The University of Massachusetts Lowell (UMass Lowell) Toxics Use Reduction Institute’s (TURI) Laboratory is performing gravimetric analysis as part of the IEHA’s High Performance Cleaning Product (HPCP) testing programme to verify the cleaning performance of environmentally preferable products and equipment. The technology available for measuring comparative soil removal continues to advance, and IEHA has incorporated these testing processes in its HPCP programme.
Measurement is performed before and after cleaning using 2” x 4” rectangular test coupons or panels, flat sheets matched to a particular surface’s materials of construction, for example, stainless steel, ceramic or glass. Coupons are number-etched for identification. Coupon testing is performed in triplicate (minimally) to determine cleaning effectiveness. Testing consists of:
- Initial weighing of pre-cleaned coupons by means of an analytical balance (gram weight)
- Applying the appropriate contaminant (oil, grease or soil) to the surface of the coupons with a hand-held swab in a highly consistent manner
- Re-weighing the artificially-contaminated coupons under the same conditions as (1)
- Performing the actual cleaning trial (entails the primary elements of cleaning such as time, agitation, concentration and temperature, collectively known as TACT)
- Final and third weighing of cleaned coupons under the same conditions as (1)
Gravimetric analysis using precisely calibrated analytical scales helps to determine by weight the percentage of soil that was removed from surfaces, and eliminates human error and guesswork. These devices allow the user to determine soil removal with a high level of accuracy.