Determination Of Formaldehyde And Acetaldehyde Associated To Atmospheric Aerosols By HPLC

Abstract

A rapid new analytical protocol was developed for the determination of formaldehyde and acetaldehyde associated to atmospheric particulate matter, at ng/m³ levels. The aerosols were collected on glass fiber filters (8″×10″) at face velocities ranging from 15 m/min to 23 m/min. Aliquots of 15.4 cm² were sonicated, for 20 min, with 5.0 mL of 0,01% 2,4-dinitrophenylhydrazine (DNPH), 1 % phosphoric acid. The liquid phase was then filtered and the separation and quantification of the corresponding 2,4-dinitrophenylhidrazone (DNPHo) derivatives carried out by reverse phase HPLC. Acetonitrile:water (57:43, v/v) as mobile phase at 1.0 mL/min and absorbance detection at 350 nm and 365 nm for, respectively, formaldehyde-DNPHo (0.04 AUFS) and acetaldehyde-DNPHo (0.01 AUFS) were used. The precision for four different aliquots, from a 8″×10″ glass fiber filter, were under 0.04% for formaldehyde and 14.16 % for acetaldehyde. In Salvador, Bahia, Brazil, formaldehyde and acetaldehyde were determined, respectively, in the range of 6.8 ng/m³ to 27.3 ng/m³ and 9.1 ng/m³ to 54.6 ng/m³.     

两性化合物与离子对试剂的混合物作流动相的流动相离子色谱法测定气溶胶中水溶性阴离子

用流动相离子色谱法(MPIC),以两性化合物与离子对试剂的混合溶液为流动相,在C18柱上抑制电导检测分析气溶胶中常规无机阴离子和有机酸。实验采用氢氧化四丁基铵(TBAOH)为离子对试剂,与两性化合物3-(N-吗啉)-1-丙磺酸(MOPS)混合,加入Na2CO3无机添加剂作流动相,其浓度为1mmol／L TBAOH／5mmol／LMOPS／0．5mmol／LNa2CO3。分离柱采用硅质C18柱,抑制电导检测。可以较好地分离和检测常见的无机和有机阴离子。该方法具有较好的重现性和线性关系,F^-、Cl^-、NO2^-、Br^-、C3H3O3^-、NO3^-的回收率分别为102．0％、104．6％、102．4％、97．8％、97．75％和102．5％;检出限分别为0．017、0．014、0．0048、0．036、0．16和0．017mg／L。     

Application of the Combustion Method in a Closed Flask to the Lead Determination in Atmospheric Aerosols

Abstract

The destruction of the filter for metal determination in atmospheric aerosols is an important step in the analysis. Nowadays the decomposition of this kind of sample has not been completely solved, so it is interesting to study new methods for filter sample attack. In the present work the application of the combustion method in a closed flask for mixed cellulose esters filter decomposition for lead determination is proposed. For this purpose optimum operating conditions as stopper flask design, sample size, flask volume, shaking time and volume and concentration of absorbing solution are established, and accuracy and precision of the proposed method using AAS for the measurements is given. The results obtained by the closed flask combustion are compared with those found by wet attack with HNO₃. The method proposed is rapid, has low reagent contamination and no loss of lead by volatilization or by amalgamation occurs. This method shows an accuracy and a precision in good agreement with the standard method.     

Determination of Atmospheric Ozone Using the Centrifugal Photometric Analyzer

Abstract

The production of formaldehyde from the selective cleavage of the double bond of 4-allyl-2-methoxyphenol (eugenol) by ozone permits the specific determination of ozone in air samples. The formaldehyde is determined by a modification of the West-Gaeke procedure for sulfur dioxide. Increased speed, accuracy, and reproducibility is achieved because of the parallel analysis technique of the centrifugal photometric analyzer.     

Determination of Fluorescence Efficiencies of Fluorophores in Highly Absorbing Solutions Using Right Angle Geometry

Abstract

The determination of fluorescence quantum yields by measurements of fluorescence intensities of unknown and standard fluorophores at maximum possible fluorescence intensity (high absorbance) is simple and offers some distinct advantages over measurements with weakly absorbing solutions of the fluorophores.     

