hyphenating convergence chromatography with uv and ms detection for compositional, impurity and...

©2014 Waters Corporation 1

Hyphenating Convergence Chromatography with UV and MS Detection for Compositional, Impurity and Degradation Analysis of High

Performance Electronic Materials

Jane Cooper Tue 20th May, 2014

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Introduction

Background information about Liquid Crystals

Current Analytical Methods

Convergence Chromatography (UPC2)

Examples:

o Impurity and degradation analysis o Compositional analysis

Interfacing UPC2 with MS detection


Background - Liquid Crystals

Properties: o Some properties of liquids:

• Flow, pour like liquids and take the shape of containers o Some optical properties of solids:

• Birefringence • Optical activity

o React predictably to an electric current, enabling the control of light passage

Liquid crystal intermediates: o Building block compounds used to prepare liquid crystals

• Used in mixtures (10 to 20 singles used in a typical mixture)



A twisted nematic cell In the “off” state, in the absence of an electric field, the assembly is transparent to light. In the “on” state, an applied field destroys the twist of the nematic, rendering the assembly opaque. Credit: Encyclopedia Britannica. Inc.



Uses: o Electronic displays:

• Watches, calculators, notebooks, mobile phones, projectors, desktops monitors / TVs, viewfinders on cameras / camcorders…..



Existing methods used to characterize liquid crystal intermediate compounds:

• Differential Scanning Calorimetry • Fourier Transform Infrared • Raman Spectroscopy • Ultraviolet Absorption Spectrophotometry • Optical Microscopy

– For the impurity profiling and compositional analysis typically a

chromatographic technique would be used: • HPLC with UV detection • HPLC with MS detection • GC with MS detection



– These techniques have some limitations:

• The compounds might not be thermally stable and / or volatile

• Limited sample availability

• The sample solubility might be incompatible with the solvent required for the technique • Therefore requiring additional sample preparation stages

• Long analysis times with insufficient selectivity and sensitivity



Convergence Chromatography (CC) is a normal phase separation technique – Uses carbon dioxide as the primary

mobile phase – Choice of adding an co-solvent such

as methanol or acetonitrile

The Waters UltraPerformance Convergence Chromatography (UPC2) builds upon the potential of CC while using proven and robust Waters UPLC technology.

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Many liquid crystal intermediate compounds:

– Are not very stable at high temperatures – Have low volatility – Have similar UV spectra

Therefore, utilizing the separation powers of UPC2 with CO2 as the mobile phase is an ideal alternative to both HPLC and GC analysis


UPC2 Examples

Impurity Profiling Analysis

– Impurities can be present due to many factors, including contamination, as by-products, or as degradation products

– Purity is critical to ensure the optimum quality, performance and lifetime of the electronic display device

Compositional Analysis

– Composition is critical to ensure physical properties and

characteristic of the liquid crystal. o Even just small changes can have pronounced effects


Liquid Crystal Intermediate Compounds

4-(Octyloxy)benzoic acid

4-Butoxybenzoic acid

4-Cyanobenzoic acid

4,4′-Azoxyanisole-d14

(internal standard)

4-Butylbenzoic acid

4-Octylbenzoic acid


Methods

UPC2 conditions CCM back pressure: 2000 psi Sample temp.: 20 oC Column temp.: 50 oC Injection volume: 1 µL Column: ACQUITY UPC2 CSH Fluoro-phenyl, 3.0 mm x 100 mm, 1.7 µm Mobile phase A: CO2 Mobile phase B: Methanol (2% Formic Acid + 15 mM ammonium acetate) PDA conditions UV system: ACQUITY UPC2 PDA Detector Range : 210 to 450 nm Resolution: 1.2 nm Sampling rate: 20 pts/sec Filter time constant: Slow (0.2 sec)



Chemical Substance CAS

Number

Retention time

(minutes)

UV optimum absorbance

(nm)

4,4′-Azoxyanisole-d14 39750-11-3 0.69 346

4-Butylbenzoic acid 20651-71-2 1.39 235

4-Octylbenzoic acid 3575-31-3 1.62 235

4-Cyanobenzoic acid 3575-31-3 1.75 252

4-Butoxybenzoic acid 1498-96-0 1.90 252

4-(Octyloxy)benzoic acid 2493-84-7 2.09 235


Calibration Curve


UV Chromatograms and UV Spectra


252 nm

235 nm

346 nm

4-Cyanobenzoic acid (0.001 mg/mL)

4-Butylbenzoic acid (1 mg/mL)

4,4′-Azoxyanisole-d14 (internal standard)

4-(Octyloxy) benzoic acid (0.001 mg/mL)

4-Butoxybenzoic acid (0.001 mg/mL)

Impurity Profiling


Liquid Crystal Intermediate Compounds Merck E7 (liquid crystal intermediate compounds)

4-cyano-4'-n-pentyl-biphenyl

4-cyano-4'-n-heptyl-biphenyl

C18H19N C20H23N

4-cyano-4'-n-oxyoctyl-biphenyl

4-cyano-4''-n-pentyl-p-terphenyl C21H25NO

C24H23N


Methods

UPC2 conditions CCM back pressure: 1800 psi Sample temp.: 20 oC Column temp.: 60 oC Injection volume: 1 µL Column: ACQUITY UPC2 BEH 2-EP, 3.0 mm x 100 mm, 1.7 µm Mobile phase A: CO2 Mobile phase B: Acetonitrile PDA conditions UV system: ACQUITY UPC2 PDA Detector Range : 190 to 450 nm Resolution: 1.2 nm Sampling rate: 20 pts/sec Filter time constant: Slow (0.2 sec)



