Pharmaceutical Analysis &Errors

Pharmaceutical Analysis (BP102T)
UNIT I
Pharmaceutical Analysis &Errors

UNIT-I
 Pharmaceutical analysis-
 Definition and scope
 Different techniques of analysis
 Methods of expressing concentration
 Primary and secondary standards.
 Preparation and standardization of various molar and normal solutions
Oxalic acid, sodium hydroxide, hydrochloric acid, sodium thiosulphate,
sulphuric acid, potassium permanganate and ceric ammonium sulphate
 Errors :Sources of errors, types of errors, methods of minimizing errors,
accuracy, precision and significant figures

Definition
 Pharmaceutical Analysis is a branch of analytical chemistry which deals with
methods for identification, quantitation and purification of a sample
 Scope-
 the scope of analysis very vast because almost all Industries required both
qualitative as well as quantitative method of analysis for analysing their raw
material ,finished product ,intermediate ,packing material .
 Identification of active pharmaceutical ingredients
 Analyzing purity of active pharmaceutical ingredients.
 Determination of stability of drug and its formulation
 Determination of efficacy of a drug
 Study of drug release mechanism
 Mixture analysis.

 Apart from these pharmaceutical applications an analytical method finds it use
in almost all other fields also,
 Laboratory diagnostic studies in the testing of biological fluids like blood and
plasma.
 Soil studies to identification and estimation of mineral in the soil
 Forensic studies to investigate sample
 Diary product studies to estimation the milk product like better, cheese, ghee
etc
 Purification and analysis of water under environmental studies.
 Determination of different types of ingredients like preservative

Different techniques of analysis
 FAQ-
 Explain different techniques of analysis. (IMP)
 Describe briefly various techniques used in pharmaceutical analysis.
 Difference between qualitative & quantitative analysis.
 Difference between volumetric & gravimetric analysis.
 Analytical techniques categorized based on types of method & based on nature
of techniques as follows.
 A) Based on types of method
 Can be broadly classified into two types:
 1) Qualitative Analysis
 2) Quantitative Analysis
 1) Qualitative Analysis: this is the types of analysis which states about
presence or absence of the desired components in the given sample.
 To detect the presence or absence of analyte in the given sample result in one
of the following observation like colour change, evaluation of gas, formation of
precipitation, melting point, refractive index, optical activity.

 2) Quantitative Analysis:
 this is the types of analysis which states about quantify of the desired components
in the given sample.
 This measurement of volume of solution, measurement of absorbance, pH
change, optical rotation, potential, currant voltage etc to get numerical value for
stating the quantity of analyte.
Qualitative Analysis Quantitative Analysis
It is a subjective method of analysis It is objective method of analysis
This method of analysis focuses on
non-numerical data that cannot be
computed.
This method of analysis includes
statistical data
The sample size needed for this type of
analysis is small.
The sample size needed for this type of
analysis is large.
This method answers the concept
whether present or absent.
This method answers in term of how
much & how many.
The data in this type of analysis is in
term of words, objects ,pictures,
observations and symbols
The data in this type of analysis is in
terms of numbers and statistics.

 Based on nature
 Another way of classifying analysis is based upon its nature is as follows:
 1) Chemical methods
 2) Electrochemical methods
 3) Instrumental Methods
 4) Biological Methods
 1) Chemical Methods :
 A) Volumetric (Titrimetric) Methods:
 As the name ‘volu’ refers for volume and ‘metric’ refers for measurements i.e
this is method in which volume will be measured.
 This methods involves two or more reactants which react with each other and
gives the end point of the reaction with help of an indicator which will give a
visible change that could be noticed

 a) Acid base titration :
 i) Aqueous Acid base titration ( Neutralization reactions):
 Acid base titration depends on the neutralization reaction between an acid and a
base when mixed in solution, in addition to the sample, an appropriate indicator
must be used for reflecting the change in colour solution or pH value of solution
after reaction is completed at the end point.
 Acid base titration is used for analysis of substances which are acidic or basic in
nature.
 ii) Non-aqueous Acid base titration:
 As the name itself, in this method water is not used as solvent instead non-
aqueous solvents like perchloric acid, glacial acetic acid is used for titration.
 b) Precipitation Titrations:
 In this titration halide ions ( Chloride, Bromide, Fluoride, Iodide ) are
determined by titrating with standard solution of silver nitrate, in which by
reaction silver halide precipitate is formed,

