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 1- into 12 and the reaction of 12 and excess 1- results in If. It is respectively combined with rhodaminc 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 μg/ml, 0.0102-0.292 μg/ml, 0.00726-0.145 μg/ml and 0.0290- 0.174 μg/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 0.01450μg/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.

Investigation on sampling artifacts of particle associated PAHs using ozone denuder systems

Polycyclic aromatic hydrocarbons （PAHs） are complex organic compounds which are identified as significant carcinogenic to human health. PAHs （mainly in particle phase） are susceptible to atmospheric oxidant gases, especially ozone, nitrogen oxides （NOx）, hydroxyl radical （OH）, and could be degraded on filters during sampling process, leading to an underestimation of ambient PAH concentrations. The goal of this work was to investigate particle associated PAHs sampling artifacts caused by ozone in summer of Beijing. Comparative sampling systems were operated simultaneously during the whole campaign, one with activated carbon ozone denuder, the other being set as conventional sampling system. Activated carbon denuder was testified to be highly efficient to eliminate ozone from air stream. In general, nine particle-bound PAHs observed from conventional sampler were all lower than those from ozone denuder system. The total PAHs （particle phase） concentration was averagely underestimated by 35.9% in conventional sampling procedure. Benzo[a]pyrene （BaP） had the highest percentage of mass loss. founded to have influences Ambient temperature was on PAHs sampling artifacts. High temperature can increase loss of particle associated PAHs during sampling.

A New and Sensitive Catalytic Resonance Scattering Spectral Assay for the Detection of Laccase Activity Using H2O2-1-TDMAC System

In pH 3.8 acetic acid-sodium acetate （HAC-NaAC） buffer solution, laccase exhibited a strong catalytic effect on the H2O2 oxidation of I- to form I2, and I2 combined with excess I- to form I3- that reacted with cationic surfactants of tetradecyl dimethylbenzyl ammonium chloride （TDMAC） to produce the （TDMAC-I3）n association complex particles, which exhibited a strong resonance scattering （RS） peak at 468 nm. Under the chosen conditions, as the concentration of laccase activity increased, the RS intensity at 468 nm （1468 nm） increased linearly. The increased RS intensity A1468 nm was linear to laccase activity in the range of 0.08-0.96 U/mL, with a regression equation of △1468 nm =88.8 U-1.9, and a detection limit of 0.02 U/mL laccase. This proposed method was applied to detect laccase activity in waste water, with satisfactory results.