GAS CHROMATOGRAPHIC DETERMINATION OF WATER IN NATURAL PRODUCTS BY REACTION WITH 2,2-DIMETHOXYPROPANE

The reaction between 2,2‐dimethoxypropane and water to form acetone and methanol was applied to the determination of water in natural products by GLC. Water was extracted from the natural products with methanol and analyzed with a column of 30% tetrahydroxyethylethylenediamine on diatomite, using cyclohexane as an internal standard. Peak area ratios were used to calculate the water content. A linear relationship exists between the ratios of the observed peak areas of acetone to the internal standard and the actual weight ratios of water to the internal standard. The water content of 24 natural products representing a variety of plant parts was analyzed by GLC utilizing the above reaction. The results compare well with those obtained by gravimetric and azeotropic methods. The new method is simple, rapid, and has a very good precision and accuracy. A major advantage of the method is that water estimation can be carried out using a flame‐ionization detector. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company