1.1 This test method provides a protocol for capturing, concentrating, and testing the adenosine triphosphate (ATP) present in a fuel system sub-sample (that is, test specimen) associated with: 1.1.1 Microorganisms and hydrophilic particles found in liquid fuels as described in Table X6.1, or 1.1.2 Microorganisms and hydrophilic particles found in mixture of fuel and associated bottom water or just associated bottom water. 1.1.3 ATP detected by this bioluminescence test can be derived from cellular ATP, extra-cellular ATP, or some combination of both. 1.1.4 Cellular and extra-cellular ATP utilized to perform ATP bioluminescence are captured and concentrated from a fuel system sample into an aqueous test specimen (that is, sub-sample) for testing. For example, for a fuel system sample that does not contain any visible fuel associated bottom water, the aqueous test specimen is the capture solution itself described in 8.2.1.1. For fuel system samples that are a mixture of fuel and associated bottom water (that is, free water), the test specimen is an aliquant of the capture solution and associated bottom water. 1.2 The ATP is measured using a patented bioluminescence enzyme assay, whereby light is generated in amounts proportional to the concentration of ATP in the sample. The light is produ