Gel Permeation Chromatography Calibration Research Articles

Universal calibration of gel permeation chromatography using evaporative light scattering detector coupled with viscometer

The linearized evaporative light scattering detector (ELSD) allows the evaluation of molecular weight distributions (MWD) of a range of polymers using conventional gel permeation chromatography (GPC), and is a suitable replacement for the differential refractive index (DRI) detector in applications which will benefit from fast equilibration, solvent gradients or when working with low polymer concentrations. Further, when DRI is coupled with a viscometer, the Universal Calibration GPC method also allows the evaluation of Mark–Houwink–Sakurada parameters K and alpha, which provides valuable information on the chemical structure of polymer chains. Therefore, for a wider acceptance of ELSD in GPC, we investigated the possibility of coupling the ELSD with the viscometer. Recommendations are provided for successfully coupling the ELSD and viscometer, as well as on software adjustments to calculate K and alpha parameters. For linear polyethylene, a good correlation was found between the measured and the expected K and alpha values.

Characterization of heavy crude oils and residues using combined Gel Permeation Chromatography and simulated distillation

Characterization of high molecular weight hydrocarbon mixtures such as heavy oil, bitumen, and vacuum residue is essential to design and optimization of the recovery, upgrading, and transportation processes. Characterization provides information about the boiling point and molecular weight distributions. To obtain these information, developing the simple, fast, and consistent characterization method is needed. In this work, for the first time, we combine Gel Permeation Chromatography (GPC) and Simulated Distillation (SD) results to characterize very heavy hydrocarbon samples. In the proposed characterization method, each sample is used individually as a standard sample for GPC calibration by properly matching SD and GPC results. In the other words, use of a standard sample, which is usually polymer compound and not appropriate representative for oil samples, is avoided. The GPC and SD results are coupled to generate the calibration curve that correlates the retention time and molecular weight. Employing the obtained calibration curve for each sample and having the GPC results, the whole molecular weight and boiling point distributions are obtained regardless of the complexity of the extra heavy sample. The proposed characterization method is validated using a known standard sample. Next, this method is applied to obtain molecular weight distribution of several bitumen samples and the bitumen fractions. The developed characterization method provides a tool to find a better understanding of the molecular weight and boiling point distributions of complex mixtures.

Molecular Weight Distribution of Low Molecular Weight Polyols Derived from Fatty Acid Methyl Esters

AbstractA series of commercial polyether polyols with well‐defined molecular weights (MW) was used along with propylene glycol and dipropylene glycol as gel permeation chromatography (GPC) calibration standards to determine the MW and oligomeric composition of the synthesized low MW fatty acid methyl ester (FAME) polyols, having an MW of lower than 600 Da. This GPC analysis was compared to the one calibrated against the commercially‐available polystyrene (PS) standards and to the number‐average molecular weight (Mn) obtained via vapor pressure osmometry (VPO) technique. The MW of FAME polyols obtained with GPC calibrated against polyether polyols were closer to the Mn values obtained via VPO than the MW obtained via GPC calibrated against PS standards. Using the reliable GPC calibration, the MW distribution and the hydroxyl functionality of FAME polyols were determined with greater confidence.

Polyether polyols as GPC calibration standards for determination of molecular weight distribution of polyether polyols

ABSTRACTAverage molecular weights (Mn,MwandMp) are important characteristics of oligomers and polymers, and therefore there is a need to have a precise and reliable determination method. A gel permeation chromatography (GPC) coupled with a single refractive index detector was used to determine the molecular weight distributions of commercial polyether polyols calibrated against a series of polyether polyols with known molecular weights and low polydispersity. Results of these GPC analyses were compared to the ones calibrated against the commercially available polystyrene (PS) standards. The number‐average molecular weights (Mn) obtained with GPC using polyether polyols calibration were closer to the theoretical values than theMnobtained using PS as calibration standards. Hence, these GPC analyses using polyether polyols as calibration standards can provide reliable determination of molecular weight distribution of polyether polyols and can be potentially applied to natural oil‐based polyols, including palm oil‐based polyols. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 42698.

