Determination of glycerol

Polyhydric alcohols with hydroxyl groups on three or more adjacent carbon atoms are oxidised by periodate, yielding aldehydes from the end 

Glycerol can be determined by measuring the formaldehyde or formic acid produced or the periodate consumed. In this method the formic acid is measured. The weight of glycerol present must not exceed 0.4 g. 

Transfer the aqueous layer from the extraction of fatty acid (or an aliquot) to a stoppered conical flask and neutralise to phenol red with 1.0 M sodium hydroxide. 

Add about 1 ml 1 M hydrochloric acid and boil for 1 min (caution flammable vapour will be given off) to expel carbon dioxide. 

Cool and accurately neutralise with 0.1 M sodium hydroxide. 

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The methods of analysis of the American Oil Chemists Society (AOCS) are the principal procedures followed in the United States and Canada and are official in commercial transactions. When the material is for human consumption or drug use, it must meet the specifications of the USP (12). Commercial distilled grades of glycerol do not require purification before analysis by the usual methods. The determination of glycerol content by the periodate method (13), which replaced the acetin and dichromate methods previously used, is more accurate and more specific as well as simpler and more rapid. 

Caputi et al. (29) conducted a collaborative study for the determination of glycerol in wine and grape juice. This method uses a strong cation-exchange type of column (H form), degassed water as the mobile phase, and an RI detector. The glycerol was determined on samples simply after filtration (0.45 gm) and with an external standard. For wines, the authors obtained a repeatability of 1.25% and a reproducibility of 2.79% (Reprinted from Ref. 1, p. 566, by courtesy of Marcel Dekker Inc.). 

G Sanchez Munoz, E Garcia Romero, MS Perez Coello, PJ Martin Alvarez. Determination of glycerol in wines by high-performance liquid chromatography comparison with enzymatic method. J Chromatogr 623 43-47, 1992. 

A Caputi Jr, E Christensen, N Biedenweg, S Miller. Liquid chromatographic method for determination of glycerol in wine and grape juice collaborative study. J AOAC Int. 75(3) 379-383, 1992. 

A tribenzoyl derivative was used by Decroix et al. [6] for the determination of glycerol. The preparation of the derivative was carried out directly in the sample as it does not require strictly anhydrous conditions. After performing the extraction with diisopropyl ether and after evaporating the solvent, the derivative dissolved in chloroform was injected. A detection limit of 1 pg of glycerol was reported. The low thermal stability of the derivative is a drawback. 

K. Matsumoto, et. al.. Determination of glycerol in wine by amperometric flow injection analysis with an immobilized glycerol dehydrogenase reactor, Agric. Biol. Chem. 55 (4), 1055-9 (1991). 

D. Betteridge, J. Ruzicka, The determination of glycerol in water by flow-injection analysis. A novel way of measuring viscosity, Talanta 23 (1976) 409. 

Determination of glycerol and propylene glycol in cigarette smoke 18th Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 18,... 

Plank, C. E. Lorbeer. Simultaneous determination of glycerol, and mono-, di-, and triglycerides in vegetable oil methyl esters by capillary gas chromatography. /. Chrorrutogr., A 1995, 697, 461-468. 

D. Betteridge and J. Rdii5ka, The Determination of Glycerol in Water by Flow Injection Analysis—A Novel Way of Measuring Viscosity. Talanta, 23 (1976) 409. 

Table 3. Results from the determination of glycerol trinitrate, nitroguanidine and dibutylphtalate in propellant. ... 

Luca GC, Reis BE, Zagatto EAG, et al. (2002) Development of a potentiometric procedure for determination of glycerol and 2,3-butanediol in wine by sequential injection analysis. Analytica Chimica Acta 366 193-199. 

The determination of glycerol and other polyalcohols which form formaldehyde, on oxidation with periodic acid, can be modified< ) so that formaldehyde need not to be separated by distillation. The excess of periodate can be removed by adding an excess of arsenite (in about 1 4 ratio) in a medium of 2 m HCl. When made alkaline, the wave of formaldehyde can be recorded it is unaffected by the presence of either arsenic (HI) or (V). 

Fig. 9-126. Determination of glycerol in soap. - Separator column lonPac ICE-ASl eluant 50 mmol/L HCIO4 flow rate 1 mL/min detection pulsed amperometry on a platinum electrode injection 50 pL sample (1 500 diluted) peak (1) 6.2 mg/L glycerol.

Additional information can be gained by reduction and hydrolysis of the oxidation products resulting from the action of periodate. Information concerning the position of the linkages in dextrans was derived by analytical determinations of glycerol, erythritol, and glucose, which result, respectively, in this way from 1— 6, 1—>4, and 1—>3 linked glucopyranoses (S7). 

Spinella, C. j., and M. Mager Modified enzymatic procedure for the routine determination of glycerol and triglycerides in plasma. J. Lipid Res. 7, 167 (1966). 

Considerable literature has been published on the determination of glycerol oxidation methods are the most satisfactory but obviously they depend upon its separation in a fair state of purity. Any process which involves evaporation of aqueous or alcoholic solutions to low bulk gives rise to inaccuracies as concentration is difficult and glycerol is sensibly volatile at 100, the amount of loss varying with the conditions and the apparatus used. The volatilisation may be prevented by the presence of an excess of lime with which glycerol forms a compound. 

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