TY - JOUR
T1 - Interference from arsenate when determining phosphate by the malachite green spectrophotometric method
AU - Linge, K.L.
AU - Oldham, Carolyn
PY - 2001
Y1 - 2001
N2 - The effect of arsenate on phosphate determination by the malachite green spectrophotometric method was investigated. The molar absorptivities of the molybdophosphate and malachite green-molybdoarsenate species at 625 nm and a final acidity of 0.38 M were calculated as 10.4 +/- 0.13 x 10(4) and 7.2 +/- 0.17 x 10(4) 1 mol(-1) cm(-1) respectively, indicating that arsenate could interfere in phosphate measurement. Arsenate concentrations as low as 23 mug 1(-1) caused increase in colour development in phosphate solutions. However, the extent of colour development for both anions depended on the final acid concentration of the solution. An acidified sodium sulphite solution (0.83 M NaSO3, 0.83 M H2SO4) quantitatively prevented arsenate colour development up to 300 mug 1(-1) As(V). It was also demonstrated that the method removed As(V) interferences in mixed As/P solutions and therefore can be used to treat natural water samples with elevated arsenate concentrations before phosphate measurement. (C) 2001 Elsevier Science B.V. All rights reserved.
AB - The effect of arsenate on phosphate determination by the malachite green spectrophotometric method was investigated. The molar absorptivities of the molybdophosphate and malachite green-molybdoarsenate species at 625 nm and a final acidity of 0.38 M were calculated as 10.4 +/- 0.13 x 10(4) and 7.2 +/- 0.17 x 10(4) 1 mol(-1) cm(-1) respectively, indicating that arsenate could interfere in phosphate measurement. Arsenate concentrations as low as 23 mug 1(-1) caused increase in colour development in phosphate solutions. However, the extent of colour development for both anions depended on the final acid concentration of the solution. An acidified sodium sulphite solution (0.83 M NaSO3, 0.83 M H2SO4) quantitatively prevented arsenate colour development up to 300 mug 1(-1) As(V). It was also demonstrated that the method removed As(V) interferences in mixed As/P solutions and therefore can be used to treat natural water samples with elevated arsenate concentrations before phosphate measurement. (C) 2001 Elsevier Science B.V. All rights reserved.
U2 - 10.1016/S0003-2670(01)01388-5
DO - 10.1016/S0003-2670(01)01388-5
M3 - Article
SN - 0003-2670
VL - 450
SP - 247
EP - 252
JO - Analytica Chimica Acta
JF - Analytica Chimica Acta
IS - 1-2
ER -