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stability agrochemicals

Agrochemical Formulations

feb 24 2020

Agrochemicals, such as fertilizers, and pesticides are big businesses. Since 2012total pesticide sales have remained relatively stable within the EU, with over 300M kg of pesticides alone being sold in 20162. The market has been moving towards growing demands of organic nutrition and higher concentration pesticides. Reducing our dependence on agrochemicals without posing risks to food security is challenging because pesticides, fertilizers and growth hormones all help to ensure improved and consistent crop yields.3

Given the health concerns surrounding many agrochemical products and the challenges to reduce our dependence on these chemicals, many current efforts are focusing on developing new chemical species that are safer and more environmentally friendly4 and provide higher resistance to bacterial species. Growing demand from an ever-expanding population with decreasing availability of fertile soil is also adding pressure to find ways to increase crop yields. Different approaches to formulation and delivery systems are also required as some of the current challenges are finding ways to more efficiently and effectively deliver pesticides (by having a more targeted release, higher concentrations).

Application Properties 

To treat crops, such as beetroot, maize, and wheat, often oil is a necessary component of the agrochemical. This is because the oily species help to increase the penetration of the pesticides through the leaves. One way of preparing pesticides is an emulsion, where the oil must easily disperse in water and remain stable for the duration of product life cycle .

While they are stored in high concentrations, many agrochemicals will also be used in a dilute form in the field, so any emulsion must remain stable under a range of concentration conditions as well.5 

By embedding the agrochemical in a polymer matrix, encapsulated agrochemicals have slower release mechanisms which help to minimize environmental impact and it is hoped that this will be further improved into ‘smart’ delivery systems, where chemicals are only released as and when needed.8

Other forms of pesticides include flowable or suspension concentrates, suspo-emulsions, wettable powders, and water-dispersible granules. Each has its advantages, for example, dispersible granules tend to flow very easily. The most appropriate formulation is somewhat dependent on the molecular species of interest. 

Testing Technology

To assess whether a formulation is suitable for use for real applications, careful testing needs to be carried out. Turbiscan technology has been used to perform analysis of a new agrochemical based on natural products.5 The Turbiscan allowed testing of products under realistic storage conditions (without dilution or mechanical stress) and the emulsion can be optimized to create a more stable product, using more natural ingredients.

Another advantage of Formulaction’s Turbiscan technology for stability analysis is an incredibly fast testing time. Stability measurements can be performed in a matter of hours or days, making it increasingly straightforward to screen a greater variety of formulation conditions for product optimization. Turbiscan devices are suitable for micro or nano-encapsulated agrochemicals6 as well as a variety of emulsion types.7

The Turbiscan is based on Static Multiple Light Scattering, where analysis of the transmitted and backscattered 880 nm light can be used to monitor particle size and concentration.9, 10 By using this information, the Turbiscan can carry out a variety of stability measurements, including of migration velocity and aggregation, but to help simplify measurements for faster analysis, a parameter called the ‘Turbiscan Stability Index’ is supplied. This is a single number calculated from a range of parameters that allows for rapid ranking and comparison of the stability of samples.10

Owing to their expertise in both quantitative, nondestructive testing of complex products and formulation, Formulaction offers a range of possibilities for the identification and improvement of the formulation of agrochemicals and pesticides. 

References and Further Reading
1. European Environment Agency, (2019)
2. Eurostat, (2019)
3. Liu, Y., Pan, X., & Li, J. (2014). A 1961–2010 record of fertilizer use, pesticide application and cereal yields: a review. Agronomy for Sustainable Development35(1), 83–93. 
4. Popp, J., Pető, K., & Nagy, J. (2013). Pesticide productivity and food security. A review. Agronomy for Sustainable Development33(1), 243–255. 
5. Formulaction Data Sheet (2019)
6. Feng, J., Shi, Y., Yu, Q., Sun, C., & Yang, G. (2016). Effect of emulsifying process on stability of pesticide nanoemulsions. Colloids and Surfaces A: Physicochemical and Engineering Aspects
7. Zheng, L., Cao, C., Li, R., Cao, L., Zhou, Z., Li, M., & Huang, Q. (2017). Preparation and characterization of water-in-oil emulsions of isoprothiolane. Colloids and Surfaces A: Physicochemical and Engineering Aspects
8. Sinha, T., Bhagwatwar, P., & Krishnamoorthy, C., Polymer Based Micro- and Nanoencapsulation of Agrochemicals, 5–28. 
9. García, M.C., Alfaro, M.C., Calero, N., Muñoz J., (2014) Influence of polysaccharides on the rheology and stabilization of α-pinene emulsions, Carbohydr. Polym., 105, 177–183.
10. Turbiscan Product Page (2019)

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