Arthrospira platensis Pigment Extraction

The dry biomass sample was prepared for extraction by weighing approximately 20 mg of Arthrospira platensis into a 2 mL plastic bottle with a cap (Eppendorf type). Then, 1.5 mL of 50% methanol (Lichrosolv, HPLC gradient grade, Merck KGaA, Darmstadt, Germany) was added to the sample, along with ultrapure water with a conductivity of 0.055 µS (v/v). The sample was subjected to ultrasonic extraction in a bath for 1 h, followed by centrifugation. The resulting extract (0.5 mL) was filtered using PTFE filters (0.45 µm, Thermo Fisher Scientific Inc., Waltham, MA, USA) prior to chromatography. Two parallel extractions were prepared.
Chromatographic determination was performed using an Agilent 1200 liquid chromatograph equipped with a diode array detector. The analytical column used was a Supelcosil ABZ + Plus column (150 mm × 4.6 mm, 5 µm, Supelco, Darmstadt, Germany), thermostated at 25 °C. A gradient of acetonitrile (Lichrosolv, HPLC gradient grade, Merck KGaA, Darmstadt, Germany) and ultrapure water (conductivity of 0.055 µS) was employed, with the addition of 0.1% trifluoroacetic acid (Trifluoroacetic acid, suitable for HPLC ≥ 99.0%, Merck KGaA, Darmstadt, Germany) to both solvents. The gradient profile included 20% acetonitrile at 0 min, which increased to 46% at 20 min, with a total chromatography time of 25 min at a flow rate of 1 mL min⁻¹. Detection was performed at a wavelength of 238 nm.