Analysis of MCPD and glycidol in foods

3-Monochloro-1,2-propanediol (3-MCPD), 2-monochloro-1,3-propanediol (2-MCPD) and glycidol are among production-related contaminants in oil- and fat-containing foods. They are formed during the necessary refining process in the production of oils. 3-MCPD is suspected of damaging DNA and causing cancer. The European Food Safety Authority (EFSA) specifies 2 µg/kg body weight as the tolerable daily intake level for 3-MCPD. A harmful effect is also suspected for 2-MCPD. This has already been demonstrated for glycidol.

The analysis of these contaminants is becoming increasingly important due to their carcinogenicity. Different methods have been developed for the determination. The CHRONECT Workstation MCPD offers a fully automated solution for the four common methods.

Application DGF Fast & Clean - ISO 18363-1

Axel Semrau recommends this method, also known as DGF C-VI 18(10) or AOCS Cd 29c- 13, as the most powerful. It is therefore the basis for the first automation. Here, a version optimized in terms of sample throughput and robustness has been developed for automated operation: DGF Fast & Clean.

Sample preparation is fully automated on the CHRONECT Robotic autosampler. At the same time, an evaporation step was eliminated, which has been proven not to result in improved measurement accuracy.

A further step was integrated with the self-developed Clean-Technology and thus the method "DGF Fast & Clean" was created. An application is possible for both 3-MCPD and 2-MCPD as well as for the determination of the glycidol content. In this process, the analytes bound to fatty acids are first converted into their respective free form. The release from the fatty acid esters occurs by transesterification.

According to the DGF method, two approaches are required in sample preparation for the determination of the glycidol content. DGF Fast & Clean makes it possible to get a conclusion in a short time. The first result is available after only 48 minutes for the complete sample. The software CHRONOS and the autosampler CHRONECT Robotic allow a time nested processing of the samples. The next results are therefore available more quickly. Axel Semrau thus recommends this method as the most powerful method for the routine analysis of 3-MCPD, 2-MCPD and glycidol.

Advantages of DGF Fast & Clean

• Excellent robustness of the system
• Protection of the GC-MS
• Extension of maintenance intervals
• Excellent for routine analysis, incoming goods inspection or online analysis

Application 3-in-1 - ISO 18363-2

Normally, the analysis of 2-MCPD, 3-MCPD and glycidol is performed from fat or oil samples. If it is a compound food, the first step is to isolate the fat from the samples, which can be done by accelerated solvent extraction. To release the analytes, the fat must be transesterified. After conversion to the form required for measurement (derivatization), the analytes are analyzed by gas chromatography mass spectrometry.

This method, also referred to as AOCS Cd 29b-13, relies on a slow alkaline release of MCPD and glycidol from the ester derivatives. The procedure takes 16 h at -22 °C, stopping the cleavage with acidic sodium bromide solution and forming 3-MCPD as in other methods. By GC-MS, 2-MCPD and 3-MCPD are also quantified together in one step after derivatization with PBA.

The automated CHRONECT Workstation MCPD can be equipped with an additional evaporation unit, recently used for other methods such as AOCS Cd29a-13 and AOCS Cd29c-13, to allow measurements even on a single quadrupole mass spectrometer system with comparable LOQs.

The 3-in-1 module is therefore an excellent addition to your laboratory in a routine environment with reliable data. The method presented has the advantage that a sample can be analyzed for 2-MCPD, 3-MCPD and glycidol in a single run.

Application Unilever - ISO 18363-3

Ermacora and Hrncirik from Unilever originally published the AOCS Cd29a-13 method in 2013. Hence, the colloquial name "Unilever method".

In this method, the glycidyl esters are initially converted to 3-mono bromopropane-1,2-diol ester (3-MBPD-E) in the presence of bromide. Subsequently, all three ester-bound contaminants are cleaved from the fatty acids under acidic conditions and elevated temperature (40 °C). The free fatty acids are extracted in a subsequent step and the now free glycidol, 2- and 3-MCPD are derivatized with phenylboronic acid. The derivatives are extracted and injected into a GC-MS system. The corresponding ion traces for the three derivatives then provide a chromatogram. In addition, each analyte also shows a signal for the deuterated variant, which is added as an internal standard at the beginning.

The only manual step in sample preparation is the weighing of fat/oil samples. Subsequent preparation is fully automated, including injection into a GC-MS system. The analysis of 2-MCPD and 3-MCPD in one sample can be performed together in only one run. Multiple samples can be prepared simultaneously. The mandatory transesterification time of 16 hours can be used with the autosampler for other sample preparation options such as standard dilutions.

Application Zwagerman - Draft ISO 18363-4

In alkaline transesterification (room temperature), the resulting free 3-MCPD is very rapidly converted to glycidol, which leads to a false result without compensation.

In some methods, this conversion of glycidol is compensated differently. At -25 °C, it is kinetically controlled, or it is back-calculated by the addition of another halide (sodium bromide) in a second preparation. An alternative is the addition of a 13C3-labeled 3-MCPD ester standard, which allows the conversion of the 3-MCPD to be directly accounted for in a sample preparation run. Each sample thus requires only one sample preparation run.

This modified method was published in 2015 by Zwagerman et al. and represents an elegant and robust alternative for process control. It is currently in the standardization process and has also been automated with the CHRONECT Workstation MCPD.

Commissioning

The CHRONECT Workstations are pre-installed at Axel Semrau. Within the scope of an extensive Factory Acceptance Test (FAT), not only the correct technical function but also the analytical performance is checked. This test run is repeated after installation as part of a Site Acceptance Test (SAT) in the customer's laboratory. In this way, analytical accuracy is verified. The system is ready for use immediately after installation. The FAT/SAT concept ensures that the systems are integrated directly into the laboratory workflow and are used productively as quickly as possible.

Training and maintenance offers ensure permanent operational readiness and ensure that the necessary knowledge for operating the system is available even in the event of staff changes.

Further content and downloads

Each of the methods presented has advantages and disadvantages. Likewise, each laboratory has different requirements for the analysis of MCPD and glycidol in food. Here you can find further contents for each method.

Product information CHRONECT Workstation MCPD

Application note DGF Fast & Clean ISO 18363-1

Application Note 3-in-1 ISO 18363-2

Application Note Unilever ISO 18363-3

Application Note Zwagerman ISO 18363-4

We are also happy to assist you with the choice of method!