Stability of methylene chloride spiked passive samplers: an international shipping and transportation study

A stability study was carried out by dynamically spiking Assay Technology Model 541 passive samplers with known amounts of methylene chloride (MeCl2) and shipping them to facilities around the world. Once arrived, these samples remained on site briefly and then were returned to the laboratory in North Chicago, III. A total of 22 sets of samples was prepared. Each sample set contained four passive samplers: blank, low (2.5 ppm), medium (25 ppm), and high (125 ppm) concentrations. Twelve of the 22 sets were separated into 4 groups of 3 sets, with each group defined as a cluster. One cluster was shipped to a pharmaceutical production facility in each country--South Africa, Pakistan, and Indonesia--and then shipped back to the lab, under normal shipping conditions. The fourth cluster was carried by one of the authors, who traveled through all three countries. The remaining 10 sets of samples were kept in the lab as controls. Each returning cluster was analyzed with two lab sets on arrival in the lab. Results obtained were evaluated using a t-test at a 95% confidence level. No significant differences were found in MeCl2 spiked passive samplers between traveled and lab controls, samples stored at room temperature and in the freezer, or analyzed right after being spiked and stored up to 7 weeks. It was concluded that MeCl2 spiked passive samplers were stable for at least 4 weeks at room temperature. There was no impact observed from international shipping and transportation on MeCl2 spiked passive samplers without temperature control.