Posts Tagged ‘QuEChERS’

Modifying QuEChERS for complicated matrices- High Fat Samples

This post is part of a series on QuEChERS. Here are links to the previous two posts, in case you may wish to catch up before reading this one: QuEChERS dSPE selection-which one is best? Modifying QuECHERS for complicated matrices- Dry Samples (See Jana’s post here for further details on dry samples: QuECHERS approach optimization […]

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 […]

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 […]

Pesticide analysis for cannabis flower: method and data overview

Pesticides in cannabis has been a hot topic lately and we have been getting many requests for help with this analysis. We did work on pesticide residue testing in cannabis about 6 years ago. At that time, we were limited to testing our methods with a small amount of seized material. Recently, we have been […]

Need Help with QuEChERS: #AskRestek Twitter Q&A session

Just wanted to let everyone know we will be hosting a #AskRestek Twitter Q&A session about QuEChERS next week at 3:00 p.m. EST (12:00 noon PST) on Tuesday, May 3. QuEChERS is a great approach for sample preparation with lots of benefits. It is also very flexible which is nice but that can also make […]

Difficult QuEChERS extracts: Removing fatty acid interferences

Using the QuEChERS extraction and cleanup method for high fat commodities such as, nuts, dairy, fish, and avocado can be difficult to analyze for pesticide residues.  Using the dispersive solid phase (dSPE) cleanup sometimes is just not enough to adequately remove the fatty acid co-extractives. Check out this technical article on how to quickly yet […]

The Most Useful Pesticide Standard Ever…monitoring GC inlet “dirtiness”

I have spent most of my time over the past several years testing pesticides and there is one standard that I simply can’t live without…QuEChERS Performance Standards Kit. It is based on a really interesting article* on analyte protectants with a few compounds added. The standard has 40 compounds housed in three vials for long […]

Great Internal Standards for Pesticide Residues…SRMs too!

  In just about all of my pesticide residue work, I use a convenient multicomponent internal standard mix that contains several PCBs as well as popular internal standard compound triphenylphosphate. The mix contains the six compounds in the chromatogram below. I have been working on a method for our GC Multiresidue Pesticides Kit which has […]

QuEChERS – Where to start?

Enjoy the tip!* I am often asked for QuEChERS product recommendations. Usually the request is something like, “I need to test pesticides in _____” and that blank can be just about anything…sometimes not even food. Unless it is something I have tested before, I usually take a quick look online to determine the approximate composition […]

Which GC instrument should I use for the analysis of pesticides in herbal tea? GC-MS/MS or GCxGC-TOFMS?

You may remember a while ago I posted a blog about the analysis of herbal tea using QuEChERS and GCxGC-TOFMS.   The LECO Pegasus GCxGC-TOFMS is a great instrument for analyzing complex samples because of the comprehensive chromatographic separation achieved (two columns with different selectivities).  The GCxGC-TOFMS also excels at non-target screening of compounds.  Lucky for […]