Standardization and Calibration in Instrumental Analysis
Introduction
Standardization and calibration are fundamental concepts in instrumental analysis. They are used to ensure the accuracy and reliability of the analytical results obtained from an instrument.
Standardization is the process of determining the concentration of a known substance (the standard) using an analytical instrument. The standard is used to calibrate the instrument so that it can accurately measure the concentration of unknown samples.
Calibration is the process of adjusting the instrument to give accurate results for a specific analyte. This is done by measuring the response of the instrument to a series of known concentrations of the analyte and then plotting the results on a graph. The graph can then be used to determine the concentration of the analyte in an unknown sample.
Basic Concepts
The following are some basic concepts related to standardization and calibration:
- Accuracy: The closeness of the measured value to the true value.
- Precision: The closeness of repeated measurements to each other.
- Calibration curve: A plot of the instrument response to a series of known concentrations of the analyte.
- Standard: A substance of known concentration that is used to calibrate an instrument.
- Unknown: A sample of unknown concentration that is analyzed using an instrument.
Equipment and Techniques
A variety of equipment and techniques can be used for standardization and calibration in instrumental analysis. The most common methods include:
- Volumetric titration: A method in which a known volume of a reagent is added to a solution of the analyte until a reaction is complete. The concentration of the analyte can then be calculated from the volume of reagent used.
- Gravimetric analysis: A method in which the analyte is precipitated from a solution and then weighed. The concentration of the analyte can then be calculated from the weight of the precipitate.
- Spectrophotometry: A method in which the absorbance of light by a solution is measured. The concentration of the analyte can then be calculated from the absorbance using a calibration curve.
- Chromatography: A method in which the components of a mixture are separated based on their different physical or chemical properties. The concentration of the analyte can then be calculated from the area of the peak on the chromatogram.
Types of Experiments
There are two main types of experiments that can be performed for standardization and calibration:
- External standardization: In this type of experiment, a standard is used to calibrate the instrument. The standard is not added to the unknown sample.
- Internal standardization: In this type of experiment, a standard is added to the unknown sample before the analysis. The standard is used to correct for variations in the instrument response.
Data Analysis
The data from standardization and calibration experiments can be analyzed using a variety of methods. The most common method is to use a linear regression analysis. Linear regression analysis is a statistical method that can be used to determine the slope and intercept of a straight line. The slope and intercept of the line can then be used to calculate the concentration of the analyte in an unknown sample.
Applications
Standardization and calibration are used in a wide variety of applications in instrumental analysis, including:
- Environmental analysis
- Food analysis
- Pharmaceutical analysis
- Clinical analysis
Conclusion
Standardization and calibration are essential for ensuring the accuracy and reliability of analytical results obtained from an instrument. By following the steps outlined in this guide, you can ensure that your instruments are properly calibrated and that your results are accurate.