DETERMINATION OF FLAME RETARDANTS BY GAS CHROMATOGRAPHY – MASS SPECTROMETRY


Polybrominated biphenyls (PBBs) and Polybrominated diphenyl ethers (PBDEs) are routinely used as fl ame retardants in electronic equipment, textiles and plastics. These fl ame retardants are deemed a hazardous substance due to the health implications which they cause; they are carcinogenic compounds. PBBs and PBDEs are regularly released into the environment during production and disposal of products which contain these fl ame retardants. As carcinogenic chemicals, the release of PBBs and PBDEs must be controlled and monitored to minimise the amount released into the environment and limit human exposure. The Restriction of Hazardous Substances Directive (RoHS) regulates the levels permitted for use in electronic equipment, typically 0.1% for both PBBs and PBDEs. SCION Instruments developed a method for the analysis of PBBs and PBDEs by gas chromatography with mass spectrometry.


Experimental


A SCION 456 GC was coupled to the SCION Single Quad Mass Spectrometer. The analytical conditions for this analysis can be found in Table 1 with the instrumentation used being found in Figure 1.


Table 1. Analytical conditions of the GC-MS


Conditions S/SL


Column Oven


Carrier Gas Transfer Line Source MS


280°C Scion-5HT 15m x 0.25mm x 0.10µm


110°C (2 mins), 40°C/min to 200°C, 10°C/ min to 260°C, 20°C/min to 340°C (2 min)


Helium 1mL/min constant 300°C 230°C


Full Scan, 100-1000Da


1mL of each PPB and PBDE standard mixtures were prepared in a 5mL volumetric fl asks. Toluene was used to adjust the standard stock solutions to 20µg/mL. Working standards were prepared in


concentrations of 0.05, 0.15, 0.25, 0.35 and 0.45µg/mL for each of the target compounds. Preparation of samples varies depending on the sample type but can include pyrolysis and solvent extraction.


Results


The fi ve working standards were analysed in both full scan and SIM mode, with quantifi cation using SIM mode. The total ion chromatogram (TIC) for a 20µg/mL stock standard was used for peak identifi cation with peak retention times being compared with the certifi cate of analysis to confi rm identifi cation. Figure 2 shows the two total ion chromatograms (TIC) from the 20µg/mL stock standards whilst Table 2 details peak identifi cation, linear coeffi cient values of all calibration curves and repeatability values, in full scan mode. Repeatability of the system was determined through ten replicates of each component at 0.05µg/mL.


Figure 1 Scion GC-MS


It is critical that the instrumentation used can detect both low levels and higher concentrations to determine how much of a risk the fl ame retardant items are to the environment and human health. Excellent linearity was observed for all target compounds, with a calibration range from 0.05µg/mL to 0.45µg/ mL. All coeffi cients were equal to or greater than 0.995. Figure 3 shows the calibration curve of Decabromobiphenyl, which is representative of all target compounds analysed. Linearity was calculated using SIM data.


In addition, excellent repeatability was also observed for all compounds for both retention time and peak area. These low RSD% values are important when monitoring low-level


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