Structural Confirmation of Polymeric Material Using MS/MS and Fragmentation Mechanisms

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Structural Cofirmatio of Polymeric Material Usig MS/MS ad Fragmetatio Mechaisms Kirste Crave, 1 Michael McCullagh, 1 Pascal Gerbaux, 2 ad Julie De Witer 2 1 Waters Corporatio, Machester, UK 2

1 Structural Cofirmatio of Polymeric Material Usig MS/MS ad Fragmetatio Mechaisms Kirste Crave, 1 Michael McCullagh, 1 Pascal Gerbaux, 2 ad Julie De Witer 2 1 Waters Corporatio, Machester, UK 2 Uiversity of Mos, Belgium A P P L I C AT IN B E N E F I T S Rapid data collectio Exact mass elemetal compositio Polymeric architecture cofirmatio INT R DU C T IN Polymeric materials are abudat i moder society coverig a broad rage of applicatios i idustries such as automobiles, textiles, packagig, medical, ad pharmaceutical, to ame a few. This icreasig complexity i applicatios has drive the eed to produce highly complex polymeric materials. Full characterizatio of a sample has become a vital part of the developmet process. Mass spectrometry ca be used to aswer may questios regularly asked by polymer scietists, icludig idetifyig ed groups, back boe architecture, ad repeat uit chemistry. A sigle-stage mass spectrometry experimet ca provide iformatio about the molecular weight of polymers ad polymeric dispersity. Performig a dual-stage mass spectrometry experimet (MS/MS) while iducig fragmetatio provides a extra layer of iformatio regardig the architecture of the polymer ad more detail about the ed groups. 1 Cofirmig the architecture of a polymer is importat because it impacts its physical properties, such as desity, stregth, viscosity, ad glass trasitio temperature. The physical properties of a polymer directly affect its applicatios. Polylactides have recetly attracted icreased attetio from both academic ad idustrial researchers due to their bio-compatible ad bio-degradable ature. This applicatio ote uses polylactide to demostrate how MS/MS fragmetatio patters ca be used to help determie the backboe architecture of a polymer. WAT E R S S LU T INS Xevo G2-S Q-Tof MassLyx Software K E Y W R D S Polymer aalysis, fragmetatio mechaisms, cofirmatio of backboe structure, polylactide, PLA 1

E X P E R IM E N TA L Sample Descriptio The sample was first dissolved i acetoitrile before further dilutio ad the additio of lithium chloride to produce the followig: 90 ppm polylactide ad 10 ppm

2 E X P E R IM E N TA L Sample Descriptio The sample was first dissolved i acetoitrile before further dilutio ad the additio of lithium chloride to produce the followig: 90 ppm polylactide ad 10 ppm lithium chloride (i acetoitrile). R E SU LT S A N D D IS C U S S IN Figure 1 shows the structure of the polylactide repeat uit, which has a omial mass of 144 Da, ad the ed groups for this sample. The first step i this experimet was to collect a MS spectrum, allowig the most appropriate io to be selected for MS/MS aalysis. The precursor io selected was m/z 903. Both the MS ad MS/MS spectra are show i Figure 2. MS coditios Mass spectrometer: Ioizatio mode: Ifusio rate: Sca time: Capillary voltage: Sample coe: Extractio coe: Xevo G2-S Q-Tof ESI positive 10 µl/mi 1 s 3.0 kv 45 V 5.0 V Figure 1. Polylactide repeat uit ad ed groups. Source temp.: 120 C Desolvatio temp.: 200 C (a) (A) MS Spectrum Coe gas: Desolvatio gas: Nitroge, 20 L/h Nitroge, 800 L/h LockSpray coditios Compoud: Leucie ekephali Mass: m/z (b) (B) MS/MS Spectrum m/z Flow rate: Capillary voltage: Collisio eergy: 20 µl/mi 3 kv 6.0 V m/z Figure 2. (a) MS spectrum of lithiated polylactide, the io at m/z 903 has bee highlighted, (b) MS/MS spectrum showig the fragmet ios from the m/z 903 precursor io. Structural Cofirmatio of Polymeric Material Usig MS/MS ad Fragmetatio Mechaisms 2

