m6 tuts QCQA p1

TYPES OF ANALYSIS

• Qualitative and Quantitative Analysis

• Proximate and Ultimate Analysis

• Gravimetric and Volumetric Analysis

Qualitative analysis

Determines what is present in the sample (identity and composition)

Quantitative analysis

Measures the amount (% content) of the component present in a given sample

Pharmaceutical analysis

• Part of quantitative analysis

• Strength, potency → % purity

Proximate analysis

• Total or general class of the plant constituents

• Example: Alkaloids, glycosides

Ultimate analysis

• Specific or single constituent

• Example: Atropine, Digoxin

Types of analysis: Sample size

• Ultra microanalysis

  • < 1 mg

• Microanalysis

  • 1-10 mg

• Semi microanalysis

  • 10-100 mg

• Macroanalysis

  • > 100 mg

Gravimetric analysis

• Analysis wherein the constituents of a sample are separated and then the product is weighed

• Example: Analysis of Cl in NaCl, precipitated as AgCl (using AgNO3)

Gravimetric analysis

Method of separation:

• Physical Method

  • Extraction

  • Volatilization

• Chemical Method

  • Precipitation

  • Ignition

A. 1, 3 and 4

The official USP gravimetric methods are:

1. Assay involving direct ignition

2. Assay involving sublimation X

3. Assay involving extraction

4. Assay involving precipitation followed by ignition

A. 1, 3 and 4

B. 2, 3 and 4

C. 1, 2 and 4

D. 1, 2 and 3

Volumetric analysis

• Also known as titration

• Analysis wherein a solution of known concentration (titrant) is used to determine the concentration of an unknown solution (titrand/analyte/sample)

• Example: Analysis of acids and bases

b. Proximate

Which of the following assays will involve total alkaloidal determination?

a. Specific

b. Proximate

c. Extraction

d. Ultimate

b. Gravimetric method

What assay method is illustrated in the assay of sodium chloride tablets wherein the salt precipitated is silver chloride, filtered, dried and residue is weighed?

a. Volumetric method

b. Gravimetric method

c. Complexation method

d. Redox method

b. Ultimate assay

Assay of Atropine in Belladona is an example of which of the following?

a. Biological method

b. Ultimate assay

c. Proximate assay

d. Special method

c. Gravimetric analysis

Which of the following terms is used for method of analysis done by separation of the constituent from the sample then consequently weighing the product?

a. Special method

b. Volumetric analysis

c. Gravimetric analysis

d. Gasometric

a. Quantitative method

Which type of chemical analysis measures percentage content of the component present in a sample?

a. Quantitative method

b. Qualitative method

c. Proximate method

d. Gravimetric method

CONCENTRATION EXPRESSIONS

• Molarity (M)

  • Number of moles of solute per liter of solution

  • Formula: M = moles of solute / liter of solution

• Normality (N)

  • Number of gram or mole equivalent weights of solute per liter of solution

  • Formula: N = gram equivalent wt / liter of solution

• Molality (m)

  • Number of moles of solute per kilogram of solvent

  • Formula: m = moles of solute / kg of solvent

Molarity (M)

• Number of moles of solute per liter of solution

• Formula: M = moles of solute / liter of solution

• M = Wt/MW/L

Normality (N)

• Number of gram or mole equivalent weights of solute per liter of solution

• Formula: N = gram equivalent wt/ liter of solution

• N = M × f

Molality (m)

• Number of moles of solute per kilogram of solvent

• Formula: m = moles of solute / kg of solvent

Sulfuric acid

One twentieth molar solution of sulfuric acid is 0.05 M

• 1/20 = 0.05 N

• H2SO4 = 2 H

• N = 0.05 M × 2 = 0.1 N

Valence

Analyte	Valence	Example
Acid	Replaceable H⁺	HCl (f = 1) ; H₂SO₄ (f = 2)
Base	Replaceable OH⁻	NaOH (f = 1) ; Mg(OH)₂ (f = 2)
Redox ViLEORA VdGEROA	Oxidizing agent: Electrons gained Reducing agent: Electrons lost	MnO₄⁻ → Mn²⁺ (5e⁻ gained) +7 → +2

