Use of Heated Headspace and GC/MS to Analyze Finished Plastic Products

Topics Covered

Introduction
Experimental Design
Results
Conclusion
References

An automated head space auto sampler is typically applied to analyse a raw sample or segment of finished material for the presence of volatile compounds. With little or no sample preparation involved using the auto sampler, high-quality control testing is possible for material in the manufacturing industry.

The Bruker SCION SQ single quadrupole mass spectrometer is a synchronomous SIM/Scan mode, which allows for quantitative data reflecting the content of non-target compounds from a given sample.

Introduction

Industrial handling of chemicals and gases means that the application of sampling methods for the detection of volatile organic chemicals is fundamental for the health and safety of consumers, and particularly important where materials such as plastic are being applied in manufacturing techniques that expose this type of material to extreme temperatures in limited or no ventilated areas (for example, the application of certain types of plastic in automobiles that are prone to high temperatures due to sun exposure from the environment).

Volatile organic chemicals are typically used for the manufacturing of interior furnishings, such as as carpets, and polyvinyl chloride (PVC) in piping material, both of which are commonly used in houses that, if not well ventialted, may force volatile organic chemicals to build up to toxic levels in a confined living space posing a heath risk.

Chlorinated solvents, such as dichloromethan, trichloroethane, trichloroethane, and tetrachloroethene have an integral role in industrial and commercial industries. With chlorinated compounds having a relatively low boiling point, they are economical and have properties that make them useful for degreasing fats, oils, waxes, and resins. They are used widely and have been manufactured in large quantities.

Chlorinated solvents are considered to be carcinogenic and are released as a bi-product of industrial practices and are highly hazardrous to the envirmonment. Other compounds detected may be uncharacterized with little known about their toxicity. Certain chlorinated compounds have been associated with human toxicity such as phthalate esters, which have been linked to endocrine disruption in certain animal species; however, regulations are emerging to enforce better control of using such toxic substances for the manufacturing of  plastic bottles.¹

Experimental Design

This study involved samples of polypropylene from a car manufacturer and PVC pipe that were then cut into small pieces and placed directly into 20mL head space vials. About 500mg-1g was added. The Bruker SHS-40 Auto sampler conditions used are cited in Table 1.

Table 1. SHS-40 Sampling Conditions.

Figure 1. Bruker SHS-40 Headspace Autosampler (left) with SCION GC/MS.

The SCION GC/MS column, oven program, and injector conditions:

Results

A full scan of the polypropylene dash board sample was analysed in this experimental study. Figure 2 illustrates all compounds that were tentatively identified using an automated library search against the NIST 08 library.

Figure 2. Full Scan Identification of Compounds in Polypropylene Sample.

Table 2. List of compounds detected in polypropylene dashboard sample.

Table 3. Synchronous SIM/SCAN parameters.

Table 4. Tentatively Identified compounds in PVC sample.

The PVC sample was run in SIM/Scan mode. Figure 3 shows detection of 1,2-dichloroethane, a target compound with qualifier ion.

Figure 3. SIM/Scan analysis of PVC sample.

Figure 4. RIC of PVC sample.

The compounds were tentatively identified and are listed in Table 3. Lower display is magnification of peaks eluting between 10 and 14 min.

Conclusion

The findings demonstrate that the Bruker SHS-40 headspace coupled with the SCION GC/MS is an excellent tool for qualitiative and quantitative identification of volatile compounds in raw materials. Using SIM, compounds can be selectively quantitated at very low concentrations. Full scan data can be interrogated for TICs and used for quality control “fingerprints”.

This information has been sourced and adapated from Information provided by Bruker CAM.

For more information please contact Bruker CAM

References

1. Developmental Effects of Endocrine-disrupting Chemicals in Wildlife and Humans; T. Colborn, F. S. vom Saal, and A. M. Soto, W. Alton Jones Foundation, Washington, DC 20037.