Full Characterization of Polymers Using the ACQUITY Advanced Polymer Chromatography (APC) System with Multi-Detection

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[ APPLICATION NOTE ]

WATERS SOLUTIONS
ACQUITY Advanced Polymer 
Chromatography™ (APC) System

ACQUITY APC XT Columns

KEYWORDS
Size Exclusion Chromatography, SEC, Ultra 
High-Performance Liquid Chromatography, 
UHPLC, GPC, polystyrene, PS1478  
and PS706a, polyvinylchloride,  
PVC, polycarbonate

APPLICATION BENEFITS
The ACQUITY™ APC™ System  employs high 
efficiency separation columns and a low 
dispersion flow path, resulting in:

■

High resolution analysis

■

Shorter analysis times

■

Reduced solvent consumption

■

Reduced sample concentration

Full Characterization of Polymers Using the ACQUITY Advanced Polymer 

Chromatography (APC) System with Multi-Detection
Larry Meeker1 and John Stenson2 
1 

Waters Corporation, Houston, TX, USA; 2 Malvern Panalytical, Houston, TX, USA

INTRODUCTION
In recent years, new developments in the area of Size Exclusion 
Chromatography (SEC) have resulted in the introduction of Ultra High-
Performance Liquid Chromatography (UHPLC) for polymer applications. 
Waters™ ACQUITY Advanced Polymer Chromatography (APC) is a 
breakthrough technology that is able to provide SEC analyses of polymeric 
materials with enhanced resolution and speed than conventional SEC. 
The APC System employs Refractive Index (RI) and Ultraviolet PDA (UV) 
to generate relative molecular weight information versus conventional 
calibration techniques that use elution volume/retention times. 

Similar improvements have been made to advanced GPC/SEC technologies 
such as viscometers and light scattering detectors to make them  
compatible with APC. Malvern Panalytical recently introduced a version  
of the OMNISEC REVEAL advanced detector unit that through a collaboration 
with Waters has been optimized for integrated use under APC conditions.

In this application note, the analyses of several polymers by ACQUITY APC 
combined with the OMNISEC REVEAL are presented and discussed.

Figure 1. ACQUITY APC System with OMNISEC REVEAL.

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Full Characterization of Polymers Using the ACQUITY Advanced Polymer Chromatography (APC) System with Multi-Detection

[ APPLICATION NOTE ]

[ APPLICATION NOT

EXPERIMENTAL

Sample description 
Two NIST polystyrene (PS) standards, PS1478 
and PS706a, a broad polyvinylchloride (PVC) 
and a broad polycarbonate (PC) 

LC conditions
LC system:  

ACQUITY APC

Detection: 

OMNISEC REVEAL with 
RI, LS (RALS 90° angle, 
LALS 7° angle), and  
IV detectors 

Vials:  

Waters vials with  
pre-slit septa

Column  

ACQUITY APC XT,  
150 mm, 900 Å, 450 Å, 
and 200 Å, in series

Column temp.:  

35 °C

Sample temp.:  

35 °C

Injection volume: 

20 µL 

Flow rate: 

1.0 mL/min 

Mobile phase:  

THF (unstabilized) 

Data management
ACQUITY APC operation: Standalone 
ACQUITY Console Software

OMNISEC operation, data collection,  
and processing: Malvern Panalytical  
OMNISEC software

RESULTS AND DISCUSSION

NIST POLYSTYRENE STANDARDS
A chromatogram for the NIST PS1478 polystyrene narrow molecular weight 
standard is shown in Figure 2. Also shown in Figure 2 is the Log molecular 
weight, Log intrinsic viscosity (IV), and Log hydrodynamic radius (Rh). 
Figure 3 shows the chromatogram for the NIST PS706a polystyrene broad 
molecular weight standard. Also shown in Figure 3 is the Log Mw, Log IV, 
and Log Rh. 

Both chromatograms demonstrated excellent detector response with  
low sample loadings. 

Figure 2. RI, RALS, and DP chromatograms obtained from a PS1478 NIST standard.  

10 µL injection volume, 2.5 mg/mL concentration. Log Mw, IV, and Rh are also shown.

Figure 3. RI, RALS, LALS, and DP chromatograms obtained for a PS706a NIST standard.  

5 µL injection volume, 2 mg/mL concentration. Log Mw, IV, and Rh are also shown.

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Full Characterization of Polymers Using the ACQUITY Advanced Polymer Chromatography (APC) System with Multi-Detection

[ APPLICATION NOTE ]

Table 1 shows the quantitative results obtained 
from the OMNISEC-REVEAL. The absolute 
molecular weights were calculated directly 
from Right Angle Light Scattering (RALS) and 
Low Angle Light Scattering (LALS). In addition, 
the viscometer provides the ability to calculate 
the size and structural information about the 
polymers. The values of molecular weight, 
dispersity (Mw/Mn), intrinsic viscosity (IV), 
hydrodynamic radius (Rh), and the  
Mark-Houwink plot, and log K parameters were 
all consistent with the values expected. The 
calculated values of PS706a and PS1478 matched 
the NIST certified Mw values of 285±0.23K g/mol 
and 37.4±0.26K g/mol respectively, illustrating 
excellent precision and accuracy.

Table 1. Molecular weight, size, and structure results for PS1478 and PS706a.