Chemical Substance CAS

Number Retention time

(minutes) UV optimum

absorbance (nm)

4-cyano-4'-n-puntyl-biphenyl 5CB 40817-08-1 0.889 269

4-cyano-4'-n-heptyl-biphenyl 7CB 41122-71-8 1.012 269

4-cyano-4'-n-oxyoctyl-biphenyl 8OCB 52364-73-5 1.469 287

4-cyano-4''-n-pentyl-p-terphenyl 5CT 54211-46-0 1.742 292


Calibration Curve


UV Chromatograms and UV Spectra

4-cyano-4'-n-heptyl-biphenyl

4-cyano-4'-n-oxyoctyl-biphenyl

4-cyano-4'-n-puntyl-biphenyl

4-cyano-4''-n-pentyl-p-terphenyl



blank

Correct ratio

Incorrect ratio

51%25% 16% 8%

40%25% 23% 12%

Chemical Substance Correct ratio Incorrect ratio

Prepared %

Calculated %

Prepared %

Calculated %

4-cyano-4'-n-puntyl-biphenyl 5CB 51.0 51.3 40.0 40.4

4-cyano-4'-n-heptyl-biphenyl 7CB 25.0 24.9 25.0 24.9

4-cyano-4'-n-oxyoctyl-biphenyl 8OCB 16.0 15.9 23.0 22.7

4-cyano-4''-n-pentyl-p-terphenyl 5CT 8.0 8.0 12.0 12.1



Correct ratioIncorrect ratio



MS splitter

From the Column manager or PDA

From the makeup pump

To the convergence Manager

To the MS

Waters ACQUITY UPC2 configured with PDA and MS detection (here illustrated with an SQD), including MS splitter and a makeup pump



Electrospray Ionization (ESI) – An electrically charged field is used to generate charged droplets,

then analyte ions are formed by evaporation prior to MS analysis – The addition of a protonation source such as formic acid to the

makeup solvent can be used to enhance ionization and increase sensitivity

Atmospheric Pressure Photo Ionization (APPI) – Ultraviolet light produced from a krypton lamp ionizes gas phase

analytes and dopants leading to gas-phase reactions – Therefore, the addition of a dopant such as toluene to the makeup

solvent can enable and enhance ionization

Atmospheric Pressure Chemical Ionization (APCI) – The solvent present, from both the co-solvent and the makeup

solvents, acts as chemical ionization reagent gas in order to ionize the sample



MS conditions

Mass Spectrometer Xevo TQD

Ionization mode APCI APPI ESI

Corona 3.0 µA N/A N/A

Capillary N/A N/A 5.00 kV

APCI probe temp. 300 oC 300 oC N/A

Source temp. 150 oC

Repeller N/A 0.50 kV N/A

Desolvation gas 800 oC 600 oC 600 oC

Cone gas 0 L/hr

Acquisition Multiple Reaction Monitoring (MRM)

MS splitter conditions

Makeup pump Waters 515

Solvent Methanol Methanol + 10% toluene Methanol + 1% formic acid

Flow 0.4 mL/min



Tuning: – 2 ppm standards in methanol – The compounds were tuned in APCI – MRM, transitions, cone and collision energy values optimized using Xevo TQD fluidics

only:

Compound CAS Mol formula Molecular weight

APCI (+/-)

Cone Voltage (V)

MRM Transition

(m/z)

Collision energy

4-(Octyloxy)benzoic acid 2493-84-7 C15H22O3 250.33 + 40 251.2 > 121.0* 20

251.2 > 139.0 20

4,4′-Azoxyanisole-d14 39750-11-3 C14H13DN2O3 272.36 + 30 273.2 > 114.1* 25

273.2 > 142.1 20

4-Butoxybenzoic acid 1498-96-0 C11H14O3 194.23 + 30 195.0 > 95.0* 20

195.0 > 121.0 20

4-Butylbenzoic acid 20651-71-2 C11H14O2 178.23 + 30 179.1 > 123.0 10

179.1 > 161.0* 15

4-Cyanobenzoic acid 619-65-8 C8H5NO2 147.13 - 25 146 > 102.0* 15

4-Octylbenzoic acid 3575-31-3 C15H22O2 234.33 + 35 235.0 > 123.0* 15

235.0 > 217.0 20

*refers to the quantification transition



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4-Octylbenzoic acid

4-(Octyloxy)benzoic acid

4-Butoxybenzoic acid

4-Butylbenzoic acid

4-Cyanobenzoic acid

4,4′-Azoxyanisole-d14


Conclusion

Separation by UPC2 is an ideal alternative to both HPLC and GC analysis

UPC2 with PDA detection offers a cost effective and efficient impurity profiling and compositional analysis

UPC2 with MS detection: – greater selectivity and specificity – orthogonal technique

Many business and analytical benefits, when compared

HPLC for the analysis of liquid crystal intermediate compounds


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hyphenating convergence chromatography with uv and ms detection for compositional, impurity and...

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