Sub–1 min separation in sequential injection chromatography for determination of synthetic water-soluble dyes in pharmaceutical formulation
Sequential Injection Chromatography (SIC) evolved from fast and automated non-separation Sequential Injection Analysis (SIA) into chromatographic separation method for multi-element analysis. However, the speed of the measurement (sample throughput) is due to chromatography significantly reduced. In this paper, a sub–1 min separation using medium polar cyano monolithic column (5 mm × 4.6 mm) resulted in fast and green separation with sample throughput comparable with non-separation flow methods The separation of three synthetic water-soluble dyes (sunset yellow FCF, carmoisine and green S) was in a gradient elution mode (0.02% ammonium acetate, pH 6.7 – water) with flow rate of 3.0 mL min−1 corresponding with sample throughput of 30 h−1. Spectrophotometric detection wavelengths were set to 480, 516 and 630 nm and 10 Hz data collection rate. The performance of the separation was described and discussed (peak capacities 3.48–7.67, peak symmetries 1.72–1.84 and resolutions 1.42–1.88). The method was represented by validation parameters: LODs of 0.15-0.35 mg L−1, LOQs of 0.50–1.25 mg L−1, calibration ranges 0.50-150.00 mg L−1 (r > 0.998) and repeatability at 10.0 mg L−1 of RSD ≤ 0.98% (n = 6). The method was used for determination of the dyes in “forest berries” colored pharmaceutical cough-cold formulation. The sample matrix – pharmaceuticals and excipients were not interfering with vis determination because of no retention in the separation column and colorless nature. The results proved the concept of fast and green chromatography approach using very short medium polar monolithic column in SIC.