Jack Cochran | Authors


Vacuum Ultraviolet Spectroscopy: A New Tool for Gas Chromatography Analysis of Terpenes in Flavours and Fragrances

Terpenes contribute heavily to the senses of smell and taste and thus are integral to industries like herb and spice producers, essential oil manufacturers, cannabis growers and distributors, breweries, and distilleries, among countless others. Current terpene analysis is performed using gas chromatography–flame ionization detection (GC–FID) and GC–mass spectrometry (MS); however, baseline separation is needed for quantification because many terpenes of interest are isomers, which can lead to relatively long run times. Vacuum ultraviolet (VUV) spectroscopy can spectrally distinguish isomers and quantitatively deconvolve coeluting peaks, allowing for significant reduction in GC run time. This article outlines a method for the analysis of 21 terpenes in a variety of samples with a sub 9-min elution time.

Evaluation of Modified QuEChERS for Pesticide Analysis in Cannabis

While systems for growing, production and sale of cannabis and cannabis related products are well established, regulation and enforcement of quality and safety testing have lagged behind. However, state governments and private labs are focusing on product safety testing with special emphasis on pesticide analysis. This is partially the result of various product recalls, media attention and concern from patient advocacy groups. We evaluated a modified QuEChERS LC-MS/MS method for analysis of multiresidue pesticides. The AOAC QuEChERS method was used for a reduced 1.5 g amount of plant material and processed with a universal dSPE formulation. LC-MS/MS analysis used constant polarity switching ESI and monitored at least two transitions per analyte. Matrix-matched calibration was used for quantitation and both method and instrument internal standards were used. Analyte recovery validation was performed according to FDA guidelines by testing three matrices at three fortification levels in triplicate for over 200 pesticides. For the large majority of pesticides, in all three matrices and at all three fortification levels, recovery was between 70-120%.

Split Injection GC: Increasing Response Factors for Compounds Prone to Inlet Liner Adsorption by Using Shoot-and-Dilute GC

“Practical GC” provides readers with practical advice and new experimental evidence for how to get the best results from their gas chromatography (GC) systems. The next instalment looks at the potential for reducing inlet adsorption of active compounds through the use of split injection GC.

Semivolatiles Analysis Using Split Injection

Analyzing a broad range of semivolatile environmental pollutants at low levels requires a sensitive detector as well as an inert sample pathway. While semivolatiles analysis by methods such as EPA 8270 and EPA 625 typically does not require reporting sub nanogram-on-column concentrations, the latest generation of sensitive mass spectrometers and inert GC columns and inlet liners allow analysts to take advantage of the benefits of split injection while maintaining standard method reporting limits.

Split Injection GC: Setting the Split Ratio in Shoot-and-Dilute GC

Jack Cochran’s new column “Practical GC” provides readers with practical advice and new experimental evidence for how to get the best results from their gas chromatography (GC) systems. This instalment looks at understanding and using split ratio for “shoot and dilute” GC.