 c) Complexometric titration :
 Complexometric titration is titration between metal ions and chelating agents,
most commonly used ions and Chelating agents, most commonly used chelating
agents is disodium EDTA solution because it is versatile and it almost from
complex with all metal
 d) Oxidation reduction titration :
 Redox titration is oxidation reduction type of titration in which oxidizing agents
and reducing agents react together and gives oxidation and reduction reaction
simultaneously.
 Definition and commonly used terms in volumetric analysis:
 Standard Solution : the solution of accurately known concentration is termed
as standard solution.
 Titrate: the substance or sample being titrated is termed as Titrate
 Titrant: the standard solution of known concentration is termed as Titrant
 Equivalence point: the point at which the reaction between titrant and titrate is
just complete is termed as equivalence point.
 End Point: after the equivalence point when an excess amount of titrant is
added to the sample solution, it gives some colur change due to presence of
indicator in it, this is referred as end point of titration
 Indicator: it is an auxiliary substance which show visual colour change after the
reaction between titrate and titrant is practically complete.

 2) Gravimetric Methods
 Gravimetric method refers to measurement of weight of residues after
converting the sample into an insoluble from ( precipitate) of final composition
which cannot be further altered.
 This method was further development by combing with the use of electrodes and
standard substance.
 The method include thermogravimetry (TG) which records the change in weight,
differential thermal analysis (DTA) which records the difference in temperature
between test substance and inert reference material, differential Scanning
Calorimeter (DSC) which records the energy needed to establish a zero temp.
Gravimetric Analysis Volumetric Analysis
Gravimetric analysis is a method in which
mass of analyte is measured.
Volumetric analysis is a method in which
volume of analyte is measured
The final result in this method are expressed
in grams.
The final result in this method are expresses in
mL
This method involves formation of an
insoluble solid mass known as precipitate,
which can then be separated from Solution
This method involves titration of analyte with
a solution of known concentration.
e.g. assay of piperazine citrate, barium
sulphate
E,g Assay of soium chloride, boric acid

 3) Gasometrical Analysis:
 Geometry involves measurement of the volume of gas evolved or absorbed in a
chemical reaction.
 These method are typically used in determining the purity of inhalant gases
used in medicine.
 B) Electrochemical Methods:
 Electrochemical methods of analysis involves the measurement of electric
current, voltage or conductance in relation to the concentration of sample in the
solution.
 The various electrochemical methods a) Potentiometry
 B) Conductometry
 C) Voltametery
 D) Paleography
 E) Amperometry
 Potentiometry measures electrical potential of an electrode in equilibrium with
an ion to be determined.
 Conductometry measures electrical conductivity of an electrode with a
reference electrode while polarography, Voltametry and amperometry measures
electrical current or volatage at electrode.

 C) Instrumental Method of Analysis :
 1) Spectroscopic methods 2) Chromatographic methods
 These methods deal with the instrument of specific properties of a compound or
sample
 These method are proved to be more sensitive methods as compared with other
methods as these methods are capable of detecting the sample in microgram to
nanogram quantities also
 The specific properties which are measured in instrumental methods include
refractive index, partition coefficient, optical rotation, absorbance
 The techniques which are based on spectroscopic measurement include Atomic
absorption Spectroscopy, Atomic emission, UV visible Spectroscopy, Infrared
Spectroscopy, Raman Spectroscopy, Fluorimetry, Nuclear Magnetic Resonance
Spectroscopy.
 The various Chromatography method include Paper Chromatography, thin layer
Chromatography (TLC), High performance thin layer Chromatography (HPTLC),
High performance Liquid Chromatography ( HPLC), Gas Chromatography (GC)

 D) Biological Methods:
 For determining the efficacy or potency of a drug one need to go for the
biological method of analysis which is referred as bioassays.
 These biological methods may be carried out either by in vivo or in vitro
method.

