Organic solvent-free matrix solid phase dispersion (MSPD) for determination of synthetic colorants in chilli powder by high-performance liquid chromatography (HPLC-UV)

Abstract

A green and simple organic solvent-free matrix solid phase dispersion (MSPD) was developed and applied to the extraction of four synthetic colorants (amaranth, sunset yellow, allura red and erythrosine) in chilli samples. High-performance liquid chromatography (HPLC) coupled with ultraviolet (UV) detection was used for the separation and determination of the analytes. The chromatographic separation was performed on a Phenomenex Luna C18 (2) 100A column in a gradient using methanol/water as the mobile phase at a flow rate of 0.8 mL min⁻¹ and 35 °C of temperature. Factors such as the type of dispersant, the ratio of sample to dispersant, and the type, volume, pH value and ionic strength of elution solvent were investigated. Under the optimum experimental conditions, the linearities for determining the analytes were in the range of 30–2000 ng g⁻¹ for amaranth and erythrosine, 20–2000 ng g⁻¹ for sunset yellow and allura erythrosine. Limits of detection ranged between 8.6 and 13.5 ng g⁻¹. No organic solvents were used in the extraction procedure, and 4 mL water directly eluted the analytes. Thus, the method avoided environmental pollution of organic solvents and removed multi-step procedures in the sample pretreatment and has potential to be applied using a simple instrument presented in most analytical laboratories.