A SIMPLE METHOD FOR THE COMPARISON OF COMMERCIALLY AVAILABLE ATP HYGIENE-MONITORING SYSTEMS

The purpose of this study was to evaluate a methodology which could ea sily be used in any test laboratory in a uniform and consistent way fo r determining the sensitivity and reproducibility of results obtained with three ATP hygiene-monitoring systems. The test protocol discussed here allows such comparisons to be made, thereby establishing a metho d of benchmarking both new systems and developments of existing system s. The sensitivity of the LUMINOMETER K, PocketSwab (Charm Sciences) w as found to be between 0.4 and 4.0 nmol of ATP with poor reproducibili ty at the 40.0 nmol level (CV, 35%). The sensitivity of the IDEXX LIGH TNING system and the Biotrace UNILITE Xcel were both between 0.04 and 0.4 nmol with coefficients of variation (CVs) of between 9% at 0.04 nm ol and 10% at 0.4 nmol for the IDEXX system and 17% at 0.04 nmol and 2 1% at 0.4 nmol for the Biotrace system. The three systems were tested with a range of dilutions of different food residues: orange juice, ra w milk, and ground beef slurry. All three test systems allowed detecti on of orange juice and raw milk at dilutions of 1:1,000, although the CV of results from the Charm system (54 and 74% respectively) was poor at this dilution for both residues. The sensitivity of the test syste ms was poorer for ground beef slurry than it was for orange juice and raw milk. Both the Biotrace and IDEXX systems were able to detect a 1: 100 dilution of beef slurry (with CVs of 17 and 10% respectively), whi lst at this dilution results from the Charm system had a CV of 55%. It was possible by using the method described in this paper to rank in o rder of sensitivity and reproducibility the three single-shot ATP hygi ene-monitoring systems investigated, with the IDEXX LIGHTNING being th e best, followed by the Biotrace UNILITE Xcel, and then the Charm LUMI NOMETER K, PocketSwab.