Trace analysis of perchlorate anion in selected food products by reverse-phase liquid chromatography-tandem mass spectrometry

Abstract

An alternative, rapid, and reproducible method of analysis for perchlorate in selected food products (fruit and vegetable juice, milk, and bottled water) was developed and validated. Improvements over previous methods were achieved by the use of a rugged and inexpensive C₁₈ column, a multi-mode OASIS HLB solid-phase extraction cartridge for sample clean-up, and acetic acid for pH adjustment and protein precipitation. The hydrophobicity of the perchlorate anion gives it good retention and separation characteristics on C₁₈ chromatographic columns. The C₁₈ column allowed for the use of 90% of acetonitrile at a low flow rate (0.3 ml min⁻¹), without splitting, and could also be regenerated with organic solvents, unlike an ion-exchange column. Perchlorate levels in selected commercial food samples were: <1.0–2.1 ng g⁻¹ (fruit and vegetable juices, reported here for the first time), <1.0–5.0 ng g⁻¹ (milk), and <1.0 ng g⁻¹ (bottled water).

Keywords:

• Perchlorate
• liquid chromatography-mass spectrometry
• juice
• milk
• water

Acknowledgements

The authors thank Dr Jeffrey Barach for reading the manuscript and for helpful suggestions.