Quantitative Analysis

Owing to the attractive flavour and nutritional characteristics (e.g., it actively lowers LDL cholesterol, aids blood pressure and sugar regulation), olive oil has long been vulnerable to fraud.

Despite the efforts of regulation agencies, like the International Olive Council (IOC) or the US Department of Agriculture (USDA), olive remains susceptible to fraudulent alterations.  This adulteration is often innocuous; cheaper, inferior oils are passed off as expensive authentic olive oil samples.  In some cases, however, it can be lethal – such as the 1981 Toxic Oil Syndrome outbreak in Spain when hundreds of people died from consuming oil with aniline contaminants.

Typical methods to determine olive oil adulteration are based on hyphenated chromatography-mass spectrometry techniques, such as liquid- or gas- chromatography.  These methods can be time consuming, requiring extensive sample preparation and data interpretation.  Moreover, depending upon the scope of the method being used, it can be possible to miss certain contaminants if, for example, they have different retention times or are much more volatile.

NMR Spectroscopy can be a useful alternative technique given that sample preparation is very simple and unique each chemical component in a sample will have a unique chemical signature that is independent of the response factor, the retention time, etc..

We’ve put together an application note highlighting the ability of the NMReady to determine the amount of soybean oil added authentic extra virgin olive oil (EVOO).  As both oils are composed almost entirely of triglycerides with fatty acid chains, the main difference between the two samples is the relative composition of these fatty acid components.  Olive oil consists primarily of monounsaturated fats, so it’s bis-allylic region is expected to be of low intensity relative to soybean oil which has a much higher composition of linoleic (omega-6, C(18:2)) and oleic (omega-9, C(18:3)) acids.

By extracting the percent composition of bis-allylic from each spectrum and plotting this relative to the amount of known adulteration, a calibration curve can be prepared.  Please see the full application note here.

The adulteration of olive oil is only one potential application for the NMReady-60.  For more information on this, or for other ideas of how to include a benchtop NMR spectrometer into your daily workflow for food science or other industrial applications, please contact us!