Gel permeation chromatography high pressure

Cleanup or fractionation procedures that have been used in the more recent fat-soluble vitamin assays include sterol precipitation, open-column chromatography, solid-phase extraction, and high-pressure gel permeation chromatography. High-performance LC has been used on a semipreparative scale in vitamin D and vitamin K assays to obtain purified fractions of sample extracts. This technique is discussed in Sec. V.B.3. 

High-pressure gel permeation chromatography (pStyragel columns eluted with dichloromethane or tetrahydrofuran) has been used for preliminary purification of retinyl palmitate in foodstuffs (128,129) but has not gained wide usage. 

The sample preparation has been carried out at ambient pressure and temperature. The properties of the PEP-polymers used for the cloud-point measurements are listed in Table 8.1, for which the molecular weights have been measured with high temperature gel permeation chromatography (GPC, dynamic viscosity). The estimated relative error in the amounts of the components in the mixtures is <2% for PEP8.7, <0.1% for PEP51 and ethylene, and <0.7% for CO2. 

To ensure quality control material suppliers and developers routinely measure such complex properties as molecular weight and its distribution, crystallinity and crystalline lattice geometry, and detailed fracture characteristics (Chapter 6). They use complex, specialized tests such as gel permeation chromatography (2, 3), wide- and narrow-angle X-ray diffraction, scanning electron microscopy, and high-temperature pressurized solvent reaction tests to develop new polymers and plastics applications. 

Analysts. It has been our objective to determine criteria for resin, curative or formulation which would permit prediction of sucess prior to potting tests. Many tests, both chemical and physical in nature, have been executed on commercial resin systems. These have included high pressure liquid chromatography (HPLC), Fourier Transform infrared spectrometry (FTIR), gel permeation chromatography, compressive tensile tests by Instron on resin plaques in air and under various aqueous solutions and heat distortion temperature. 

WO Landen Jr, RR Eitenmiller. Application of gel permeation chromatography and nonaqueous reverse phase chromatography to high pressure liquid chromatographic determination of retinyl palmitate and /3-carotene in oil and margarine. J Assoc Off Anal Chem 62 283-289, 1979. 

Gel Permeation Chromatography (GPC) GPC of all samples were recorded with a Waters Associates Model 244 high-pressure liquid chromatograph using a dilute solution (0.02% in tetrahydrofuran and a flow rate of 5 ml/min). The chromatograph was connected with four microstyragel columns in series (pore size 10 , 10 ,... 

Analyses of Pitch. Modern analytical facilities of high-pressure liquid chromatography, gel permeation chromatography, an(j 1 nuclear magnetic resonance and mass spectrometry, associated with 1R and UV spectroscopy enable a total molecular constituent analysis of pitch composition to be obtained. The use of such information could then possibly be the route to prediction of pitch quality on carbonization. It would appear that such an approach would not be successful (ignoring the cost factor for such detailed analysis). The pitch cannot be considered as an assembly of molecules which pyrolyse independently of each other. The pitch carbonizes as a multi-phase system and experience today would indicate the impossibility of predicting all interactions, physical and chemical. 

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