Limit Test of Arsenic Pharmaceutical Analysis I Practical, Lab Manual, PDF
Pharmaceutical Analysis I Practical: Limit test for (1) Chloride (2) Sulphate (3) Iron (4) Arsenic Preparation and standardisation of (1) Sodium hydroxide (2) Sulphuric acid (3) Sodium thiosulfate (4) Potassium permanganate (5) Ceric ammonium sulphate Assay (1) Ammonium chloride (2) Ferrous sulphate(3) Copper sulphate (4) Calcium gluconate (5) Hydrogen peroxide (6) Sodium benzoate (7) Sodium Chloride Determination of Normality (1) Conductometric titration of strong acid against a strong base (2) Conductometric titration of strong acid and weak acid against a strong base (3) Potentiometric titration
Aim
To observe limit test for Arsenic
Principle
Limit test for Arsenic is based on the reaction of Arsenic gas with hydrogen ions to form a yellow stain on mercuric chloride paper in presence of reducing agents like potassium iodide. It is also called as Gutzeit test and requires special apparatus.
Arsenic present as arsenic acid in the sample is reduced to arsenious acid by reducing agents like potassium iodide, stannous acid, zinc, hydrochloric acid, etc.. arsenious acid is further reduced to arsine(gas) by hydrogen and reacts with mercuric chloride paper to give yellow stain on mercuric chloride paper will depend upon the quality of arsenic present in the sample.
Procedure
Label two conical flasks as Standard and Test and follow the procedure
Time needed: 1 hour
Preparation of Standard and Test solution for Arsenic Limit Test
- Prepare Standard solution
Take 1.0 ml of arsenic standard solution and dilute to 50 ml with water.
- Add potassium iodide
add 5 ml of M potassium iodide
- Add zinc AsT
add 10 g of zinc AsT
- Assemble the apparatus and immerse the flask
Immediately assemble the apparatus and immerse the flask in a water bath at a temperature such that a uniform evolution of gas is maintained
- Observation of standard solution
Observe after 40 minutes
- Test solution
Introduce the test solution
- Add potassium iodide
add 5 ml of M potassium iodide
- Add zinc AsT
add 10 g of zinc AsT
- Assemble the apparatus and immerse the flask
Immediately assemble the apparatus and immerse the flask in a water bath at a temperature such that a uniform evolution of gas is maintained
- Observation of test solution
Observe after 40 minutes
Any stain produced on the mercuric chloride paper is not more intense than that of arsenic standard solution
Synopsis Questions
Limit test of Arsenic is based on the reaction of arsenic gas with hydrogen ion to form yellow stain on mercuric chloride paper in presence of reducing agents like potassium iodide. It is also called as Gutzeit test and requires special apparatus.
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The reaction of arsenic gas with hydrogen ion in presence of reducing agents like potassium iodide.
Granulated zinc gives more surface area for the acid to act, so hydrogen is formed faster. It also prolongs the evolution of nascent nitrogen gas
Arsenic acid is reduced to arsenious acid with help of zinc
0.01 parts per million (ppm) for Drinking water
The Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit (PEL) of 10 micrograms of arsenic per cubic meter of workplace air (10 µg/m³) for 8-hour shifts and 40 hour work weeks.
10 ppm
Preparation of standard arsenic solution: Dissolved 0.330 g of arsenic trioxide in 5ml of 2 M sodium hydroxide and dilute to 250.0 ml with water. Dilute 1 volume of this solution to 100 volumes with water.
Arsenic is not likely to be detected in blood specimens drawn more than 2 days after exposure because it has become integrated into nonvascular tissues
Stannous chloride is used for the complete evolution of arsine.
Hydrochloric acid is used to make the solution acidic
Limit test for Arsenic is based on the reaction of Arsenic gas with hydrogen ions to form a yellow stain on mercuric chloride paper in presence of reducing agents like potassium iodide. It is also called as Gutzeit test and requires special apparatus
mercuric chloride paper
Multiple choice questions
- The limit test of arsenic is performed to determine the maximum allowable concentration of arsenic in a given sample. Which of the following methods is commonly used for this test?
a) Flame atomic absorption spectroscopy
b) Colorimetry
c) High-performance liquid chromatography
d) Gravimetric analysis - Which reagent is commonly used in the limit test of arsenic to form a colored complex for detection?
a) Silver nitrate
b) Sodium hydroxide
c) Hydrogen sulfide
d) Ammonium molybdate - In the limit test of arsenic, a brownish-black precipitate is formed when hydrogen sulfide gas is passed through the acidified sample solution. This precipitate indicates the presence of:
a) Arsenic
b) Lead
c) Copper
d) Zinc - Which of the following techniques is commonly used to confirm the presence of arsenic in a sample after the limit test?
a) Mass spectrometry
b) Infrared spectroscopy
c) X-ray diffraction
d) Atomic emission spectroscopy - The limit test of arsenic is based on the principle of:
a) Precipitation reactions
b) Acid-base titration
c) Oxidation-reduction reactions
d) Complex formation
Answers:
- b) Colorimetry
- d) Ammonium molybdate
- a) Arsenic
- a) Mass spectrometry
- d) Complex formation
First Year B Pharm Notes, Syllabus, Books, PDF Subjectwise/Topicwise
Suggested readings
Recommended readings:
- Definition and Scope Social Pharmacy
- Role of individual in conservation of natural resources
- Multidisciplinary nature of environmental studies
- Structure and function of ecosystem
- Research methodology mcq
- Limit test for heavy metals
- Ostwald viscometer
- Throat paint
- Limit test for arsenic
The Gutzeit test is a chemical test used to detect the presence of organic compounds, such as proteins and amino acids, in a sample. It works by adding a strong base, such as sodium hydroxide, to the sample and then measuring the amount of light absorbed at a specific wavelength. The resulting color change is used to determine the presence of specific organic compounds. The apparatus typically used for the Gutzeit test includes a spectrophotometer, cuvettes, and reagents such as sodium hydroxide solution.
The Gutzeit test is a qualitative test used to detect the presence of arsenic in a sample. It is based on the reaction between the sample and a reagent (usually a solution of mercuric nitrate and sodium hydroxide) which forms a yellow precipitate if arsenic is present. The test is a useful tool for determining the presence of arsenic in water, soil, and food samples. However, it should be noted that the Gutzeit test is not very specific and may not differentiate between different forms of arsenic, so further testing may be necessary to confirm the presence of arsenic and determine its exact form.
