Spectrophotometric detection of organophosphate diazinon by porphyrin solution and porphyrin-dyed cotton fabric

The absorbance spectrum of porphyrin meso-tetraphenylporphine (TPP) shifts to a shorter wavelength when interacting with the organophosphate diazinon. This spectral shift in the presence of diazinon is more obvious in the difference spectra (TPP + diazinon) − TPP, and can be observed in porphyrin–DMF solution and porphyrin-dyed cotton fabric. In solution, the difference spectrum has a peak at 412 nm and a trough at 421 nm. For TPP dyed cotton fabric, the difference spectrum has a peak at 415 nm and a trough at 430 nm. The absorbance difference (ΔA) between peak and trough in the difference spectra has a linear relationship with diazinon concentration. This spectral property of porphyrin can be used to detect diazinon in the environment. Diazinon can be detected at 0.5 ppm level by TPP in solution, and at 11 ppm level by TPP dyed cotton fabric. The solid state detection capability of TPP dyed cotton fabric implies that textiles can serve as the platform for chemical sensors.