Extracting mycotoxins with water –can that work?

In order to make mycotoxins “available” for testing in an assay, they need to be extracted from ground samples. During the extraction process, mycotoxins encased in the grain kernel are transferred into a liquid, usually with the help of organic solvents that are hazardous substances, harmful to both the operator and the environment.

By Philipp GRUBER, Product Manager, Romer Labs

Why hasn’t water been used from the very beginning?

While fumonisin and deoxynivalenol are easily extracted using water, other mycotoxins like aflatoxins or zearalenone are not very water soluble.

This has led to the use of hazardous organic solvents like chloroform, acetonitrile and methanol in the extraction process, although laboratories are well aware of the downsides of using solvents, such as their high purchase and disposal costs, and issues associated with environment and operator safety.

To utilize water efficiently in an extraction process, some basics should first be understood.

The polarity of substances

The transfer of mycotoxins from grains into a liquid is not as easy as it seems. It depends foremost on the physical properties of the mycotoxin to be extracted, with polarity playing a major role in this context.

As the building blocks of molecules, atoms and how they are arranged can exhibit different electrical charges. Mycotoxins can exhibit positive charges on one side and negative charges on the other. In such cases, the molecule has electrical poles and is called polar.

As such, all substances including mycotoxins, are organized into three major groups:

1) Polar substances like water

2) Nonpolar substances like oil

3) Amphiphilic substances like soap that have both polar and nonpolar properties

Polar molecules are also called “hydrophilic” from the Greek word “water loving”, as they are soluble in water. Their attraction to each other is based on their electrical charges. The negative pole of one molecule is electrostatically attracted to the positive pole of another molecule. This sticking to each other is the reason why they are miscible.

Salt and sugar are examples of solid polar substances. Sugar is perfectly soluble in liquids like coffee, but also attracts moisture from the air. For the same reason, salts are often used as desiccants.

On the other hand, nonpolar molecules are called hydrophobic or “water fearing”. Their attraction to each other is a result of a joint repulsion of water and other polar substances. Amphiphilic molecules have both nonpolar and polar properties. Soap, for example, can attract greasy (nonpolar) stains from skin, hair or clothes and at the same time, bind to water (polar) to wash them off.

The search for a harmless extraction solution

To avoid the use of organic solvents, researchers are on the look-out for safe and harmless ways to extract mycotoxins. Detergents dissolved in water have turned out to be a promising solution. Detergents, like soaps, are amphiphilic substances. Their dual nature facilitates the mixture of nonpolar compounds like aflatoxins with water.

At the molecular level, detergents group themselves around the nonpolar mycotoxin with their nonpolar part, while the polar water-soluble part remains in the water. This characteristic allows detergents to literally leach out nonpolar mycotoxins from solid food or feed into water.

A great benefit of such a method is that detergents extract nonpolar substances while the water in which the detergents are dissolved extract polar substances. In this way, one extraction can be used to dissolve various mycotoxins with different physical properties into a liquid.

WATEX - The green solution that works

Due to the different types of mycotoxins and their respective polarities, water alone can’t be the solution. It is the combination of water and detergents (in the form of soluble buffer bags) that is capable of extracting multiple mycotoxins with diverse chemical properties.

With the extraction buffer free of any hazardous substances, operators can conduct safe and fast mycotoxin analyses without harming the environment.

What do washing clothes and extracting mycotoxins have in common?

When clothes are washed, oil droplets that contain dirt particles (a) need to be removed.

By adding a detergent during the wash cycle, soap molecules mix with water and get into contact with the textile fabric (b).

The “oil loving” (hydrophobic) ends of the soap molecules are attached to the oil/dirt while their water loving (hydrophilic) ends remain in the water. When many soap molecules are attached, the oil particle is fully en- closed and a vesicle forms that is soluble in water (c). The tumbling motion during the wash cycle beats those oil containing vesicles in the wash water and removes them from the textile fabric. Just as hydrophobic dirt particles are removed from textile fabric, hydrophobic mycotoxins are removed from grain particles. The shaking motion during extraction moves the encapsulated mycotoxin vesicles into the extraction liquid, making it accessible for detection.