Parameters

Samples

PS1478

PS706a

Retention volume (mL)

4.47

3.28

Mn (g/mol)

35,790

11,600

Mw (g/mol)

37,360

286,700

Mz (g/mol)

39,120

479,300

Mw/Mn

1.044

2.57

IVw (dL/g)

0.2322

0.9394

Rhw (nm)

5.144

15.34

Rgw (nm)

N/A

15.42

M-H a

0.7239

0.6534

M-H log K (dL/g)

-3.943

-3.534

POLYCARBONATE AND POLYVINYLCHLORIDE
Samples of polycarbonate (PC) and polyvinylchloride (PVC) were dissolved in the mobile phase and injected into the  
ACQUITY APC-OMNISEC REVEAL system. Figure 4 shows the chromatogram obtained for PC, and Figure 5 that for PVC.  
As with the NIST samples, both chromatograms show excellent detector response with low sample loadings.

Figure 4. Representative 

RI, RALS, LALS, and DP 

chromatograms with molecular 

weight, IV, and Rh distributions 

of polycarbonate (PC).  

10-µL injection volume,  

3 mg/mL concentration.  

Log Mw, IV, and Rh are  

also shown.

Figure 5. Representative 

RI, RALS, LALS, and DP 

chromatograms with 

molecular weight, IV, 

and Rh distributions of 

polyvinylchloride (PVC).  

10-µL injection volume,  

3 mg/mL concentration.  

Log Mw, IV, and Rh are  

also shown. 

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Full Characterization of Polymers Using the ACQUITY Advanced Polymer Chromatography (APC) System with Multi-Detection

[ APPLICATION NOTE ]

Table 2 shows the results obtained for PC and 
PVC by the ACQUITY APC-OMNISEC REVEAL 
system. The quantitative data obtained align  
with the expected results obtained previously 
using traditional GPC.

An overlay of the Mw distributions for duplicate 
injections of PC, PVC, and PS706a is shown in 
Figure 6. Figure 6 also demonstrates that the 
three samples (PC, PVC, and PS) have very 
different molecular weight distribution plots,  
with the PS sample shifted toward the high  
Mw region and PC toward the low Mw region.

The results in Table 1 and 2 show the average 
values for IV and Rh for the different polymers. 
These values can be used to make broad 
structural comparisons between samples, but 
to get a complete picture of the structure it is 
necessary to use a Mark-Houwink plot to look at 
the IV distribution across the entire Mw range. 

The Mark-Houwink plot in Figure 7 shows 
the structural comparison between the three 
different samples, PC, PVC, and PS706a. This 
plot shows the Log Mw plotted against the Log 
IV and allows structural differences between the 
samples to be clearly identified. PS is lowest on 
the plot indicating it has a lower IV than PC and 
PVC at comparable Mws. A lower IV is indicative 
of a higher molecular density and suggests  
a more compact configuration. PC has the  
highest IV value indicating it has the most  
open configuration. 

PVC has a density falling between PC and PS. 
In addition to this the IV of PVC deviates from a 
linear behavior, with decreasing IV values in the 
high Mw region. This indicates the presence of 
branching at higher molecular weights. It would 
have not been possible to obtain this insight  
into the polymer’s architecture without the  
use of a viscometer.

Parameters

Samples

PC

PVC

Retention Volume (mL)

4.34

3.87

Mn (g/mol)

12,220

39,750

Mw (g/mol)

23,060

84,460

Mz (g/mol)

33,650

268,600

Mw/Mn

1.886

2.124

IVw (dL/g)

0.4545

0.7351

Rhw (nm)

5.272

9.283

Rgw (nm)

N/C

N/C

M-H a

0.667

0.7063

M-H log K (dL/g)

-3.323

-3.566

Table 2. Molecular weight, size, and structure results for PC and PVC samples. 

Figure 6. Overlay of duplicate molecular weight distributions of PC, PVC, and PS.

Figure 7. Mark-Houwink plots of PC, PVC, and PS overlaid and compared to show  

structural differences. 

Molecular weight (Da)

PC 

PVC 

PS 

Region of 

branching in 

PVC 

Increasing molecular density 

Molecular weight (Da)

[ APPLICATION NOTE ]

Waters Corporation 
34 Maple Street 
Milford, MA 01757 U.S.A. 
T: 1 508 478 2000 
F: 1 508 872 1990 
www.waters.com

TA Instruments 
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New Castle, DE 19720 U.S.A. 
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F: 1 302 427 4041 
www.tainstruments.com

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trademarks of Waters Corporation. All other trademarks are the property of their respective owners.

©2020 Waters Corporation. Produced in the U.S.A.  February 2020  720006483EN  AG-PDF

CONCLUSIONS
The combination of the ACQUITY APC System with the OMNISEC REVEAL 
multi-detector system provides high quality, high-resolution and rapid 
sample analysis. The presence of the highly sensitive LS and RI detectors 
and the viscometer in the OMNISEC REVEAL system allowed for the 
calculation of absolute molecular weight, hydrodynamic radius, and 
structure of the materials. Two NIST polystyrene standards were correctly 
characterized using the system as well as PC and PVC samples. A structural 
comparison was performed using the Mark-Houwink plot with differences 
between samples observed and regions of branching within PVC identified. 

A comparison of the polymer characteristics was performed which would 
not have been possible using only a conventional calibration system. 
Accurate molecular weights and structural information can only be attained 
using a multi-detection platform, such as ACQUITY APC and OMNISEC 
REVEAL. The unique combination of ACQUITY APC separations with 
Malvern Panalytical’s advanced detectors offers greater resolving power 
with full sample characterization. 

Acknowledgements
The authors gratefully acknowledge Malvern Panalytical for providing  
the data presented in this application note.