Pesticides Are Like Siblings, They Don’t Always Get Along, Part 3 – Opened Ampul Stability

ByAudrey Crater

Two of my RESTEK colleagues, Landon Wiest and Jana Hepner, have posted parts one Pesticides are like Siblings – some get along well and some don’t – No. . .Really? and two Pesticides are like Siblings, They Don’t Always Get Along part 2 – now with the GC mix! on this topic showing what happens to the 200+ pesticides in our LC and GC multiresidue CRM kits when the mixes are all combined together into a single mixture then used to detect pesticides in celery matrix. Both confirmed with their study results that once pesticides ampules are mixed together and stored for a number of days some pesticides degraded immediately while others degraded over a longer timeframe. 

High-Quality Analysis of Pesticides in Cannabis Using QuEChERS, Cartridge SPE Cleanup, and GCxGC-TOFMS

ByAudrey Crater

As medical marijuana is more frequently prescribed, patient safety must be ensured. Pesticide residue testing is an important part of assuring safe product is dispensed, but analysis can be extremely challenging due to matrix complexity. The use of QuEChERS, cartridge SPE cleanup, and GCxGC-TOFMS as presented here, produces high-quality quantitative data for this difficult analysis.

Comparing Pesticide Residues in Amish and Commercially Grown Strawberries and Spinach Using QuEChERS, Various dSPE Sorbents, and GC-TOFMS

ByAudrey Crater

QuEChERS extraction, dSPE cleanup, and GC-TOFMS analysis were used to assess pesticide residue levels in strawberry and spinach from both commercial and Amish growers. Various dSPE sorbent products were compared to determine which were most effective.

Analytical Method for Polycyclic Aromatic Hydrocarbons (PAHs) in Yerba Mate Tea Using Modified QuEChERS, Solid Phase Extraction and GC-TOFMS and GC-MS/MS

Analytical Method for Polycyclic Aromatic Hydrocarbons (PAHs) in Yerba Mate Tea Using Modified QuEChERS, Solid Phase Extraction and GC-TOFMS and GC-MS/MS

ByAudrey Crater

This application note describes the development of an analytical method for PAHs in tea that allows analysts to more quickly and accurately characterize target PAHs. Sample preparation is based on a modified QuEChERS extraction and solid phase extraction sample cleanup. Both GC-TOFMS and GC-MS/MS techniques were used and analyses were optimized for resolution of isobaric compounds, as well as for maintaining a reasonable analysis time.

Evaluation of Dispersive and Cartridge Solid Phase Extraction (SPE) Cleanups for Multiresidue Pesticides in QuEChERS Extracts of Finished Tobacco Using GCxGC-TOFMS

ByAudrey Crater

We compared the efficacy of dSPE and cSPE cleanup methods for multiresidue pesticide analysis of QuEChERS extracts of finished tobacco products using GCxGC-TOFMS. Cleanup with dSPE tubes containing 7.5 mg of GCB and 25 mg of PSA produced better results than other methods, with average recoveries of 92% and 91% for 500 ppb and 50 ppb fortifications respectively.

Robust 9-Minute GC Analysis of Cholesterol

ByAudrey Crater

Conditions are established for analyzing both derivatized and underivatized cholesterol on a highly inert Rxi-5ms column. Methods described include both an isothermal analysis for use when interferences are minimal, but sample throughput is critical, and a temperature program for use when separation of analytes from contaminants or interfering compounds is the primary concern. Results for both derivatized and underivatized samples were highly reproducible.

Characterizing All 136 Tetra- to Octachlorinated Dioxins and Furans

ByAudrey Crater

The Rtx-Dioxin2 column has a unique selectivity for dioxins and furans, including specificity for 2,3,7,8-TCDD and 2,3,7,8-TCDF. Here we characterize all 136 tetra- through octachlorine dioxins and furans and define all possible coelutions. While commonly used cyanopropyl columns are limited by a low maximum operating temperature of 240°C, the Rtx-Dioxin2 column is stable up to 340°C, extending column lifetime and improving the analyses of dioxins and furans.

Fast, Simple Sample Cleanup

ByAudrey Crater

Quick, Easy, Cheap, Effective, Rugged, and Safe, the QuEChERS (catchers) method for extracting pesticides from food is based on USDA research and employs a novel dispersive solid phase extraction cleanup (dSPE). QuEChERS methods are convenient, rugged methods that simplify extract cleanup, reduce material costs, and improve sample throughput. Here we demonstrate the effectiveness of QuEChERS sample cleanup using a multiresidue analysis of pesticides on strawberries.

Large Volume Splitless Injection Using an Unmodified Split/Splitless Inlet and GC-TOFMS for Pesticides and Brominated Flame Retardants

ByAudrey Crater

Concurrent solvent recondensation large volume splitless injection (CSR-LVSI) GC/MS is used here for analyzing pesticides and brominated flame retardants in drinking water based on EPA Method 527. CSR-LVSI allows a time-consuming sample extract concentration step to be eliminated, but can also be used with extract concentration for lower detection limits.

High Sensitivity Melamine GC/MS Analysis of Cat Food

ByAudrey Crater

Melamine contamination was implicated in a large pet food recall that occurred in 2007 when animals died after eating contaminated pet food. Here, a modified GC/MS method, based on an FDA method, was used to analyze for melamine & related compounds cyanuric acid, ammelide, and ammeline in dry cat food. Analytes were easily identified by retention time matching and mass spectra.