A method of chemical analysis whereby an unknown amount of an element or compound is made to react with an exactly measured amount of reagent of known composition, leading to the completion or characteristic end point of a well known stoichiometric chemical reaction. Titration methods are designated according to the mode of detection of the end point, e.g., potentiometric and spectrophotometric titration. The Safeguards Analytical Laboratory uses potentiometric titration for the determination of U and Pu content in milligram to gram size samples of non-irradiated nuclear materials