Pyrolysis GC–MS Reveals Different Phthalate Isomers in Vinyl Polymers
The Application Notebook
CDS 6000 Series Pyroprobe coupled to a GC–MS is beneficial in phthalate analysis of plastics. This application uncovers intriguing information about phthalates used in vinyl products.
Because pure vinyl is a rigid material, flexible finished vinyl products contain a high amount of phthalate plasticizer. During analytical pyrolysis, these plasticizers are easily thermally desorbed, producing a large peak at the end of the pyrogram, which can be identified using a library search and their unique retention times.
These phthalate plasticizers may also produce unique decomposition products. Electrical tape has a peak for dioctyl phthalate (DOP), and among other things, a decomposition product of DOP, phthalic anhydride (Figure 1).
Figure 1: Electrical tape at 300 °C.
Unique decomposition products can help with phthalate identification. In the next example (Figure 2), a clear vinyl and a green vinyl each contain typical pyrolysis products of PVC, like the aromatics benzene, toluene, and indene. Each vinyl also has large plasticizer peak. Each peak has a similar retention time and similar mass spectra. With such similar mass spectra, a library search could easily mischaracterize them.
Figure 2: Green Vinyl (top), Clear Vinyl (bottom), 700 °C. Phthalate decomposition products circled.
However, each plasticizer has a unique thermal decomposition product, circled in the figure. An ortho-substituted phthalate in the clear vinyl generates phthalic anhydride, but the para-substituted phthalate in the green vinyl generates 2-ethyl hexyl benzoate, helping to simply distinguish between the two.
It is interesting to note that the green vinyl was taken from a child's toy, in which certain phthalate plasticizers are regulated, and there are no regulation requirements for para-substituted phthalates.
The data presented here show clear advantages to identifying phthalates in vinyl materials using pyrolysis GC–MS.
CDS Analytical LLC
465 Limestone Rd, Oxford, PA 19363
tel. (800) 541-6593
Website: www.cdsanalytical.com/pyrolyzer
The Next Frontier for Mass Spectrometry: Maximizing Ion Utilization
January 20th 2025In this podcast, Daniel DeBord, CTO of MOBILion Systems, describes a new high resolution mass spectrometry approach that promises to increase speed and sensitivity in omics applications. MOBILion recently introduced the PAMAF mode of operation, which stands for parallel accumulation with mobility aligned fragmentation. It substantially increases the fraction of ions used for mass spectrometry analysis by replacing the functionality of the quadrupole with high resolution ion mobility. Listen to learn more about this exciting new development.
Liquid Chromatography to Analyze Vitamin D Proteins in Psoriasis Patients
January 21st 2025Can a protein involved in delivering Vitamin D to target tissues have an altered serum profile in psoriasis patients with cardiovascular disease? Researchers used liquid chromatography (LC) to help find out.
The Complexity of Oligonucleotide Separations
January 9th 2025Peter Pellegrinelli, Applications Specialist at Advanced Materials Technology (AMT) explains the complexity of oligonucleotide separations due to the unique chemical properties of these molecules. Issues such as varying length, sequence complexity, and hydrophilic-hydrophobic characteristics make efficient separations difficult. Separation scientists are addressing these challenges by modifying mobile phase compositions, using varying ion-pairing reagents, and exploring alternative separation modes like HILIC and ion-exchange chromatography. Due to these complexities, AMT has introduced the HALO® OLIGO column, which offers high-resolution, fast separations through its innovative Fused-Core® technology and high pH stability. Alongside explaining the new column, Peter looks to the future of these separations and what is next to come.
A Guide To Finding the Ideal Syringe and Needle
January 20th 2025Hamilton has produced a series of reference guides to assist science professionals in finding the best-suited products and configurations for their applications. The Syringe and Needle Reference Guide provides detailed information on Hamilton Company’s full portfolio of syringes and needles. Everything from cleaning and preventative maintenance to individual part numbers are available for review. It also includes selection charts to help you choose between syringe terminations like cemented needles and luer tips.
