Pattern recognition for identification and quantitation of complex mixtures in chromatography

Lea, Robert E.; Bramston-Cook, Randall; Tschida, J.

doi:10.1021/ac00255a010

Anal. Chem.

1983

DOI: 10.1021/ac00255a010

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Pattern recognition for identification and quantitation of complex mixtures in chromatography

Robert E. Lea¹,

Randall Bramston-Cook²,

J. Tschida³

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1985

2005

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Cited by 20 publications

(3 citation statements)

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“…However, the attitude to this problem has changed in recent years because the inappropriately great consumption of time at this stage or the high cost of these samples can make unreasonable the performance of the analysis in general [4][5][6][7][8]. First is the problem of finding ana-lyte reference samples, long considered as insignificant and completely irrelevant to quantitative analysis.…”

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confidence: 99%

Characterization of the interlaboratory reproducibility of results in quantitative gas-chromatographic analysis using the internal normalization method

2005

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A comparison of the results of gas-chromatographic analysis performed for the same samples with the use of various instruments with flame-ionization detectors and different (packed and capillary) columns indicates statistically significant differences in the results of data processing by the internal normalization method. Such variations in relative peak areas were detected on the same instrument on a comparison between data obtained under isothermal conditions and with temperature programming. Conceivable reasons for the observed changes in relative peak areas and procedures for the evaluation of errors due to this effect in the analysis of various samples on particular instruments are considered.

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confidence: 99%

Characterization of the interlaboratory reproducibility of results in quantitative gas-chromatographic analysis using the internal normalization method

2005

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“…First is the problem of finding analyte reference samples, long considered as insignificant and completely irrelevant to quantitative analysis. However, the attitude to this problem has changed in recent years because the inappropriately great consumption of time at this stage or the high cost of these samples can make unreasonable the performance of the analysis in general [4][5][6][7][8]. Second, various procedures for the theoretical evaluation of relative detector sensitivity coefficients to various compounds based on the composition (or, more rarely, the structure) of analytes [1, vol.…”

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Characterization of the interlaboratory reproducibility of results in quantitative gas-chromatographic analysis using the internal normalization method

Зенкевич¹,

Eshchenko²,

Klimova³

2005

J Anal Chem

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A complete chromatographic analysis usually implies the identification and quantitative determination of the concentrations of all or only particular target components in test samples. To solve the latter problem, various quantitative methods of analysis are used; these differ in sample preparation and data processing techniques [1,2]. The most accurate versions of determination imply the availability of certified reference materials, which are required for the preparation of calibration mixtures (absolute calibration and external standard techniques); the direct addition to test samples (standard addition); or the predetermination of the calibration coefficients ( f i ) expt of the target components with reference to standard substances chosen (internal standard and internal normalization). In the absence of reference samples, quantitative analysis is usually restricted to the use of only external and internal standards or internal normalization on the condition that the chromatographic relative sensitivity coefficients ( f i ) calcd for various compounds were theoretically precalculated. In the presentation of analytical results obtained for chemically similar substances by the internal normalization method with the use of flame-ionization detectors (FIDs), it is often assumed that f i ≡ const. The same approach (the calculation of relative peak areas) is used in processing analytical results obtained by chromatography-mass spectrometry in multicomponent mixtures, although the ionization cross sections of various organic compounds are dramatically different [3].Two objective causes are responsible for such a reduction in the requirements imposed on the results of the quantitative determination of the composition of complex samples. First is the problem of finding analyte reference samples, long considered as insignificant and completely irrelevant to quantitative analysis. However, the attitude to this problem has changed in recent years because the inappropriately great consumption of time at this stage or the high cost of these samples can make unreasonable the performance of the analysis in general [4][5][6][7][8]. Second, various procedures for the theoretical evaluation of relative detector sensitivity coefficients to various compounds based on the composition (or, more rarely, the structure) of analytes [1, vol. 2, p. 173; 7] give only estimated values of ( f i ) calcd , usually without estimated errors; in particular, they do not reflect the known effects of analytical conditions on the values of ( f i ) expt .The effects of conditions (detector geometry, flame temperature, carrier gas, etc.) were characterized in the greatest detail for the absolute characteristics of FID sensitivity [1]. However, variations in the relative values ( f i ) expt were usually considered to be comparatively small, and they were ascribed to the random component of determination errors. For this reason, specific features of data processing by the internal normalization method were not related to the temperature conditions of...

