AUTOMATED SIFT-MS continued
Polymer pellet samples were analyzed in ground form. The polyoxymethylene (POM) sample is of particular note—formaldehyde is analyzed di- rectly from this sample within seconds without any derivatization, preconcentration or other pretreatment. Analysis speed leads to very high throughput, providing rapid warning for quality issues; it also greatly reduces the cost per analysis. Applications of automated SIFT-MS headspace analysis include residual monomer or solvent analysis in pharmaceuticals and pack- aging, targeted analysis in foods and beverages and objective sensory screening.
Multiple headspace extraction
(MHE) MHE offers significant advantages over equi- librium SHA when working with solid materials and samples where composition of the matrix varies from sample to sample (e.g., in the analysis of soil samples). With solids, the rate of mass transfer within the material is very low. Equilibrium conditions take so long to achieve that classical static headspace is impractical. Because MHE does not depend on achiev- ing equilibrium between the solid and the headspace, measurements can be made more quickly. Additionally, MHE allows the total VOCs contained within the solid to be calculated, not just the partitioned headspace concentration. This is illustrated using the example of poly- styrene analysis for residual styrene monomer (Figure 4). SIFT-MS rapidly makes the required series of multiple headspace extractions, turn- ing MHE into a practical, routine technique—the serious time penalty associated with slow GC or GC/MS analysis is eliminated. Applications of MHE-SIFT-MS include determination of residual solvents in packaging materials, analysis of thermally labile materials and quantitation of VOCs in soil samples.
Rapid analysis of sample bags and
canisters Comprehensive, direct gas analysis capabilities make SIFT-MS ideally suited to high-through- put analysis of industry-standard gas sampling devices, such as sample bags and canisters. No derivatization, drying or preconcentration is re- quired for direct analysis to pptv levels. Further, reactive and labile compounds are readily de- tected and analyzed before they degrade.
Figure 3 – Residual monomer analysis of different ground polymers, including formaldehyde from POM polymer.
Figure 4 – Automated MHE using SIFT-MS: residual styrene monomer determination in polystyrene (PS) pellets.
Figure 5 – Continuous analysis of fragrance components as they are slowly released from muscle ointment.
AMERICAN LABORATORY 18 JANUARY/FEBRUARY 2017
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