Karl Fischer Moisture Testing of Recycled Polyethylene Terephthalate
Coulometric Karl Fischer testing with oven desorption at 170 °C isolates true water content in rPET below 50 ppm, preventing costly IV degradation during melt processing.
Septum Vial Sampling
Meaning
Method of extracting a representative portion of a liquid or gas from a sealed container using a needle and a self-sealing membrane. Septum vial sampling allows for the analysis of volatiles or moisture levels in resin additives and solvents without exposing the bulk material to air. The septum maintains the internal environment after the needle is withdrawn.
Analytical Precision
Laboratories use this technique to prepare samples for gas chromatography or moisture analysis. During septum vial sampling, the integrity of the sample is preserved by preventing the escape of light fractions. This ensures the data reflects the true state of the material.
Process Monitoring
Quality control teams use septum vial sampling to check the concentration of stabilizers or lubricants in a liquid blend. The needle must be cleaned between uses to prevent cross-contamination. This method is common in the testing of specialized polymer coatings.
Periodic sampling prevents the use of contaminated batches in production. Sampling frequency depends on the stability of the chemical being tested.
Containment Security
The use of a thick elastomer ensures that the vial remains leak-proof after multiple punctures. Choosing the right material for the septum prevents chemical reactions between the seal and the sample. This reliability is essential for long-term stability testing.