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Summary

The molecular weight distribution of

is obtained with Size Exclusion Chromatography (SEC). 

The results are shown in the table. 

SEC Summary information 

Weight Average Molecular Weight = 

Number Average Molecular Weight = 

Z Average Molecular Weight = 

Polydispersity index = 

Table 1: MWD of CAS 

The oligomer fraction > 452 g/mol and < 500 g/mol = and the 

oligomer fraction > 452 g/mol and < 1000 g/mol = 
Introduction 

This method is applicable for the determination of molecular weight distribution of 

Joncryl resins or other resins which are soluble in tetrahydrofuran (THF). 

Size exclusion chromatography (SEC) is a chromatographic method in which 

particles are separated based on their molecular weight (size) or even better their 

hydrodynamic volume. 

Figure 1: Illustration of the SEC theory.

The samples are dissolved in THF and the sample solution is injected into a 

liquid chromatography (HPLC). Separation is made on a SEC column set and is 

monitored with a refractive index detector. The molecular weight distributions of 

the samples are determined with a polystyrene calibration curve. The calibration 

curve is based on standards with known molecular weight. 

Experimental work

Reagents 

Tetrahydrofuran (stabilised with 0.025% BHT, dry solvent): HPLC grade, 

available from Fisher Chemicals (productnr. T/0701/17) or equivalent. 

PS-1 EasiCal standards: Mw 580 -7500000 Da, available from Polymer Labs, 

Varian Inc. (part nr. 2010-0505). 

Materials

1.8 ml GC or HPLC vials and caps. 

Capper. 

4 decimals balance. 

3 ml disposable polyethylene pipets. 

10-100 μl variable eppendorf pipet and tips. 

100-1000 μl variable eppendorf pipet and tips. 

1000-10000 μl variable eppendorf pipet and tips. 
Instrumental operating conditions 

Instrument: 

WATERS 2690 separations module with an on-line degasser 

Detector: 

WATERS 2414 Refractive index detector, temperature detector = 40 °C 

SEC column set:

1 × PL gel guard 10 μm MIXED B (1110-1220, 50*7.5 mm) + 2 × PL gel 10 μm 

MIXED B (1110-6100, 300*7.5 mm) in serial.

Mobile phase:

100% THF 

Column temperature:

40 °C 

Injection volume:

50 μl 

Elution time:

26 min 

Flow rate:

1 ml/min 

EZChrom Elite of Scientific Software, Inc. was used as a data acquisition system. 

 

Sample preparation

SEC calibration

For the SEC calibration 0.1 m/v % solution of the polystyrene standards were 

prepared in the mobile phase (THF). The standards were allowed to dissolve by 

gently stirring or shaking of the solution and with these standards a first order 

calibration curve was established. 

 

Sample measurement

The samples were also dissolved in the mobile phase. 100 μl of a formulation 

was dissolved in 1.8 ml to get 0.025 m/v % solution. The polymers were allowed 

to disperse by gently stirring or shaking of the solution. 

Results and conclusion 

The system was calibrated with 10 narrow standards of polystyrene, so all 

molecular weight distributions are quoted relative to polystyrene. 

Based on the retention times and the nominal average molecular weights (Mw) 

supplied by Polymer Laboratories a 1e first order calibration curve and an 

equation were generated with EZChrom Elite. Figure 1 shows the calibration 

curve and the raw data of the standards. 
 Figure 1: 1e

 first order calibration curve of polystyrene standards.

The molecular weight distribution of was determined with a 1e

order calibration curve. 

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Figure 2: SEC chromatogram of 

Minutes

0 2 4 6 8 10 12 14 16 18 20 22 24 26

mVolts

-100

0

100

200

300

mVolts

-100

0

100

200

300

The results are shown in table 2. 
SEC Summary information 

Processing Start Time(min) =

Processing Stop Time(min) =

Reference peak Offset Time(min) =

Number of Slices =

Weight Average Molecular Weight =

Number Average Molecular Weight =

Z Average Molecular Weight =

Z+1 Average Molecular Weight =

Polydispersity index =

Peak Molecular Weight =

Z Average / Weight Average =

Z+1 Average / Weight Average =

Table 2: MWD of CAS 

The oligomer fraction > 452 g/mol and < 500 g/mol = and the 

oligomer fraction > 452 g/mol and < 1000 g/mol = 
APPENDIX 1: Slice report CAS