Pharmaceutical analysis-1- Gravimetric analysis

-

☞Gravimetric analysis☜

Principle and basic Steps-; 

★ Gravimetric analysis is based on conversion of ions , or elements into a pure & stable compound after a precipitation reaction.

★ Formed precipitation can be directly weighed & quantity.

Example-; 

BaClշ    +     HշSo４     →      BaSo４    +   2HCl
Analyte.      Precipitating.     Precipitate
                         Agent
★ Analyte solution will be taken.
★ Analyte will be precipitated by using suitable precipitation agent.
★ Precipitate will be pure & stable compound.
★ Precipitated compound will be filtered, dried & weighed.

% of analyte= wt of precipitate × gravimetric factor × 100 / wt. Of sample

Gravimetric factor = atomic mass of Ba๋ ๋๋ /atomic mass of BaSO4

Limitations of precipitation-;

★ Precipitated compound must be converted in pure.
★ Precipitated compound must be free from impurities.
★ precipitated compound must be insoluble in the solution.
★ Precipitated compound must be easily filtered by simple filtration techniques.

Co- precipitation-;

★ When more than one compound or substance get precipitated in the solution called co- precipitation.
★ Co- precipitation is causing problem in gravimetric analysis.
★ It can interfere with original precipitate.

Co- precipitation overcome by-;

1. Digestion
2. Dissolving to precipitate & reprecipitation.

Mechanism of co- precipitation-;

Inclusion — 



Occlusion— 


Methodology or steps involved in gravimetric analysis-;

1. Preparation of sample solution
2. Precipitation
3. Digestion
4. Filtration & washing 
5. Drying or ignition
6. Calculation

1. Preparation of sample solution-;

★ Sample is prepared by dissolving in suitable.
★ Adjust the volume, pH of solution.

2. Precipitation-;

★ Precipitating agent will be added in the prepared sample solution.
★ After addition of precipitating agent nucleation or precipitate formation starts.


3. Digestion-;

★ The ppt. Is left hot for 30 - 60 minute in order to digest small Particles.
★ During digestion small particles get dissolved & reprecipitate after cooling ( Ostwald's ripening).

4. Filtration & washing -;

★ Take filter paper & filter the supernatant liquid precipitate. 
★ After filtration washing is due by hot water .
★ Impurities will be removed by washing.

5. Drying & Ignition-;

★ After drying or ignition, we can get exactly between structure of the analyte.
★ Filter paper 1 & 41 known as ashless.

6. Calculation-;

   BaClշ    +    HշSO４  →    BaSO４     +  2HCl 


% of anlyte = wt. Of ppt × gravimetric factor× 100/ wt. Of  sample

Post precipitation-; 

★ Analyte ion will precipitate out first due to ppt agent.
★ After that other ion are precipitated by same ppt agents. 
★ Precipitation of these ions called post ppt.
★ Rate of reaction is slower in post ppt & it is occurs during digestion.
★ It gives always impurities.

Estimation of BaSO4 -;

Preparation of sample & reagent-;

Sample preparation ⇒ 20.8 gm of BaCl շ⇒ Dissolved in 1 ltr. Distilled water.

Preparation of dilute HշSO4-;
  
Dissolve 3ml concentration HշSO4 ⇒100ml distilled water
BaClշ + HշSO4   ⇒ BaSO4   +   2HCl

Methodology-;

            Pipette out 25 ml BaClշ in beakar
                                        ⇓
Add 0.5 ml HշSO4& make up volume upto 100ml
                                        ⇓
                 Heat solution till boiling
                                        ⇓
     HշSO4 add dropwise with stirring
                                        ⇓
      Ppt formation start & allow the ppt settled                                       down 
                                        ⇓
  Filter the ppt through filter paper & washed                           with water 
                                        ⇓
Ignite the ppt in hot air oven after drying
                                       ⇓
                 Weigh the ppt sample 
                                       ⇓
     Calculate the % of analyte by formula

Instrumentation of potentiometric titration-;

Various parts of potentiometric—

1. Electrode;
a. Reference electrode
• standard hydrogen electrode
• calonel electrode
• AgշCl electrode

b. Indicator Electrode
• metal electrode
• glass

2. Titration vessels-; It is used to hold the sample.
3. Titration burette-; Hold the titrant.
4. Magnetic stirrer-;  Help to mix / stir the solution present in vessels.

