Craig Butt explains a non-targeted omics approach to characterizing and profiling compounds in citrus oil

Read time: 4 minutes

There is increasing interest among consumers in the benefits of natural products containing citrus beyond the traditionally known benefits of vitamin C. It’s also understandable for consumers to assume that all foods and products labeled natural are, indeed, natural and that they are safe to use.

There’s more to this than meets the eye, however. For example, the presence of chemicals such as pesticides generally disqualifies products from being considered natural, and manufacturers sometimes unintentionally mislabel their products and neglect to mention pesticides or added ingredients. This is a common problem in the “all-natural” essential oil industry, and this is where natural product profiling comes in. Natural product profiling is a type of analysis that can help inform you about the relative amounts of potentially beneficial compounds in a product, as well as any chemicals that are present.

In a recent webinar, which is now available on demand, our in-house expert Craig Butt shows viewers how to use an omics approach to analyze citrus oil in natural products and to detect contaminants such as pesticides. He also demonstrates how to use the analytical capabilities of a quadrupole time-of-flight (QTOF) system powered by SCIEX OS Software to generate quantitative data to identify and quantify contaminants.

Here, Craig answers some of the top questions from the webinar.

1. What are the unique benefits of using a QTOF instrument?

Flexibility and diversity of workflows are key benefits. A QTOF system can do targeted MRM^HR acquisition and non-targeted acquisition with suspect screening as well as unknown identification.

• What are the advantages of using non-targeted “screening” versus “targeted” acquisition?

Screening methods, such as SWATH® Acquisition, acquire data on all of the sample’s detectable compounds. Nothing is missed, provided that the compound is ionized. Also, screening methods allow for the retrospective analysis of previously acquired samples so that reinjection is not required.

• How is SWATH Acquisition different from information-dependent acquisition (IDA)? Can it be routinely used for identification?

SWATH Acquisition collects MS/MS scans on all precursors, thus ensuring the fragmentation patterns are obtained for every detectable compound in the sample. This is important because MS/MS scans are used for compound confirmation or unknown identification.

In the webinar, I make a case where it is applicable in a real-world matrix, particularly for something as potentially dirty as citrus oil. It is powerful. I’ve demonstrated a couple of techniques where we shrink those variable windows so that you have the smallest SWATH Acquisition windows during the highest precursor density to give you the cleanest spectrum.

• Can SWATH Acquisition MS/MS fragmentation spectra be used for compound identification?

Absolutely. The use of variable window SWATH Acquisition enables optimization of acquisition to match the matrix and reduces MS/MS spectra’s complexity. Further, the deconvolution tools in SCIEX OS Software removes background interferences. Both techniques result in improved MS/MS library matching for compound identification.

• Does it take a long time to process samples for “suspect screening”?

Not at all. The use of qualitative filters in SCIEX OS Software (such as precursor mass accuracy, isotope difference and MS/MS library match) significantly speeds the data review.

• How much resolution is needed to remove matrix interferences from the chromatogram?

The ~30,000 mass resolution of the X500R QTOF System removed the citrus oil interferences, resulting in the low background and unambiguous compound identification. The advantage of the X500R QTOF System is that the fast scanning speed does not sacrifice cycle time.

You can check out the webinar on demand here. If you have any questions, feel free to leave a comment here, or you can drop Craig an email at craig.butt@sciex.com.