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GC Analysis – Part VIII. Calibrated Compound Quantification

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GC Analysis – Part VIII. Calibrated Compound Quantification

17 September 2015

Alexis St-Gelais, M. Sc., chimiste – Popularization Although it constitutes a large part of our activities at PhytoChemia, essential oils analyses are in fact a special case for chemists. Indeed, it is one of the only cases (along with hydrosols, fatty acids methyl esters and a handful of other applications) where the approximation “concentration ≈ % […]

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GC Analysis – Part VII. Hydrosol Analysis

15 March 2015

Alexis St-Gelais, M. Sc., chimiste – Popularization We have previously seen a worked example of essential oil analysis. Hydrosols can be analysed in about just the same way as essential oils. Yet, there is one huge difference between a pure essential oil and an hydrosol: the latter is always a solution. This implies some specific […]

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GC Analysis – Part VI. Applied Example of Analysis with Retention Indices

8 September 2014

Alexis St-Gelais – Popularization I wrote some time ago about retention indices in GC-FID and the advantages of using two columns to analyze an essential oil. Since this is a central aspect of the work we do using GC, I wished to detail a real-case analysis, allowing you to understand more clearly our methodology. Throughout […]

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GC Analysis – Part V. FID or MS for Essential Oils?

2 September 2014

Alexis St-Gelais – Popularization [Minor addenda to the original text were made on March 23, 2019, and are noted in green] An important task of analytical chemistry is to select the detector that best suits the purpose of an analysis. Each detector has indeed its pros and cons. In the area of essential oils, FID and […]

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GC Analysis – Part IV. Retention Indices

25 August 2014

Alexis St-Gelais – Popularization I mentioned in the first post of this series on GC analyzes that PhytoChemia resorted simultaneously to two capillary columns to analyze essential oils, one polar (Solgel-Wax) and one non-polar (DB-5). The rationale behind this technique will reveal some of the art of interpreting essential oils profiles.  We have seen that […]

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GC Analysis – Part III. Mass Spectrometry Detection (MS)

18 August 2014

Alexis St-Gelais – Popularization My last post gave some details about a detection method commonly used in GC, the FID. Another detector that is widely used for the analysis of volatile compounds, including at PhytoChemia, is the mass spectrometer (MS). Unlike the FID, the MS is a complex detector. Typically, in GC-MS (although other modes […]

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GC Analysis – Part II. The Flame Ionization Detector (FID)

11 August 2014

Alexis St-Gelais – Popularization The first part of this series dealt with the principles of separation of volatile molecules upon analysis by GC. After their separation, the analyst has yet to be able to detect molecules as they leave the capillary column, either to identify or quantify them. At PhytoChemia, we mainly use two types […]

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GC Analysis – Part I. Separation Principles

30 June 2014

Alexis St-Gelais – Popularization I have explained in a previous post the main theoretical principles of chromatography. Today, I will detail one of its practical applications, widely used by PhytoChemia: gas chromatography (GC). It lends itself to the analysis of volatile molecules – that is to say molecules capable of passing to gas phase at […]

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Do It Faster, Makes Us Stronger – Fast GC

11 May 2017

Benoit Roger, Ph. D., & Alexis St-Gelais, M. Sc., chimiste We have read many times on various oils-oriented Facebook groups indications that gas chromatographic columns should be as long as possible to achieve proper separation. Similarly, it is often stated that short analysis runs negatively impact the quality of data obtained. And under the most […]

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Quality Control 101, Part II. How to read a GC report

15 October 2015

Hubert Marceau, chimiste – Popularization As more and more consumers are aware of the existence of essential oil adulteration, distributors are starting to offer GC reports with their oils. We believe that this is a good step for multiple reasons. It shows that the company has made its best efforts to offer to its customers […]

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