What is an internal standard and why is it used?

An internal standard is a substance added in a constant amount to samples, blanks, and calibration standards in analytical chemistry to improve the accuracy and precision of measurements. It compensates for variations in sample preparation, instrument response, and environmental factors, helping to minimize errors. By comparing the response of the analyte to that of the internal standard, analysts can achieve more reliable quantification of the target compound in complex mixtures. This technique is commonly used in methods such as chromatography and mass spectrometry.