Rapid Analysis of Volatile Compounds in Paperboard Using Direct MS

Pharmaceutical and food products are susceptible to contamination from packaging volatiles – whether from polymeric materials, printing inks, or paperboard.  VOCs can also migrate through multiple layers of packaging, so it is critical to analyze materials regularly.

Traditional approaches utilize static headspace analysis, but it is difficult to relate these results to actual quantities of volatiles in the packaging due to matrix-dependent interactions.  The MHE technique circumvents this issue by calculating the total concentration in the product from a limited number of consecutive headspace analyses (Figure 1).  Typically six cycles are utilized in complete analysis of one sample, which makes it a very costly technique when coupled with gas chromatography-mass spectrometry (GC-MS).  By utilizing rapid SIFT-MS measurement instead, headspace regeneration becomes the rate-limiting step and multiple samples can be analyzed in parallel.

Figure 1. Schematic representation of the MHE technique.

Table 1. Concentrations of volatiles (in µg g-1) found in a paperboard sample using MHE-SIFT-MS. Concentration data, the mean, standard deviation and RSDs for the four replicate analyses are shown.

The data shown here (Table 1) were obtained using a Syft Technologies Voice200ultra SIFT-MS instrument integrated with a GERSTEL Multipurpose Sampler (MPS) (GERSTEL, Mülheim an der Ruhr, Germany) equipped with a GERSTEL agitator/incubator and headspace vial racks.  Replicate paperboard samples (linear dimensions 210 x 40 mm; mass 1.3 grams) were placed in four 20-mL headspace vials and incubated at 75 °C for 20 minutes, followed by a 3-minute post-measurement flush. Headspace was sampled with a 2.5-mL headspace syringe heated to 150 °C, and injected at a flow rate of 50 µL s^-1 into the SIFT-MS instrument’s inlet (total flow rate of ca. 420 µL s^-1). This study demonstrates that MHE-SIFT-MS is a very powerful new technique for rapid determination of volatile compounds in paperboard.  Not only does SIFT-MS provide a four-fold increase in sample throughput compared to MHE-GC-MS, but it also broadens the range of compounds detectable in a single analysis, quantifying polar species such as the small aldehydes without any need for derivatization or pre-concentration.

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