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Chromatographic analysis

To estimate the effect of automobile traffic and motor fuels on ozone formation, it is necessary to know the composition of exhaust gas in detail. Figure 5.26 gives an example of a gas phase chromatographic analysis of a conventional unleaded motor fuel. [Pg.262]

Wilcoxon J P and Craft S A 1997 Liquid chromatographic analysis and characterization of inorganic nanoclusters Nanostruct. Mater. 9 85... [Pg.2919]

The reaction product is cooled to room temperature, is washed with 10 ml of H2O to the purpose of removing lithium iodide and is then dehydrated over NaiS04. 3.57 g is obtained of dimethoxy-phenylacetone (III), as determined by gas-chromatographic analysis with an inner standard of 4,4 -dimethoxybeniophenone. The yield of ketone (III) relative to the olefin ( ) used as the starting material is of 87.1%. [Pg.190]

Two examples from the analysis of water samples illustrate how a separation and preconcentration can be accomplished simultaneously. In the gas chromatographic analysis for organophosphorous pesticides in environmental waters, the analytes in a 1000-mL sample may be separated from their aqueous matrix by a solid-phase extraction using 15 mb of ethyl acetate. After the extraction, the analytes are present in the ethyl acetate at a concentration that is 67 times greater than that in... [Pg.223]

In a chromatographic analysis of lemon oil a peak for limonene has a retention time of 8.36 min with a baseline width of 0.96 min. y-Terpinene elutes at 9.54 min, with a baseline width of 0.64 min. What is the resolution between the two peaks ... [Pg.549]

In a chromatographic analysis of low-molecular-weight acids, butyric acid elutes with a retention time of 7.63 min. The column s void time is 0.31 min. Calculate the capacity factor for butyric acid. [Pg.552]

In the same chromatographic analysis for low-molecular-weight acids considered in Example 12.2, the retention time for isobutyric acid is 5.98 min. What is the selectivity factor for isobutyric acid and butyric acid ... [Pg.552]

A chromatographic analysis for the chlorinated pesticide Dieldrin gives a peak with a retention time of 8.68 min and a baseline width of 0.29 min. How many theoretical plates are involved in this separation Given that the column used in this analysis is 2.0 meters long, what is the height of a theoretical plate ... [Pg.554]

Precision The precision of a gas chromatographic analysis includes contributions from sampling, sample preparation, and the instrument. The relative standard deviation due to the gas chromatographic portion of the analysis is typically 1-5%, although it can be significantly higher. The principal limitations to precision are detector noise and the reproducibility of injection volumes. In quantitative work, the use of an internal standard compensates for any variability in injection volumes. [Pg.577]

The following data have been reported for the gas chromatographic analysis of p-xylene and methylisobutylketone (MIBK) on a capillary column. ... [Pg.617]

Table 4. Gas Chromatographic Analysis of the Results of Cracking Polymer Mixtures Using a Conrad Unit ... Table 4. Gas Chromatographic Analysis of the Results of Cracking Polymer Mixtures Using a Conrad Unit ...
The comonomer content of copolymers may be estimated by nmr or by controlled solvolysis of the copolymer followed by quantitative chromatographic analysis of the residues. [Pg.58]

In current industrial practice gas chromatographic analysis (glc) is used for quahty control. The impurities, mainly a small amount of water (by Kad-Fischer) and some organic trace constituents (by glc), are deterrnined quantitatively, and the balance to 100% is taken as the acetone content. Compliance to specified ranges of individual impurities can also be assured by this analysis. The gas chromatographic method is accurately correlated to any other tests specified for the assay of acetone in the product. Contract specification tests are performed on product to be shipped. Typical wet methods for the deterrnination of acetone are acidimetry (49), titration of the Hberated hydrochloric acid after treating the acetone with hydroxylamine hydrochloride and iodimetry (50), titrating the excess of iodine after treating the acetone with iodine and base (iodoform reaction). [Pg.98]

