The acid catalyzed nitration of methanol: formation of methyl nitrate via aerosol chemistry     

Laura T. Iraci  Brent G. Riffel  Carly B. Robinson  Rebecca R. Michelsen  Rachel M. Stephenson 《Journal of Atmospheric Chemistry》2007,58(3):253-266

The aqueous phase acid-catalyzed reaction of methanol (CH₃OH) with nitric acid (HNO₃) to yield methyl nitrate (CH₃ONO₂) under atmospheric conditions has been investigated using gas-phase infrared spectroscopy. Reactions were conducted in aqueous sulfuric acid solutions (50.5–63.6 wt.%) with [CH₃OH] = 0.00005–0.005 M and [HNO₃] = 0.02–0.21 M, at 278.2–328.6 K. Methyl nitrate production rates increased linearly with CH₃OH and HNO₃ concentrations and exponentially with sulfuric acid weight percent within the regime studied. Rates increased linearly with nitronium ion concentration, indicating that the reaction involves as the nitrating agent under these conditions. At 298 K, the rate of methyl nitrate production can be calculated from k _obs [CH₃OH][HNO₃], where k _obs  = 2.337 × 10⁻¹³(exp(0.3198*wt.% H₂SO₄)) when the solubility of CH₃ONO₂ in acidic solution is approximated by H* for pure water. The temperature dependence of the rate coefficient is related to solution composition, with activation energies of 59 and 49 kJ/mol at 51.1 and 63.6 wt.% H₂SO₄, respectively, when k is calculated from rate. The temperature dependence has also been parameterized for application to the atmosphere, but the small quantities of present in aerosol particles will result in methyl nitrate production rates too small to be of significance under most atmospheric conditions. An erratum to this article can be found at  相似文献   

石墨炉原子吸收光谱法测定血液中微量铅     

任以发  孙齐  胡俊 《江苏地质》2007,31(2):139-142

研究了石墨炉测定血液中微量铅的适宜条件,用氘灯校正背景,磷酸二氢铵作基体改进剂,方法具有准确、快速、简便等优点,用于扬州妇幼保健院实际样品的测定,结果预示我们的环境不容忽视,血液中铅含量能够比较真实地反映生物个体受到的污染程度。  相似文献   

A simplified resorcinol method for direct spectrophotometric determination of nitrate in seawater     

Jia-Zhong Zhang  Charles J. Fischer 《Marine Chemistry》2006,99(1-4):220

A direct, spectrophotometric method has been adapted for quantitative determination of nitrate concentrations in seawater. The method is based on nitration of resorcinol in acidified seawater, resulting in a color product. The absorption spectrum obtained for the reaction product shows a maximum absorption at 505 nm, with a molar absorptivity of 1.7 × 10⁴ L mol^− 1 cm^− 1. This method has a detection limit of 0.5 μM and is linear up to 400 μM for nitrate. The advantage of this method is that all reagents are in aqueous solutions without involving cadmium granules as a heterogeneous reactant, as in conventional methods, and therefore is simple to implement. Application of the resorcinol to seawater analysis demonstrated that the results obtained are in good agreement with the conventional approach involving the reduction of nitrate by cadmium followed by diazotization.  相似文献