PlastiTrax® QC tablets
| Deuterated Polymers | Deuterated Polystyrene (dPS) | Deuterated Polyethylene (dPE) |
Reliable and reproducible microplastic analysis requires robust and systematically implemented quality control measures (QA/QC). Microplastic particles and related contaminations can now be detected almost everywhere—in environmental samples, laboratory environments, and even in reagents—making the precise evaluation of analytical results increasingly challenging. Particularly in complex matrices, where background contamination or matrix effects may occur, unintended inputs or losses during sample preparation can lead to altered recovery rates and consequently introduce bias into the results.
To specifically address and validate such challenging matrices, we use deuterated polymer fragments (dPE and dPS) as internal quality control standards. These materials do not occur naturally in the environment and can therefore be clearly identified as intentionally added reference particles. Due to their characteristic and clearly distinguishable spectra—both in the infrared and Raman regions—they can be reliably differentiated from conventional environmental microplastics. This makes them ideally suited for recovery assessments, monitoring potential contamination, and implementing automated quality control processes.
By deliberately spiking real samples with a tablet containing a precisely defined number of dPE and dPS particles, recovery can be reliably determined for each individual measurement without additional effort. Any potential bias in recovery rates becomes transparent and can be systematically evaluated. At the same time, deuterated polymers enable the implementation of a fully automated QA/QC system, as their identification is purely spectrum-based and does not require optical recognition (e.g., colored particles or beads). Due to their strong physical similarity to conventional PE and PS in terms of density, morphology, and behavior during sample preparation, they realistically represent actual process conditions and significantly improve the reproducibility and reliability of microplastic analyses.
Benefits and application:
✔ Clearly distinguishable from environmental microplastics (not naturally occurring)
✔ Applicable to all particle-based analytical methods (µFTIR, Raman, and QCL)
✔ Precise recovery determination for different particle size
fractions (25–50, 50–100, and 100–200 µm)
✔ Enables the implementation of an automated QA/QC system
✔ Reduces bias in recovery rates
✔ Suitable for complex and contamination-prone matrices
✔ No optical identification required (no colored fragments or beads needed)
✔ High physical similarity to conventional PE and PS
✔ Defined particle numbers ensuring full traceability
✔ Improved reproducibility and data quality
✔ Traceable quality assurance for routine analyses
Optical comparison of polystyrene (PS)
and deuterated polystyrene (dPS)
The figure shows the 50–100 µm fraction of polystyrene (PS) and deuterated polystyrene (dPS), recorded with an optical microscope on a gold-coated substrate. Both fragments appear optically identical in terms of size, shape, and contrast, highlighting their strong physical similarity. Only spectroscopic analysis allows dPS to be clearly distinguished from conventional PS, making it an ideal internal standard for quality control applications.
Spectral differences in µFT-IR for PS and dPS
Although polystyrene (PS) and deuterated polystyrene (dPS) appear identical under an optical microscope, they exhibit significant spectral differences. These differences arise from isotopic labeling, where hydrogen (¹H) in PS is replaced by deuterium (²H) in dPS. As a result, the C–H vibrations shift to lower wavenumbers and appear as C–D vibrations. This characteristic shift enables the clear spectroscopic identification of dPS and makes it an ideal internal standard for microplastic analysis.
Spectral differences in µFT-IR for PE and dPE
Similar to PS and dPS, polyethylene (PE) and deuterated polyethylene (dPE) exhibit identical physical properties while remaining clearly distinguishable spectrally. The C–H stretching vibrations typically observed above 2800 cm⁻¹ shift to C–D vibrations at lower wavenumbers due to the isotopic substitution of hydrogen with deuterium. This characteristic spectral shift allows dPE to be reliably differentiated from environmental PE, making it well suited as an internal standard for FTIR-based microplastic analysis.
Spectral differences in Raman-spectroscopy
The same phenomenon is also observed in the Raman spectrum. While conventional polystyrene (PS) exhibits characteristic C–H vibrations, these are replaced by C–D vibrations at lower wavenumbers in deuterated polystyrene (dPS). This spectral shift enables clear differentiation between PS and dPS, making dPS an ideal internal standard for microplastic analysis using Raman spectroscopy.
Production of Deuterated Fragments
| Synthese | Bulkpolymerisation | Kryomühle
The synthesis of deuterated polystyrene (dPS) is carried out via thermally initiated radical polymerization of the monomer styrene-d₈, using a radical initiator but without crosslinkers or additives. This process corresponds to the industrial production method used for conventional polystyrene (PS). After polymerization, a solid dPS block is obtained, which is subsequently ground in a cryogenic mill to produce fragments. These fragments are then sieved into different size fractions, resulting in particle suspensions suitable for further applications.
Deuterated polyethylene (dPE) cannot be synthesized in-house due to the gaseous nature of its precursor compounds. It was therefore purchased as a bulk polymer. The subsequent fragmentation was carried out using the same standardized procedure applied to our other polymer materials to ensure comparable particle properties.
