Chemical characteristics of aerosol insecticide deposition in indoor surfaces

We investigated the deposition rate of aerosol insecticide on through woollen surfaces inside a test chamber. Compared to floor surface, the deposition rate of aerosol insecticide active ingredient on table of 1 m high was up to 2.07 times for piperonyl butoxide, 1.64 times for tetramethrin and 2.95 times for permethrin represented by 0.51, 0.37 and 0.23 μg cm^?2 for the three molecules, respectively. Application of the household used cleaning to the woollen table surface decrease these concentrations by 61.32%, 45.01% and 59.80% for the three pesticides respectively, this cleaning procedure still not efficient for the floor surfaces. Moreover, indoor conditions permit the removal of 46.42%, 21.92% and 14.35% of the table surface deposition rate after one week, for the three pesticides, respectively. These conditions ensure the removal of only 28.72%, 20.69% and 24.05% of the three deposit molecules respectively on floor surface.     

Headspace analysis of chlorinated organic solvents in aerosol cans by gas chromatography

Summary A gas chromatographic (GC) method for the analysis of chlorinated solvents in chemical products in aerosol cans is described. Conditions for the sampling of chemical products from aerosol cans were optimized, so that the recovery of the solvents was better than 90%. Chlorinated solvents were identified by headspace GC—electron capture detection (ECD) as well as by GC — mass spectrometry. Headspace analysis employing the standard additions method and GC-ECD was used for the quantitation of chlorinated solvents. Analysis of 159 acrosol products, for various uses, revealed that 9% of these did not comply with the Danish Aerosol Regulations. The results of the study further indicated that aerosol products for haircare, paints and paint removers, and many others, can be formulated without chlorinated solvents.     

Gas chromatographic analysis and aerosol mass spectrometer measurement of diesel exhaust particles composition

Aerosol particles have important effects on human health, climate, regional visibility, and the deposition of acidic and toxic substances. The aerosols also have significant pharmaceutical and industrial applications. Trials of gas chromatographic analysis of extracts composition of diesel exhaust particles and aerosol mass spectrometer measurement of diesel exhaust particles composition are introduced in this paper. Usually, organic fraction of automotive exhaust particles are concentrated to 1 mL by Kuderna-Danish concentrator after extracted into dichloromethane by soxhlet extraction. Then, these extracts are analyzed by GC/MS. In the extracts from the diesel exhaust particles, there are over several thousands of components, for example paraffinic hydrocarbons, aromatics, oxygenates and other hydrocarbons.     

Gas chromatography of some prostaglandins

Summary The synthetic prostaglandin F_2α (PG_2α), used as an ovulation regulator, and abortion inducer, is contaminated with its Δ5-trans isomer. The ratio of the isomers was measured by capillary GC. The prostaglandin I₂ (PGI₂), a blood platelet aggregation inhibitor, easily decomposes to 6-ketoprostaglandin F_1α (6-keto PG_1α). Their ratio was measured by packed column GC. An unexpected, instantaneous methanol cleavage was observed during the GC analysis of the methyl ketal derivative of 6-keto PG_1α, forming a mixture of PGI₂ and Δ6-prostaglandin I₁ (Δ6-PGI₁). Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

A routine gas chromatographic method for the analysis of chlorofluorocarbons in aerosol cans

Summary A gas chromatographic (GC) method for the routine analysis of fully halogenated chlorofluorocarbons (CFCs) in aerosol cans is described. The identification of CFCs by GC was found to be in full agreement with those by GC-mass-spectrometery. The method has been applied to the analysis of CFCs in 448 aerosol products. The most commonly used fully halogenated CFC propellants in aerosol cans were found to be CFC11, CFC12 and CFC114.     

Sample preparation for gas chromatographic analysis of organic solvents in aerosol cans

Summary A method for the sampling of chemical products from aerosol cans is described. An aerosol can is frozen in liquid nitrogen, followed by puncturing the can and allowing the propellant to distill off. The conditions for the smaple preparation have been optimized. Solvent content in the products were analysed by headspace gas chromatography-mass spectrometry.     