KMnO4 / Potassium Permanganate

It is an oxidizing agent (gain 5 electrons) from +7 to +2 = Valence decreased

• VdGEROA

  • Valence decrease

  • Gain of electrons

  • Reduction reaction

  • Oxidizing Agent

True

Valence is important in Eq or mEq calculations

Eq or GEW

= MW / factor

mEq

= MW / f × 1000

b. 1N H2SO4

If the gram molecular weight of sulfuric acid is 98. Which of the following will be used to label the container of a solution containing 49 grams per liter of solution?

a. 0.5N H2SO4

b. 1N H2SO4

c. 1M H2SO4

d. 0.2M H2SO4

---

M = wt/MW/L of solution

• M = 49g / 98g/mol / 1L

• M = 0.5 M

N = M × f

• H2SO4 = 2 factors

• 0.5 M × 2

• 1 N

a. 20.15

Compute for the gram equivalent weight of MgO (MW = 40.30).

a. 20.15

b. 0.0403

c. 0.403

d. 0.2015

---

Salts depends on the positive cation / metals

• MgO - Mg is the metal

• Mg is in group 2 in periodic table → f = 2

• Eq Wt. = MW / f

• Eq Wt. = 40.30 / 2

• Eq. Wt. = 20.15

Normality

A concentration expression referring to the number of equivalents of of solute per liter of solution is

Electron lost

To find the milliequivalent factor of reducing agent, divide its molecular weight by ___ (ViLEORA)

Electron gained

To find the mEq factor of an oxidizing agent, divide the molecular weight by ____ (VdGEROA)

Eq = 31.61

The gram equivalent weight of potassium permanganate (MW = 158.03) is

• 5 electrons gained = factor

• Eq = MW/f

• Eq = 158.03 / 5

• Eq = 31.61

TITRATION

• Volumetric Analysis or Titrimetric Analysis

• To know if the equivalent amounts of reactants have reacted together

TITRATION

Set-up

• Titrant

  • Solution of known concentration and volume

• Analyte (titrand)

  • Solution of unknown concentration, but known volume

• Indicator

  • Substance that changes color indicating the endpoint

Titrant

Solution of known concentration and volume

• Must undergo standardization

• Standard solution: Volumetric Flask

• Biuret

Primary Standard

• Solid

• Substance of known purity

• Potassium Biphthalate (KBP)

• Na Oxalate

• Wt = mL × N × mEq / (mL) (mEq)

• mEq = MW / f × 1000

Secondary standard

• Liquid

• Standard solution of known concentration

• C1V1 = C2V2

• N1V1 = N2V2

True

• Mohr Biuret – base, rubberized.

• Geissler Biuret – acid, glass.

Primary Standard

Titration Type	Primary Standard
Permanganometry	Sodium oxalate (Na₂C₂O₄) f = 1
Iodimetry	Sodium thiosulfate (Na₂S₂O₃) f = 1
Cerimetry	Arsenic trioxide (As₂O₃) Sodium oxalate
Volumetric Precipitation	Sodium chloride (NaCl)
Complexometry	Calcium carbonate (CaCO₃)
Karl Fischer Titration (Water content determination)	Sodium tartrate (Na₂C₄H₄O₆·2H₂O)

Sodium oxalate or Oxalic acid

What removes potassium permanganate stain

Sodium Thiosulfate

What removes iodine stain

Analyte (titrand)

Solution of unknown concentration, but known volume

• Substance being analyzed

• In the flask

Indicator

• Substance that changes color indicating the endpoint

• Mixed indicators: SHARP endpoint point

Purpose of titration:

• Know the concentration of analyte

• Know the percentage purity of the analyte

Equivalence point

• Stoichiometric or Theoretical point

• Equivalent amounts of the Titrant and Analyte have reacted

• Non-observable

Endpoint

• Approximates the the equivalence point

• Observable (+indicator)

A. End point - approximation

The terms used when equivalent amounts of each reactant have reacted are the following, except:

A. End point

B. Equivalence point

C. Stoichiometric point

D. Theoretical point

Wash bottle

Wash down drops of standard solution clinging to the tip of the burette

Sodium chromate in H2SO4

Best for cleaning glass apparatus:

