Storage Stability of Odorants in Nalophan^TM Bags: Effect of Storage Condition on Recovery

Sample storage is a key factor in odour quantification. This study investigates the loss of odorous compounds in Nalophan™ sampling bags during storage, simulating real-world transport and storage conditions. The goal was to quantify compound leakage over time by varying operational parameters to identify the most significant losses. The tested compounds—sulphur, oxygenated, and hydrocarbon VOCs—were prepared in the laboratory at 10 ppm. Tests were conducted on 12 L Nalophan™ bags with sampling intervals of 0, 6, 30, 48, and 100 h, exceeding the EN 13725 guideline limits (30 h). To evaluate recovery, environmental and internal humidity and temperature were varied. Additionally, the adsorption surface was increased by inserting Nalophan™ flakes inside the bags. The results show that under ambient conditions, losses during 30 h are contained and are within the order of instrumental uncertainty for all the tested compounds. A higher ambient temperature and humidity did not significantly affect recovery. In contrast, internal humidity appeared to have a more noticeable effect, particularly affecting low molecular weight sulphur compounds and oxygenates. These findings suggest optimal storage strategies for olfactometric samples, highlighting that significant losses do not occur within the EN 13725:2022 storage time limits. Moreover, even exceeding these time limits, the observed losses remain limited to 100 h.