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From »The Analytical Scientist« (Issue 20, September 2014). (9/14). "Pesticide Industry Insider. By Sergio Nanita, Principal Investigator at DuPont Crop Protection R&D".

Organisation Organisation DuPont Crop Protection
  Group DuPont (Group)
Products Product pesticide
  Product 2 pesticide analysis
     


Sergio Nanita is principal investigator at DuPont Crop Protection R&D, where he leads analytical and environmental chemistry projects that support the discovery, development, registration and launch of novel agricultural products. Here, he adds an industry perspective to the mix.


The global population outlook makes agricultural efficiency and food security more important than ever. Pesticide analysis is central in the enforcement of regulations to ensure compliance in the use of agricultural products. Pesticide analysis is also essential across all stages of discovery and development of novel agrochemicals, which, together with other modern tools and practices, will address the agricultural challenges of the future. Novel agricultural chemicals are designed to meet modern standards. Today, new active ingredients are expected to replace obsolete chemistries and provide farmers with pest control options that are better in several aspects, including environmental profile, risk reduction and efficacy. Pesticide analysis benefits the greater scientific community and society in many ways, and contributes to fulfilling global food security needs.


Driving analytical science

An often overlooked contribution made by pesticide analytical research is the fact that it has consistently led to the development of broadly-applicable methods; thus, contributing to the broader field of analytical chemistry. I believe that this has occurred in part due to the complexity of the samples typically encountered in pesticide residue analysis. Methods developed to provide reliable analysis of difficult matrices, such as canola seed, dried tea leaves and spices, often work well for simpler systems. In other words, methodologies that pass "the pesticide residue analysis test" are often suited for other purposes. For example, methods by Hans Mol and coworkers have allowed multi-scope analysis to be possible, covering mycotoxins, veterinary drugs and pesticides in a single analytical run, and the QuEChERS method originally introduced by Anastassiades, Lehotay and coworkers has expanded far beyond pesticide residue laboratories.

On the other hand, pesticide residue analysis often demands the best technology. We enjoy today's state-of-the-art thanks to several milestones by many analytical researchers. In my opinion, (i) the use of electrospray ionization in commercial mass spectrometers, (ii) large-scale multiresidue methods, and (iii) the routine use of sensitivity in analytical instrumentation toward simplification of sample preparation, represent key milestones in the 1990s, 2000s and 2010s, respectively. Electrospray ionization was an important milestone because it allowed LC-MS to be a reliable and highly sensitive technique for analyzing non-volatile pesticides that are not amenable to GC.

Regarding instrumentation sensitivity: the well-known "dilute-and-shoot" approach was made possible by the sub-part-per-billion sensitivity that can be obtained routinely with modern mass spectrometers. Therefore, dilution (a straightforward and high-throughput procedure) has become the preferred method for reduction of matrix in complex extracts prior to analysis.


Current trends

As kindly noted by Lutz Alder, over the past few decades, we have seen the addition of new analytical techniques employed in pesticide residue analysis, as well as the evolution and improvement of classical methods. Today, LC-UV has nearly disappeared from pesticide residue analysis, but continues to be an important technique in process chemistry and manufacturing quality control (for example, active ingredient purity assays and impurity analysis). On the other hand, GC-MS is more than 50 years old and continues to be a useful technique for trace-level analysis. A common trend with all techniques is that instruments are more sensitive and rugged today, which has allowed for simpler sample preparation methods. Similarly, analytical instruments rely more on sophisticated software applications to acquire and process data, making chemical analysis more efficient overall - from sampling to reported result. Another clear trend also continues to be seen; simpler, faster procedures that consume fewer resources (solvents, energy, laboratory personnel time) and generate less chemical waste are highly preferred. Consequently, the use of automation in sample preparation has widened (see page 16 for the continued discussion on the importance of sample prep). Test kits for sample preparation, such as commercially available QuEChERS, have improved laboratory efficiency and also reduced the frequency of operational errors.

In summary, instrumentation is more complex, but the procedures are simpler, thanks to advances in computing and sample preparation techniques. The result? A single analytical chemist can do more today than ever before.


Future drivers

I believe that the primary trend of faster and simpler methods for pesticide residue analysis will continue, likely driven by several factors, such as increasing demand for chemical analysis, judicious/selective spending at laboratories across all sectors, and the need to reduce the environmental footprint of testing facilities.

