Phenol

The following reagents, 9-fluorenylmethoxycarbonyl (Fmoc) protected aa, O-(Benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate (TBTU), N,N′-dicyclohexylcarbodiimide (DDC) and 1-hydroxybenzotrazole (HOBt), were purchased from AAPPTEC (Louisville, KY, USA), ChemMatrix resin (0.60 mmol/g) from PCAS BiomMatrix Inc. (Saint-Jean-sur-Richelieu, QC, Canada), N,N-diisopropylethylamine (DIPEA), triisopropylsilane (TIS), Triton X-100, α-cyano-4-hydroxycinnamic acid (HCCA), methanol and absolute ethanol from Sigma-Aldrich (St. Louis, MO, USA), piperidine, pyridine, phenol, potassium cyanide, isopropyl alcohol (IPA), acetonitrile (ACN), N-methyl-2-pyrrolidone (NMP), trifluoroacetic acid (TFA) and diethyl ether from Panreac (Barcelona, Spain), acetic anhydride (Ac₂O), ninhydrin and ethanedithiol (EDT) from Merck (Boston, MA, USA) and dichloromethane (DCM) from The Dow Chemical Company (Bogotá, Colombia).

Avocado (Persea Americana L. var. Hass) seeds were supplied by Terravocado S.A. (Medellín-Colombia). The fresh potato tubers (Solanum tuberosum L., var. R12 Diacol Capiro) were supplied by the Instituto Colombiano Agropecuario (ICA, Colombia). The commercial fresh potatoes and palm oil (Oleollano, Villavicencio-Meta, Colombia; Lot L24082020F2TC YP) were purchased from a local market (Medellín, Colombia). The commercial French fries were purchased in a street food establishment (Medellín, Colombia). Acrylamide standard (99%), potassium hexacyanoferrate (II) trihydrate (98%, Carrez-I), and zinc acetate dehydrate (> 99%, Carrez-II) were obtained from Sigma (St. Louis, MO, USA). ¹³C₃-labelled acrylamide (99% isotopic purity) was obtained from Cambridge Isotope Laboratories (Andover, MA, USA). Formic acid (98%), methanol (99.5%), sulfuric acid (97%), phenol, anhydrous glucose and hexane were from Panreac (Barcelona, Spain). Sodium bisulfite was from Merck (Darmstadt, Germany) and glycerol from Bell Chem International S.A.S (Antioquia, Colombia). Deionized water was obtained from a milli-Q integral 5 water purification system (Millipore, Billerica, MA, USA). All other chemicals, solvents and reagents were of analytical grade.

The amino acid content was determined by HPLC (Waters) with fluorescence detection using precolumn derivatisation with 10 g of the product. The steps consisted of acidic hydrolysis in hydrochloric acid with 1% phenol (Panreac) at 100 °C for 24 h. Derivatisation of primary amino acids was performed with OPA/2-mercaptoethanol (Merck). Secondary amino acids were derivatised with 9-Fluorenylmethoxycarbonyl chloride (FMOC-Cl, Sigma-Aldrich) and HPLC separation was performed in a C18 column (20 cm length, 5 µm) [81 ].