Estimation of Potassium by Flame photometry method

Estimation of Potassium Flame photometry method: 

 Total Potassium are usually determined by dry ashing at 650-700 Degree Centigrade and dissolving in concentrated hydrochloric acid. 

Reagent and Standard 

 (1) Potassium chloride standard solution: Make a stock solution of 1000 ppm K by dissolving 1.909 g. of AR grade potassium chloride (dried at 60oC for 1 h) in distilled water and diluting up to 1 litre. Prepare 100 ppm standard by diluting 100 ml of 1000 ppm stock solution to 1 litre with extracting solution. 

(2) Standard : Pipette 0,5, 10,15 and 20 ml of 100 ppm solution into 100 ml volumetric flasks and make up the volume upto the mark. The solution contain 0, 5, 15 & 20 ppm K respectively. 

Procedure: 

•  Take 5g sample in a porcelain crucible and ignite the material to ash at 650-700 C in a muffle furnace. 
• Cool it and dissolve in 5 ml concentrated hydrochloric acid, transfer in a 250 ml beaker with several washing of distilled water and heat it.
•  Filter the solution and dilute the filtrate 100 ml with distilled water in 100 ml volumetric flask.

 Determine K by flame photometer using the K- filter after necessary setting and calibration of the instrument.

Calculation: Potash (K) %by weight = R X 20 X diluting factor, 

where R= ppm of K in the sample solution