Functionalized Silver Nano Particle Coated e-FBG Sensor For Specific and Rapid Detection of Chromium In Drinking Water

Hexavalent Chromium (
Cr (VI)
), a widely used material in industry has raised alarm due to its genotoxicity and carcinogenic nature. This study focuses on developing an effective optical sensor for determining
Cr (VI)
in drinking water, based on polyvinyl pyrrolidone (PVP) functionalized silver nanoparticles (AgNp) coated, clad etched Fibre Bragg Grating (e-FBG). The lone pair electrons present in Nitrogen (N) and Oxygen (O) present in PVP contribute towards the specific binding of
Cr (VI)
on the sensor surface, causing a shift in the Bragg wavelength (ΔλB) with
Cr (VI)
concentration. A liner relationship is observed in the current study indicates with molar concentration of
Cr (VI)
, with a detection limit (LOD) of 0.1 pM (0.0000052 ppb) and a working range of 0.1 pm to 100 μM (5.2 ppm), which is within the World Health Organization (WHO) permissible limit of 960 nM (50 ppb) in drinking water. The sensor is observed to be specific in nature when exposed to other interfering ions like arsenic (
AS(II)
), mercury (
Hg (II)
), lead (
Pb (II)
), magnesium (
Mg (II)
), sodium (
Na(I)
) and tri- valent chromium (
Cr (III)
). The sensor’s accuracy has been reconfirmed with Inductively Coupled Plasma Mass Spectroscopy (ICPMS), which showed an accuracy of (> 96%). A good recovery percentage (> 95%) for spiked drinking water samples highlights the sensor’s efficacy in case of real water sample analysis. A portable sensor with real time monitoring ability, combined with good reproducibility (S < 10 pM) and liner response make the present sensor, a potential onsite candidate for
Cr (VI)
determination in drinking water.