Collaborative and interdisciplinary research efforts are at an all-time high. Consequently, access to (and the advancement of) emerging techniques will continue to accelerate - especially methods that are practical and directly address the needs of laboratories and society. The prevalence of counterfeit materials is a global concern and a risk to society across many markets. To combat this trend, in-situ analysis could become routine as instrumental methods employed for product quality and authenticity analysis advance, and as miniaturized analytical instrumentation improves and becomes more affordable in the next 10-20 years.

Novel direct MS analysis techniques, such as ambient MSn and flow injection MSn, have already started a revolution in quantitative screening methods. They allow analysis in seconds rather than minutes, representing an excellent tool for laboratories with high analytical demand. I believe that we will see many more methods implemented and published that use and improve these techniques in the next few years. In addition, kits that employ immunoassay technology are very common in clinical testing. This technology could continue to find applications in pesticide residue analysis, particularly in settings where a small number of analytes need to be measured. Various spectroscopic techniques (not just mass spectrometry) will likely play a key role in advancing in-situ analysis. For example, there are several commercially-available portable instruments based on ion mobility, infrared spectroscopy, raman spectroscopy and x-ray fluorescence. I expect that these instruments will get better over time and improve in-situ analysis.

The core analytical chemistry principles will likely remain in the analytical toolbox forever. Many techniques evolve, rather than disappear. Advances in liquid chromatography are an example of an evolutionary track; LC > HPLC > UPLC. It is likely that, as the "dilute-and-shoot" approach continues to expand, methods that involve hands-on sample preparation will be used less. Similarly, it is possible that several laboratories pursue implementation of ambient MS and flow injection MS to benefit from high throughput, which could decrease the use of chromatography-MS, particularly for screening purposes. That said, I believe that chromatography-MS combined with elaborate sample preparation will continue to allow the most selective and sensitive chemical analysis. Therefore, all the aforementioned techniques will play important roles for decades to come.


Challenges within the regulatory landscape

Some challenges in industry are different from those encountered in government and academic laboratories. Agrochemical industry R&D efforts have changed over the years with technology, as well as the regulatory landscape. For example, the number of analytes (active ingredient and metabolites) covered in pesticide residue methods in industry has increased significantly because of changes in regulation. Moreover, metabolites are often very difficult to analyze because of their physicochemical properties (polarity, stability, volatility). Consequently, the development of a multiresidue method in industry that covers about a dozen analytes (for example, one active ingredient with eleven metabolites) could require significantly greater effort than a pesticide screening method designed for more than 100 active ingredients. Additional challenges arise from the need to measure very low exposure levels, resulting in methods with detection limits significantly below the MRL. Therefore, novel techniques and methods that are broadly-applicable for both active ingredients and metabolites are needed. Another challenge is to maintain the simplicity of procedures to minimize resources utilized in laboratory operations - that's a challenge we all appear to share!

Of course, agrochemical industries must adequately address the scientific challenges encountered during the development of novel pesticides to comply with current regulations. In fact, industry stewardship practices and sustainability initiatives represent standards that are often more stringent than regulatory requirements. I believe the combination of stewardship, sustainability and regulatory compliance are absolute conditions for the existence and success of industry.

Industry relies on regulatory guidelines to direct long-term research efforts. The review of registration applications can have significant duration and, in the meantime, regulations can change or evolve. Regulations (and their amendments) impact all sectors at once: the agrochemical industry, farmers, consumer protection and commerce. Such a large impact emphasizes the importance of advanced communication of regulatory changes and phase-in periods for implementation. In other words, clarity in the regulatory landscape benefits society in general.

Unharmonized regulations represent a hurdle that, for the most part, has a negative impact by creating inefficiencies and confusion in the affected sectors. The good news is that regulatory harmonization, legislature and emerging topics of interest are under open discussion. International forums, such as EPRW, have been successful at bringing together scientist and experts from government, academia, industry and NGOs for debate and consideration of the various perspectives.

Regulatory compliance is intrinsic in industry laboratories dedicated to pesticide residue analysis and studies that are part of pesticide registration applications. But there are other research settings where novel analytical techniques can be explored, developed and implemented prior to broad acceptance, consideration or inclusion in regulatory guidelines. For example, novel methods for pesticide residue screening based on flow injection/mass spectrometry have been developed at DuPont. These methods have recently gained popularity; academic, government and industry research groups currently have active research programs running to further improve the technique. And so, while current analytical methods used in agrochemical product registration meet the regulatory criteria, novel and emerging techniques often contribute to the future regulation of analytical chemistry.



[ This article has been taken from the September 2014 Issue of »The Analytical Scientist«. You can read the original version and more articles with insights into analytical topics online at http://www.TheAnalyticalScientist.com (free registration required) ]

   
Record changed: 2016-03-20

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