PCB separation by HRGC‐MS. Fourier analysis for characterizing Aroclor chromatograms

Pietrogrande, Maria Chiara; Pasti, Luisa; Dondi, Francesco; Rodriguez, M. H. Bollain; Diaz, Maria A. Carro

doi:10.1002/jhrc.1240171207

Cited by 33 publications

(25 citation statements)

References 37 publications

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“…To speed up the computations, these average concentrations were evaluated by interpolating values of the error function evaluated for arguments spaced by 0.001 and not by numerical integration as before [15]. Exponentially random peak heights were used because they have some empirical basis [20-23]. The sampled concentrations were “injected” into the second dimension as Gaussians having standard deviations calculated from the relevant peak capacity using Eq.…”

Section: Methodsmentioning

confidence: 99%

Dependence of Effective Peak Capacity in Comprehensive Two-Dimensional Separations on the Distribution of Peak Capacity between the Two Dimensions

2008

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One of the basic tenets of comprehensive two-dimensional chromatography is that the total peak capacity is simply the product of the first and second dimension peak capacities. As formulated the total peak capacity does not depend on the relative values of the individual dimensions but only on the product of the two. This concept is tested here for the experimentally realistic situation wherein the first dimension separation is undersampled. We first propose that a relationship exists between the number of observed peaks in a two-dimensional separation and the effective peak capacity. We then show here for a range of reasonable total peak capacities (500 to 4000) and various contributions of peak capacity in each dimension (10 to 150) that the number of observed peaks is only slightly dependent on the relative contributions over a reasonable and realistic range in sampling times (equal to the first dimension peak standard deviation, multiplied by 0.2 to 16). Most of this work was carried out under the assumption of totally uncorrelated retention times. For uncorrelated separations the small deviations from the product rule are due to the “edge effect” of statistical overlap theory and a recently introduced factor that corrects for the broadening of first dimension peaks by undersampling them. They predict that relatively more peaks will be observed when the ratio of the first to the second dimension peak capacity is much less than unity. Additional complications are observed when first and second dimension retention times show some correlation but again the effects are small. In both cases deviations from the product rule are measured by the relative standard deviations of the number of observed peaks, which are typically 10 or less. Thus although the basic tenet of two-dimensional chromatography is not exact when the first dimension is undersampled, the deviations from the product rule are sufficiently small as to be unimportant in practical work. Our results show that practitioners have a high degree of flexibility in designing and optimizing experimental comprehensive two-dimensional separations.

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Section: Methodsmentioning

confidence: 99%

Dependence of Effective Peak Capacity in Comprehensive Two-Dimensional Separations on the Distribution of Peak Capacity between the Two Dimensions

2008

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“…The first is qualitative and enables one to single out any recursive structures within the chromatogram. This approach has been applied to chromatograms of naphtha and Aroclors [20,22]. The second, specifically considered here, is a method by which intrinsic at- tributes can be evaluated [16-20, 22, 24].…”

Section: The Simplified Procedures For Obtaining Intrinsic Attributesmentioning

confidence: 99%

Decoding complex multicomponent chromatograms by fourier analysis

1997

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SummaryThe present work discusses the many attributes -classified as observable, intrinsic or hidden -which can be conceived for any complex multicomponent chromatogram. Discussion ensues on how to decode such chromatograms, i.e. determining the intrinsic and/or hidden attributes from those which can be observed. There are two main steps. The first is based on Fourier Analysis (FA) and determines the intrinsic attributes: i.e., the number of single components which can be detected; their distribution over the available chromatographic space and peak capacity. The second evaluates the hidden attributes: i.e., the effects of incomplete separation, the number of peaks created by one or more single components as well as their degree of purity. The hidden attributes can be obtained by applying the theory of Statistical Degree of peak Overlapping (SDO) and the paper goes into the extent to which the SDO step depends on the FA results. In addition, the role Exponential distribution plays as a point of reference for the distribution of both single component peak position interdistances and peak heights is discussed. Finally, a simplified graphical FA procedure is presented and the main achievements in this field are reviewed.

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“…An off-line LC-GC procedure was used for Aroclor 1242 and 1254 mixtures to enable use of GC-MS for separation and identification of congener structures [1,23,24]. For each Aroclor mixture a 10-1xL sample of a 500-ppm solution was fractionated in the HPLC apparatus.…”

Section: Off-line Lc-gc Proceduresmentioning

confidence: 99%

Analysis of PCB by on-line coupled HPLC-HRGC

et al. 2002

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On-line coupled HPLC-GC has been used for the fractionation and analysis of polychlorobiphenyls (PCB) according to their planarity. HPLC elution with porous graphitic carbon (PGC) as stationary phase, enables fractionation of PCB into classes according to the amount of ortho-substitution, which is related to congener toxicity. This is a preliminary step before GC analysis, which enables complete separation of PCB congeners according to vapour pressure. Conditions for HPLC-HRGC coupling were optimised, in particular the appropriate proper HPLC solvent was selected, because it determines eluent strength and selectivity and the transfer conditions. Different solvents were studied -n-hexane, dichloromethane, benzene, toluene, and their mixtures.Samples containing PCB standards and the commercial mixtures Aroclor 1242 and 1254 were analysed. Dichloromethane-n-hexane, 1 : 1, was selected as mobile phase for separation of poly-ortho from mono-ortho PCB; benzene-dichloromethane 30:70 resulted in the best separation of the most retained non-ortho-substituted PCB. Under these conditions the co-solvent trapping procedure, performed by adding 4% ethylbenzene as co-solvent, was used as transfer technique to overcome the drawback of losses of volatile congeners.Appropriate analysis conditions were successfully used to fractionate the technical PCB for-mulationsAroclor

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PCB separation by HRGC‐MS. Fourier analysis for characterizing Aroclor chromatograms

Cited by 33 publications

References 37 publications

Dependence of Effective Peak Capacity in Comprehensive Two-Dimensional Separations on the Distribution of Peak Capacity between the Two Dimensions

Dependence of Effective Peak Capacity in Comprehensive Two-Dimensional Separations on the Distribution of Peak Capacity between the Two Dimensions

Decoding complex multicomponent chromatograms by fourier analysis

Analysis of PCB by on-line coupled HPLC-HRGC

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