Published Jack Cochran on October 23, 2017
As mentioned in my previous blog post, ASTM D8071-17: Standard Test Method for Determination of Hydrocarbon Group Types and Select Hydrocarbon and Oxygenate Compounds in Automotive Spark-Ignition Engine Fuel Using Gas Chromatography with Vacuum Ultraviolet Absorption Spectroscopy Detection (GC-VUV) uses an initial oven temperature start of 35°C, which can be hard to achieve for labs where room temperatures are warm. Hopefully in that post I convinced you that the potential exists for easing the initial oven temperature up from 35 to 40°C to shorten the GC oven cool-down time by comparing gasoline numbers generated from both oven start temperatures. As my colleagues have pointed out though, I should have started with evidence from the analyses of the System Validation Mixture for D8071, a quantitative blend of numerous gasoline components. Of course, anytime I do PIONA GC analysis, I start by verifying that the System Validation Mixture, affectionately called “VUV1” in our laboratory, meets our specification.
Figure 1 is a chromatogram of “VUV1”, the System Validation Mixture, with some key components labeled.
Figure 1. GC-VUV chromatogram of the ASTM D8071 System Validation Mixture with some of the key components labeled.
Figures 2 and 3 demonstrate that PIONA results (Paraffins, Isoparaffins, Olefins, Naphthenes, Aromatics) for the System Validation Mixture analyzed with GC oven starts of 35°C and 40°C compare quite favorably.
Figure 2. GC-VUV PIONA System Validation Mixture results for 35° GC oven temperature start.
Figure 3. GC-VUV PIONA System Validation Mixture results for 40° GC oven temperature start.
The same can be said for individual compound results (Figure 4). All results “Pass” our current specifications.
Figure 4. GC-VUV PIONA System Validation Mixture select hydrocarbon results for GC oven temperature starts of 35 and 40°C.
Author
Jack Cochran
Jack has spent 30 years in laboratories performing GC method development related to environmental, food safety, metabolomics, forensics, petroleum, and cannabis applications. He is a noted expert in sample preparation, GC-MS, and GC×GC, and is frequently an invited speaker at scientific conferences. Jack oversees the Applications Team at VUV Analytics as well as develop new applications for the award-winning VGA-100, VGA-101, and SVGA-100 gas chromatography and streaming gas detectors. Jack previously served as Director of New Business and Technology at Restek where he led the GC Applications Team and contributed significantly to new product development.
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