The setup of “DGF Fast and Clean” is represented schematically in figure 3. For the automation of the sample preparation Axel Semrau® chooses a 160 cm PAL3 DHR by CTC Analytics. This autosampler offers enough space for all required modules and can easy be adapted to other methods or applications. The dilutor is equipped with three solvents (n-hexane, extracting agent and iso-octane).
The PAL3 autosampler has been mounted onto a GC MS MS. This allows the immediate injection of the sample after preparation. Alternatively, the installation is also possible with instruments of other manufacturers or based on pre-existent GC-MS devices.
To avoid condensation of the derivatization reagent phenylboronic acid on the analytical column or ion source of the triple quadrupole, the GC system is provided with a backflush. This contributes to an extended lifetime of the triple quadrupole after at least 200 injections and delivers robust data. The entire control of the system is conducted by the user-friendly software CHRONOS, making even complex procedures easy to handle. The CHRONECT solutions by Axel Semrau® are preinstalled in application laboratories and tested (Factory Acceptance Test). Then, the systems are delivered ready-to-use to the customer and tested at the customer’s lab one more time (Site Acceptance Test). Thus, the quickest possible continuation of the routine measurement is assured.
Due to CHRONECT Robotic, CHRONOS in combination with PAL3 autosamplers, individual operations can be performed closely interlaced. Applying the “DGF Fast and Clean” method, results are available after 45 minutes only, as shown in figure 4. Traditional methods require up to 18 h reaction time. Interlaced processes enable the measurement of 36 samples in 24 hours. As a consequence, the new system provides highest precision in combination with a significant time saving. The obtained result always complies with the conventional DGF method.
The modular PAL3 system allows for the automation of other methods and therefore is perfectly suited for the everyday lab routine.
For example, the 3-in-1 method by SGS (AOCS Cd 29b-13) may partially be automated. Still, due to the individual steps of the method, a short manual interaction is required. For the Unilever method (AOCS Cd 29a-13) a centrifuge can be added and integrated making this method as well automatable as the Zwagerman-Overman method. Equally, the earlier Weisshaar method has already been implemented.
Measuring parameters and results
A closer glance at the “DGF Fast and Clean”: The components 3-MCPD and 2-MPCD and corresponding deuterated variants were detected using the triple quadrupole technique. Thus, for each compound one ion was selected for qualification and one for quantification.
The respective collision energies for the fragmentation of the parent ions after the first quadrupole were determined experimentally.
Important parameters for the particular components of the GC-MS device are shown in table 1.
For validation of the application, DGF “classical” was validated first. Samples are prepared exactly according to the DGF guidelines and then are injected. For validation, rac-1,2-Bis-palmitoyl-3- chloropropanediol und rac-1,3-Distearoyl-2-chloropropanediol were used. Defined amounts of the two compounds were added to a native olive oil and subsequently prepared using the CHRONECT Robotic system.