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Journal of Analytical Methods in Chemistry
Volume 2016, Article ID 7213542, 7 pages
Research Article

Measurement of Total Free Iron in Soils by H2S Chemisorption and Comparison with the Citrate Bicarbonate Dithionite Method

1Anxi College of Tea Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
2Department of Leisure, Recreation and Tourism Management, Tzu Hui Institute of Technology, Pingtung 926, Taiwan
3Sustainable Environment Research Laboratories, National Cheng Kung University, Tainan 701, Taiwan
4Fujian Provincial Technology Development Base of Tea Industry, Anxi 362406, China

Received 19 August 2016; Accepted 1 December 2016

Academic Editor: Ricardo Jorgensen Cassella

Copyright © 2016 Shui-Sheng Fan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Free iron is one of the major analytical items for soil basic properties. It is also an important indicator for understanding the genesis of soil, soil classification, and soil distribution behavior. In this study, an alternative analytical method (chemisorption) based on thermodynamic knowledge was proposed for measurement of total free iron oxides in soils. Several representative soil samples belonging to alfisols, ultisols, inceptisols, and entisols were collected from Taiwan and tested by the chemisorption, and the estimated total free iron oxides were compared with those measured from the traditional citrate bicarbonate dithionite (CBD) method. Experimental results showed that the optimal operating temperature was found to be at 773 K and the carbon monoxide (CO) is the best gaseous reagent to promote the formation of FeS. The estimated total free iron oxides for soil samples determined from the chemisorption in the presence of CO were very close to those from the CBD technique. The result of regression indicates that the estimated total free iron is strongly correlated with the CBD-Fe content () in the presence of CO.