Determination and comparison of mineral elements in traditional Chinese herbal formulae at different decoction times used to improve kidney function--chemometric approach.

Traditional Chinese herbal formulae Liu wei di huang (LW) (six-ingredient pill with Rehmannia) and Jin gui shen qi wan (JG) (kidney Qi pill from the golden cabinet) were analysed for Ca, Fe, Mg, Mn, Na, K and Zn at different decoction intervals by atomic absorption spectroscopy. LW and JG were used to improve the kidney function. JG was higher in all elements than LW. K (1691.29 - 2372.71 mg l(-1)) was highest in both formulae LW and JG followed by Ca (245.31 - 562.91 mg l(-1)). Ca, Fe, Mg, Mn and K were highest at 40 min for LW and Fe, Mn, Na and K were highest at 40 min for JG. Chemometrics such as principal component analysis, hierarchical cluster analysis and linear discriminate analysis were applied to classify the data and to understand the relation between the elements. Metal intake related to the consumption of decoction has also been studied. Mn made the highest contribution to average daily dietary intakes from the formulae.