Gas chromatography analysis of organophosphorous pesticides in plant samples

Summary The work presents a GC method for the determination of six organophosphorous pesticide residues in cabbage. Chopped cabbage was blended with acetone, then extracted with the mixture of n-hexane:methylene chloride (1:1). The extract was purified on a GPC column packed with BioBeads SX-3 gel. The pesticides were eluted with the mixture of methylene chloride:cyclohexane (1:1) at the flow rate of 0.5 mL min⁻¹. After concentrating the extract was analysed by GC. Nearly 100 samples of cabbage were analysed; trace residues of dimethoate (about 0.05 ppm) were found in 10 samples. The average recoveries of the pesticides were above 80% with a relative standard deviation mostly less than 10%. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997.     

Gas chromatography on 10 um silica particles

Summary Porous silica microparticles designed for modern liquid chromatography have proven effective in gas chromatography. Columns of 35–50 cm gave plate heights as low as 3.3 particle diameters and speeds of 2400 theoretical plates per second or 500 effective theoretical plates per second. Inlet pressures up to 70 atmospheres were required using hydrogen as carrier gas. The particles as received were too retentive for fast chromatography and gave asymmetric peaks. A coating of fluorosilicone oil overcame both problems. Other coatings were less effective. Bonded phases proved less satisfactory on both counts and also gave substantially less efficient columns and greater flow resistance. Column efficiency and flow resistance were sharply dependent on physical properties of the particles. The most efficient packing was clearly spherical particles of 5–10 μm diameter with narrow size distribution, pore diamters about 50 nm, BET surface areas of 25–50 m²/g and surfaces modified with trifluoropropyl silicone. A six-component hydrocarbon sample was separated in 33 s with a resolution of 4 for the most difficult pair and in 2.6 s with a minimal resolution. Performance was limited by end effects and by available pressure so that much better performance can be expected from longer columns and higher pressures.     

留兰香油的气相色谱质量评价

利用留兰香的毛细柱色相色谱的分析结果，提出了以α－蒎烯、β－蒎烯、苎烯、３－辛醇、薄菏醇、薄菏酮和香芹酮７ｆ个物质的量为质量评定指数。根据评定指数的总和值来评价留兰香精油的质量水平，结果与常规评香法基本一致。     

胶束电动色谱法分离与测定己烯雌酚片剂中的有效成分

建立了一种用来分离测定己烯雌酚的胶束电动色谱法,。通过对十二烷基硫酸钠、胆酸钠、脱氧胆酸钠3种表面活性剂进行比较,选定以60mmol/LSDS 10mmol/L硼砂的水溶液作为背景电解质溶液,研究了不同pH对分离己烯雌酚的影响。该方法被应用于测定己烯雌酚片剂中有效成分的含量。     

Gas chromatography of hydrocarbons using packed liquid chromatographic capillary columns

Capillary columns of 0.3-0.5 mm i.d. packed with 3- to 30-μm silica-based stationary phases for liquid chromatography were used for gas chromatographic separation of hydrocarbons. Column efficiencies were evaluated for various commercially available packing material. The best column efficiency was achieved with 5-μm octadecyl group bonded silica gel, the surface of which was coated with a poly (dimethylsiloxane) film. The 30-cm column produced 11,000 theoretical plates.     

Separation of PAHs in aerosol by thin layer chromatography for compound-specific stable carbon isotope analysis

A method using a thin layer chromatography (TLC) for compound-specific stable carbon isotope analysis of polycyclic aromatic hydrocarbons (PAHs) with four to seven rings was developed in this study. Five aerosol samples were used as test samples. Two stationary phases and eight developing systems were tested. The results indicated: (1) silica gel is superior to aluminum oxide and the silica gel precoated plate developed with hexane:chloroform (45:5, v/v) can give the best separation effect; (2) individual PAHs associated with aerosols can be effectively separated from unresolved complex mixture (UCM) by this procedure. The carbon isotope composition of PAHs can be measured with a standard deviation (S.D.) < 0.5‰, n = 4. No significant isotopic fractionation was observed during the TLC procedure. And this technique can be used as a potential tool for source identification of PAHs in the aerosols.     

