Application SOP/FUI for our PlastiTrax® tablets
| Standard Operating Procedure | Instructions for Use |
Our detailed Instructions for Use (IFU) provide step-by-step guidance for the correct handling and application of PlastiTrax® Reference Tablets. They include recommendations for storage, sample preparation, tablet dissolution, filtration, and quality assurance, ensuring reproducible and reliable results across different microplastic analytical workflows.
1. Storage of PlastiTrax® products
| dry |
Store PlastiTrax® Reference Tablets in a dry environment, protected from excessive humidity and direct light. Although each tablet is individually sealed in a double-layer aluminum foil pouch, proper storage conditions are recommended to ensure optimal handling.
Due to the hygroscopic nature of potassium bromide (KBr), tablets may occasionally appear slightly cloudy or opaque after prolonged exposure to moisture. This is a normal physical effect caused by atmospheric humidity and does not affect the tablet's performance, particle composition, or analytical suitability.
Such tablets can be used without any restrictions.
2. Unpacking
| clean enironment|
To minimize the risk of contamination, it is recommended to perform all unpacking steps in a laminar flow cabinet or a similarly clean laboratory environment.
Carefully cut open the outer packaging along the marked cutting line using clean scissors or a scalpel. Remove the inner aluminum foil pouch using clean tweezers. Do not touch the tablet with your fingers, as this may introduce contamination. Carefully unfold the inner aluminum foil pouch and remove the tablet using tweezers. The tablet is now ready for dissolution and subsequent sample preparation.
3. Tablet dissolution
| spiking |
Transfer the PlastiTrax® Reference Tablet into a clean glass vessel. For optimal contamination control, use laboratory glassware that has been thoroughly cleaned and, where appropriate, heat-treated at >500 °C prior to use.
Add at least 20 mL of filtered water (e.g., 0.22 µm) to the vessel and gently swirl for approximately 1–2 minutes until the potassium bromide (KBr) tablet has completely dissolved. The dissolution releases the microplastic particles into the suspension without altering their properties.
The volume of water may be adjusted according to the expected sample volume or the requirements of the analytical workflow. Once the tablet has completely dissolved, the sample is ready for proceeding.
QC tablets with deuterated Polymers:
Our QC tablets contain deuterated PE (dPE) and PS (dPS) as internal standards. They can be spiked directly into aqueous samples without separate dissolution, enabling recovery monitoring throughout the entire analytical workflow.
4. Sample preparation
| density separation | digestion protocol |
Sample preparation is a critical step when validating analytical workflows for different sample matrices. The spiked sample should be processed according to the laboratory’s established sample preparation workflow for the corresponding sample type. This may include, for example, filtration steps, density separation, and chemical or enzymatic digestion.
It is important that the spiked sample undergoes the same preparation steps as the actual samples to be analyzed. This ensures that particle recovery, potential losses, and method performance can be assessed under realistic and comparable workflow conditions.
Important information:
The use of an ultrasonic bath is strongly discouraged during sample preparation. Ultrasonic treatment has been shown to induce fragmentation of microplastic particles, which can artificially increase the measured particle count and may result in apparent recoveries exceeding 100%. To ensure reliable and reproducible recovery measurements, all sample preparation steps should be performed without the use of ultrasonic agitation.
5. Filtration
| FTIR | Raman |
At the end of the sample preparation workflow, transfer the processed sample onto the filter that will subsequently be used for microplastic detection. Filtration should be performed according to the laboratory’s workflow and using the appropriate filter material for the selected analytical technique.
After the complete sample has been filtered, it is important to rinse the filtration vessel and apparatus first with filtered water before performing the final rinse with filtered ethanol. This step prevents the precipitation of residual potassium bromide (KBr), which may occur if ethanol is added directly. A final rinse with filtered ethanol can then be performed to facilitate drying of the filter prior to analysis.
6. Data analysis
| Recovery | Polymer types|
Following analysis of the filter, the recovery of each polymer can be determined using the particle counts provided on the product label or, where available, on the corresponding Certificate of Analysis (COA).
When evaluating recovery data, please note that differences in reported particle sizes may occur depending on the image analysis software or analytical instrument used. The particle size specified for PlastiTrax® Reference Tablets is based on the minimum Feret diameter (min-Feret), reflecting the sieve-based manufacturing process. In contrast, many analytical systems report the maximum Feret diameter (max-Feret) by default. Consequently, direct comparison of particle size distributions may result in systematic differences.
As part of our quality assurance program, every production batch is thoroughly characterized, with particle measurements routinely performed down to a particle size of 10 µm. While all certified particles are quantified within this measurement range, the presence of additional particles smaller than 10 µm cannot be completely excluded, as they may be generated because of fragmentation processes.