Sodium Hydrosulfite-Hydrogen Peroxide Chemiluminescence And Application In The Determiantion Of Oxygenated Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs)are distributed in thewater, airborne particulates and soil samples. More and more attentionshave been paid on PAHs. It is very important to monitor and controlvariations of PAHs in environment. Chemiluminescence is one kind ofvery sensitive method. The instrument is simple and easy to be operated.In this research, we established a very sensitive chemiluminescencemethod to determine oxygenated polycyclic aromatic hydrocarbons inairborne particulates. In addition, we study the mechanism ofNaHSO₃-H₂O₂. The main works of this research are shown as follow:1. In this work, a chemiluminescence (CL) reaction between hydrogenperoxide (H₂O₂) and sodium hydrosulfite (NaHSO3) was developed.Hydroxyl radical (.OH), and sulfite radical (.SO₃^-) were the mainintermediates generated in NaHSO3-H2O2CL system. Inhibition effects of radical scavengers such as thiourea, chloride ion, nitro blue tetrazoliumchloride (NBT), and5,5-dimethyl-1-pyrroline N-oxide (DMPO)indicated the existence of these two radicals. Singlet oxygen (1O2) andexcited sulfur dioxide (SO₂*) were emitting species involved inNaHSO3-H2O2CL system.1O2were confirmed by1,4-diazobicyclo [2,2,2] octane (DABCO) and sodium azide (NaN3), which were specific1O2scavengers. In addtion, electron spin resonance (ESR) spectra clearlyshow the existence of1O.2andOH. Alcoholic solvent, especiallyn-butanol, enhanced the ultra-weak CL emission more than forty times.The enhancing effect of alcoholic solvent on NaHSO3-H2O2CL systemwas ascribed to the formation of solvent cage, which can accelerate thereaction rate and protect the emitting species from quenching by water.CL emission of NaHSO3-n-butanol-H₂O₂system was measured by cut-offfilters. The maximum wave length was located around490nm, whichbelongs to¹O₂. The wide peak from400nm to600nm is thecharacteristic peak of SO₂^-.2. In this research, a highly sensitive chemiluminescence methodbased on a sodium hydrosulfite (NaHSO3)-hydrogen peroxide (H2O2)reaction for the determination of OH-PAHs was developed. The proposedmethod was applied to determine the concentrations of1-OHP in airborneparticulates. The response of this system was linear in the range from0.5to50pmol (R²=0.9983). The limit of detection for1-OHP was100fmol (S/N=3).1-OHP in airborne particulates was well separated frominterfering compounds using an ODS column with75%methanol as themobile phase in isocratic mode. The proposed method was successfullyused to determine the1-OHP in airborne particulates collected inKanazawa, Japan. The average concentration of1-OHP in the atmospherewas2.0pg/m³.3. An ultra-weak chemiluminescence (CL) was observed whensodium hydrosulfite (NaHSO3) reacts with hydrogen peroxide (H₂O₂),and enhanced70times by adding10pmol benzo[a]pyrene-7,10-quinone(7,10-BaPQ). The CL reaction is fast and it reached maximum intensity in0.1s, and then decayed to base line in3s. Mechanism of NaHSO3-7,10-BaPQ-H₂O₂system were investigated by CL spectrum, radicalscavengers and electron spin resonance (ESR). Hydroxyl radical (.OH),super oxide anion radical (.O₂^-), and sulfite radical (.SO₃) were generatedin the NaHSO3-7,10-BaPQ-H₂O₂system. Reduction of7,10-BaPQby.O-2radical gave excited semiquinone, which showed strong CLemission when decayed to its ground state. Maximum CL emissionwavelength was located at440nm, which may belong to the excitedsemiquinone. This CL system was developed as post column detection ofhigh performance liquid chromatography for the determination of7,10-BaPQ. Linearity ranged from50fmol to20pmol (R2=0.9995) withlimit of detection of30fmol (S/N=3). The proposed method was used to determine7,10-BaPQ in airborne particulates. Average atmosphericconcentrations of7,10-BaPQ in Kanazawa in December2010andWajima in October2007were2.0and1.6pg/m3, respectively.