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“…It is illustrated by comparing essential oils from different sources and detecting essential oils in complex mixtures. This method should be also useful in the study of many other types of mixtures, such as biomedical fluids (1, 2), environmental pollutants (3)(4)(5), and natural products (6).…”

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Analysis of complex mixtures by gas chromatography/mass spectrometry using a pattern recognition method

Chien¹

1985

Anal. Chem.

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the volatile trimethyl borate by codistillation with methanol, and the residue was heated 2 h at 85 "C, in vacuo to completely convert the aldonic acids into aldonolactones. Lower temperatures and/or shorter time periods resulted in partial conversion and the isolation of some free aldonic acids. Complete conversion is necessary because aldonic acids will not form N-propylaldonamide when treated with l-propylamine. Even though the amine is very basic, it did not cause epimerization under the conditions studied. Acetylation with pyridine and acetic anhydride requires 1 h and is quantitative. Dehydration reactions occur with the lactone (16) but not with the amide.Essentially the original aldoses have been converted into alditol acetates, and the original aldonic acids and aldonolactones have been converted into corresponding N-propylaldonamides. Calibration curves constructed by plotting detector response vs. milligrams of sample (1.2-6.7 mg) have a correlation coefficient greater than 0.995. A wider range of sample sizes can be accommodated by suitable concentration or dilution of the injected sample.There are a number of advantages to the new procedure. The method is able to handle complex mixtures of aldonic acids and aldoses. Alduronic acids can be determined by suitable modifications. Because the carboxyl group is kept, the stereochemical configuration of the sugar is maintained, unlike the differential method (2) wherein the lactone is reduced to the alditol. The new method adds a degree of versatility not found in most methods. The N-propyl group can be substituted easily by an N-butyl, N-amyl, or even an N-hexyl by replacing 1-propylamine by some other amine. The lactone will react under basically the same conditions to give a homologous derivative. The advantages are readily apparent in that the larger the N-alkyl group, the greater the elution time relative to the alditols or other possible compo-nents, e.g., phenyl P-D-ghcopyranoside. In fact, N-propylxylonamide coelutes with phenyl 0-D-glucopyranosides; by changing to N-amylamine, one is able to separate them into two peaks while maintaining the resolution seen in Figure 2. (5) Dmitriev, B. A.; Backinowsky, L. V.; Chizhov, 0. S.; Zoiotarev, 8. M.; Kochetkov, N. K. Analysis of a complex mlxture Involves a gas chromatographlc separation followed by a mass spectral search for Identification of each component. Thls Is an extremely tedlous andtime-consumlng process for fragrances and flavors whlch sometimes contaln hundreds of components. Thls presentatlon describes a computer pattern recognttlon method for the rapid ldentlficatlon of components in a complex mixture, the comparlson between the complete GC profiles of different samples, and the recognltlon of a group of compounds as a single entity. The central part of thls method is a comparlson algorlthm which compares the components In two mixtures uslng the K nearest neighbor classification rule. I t is Illustrated by comparing essential oils of dlfferent sources and by detectlng essentlal 011s In perfum...

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Pattern recognition for identification and quantitation of complex mixtures in chromatography

Cited by 20 publications

References 2 publications

Characterization of the interlaboratory reproducibility of results in quantitative gas-chromatographic analysis using the internal normalization method

Characterization of the interlaboratory reproducibility of results in quantitative gas-chromatographic analysis using the internal normalization method

Characterization of the interlaboratory reproducibility of results in quantitative gas-chromatographic analysis using the internal normalization method

Analysis of complex mixtures by gas chromatography/mass spectrometry using a pattern recognition method

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