<=?6-o3 # =?Characterization of Degradation Products from Antioxidants in Polyolefins

utilizinga Photo Diode Array Detector coupled with a Particle Beam LC/MS.

Matthew J. Dilts,Waters Chromatography,MilfordMA, 01757

INTRODUCTION

The additivepackage for polyolefinscan be quite complex,including

componentssuchas antioxidants,antistats,slips,and pigments. It is important

forthe polymermanufacturerto be able to determinethe exactamountof each

additivecomponentpresent inthe polymerfor processingand longevityof the

processedmaterial. 1 The pharmaceuticaland food industriesare also under

mandate fromthe Food and Drug Administrationto analyze any packaging

materialwhichcomes intocontactwithany productssoldfor human

consumption.Specificallytheyare lookingfor materialswhich may have

undergone UV or thermaldegradationand leachedout of the polymeric

material.

,U_S_SLOUIn the past, analysisof additivepackageshas been performed usingsingle

wavelengthanalysisandwide bore chromatography.The additive packages

used in polyolefinmanufacturingare typicallynot complexthussingle

wavelengthchromatographicsystemsare sufficientfor the analysisof a clean

additivesample. However, ifdegradationof the additives has occurred,the

sampleextract may be quitecomplex,containingseveral degradationproducts

for each additivepresent inthe polyolefin. Thus itmay be very difficultto

separate the additivesfrom the degradationproductsin a sample usingwide

bore chromatography.

A betterway to analyze thesesampleswouldbe to use narrow bore

chromatographyin combinationwith a photodiodearray detectorand a

787

ThermaBeam mass detector. Narrow bore columns provide the

chromatographer with a better means of separating coelluting peaks. Photo

diode array detection can provide minimal structural information about a

compound but is also suited for determining if a peak is homogenous or not.

The ThermaBeam particle beam interface coupled with a mass detector is suited

for structural determination since it is able to generate electron impact spectra.

Electron impact spectra are interpretable spectra which can be compared to

large commercially available spectral data bases. The combination of these two

detector technologies provides the analyst with the ability to identify the source

of polymer degradation products.

EXPERIMENTAL

This study will look at the resulting degradation products of various antioxidants

exposed to high temperatures and UV light. Specifically, we will look at the

degradation products of Isonox 129, Irganox 1010, Irganox 1076, and Irgafos

168. The samples will be separated by reverse phase chromatography on a

Waters TM Nova-Pak C18 column (2mm X 150mm) using the following liquid

chromatographic conditions:

Gradient conditions.

Solvent A: Water

Solvent B: Acetonitrile

Gradient: 60% to 100% B in 6 minutes hold for 20 minutes

Flow rate: 0.35 ml/min

Column temperature: 50C

788

The mass detectionsystemused is a WatersTM Integritysystemwhich consists

of the followingequipment:

WatersTM Integrity.

ThermaBeamTM massdetector

:ed WatersTM 996 PhotoDiodeArrayDetector

616 SolventDeliverySystem

717 plusAutosampler

_o MillenniumTM 2010 data system

1. Nielson, Richard C., Journalof LiquidChromatography,Vol. 14, #3, 3-91

J

789

let ,__, .... , ..... _ ........... ,,.._.._ .... • .,

,Polyolefincontainersare used for the•packaging of many food and drugproducts sold for human consumption.

Pharmaceutical and Food industries

Any compounds which may have leachedout

Complex: Antioxidants(hinderedphenols), antistats, slips, and pigments

_O

Single wavelength analysis

Coelution

•" : A:Better Way!

,-Narrow bore chromatography

_-PDA detection

,- Mass Detection

b_ective-q............_._j ,.. _

,_Chromatographically separate apolyolefin additivespackage by reversephase HPLC.

_-Showthe utilityof couplinga massdetector with a photodiode arraydetector.

,-Generate Electron Impact mass spectrafor polyolefin additives using particle

s

beam LC/MS.

What is Particle Beam? '

LC/MS interfacetechnique_,Two .maincomponents

• Aerosol generation: Nebulization

• Enrichment: Momentum SeparationPatented technique - ThermaBeam• Electron Impact (El) spectra• Structural information

• Molecular weight information

_'L. -library searchablespectra

_.MomentumSeparator

",4

P-Nebulizer

,. Integrity ---AutomatedInjection SystemControl MassDetection

and Data

2010

GradientHPLC

n===== PDA UV Detection

AutomatedMassDetectorTuning

Separation '

,-Waters NovaPak C18 column2mm x 150mm

Chromatography_ • Solvent .A:Water

• Solvent B: Acetonitrile

• 60%-100% B in 6 minutes hold for 20 minutes ata flow rate of 0.35ml/min

• Column heated to 50°C

File __Edit View Plot Options _indows_Applications Help

PDAMaxPIot of

sixAntioxidants

PDA Processin_ Method Additives MaxPIot PDA

SpectrumIndex Plot

sixAntioxidants

_.File __Edit._o

PDAMatch Results PurityResults for

BHTstandard

MaxImpurity

plot for BHT

3D CubeofAntioxidantstandard

SpectrumIndex Plot

for BHT andIrganox

1076

S Jeclrum Index - ADDITIVE S _

_Edit _Plot Help , _ ...

SpectrumIndex Plot of

Additivesample

SpectrumReview of BHT

degradationproduct

File Edit Plot _Derived Help ...New Library...Open Library...Delete Library...

Close LibraryAdd to Library ...._emovc from Library

I_atch against IL_ihra,_y Rnectral_Br uv IB II

_ Match Parameters... SearchLibraries

Triple PlotSearch result

for BHTdegradation

product

File Edit Options Help ',.. ....°_,

_ Purity ResultsM_.s.o=,a,M=_._.n_ _.... for Library

.', Search of BHTdegradation

product

_.File Edit Options Help

- Purity, ResultsRetention Time: 13.882 Minutes Peak: 5 of 6

Peak Limits: 13.61 5 to 14.448 Baseline-to-Baseline

PurityAngle: 0.47 Purity Threshold: 1.34

PDAMatch Results

Match ThresholdMatchSpectrUmNameLibrarYNameIdeal VVvlnRMs Peak Purity0.000 1.438 ano×1076 Additives PDA Yes 0.0000 Graphical

display

File Edit Plot '_Help

SpectrumIndex plot for

unknowndegradation

product

., Conclusions

_-Ableto chromatographicaly separateadditives standards ,and samples by reversephase HPLC

oo

_-Demonstrated the utility of coupling a PDAdetector with an mass detector

Able to genera!e library searchable I .spectra for add_t_ves_and their degradationproducts