Ultraviolet Transmittance (UVT%) measures how much UV light at 254 nm passes through 1 cm of water. To measure it you will need a spectrophotometer (we recommend using a portable one), quartz cuvettes, and reference water (can be distilled water).

How to Measure UVT%:

  1. Prepare the Spectrophotometer
    • Turn on the spectrophotometer and allow it to warm up per the manufacturer’s instructions.
    • Set the wavelength to 254 nm (if using a mobile spectrophotometer, it is pre-set to 254 nm).
  2. Calibrate the Instrument
    • Use a clean cuvette filled with deionized or ultrapure water as a reference (blank).
    • Insert the blank into the spectrophotometer and set the instrument to 100% transmittance (or 0 absorbance).
  3. Collect the Sample
    • Obtain a representative water sample.
  4. Prepare the Sample
    • Rinse a clean cuvette thoroughly with the water sample.
    • Fill the cuvette, ensuring no air bubbles are trapped.
    • Wipe the outside of the cuvette with a lint-free cloth.
  5. Measure the Sample
    • Insert the sample cuvette into the spectrophotometer.
    • Record the transmittance value.
  6. Document the Results
    • Note the UVT percentage and relevant conditions (e.g., temperature, time, and sample source).
  7. Clean the Cuvette
    • Rinse with reference water, clean, and dry before storage.