LAUSR

&NA; The extraction of phenolic compounds from 4 different sea algae samples, three brown algae (Cystoseira abies‐marina, C. abies‐marina grinded under cryogenic conditions with liquid nitrogen, Undaria pinnatifida and Sargassum muticum) and one red algae (Chondrus crispus) via solid phase extraction using micro‐elution solid‐phase extraction (&mgr;‐SPE) plate method was studied. Prior to &mgr;‐SPE, 50 mg of algae with 80% methanol mixture was extracted in hyphenated series by various extraction techniques, such as pressurized liquid extraction and Ika Ultra‐Turrax® Tube Drive, in combination with ultrasound assisted extraction. The &mgr;‐SPE plate technique reduced the time of sample pre‐treatment thanks to higher sensitivity and pre‐concentration effect. Selected groups of benzoic acid derivatives (p‐hydroxybenzoic, protocatechuic, gallic, vanillic, and syringic acids), hydroxybenzaldehydes (4‐hydroxybenzaldehyde, and 3,4‐dihydroxybenzaldehyde), and cinnamic acid derivatives (p‐coumaric, caffeic, ferulic, sinapic, and chlorogenic acids) were determined using rapid resolution liquid chromatography coupled to mass spectrometry detection with negative ion electrospray ionization (RRLC‐ESI–MS) using multiple reactions monitoring. LOQs of measured samples varied in the range 0.23–1.68 ng/mL and LODs in the range 0.07–0.52 ng/mL. The applied method allowed a simultaneous determination of phenolics (i.e. free, esters soluble in methanol, glycosides, and esters insoluble in methanol) in less than 5 min (including alkaline or acidic hydrolysis of raw extracts) from sea algae extracts. HighlightsDifferent extraction techniques were compared for phenolic extraction from algaeSPE was compared with &mgr;‐SPE plate for the isolation of phenolics from algaeThe phenolic identification and quantification was performed by RRLC‐ESI‐MS/MSThe applied method allowed the analysis of phenolics from algae in less than 5 minThe method let the analysis of 14 phenolic acids from algae in subnanomolar contents