Applicability of the modified universal calibration of gel permeation chromatography on proteins

The modified universal calibration of gel permeation chromatography (GPC) has been applied in the case of native proteins. Plotting log([ η] M/ Φ) versus elution volume, instead of log[ η] M versus elution volume used till now, we obtain unique curves with different proteins and non-proteonic polymers ([ η]: intrinsic viscosity, M: molecular mass, Φ: Flory's parameter). The values of Flory's parameter Φ are calculated for each protein using an indirect method based on GPC.

New way of presenting the universal calibration of gel permeation chromatography to include macromolecules with very high segment density

AbstractThe universal calibration of gel permeation chromatography presents deviations when star‐shaped polymers are used, especially when they present high segment density. Polymers presenting high segment density also have higher values of Flory's parameter Φ than the corresponding flexible, linear polymers. This deviation disappears if we express the hydrodynamic volume of the polymers with the quantity [η]M/Φ (where [η] is the intrinsic viscosity and M is the molecular mass) instead of the commonly used quantity [η]M. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2388–2391, 2005

Epoxidation of Polydienes Investigated by MALDI-TOF Mass Spectrometry and GPC-MALDI Coupling

Polybutadienes (PB) and polyisoprenes (PI) with various molecular weights and polydispersities were epoxidized applying two different synthetic routes. The degree of epoxidation was determined by means of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). It has been found that the degree of functionalization of polybutadiene is generally lower than that for polyisoprenes. Additionally, PB shows lower degrees of epoxidation at higher masses, whereas the level of functionalization of PI was unaffected by the molar mass. Coupling of gel permeation chromatography (GPC) with MALDI-TOF mass spectrometry was successfully used for the investigation of epoxidized polymers with higher masses. Using mass spectra of single fractions, the degree of epoxidation could be determined and applied for a calibration of GPC.

Gel permeation chromatography calibration based on fractal geometry

AbstractThe previously developed model [Polym Bull 2000, 44, 525] used to characterize the porous gel inside a gel permeation chromatography (GPC) column, has been extended to also include the interstitial space between the macroscopic gel particles. The hydrodynamic dimensions for 12 polystyrene (PS) standards, measured by GPC with differential refractive index (DRI), differential viscometry (VISCO), and multiangle laser light scattering (MALLS) detectors, have been used to determine the fractal parameters of the polystyrene–divinylbenzene gel corresponding to four commercial columns. The new developed model enables to predict the calibration curve for the sets of coupled columns based on the parameters of each column. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 771–777, 2004

Synthesis and characterization of novel aryl‐ethynylene polymers of tuned rigidity/flexibility

AbstractNew poly(aryl‐ethynylene) polymers of tuned rigidity/flexibility were synthesized by a palladium‐catalyzed polycondensation. The Sonogashira–Hagihara‐type coupling reaction of 2,5‐diethynyl‐4‐dodecyltoluene with 2,5‐ and/or 3,5‐dibromopyridine led to polymers of different rigidity/flexibility simply by varying the ratio of 2,5‐ to 3,5‐dibromopyridine charged in the polycondensation reaction. The ratio of para–meta linkages at the pyridine moiety in the polymer backbone was determined by NMR spectroscopy. The combination of molecular weight data obtained from vapor pressure osmometry and the use of oligomeric model compounds allowed us to establish a polymer‐specific gel permeation chromatography calibration. Information about the molecular conformation of the polymers in solution were obtained by small‐angle X‐ray scattering (SAXS) experiments. The glass‐transition and melting temperatures varied systematically with the degree of rigidity/flexibility and could be directly related to the conformational changes as reflected from the SAXS data. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1919–1933, 2004

Modification of the universal calibration of gel permeation chromatography to include macromolecules presenting a draining effect

AbstractA new universal calibration for gel permeation chromatography is proposed in which the hydrodynamic volume of the macromolecular chains is expressed by the quantity [η]M/Φ instead of the commonly used quantity [η]M (where [η] is the intrinsic viscosity, M is the molecular mass, and Φ is Flory's parameter). Introducing Φ into the hydrodynamic volume is necessary because its value changes from one polymer to another when the polymers present a certain draining effect. The proposed procedure also allows the determination of Φ of any wormlike polymer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 707–710, 2003

