Titration, Kern titer or titrametry is a common laboratory method in analytical chemistry that quantitatively determines the unknown concentration of an analyte. This measurement and determination of the unknown concentration of an analyte or an unknown solution is done by different analyzes and methods, which we will introduce in the following. Since volume measurement is very important in the titration process, in many cases we use the term volumetric analysis method instead of titration.

Preparation and titration

To perform the titration process and determine the concentration of the unknown analyte, we first need titration solutions. Solutions that have a known concentration and are added to determine the concentration of the analyte. Titration solutions known as titrant, standard solution and reagent are poured into a burette at the beginning of the experiment and titration, and then added drop by drop to the solution with unknown concentration (analyte) which is poured into an Erlenmeyer flask. be. The process of adding the titration solution (titrant) to the unknown solution continues until the color of the detector does not change. The detector can be a substance such as phenolphthalein, which is used under the burette, and the moment it changes color is the end point of the titration.

Types of titration methods

There are different methods in the titration process and for titration that can be used depending on the type of analyte.

• Direct titration
• Reverse titration or back titration
• Indirect titration or substitution titration are among the most widely used titration methods.

Types of titration

Titration has different types based on the type of reaction involved and the purpose of doing it, the most important and most used of which are:

• Acid-base titration: in which a basic or acidic titrant reacts with an analyte that is either a base or an acid. In fact, this reaction is the neutralization reaction of acid and base.

Acid-base titrations include cases of weak acid and base, weak acid with strong base, weak base with strong acid, and strong acid and base.

• Complexometry: It is the complexation reaction of a metal with a ligand. And the introduction that is mostly used in this process is disodium ethylene diamine tetraacetate.
• Sediment titration: It is a method used to determine the concentration of elements. In this method, the product of the sedimentation reaction is sedimentation titrations including titrations with inorganic titrants and surfactants titrations.
• Oxidation-reduction (redox) titrations: that is, the process of titration is an oxidation-reduction reaction. In this type of titration, the titrant is an oxidizing or reducing substance, and usually we don’t need to add an indicator because the reagents are colored.
• Gas phase titration: in this method, we use a gas instead of nitrate and mix the reactants with a gas.
• Zeta potential titration: In this type of titration, the completion of the reaction is not determined by the indicator, but by the zeta potential!
•  Iodometry: It is a reaction in which iodine is oxidized. In iodometric titration, iodine plays the role of identifier and its titrant is usually thiosulfate.

Familiarity with titration vocabulary

Before performing titration, it is better to know its terms and get familiar with the concepts and meanings of words that we use in connection with titration methods:

• Analyte: The component in the sample that the purpose of chemical analysis is to measure quantitatively and qualitatively, such as blood concentration.
• Titrant: It is a solution that has a specific chemical formula and concentration and is added to the solution containing the analyte.
• The amount of titrant used in the titration process is recorded as a mark and it is used to determine the concentration or purity percentage of the analyte.
• Reagent: It is a colored compound whose color change is a sign to determine the end point of the titration reaction. The reagent is usually a base or a weak acid.
• Equivalent point: (Equivalent point) is the point where the molar ratios of analyte and titrant are the same. In other words, the amount of equivalents of analyte and titrant are equal. and the titrant and analyte have completely reacted together.
• Titration curve: It is a curve where the horizontal or x axis shows the volume of nitrate added from the beginning of the reaction and the vertical or y axis shows the analyte concentration in that volume.
• If we use a strong acid or base in the titration process, the vertical axis shows the pH changes.

Applications of titration

In addition to determining the concentration in chemical analysis processes, titration has other uses, some of which are as follows:

1- Determining the acidity and alkalinity of water samples
2- Determining water hardness
3- Determining total nitrogen by Kjeldahl nitrogen analysis
4- Use as volumetric methods in various industries such as food, water and sewage, mining, pharmaceutical and …

• The volumetric analysis method is one of the old and widely used methods of chemical analysis, in which the amount of substance A (sample, analyte or titrant) in a sample is based on the required volume of substance B with a certain concentration (titration solution, titration standard solution or title) is determined. While A and B have complete reaction with each other.

5- Preparation of biofuels using acid and base titration
6- Determination of oxygen in water using redox titration
7- Bending reagent and determination of excess glucose in urine
8- Use in industries such as food industry, medical diagnosis laboratories, laboratories Chemistry, mining, water and sewage industries and pharmaceuticals are other applications of titration.
9- We can also mention the determination of the concentration of viruses and bacteria in biology.