Tetrahydrofuran polystyrene standards

FIGURE 4.38 Calibration curves for TSK-GEL Hxl columns with polyst/rene standards. Column TSK-GEL Hxl series, two 7.8 mm x 30 cm columns in series. Sample Polystyrene standards. Elution Tetrahydrofuran. Flow rate 1.0 ml/min. Detection Rl. 

The ISO method prescribes polystyrene standards with tetrahydrofuran as the eluent, but this equation can also be used with other narrow distribution standards, provided the same elution solvent and the same standards are used for a comparison. Further, the ISO method requires the result to be greater than 6 for one decade of the molar mass. Because calibration curves are usually not linear, this decade should lie nearly symmetrically around the peak maxima of the samples in question. The required value of 6 is easy to fulfill, as results of 10 or more are usual with modern columns. If so-named linear or mixed... 

Gel permeation chromatography was performed in tetrahydrofuran using a Waters pump system and a Model 410 differential refractive index detector for the eluant. Five Ultrastyragel columns with nominal porosities ranging from 500 to 105 angstroms were used for all the samples and the polystyrene standards. 

Figure 2 Chromatogram from conventional SEC column compared to high-speed SEC column tested on an identical instrument with polystyrene standards in tetrahydrofuran (THF). (See Color Plate Section at the end of this book.)...

Fig. 14 a, b. Effect of gradient steepness on the very fast separation of polystyrene standards in a molded monolithic poly(styrene-co-divinylbenzene) column (Reprinted with permission from [121]. Copyright 1996 Elsevier). Conditions column, 50 mm x8 mm i.d., mobile phase, linear gradient from 100% methanol to 100% tetrahydrofuran within a 1 min b 12 s, flow rate, 20 ml/min, peaks represent polystyrene standards with molecular weights of 9200,34,000 and 980,000 (order of elution), 3 mg/ml of each standard in tetrahydrofuran, injection volume 20 pi, UV detection, 254 nm... 

Six commercial narrow UWD polystyrene standards ( Applied Research Laboratories Limited, England ) and five broad MWD 2-polybuta-diene fractions were used to calibrate an ARL 950 GPG instrument with silica bead packed columns. The ARL polystyrene standards were also used to calibrate a number of homeMnade SEC column units packed with silica beads or styrene-divinylbenzena copolymer beads, Hie average molecular weights of these samples are listed in Table I. Tetrahydrofuran or toluene was used as eluents for these columns. 

Gas Permeation Chromatography—Viscometry of Polystyrene Standards in Tetrahydrofuran... 

Two series of narrow MWD polystyrene standards were used to calibrate a SN-01A GPC equipment, one of which (TSK) was supplied by Toyo Soda Co. and the other (NFS) was prepared and characterized in this laboratory. The column (3x1 M) were packed with NDG porous silica beads. Tetrahydrofurane was used as eluent. The elution volume was counted by a 2.60 ml. siphone tube. 

Gel Permeation Chromatography. Each ozonized lignin was analyzed by liquid chromatograph (ALC/GPC 201 with R-401 Differential Refractome-ter Water-Associates). Columns and solvent conditions were as follows p-Styragel 1,000, 500, 500,100A in series and tetrahydrofuran at 2.0 ml/min. Molecular weight was estimated by use of polystyrene standards. 

The GPC analysis was conducted using a seven column Styragel arrangement with tetrahydrofuran as the carrier solvent. Solution concentrations of 1/8% (w/v) were used. The flow rate was 1 ml min-1. The characteristics of this column arrangement are presented elsewhere (20,21). The Styragel columns were calibrated using eleven polystyrene standards. All of the polystyrenes prepared in this work were analyzed by gel permeation chromatography. Without exception, all samples were found to have values of Mz/Mw<1.07 and values of / . 05. None of... 

Method for Generating Molecular Weight and HDV Calibration Curves in TFE Using Polystyrene Standards in Tetrahydrofuran. The indirect procedure used for constructing HDV calibration curves in TFE at 50 °C using polystyrene standards in tetrahydrofuran at 25 °C described previously (1) deserves some clarification because of an error generated in the use of this method. The correct procedure is summarized below ... 

Fig. 3. Isocratic separation of oligomers from a polystyrene standard (M = 2100 g/mol) on a silica column (250 x 4 mm do = 6 nm dp = 5 pm). Injection m0 = 0.3 mg in 10 pi eluent n-pentane — tetrahydrofuran (87 13, v/v) flow rate 1 ml/inin UV detection at 254 nm. (From Ref.14) with permission)...

Fig. 4a. Adsorption HPLC of polystyrene standards. Column silica (250x2.6 mm d0 = 400 nm dP = 10 pm) gradient decalin/tetrahydrofuran flow rate 0.5 ml/min UV detection at 254 nm. (From Ref. U) with permission), b. SEC of polystyrene standards. Column silica (three columns in series, each 250 x 4 mm nominal pore size 100,500, and 1000A, respectively). In both chromatograms the figures at the peaks indicate the molar mass (kg/mol) of the respective polystyrene standard. (From Ref. li with permission)...

