This application note describes three methods for the determination of melamine in dairy products: an improved version of the U.S. FDA method, a high-throughput method using an Agilent Rapid Resolution LC (RRLC) system, and an alternative ion-exchange LC method. Due to the complexity of dairy product matrices, a cleanup step using solid phase extraction (SPE) is required for the above methods. The Agilent SampliQ SCX, a mixed-mode polymer SPE cartridge with combined reversed-phase and strong cation exchange properties, is used to successfully remove matrix interferences.
This document details the quantitative analysis of melamine in dairy products using three different liquid chromatography (LC) methods developed with Agilent 1120 Compact LC and 1200 Rapid Resolution LC systems. The first method is a modification of the U.S. FDA method using reversed-phase ion-pair chromatography. The second method utilizes an Agilent Rapid Resolution LC (RRLC) system to achieve high throughput, reducing analysis time by more than three times. The third method employs an alternative ion-exchange LC approach using a ZORBAX 300SCX column without ion-pair reagents.
| Column (Conventional) | ZORBAX SB-C8, 4.6 mm x 250 mm, 5 µm |
|---|---|
| Column (High-Throughput) | ZORBAX SB-C8 RRHT, 4.6 mm x 50 mm, 1.8 µm |
| Column (Ion Exchange) | ZORBAX 300SCX, 4.6 mm x 150 mm, 5 µm |
| Detection Wavelength | 240 nm |
| Instrumentation | Agilent 1120 Compact LC or 1200 LC |
The analysis uses an Agilent LC system, specifically the 1120 or 1200 series.
The Agilent SampliQ SCX mixed-mode polymer SPE cartridge is used to remove matrix interferences.
The high-throughput RRLC method reduces the LC run time to 6 minutes.