vial_carouselThe characterization of the volatile fraction of a liquid or solid sample is definitely a field of gas chromatography coupled to headspace sampling technique. Static or dynamic or through SPME enrichment, the headspace sampling offers a convenient solvent-less extraction approach, requiring almost no sample preparation, for the analysis of volatile compounds in a sample. Particularly suitable to be fully automated, the headspace sampling is very popular in testing laboratories doing routine volatiles determination.

The basic principle underlying all instrumentation for headspace-gas chromatography is that an aliquot of volatile compounds from the vapor phase above a liquid or solid sample in a sealed vial must be reproducibly and effectively transferred to the inlet of a gas chromatograph. There are several means for accomplishing this, including gas-tight syringe, pressure-balanced time-base, valve-and-loop and collection on a sorbent. The most important challenges are to ensure that the sample composition that reaches the gas chromatograph is truly representative of the composition of the headspace vapor in the vial and that the headspace vapor is representative of the composition of the original sample1.

Short and fully inert sample-path, precise and accurate pressure control during transfer, and efficient heating of the entire sample path are the key points to assure high data quality, robustness and system reliability. The valve and loop-based Thermo Scientific™ TriPlus™ 500 Headspace autosampler, with its innovative direct column connection design, offers all those benefits, including a superior recovery over a wide volatility range, compared to the standard static headspace autosamplers on the market.

Capable to operate up to 300°C with extended recovery of > 60% for C40, the TriPlus 500 HS autosampler can be successfully used to explore high-temperature applications.

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This is exactly what Dr. Matthew Noestheden from Supra RnD realized when using on a daily basis his TriPlus 500 HS coupled to the ISQ™ 7000 GCMS. Matt’s idea was to use the headspace autosampler as a surrogate vaporization environment to study the decomposition processes in e-cigarettes, working at the temperatures used in vaporizers, in order to characterize possible health risks associated to a given ingredient. The recent set of severe illnesses and 47 deaths appeared as a cluster after a few years of widespread use of vaporizers. Many of these adverse health effects have been associated with vitamin E acetate (α-tocopheryl acetate), a product that is not toxic by ingestion and never been identified as a problematic ingredient2. Read more on Matt’s study on Vitamin E degradation by high-temperature HS-GC-MS.

Extending the applicability of the static headspace sampling to high temperatures operation opens up new testing capabilities covering less-volatile compounds. We have seen that the TriPlus 500 HS working at high temperature has been used to investigate the possible use of static headspace for the detection of volatile and semivolatile residual organics from oil contamination in aluminum foils during manufacturing, a test required to ensure the delivery of high-quality and safe products.  Several industries make use of these materials including the automotive, HVAC, transformer and food packaging industries. For this application the TriPlus 500 headspace autosampler was used at temperatures between 150-300°C, permitting the analysis of less volatile compounds. Important to say that working at a high temperature requires also the use of suitable high-temperature consumables. In particular, the caps and septa for the headspace vials need to be suitable for high-temperature operation, assuring the correct tightness and less bleeding, like the 20 mm magnetic tin plate crimp cap, 20 mm red silicone/natural PTFE high temperature, P/N 20-MCB-ST3HT (highly recommended if going up to 300°C, to be used with an automatic crimper).

The HT operation along with the direct column connection design of the TriPlus 500 HS, allowed to recover > 800 different hydrocarbons within a lubricant oil sample, including several fatty acid esters. The whole analysis could be carried out in automated, completely solvent-free fashion,  making it a simple and fast testing approach which can be easily implemented in a quality control lab to monitor the manufacturing process of aluminum foils.

Now you know a bit more on the high-temperature headspace capability of the TriPlus 500 HS, but should you still have additional questions, discover more features and benefits on www.thermoscientific.com/triplus500

  1. Headspace-Gas Chromatography, Michael J. Sithersingh, Nicholas H. Snow, in Gas Chromatography, 2012
  2. Blundell, M. S.; Dargan, P. I.; Wood, D. M. The dark cloud of recreational drugs and vaping. QJM 2018, 111, 145–148.