Introduction to Analytical Instruments

To determine potassium and sodium ions in water, ion chromatography may be the best option; additionally, potassium ions can be measured using a potassium-selective electrode. When it comes to measuring arsenic, the measurement itself is not the difficult part; rather, sample processing for sulfur is the challenge. The key lies in how to process sulfur samples reliably and ensure the representativeness of the arsenic measurements – analytical instruments and methods are relatively less important in this regard.

For both analyses, it is possible to choose between atomic absorption flame (K, Na) and graphite furnace (As) methods for determination. Treatment of sulfur sample: For the treatment of the sample, accurately weigh 2.0000 g of the ground sulfur sample (the exact amount depends on the concentration of the sample) and place it in a 100 ml Erlenmeyer flask. Add 20 ml of 85% sulfuric acid to the flask, then place it on an electric furnace. Adjust the heating temperature of the furnace until white smoke appears inside the flask; wait until the white smoke reaches the mouth of the flask. This evaporation process should be carried out in a fume hood. When the volume of liquid remaining in the flask is approximately 1 ml, remove it from the furnace and allow it to cool. Transfer the solution to a 50 ml volumetric flask and dilute it to the mark using deionized water. Shake well before analysis. A blank solution should also be prepared under the same conditions as described above.

I’d like to ask again: is this based on that standard, or is there some other basis? Could you provide it?