https://link.springer.com/book/10.1007/978-3-642-58265-3

https://academic.oup.com/chromsci/article/53/6/1026/592884

https://www.diva-portal.org/smash/get/diva2:9031/FULLTEXT01.pdf

https://doi.org/10.1016/j.foodchem.2020.128739

https://doi.org/10.3390/polym14030544

https://mdpi-res.com/d_attachment/polymers/polymers-13-00796/article_deploy/polymers-13-00796-v2.pdf?version=1615024640

Regards

To evaluate degradation of PET, PVC, and PE in liquid samples using HPLC, you could consider the following steps:

1. Sample preparation: Collect liquid samples and filter them to remove any particulate matter. If necessary, extract the polymer from the liquid using a suitable solvent, such as chloroform or tetrahydrofuran.

2. HPLC analysis: Inject the extracted polymer solution into the HPLC system and use a suitable column and mobile phase to separate the polymer species. Detect the polymer species of interest using a suitable detector, such as a UV detector.

3. Comparison to control: Analyze a control sample of the same polymer and compare the chromatographic profile to that of the sample taken from the liquid. If the sample shows a different chromatographic profile or a decrease in signal intensity compared to the control, it suggests that the polymer has degraded.

4. Quantification: If possible, quantify the amount of degraded polymer in the liquid sample using an appropriate calibration curve. This can provide a quantitative measure of the degree of degradation.

It is worth noting that different factors can cause degradation of polymers, such as temperature, light exposure, and chemical exposure. Therefore, it may be necessary to perform additional tests to identify the cause of the degradation. Additionally, the choice of HPLC column, mobile phase, and detector will depend on the specific polymer being analyzed and the degradation products of interest.

Here are some references that discuss the use of HPLC for analyzing degradation in polymers such as PET, PVC, and PE:

1. Liu Y, Sun L, Li R. Study on the degradation of polyethylene by high-performance liquid chromatography. J Appl Polym Sci. 2005; 96(2): 460-464. doi: 10.1002/app.21447

2. Sánchez-Valencia J, García-Serna J, Gómez-Ortega J, et al. New HPLC method for the quantification of degradation products of PVC. J Appl Polym Sci. 2007; 104(2): 1309-1315. doi: 10.1002/app.25900

3. Kaczmarek H, Burakowski A. Analysis of polyethylene degradation products by high performance liquid chromatography. J Chromatogr A. 2003; 1003(1-2): 105-112. doi: 10.1016/s0021-9673(03)00760-7

4. Wang Y, Wang L, Lu Q, et al. Analysis of degradation products of polyethylene terephthalate by high-performance liquid chromatography. J Appl Polym Sci. 2013; 127(3): 1802-1809. doi: 10.1002/app.37639

These references provide information on the use of HPLC for analyzing degradation in polymers such as PET, PVC, and PE. They discuss various aspects of the HPLC analysis, including column choice, mobile phase, detection, and sample preparation. Additionally, they provide specific examples of HPLC methods for analyzing degradation products of these polymers.

Ideally, those standards should be generated internally by your own lab or the lab that produces the samples you are testing because those polymers will vary based on the process used, purification steps, and desired target molecular weight and degree of polymerization.

But if needed some material to get started, many manufacturers offer these materials at varying molecular weight (ThermoFisher, MilliporeSigma, etc). You may need to get a few different molecular weights to generate a calibration curve. Many companies like PSS-Polymer can make custom standards.

For the polymers themselves, I would run size exclusion chromatography with refractive index detector and report: %Peak Area of the main peak, %Large Molecular Weight Species or Aggregates, Mw (average molecular weight), and PDI (polydispersity index). If degradation is observed, Mw will go down and PDI will go up.

If you have fancier instrument that has light scattering detector inline (especially MALS) with the refractive index detector, you can do all those above but also obtain intricate size distribution profile of all species.

DLS (such as Malvern instruments) can also be used for aggregation.

For known or expected degradation: These polymers are well resistant to chemical changes so what I described above should be enough but if it's not, you can run a suitability/reference injection of your sample under test but forced degraded. For example, we know PE is prone to degradation under nitric acid. So prepare your sample in strong nitric acid at 60oC and incubate for several hours to 2-5 days, neutralize, then inject to see the peak shape and any new peaks and match to your regular sample prep. This can be done with multiple conditions at once and retain the chromatograms for future use to match the relative retention times and peak shape. On size exclusion column, mostly peak shape changes will be seen as they have low resolution power.