Synthesis and characterization of eight single chain length chlorinated paraffin standards and their use for quantification.

RATIONALE

Quantification of chlorinated paraffins (CPs) via gas chromatography coupled with electron capture negative ionization low-resolution mass spectrometry (GC/ECNI-MS) is a very common practice, although the quality of the results has been disputed due to insufficient mass resolution and the strong impact of the degree of chlorination on the GC/ECNI-MS response.

METHODS

For further tests we synthesized eight single chain length CP standards (C -C ) with chlorine contents between 51.1% and 61.3%. The individual single chain length standards, 1 + 1 mixtures of two chain length standards and self-prepared mixtures of short-chain and medium-chain CPs were quantified by linear regression according to a previously reported method (method 1) as well as by exponential regression (method 2).

RESULTS

Concentrations obtained from single chain length CP standards deviated between -74% and 152% from the target value. However, the error became smaller when self-prepared CP mixes with two and four chain lengths were analysed. For short-chain CP (SCCP) mixture analysis, both methods produced good results (<25% deviation from the target value). In the case of medium-chain CP (MCCP) mixtures, however, method 2 (17-34% deviation) was more accurate than method 1 (43-52% deviation).

CONCLUSIONS

Both methods 1 and 2 are fit for GC/ECNI-MS analysis of SCCP mixtures, while the improved method 2 is recommended for quantification of MCCP mixtures.