Copper sulfate solution is utilized in colorimetric analysis as a reference standard due to its stable and intense blue color, enabling the measurement of absorbance to determine concentrations of specific substances in solution via the Beer-Lambert law. It serves for calibration of spectrophotometers and colorimeters, particularly in assays for proteins, sugars, and other biochemical compounds. Common applications include clinical laboratories, environmental testing, pharmaceutical quality control, and educational settings to demonstrate quantitative analysis principles.