Variation of Stokes Shift and Peak Wavelength Shift as a Sensing Probe for Detection of Lead in Water Using Laser...

Water contamination through the dissolved toxic heavy metal ions is becoming a serious issue seeking the worldwide attention of the researchers. The tap water used for drinking is primarily exposed to the household plumbing system and may dissolve toxic lead metal through pipes, soldered joints and that may cause a number of diseases in children, adults and pregnant women. Thus detecting lead is getting utmost importance among the researchers. Present work explains a method of detecting trace concentration of lead in water using laser induced fluorescence resonance energy transfer (LIFRET). The fluorescence resonance energy transfer (FRET) is observed between 1, 8- naphthalimide as donor and rhodamine-B as an acceptor by exciting it with a laser radiation of 405 nm. With the addition of the lead contained water in pure solution of the FRET pair the emission peak wavelength shifts from 630.27 nm of its value for pure solution. The amount of stoke shift decreases with increase in lead concentration with a gradual increase in intensity of the fluorescence spectra. Based on variation of stoke shift and peak wavelength shift of FRET spectra a novel and specific method is described for the detection of lead up to its maximum permissible limit of 0.00001 g l^-1 set by the world health organization(WHO). The method described is relatively cost effective, handy and may have reasonably effective in situ measurement for detecting lead in the contaminated areas.