(C) Spectrum of pure methyl parathion (control experiment) The n

(C) Spectrum of pure methyl parathion (control experiment). The newly found peak might be due to the 4-nitrophenolate ions which are produced by the hydrolysis of methyl parathion in alkaline medium [20]. It is known that due to the catalytic hydrolysis of methyl parathion, two hydrolyzed products, 4-nitrophenolate ions and sodium di-O-methyl CH5183284 research buy thiophosphonate are produced (Figure 1). The literature confirms that 4-nitrophenolate ion shows a characteristic absorption peak at 400 nm [21]. The increase in the concentration of methyl parathion in the mixture quantitatively increases the amount of the 4-nitrophenolate ions in the medium which are reflected in the absorption spectra (Figure 3A). A calibration curve between

the absorption

coefficient of the 400-nm peak and the concentration of the pesticide allows quantitative estimation of the methyl parathion Selleckchem Ro 61-8048 present in a sample at ppm levels (Figure 3B). This calibration curve enables the estimation of methyl parathion indirectly by estimating the 4-nitrophenolate ions present in the medium. The corresponding decrease in the absorption peak of GNP at 532 nm may be due to the agglomeration of GNP which is facilitated by the presence of the other hydrolyzed product sodium di-O-methyl thiophosphonate containing sulfur. The formation of agglomeration of GNP is indicated by the broadening of the 532-nm peak in the presence of methyl parathion. A control experiment (Figure 3C) was carried out by PSI-7977 mw taking methyl parathion only, and no peak was Rolziracetam found at 400 nm. The peak at 400 nm emerges only when the hydrolysis of methyl parathion occurs in the presence

of GNP in water. Figure 4A shows the TEM images of GNP produced from a 5:5 composition of tomato extract. The particles are mostly spherical, and their sizes varied from 5 to 20 nm. A histogram plot (Figure 4B) shows the distribution of particles of different sizes. Selected area diffraction (SAED) pattern shown in Figure 4C illustrates the crystalline nature of GNP. Figure 4 TEM micrographs, particle size distribution histogram, and SAED pattern of GNP. (A) TEM micrographs of GNP with tomato extract. (B) Particle size distribution histogram of spherical GNP, and (C) corresponding SAED pattern of GNP. Figure 5A shows the representative TEM images of GNP with SDS in alkaline medium. The histogram of it is shown in Figure 5B. The significant changes are observed in the size of the particles. The particles become of uniform sizes, and the sizes reduced to 5 to 10 nm. SDS, being a strong capping agent stabilizes the gold nanoparticles as soon as nucleation happens and thereby restricts the nanoparticles to a finite size. As a result, nearly monodispersed gold nanoparticles of sizes 5 to 10 nm were obtained. Figure 5 TEM micrographs, particle size distribution histogram, SDS-capped GNP with methyl parathion, and SAED pattern of GNP. (A) TEM micrographs of SDS-capped GNP with tomato extract.

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