Method of Expressing Concentration
 FAQ
 Define various methods of expressing concentration.
 Explain the term molecular weight & Equivalent weight.
 Difference between Molarity and Normality.
 Explain the term Molarity, Normality And Molality.
 Define various methods of expressing Concentration.
 Write short note on Normality And Molarity
 In the quantitative analysis method, expression of concentration of solution is
required.
 To express concentration of solution one need to known the weight and volume
of solute and solvent respectively.
 1) Chemical Method of expressing Conc.
 2) percent Conc.

 1) Chemical Method of expressing Concentration
 1) Molecular weight: Calculate as the sum of the atomic weights of the constituent
atoms
 2) Equivalent weight: the mass of a substance especially in grams that combine with
or is chemically equivalent to eight grams of oxygen or one gram of hydrogen the
atomic or molecular weight divided by the valence.
 3) Mole: the mole is the unit of measurement for amount of substance in the
international system of units , 1 mole = 6.02214076 X 1023
 4) Normality: Normality is defined as number of gram equivalents of a solute in one
liter of solution.
 It is represent as ‘N’ and expressed by formula,
 N= No. of gram equivalent of solute / volume of solution in liter
 5) Molarity: Molarity is defined as number of moles of solute in one liter of solution
 It is represent as ‘M’ and is expressed by formula
 M= No. of mole of solute / Volume of Solution in liter
 6) Molality: Molality is defined as number of moles of solute in one kilogram of
solution.
 It is represent as ‘m’ and is expressed by formula
 m=No. of mole of solute / weight of Solution in kg

 Percent Concentration:
 Concentration is often expressed in terms of percent.
 Percent concentration of a solution can be expresses as
 1)Percent by mass w/w:
% w/w = Mass of solute X 100 / Mass of solution
2) Percentage by Volume v/v
% v/v = Volume of Solute X 100 / Volume of Solution
3) Percentage by w/v
% w/v = Mass of solute X 100 / Volume of solution
percentage w/w is frequently used to express the concentration of commercial aqueous
reagent, percent v/v is used to specific the concentration of a solution prepared by
diluting a pure liquid with another liquid and percent w/v is indicate the composition of
dilute aqueous solution of solid reagents.
4) Parts per Million:
Parts per million is frequently used to express the concentration of very dilute solution
and is expressed as ‘ppm’
Cppm = Mass of solute X 106 / Mass of solution
5) Parts per Billion:
For even more dilute solutions concentration is expresses in parts per billion and is
expressed as ‘ppb’
Cppb = Mass of solute X 109 / Mass of solution

Primary and Secondary standards
 FAQ:
 Define a primary standard and give its properties.
 Write a note on primary standard. ( IMP)
 Define a primary standard. Enlist requirement of primary standard.
 Define a primary standard. Why KMnO4 cannot be used as primary standard.
 Define a primary standard with examples.
 1) Primary standard solution :
 Defn: the substance of high purity used in preparation of standard solution are
known as primary standard.
 Primary standard is typically a reagent which is high purity, stability and which
can be weighted easily.
 Primary standard solution is a solution which is used to determine the
concentration of another solution.
 Primary standard is a reagent which is available in purest from
 preparation of standard solution:
 For preparation of standard solution, reagents of high purity and stability are used.

 For standard solution the accurate weight of reagent is taken, dissolved and dilute
to exact known volume of solvent and concentration is calculated on theoretical
basis.
 Primary standard substance should satisfy the following requirement ( Ideal
Properties of primary Standard )
 1) it should be 100 % pure although 0.01 to 0.02% impurity can be tolerated if
accurately known.
 2) it must be easy to obtain, easy to purify and to preserve in the purest form.
 3) it must be stable to atmospheric conditions. It should not get decompose or
should not be hygroscopic.
 4) it should have a high equivalent weight so as reduce the weighing errors.
 5) the reaction with the solution should be instantaneous and stoichometric.
 6) the reaction of standard must be such that it will allow the use of indicator to
determine the end point of titration.
 7) there should not be any titration error.
 8) the substance should be soluble under the condition of titration.
 9) it should not contain any water for crystallization, so that the chemical
composition of substance will remain same till its shelf life.

