The use of lanthanum chloride to prevent interferences in the flame photometric determination of exchangeable calcium in soils

An examination of the interferences of aluminium, bicarbonate, phosphate, sulphate and silicate in the flame photometric determination of calcium in ammonium chloride solutions has shown that, with the exception of bicarbonate, all cause serious interference. Addition of lanthanum to the solution can satisfactorily prevent each of these interferences Provided the lanthanum to aluminium ratio is at least 12.5 I by weight all interference from aluminium can be prevented The use of lanthanum chloride to prevent such interferences in the determination of calcium in ammonium chloride lcachates of soils is discussed and a simple flame photometric method for the determination of exchangeable calcium in soils is proposed.