip.

This is easily determined as the strip changes from opaque to clear.

At test completion, the time is recorded as the end time.

The end time is subtracted from the start time and the difference is the total time for protein removal.

Tests are conducted in triplicates, results averaged, and standard deviation is calculated.

The enzymatic cleaner with the lowest total time is more effective at removing protein.

However, if further confirmation is required it can be obtained with a TOSI test, which correlates quite well with the test above.

 

The TOSI test strip is artificial blood, formulated closely to actual blood with all of the components of blood.

 

The only disadvantage with the TOSI is time frame as it takes an hour to get results as opposed to 8-12 minutes for the filmstrip test.

TESTING  RESULTS

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