Summary
This Application Note shows that BenchTOF instruments, coupled with GC×GC, can provide a high-performance solution for the detection and quantitation of allergens in complex cosmetics extracts. Revolutionary variable-energy electron ionisation technology was also shown to enhance both the sensitivity and selectivity of analyses by generating mass spectra containing structurally-significant fragment ions with an improved molecular ion signal.
Introduction
In 2003, an EU Directive1 restricting the use of allergenic compounds in fragrances was released. The Directive named a total of 27 allergens, stating that they should be labelled if present at >100 ppm in ‘wash-off’ products (such as shower gels), or >10 ppm in ‘leave-on’ products (such as perfumes). Compliance with this Directive, therefore requires that these compounds are identified and quantified accurately. Two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC–TOF MS) is well-suited for the analysis of allergens within complex cosmetics extracts. The enhanced separation provided by the coupling of two columns of different stationary phase minimises the requirement for tedious sample preparation steps, which can also introduce error into the analytical process.Despite the superior separation afforded by GC×GC, the identification of individual compounds in complex samples remains challenging when multiple compounds in a chemical class have similar spectra, or weak molecular ions. This problem can be addressed by the use of soft ionisation to reduce the degree of ion fragmentation, but this approach has been cumbersome to implement until now. This Application Note describes the use of Select-eV – revolutionary MS source technology that enhances compound identification by enabling efficient electron ionisation at much lower (softer) energy levels without compromising sensitivity. We also show how Select-eV complements the other fundamental advantages of Markes’ BenchTOF time-of-flight mass spectrometers for the GC×GC identification of allergens.Background to BenchTOF instruments
ALMSCO BenchTOF™ time-of-flight mass spectrometers are designed specifically for gas chromatography. They are particularly appropriate for the GC×GC analysis of complex samples, such as cosmetics extracts, because they offer exceptional sensitivity, spectral quality and speed: • Sensitivity: Highly efficient direct-extraction technology allows BenchTOF instruments to acquire full-range spectra with SIM-like sensitivity, allowing them to reliably detect trace-level analytes in a single run, which would be difficult or impossible on a quadrupole instrument.• Spectral quality: The ‘reference-quality’ spectra produced by BenchTOF instruments are a close match for those in commercial libraries such as NIST or Wiley. This enables quick and confident matching of both targets and unknowns.
• Speed: The acquisition rate of 10,000 full-range spectra per second provides sufficient data density to handle the very narrow peaks produced by GC×GC and enhances the performance of the latest automated spectral deconvolution and ‘data-mining’ algorithms.
>> Download the full Application Note as PDF
Newsletters
Receive the latest pathologist news, personalities, education, and career development – weekly to your inbox.
