Determination of Cereulide in Infant Formula and Rice Cereal by SPE-UHPLC-MS

Contamination by microbial toxins is a key risk in food safety management that requires prevention and control. Among these, cereulide is an emetic toxin widely found in grains and dairy products. It is a potent cytotoxin which causes nausea and vomiting, and is produced by some strains of Bacillus cereus, Bacillus megaterium and related species^[1].

Infant formula and rice cereal, as essential foods for infants and the general public, respectively, have complex matrices and are subject to significant interference from impurities, which places extremely high demands on the accuracy, stability, and resistance to interference of toxin testing.

To address the particular challenge of determining cereulide in infant formula and rice cereal, Welch Materials has developed a specific method based on T/WSJD 57-2024. It is based on proven chromatographic separation and sample preparation techniques, using Ultisil DLC UHPLC XB-C18 column paired with mass spectrometry and Welchrom HLB solid-phase extraction (SPE) cartridge. Verified through a comprehensive set of experiments, the method delivers stable performance and accurate data, and is fully suited to the routine, high-throughput testing needs of laboratories, providing robust support for food quality and safety screening.

Sample Preparation:

• Sample Extraction: Weigh 1 g of homogenized sample into a 15 mL centrifuge tube. Add 20 µL of the internal standard working solution (0.1 mg/L). Stand still for 30 mins, then add exactly 5.0 mL acetonitrile, vortex for 30 seconds, sonicate for 30 mins, and centrifuge at 4 °C, 12000 r/min for 10 mins. Transfer all the supernatant into a 15 mL centrifuge tube and add 5.0 mL water. Vortex for 30 seconds, then proceed to cleanup.
• Cleanup: Welchrom HLB cartridge, 200 mg/6 mL
  • Activation: 3.0 mL methanol followed by 3.0 mL pure water.
  • Loading: Load the entire extract.
  • Rinse: 3.0 mL pure water.
  • Elution and Reconstitution: Elute by 5.0 mL methanol. Collect all eluant and evaporate to near dryness by nitrogen. Reconstitute the residue by 1.0 mL initial mobile phase (i.e A:B=80:20), and filter through a microporous membrane.

Using Welch Ultisil DLC UHPLC XB-C18 (2.1×50 mm, 1.8 µm) column and Welchrom HLB (200 mg/6 mL) SPE cartridge, cereulide exhibited excellent peak shapes, and the rice cereal and infant formula samples had their recovery rates meet the criteria of the method standard.

The DLC (diamond-like carbon) coated column, compared to conventional stainless steel columns, demonstrated better response values for low-concentration samples in this assay, allowing accurate determination of samples at lower concentrations.