Ethanol ar grade

The rhizomes were separated from KP plants (Rom-Kloa variety) cultivated in Chat Trakan district, Phitsanulok province, Thailand. The voucher specimen (No. VS001) was deposited in the Faculty of Pharmacy, Silpakorn University, Thailand. KP rhizomes were sun-dried, ground, and separated by sieves with size between 177 and 250 μm before being stored at 25 °C.
PMF, DMF and TMF standards were acquired from Indofine Chemical Company (Hillsborough, NJ, USA). Ethanol (AR grade) and methanol (HPLC grade) were purchased from RCI Labscan (Bangkok, Thailand) and Fisher scientific (Seoul, Korea), respectively. Acetic acid (AR grade) was bought from Merck KGaA (Darmstadt, Germany). Ultrapure water was processed by a TKA Pacific-UP/UPW water purification system (Niederelbert, Germany).

2-Diphenyl-1-picrylhydrazyl (DPPH), sodium acetate and quercetin were provided from Sigma Aldrich Chemical Co. (St Louis, MO, USA). Aluminium chloride, citric acid (≥99.7 %), ethylene glycol (≥99.5 %), fructose, glycerol, oxalic acid, urea (≥99 %), and sodium carbonate were taken from Kemaus (New South Wales, Australia). Folin-Ciocalteu's reagent and choline chloride (≥98 %) were obtained from Loba Chemie Pvt. Ltd. (Mumbai, India). Methanol (AR grade) and ethanol (AR grade) were purchased from RCI Labscan Ltd. (Bangkok, Thailand). Gallic acid (>99 %) was acquired from Merck Co. (Weiterstadt, Germany).

Ground beef from beef chuck (7 g fat/100 g meat) was purchased from a local market in Bangkok, Thailand. Six flavonoids, including kaempferol, myricetin, quercetin, morin, rutin, and taxifolin were purchased from Sigma (St. Louise, MO, USA). We obtained 2,2-diphenyl-1picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS), potassium persulfate, 37% hydrochloric and sodium acetate acid from Aldrich (Steinheim, Germany). TPTZ (2,4,6-tri (2-picridyl)-triazine, Iron (III) chloride hexahydrate, Iron (II) Sulfate Heptahydrate of Grade AR were purchased from QRec (Auckland, New Zealand).
EPA PAH8: (benz(a)anthracene (BaA), chrysene (Chry), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene (BaP), indeno(1,2,3-cd)pyrene (InP), dibenz(a,h)anthracene (DahA) and benzo(g,h,i)perylene (BghiP)) and QuEChERS kits were purchased from Supelco (Bellefonte, PA, USA). Internal standards (Acenaphthene-d10 and Chrysene-d12) were purchased from Dr. Ehrenstorfer (Augsburg, Germany), magnesium sulfate and sodium acetate were purchased from Ajax Finechem (Silverwater, NSW, Australia), all solvent high-performance liquid chromatography (HPLC) grade—(acetonitrile, methanol), ethanol (AR grade) and n-hexane (AR grade) were obtained from RCI Labscan (Bangkok, Thailand).