Molecular weights of the polystyrene were determined using a Polymer Laboratories gel permeation chromatograph (GPC) with tetrahydrofuran (THF) as the mobile phase the values reported are relative to narrow molecular-weight polystyrene standards. The polystyrene and polyethylene were separated by dissolving the blends in xylenes at 120 °C and precipitating the polyethylene in a 2 1 (vol/vol) mixture of acetone and cyclohexane. After filtration, polystyrene was isolated from the resulting solution by rotary evaporation. 

Figure 2.14 Molecular weight calibration curves for porous silica microsphere columns. Chromatography conditions column, 10 X 0.78 cm mobile phase, tetrahydrofuran, 22°C flow rate, 2.5 ml/min detection, UV absorbance at 254 nm sample, 25 pi solutions of polystyrene standards, (a) Four individual columns showing four different calibration ranges (b) four columns in series with two distinct pore sizes (60,60,750,750A), providing a single calibration curve with a broader molecular weight range than the individual columns. (Adapted from Ref. 54 with permission.)...

Gel Permeation Chromatography (GPC). GPC was used to determine molecular-size distributions of asphalts and their fractions. Chromatograms were obtained by means of a Waters Associates ALC/GPC 301 chromatograph equipped with 8.5 x 103-, 103-, 500-, and 70-A Styragel columns. The instrument was operated at ambient temperature. Tetrahydrofuran (THF) was used as the solvent. Concentration of the sample in tetrahydrofuran was less than 0.5 wt %. The flow rate was 1 mL/min. Monodispersed polystyrene standards provided by Waters Associates were used to calibrate the system. Thus, weight-average molecular weights (Mw) determined represent relative molecular size only. 

Gel permeation chromatographic (GPC) analysis of the molecular weight distribution of the polymers was performed with a Perkin-Elmer series 10 liquid chromatograph equipped with an LC-25 RI detector (25 °C), a 3600 data station, and a 660 printer. A Perkin-Elmer PL 10- xm particle mixed-pore-size cross-linked polystyrene gel column (32 cm by 7.7 mm) was used for the separation. The eluting solvent was reagent-grade tetrahydrofuran (THF) at a flow rate of 0.7 mL/min. The retention times were calibrated against known monodispersed polystyrene standards with MpS of 194,000, 87,000, or 10,200 and for which the ratio Mw/M is less than 1.09. 

Rg. They used an iterative approach to make this calculation and showed that good agreement with the expected values for polystyrene standards in tetrahydrofuran (THF) were obtained for from 1.06 X 10 to 2.3 X 10 Da. They also obtained values for Rg in good agreement with literature values over the range of 12 to 72 nm. 

A Waters GPC 150 CV, equipped with the DRI prototype 4 and a single capillary viscometer, was used for this study. A low-angle laser lightscattering (LALLS) detector (Chromatix CMX 100) was inserted between the column set and the GPC 150 CV detectors. Tetrahydrofuran (THF) was used at 40 °C and at a flow rate of 1 mL/mn. THF was filtered on a Millipore membrane-type FH and stabilized by lonol at a concentration of 0.04%. The columns used were a set of Waters Ultrastyragel (103—106 A). The narrow standards used for calibration were a set of polystyrene standards... 

The application of universal calibration requires a primary column calibration with elution of narrow MWD standards. For SEC in tetrahydrofuran, polystyrene (PS) standards are generally used. Intrinsic viscosities of the standards are either known or calculated from the proper Mark-Houwink equation, so that the plot of log[7j]psMps values versus retention vol-... 

In a similar manner, 1,1,4-cyclohexanetrimethanol (3.524 g, 20 mmol) was allowed to react with triethyl orthopropionate (3.634 g, 20 mmol). This reaction produced a polymer which remained in the cyclohexane solution. Precipitation into methanol yielded a polymer having a MW of 51 000 (GPC using polystyrene standards) and a Tg of 67.8 °C. The polymer was soluble in organic solvents with low or medium polarities such as methylene chloride, chloroform, ether, tetrahydrofuran and ethyl acetate. 

A Nicolet Magna 550 Fourier Transform Infrared Spectrometer (FTIR) and a Bruker MW 250 MHz proton NMR were used to verify the chemical structure of all monomers and polymers. Optical activity of the compounds was measured at 25 on a Perkin-Elmer Polarimeter in chloroform. A Waters Gel Permeation Chromatograph with 440 UV absorption detector and R401 differential refructometer was used to determine the molecular weights of the polymers tetrahydrofuran was used as the mobile phase at 1.0 mL/min, and the Waters polystyrene gel columns were calibrated with monodisperse polystyrene standards. Polarizing optical microscopy was used to identify liquid crystalline phases using a Leitz optical microscope with a CCD camera attachment... 

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