[Resonance scattering detection of trace Hg2+ using herring sperm DNA modified nanogold].

In pH 7.0 tris-HCl buffer solutions and in the presence of 0.017 mol x L(-1) NaCl, herring sperm DNA was combined with gold nanoparticles in size of 10 nm to form stable complex, and the NaCl did not cause the aggregation of the gold nanoparticles. Upon addition of Hg2+, that reacted with DNA to form more stable complex of Hg(2+)-DNA, and the gold nanoparticles aggregated to from larger nanogold clusters that led to considerable enhancement of the resonance scattering intensity at 572 nm enhanced considerably. The effect of GN concentration, DNA concentration, NaCl concentration, incubation time, and temperature, and ultrasonic irradiation was considered respectively, the conditions of 3.87 microg x mL(-1) GN, 11.7 microg x mL(-1) DNA, pH 7.0 Tris-HCl buffer solutions, 17 mmol x L(-1) NaCl, and incubation 10 min at 37 degrees C under the ultrasonic irradiation were chosen for use. Under the conditions, the enhanced resonance scattering intensity at 572 nm was linear to the Hg2+ concentration in the range of 3.3-3 333.3 nmol x L(-1), with regress equation of delta572 nm = 0.019c+5.0, coefficient of 0.999 1, and a detection limit of 2.5 nmol x L(-1) Hg2+. Results of interference tests showed that 30 micromol x L(-1) Mn2+, 33 micromol x L(-1) Mg2+ and Zn2+, 100 micromol x L(-1) Cd2+, 200 micromol x L(-1) Fe3+, and 420 micromol x L(-1) Mo6+, Pb2+ and Cu2+ did not interfered with the determination of 0.33 micromol x L(-1) Hg2+. That is, this resonance scattering spectral assay is of good selectivity. This assay was applied to the detection of Hg(II) in water sample, with a relative standard deviation of 5.1%, and the results were in agreement with that of the cool vapor atomic absorption spectrophotometry.

Determination of trace chlorine dioxide based on the plasmon resonance scattering of silver nanoparticles.

A plasmon resonance scattering (PRS) method for chlorine dioxide is reported based on the oxidization of silver nanoparticles (NPs) by it, in pH 9.1 ammonia-ammonium nitrate buffer solutions. Silver NPs exhibit strong PRS signals at 470nm, and can be oxidized by ClO(2), which results in PRS quenching at 470nm. It was found that the PRS quenching intensity is proportional to the concentration of chlorine dioxide over the range of 0.0011-0.185microg/mL, with a detection limit (3sigma) of 0.00050microg/mL and the correlation coefficient of 0.9995. The method is simple, rapid and cost effective. It was applied to the determination of chlorine dioxide in drinking water, with satisfactory results.

[A fluorescence quenching method for the determination of trace chlorite in water with rhodamine B].

In acidic sodium acetate-HCl buffer solution containing KI, Rhodamine B (RhB) has a fluorescence peak at 580 nm. When ClO2(-) exists fluorescence quenching occur. The fluorescence quenching intensity is linear with the concentration of ClO2(-) in the range of 0.0218-0.51 microg x mL(-1). Based on this, a new, simple, sentisive fluorescence method has been proposed for the determination of ClO2(-) in water, with satisfactory results.

[A new fluorescence quenching method for the determination of trace ClO2 in water using silver nanoparticles].

In pH 9.1 NH4Cl-NH3 x H2O buffer solution, there is a fluorescence peak at 470 nm for silver nanoparticles. A fluorescence quenching takes place when it was oxidized by ClO2. The intensity of fluorescence quenching is linear with the concentration of ClO2 in the range of 0.0011-0.185 microg x mL(-1). The detection limit is 0.004 7 microg x mL(-1). A new fluorescence method has been proposed for the determination of ClO2 in water samples with satisfactory results.

A novel, simple and sensitive resonance scattering spectral method for the determination of chlorite in water by means of rhodamine B.

