Archive for the ‘QuEChERS’ Category

EPRW: European Pesticides Residue Workshop in Sunny Cyprus

                                    Just wanted to let everyone know that we have published our presentations we presented at EPRW (European Pesticide Residue Workshop) last month in Limassol, Cyprus. It was a great meeting in a beautiful location. It was a pleasure to […]

Extraction Method for Cannabinoid Analysis in Edibles: Too Much of a Good Thing

After a long blog hiatus, I’d like to address one of the most frequently-asked questions we get from cannabis labs: “how do we quantitatively extract cannabinoids from edible matrices?”. With the huge number of matrices out there, limited peer-reviewed data, and lack of sufficiently concentrated reference standards for spiking, it’s no wonder that after several […]

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 […]

Split Injection Makes for Easier Polar Solvent GC Work versus Splitless Injection

As anyone who’s doing QuEChERS knows, analyzing acetonitrile extracts on nonpolar GC columns (like Rxi-5ms, e.g.) using splitless injection can be problematic because of the classic solvent – stationary phase mismatch.  To avoid split peaks we usually have an initial GC oven temperature slightly above the 82°C boiling point of acetonitrile (MeCN), but this causes tailing […]

7th International Symposium on Recent Advances in Food Analysis (RAFA)

The 7th International Symposium on Recent Advances in Food Analysis, better known in short as RAFA, starts this week in Prague, The Czech Republic.  This is my tenth anniversary for this biennial meeting, where the organizer, Jana Hajšlová, invited me to give the lecture, Using the QuEChERS Sample Preparation Method and GCxGC-TOFMS to Determine Pesticides […]

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 […]

You want them, I got them…a lot of them: pesticides GC-MS/MS transitions

I can tell you that determining transitions (SRMs) for GC-MS/MS can be quite challenging with so many precursor ions to evaluate. I spent a considerable amount of time optimizing transitions for our GC Multiresidue Pesticide Kit which has 203 compounds. That is a lot of transitions to evaluate! I also tested my chromatographic method for […]

LVI-SV with MMI Inlet Using a Restek Premium 2.0 mm Single Taper Liner w/ Wool

Agilent’s Multimode (MMI) Inlet can be used as a PTV (programmable temperature vaporization) type inlet for large volume injections, with the advantage of using standard sized split/splitless liners.  This technique requires careful optimization of a number of parameters, which starts by choosing a proper inlet liner.  I recommend trying a Restek Premium 2.0 mm Single […]

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 […]