Doyle W. Stephens David J. Shultz 1980 An inexpensive delay timer was designed to modify a commercially available ATP photometer which allows a disposable tip pipette to be used for injecting either enzyme or sample into the reaction cuvette. The disposable tip pipette is as precise and accurate as a fixed-needle syringe but eliminates the problem of sample contamination and decreases analytical time. (USGS) application/pdf 10.3133/ofr801194 en U.S. Geological Survey Rapid and precise determination of ATP using a modified photometer reports