Monobasic acids are determined by gas chromatographic analysis of the free acids dibasic acids usually are derivatized by one of several methods prior to chromatographing (176,177). Methyl esters are prepared by treatment of the sample with BF.—methanol, H2SO4—methanol, or tetramethylammonium hydroxide. Gas chromatographic analysis of silylation products also has been used extensively. Liquid chromatographic analysis of free acids or of derivatives also has been used (178). More sophisticated hplc methods have been developed recentiy to meet the needs for trace analyses ia the environment, ia biological fluids, and other sources (179,180). Mass spectral identification of both dibasic and monobasic acids usually is done on gas chromatographicaHy resolved derivatives. [Pg.246]

Bromine ttifluoride is commercially available at a minimum purity of 98% (108). Free Br2 is maintained at less than 2%. Other minor impurities are HF and BrF. Free Br2 content estimates are based on color, with material containing less than 0.5% Br2 having a straw color, and ca 2% Br2 an amber-red color. Fluoride content can be obtained by controlled hydrolysis of a sample and standard analysis for fluorine content. Bromine ttifluoride is too high boiling and reactive for gas chromatographic analysis. It is shipped as a Hquid in steel cylinders in quantities of 91 kg or less. The cylinders are fitted with either a valve or plug to faciUtate insertion of a dip tube. Bromine ttifluoride is classified as an oxidizer and poison by DOT. [Pg.187]

This represents the first large-scale appHcation of a fluoroaryl organometaOic. Other silicon-containing aryl fluorides such as pentafluorophenyldimethyl silanes, CgF Si(CH2)2X (X = Cl NH2 N(0211 )2), are offered commercially as Flophemsyl reagents for derivati2ation of sterols in chromatographic analysis (166). [Pg.322]

Other Methods. Ion chromatography using conductance detection can be used to measure low (<1%) levels of nitrite, chloride, sulfate, and other ions in nitric acid. Techniques for ion chromatographic analysis are available (93). [Pg.47]

Solvent extraction followed by gas chromatographic analysis is used to determine paraffin wax antioxidants (qv), ie, butylated hydroxyanisole and butylated hydroxytoluene and other volatile materials. Trace amounts of chlorinated organic compounds, eg, polychlorinated biphenyls, can be deterrnined by using a gas chromatograph with an electron-capture detector (22). [Pg.11]

Concretes and absolutes, both obtained by total extraction of the plant material and not subject to any form of distillation other than solvent removal, are complex mixtures containing many chemical types over wide molecular weight ranges. In some cases, gas chromatographic analysis shows httle volatile material. Yet these products have powerful odors and contribute in important ways to the perfumes in which they are used. [Pg.76]

ASTM Standard E 475-84, "Standard Test Method for Assay of Di-fetf-Butyl Peroxide by Gas Chromatographic Analysis," in Ref. 253. [Pg.139]

The synthesis and the quantitative gas chromatographic analysis of stable, yet volatile, A/-trifluoroacetyl- -butyl esters of amino acids has been estabhshed (124). An extensive review of subsequent advances ia gas chromatographic iastmmentation has been provided (125). [Pg.285]

Analytical Methods. A method has been described for gas chromatographic analysis of trichloromethanesulfenyl chloride as well as of other volatile sulfur compounds (62). A method has been recommended for determining small amounts of trichloromethanesulfenyl chloride in air or water on the basis of a color-forming reaction with resorcinol (63). [Pg.132]

M. H. Bui-Nguyen, in A. P. DeLeenheer, eds.. Modem Chromatographic Analysis of the Vitamins, Marcel Dekker, New York, 1985, Chapt. 5. [Pg.24]

The identification of benzene is most easily carried out by gas chromatography (83). Gas chromatographic analysis of benzene is the method of choice for determining benzene concentrations in many diverse media such as petroleum products or reformate, water, sod, air, or blood. Benzene in air can be measured by injection of a sample obtained from a syringe directiy into a gas chromatograph (84). [Pg.46]

