Determination of Phthalates in Plastic Bottles and Beverages

Phthalates are commonly used as plasticizers. These compounds help make plastics more flexible and durable. They are commonly found in medical devices, food packaging, household and personal care items. Migration or leaching from these products can lead to exposure for the consumer. Health concerns regarding phthalates have been raised about their potential adverse health effects, especially regarding endocrine disruption.

The GERSTEL Twister is an extraction device used for Stir Bar Sorptive Extraction (SBSE). The Twister enables ultra-trace determination of organic compounds in aqueous and gaseous matrices. It consists of a glass-coated magnetic stir bar coated with an absorbent layer. After sampling, the Twister is placed in an empty TD tube and heated in a thermal desorption system to release the analytes of interest. The advantages of Twister are highly efficient extractions due to the large stationary phase volume, extraction efficiencies are predictable based on octanol/water partition coefficient, solventless extraction and reusable (green technique), more stationary phase than similar devices, and multiple samples can be extracted in parallel. Detection limits in the ppq to ppt range are obtainable using this technique.

Direct thermal extraction (DTE) is a technique in which a solid or liquid sample (in a suitable holder) is heated with inert gas flow, and the analytes evolved are trapped. In an online system, the thermal desorber is used to heat and provide inert gas flow, and the analytes are trapped in the GERSTEL CIS 4 inlet liner. The analytes can be trapped cryogenically or on a sorbent. After analyte trapping is complete, the trap is rapidly heated to transfer the analytes onto the head of the GC column as a narrow band to provide optimum chromatographic performance. A sample size of 10-50 mg is typically used for this technique. The experimental variables that need to be optimized are extraction temperature, extraction time, and flow rate across the sample. Since there is minimal dilution (split) of the analytes before entering the GC column, this technique can provide very low detection limits, even with the relatively small sample size.

The GERSTEL MultiPurpose robotic sampler (MPS) with a TD 3.5+ thermal desorber, in combination with the GERSTEL Cooled Injection System (CIS 4), fully automates thermal desorption for the determination of phthalates in plastic and beverages. An Agilent 8890 gas chromatograph with 7000E TQ was used for the separation and detection of the phthalates.