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Cloud-point extraction to test toxic metals in food and water

Cloud-point extraction is a simple, rapid and environment friendly extraction and pre-concentration of targeted analytes using surfactants as extractant. It does not cause secondary pollution to environment. It is a very fast and sensitive method to detect the presence of toxic metals in food and water.

Food, we eat and water which we drink are two most primary source of nutrition for us. Food provides lots of nutrients to us like carbohydrates, proteins, lipids, vitamins & minerals, and other micronutrients. Whereas, water enriches our body with essential minerals. All these nutrients have their specific function in our body like providing energy, building blocks for repair and growth and also help to regulate chemical processes. Cloud-point extraction is beneficial to detect the presence of toxic metals in food and water.

Need for Cloud-point extraction

Like other nutrients, minerals are also important for us which helps our body to grow, develop, and stay healthy. It also makes our body strong. Some of the common minerals are calcium (Ca), zinc (Zn), and iron (Fe) etc. We know about their functions and importance for our body. But apart from these essential metals, our food may contain some traces of toxic metals such as lead (Pb), arsenic (As), cadmium (Cd), and thallium (Tl). These metals are toxic even at very low concentrations. Hexavalent compounds of As, Cd, and Cr are also recognized as carcinogens by International Agency for Research on Cancer (IARC) and US National Toxicology Program (NTP) recognized .

To detect the presence of these toxic metals in food and water, researchers at the University of Johannesburg developed rapid, efficient, and economical method. It directly identify toxic and carcinogenic metals in vegetables and drinking water.


Method used to detect toxic metals

This new method uses ultra-sound assisted cloud-point extraction and dispersive micro-solid phase extraction to quickly identify the presence of trace metals in some of the vegetables and water. With this method it would be possible to test for several metals at the same time with the possibility for automation to be added. The ultra-sound assisted cloud-point extraction and dispersive micro-solid phase extraction are inductively coupled with plasma optical emission spectrometry. It directly analyze the pre-concentration of As, Cd, Cr, Co, Sb, Pb, and Tl in samples of vegetables and water. These data can be uses as references, which are the maximum allowable levels in common vegetables and potable water.


What is Cloud-point extraction?

Cloud-point extraction is a simple, rapid, and environment friendly extraction and pre-concentration of targeted analytes using surfactants as extractant such as non-ionic and anionic surfactants etc. The aqueous surfactant solution becomes cloudy. It separate into two phases under optimum conditions such as temperature, pressure, and concentration. The two phases are aqueous and surfactant-rich phase. The targeted analytes are concentrated into surfactant-rich phase.


What is Dispersive micro-solid phase extraction?

Dispersive micro-solid phase extraction is a simple and powerful sample preparation technique. It allows fast isolation of the target compounds from the solution. It is based on the efficient dispersion of a sorbent into the sample. There are various dispersion approaches that are used in this technique which allows a close contact between the sorbent and the donor sample solution.


Detection of trace metals using Cloud-point extraction

To determine the level of trace metals, solid vegetable samples convert into liquid form that makes it possible to analyze the metal directly with suitable instrument. Due to this direct analysis, more samples can be analyzed at the same time. It makes the process quicker and time efficient. In this method, clay-based absorbent is combined with cloud-point extraction method for simultaneous analysis of trace metals in vegetables and water samples.

It is an environment friendly methods which conforms to green analytical chemistry principles. It does not cause secondary pollution. This is fast and sensitive method which can be most suitable for small laboratories having limited resources.


Benefited for food safety & quality

Vegetables are vital part of human nutrition which contains most of the micro-nutrients. It also contain trace metals which our body needs. But high dose of those metals cause various health problems. Most of the toxic metal comes in the vegetables from the fertilizers and soil. So, it is very important to know the level of trace metals in our diet.

Trace metals in our food cannot be measured directly during quality testing as no such method have developed. So, very complex and sophisticated technology with vast equipments are required to find the presence of these trace metals which can be time extensive too. This means the determination of trace metals in foods are very slow process which can never be suitable for agricultural produce. So, this method would provide easy and quick determination of those metals. And, it will help to improve food quality for consumers.

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