Determination of Atmospheric Polycyclic Aromatic Hydrocarbons Using Accelerated Solvent Extraction

Abstract

An accelerated solvent extraction (ASE) method has been developed for the determination of polycyclic aromatic hydrocarbons (PAHs) present in both atmospheric particulate and gaseous phases in this study. Extraction parameters such as the combination of solvents, extraction temperature, and static extraction time were investigated and optimized. Effective extraction was achieved using a 3:1 mixture of n-hexane and acetone as extraction solvents at 100°C in 30 min for all the compounds studied. The optimized extraction method was compared with conventional extraction methods and validated using National Institute of Standards and Technology (NIST)–certified standard reference material (SRM) 1649a. The recoveries obtained for certified 12 PAHs were in the range of 82–126% with relative standard deviation (RSD) between 6 and 28%. The validated ASE technique was used followed by gas chromatography–mass spectrometry (GC-MS) for the determination of PAHs distributed between gaseous and particulate phases in the atmosphere of Singapore. Total average concentrations of PAHs in air samples were 33.54 ± 19.32 ng m^?3, with 4.72 ± 2.80 ng m^?3 in particulate phase and 28.82 ± 16.92 ng m^?3 in gaseous phase, respectively. The results obtained from this study are compared to those reported from other areas of the world.     

固体基质室温燐光法测定L-色氨酸

本文提出在Na_2 CO_3存在下,以NaI为重原子微扰剂,以滤纸为基质的L-色氨酸的室温燐光(RTP)测定法。本法不需通干燥气体,工作曲线的线性范围较宽,用于谷物试样分析,得到了满意的结果。     

Analysis of Atmospheric Aerosols by Atomic Emission Spectrometry with Electrical Discharge Sampling

A procedure has been developed for the determination of the concentration of heavy metals (Pb, Mn, Cu, Ni, Zn, and Cd) in atmospheric air by atomic emission spectrometry with gas-discharge sampling onto the end of a standard carbon electrode. A design of a two-section sampler is proposed; the sampler provides the rapid determination of deposition factors for heavy metals contained in aerosol particles deposited onto the end of a carbon electrode. Examples of determining metal concentrations in a model sample of air and in atmospheric air and determination limits of metals deposited onto the end of a carbon electrode are given.     

滤膜法测定工业废水中悬浮物

不可滤残渣(悬浮物)是指不能通过孔径为0．45μm滤膜的固体物。依据《水和废水监测分析方法》(第四版),测定悬浮物标准分析方法为滤膜法。方法中对滤膜的直径和孔径均作出明确的规定,分别为45～60mm和0．45μm,一般以5～100mg悬浮物量作为量取试样体积的实用范围Ⅲ。     

X-射线荧光光谱滤纸片法测定食油中的磷

本文介绍了用X射线荧光光谱滤纸片法测定食油中磷的方法。这种方法制样简单,植物油不经过任何化学处理就可直接测定,分析速度快,测量数据可靠,结果令人满意。     

Comparison of the Results of Atomic Absorption and X-ray Fluorescence Analysis of Metals in Atmospheric Aerosols

Factors responsible for the systematic discrepancies between the results of atomic absorption (standard procedure) and X-ray fluorescence determination of metals in atmospheric aerosols preconcentrated on a filter were studied. Patterns describing the errors in the results of determining Fe, Cu, Pb, Zn, Mn, and Cr by the proposed procedures depending on the type of the metal compound and the concentration of SiO₂ in aerosol particles were found. It was shown that the underestimation of the results of atomic absorption analysis in comparison to those obtained by X-ray fluorescence is due to the incomplete decomposition of some analyte compounds and the adsorption of Fe, Cu, and Pb on the precipitated SiO₂.     

Fluorometric Determination of Atmospheric Nox

Nitrogen oxides in urban air are mostly from exhaust gases emitted by internal-combustion engines with a considerable impact on human health. It plays an important role in the generation of photochemical smog and photochemical oxidants such as ozone and peroxyacetyl nitrate (PAN). And it is a precursor of nitrous acid, nitric acid and fractions of solid nitrates which are important in the acid rain chemistry.     

Technologies of Atmospheric Electrodynamics Based on Ionized Dispersed Media

Russian Journal of General Chemistry - Parameters of ionized dispersed microparticles formed by hydride compounds, one of which is water, are considered. Properties of hydrogen compounds and...     