Direct titration

• One titrant

• % Purity = (mL × N × mEq / wt) × 100

  • mL and N = titrant

  • mEq Nd wt = analyte

  • mEq = MW / f × 1000

Residual titration

Back Titration

• known volume of a reagent is added in excess to the analyte

• 2 titrants

• Titrant 1 is has more reagent than titrant 2

• % Purity = [(mL × N) - (mL × N) × mEq / wt] × 100

Blank titration

do the whole titration without the analyte, titrand, sample

Titer

• g or mg of analyte that is chemically equivalent to 1 mL of the titrant

• Significance: When given, no need to calculate the mEq

Titer

When titer value is given

• % Purity = [(mL × N × mEq / wt) ÷ N titer] × 100

---

Q: Each mL of titrant is chemically equiv. to ___ mg of analyte

Wt: 1 mL × N × mEq

True

In the assay of ZnO (MW = 81.38), each mL of 1N of H2SO4, is equivalent to _ of ZnO.

• Titer = 1mL × N × mEq

• mEq = MW/f × 1000

  • Since ZnO → salt → f = 2

• mEq = 81.38 / 2000 = 0.04069

• Titer = 1mL × 1N × 0.04069

• Titer = 0.04069 g or 40.69 mg

True

This is the weight of the substance chemically equivalent to 1 mL of the standard solution: TITER VALUE

a. 97.2%

A sample of Chlorpheniramine maleate weighing 0.502 g was assayed by nonaqueous titrimetry using 22.2 mL of perchloric acid with normality of 0.1125. Calculate the % purity of the sample. Each mL of 0.1 N perchloric acid is equivalent to 19.54 mg of C16H19ClN2 · C4H4O4

a. 97.2%

b. 72.9%

c. 27.9%

d. 9.72%

---

• %P = [(mL × Nactual × titer / wt) ÷ Ntiter]

• %P = (22.2mL × 0.1125 N × 19.54mg / 502mg) = 0.0972

• %P = (0.0972 ÷ 0.1N) × 100

• %P = 97.21%

Neutralization

Acid-base titration

Acidimetry

• Titrant = Acid

• Analyte = Base

• f = number of replaceable OH-

Alkalimetry

• Titrant = Base

• Analyte = Acid

• f = number of replaceable H+

Strong Acid vs. Strong Base

• Titrant: Strong Acid (SA)

• Analyte: Strong Base (SB)

• Indicator:

  • Methyl Red (MR)

  • Methyl Orange (MO)

  • Phenolphthalein (PhP)

Phenolphthalein

• Base: Color Pink

• Acid: Colorless

Strong Acid vs. Weak Base

• Titrant: Strong Acid (SA)

• Analyte: Weak Base (WB)

• Indicator: Methyl Red (MR)

Strong Base vs. Weak Acid

• Titrant: Strong Base (SB)

• Analyte: Weak Acid (WA)

• Indicator: Phenolphthalein (PhP)

Weak Acid vs. Weak Base

• Titrant: Weak Acid (WA)

• Analyte: Weak Base (WB)

• Indicator: No indicator (no sharp endpoint)

True

Examples: ANALYTE/SAMPLE

1. ASA = Acid

   • RESIDUAL ALKALIMETRY

2. Caffeine = Base

   • DIRECT ACIDIMETRY

3. NaK tartrate = Base

   • RESIDUAL ACIDIMETRY

4. MOM = Base

   • RESIDUAL ACIDIMETRY

5. ZnO = Base

   • RESIDUAL ACIDIMETRY

---

ASA + NaK tartrate + MOM + ZnO → RESIDUAL ACIDIMETRY (ASAn ang aNAK at ZNO ang MOM)

Methyl red

When a strong acid is titrated against a weak base, the indicator is

Phenolphthalein

The indicator used in the assay of a weak acid reacting with a strong base is

True

Analyte	Titration Type
NaOH (Base)	Acidimetry (Direct)
HCl (Acid)	Alkalimetry (Direct)
ZnO (Base)	Acidimetry / Residual (often called “Back Titration”)

ACIDIMETRY

Measurement of base requires

A) Acidimetry

The measurement of a weak base in nonaqueous medium of a given sample by titration with standard perchloric acid.

