| | Methods/reagent | Optimized or recommended conditionsa | Analytesb | Ref./year |
| | (A) Acid-catalyzed esterification/transesterification | | Anhydrous methanolic hydrogen chloride | Reflux, 2 h or 50°C, overnight (5% HCl) | Other than FFA | [11] 1993 | | 50°C, 30 min (5% HCl) | FFA | | Conc. HCl/methanol/toluene | 45°C, 8 h (1.2% HCl)c | TG, PhL | [12] 2010 | | 45°C, 14 h (0.6% HCl) | TG, PhL | | 45°C, 16 h (1.2% HCl) | SE | | 45°C, 20 min (0.5% HCl) | FFA | | 45°C, 60 min (0.2% HCl) | FFA | | 100°C, 30 min (1.2% HCl) | TG, PhL | | 100°C, 90 min (1.2% HCl) | SE | | 100°C, 5 min (0.2% HCl) | FFA |
| | (B) Esterification/transesterification by BF3-methanol or modified BF3-methanol | | BF3-methanol | 100°C, 2 min (14% BF3) | FFA | [13] 1964 | | BF3-methanol/onert solvent | 100°C, 30 min (25% BF3)d 100°C, 45 min (35% BF3)d | TG SE | | NaOH saponification/methanolic BF3 | 100°C, 5 min (0.5 N NaOH)/100°C, 2 min (12.5% BF3) | Cottonseed oil | [14] 1966 | | 100°C, 5 min (0.5 N NaOH)/100°C, 30 min (14% BF3) | Lipids in foods | [15] 2017 KFDA | | KOH saponification/acidification/methanolic BF3 | 70°C, 1 h (0.5 M KOH)/2 M HCl/RT, 20 min (15% BF3) | Lipid mixture | [16] 1996 | | Hydrolysis by HCl/methanolic BF3 | 80°C, 40 min (8.3 M HCl)/100°C, 45 min (7% BF3) | TG, FFA in foods | [17] 2002 AOAC |
| | C. Alkali-catalyzed transesterification | | Anhydrous sodium or potassium methoxide | 50°C, 10 min (0.5 to 2 M CH3ONa, 100-fold excess) | TG | [11] 1993 | | 50°C, 5 min | PhL | | 50°C, 1 h | SE | | Methanolic NaOH or KOH | RT, 2 min (2 M KOH)e | TG | [16] 1996 | | 37°C, 1 min (2 M KOH)e | TG | | RT, 15 h (0.1 M KOH)e | TG | | 37°C, 1 h (0.5 M NaOH)c,f 37°C, 40 min (0.5 M NaOH)c,f | SE wax | [18] 2003 |
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aYield of FAME: 97%∼100%. bAnalytes are lipids: TG, triglyceride; FFA, free fatty acid; SE, sterol ester, cholesteryl ester; PhL, phospholipids. cConcentration in final volume. d, e, fInert solvent is added: d, benzene; e, hexane; f, methyl propionate.
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