Gas chromatography in open rectangular channels with large aspect ratios

Summary Gas chromatographic experiments have been performed in a truly rectangular channel with a 601 cross-sectional aspect ratio, constructed according to the field-flow fractionation technology. It is shown that the peak broadening is controlled by the thickness of the channel while the maximum load is determined by the largest cross-sectional dimension. However, even with its elongated configuration, the side walls contribute significantly to the band broadening of solutes with a high diffusivity. Good agreement is found between the experimental plate height data and the recent theoretical calculations of Golay [13] taking into account the side-wall effect.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Gas chromatography and gas chromatography/mass spectrometry for the characterization of complex mixtures of large oligosaccharides

High temperature gas chromatography and gas chromatography/mass spectrometry are used in the characterization of complex natural mixtures of permethylated oligosaccharides released from proteins or lipids. The high resolution allows separation of isomeric compounds and the mass range extends to oligosac-charides around molecular mass 2000 daltons or 10 sugar residues for isomalto-oligosaccharides. The mass spectra of permethylated oligosaccharide alditols from mucin glycopeptides are very informative and the approach allows a simple and rapid characterization of these complex components.     

Study on the photodegradation and microbiological degradation of pirimicarb insecticide by using liquid chromatography coupled with ion-trap mass spectrometry

The intermediates of photodegradation and microbial degradation of pirimicarb insecticide were investigated by liquid chromatography coupled with ion-trap mass spectrometry (LC–IT-MS). Different intermediates were detected in the photodegradation and microbial degradation of pirimicarb. In the photodegradation of pirimicarb in aqueous solution 2-dimethylamino-5,6-dimethyl-4-hydroxypyrimidine (MW = 167), 2-methylamino-5,6-dimethylpyrimidin-4-yl-dimethylcarbamate (MW = 224) and 2-formylamino-5,6-dimethylpyrimidin-4-yl-dimethylcarbamate (MW = 252) were the main products. It was found that 2-dimethylamino-5,6-dimethyl-4-hydroxypyrimidine (MW = 167) was the major product in the microbial degradation of pirimicarb in soil.     

Analysis of phthalides from umbelliferae by combined liquid-solid and gas-liquid chromatography

Summary A liquid-solid chromatographic pre-fractionation of naturally occurring phthalides has been developed. The LSC was carried out on a column of silica applying a 1–50% gradient elution of diethyl ether (containing 2% methanol) in pentane. The enrichment in the fractions led to better possibilities for a gas chromatographic separation and isolation allowing further studies by spectroscopic methods. Ligustilide may easily isomerize during GC as a result of ageing of the column.     

Gas chromatography with UV-vis molecular absorption spectrometry detection: Data acquisition and treatment when using a diode-array spectrophotometer

Summary This article describes a theoretical/practical study of the parameters which affect the chromatograms obtained when using a molecular diode-array spectrometer as the detector in gas chromatography. The objective is to offer some rules which permit the identification of the optimum signal/noise relation. To achieve this, we study the effect of the different parameters which affect the noise and how to reduce their impact, as well as alternatives for increasing the signal. All the options tested can be applied by correctly programming the spectrometer with BASIC programs, within reach of any use who has even a small understanding of programming. Finally, we consider the effect that the selection of the acquisition conditions may have on the chromatographic resolution. All the studies are carried out using a mixture of alcohols and phenols.     

Gas and liquid chromatography and enzyme linked immuno sorbent assay in pesticide monitoring of surface water from the western mediterranean (Comunidad Valenciana,Spain)

Summary A monitoring programme based on gas chromatography (NPD, ECD) using MSD for confirmatory purposes and coupled-column liquid chromatography was applied to the analysis of pesticide residues in surface water from a predominantly agricultural area of Spain (Comunidad Valenciana). Samples analysed by means of enzyme-linked immunosorbent assay gave similar results to those obtained by GC (MSD) for the determination of total triazines. The test employed had the advantages of a simple test procedure, short analysis time and high confirmatory value. Nevertheless, the multiresidue character, accuracy and unequivocal identification of individual pesticide residues of GC (MSD) make this technique the most appropriate for environmental monitoring programmes. In this monitoring programme about 200 samples were analysed between 1993–1994. 27 different pesticides were detected in 91 of these samples. The pesticides more frequently detected were dimethoate, methidathion, endosulfan A and B, endosulfan sulphate and pirimicarb. The highest concentrations found were 39.9 g L^–1 of dimethoate, 10.6 of pirimicarb and 10.6 of methidathion.