A new resonance scattering method was proposed for the determination of chlorite, basing on the resonance scattering effect of rhodamine dye. In HCl-sodium acetate buffer solution, chlorite oxidizes I- into I2 and the reaction of I2 and excess I- results in I3- It is respectively combined with rhodamine dyes, including rhodamine B (RhB), butyl rhodamine B (b-RhB), rhodamine G (RhG) and rhodamine S (RhS), to form association complex particles, which exhibit stronger resonance scattering (RS) effect at 400 nm. The chlorite concentration of ClO2- in the range of 0.00726-0.218 microg/ml, 0.0102-0.292 microg/ml, 0.00726 0.145 microg/ml and 0.0290 0.174 microg/ml is respectively linear to the RS intensity of association complex particle systems at 400 nm for the RhB, b-RhB, RhG and RhS. The detection limits of the four systems were respectively 0.00436, 0.00652, 0.00580 and 0.01450 microg/ml ClO2-. In the four systems, the RhB system possesses good stability and high sensitivity. It has been applied to the analysis of chlorite in wastewater with satisfactory results.

A novel and selective spectral method for the determination of trace chlorine in water basing on the resonance scattering effect of rhodamine B-I(3) association nanoparticles.

In Na(2)HPO(4)-citric acid buffer solution, Cl(2) can oxidize I(-) to form I(2) and then it reacts with excess I(-) to form I(3)(-). The I(3)(-) combines respectively with rhodamine dyes, including rhodamine B (RhB), butyl rhodamine B (b-RhB), rhodamine 6G (RhG) and rhodamine S (RhS), to form association particles which give stronger resonance scattering (RS) effect at 400 nm. The RS intensity of the RhB, b-RhB, RhG and RhS systems is proportional to chlorine concentrations in the range of 0.008-1.74, 0.019-1.33, 0.021-2.11 and 0.019-2.04 microg/mL Cl(2), respectively. The detection limits of the systems were 0.0020, 0.0048, 0.0063 and 0.0017 microg/mL, respectively. In them, the RhB system has good stability and high sensitivity, and has been applied to the analysis of chlorine in drinking water, with satisfactory results which is in agreement with that of the methyl orange (MO) spectrophotometry.

[Effect of cation surfactants on absorption spectra of silver nanoparticle in liquid phase].

Yellow Ag nanoparticles, with diameter of 20 nm, exhibit a resonance absorption peak at 400 nm. After adding some cation surfactants (CS), the absorbance at 400 nm becomes weak, (namely, there exists hypochromic effect), but the absorbance at wavelengths longer than 400 nm is enhanced and shows a red shift. When adding concentration of CS, the absorbance at wavelengths longer than 400 nm becomes weak again, the peak at 400 nm is enhanced (namely, there exists hyperchromic effect) and the absorption peaks show a blue shift. The results showed that this is caused by the strong hydrophobic force and electrostatic force between the CS and silver nanoparticls, which results in a change in the silver nanoparticle shape.

A new and sensitive resonance-scattering method for determination of trace nitrite in water with rhodamine 6G.

In the medium HCl-KI-rhodamine dye, NO(2) (-) reacts with excess I(-) to form I(3) (-) and the I(3) (-) and rhodamine dye combine to form an association particle which gives three resonance-scattering (RS) peaks at 320 nm, 400 nm, and 595 nm. In systems containing rhodamine 6G (Rh6G), rhodamine B (RhB), rhodamine S (RhS), and butyl rhodamine B (BRhB) the resonance scattering intensity at 400 nm is proportional to nitrite concentrations in the range 2.3-276 ng mL(-1), 9.2-184 ng mL(-1), 9.2-184 ng mL(-1), and 9.2-92 ng mL(-1), respectively. Because of the high sensitivity, wide linear range, and good stability of the Rh6G system, it has been used for determination of nitrite in water samples, with satisfactory results. The spectral results have been used to verify that the formation of (Rh6G.I(3))(n) association particles and their interface with the system are main factors that cause the RS enhancement.

[Spectral properties of the association particle system of quinine-[PtI6]2- and its analytical application].

In 0.01 mol x L(-1) HCl medium, red color [PtI6]2- and quinine combine to form association molecule. The molecules aggregate automatically owing to strong hydrophobic and molecular forces. And PtI6-quinine association particles with violet-red color formed. It exhibits three resonance scattering peaks at 310 nm, 400 nm and 610 nm, and a Rayleigh scattering peak at 470 nm. The absorption values all increase in the wavelength range of 350-740 nm, and the fluorescence peak at 450 nm was quenched. Under the conditions chosen, the quinine concentration in the range of 0-40 x 10(-6) mol x L(-1) is linear to the A(620 nm) value. The mole absorption coefficient epsilon(620 nm) is 1.31 x 10(4) L x mol(-1) x cm(-1). The results show that the association particles produce the resonance scattering effect, fluorescence quenching and the violet-red color.