A UV-Vis spectrophotometer detects counterfeit products through a systematic analytical process that includes sample preparation, absorbance spectrum measurement, comparison with a reference sample, and evaluation of differences in peak position, absorbance intensity, and overall spectral profile. When two products differ in chemical composition, their UV-Vis spectra will almost always show measurable differences.
UV-Vis spectrophotometers are widely used in the analysis of food, pharmaceuticals, cosmetics, and chemical products.
Step 1 – Prepare the Sample for Analysis
Proper sample preparation is essential to obtain reliable results.
Collect a representative sample.
Dissolve the sample using the appropriate solvent.
Filter the solution if suspended particles or sediment are present.
Dilute the sample to the required concentration.
Step 2 – Measure the Absorbance Spectrum of the Suspected Sample
The UV-Vis spectrophotometer scans the sample to obtain its absorbance spectrum.
The procedure typically includes:
Placing the sample into a cuvette.
Selecting the wavelength range (for example, 190–800 nm).
Scanning the entire spectrum.
Recording the absorbance curve.
Step 3 – Measure an Authentic Sample to Create a Reference Spectrum
The spectrophotometer compares the test sample with an authentic product or a reference spectrum stored in a spectral library.
Many manufacturers build spectral libraries by measuring all qualified raw materials and approved finished products. This practice significantly reduces the risk of introducing substandard or counterfeit materials into the production process and provides a reliable benchmark for future quality inspections.
Labomed UV-Vis Spectrophotometer
Step 4 – Overlay the Two Spectra to Identify Differences
The operator compares the spectrum of the test sample with the reference spectrum on the display of UV Vis spectrophotometer and looks for signs of inconsistency.
Absorption peaks appear at different wavelengths
→ The chemical composition may have changed.
Lower absorbance intensity
→ The active ingredient may have been diluted or reduced.
Additional absorption peaks appear
→ Different additives or impurities may be present.
Changes in the overall spectral profile
→ The formulation differs significantly from the authentic product.
Step 5 – Perform Quantitative Analysis When Counterfeiting Is Suspected
If significant spectral differences are observed, laboratory personnel can perform quantitative analysis and compare the results with the manufacturer's specifications.
Typical procedures include:
Measuring absorbance at the characteristic wavelength.
Creating a calibration curve.
Calculating the concentration of the active ingredient.
Using a UV Vis machine provides a fast, non-destructive screening method for detecting potentially counterfeit products. It is particularly effective for quality control of both raw materials and finished products before they are released to the market.
