Index of Refraction
Nov 4, In the beginning, I tried to establish a relationship between a solution's index of refraction and its density experimentally (i.e. making a table of. Sep 1, The dependence of refractive index on the concentration and . Fluorescence correlation spectroscopy experiments to quantify free diffusion. Apr 14, Index of refraction monitors, says Entegris, can control There are many methods used to measure concentration including refractive index, conductivity, by taking a sample and using offline tests including: electrophoresis.
IoR has been shown experimentally to be a significant if not superior means of detection and identification of process fluids as compared to inline quality control methods like conductivity, pH, and osmolality. Unlike nonspecific indirect methods, IoR can be used to both positively identify and display concentration measurements.
Furthermore, previous experiments have shown the usefulness of IoR as a quality control metric for buffers and media components. Positive identification and quantification of biopharmaceuticals and other protein-based products during manufacturing are often performed by taking a sample and using offline tests including: The newer IoR technology works well for highly ionic solutions and nonionic chemistries.
This tutorial outlines applications for the IoR method as PAT for monitoring and control of biopharmaceutical purification processes. Included are examples of key process steps where the technology can be used.
Homework Help: Finding Concentration Using Index of Refraction
Entegris IoR Concentration Monitors Cell Removal and Clarification The process of removing cells and cellular debris from a harvested culture prior to purification is typically performed using depth filtration, tangential flow filtration, centrifugation, or a combination of methods.
Filters are often placed downstream in order to capture any material that escapes the separation method. IoR can also identify buffers for diafiltration and recovery of product, while detecting even small concentrations of cells or cellular debris breakthrough.
Due to this identification and detection, processes can be designed to bypass cellular breakthrough filters until, and only if, they are needed. This can lead to a cost savings.
During MF and depth filtration, IoR monitors optimize the diafiltration process by detecting when a product is below its target concentration. Utilizing real-time IoR monitors enhances these processes by reducing process time and product dilution.
Using the handwheel on the right side of the instrument, adjust this border until it is in the center of the field of vision.
Concentration Measurement with Refractive Index
If the view appears dark, the adjustment should be in the counterclockwise direction; if the view appears bright, the adjustment should be in the clockwise direction. The actual border line may be strongly colored. To make the borderline as sharp as possible and to minimize the amount of color that is surrounding the border, adjust the position of the dial that is located underneath the eyepiece.
Bring the borderline directly on the crosshairs of the viewfinder using the control wheels on the right side of the instrument. The small wheel should be used for coarse adjustment; the larger wheel utilized for more fine adjustments. The final adjustment should be in the clockwise direction. Press the switch on the front left-hand side of the refractometer.
The digital display will show the refractive index to the fourth decimal place.
- Concentration Measurement with Refractive Index
Many industries use refractometer-based methods in quality control applications. In most cases the refractive index is linearly or nearly linearly related to the percentage of dissolved solids in a solution Figure 2. By comparing the value of the refractive index of a solution to that of a standard curve the concentration of solute can be determined with good accuracy.
A much more detailed standard curve for the relationship between the refractive index and the percentage of sucrose is available as a PDF file.
Structural Information The refractive index does not provide detailed information about a molecule's structure, and it is not usually used for this purpose since spectroscopic techniques are much more powerful at revealing details of molecular structure.
One structural factor that influences the refractive index of a sample is its polarizability. Substances containing more polarizable "soft" groups e.