Characterization of bisphenol A-based epoxy resins by HPLC, GPC, GPC-MALLS, VPO, viscometry, and end group analysis: On the identification of 2,3-dihydroxypropyl-containing compounds, determination of molar mass distribution, and branching

Reversed-phase high performance liquid chromatography (HPLC), conventional gel permeation chromatography (GPC), and gel permeation chromatography coupled with a multiangle laser light scattering photometer (GPC–MALLS) were used for the analysis of epoxy resins based on bisphenol A. Compounds containing 2,3-dihydroxypropyl group were identified in HPLC chromatograms by means of the derivatization of sample by acetone. The presence of branched molecules was proved by GPC–MALLS using a molar mass versus root mean square (RMS) radius plot or molar mass versus elution volume plot. The molar mass distribution determined by HPLC was compared with that obtained by GPC–MALLS. Molar mass averages measured by means of GPC, GPC–MALLS, vapor pressure osmometry (VPO), and end group analysis (EG) were compared and the differences of results obtained by particular methods were discussed. An appropriate GPC calibration was found on the basis of literature data and the comparison of molar mass averages measured by GPC, VPO, and GPC–MALLS. The refractive index increment of epoxy resins was determined. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2432–2438, 1999

Characterization of Anadenanthera macrocarpa exudate polysaccharide

Exudate gum from Anadenanthera macrocarpa Benth. trees was purified and fractionated using 0·1M aq. NaCl/ethanol as a solvent/non-solvent system. The composition of the polysaccharide was determined as 67% arabinose, 24% galactose, 2% rhamnose and 7% glucuronic acid, by a combination of high performance liquid chromatography of fully hydrolysed gum and colorimetric analysis of uronic acid. Molecular characteristics of the polysaccharide and its fractions were investigated by light scattering intensity, dilute solution visco-metry and gel permeation chromatography (GPC). The whole gum was shown to possess a broad molar mass distribution with Mw = 3·7×106 g mol-1 and [η] = 11cm3 g-1. Hydrodynamic properties indicated a highly branched structure. Fractions were obtained covering a range of molar masses. The intrinsic viscosity in 1·0 M aq. NaCl at 25°C was found to depend on molar mass according to: [η]/cm3 g-1 =0 ·0145 M0·44. The hydrodynamic volume parameter [η]M gave a common GPC calibration for branched polysaccharide fractions and linear poly(oxyethylene) standards. ©1997 SCI

Characterization ofAnadenanthera macrocarpa exudate polysaccharide

Exudate gum from Anadenanthera macrocarpa Benth. trees was purified and fractionated using 0.1 M aq. NaCl/ethanol as a solvent/non-solvent system. The composition of the polysaccharide was determined as 67% arabinose, 24% galactose, 2% rhamnose and 7% glucuronic acid, by a combination of high performance liquid chromatography of fully hydrolysed gum and colorimetric analysis of uronic acid. Molecular characteristics of the polysaccharide and its fractions were investigated by light scattering intensity, dilute solution viscometry and gel permeation chromatography (GPC). The whole gum was shown to possess a broad molar mass distribution with Mw = 3.7 x 10 6 g mol -1 and [η] = 11 cm 3 g -1 . Hydrodynamic properties indicated a highly branched structure. Fractions were obtained covering a range of molar masses. The intrinsic viscosity in 1.0 M aq. NaCI at 25°C was found to depend on molar mass according to: [η]/cm 3 g -1 = 0.0145 M 0.44 . The hydrodynamic volume parameter [η]M gave a common GPC calibration for branched polysaccharide fractions and linear poly(oxyethylene) standards.