 Following are the few example of primary standard substance used in different
types of titration :
 Aqueous acid base titration : Potassium hydrogen phthalate, sodium carbonate,
succinic acid.
 Non- Aqueous acid base titration : Potassium hydrogen phthalate, epherdrine
hydrochloride.
 Precipitation titration : potassium chloride, sodium chloride, potassium bromide .
 Complexometric Titration : Zinc metal, Calcium Carbonate, Calcium gluconate,
lead nitrate.
 Redox titration : Oxalic acid, potassium bromate, potassium iodate, arsenic
trioxide, sodium oxalate.
 KMnO4 is not used as primary standard because it is difficult to obtain pure state of
KMnO4 as it is not free from MnO2. also , the colour is so intense that it acts as
self indicator.

 Secondary standard solution :
 A secondary standard substance is a reagent whose active content are estimated by
comparison with primary standard substance.
 As the number of primary substances are limited, a substance with less purity is
used in titration to react with the standards substance. Such substance are known
as secondary standard.
 A secondary standard is a chemical or reagent which has certain properties such as
follows.
 It has less purity than primary standard.
 Less stable and more reactive than primary standard but its solution remains stable
for a long time.
 Titrated against primary standard .
 Following are the example of secondary standard substance in different type of
titration :
 Aqueous acid base titration : Sodium Hydroxide, Hydrochloric acid, Sulphuric
acid
 Non- Aqueous acid base titration : Perchloric acid, lithium methoxide.
 Precipitation titration : Silver nitrate, ammounim thiocyanate.
 Complexometric Titration : Disodium EDTA
 Redox titration : Potassium permangante, sodium thiosulphate, iodine, potassium
dichromate.

Preparation and standardization of various
molar and normal solution
 As per the definition of molarity, when the compound equal to its molecular
weight is weighed dissolved in sufficient quantity of water and finally volume is
made up to one liter this will give unit molar solution.
 Similarly, as per the definition of normality, when the compound equal to its
equivalent weight is weighed dissolved in sufficient quantity of water and finally
volume is made up o one liter this will give unit normal solution.
 In general for standardization of any secondary compound , it need to be titrated
compulsorily with a primary standard in the presence of suitable indicator.

Preparation and standardization of
Sodium hydroxide
 FAQ:
 How do you standardize 0.1M Sodium Hydroxide solution ?
 Discuss the preparation and standardization of 0.1 m sodium hydroxide solution.
 Describe preparation and standardization of 0.1 N sodium hydroxide solution.
 Principle: standardization of sodium hydroxide is based on acid-base type of
titration where indicator used is phenolphthalein.
 Here strong base sodium hydroxide react with potassium hydrogen phthalate
which is a primary standard and there is formation of salt and water.
Phenolphalein gives the end point as colorless to pink.
 Procedure:
 1) preparation of 0.1M sodium hydroxide:
 Weigh accurately 4 gm of sodium hydroxide dissolve it in sufficient quantity of
water to produce 1000 ml of water.

 2) Standardization of 0.1M Sodium hydroxide:
 Weight accurately 0.5 gm of potassium hydrogen phthalate dissolve in 7.5 ml of
water .
 Add 2 drop of phenolphthalein as an indicator and titrate against sodium
hydroxide until permanent pink color obtained.
 Factor
 Each ml of 0.1 M NaoH is equivalent to 0.2042 gm of C8H5KO4

Preparation and standardization
Hydrochloric acid
 Principle: Standardization of Hydrochloric acid is based on acid base type of
titration where indicator used in methyl red.
 Here weak base sodium carbonate a primary standard react with HCL to form salt
& water , end point obtain yellow to pink.
 When solution carbonate is titrated with acid it results into formation of carbonic
acid which contributes to acidity of solution and therefore indicator changes color.
 1) preparation of 0.5 M Hydrochloric acid.
 Measure 42.5 ml of conc. HCl dissolves it in sufficient of water to produce 1000 ml
 2) Standardization of 0.5 M HCl
 Weight accurately 0.15 gm of anhydrous sodium carbonate, dissolve it in 10 ml of
water. Add two drops of methyl red solution and titrate against hydrochloric acid
until pink color is obtained.
 Heat the solution to boiling, cool and continues the titration if pink color changes to
yellow

