cooking-oilMonochloropropanediol esters (MCPDe) and glycidyl esters (GE) are the central point of attention of the food industry. Those compounds are unwanted by-products of oil refinery and predominately occur in palm oil. Due to the genotoxic and carcinogenic properties of those compounds, great care should be taken in processing the oils. Nonetheless, any oil can contain MCPDe and GE when it is not processed with the utmost care. Therefore, the European Commission amended EU Regulation to include maximum levels for GE in all edible oils that are to be placed on the European market, including reduced limits for infant formulae and their corresponding vegetable oil ingredients.

Generally, MCPDe and GE occur as esters in the oil matrix. But they require transesterification and derivatization prior to analysis in order to report total MCPD and GE contents. Sample preparation can account for a significant amount of time spent in an analytical workflow. The key to increased productivity and reproducibility is sample prep automation. A complete automated method for analysis of MCPD‐ and glycidyl esters is described from Zwagerman and Overman (2019) and applicable for the robotic Thermo Scientific TriPlus RSH autosampler as a completely automated solution.

Follow this link to learn more about automated sample prep workflows.

The glass quality is a key factor for success in automated derivatization. This is the most critical step in the workflow since at this point of process analytes polarity plays a central role. In order to reach the necessary detection limits, it is essential to ensure that analytes do not remain on the glass walls during derivatization. The best solution is a  first hydrolytic glass with a quality of 29% free silanol groups, better known as Chromacol GOLD ultra-inert vials.

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The robotic autosampler TriPlus RSH equipped with a modified heated tray was used for automated sample preparation. The workflow was developed and programmed by SampleQ. All samples were analyzed using a Thermo Scientific Trace 1300 gas chromatograph with an Instant Connect split/splitless injector capable of performing backflush. Subsequent detection of analytes was performed with a Thermo Scientific TSQ 9000 Triple Quadrupole MS/MS.

The automated workflow contains the complete sample preparation. In addition, all calibrations, QC sample, and blanc oil are automatically prepared in the workflow. Data review was performed using Thermo Scientific Chromeleon CDS software. Likewise, control of blanc, QC sample, calculations, as well all classic controls of GC-MS such as retention time, IS recovery and ion ratios were monitored automatically. For compound separation, a Thermo Scientific TG5silMS (30m x 0.23mm ID x 0.25µm) was used, connected to a 2 m precolumn of 0.53mm ID. For additional information on the complete workflow take a look at this application poster.

The approach for automated MCPD and GE analysis enables the following:

  • Limiting the manual labor to weighing in the sample
  • Analyzing a full scope of the MCPDe and GE in one single injection
  • Short reaction time without evaporation
  • Short analysis time
  • GE, 2-MCPDe and 3-MCPDe are measured in the same run
  • High productivity – 40 real samples per day from prep-to-rep to 80 samples per 24h in off-line mode
  • Automated calibration curves and addition of internal standards and automated QC control
  • Automated calculation, data evaluation and LIMS export
  • Complete sequencing, data reviewing and reporting in one single software.

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