Abstract:

An analytical method was developed for the determination of 5 macro elements including Na, Mg, P, K and Ca in
okra by inductively coupled plasma optical emission spectrometry (ICP-OES) with hydrochloric acid extraction. The effects
of different extraction conditions including HCl concentration, extraction method and extraction time on extraction efficiency
were investigated. The accuracy and precision of this method were confirmed by using the reference standard material tea
(GBW 08513). Under the optimum conditions, the standard curve of each element exhibited a good linear correlation with
a coefficient higher than 0.999 3. The detection limits for the 5 elements were in the range of 3.88–12.26 μg/L, with relative
standard deviations (RSDs) between 1.55% and 3.91%. A satisfactory result was obtained when the proposed method was
applied to analyze real samples. Okra contained abundant amounts of nutrient elements, with K being the most predominant
element, followed by P and Ca. The method was simple and accurate, and could be used for the determination of the 5 macro
elements in okra.

Key words: okra, hydrochloric acid extraction, inductively coupled plasma optical emission spectrometry, macro elements