VLux TPro

5-in-1 MiniSonde for detection and monitoring of tryptophan in water


Chelsea’s state of the art miniature, high quality TPro.


Tryptophan measurement has been applied to the detection of tryptophan in water and is becoming increasingly recognised as a valuable water quality parameter in its own right.


Tryptophan is an essential amino acid in the human diet and is the main component of protein fluorescence. It is associated with microbial activity and tryptophan measurement has been applied to sewage and faecal contamination of waste waters, including: agricultural runoff, effluent from waste water treatment, and contamination of processed waters.


Features & Applications


Chelsea’s miniature, high quality TPro provides detection and monitoring of tryptophan in water.


  • 5 key parameters including
    • Tryptophan
    • CDOM
    • Chlorophyll a & c
    • Turbidity (ISO 7027:1999 compliant)
    • Absorbance
  • Fluorescence automatically correction for absorbance and turbidity
  • Highly sensitive for detection of tryptophan at the sub-ppb level
  • Integral biofouling protection using both UV light and copper bezels around windows
  • Compact and robust design, measuring194 mm (H) x 50 ± 0.05 mm (D)
  • Ideal for standalone fieldwork or system integration including: CTDs, AUVs, ROVs and gliders
  • Integrated logging as standard, battery packs available on request
  • Compatible with Hawk and Watchkeeper for data display in the field
  • 6000 m depth rating


  • Assessment of the overall health of a water body
  • Quantitative data to aid assessment of environmental status
  • Water quality assessment and monitoring in catchments
  • Sewage contamination
  • Groundwater contamination
  • Ecological health
  • Early ‘bloom’ detection prior to cell growth



VLux In-depth


Why measure CDOM and Chlorophyll as well as Tryptophan?

  • Measuring CDOM and chlorophyll as well as Tryptophan allows the background fluorescence intereference to be separated from the Tryptophan signal, improving the accuracy of the Tryptophan reading.

CDOM – A valuable addition to VLux

  • VLux measures CDOM for corrections but it is also a valuable parameter in its own right. It gives a holistic overview of organic content and tryptophan.
  • In addition, when aromatics combine with halides (e.g. trihalomethanes), they become carcinogenic. This is highly relevant for the water industry – if CDOM is not effectively removed before chlorination, potentially harmful compounds could be added to the water supply.

Why correct for absorbance and turbidity?

  • As the concentration of Tryptophan increases, the compounds themselves absorb light, resulting in a non-linear response of fluorescent signal against concentration.
  • Increased turbidity also has an impact, as light is scattered by particle and other matter in the water. Errors due to turbidity can be significant – adding the correction minimizes errors at even high turbidities.
  • In more challenging and dynamic environments such as rivers and estuaries, the impact of environmental factors cannot be ignored. VLux TPro measures turbidity and absorbance, applies the correction within the sensor and outputs environmentally corrected data.