This standard specifies the method for the determination of silicic acid using the silicon-molybdenum yellow colorimetric method. This standard is applicable to the determination of the content of soluble silicic acid in groundwater that can react with ammonium aluminate, and the results are expressed in the form of metasilicic acid. The minimum detection volume is 33ug, and the optimal measurement range is 1.3~26mg/L. Phosphate interferes with the determination, and adding oxalic acid can eliminate its interference. When the water contains sulfide, it can reduce the silicon-molybdenum yellow to yellow-green and interfere with the measurement. You can first add oxidant (potassium permanganate) to oxidize the sulfide, and then reduce the excess potassium permanganate with 10% sodium nitrite. Add ammonium molybdate solution to develop color or use silicon molybdenum blue reduction method for measurement.
DZ/T 0064.62-1993 history
1970DZ/T 0064.62-2021 Methods of analysis of groundwater quality - Part 62: Determination of silicic acid by silicon molybdenum yellow spectrophotometric method
1993DZ/T 0064.62-1993 Groundwater Quality Testing Method for Determination of Silicic Acid by Silicon Molybdenum Yellow Colorimetric Method