Thermal Extraction of Phthalates in Polymers Based on IEC Method 62321-8 Using a Pyroprobe

This application note presents calibration plots, RSDs, and MDLs for IEC Method 62321-8 using a CDS Model 6150.

Certain phthalate additives are known to be harmful to humans, resulting in regulations regarding their use. With growing environmental awareness and perceptions, the use of phthalates has been restricted in many countries, including the European Union and the United States of America. As a result, a few international standards and conformity assessment bodies such as the International Electrotechnical Commission (IEC) and the American Society for Testing and Materials (ASTM) have published standards for determining certain phthalates in polymeric materials. The recent IEC Method 62321-8 defines approaches to determine di-isobutyl phthalate (DIBP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), bis-2-ethyl hexyl phthalate (DEHP), di-n-octyl phthalate (DNOP), di-isononyl phthalate (DINP), and di-iso-decyl phthalate (DIDP) in electronics using GC–MS and TD–GC–MS.

Experimental Conditions

The samples were pyrolyzed in a CDS Pyroprobe 6150 with an autosampler, equipped with Drop-In-Sample-Chamber (DISC) technology. A DISC tube was used as the sample vessel.

Results

Thermal extraction of additives is a straightforward approach involving only a few steps, and therefore the possibility of greater recovery when compared to solvent extraction techniques exists. Sample is simply placed in a sample tube, and dropped into the DISC of a 6150 Pyroprobe. The Pyroprobe thermally extracts the sample using two sequential temperature ramps as defined in the experimental conditions, straight to a single quadrupole GC–MS instrument. Resulting chromatograms closely match the chromatograms in Annex C.2 of the IEC Method (Figure 1). Calibration curves based on a one-point calibration (as indicated in the method) are also shown in Figure 1.

Figure 1: Calibration curve and chromatograms (TIC and EIC) of phthalates.

The statistical measures related to reproducibility depend on temperature precision, along with sample related issues like homogeneity and sample preparation. Eight replicates a 500 ng phthalate standard provided area RSDs of around 3% for most of the phthalates. Furthermore, when method detection limits were studied in accordance with the IEC method, seven replicates produced calculated MDLs ranging from 9.4 to 21.7 mg/kg, 78–91% lower than the 100 mg/kg requirement (Table I).

Conclusion

The latest version of the Pyroprobe from CDS Analytical ensures repeatable, reliable results for thermal extraction of phthalates in accordance with standard methods, like IEC Method 6321-8 for determination of phthalates in electrotechnical products.

CDS Analytical
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Website: www.cdsanalytical.com