Perspective: Comments on “A universal calibration for gel permeation chromatography,” by Z. Grubisic, P. Rempp, and H. Benoit,J. Polym. Sci., 5, 753 (1967)

Perspective: Comments on “A universal calibration for gel permeation chromatography,” by Z. Grubisic, P. Rempp, and H. Benoit,J. Polym. Sci., 5, 753 (1967)

Commentary: Reflections on “A universal calibration for gel permeation chromatography,” by Z. Grubisic, P. Rempp, and H. Benoit,J. Polym. Sci., 5, 753 (1967)

Commentary: Reflections on “A universal calibration for gel permeation chromatography,” by Z. Grubisic, P. Rempp, and H. Benoit,J. Polym. Sci., 5, 753 (1967)

Studies on microgels, 1. Microgel formation studied by gel‐permeation chromatography with an on‐line light scattering detector

AbstractThe previously described microgel synthesis in which living poly(4‐tert‐butylstyrene) was reacted with 1,4‐divinylbenzene was studied. Samples were taken after the addition of the crosslinker and characterized by gel‐permeation chromatography (GPC) with an on‐line multi angle laser light scattering (MALLS)‐ and a differential refractive index (DRI) detector. Primary particle formation was found early in the reaction followed by interparticular crosslinking. The GPC calibration curves allowed the derivation of a branching plot. The branching plots showed, that in addition to interparticular crosslink reactions also intraparticular crosslink reactions are occurring. The plots also showed that the primary particles scale like linear polymers, which led to the conclusion that they consist of comb‐like structures with poly(4‐vinylstyrene) as the backbone and poly(4‐tert‐butylstyrene) as branches.

Liquid chromatographic analysis of cationic polymerized phenyl glycidyl ether

Products of cationic polymerization of phenyl glycidyl ether were analysed by gel permeation chromatography and high-performance liquid chromatography. Individual oligomers were isolated by semipreparative high-performance liquid chromatography for the purposes of identification by mass spectrometry and gel permeation chromatography calibration. An equation for the conversion of the molecular weight of oligostyrene to that of oligophenyl glycidyl ether was derived. This equation was used for the determination of oligophenyl glycidyl ether molecular weight distribution by gel permeation chromatography. Molecular weight distribution curves of oligophenyl glycidyl ether samples were determined by high-performance liquid chromatography and gel permeation chromatography and compared.

Application of universal calibration in gel permeation chromatography for molecular weight determinations of plant cell wall polymers: cotton fiber

Methodology has been established to determine the molecular weight distribution of the cellulosic composition of cotton fibers without prior extraction or derivatization, processes that can degrade polymers. Dimethylacetamide with lithium chloride is used for the dissolution of samples.

Poly(isoprene-g-alkyl methacrylate) copolymers: 1. Poly(alkyl methacrylates) with azodicarboxylate end groups

Synthesis of four poly(alkyl methacrylates) having different ester alkyl chain lengths (butyl-, hexyl-, dodecyl- and octadecyl-) and azodicarboxylate end groups is described. The molecular weights of the polymers are in the range 5 × 10 3–1 × 10 4, and between 60 and 70% of the polymer chains have azodicarboxylate functionality. Radical transfer constants for the alkyl methacrylates with 2-mercaptoethanol in benzene solution at 60°C are reported together with Mark—Houwink K and a constants required for gel permeation chromatography calibration.

Universal calibration of gel permeation chromatography and determination of molecular shape in solution

Gel permeation chromatography (GPC) has become a routine technique for both biology and polymer chemistry. By comparison our theoretical perception of the separation principle of GPC is still immature and conflicting and so is the assessment of the analytical informational content of this method. In order to discriminate between the various parameters that might influence GPC and thus to decide among the numerous propositions of calibration, several odd biopolymers (tropomyosin, spectrin, DNA, tobacco mosaic virus, α-actinin, ovomucoid) were selected. They were characterized by analytical ultracentrifugation as well as quasielastic light scattering, and they were compared to globular proteins including icosahedral viruses (tomato bushy stunt virus, turnip yellow mosaic virus, Qβ, MS2) on several different HPLC column matrices. The results demonstrate that the universal calibration principle of GPC is the viscosity radius, i.e., the molecular volume times a shape function which is defined by the intrinsic viscosity. Alternate propositions such as molecular weight, second virial coefficient, diffusion coefficient (Stokes radius), radius of gyration, mean linear projected length, contour length, and related measures seem to be excluded on the basis of the evidence presented. These results help to focus the physical picture which seems to govern GPC. Finally it is demonstrated that GPC is a versatile and unique tool with which to characterize molecular shape and dynamics in solution.