Determination of Phosphorus in Soil by ICP-OES Using an Improved Standard Addition Method

Table 5

Comparison of the determined results of total P by ISAM with standard solutions diluted by soil digestion solution of GSS-14 and by the soil mixture solution.

Sample	Standard solutions diluted by soil digestion solution of GSS-14		Standard solutions diluted by the soil mixture solution		Certified value
	Total value obtained by ISAM (mg/kg)	△1^a	Total value obtained by ISAM (mg/kg)	△2^b	(mg/kg)
GSS-5	370	20	396	6	390 ± 34
GSS-8	776	1	765	10	775 ± 25
GSS-14	734	4	717	13	730 ± 28
GBW (E) 070041	544	20	530	6	524 ± 26.2

^a△₁ = the value obtained by ISAM with the standard solutions diluted by soil digestion solution of GSS-14—certified value; ^b△₂ = the value obtained by ISAM with the standard solutions diluted by the soil mixture solution—certified value.