MPT-AES Determination of Phosphorus in Cross-linked Starch

Phosphorus in cross-linked starch sample was determined by microwave plasma torch (MPT)-AES,using argon as the working and carrier gas and oxygen as the shielding gas.It was shown that acidity of testing sample solution should be kept below 0.03 mol·L-1,and that co-existing Na+-ion should be removed from the starch sample by washing to eliminate its interference.Under the optimized conditions,it was found that highest sensitivity and intensity were attained by choosing the analytical spectral line of 253.565 nm,and by working at the flowrate of 1.5 and 0.27 L·min-1 for the carrier gas and working gas.Detection limit (3S/N) found for the method was 0.02 μg·L-1.By parallel analysis of cross-linked starch sample for its phosphours content by the present method and by ICP-AES,consistent analytical results and values of RSD′s (n=5) were obtained.It was proved that the MPT-AES was feasible to be used for less energy consumption and lower operation cost as compared with ICP-AES.