Introduction
Titration is only as reliable as the method behind it. While the chemistry drives the reaction, the method parameters guide the instrument through each step with precision and purpose. From selecting the appropriate titration mode such as MET, DET, SET or KFT, to defining start conditions, signal drift limits, waiting times, volume increments, and stop criteria, each setting plays a critical role in accuracy and reproducibility.
This article provides a practical overview of key titration method parameters, including endpoint criteria, endpoint recognition, and measuring point density, helping users understand not just what to configure, but why those choices matter for confident, reliable results.
Titration Modes
SET
Set Endpoint Titration, or SET mode, is used when the endpoint of a reaction is clearly defined. In this mode, the titrator delivers titrant until a specified target value, such as a fixed pH, potential, or conductivity, is reached. Because the endpoint is predetermined, SET titration is ideal for routine analyses where the reaction behavior is consistent and the equivalence point does not need to be calculated dynamically. This approach offers a straightforward and efficient way to achieve reliable, repeatable results when working with well-established methods.
MET
Monotonic Equivalence Titration (MET) mode is designed for slower titration reactions where the equivalence point is reached abruptly rather than through a well-defined S-shaped curve. In this mode, titrant is added in controlled increments while the instrument monitors the consistent, one-directional change in signal to identify the sudden shift that marks the equivalence point. This makes MET particularly useful for applications such as vitamin C determination and certain non-aqueous titrations, where the reaction progresses steadily and then transitions sharply at equivalence. By tracking the monotonic signal behavior, MET ensures accurate and reliable endpoint detection in systems where traditional curve evaluation may not be suitable.
DET
Dynamic Equivalence Titration (DET) mode is the most widely used titration mode and is well suited for fast, well-behaved reactions. In DET, the titrant addition rate is automatically adjusted based on the reaction’s signal change, allowing the system to add larger increments when far from the equivalence point and smaller, more precise increments as it approaches it. Because duration is prioritized, DET optimizes analysis time without sacrificing accuracy, making it an efficient and versatile choice for routine applications. Due to its adaptability and reliability, DET is considered the universal titration mode and is suitable for approximately 90% of standard titration methods.
KFT
Karl Fischer Titration (KFT) mode is specifically designed for the accurate determination of water content. Unlike other titration modes that target a broad range of analytes, KFT is optimized for the selective and quantitative reaction between water and the Karl Fischer reagent. The instrument precisely controls reagent addition and monitors the electrochemical signal to determine when all water in the sample has reacted. Suitable for both volumetric and coulometric techniques, KFT provides reliable moisture analysis across a wide range of sample types, from trace-level water determination to higher concentration measurements.
Key Method Parameters - MET & DET
Start Conditions
Signal Drift
Signal drift is a critical parameter in both MET and DET modes, as it defines the required stability of the measured value during titration. By monitoring how quickly the signal changes over time, the instrument can assess whether the reaction is progressing or approaching equilibrium. Signal drift directly influences the speed of the titration, helping regulate when titrant addition should continue or pause to allow the system to stabilize. It also serves as a criterion for method control, determining when conditions have been met to transition to the next step in the analysis or proceed toward endpoint evaluation.
Min/Max Waiting Time
Minimum and maximum waiting times in MET and DET modes define how long the titrator pauses after each addition to allow the measured signal to stabilize before proceeding. The minimum waiting time ensures that signal evaluation does not begin until a defined stabilization period has elapsed. This is particularly important for systems with slow reaction kinetics, slow sensor response times, or noticeable mixing effects between the sample solution and titrant. It effectively provides the necessary time for the measuring signal to settle before signal drift is assessed.
The maximum waiting time, on the other hand, limits how long the instrument will wait before adding the next volume increment. Once this time has elapsed, the signal is accepted regardless of whether the defined drift criterion has been fully achieved. Used in conjunction with signal drift, these parameters control the overall speed of the titration. In general, the smaller the allowed signal drift, the larger the maximum waiting time required. In a well optimized method, however, the maximum waiting time should not be reached under normal conditions.
Titration Parameters - MET
Volume Increment - MET
In MET titrations, the volume increment parameter defines the fixed amount of titrant added with each step of the analysis. Selecting the appropriate increment size is essential for balancing speed and resolution. When developing a new method, a practical starting point is 0.1 mL. As a general guideline, the increment should be approximately 1/20 of the expected equivalence point volume. For reactions that produce a steep, sharp jump at equivalence, smaller increments closer to 1/100 of the expected endpoint volume improve accuracy and resolution. For flatter, more gradual signal changes, larger increments closer to 1/10 may be appropriate to maintain efficiency without compromising endpoint detection.
Stop Conditions - MET & DET
Potentiometric Evaluation - MET & DET
Evaluation
Evaluation parameters determine how the instrument identifies and reports equivalence points during a titration. The End Point Criterion (EPC) defines the minimum requirement that must be met for an equivalence point to be recognized. If the calculated equivalence point value is smaller than the defined EPC, it will not be accepted or reported. End Point Recognition settings act as a filter for how recognized equivalence points are selected and displayed. Available options include All, Greatest, Last, Ascending, Descending, or Off, allowing the method to be tailored to the specific reaction behavior and analytical goal.
Titration Parameters - DET
Measuring Point Density - DET
In DET mode, measuring point density controls how large or small the titrant increments are during the course of the titration. The setting ranges from 0 to 9 and directly influences the resolution of the titration curve. When set to 0, the titrator delivers very small increments, resulting in a high measuring point density and greater detail around the equivalence point. Higher values increase increment size and reduce the number of measuring points collected. The default value of 4 provides a balanced approach between speed and resolution and is suitable for most routine titrations.
Minimum Increment - DET
This setting controls the volumes dispensed at the very start of a titration and in the region of the equivalence point.
Volume Increment - DET
In DET titrations, the minimum and maximum volume increments define how the titrant is delivered throughout the curve. The minimum volume increment is applied in the steep regions of the titration curve, where precise control is required to accurately capture the equivalence point. The maximum volume increment sets the upper limit for how much titrant can be added in a single step, typically when the reaction signal is changing more gradually. If the maximum increment is set too high, especially for sharply changing curves, the curve will be recorded with lower resolution, which can reduce precision. Proper adjustment of these parameters ensures both efficient titration time and accurate endpoint determination.
Additional Support
If you encounter any issues or need additional help, please submit a support ticket through Metrohm Technical Support.
For additional training on any of these topics, explore our available Metrohm Titration Training courses or learn more about our Metrohm Custom Training options.