Final answer:
LC/MS/MS is the most cost effective, reliable, and widely used drug testing procedure.
Step-by-step explanation:
The most cost effective, reliable, and widely used drug testing procedure is LC/MS/MS (Liquid Chromatography-Mass Spectrometry/Mass Spectrometry). LC/MS/MS combines the analytical techniques of liquid chromatography and mass spectrometry to accurately identify and measure drug compounds and metabolites in biological samples. It offers high sensitivity, specificity, and throughput, making it the method of choice for drug testing in clinical and research settings.