The FDA Guideline "Pyrogen and Endotoxins Testing: Questions and Answers" indicates that the ability to detect endotoxin can be affected by storage and handling of the sample. As endotoxin molecules are known to absorb to surfaces, the type of sample container is quite relevant. Researchers from Sartorius Stedim Biotech therefore measured recovery of Control Standard Endotoxin (CSE) from rigid containers constructed of polystyrene, polycarbonate, polypropylene and polyethylene terephthalate (PETG) at four different time points across 24 hours.
Sample containers were filled with WFI, heated to 37°C and extracted for 60 minutes at ambient temperature. The extraction liquid was pooled and tested using the kinetic turbidimetric LAL assay.
The authors conclude that polycarbonate or polystyrene collection containers are suggested for the most accurate endotoxin testing results when the assay is conducted within 6 hours of the sampling event. Overall polystyrene is suggested as the preferred sample collection container for endotoxin assays due to its relatively high recovery and stability over time. Nevertheless, as there is significant change in recovery of endotoxin across most materials between 1 and 6 hours after inoculation, they recommend to conduct the endotoxin assay as soon as possible after sampling, preferably within 1 hour of sample collection.
This is a nice study about sample container suitability.
Written by SST
Reference:
Aseptic Sampling Best Practices, Endotoxin Binding Affinity, Sartorius Stedim Biotech GmbH
