Archive for 2020

The new U.S. EPA Method TO-15A blog series – Part 2: Use air when analyzing air!

Last time, we left you with a teaser, how to take your canister blanks from the following red trace down to the blue trace: Before we get to that, let us back up to 2015, where both Wayne Whipple (retired US EPA) and I coincidentally presented on canister cleaning and canister blank levels at the […]

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 […]

Terpene Analysis Approaches – Part IV

We are back at it with another blog about terpene analysis! If you did not catch my previous post, be sure check it out here before moving on. Last time, I finished up by discussing how we would move away from analyzing terpenes in standards and dive into in-matrix analysis. Well…I lied. I’m sorry, but […]

ProEZGC Chromatogram Modeler – there is much more to the program than just the Welcome Screen

When you log into the ProEZGC Chromatogram Modeler software, you will see the screen below, which is what I refer to as the Welcome Screen. This is the starting point for all, and unfortunately all some customers will think there is to the ProEZGC software.   For those of you who have used ProEZGC, you […]

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 […]

Optimizing Splitless Injections: Inlet Temperature

One of the key parameters that requires optimization for splitless injections is inlet temperature.  With liquid injections, the analyst is relying on the volatilization of the sample upon introduction into the inlet.  The analytes can then be efficiently transferred to the column in a vapor state, where they are refocused, prior to beginning the chromatographic […]

Time to make lemonade with your Agilent 1100 – HPLC routine maintenance

They say when life hands you lemons, make lemonade. In this case, the COVID-19 pandemic has handed us all more downtime, so let’s talk about one aspect of a testing lab that tends to get overlooked or given less priority than other daily tasks: routine maintenance. The combination of downtime cannabis labs are experiencing due […]

Spring Cleaning Your GC System

Spring has sprung and now is a good time to give your GC system a thorough going over.  There is routine maintenance that we should perform all the time to keep the GC in tip-top condition like changing the liner, o-ring, septum, using your electronic leak detector and column trimming; but there is also periodic […]

Analysis of noble and permanent gases on adsorbent columns

Predicting selectivity characteristics of adsorbent columns is often a wild guess. Yes, we know argon will have less retention than krypton, but how well do adsorbent columns separate noble gases from permanent gases? Can neon and hydrogen be resolved using a porous polymer column or do we have to use more retentive columns, like Molecular […]

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 […]