3 Closer iterpretatio of the MS/MS spectrum shows three series of ios, each 72 mass uits apart. Figure 3 shows each series labeled with a circle, a square, or a triagle. Uderstadig the fragmetatio mechaisms that occur to create these ios is extremely importat as it allows the scietist to determie the polymer architecture. The exact mass data that is geerated ca help guide this process by providig possible elemetal compositios. Figure 3. MS/MS spectrum of lithiated polylactide. Three io series have bee idetified ad labeled with a circle, a square, or a triagle. Structural Cofirmatio of Polymeric Material Usig MS/MS ad Fragmetatio Mechaisms 3

4 Figure 4 proposes a fragmetatio mechaism resposible for the iitial 86-mass uit loss ad cosecutive 72-mass uit losses (labeled with a square). This patter is cosistet with the loss of the iitiatig ed group from a liear polylactide. This polymer was sythesized by rig opeig polymerizatio usig methaol as the iitiator. Figure 5 shows a very similar fragmetatio mechaism; however, this time the polymer is losig the termiatig ed group (io series labeled with a circle). Agai, this mechaism is cosistet with a liear polymer. This is cofirmed by a sigle 90-mass uit loss as a brached polymer would lose multiple 90-mass uits. Fially, Figure 6 proposes two fragmetatio mechaisms that are resposible for the series labeled with a triagle, which is caused by both ed groups beig lost. Series 3 C 3 C C 2 86 mass uit loss C 2 72 mass uit loss Figure 4. The fragmetatio mechaism resposible for the iitial 86-mass uit loss ad cosecutive 72-mass uit losses. Series 3 C C 2 3 C 90 mass uit loss C 2 3 C C 2 72 mass uit losses Figure 5. The fragmetatio mechaism resposible for the iitial 90-mass uit loss ad cosecutive 72-mass uit losses. Structural Cofirmatio of Polymeric Material Usig MS/MS ad Fragmetatio Mechaisms 4

5 Series 3 C 176 mass uit loss 3 C C 2 C 2 Figure 6. The two fragmetatio mechaisms resposible for a total of 176-mass uit loss. The fragmetatio patter that was observed is cosistet with that published i scietific literature. 2 Iterpretatio of the MS/MS results ad a uderstadig of fragmetatio pathways allow us to cofirm that the sample is a liear polylactide. Kowig the architecture of the polymer is of great value. It ca cofirm the target compoud has bee sythesized, thereby determiig if the product ca be used for the desired applicatio. Structural Cofirmatio of Polymeric Material Usig MS/MS ad Fragmetatio Mechaisms 5

6 C N C LUSINS The Xevo G2-S Q-Tof was successfully used to collect MS ad MS/MS data o a polylactide sample. This iformatio was used to propose the architecture of a polymeric material. A measuremet that is vital to the idustry to cofirm the target compoud has bee produced. Refereces 1. Wesdemiotis C, Solak N, Polce MJ, Dabey DE, Chaicharoe K, Katzemeyer B. Mass Spectrometry Reviews DI /mas De Witer J, Lemaur V, Marsal P, Coulembier, Coril J, Dubois P, Gerbaux P. J Am Soc Mass Spectrom. 2010; 21: This applicatio ote demostrates a approach that is appropriate for may polymer systems. Waters, Xevo, ad MassLyx are registered trademarks of Waters Corporatio. Q-Tof ad The Sciece of What s Possible are trademarks of Waters Corporatio. All other trademarks are the property of their respective owers Waters Corporatio. Produced i the U.S.A. February EN AG-PDF Waters Corporatio 34 Maple Street Milford, MA U.S.A. T: F:

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