Quantitative titration is a form of chemical analysis where information about an unknown sample is collected through a controlled reaction with a known sample. A common technique is acid-base titration, but chemists can also use redox reactions and other phenomena, depending on what they are analyzing. Labs are typically used for this analysis, to provide access to the right equipment and offer a high level of control. It is often taught in chemistry classes to familiarize students with the basics and provide information about techniques in analytical chemistry.
In this procedure, the chemist takes a sample and mounts it in a flask or beaker, carefully measuring the volume. Another sample of known characteristics is added drop by drop until a reaction occurs and reaches its endpoint. There are a number of ways to measure this. They can include using a chemical agent that changes color, a pH meter, or another device to collect other information on the characteristics of the mixture. At the endpoint, the chemist can record how much of the known solution was necessary to trigger the reaction, and use this in a formula.
The goal with quantitative titration is to reach the equivalence point, marking the moment at which enough titrant is present to neutralize the sample or trigger a reaction. A sudden change should occur in the solution when this point is reached, and this can be measured with scientific equipment. In an automated quantitative titration, the computer can perform the calculations needed to return information about the unknown sample. In other cases, researchers can perform their own math, based on the concentration of the known sample and the volume needed to trigger a reaction.
Some methods of quantitative titration are more accurate than others, and the test may be repeated to confirm results. This kind of testing can be used for activities ranging from pathology to analysis of pollutants in the water supply. Automation is common in large labs, which may have equipment to handle the process of measuring, carefully delivering the titrant, and recording reactions. This equipment needs to be periodically calibrated to confirm it is working properly and check for contamination. Leftover titrant, for example, can affect the results of the next test.
Understanding this process can be important for chemists, even if they rely on automated equipment to do it. They may need to repeat a test by hand for various reasons, or could need titration skills to calibrate equipment correctly. Lab technicians may perform quantitative titration testing regularly.