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Analysis of chemical substances in balloons

6 Supplementary identification by GC/MS-headspace analysis

• 6.1 Verification by GC/MS-headspace analysis at 150 °C
  • 6.1.1 Introduction
  • 6.1.2 Method
  • 6.1.3 Results from the verification analysis
• 6.2 Headspace analysis at 80 °C

6.1 Verification by GC/MS-headspace analysis at 150 °C

6.1.1 Introduction

As there was no unambiguous verification of accelerators by the thin layer chromatography, a headspace analysis at GC/MS at 150 °C was carried out on the balloons selected for analysis for nitrosamines and nitrosatable substances. At this temperature the accelerators will decompose and the decomposition products can give information about the accelerator types applied.

6.1.2 Method

The analysis is performed by headspace GC/MS at 150 °C after one hour’s exposure. The numerous different chemical substances formed and identified by the analysis have not been quantified. The relative amount of the chemical substances has instead been valuated from the area percentages in the chromatogram.

6.1.3 Results from the verification analysis

The number of organic compounds detected by the GC/MS verification analysis at 150 °C appears from Table 6.1.

Table 6.1 Headspace analysis 150 °C of 4 selected balloons

As can be seen from Table 6.1 there are many different substance types, some originating from the used accelerators, others may be formed from the colorants. Balloon no. 16 is producing the most different substances in the headspace, i.a. chlorobenzene, benzene, aniline, and dibutylnitrosamine. These substances are not liberated in measurable amounts from the other balloons. Balloon no. 16 was bought in a discount shop.

All samples liberated carbon disulfide, largest amount from balloon no. 6 and smallest amount from balloon no. 20.

N,N-dibytylformamide was liberated from balloons nos. 3, 16, and 20. It is a typical degradation product from the zinc salt of dibutyldithiocarbamate. Balloon no. 16 is also liberating dibutylamine and the corresponding nitrosocompound. Dimethylamine is released from balloon no. 6 and dimethylformamide from all four balloons. It is a typical degradation product from derivates of dimethyldithiocarbamine acid.

6.2 Headspace analysis at 80 °C

An analysis of the liberated substances in headspace at 80 °C was performed. At this temperature only a minor decomposition of the added rubber chemicals will occur. The analysis results appear from Table 6.2.

Table 6.2 Concentration of volatile substances in headspace at 80 C in µg

As can be seen only few volatile chemical substances are liberated at 80 °C. From previous studies it is known that carbon disulfide and dibutylamine are degradation products from zinc dibutyldithiocarbamate and that both are found in the rubber in spite of the low boiling point of carbondisulfide. BHT is a frequently applied and relatively volatile anti-oxidant and 1,2-ethandiol find use as a dispersing agent/ancillary substance. Hydrocarbons liberated may originate from the applied colorants.

There is a good matching between the results from degassing at 80 °C and at 150 °C, as the relative amount of volatile chemical substances detected at the low temperature are reflected in the chromatograms (lower area counts).

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Version 1.0 December 2007, © Danish Environmental Protection Agency