ChemPharma - Synthesis and Production
In a chemical-pharmaceutical production process, different products are brought together. All kinds of physical processes and chemical reactions take place in the synthesis reactor. The sequence, quantity and timing of dosing of a particular ingredient are very important. Proper process monitoring is called for.
Process monitoring - tracking changes in physical or chemical properties?
Every production is different. However, it often involves dissolving or precipitating solids, polymerisation, solvent swaps, mixing, dilution, etc. All these production steps can be monitored by various measurement and analysis techniques. Usually, a combination of different techniques is needed to get a complete picture of the entire process.
With a spectrophotometer you measure the absorption of different wavelengths over a spectrum, from UV over VIS to NIR. Each molecule absorbs different wavelengths, giving you the so-called “fingerprint”. Through constant monitoring, you know exactly when and how much product is being synthesised or broken down, and you can determine yield and profitability or make adjustments if too many by-products are created.
An inline refractometer measures the concentration of all products dissolved in water or an organic solvent. A particular product dissolves better in one solvent than in another. That's why solvent swaps are carried out that can be perfectly controlled or monitored by a refractometer.
An inline measurement of the refractive index can also be used to monitor a recipe. The addition of a particular product changes the refractive index of the solution. You get a specific pattern throughout the process. Deviations from the pattern indicate too much or too little product dosage or the addition of an incorrect substance.
Many chemical reactions are only able to proceed at a certain pH value. If the pH is incorrect, nothing will happen or the efficiency of the reaction will be poor. pH measurement ensures the right process conditions. The same applies to the redox potential (ORP).
Reactions are often accompanied by colour change. A photometer measures the absorption of one or several wavelengths and can thus determine how much of which product is created or consumed.
It’s not always liquids that are mixed together. Very often, solids (powder or crystals) are added. A turbidity meter measures whether solids are dissolved or remain in suspension.