The determination range of the silicate detector is generally 0-50ug/L, the basic error is ±5% of the full scale of 50ug/L, and the principle is to reduce the soluble silicon in water to ammonium molybdate by the yellow complex generated by the soluble silicon in water, reduce it to silicon molybdenum blue with a reducing agent, and then determine it by silicate detector.
To improve the sensitivity and accuracy of the instrument, you can use a special long cuvette. The measurement is then made using the difference colorimetry.
<h1 class="pgc-h-arrow-right" data-track="3" > reagents used in silicate detectors</h1>
1. Ammonium molybdate solution
Weigh 50g of ammonium molybdate dissolved in about 500mL of primary reagent water. Take 42 mL sulfuric acid (relative density 1.84) and add it to 300 mL of primary reagent water under continuous stirring and cool to room temperature. The ammonium molybdate solution is added to the sulfuric acid solution and the volume is fixed to 1L with primary reagent water. Keep in polyethylene plastic bottles.
2. Reducing agent
Weigh 1.5g1-amino-2 naphthol-4-sulfonic acid and 7g sodium anhydrous sulfite, dissolved in about 200mL of primary reagent water. Weigh 90g of sodium bisulfite and dissolve in 600mL of primary reagent water. After mixing the two liquids, dilute them with primary reagent water to 1 L, and should be filtered and used when the solution is cloudy. Keep in the refrigerator with polyethylene plastic bottles.
3. Tartaric acid solution (100g/L)
<h1 class="pgc-h-arrow-right" data-track="9" > detection steps</h1>
Take a water sample of 100mL into a plastic cup, add 3mL of ammonium molybdate solution, mix and place for 5min, add 3mL tartaric acid solution, mix and place for 1min; add 2mL reducing agent, and place for 8min after mixing. Fill the colorimetric solution with the cuvette, turn on the reading switch, and the value displayed on the detection instrument is the silicon content in the water.
<h1 class="pgc-h-arrow-right" data-track="11" > considerations for detection</h1>
1. The reagents used in the test are kept in the drug refrigerator as much as possible.
2. The drug refrigerator should be kept away from the heat source when used and placed, and the distance from the wall is greater than 10cm, and the temperature regulation cannot be adjusted too low at one time.
3. If the evaporator of the drug refrigeration box is thicker, press the frost key, or the power is cut off for a period of time, so that the frost dissolves itself, and cannot be scraped with metal or other hard objects.
4. Check and record the temperature of the refrigerator once a day, defrost if necessary, and clean the refrigerator once a month.
5. The prepared agent should indicate the name and date of preparation.
6. Water samples are added to tartaric acid or oxalic acid masking agents, which can prevent the interference of phosphate and a small amount of iron ions in the water sample.
7. When the color of the reducing agent solution darkens or there is precipitation, it means that the reducing agent has begun to fail. It needs to be reconstituted for use.