HCl  + NaOH        →         NaCl      +   HշO


Working-;

★ It involves the measurements of potential of an indicator Electrode with respect to reference electrode. We start adding titrant in small quantity, potential difference created & potentiometer record the cell potential.

Potentiometric titration-; 

★ It is the method of find out the concentration of solute in a given solution by measuring potential between two electrode.

★ This method gives more accurate method of determination.
★ In this method two types of Electrode are used— 
1. Reference electrode.
2.standard electrode
★ In this method of Titrations no indicator reagent used.
★ Instead of indicators reagent indicator Electrode is used.

Principle-;

★ When a pair of Electrode placed in sample solution it's shows the potential difference by addition of titrant, by changing the concentration of ions. 

Types of potentiometric titration-;

1. Acid base titration
2. Redox titration
3. Complexometric titration
4 . Precipitation titration

    

                          Thankyou











Comments

Post a Comment

Popular posts from this blog

Pharmaceutical engineering || Manometer

-
Image
        ★ Manometer★ • It is a device of instrument which is Used to measure pressure difference. Types of manometer- 1. Simple manometer a. U tube manometer b. Piezometer c. Single column manometer 2. Differential manometer a. U tube differential manometer b. Inverted U-tube differential manometer Simple manometer-; Simple manometer are made up glass tubes one end of those remain open to the atmosphere and the other hand are collected to the point were pressure to be measure. Principle-; • It were one of the principle of hydrostatic equilibrium and is used for measuring pressure ( static pressure). • Exceded by a stil liquid or gas hydrostatic equilibrium state that the pressure at any point in a fluid at rest is equal and it's value is just the weight of the over living Fluids. • The manometer is the simplest instrument for gauge pressure low range pressure instrument alaning the pressure against the weight of a coloum In liquid. • The action of are manometer depen...
Read more

B.pharma 1st semester Notes pharmaceutical analysis unit - 4th- Redox Titrations

-
Image
          //  Redox Titrations \\ • A Redox titration is a type of titration in which titrant and titrand react through and oxidation reduction reaction. • The end point of a Redox titration is detected by using indicators. Principles of Redox titration; Reduction—  • The subtances  can undergo reduction by followin. • The addition of hydrogen. •The removal of oxygen. • The acceptance of electrons. Example- fe³+→fe ²+  Oxidation— • Addition of oxygen. • Removal of hydrogen. • Loss/ donation of electrons. Example- fe²+ → fe³+ Oxidising agents;  •An oxidising agent is a chemical species that causes that other reactant in a redox reaction to be oxidized, and it is always reduced in the process. Example- Ag + , O², O³
Read more

Diabetes mellitus short notes -

-
               ;Diabetes mellitus; • Carbohydrate body turns it into a sugar called glucose and sends that to your bloodstream. • pancreas release insuline  Type 1 diabetes; • It's an autoimmune disease. • 10 % of people who have diabetes have type 1. • It was once better known as" Juvenile" diabetes • It is also called insulin dependent diabetes. Type 2 diabetes; • 95% of people have type 2 diabetes.   Symptoms of diabetes; • Increase thirst  • Weak, tired feeling. • Blurred vision . • Number or tingling in the hand or feet. • slow - healing sores or cuts. • unplanned weight loss. • Frequent urination. • Frequent unexplained infection. • Dry mouth  Treatment; • Diuretic • Drugs that ↑ insulin production. • Drugs that ↑ sugar absorption. • Nutritional & meal time. • Exercise, reduced stress. • Quit smoke& alcohol.
Read more