Chlorophylls and β‐carotene in <i>Spirulina platensis</i> Dietary Supplements: Nano Liquid Chromatography Versus Diffuse Reflectance Spectroscopy for Establishing Composition, Quality Control, and Comparison of Commercial Products

Spirulina is considered a superfood due to its chlorophylls. Two new methods for the determination of chlorophylls and β-carotene were developed here, one based on in-tube solid-phase microextraction (IT-SPME) coupled online to nanoliquid chromatography (nanoLC) with diode array detection (DAD), and the other on ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). A protocol to extract the pigments from spirulina was proposed using ethanol (1.5 mL). The aim is to provide fast and environmentally friendly techniques for both the extraction and measurement of pigments, generating little waste and low energy expenditure. IT-SPME-nanoLC-DAD and UV-vis DRS showed good linearity up to 300 or 600 µg/L and 50 mg/L, with instrumental detection limits between 10 and 50 µg/L and 2 and 5 mg/L, respectively. The % intraday and interday relative standard deviation were between 2 and 9. The HEXAGON tool is used for assessing greenness and sustainability for three scenarios: establishing composition, quality control, and comparison of seven dietary supplements.