High-Throughput Determination of Quinine in Beverages and Soft Drinks Based on Zone-Fluidics Coupled to Monolithic Liquid Chromatography

Abstract

In the present study we propose a new automated analytical scheme for the determination of quinine in soft drinks and beverages by coupling zone-fluidics (ZF) to liquid chromatography (LC). Certain pretreatment tasks involving precise liquid handling, such as sample dilution and addition of the internal standard (ISTD) were automated by ZF. After on-line filling of the loop of the LC injection valve, separation was carried out in less than 2.5 min by using a reversed phase monolithic column (100 × 4.6 mm i.d.) at a flow rate of 2 mL min⁻¹. The ZF and LC parts of the setup operated independently: during LC separation the next sample was treated by ZF allowing a high throughput of 24 h⁻¹. The proposed assay was thoroughly validated in terms of linearity (up to 150 mg L⁻¹), LOD (0.25 mg L⁻¹), LOQ (0.8 mg L⁻¹), precision, accuracy, and ruggedness. The ZF-LC method was successfully applied for the determination of quinine in beverages and soft-drinks.

Keywords:

• Determination
• High performance liquid chromatography
• Monolithic column
• Quinine
• Zone-fluidics

Acknowledgments

This article is part of a Special Issue on Automated Flow Injection Techniques organized by Dr. Paraskevas Tzanavaras of Aristotelian University of Thessaloniki, Greece.

Notes

^a See the General Procedure section.

^b N per column meter.

^a Mean value (±SD) of five replicates.

^b Mean value (±SD) of three sub-samples.