A) Acidimetry

B) Alkalimetry

C) Compleximetry

D) Redox titration

Complexiometry

• Metal ion binds to ligand= COMPLEX

• Metal ion + Ligand

• Metal ion:

  • Multivalent

• Ligand:

  • 1 - unidentate

  • >1 - polydentate

• Aka EDTA titration

Ring-like structure

Metal ion + polydentate = CHELATE

Complexiometry

• Titrant: Ethylenediaminetetraacetic acid (EDTA - hexadentate ligand)

• Analyte: metals (Zn²⁺,Ca²⁺, Mg²⁺, Al³⁺, Bi³⁺)

  • Zn²⁺, Ca²⁺, Mg²⁺ - measured via DIRECT Complexiometry

  • Al³⁺, Bi³⁺ - measured via RESIDUAL Complexiometry

• Indicators:

  • Hydroxynaphthol blue

  • Eriochrome black T

Ethylenediaminetetraacetic acid (EDTA)

Complexiometry Titrant: - hexadentate ligand

Metals

Complexiometry Analyte: ___ (Zn²⁺,Ca²⁺, Mg²⁺, Al³⁺, Bi³⁺)

DIRECT Complexiometry

• Zn²⁺, Ca²⁺, Mg²⁺ - measured via ___

RESIDUAL Complexiometry

Al³⁺, Bi³⁺ - measured via ____

Hydroxynaphthol blue, Eriochrome black T

Indicators of Complexiometry

Intense color like red

Complexiometry endpoint

Masking agent

Substances that form stable complexes with interfering metal ions, preventing them from reacting with the titrant (usually EDTA) and thus improving analytical selectivity.

• Forms a highly stable complex with the unwanted metal ion.

• “Undesired metal”

Unmasking agent

This is done by adding an agent that forms even more stable complexes with the masking agent or by altering the complex's stability, allowing the metal ion to participate in the titration.

• “Desired metal”

Triethanolamine

Masks aluminum, iron, and manganese

Aluminum and Bismuth

Residual titration method under EDTA titrations is applied to metal ion:

True

The titrant most commonly used for direct compleximetry titration is EDTA (hexadentate)

Precipitimetry or Volumetric Precipitation

Aka ARGENTOMETRIC TITRATION

Formation of insoluble substances to cause the reaction

• Gay Lussac

  • Titrant: Silver nitrate

  • No indicator

  • Analyte: NaCl (Cl-)

  • Endpoint: Cessation of ppt

• Liebig

  • Titrant: Silver nitrate

  • No indicator

  • Analyte: Cyanide

  • Endpoint: Formation of turbidity

• Volhard

• Mohr

• Fajans

Volhard

• Titrant:

  • AgNO₃ and NH₄SCN (Silver nitrate and Ammonium thiocyanate)

• Indicator:

  • Ferric ammonium sulfate (FAS) / Ferric alum

• Analyte:

  • NaCl

  • Aminophylline

• Note: (+) Nitrobenzene to achieve sharp and accurate endpoint

AgNO₃ and NH₄SCN (Silver nitrate and Ammonium thiocyanate)

Titrant for Volhard:

Ferric ammonium sulfate (FAS) / Ferric alum

Indicator for Volhard

NaCl, Aminophylline

Analyte in Volhard

Nitrobenzene

Add ____ in Volhard Method to achieve sharp and accurate endpoint

Insoluble colored complex (ppt)

Endpoint of Volhard Method

Mohr

• Titrant:

  • AgNO₃ (Silver nitrate)

• Indicator:

  • K₂CrO₄ (Potassium chromate)

• Analyte:

  • SLS (Sodium Lauryl Sulfate)

• Endpoint:

  • Secondary precipitate (Red)

AgNO₃ (Silver nitrate)

Titrant for Mohr Method

K₂CrO₄ (Potassium chromate)

Indicator for Mohr Method

SLS (Sodium Lauryl Sulfate)

Analyte in Mohr Method

Secondary precipitate (Red)

Endpoint for Mohr Method

Fajans

• Indicators: Adsorption indicators (dyes)

  • DCF = dichlorofluorescein

  • TEE = tetrabromophenolphthalein ethyl ester

  • Eosin Y

• Titrant:

  • AgNO₃ (Silver nitrate)

• Analyte:

  • KCl (Potassium chloride)

  • iopanoic acid

  • Cl- (chlorides

Adsorption indicators (dyes)

Indicators for Fajans Method

Adsorption indicators (dyes)

• DCF = dichlorofluorescein

• TEE = tetrabromophenolphthalein ethyl ester

• Eosin Y