A differential adenosine triphosphate test method for differentiating between bacterial and fungal contamination in water-miscible metalworking fluids

• A new ATP method permits differentiation of fungal and bacterial cellular ATP (cATP).
• The differential cATP test method was field tested by four global MWF companies who tested >250 used MWF samples.
• Differential cATP results either indicated the same or more bacterial contamination than that indicated by culture test results for 91% of used MWF tested during field evaluation.
• Differential cATP results either indicated the same or more fungal contamination than that indicated by culture test results for 89% of MWF tested.
• The differential cATP test augments ASTM E2694 test results by qualitatively differentiating between fungal, bacterial and mixed bacterial & fungal contamination.

A new variation of a method for quantifying cellular adenosine triphosphate (cATP) is described. The variation permits differentiation between cATP from bacteria and cATP from fungi. This paper describes the process by which the new differential cATP method was developed and validate in both laboratory and field tests. Laboratory tests using bacteria, yeasts and filamentous fungi demonstrated that cATP observed in ≥5 μm and <5 μm size-fractions, respectively were consistently within ±10% of predicted concentrations. The field evaluation during which four participating metalworking fluid (MWF) compounders collectively tested >250 used MWF samples, confirmed that the differential protocol reliably detected fungal contamination when it was present.

Relationship between differential-cATP and culture test results in 256 used, metalworking fluid samples.Figure optionsDownload as PowerPoint slide