Determination of Phytic Acid in Cottonseed Kernels by Ion Chromatography

Cottonseed meal is an important plant protein resource of feed industry and breeding industry, although it contains many antinutritional factors. Phytic acid, as one of the mainly antinutritional factor, cannot be digested easily by monogastric animals, such as fowls and pigs, consequently results in the decreased bio-availability of material elements and leads to the environment pollution by the phytate in excreta. Thus far, study of breeding cottons containing low phytic acid gradually becomes the hotspot, and the method of fully extracting phytic acid from cotton seeds and precise measurement is becoming more and more important and necessary. A new method for the rapid extraction and determination of phytic acid in cottonseed kernels by ion chromatography was developed in this study. After the diethyl ether treatment of dry cottonseed kernel powder, the samples were suspended in 10ml 0.66 mol·L^－1 HCl and boiled for 1 hour. Then the samples were shaken at 4 ℃ for 12 hours and centrifuged. The supernatant was diluted and purified for loading. To analyze the sample, DIONEX ICS-2000 ion chromatography, AG11-HC Guard (4 mm×50 mm) protection column and AG11-HC Guard (4 mm×250 mm) separation column were used in controlled conditions (washing buffer: 30.0 mmol·L^－1 KOH; ream speed: 1.0 mL·min^－1; collecting time: 25 min; 75 mA current; temperature: 30 ℃; loading amount: 20 μL). The results showed that R2 of linear regression is 0.999, which means the regression relation is great. In addition, the standard deviations of all the indexes are within 5% and the average recovery rate is 98.64%-102.31%. The detection limit, showing the minimum detectable concentration of analyte in the sample, is 0.059 μg·mL^－1, and the quantitation limit, showing the minimum amount of analyte in a sample can be quantitatively determined, is 0.196 μg·mL^－1. This method is easy and accurate with great reproducibility, showing a strong application value.