Quantification of Odour Sample Concentration Loss During Transport
nalophane (Nalophan) bags have been used in odour sampling in Australia for over 15 years. Recently there has been suggestions that sample is being lost (by a factor of 10 or more in concentration)when the sample remains in the bag for extended periods of time (hours), especially when samples are shipped by air freight.
Previous studies have been undertaken to investigate whether Nalophane bags lose concentration of pollutant over time. A recent study looked at the H2S concentration lost from wastewater odour samples over one day and shipping by airplane. The study concluded that on average the concentration lost was about 10% of the concentration at time of sampling.
Quantification of the degree of odour sample loss allows users of the odour concentration data to have confidence in the data. Further work is required to undertsand whether the H2S loss is due to chemical reactions within the sample bag or through sample leakage.