Limit Tests Arsenic

In short, all prescribed tests for impurities in the Pharmacopoeia usually fix certain limits of tolerance. For lead, arsenic and iron general quantitative or limit tests are precisely laid down which, with necessary variations and modification are rigidly applicable to pharmaceutical substances. 

Materials Required Arsenic limit test apparatus HgCl2—paper smooth white filter paper (having thickness in mm of 400 paper = weight in g per Sq. M.), soaked in a saturated solution of HgCl2, pressed to get rid of excess of soln. and dried at about 60°C in the dark lead acetate solution 10.0% w/v soln. of PbAc2 in C02 free water KI (AsT), 1.0 g Zn (AsT) 10.0 g Dilute Arsenic solution (AST) Standard stains, Test Solutions—are prepared according to the Indian Pharmacopoeia 1996. 

How will you carry out the limit tests for acid radical impurities e. g., Cl- S041 2 3 4 5-, CO32-, CN-, NO3-, Arsenate, Oxalate and Phosphate ... 

The suggested international limit for arsenic of 0.2 mg/liter should not be difficult to meet. Arsenate insecticides are not used in the United States and are seldom used abroad. While simple tests for the presence of arsenic are available, its quantitative determination is time consuming, involving ashing, special equipment, and meticulous technique and cleanliness. 

Arsenic Determine as directed under Arsenic Limit Test, Appendix IIIB, using a Sample Solution prepared as directed for organic compounds. 

Method II (Sample Preparation) Transfer approximately 0.2 g of sample, accurately weighed, into the titration flask. The stoichiometric factor (Fs) for Allura Red is 8.06. Arsenic Determine as directed under Arsenic Limit Test, Appendix MIR, using a Sample Solution prepared as directed for organic compounds. 

Arsenic Determine as directed under Arsenic Limit Test, Appendix IIIB, using a solution of 1 g of sample in 35 mL of water. Fluoride Determine as directed in Method /Funder the Fluoride Limit Test, Appendix IIIB, using a 2-g sample, Buffer Solution B, and 0.1 mL of Fluoride Standard Solution. 

Sample Preparation Transfer 5 g of sample into a 250-mL Erlenmeyer flask, and continue as directed in the second full paragraph for Sample Solution under Arsenic Limit Test, Appendix IIIB, beginning with add 5 mL of sulfuric acid and a few glass beads. After the sample has been digested and the solution diluted to 35 mL, as directed therein, add 1 mL of a 1 25 solution of potassium permanganate, and mix. 

Arsenic Transfer 10.0 g of sample into a 250-mL beaker, add 50 mL of 0.5 N hydrochloric acid, cover with a watch glass, and heat at 70° for 15 min. Cool, and decant through a Whatman No. 3 filter paper, or equivalent, into a 100-mL volumetric flask. Wash the slurry with three 10-mL portions of hot water and wash the filter paper with 15 mL of hot water, dilute to volume with water, and mix. A 3.0-mL portion of this solution meets the requirements of the Arsenic Limit Test, Appendix IBB. 

Standard Solution Prepare this solution in the same manner as the Sample Solution, but use 6.0 mL of Standard Arsenic Solution (see Arsenic Limit Test, Appendix IIIB) in place of the sample. 

Procedure Transfer 50.0 mL of the Sample Solution into the generator flask, add 2 mL of a 15 100 solution of potassium iodide, and continue as directed in the Procedure under Arsenic Limit Test, Appendix IIIB, beginning with [add] 0.5 mL of Stannous Chloride Solution, and mix.. .. Modify the Procedure by using 5.0 g of Devarda s metal in place of the 3.0 g of 20-mesh granular zinc, and maintain the temperature of the reaction mixture in the generator flask between 25° and 21°. Treat 50.0 mL each of the Standard Solution and of the Blank Solution in the same manner and under the same conditions. Determine the absorbance at 525 nm produced by each solution as directed under Procedure. 

Arsenic Determine as directed under Arsenic Limit Test, Appendix IIIB. 

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