Abstract:
Chronic Kidney Disease of unknown etiology (CKDu) is a crisis in the dry zone of Sri
Lanka. Farmers in this region use chemical herbicides in paddy fields and glyphosate is
one of the herbicides widely used. The amount of glyphosate used in the fields varies
according to the wish of each farmer and the lack of awareness of farmers of the risk of this
compound leads to excessive accumulation of chemicals in the soil. The excess fertilizers
and herbicides ultimately end up in groundwater aquifers from which water is extracted for
drinking. The complex of glyphosate can be considered as one of the suspects in the CKDu
in the dry zone. Water analysis is mostly carried out in laboratories which cause delays in
the results due to time taken for sample collection and transport. In situ measuring devices
could reduce the delays due to sampling transportation and analysis.
According to potable water standard SLS 614:2013 stipulated by the Sri Lanka Standards
Institution, the permissible phosphate level in drinking water is 0.05 mg L-1. Analytical
methods used to identify the orthophosphate in this range involve separation and detection.
Of the different methods available for detecting phosphate concentrations in water, such as
micro-column with ammonium molybdate, liquid waveguide capillary cell with
vanadomolybdate and ion chromatography, ion chromatography is widely used to detect
glyphosate. However, the vanadomolybdate method is more reliable for the onsite tests
than the other recommended methods.
In this study, attention was focused on designing a sensing device for automated detection
of glyphosate in water. Extracted water samples were mixed with the reagent of
vanadomolybdate and the color development was measured using a light source with photo
detector. A reference signal was used to compare the signal emitted by the sample. Signals
from the photo detectors were transmitted to the microcontroller to indicate the glyphosate
concentration level to the user. The development of this device would be useful to identify
the risk of consumption of water extracted from any suspected source
