A rapid screening method for the determination of melamine and cyanuric acid in milk products is developed using Agilent 7890A/5975C GC/MSD along with Agilent J&W HP-5ms GC columns. With the backflushing by capillary flow technologies, this method eliminates the time consumption for column bakeout after elution of target compounds, so as to significantly shorten the GC run time from more than 70 minutes to 14.5 minutes. Good linearity was obtained within the range of 10 to 200 µg/g, with correlation coefficients greater than 0.9996. The recoveries of both target compounds are greater than 95%.
The document presents a modified U.S. FDA method developed by Agilent Technologies to analyze melamine and cyanuric acid in milk products. The primary challenge addressed is the presence of nonvolatile matrix components like protein and fat, which typically require lengthy high-temperature baking to clean the column after analysis.
To solve this, the authors utilize an Agilent 7890A gas chromatograph equipped with a split/splitless inlet and an Agilent 5975C GC/MSD. The method employs Capillary Flow Technology with a three-way splitter device and auxiliary electronic pneumatic control (EPC) to perform column backflushing. This technique reverses the flow after target compounds elute, pushing heavy matrix components out of the inlet end without baking. Consequently, the analysis cycle time is significantly reduced from over 70 minutes to just 14.5 minutes.
| Column Dimensions | 30 m x 0.25 mm x 0.25 µm |
|---|---|
| Inlet Temperature | 250 °C |
| Oven Program Start | 75°C for 1 min |
| Oven Ramp Rate | 30 °C/min to 300 °C |
| Post-run Hold Time | 5 minutes at 280 °C |
| MS Source Temperature | 230 °C |
| Linearity Range | 10 to 200 µg/g |
| Correlation Coefficient | > 0.9996 |
The method reduces the GC run time from more than 70 minutes to 14.5 minutes.
The recoveries are greater than 95%, with specific results of 96.1% for cyanuric acid and 95.6% for melamine.