Archive for the ‘Pesticides’ Category

Modifying QuEChERS for complicated matrices- Dry Samples

Before getting in to this discussion, I recommend reading my previous blog post first regarding classical applications for methods based on Quechers. https://blog.restek.com/quechers-dspe-selection-which-one-is-best/ QuEChERS methods were originally written to analyze pesticides in fruit and vegetable matrices, most of which have high water content and low fat content. More recently, the technique has been used for […]

Tips on the analysis of pesticides and mycotoxins in cannabis products: Matrix matters! (Part II)

In part I of this blog series, we learned about matrix effects, how to assess them, and how to address them (you can check the blog here). One of the main conclusions of part I was the importance of using matrix matched calibration as the means to account for possible ionization effects in LC-MS/MS, and […]

Pesticides are like Siblings, They Don’t Always Get Along part 2 – now with the GC mix!

Last year my colleague Landon publish his blog about pesticide multiresidue LC mix stability in a celery matrix and in a solvent. Today, I’d like to show you what happens when you do this with the GC multiresidue pesticide kit. On day 0, I prepared stock solutions from all 9 ampules of the GC multiresidue […]

Quechers dSPE selection- which one is best?

Method development for Quechers sample cleanup can be a complicated task. Not only does the analyst need to make sure their analytes of interest can be recovered, but the matrix interferences must be removed enough to make the quantitation possible and reliable. It makes sense that selecting the best dSPE products is highly dependent on […]

Tips on the analysis of pesticides and mycotoxins in cannabis products: Matrix matters! (Part I)

The growing variety of cannabis products that are currently available in the market speaks volumes about the creativity of entrepreneurs within the industry. Vapes, lotions, balms, cookies, hard candy, gummies, infused drinks, chocolate, fudge, soaps, and tinctures are only a handful of the product types that are currently being commercialized in this ever-growing market. Such […]

Analyzing avocado: How to deal with lack of water and keep the fats out

Avocados are a popular produce item. In fact, the consumption of avocados rose by 450% since 2000! The good news – avocados are ranked number 1 on the clean 15 list, meaning they have the least amount of pesticide residues. With so many avocados on the market, the testing is as important as ever, which […]

GC Inlet Liner Selection, Part III: Inertness

The inlet liner is the first surface analytes will interact with after introduction into a GC.  It is critical that liners are deactivated, as a number of adverse interactions can occur between analytes and the glass surface.  Deactivations typically involve some type of silanization of the surface to cover active sites inherent in glass, such […]

Analyzing orange: peel and pulp separately or as whole?

Up to this point, I’ve focused on the optimization of QuEChERS salts and dSPE cleanup with fairly homogenous matrices. So, what about oranges? Should I peel them and analyze only the pulp? After all, that is the edible part. The peel is used as well – pressed into essential oils or scraped into zest. Besides, […]

Got Fast Columns? Clean Up Your 8081 Samples Using CarboPrep Plus as a Substitute for Florisil

My colleague Linx Waclaski blogged about a tale of two columns that started with the introduction of a pair of stationary phases specifically tuned for the resolution of the 20 legacy pesticides found in US EPA Method 8081(1). The story examined the gains in speed over the years as measured by the last eluting compound […]

A Tale of Two Columns (CLPesticides and CLPesticides2)—Part IV: Fast 8081 Method Using GC Accelerator Kit

The moment has finally come to see how we can use the GC Accelerator to get the most horsepower for your 8081 analysis.  If you’ve been following this blog series, you will remember that in Part II, I talked about ways to make your runs faster.  I also showed you our previous fast “7 minute” […]