Ca. Deabreu et al., EXTRACTION OF BORON FROM SOIL BY MICROWAVE-HEATING FOR ICP-AES DETERMINATION, Communications in soil science and plant analysis, 25(19-20), 1994, pp. 3321-3333
Extraction with hot water is the most widely used procedure to determi
ne boron (B) in soils for the diagnosis of the nutrient availability f
or plants. However, this procedure is tedious for routine conditions a
nd requires some special precautions. An alternative extraction proced
ure was developed, consisting in the extraction of B with a 1.25 g/L s
olution of barium chloride (BaCl2) or with water heated in a domestic
microwave oven. Boron was determined either by inductively coupled arg
on plasma emission spectrometry (ICP-AES) and by spectrophotometry wit
h azomethine-H. Good correlations were found between the extraction by
boiling water under reflux and the extraction by the microwave heatin
g for 13 Brazilian soils, and the contents of B obtained by spectropho
tometry did not differ significantly from those obtained by ICP-AES. C
onsidering the calculated standard deviations, it can be concluded tha
t microwave heating followed by ICP-AES determination is an adequate p
rocedure for the determination of hot water extractable B in soils.