硝酸铵对SO2在大气颗粒物表面气-粒转化影响的模拟研究

利用流动态的原位傅里叶变换红外漫反射光谱(DRIFTS)对含硝酸铵气溶胶(以α-Fe₂O₃为主模拟气溶胶)与SO₂的非均相反应进行了研究, 比较了硝酸铵与其它金属氧化物(CaO, MgO, α-Al₂O₃和SiO₂)与SO₂反应的情况.实验结果表明, 硝酸铵和α-Fe₂O₃混合颗粒物比硝酸铵和其它金属氧化物混合颗粒与SO₂反应的吸附系数高, 表明α-Fe₂O₃比其它金属氧化物催化能力变强.利用BET面积作为反应活性表面积, 发现含有6％(质量分数)NH₄NO₃的α-Fe₂O₃混合颗粒物与SO₂反应具有最高的比表面积吸附系数(γ_BET=2.42×10^-9), 比纯氧化铁的反应高了近1.8倍.而纯NH₄NO₃颗粒与SO₂不发生反应, 表明少量硝酸铵的存在在一定程度上提高了SO₂在气溶胶颗粒物表面转化成硫酸盐的能力. 本文还讨论了含硝酸铵气溶胶与SO₂的反应机制及其对大气环境的影响.     

石墨探针采样／石墨炉原子吸收光谱测定大气微粒物质中的痕量铁

采用一定规格的石墨探针直接收集大气微粒物质，并采用原子吸收光谱法测定其中的痕量铁。     

Spectrofluorimetric Determination of Piroxicam in Pharmaceutical Preparations and Spiked Human Serum Using Micellar Media

The fluorescence properties of piroxicam in various micellar media were investigated. It was found that the presence of 0.05M sodium dodecyl sulfate (SDS) surfactant (pH 1.5–2, nitric acid) causes an approximately 5-fold enhancement in the fluorescence of this drug. An experimental design approach based on central composite design was used to investigate the influence of the main variables (pH, SDS concentration and temperature) on the fluorescence signal. Based on the obtained results, a micelle-enhanced fluorescence method was developed for the determination of piroxicam in pharmaceuticals and also in spiked human serum (after extraction with diethyl ether). The linear calibration ranges of the methods were 0.05–1.5 and 0.2–10µgmL^–1 for aqueous solution and serum samples, respectively. The detection limits were 0.015 and 0.10µgmL^–1 in aqueous and serum samples, respectively.Received November 24, 2002; accepted April 13, 2003 Published online August 8, 2003     

Determination of Oxygen in Gas Media Using a Gas-Diffusion Electrode Based on Manganese Dioxide

It was shown that manganese dioxide isolated from a fluoride-containing electrolyte can be used as an electrode material for determining oxygen in gas media.     

Spectrofluorimetric Determination of 2-Naphthol in A Pharmaceutical Shampoo Using Anionic SDS Micellar Media

Abstract

Fluorescent characteristics of 2-naphthol were studied in aqueous solution and in micellar solutions of sodium dodecyl sulfate (SDS), hexadecyl-trimethylammonium bromide (HDTB), and Triton X-100. The enhancement of 2-naphthol fluorescence in SDS neutral solutions was used to establish a method for the determination of 2-naphthol. The method was applied in a medicinal shampoo.     

大气丙酮碳同位素组成测定方法的研究

利用气相色谱/燃烧/同位素比值质谱(GC/C/IRMS)分析技术,研究了具有不同碳同位素组成的丙酮与衍生剂2,4-二硝基苯肼(DNPH)的液相反应及其相应的气相反应实验过程中的碳同位素效应,探讨了以该方法测定大气丙酮碳同位素组成的可行性。研究结果表明,在衍生化过程中不会产生碳同位素分馏。本实验通过测定衍生剂DNPH与相应的衍生物的碳同位素值,大气中丙酮碳同位素组成通过质量平衡方程计算而求得。采用该方法对大气丙酮碳同位素组成的初步测定结果表明,具有相同排放源的大气丙酮碳同位素比值基本不变。本方法实验重现性好,测定精度高,可以用于分析大气丙酮的排放源研究。