Quantitative HPLC-DAD Profiling of Ethanol Extracts of Rytiphlaea tinctoria and Laurencia spp. Collected from the Al-Hamamah Coast, Northeastern Libya

Marine red algae are a source of structurally diverse secondary metabolites with potential antioxidant and other biological activities. The present study was designed to compare the chromatographic profiles of ethanol extracts of the red macroalgae Rytiphlaea tinctoria and Laurencia spp. collected from the Al- Hamamah coast of northeastern Libya. Samples were collected on 15 May 2026 at 0–1.5 m depth, with three independent biological replicates per taxon. For each replicate, 10 g of dried algal material was extracted with 100 g of ethanol (1:10, w/w). The available laboratory record showed five principal chromatographic signals for each taxon, with retention-time ranges of 2.8–14.7 min for R. tinctoria and 3.5–15.4 min for Laurencia spp., monitored at multiple wavelengths. These observations demonstrate distinct chromatographic fingerprints between the two taxa. However, retention time and wavelength alone are insufficient for definitive compound identification. For quantitative reporting, authentic reference standards, calibration equations, linearity data, and validated sample calculations are required. Accordingly, the present manuscript separates the experimentally supported chromatographic observations from compound assignments and provides a complete framework for quantitative HPLC-DAD validation. Final compound concentrations should be reported as mg/g dry weight after insertion and verification of the original standard and instrument data.