Several quantitative procedures for concentrations above 0.1 vol % are available. Gas chromatographic analysis (78) is particularly useful because it is fast, accurate, and relatively inexpensive. The standard wet-chemical, analytical method (76) takes advantage of the reaction between iodine pentoxide and carbon monoxide at 423 K. [Pg.53]

A method of resolution that makes a very few a priori assumptions is based on principal components analysis. The various forms of this approach are based on the self-modeling curve resolution developed in 1971 (55). The method requites a data matrix comprised of spectroscopic scans obtained from a two-component system in which the concentrations of the components are varying over the sample set. Such a data matrix could be obtained, for example, from a chromatographic analysis where spectroscopic scans are obtained at several points in time as an overlapped peak elutes from the column. [Pg.429]

Purity. Gas chromatographic analysis is performed utilizing a wide-bore capillary column (DB-1, 60 m x 0.32 mm ID x 1.0 //m film) and a flame ionization detector in an instmment such as a Hewlett-Packard 5890 gas chromatograph. A caUbration standard is used to determine response factors for all significant impurities, and external standard calculation techniques are used to estimate the impurity concentrations. AHyl chloride purity is deterrnined by difference. [Pg.35]

The side-chain chlorine contents of benzyl chloride, benzal chloride, and benzotrichlorides are determined by hydrolysis with methanolic sodium hydroxide followed by titration with silver nitrate. Total chlorine determination, including ring chlorine, is made by standard combustion methods (55). Several procedures for the gas chromatographic analysis of chlorotoluene mixtures have been described (56,57). Proton and nuclear magnetic resonance shifts, characteristic iafrared absorption bands, and principal mass spectral peaks have been summarized including sources of reference spectra (58). Procedures for measuring trace benzyl chloride ia air (59) and ia water (60) have been described. [Pg.61]

Chromatography is a technique for separating and quantifying the constituents of a mixture. Separation techniques are essential for the characterization of the mixtures that result from most chemical processes. Chromatographic analysis is used in many areas of science and engineering in environmental studies, in the analysis of art objects, in industrial quahty control (qv), in analysis of biological materials, and in forensics (see Biopolymers, analytical TECHNIQUES FiNE ART EXAMINATION AND CONSERVATION FoRENSic CHEMISTRY). Most chemical laboratories employ one or more chromatographs for routine analysis (1). [Pg.104]

Time-Delay Compensation Time delays are a common occurrence in the process industries because of the presence of recycle loops, fluid-flow distance lags, and dead time in composition measurements resulting from use of chromatographic analysis. The presence of a time delay in a process severely hmits the performance of a conventional PID control system, reducing the stability margin of the closed-loop control system. Consequently, the controller gain must be reduced below that which could be used for a process without delay. Thus, the response of the closed-loop system will be sluggish compared to that of the system with no time delay. [Pg.733]

This matrix will necessarily be sparse. First, not all measurements can be taken for a given stream or position (e.g., a chromatographic analysis may only measure a subset of the component compositions). Second, not all streams or positions are included. Third, some of the measurements are inadequate due to bias and are discarded. [Pg.2560]

The methods, which allow in one procedure of analysis to overcome, for example, most pesticides which are used in agricultural practice in the present time, get development and introduction in practice. The contribution of the Ukrainian scientists in field of chromatographic analysis of Persistent Organic Pollutants (POPs, chlorinated hydrocarbons, PCB s) and supertoxicants, such as PCDDs, is estimated. [Pg.65]

Interaction of formaldehyde with 2,4-dinitrophenylhydrazine in acid media causes 2,4-dinitrophenylhydrazone (DNPhydrazone) formaldehyde formation. Gas-chromatographic analysis of 2,4-DNP-hydrazone formaldehyde toluene extract with an electron holding detector makes it possible to detect it at the level of 0,001 mg/dm. Phenol is detected in the form of tribromphenol yield, the hexane extract of which undergoes chromatography with an electron holding detector which provides the level of phenol detection of 0.001 mg/dm (the limit of quantitative detection). [Pg.389]


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