Investigating the New Year's Eve effect: Analysis of the presence and persistence of pyrotechnic explosive related ions in the background using IC-ESI-MS

The custom of the Dutch to ignite a lot of fireworks at New Year’s Eve (NYE) may cause problems in the interpretations in forensic explosive casework. Similar compounds as encountered in casework will fall back to earth, likely increasing the background levels of these ions. This study determined the presence, significance and relevance of this effect which we named the New Year’s Eve Effect (NYEE). Employees of the Explosives group of the Netherlands Forensic Institute (NFI) collected samples before NYE (reference) and at 7 intervals in January by swabbing an A5 sized surface on different objects using an isopropanol swab. After sample preparation according to a standard procedure of the NFI, the samples were analysed using a new state-of-the-art ACN-enhanced stepwise gradient ion chromatography coupled to electron spray ionisation mass spectrometry (IC-ESI-MS) anion method. It is observed that the NYEE is present and tendencies can be recognized for ions relatable to fireworks like chloride, nitrate, sulfate, thiocyanate, thiosulfate, chlorate and perchlorate. Although the effect is present, only 1 out of 84 changes in ionic concentrations analysed seems to be statistically significant. The significant change is found for perchlorate present on lamp posts. These results are obtained under the specific conditions as present during this study. Whether the effect has an impact on forensic casework depends in the case related context, less decreasing influences or higher pyrotechnic activity will lead to a higher significance and therefore larger possible impact on case work