Reaction:
Factor:
Each ml of 0.5 M Hcl is equivalent to 0.02649 gm of Na2CO3

 Principle: Standardization of Sodium Thiosulphate is based on redox ( iodometry) types
of titration.
 Here sodium thiosulphate act as reducing agents. It reduces liberated iodine to iodide
and itself get oxidized to sodium tetrathionate.
 The liberated iodine is then titrated with sodium thiosulphate using starch solution as an
indicator.
 The end point of titration is blue to colorless.
 1) Preparation of 0.1 M Sodium thiosulphate:
 Dissolve 25 gm of sodium thiosulpahte and 0.2 gm of sodium carbonate in carbon
dioxide free water and dilute to 1000 ml with the same solvent.
 2) Standardization of 0.1 M Sodium thiosulphate:
 Dissolve 0.2 gm potassium bromate in sufficient water to produce 250 ml
 To 50 ml of this solution, add 2 gm potassium iodide and 3 ml of 2M hydrochloric acid
and titrate with the sodium thiosulphate solution using starch solution as an indicator
which is added the end point of titration.
 Factor: each me of 0.1 m sodium thiosulphate is equivalent to 0.002784 gm of KBrO3
Preparation and standardization Sodium
Thiosulphate

 Principle: standardization of sulphuric acid is based on acid – base type of titration
Na2CO3 is a primary standard which react with strong acid. i.e Sulphuric acid and
there is formation of salt sodium sulfate and carbonic acid. Methyl red is used as
indicator which gives the end point from yellow to pink.
 Preparation of 0.5 M sulphuric acid :
 Measure 27 ml of conc. Sulphuric acid dissolve it in sufficiently quantity of water
to produce 1000 ml.
 Standardization of 0.5 M sulphuric acid :
 Weight accurately 0.15 gm of anhydrous sodium carbonate, dissolve in 10 mo of
water. Add 2 drop of methyl red solution and titrate against sulphuric acid until pink
color is obtained.
 Heating the solution to boiling , cool and continues the titration if pink colour
changes to yellow.
 Factor: each ml of 0.5 M H2SO4 is equivalent to 0.05299 gm of Na2CO3
Preparation and Standardization of
Sulphuric Acid

 Principle: standardization of Potassium permanganate is based on redox titration.
Here potassium permanganate act as oxidizing agents in presence of sulphuric acid.
Here potassium permanganate itself as an indicator which gives end point as
colorless to pink.
 Preparation of 0.02 M Potassium permanganate:
 Weight accurately about 3.2 gm of potassium permanganate, dissolve it in sufficient
quantity of water to produce 1000 ml . Prepare the solution two day before and
filter through glass wool if necessary.
 Standardization of 0.02 M Potassium permanganate:
 Wight accurately about 0.1 gm of oxalic acid dissolve it in 80 ml of water, add 5 ml
of concentrated sulphuric acid.
 Warm above solution to nearly 70 c and titrates with the potassium permanganate
solution till a permanent pink color is produced.
 Factor: each ml of 0.02 M Potassium permanganate is equivalent to 0.006302 gm
of C2H2O4
Preparation and Standardization of
Potassium Permanganate:

 Principle: standardization of ceric ammonium sulphate is based on oxidation-
reduction type of titration. Here ceric ammonium sulfate act as oxidizing agent
which oxidizes arsenous acid to arsenic acid and itself get reduced from ceric to
arsenic acid and itself get reduced from ceric to cerium.
 Preparation of 0.1 M Ceric ammonium sulphate:
 Dissolve 65 gm of ceric ammonium sulphate with heat in a mixture of 30 ml of
sulphuric acid and 500 ml of water. The mixture was cooled and filtered.
 Standardization of 0.02 M Potassium permanganate:
 Weight accurately 0.2 gm of arsenic trioxide and dissolve it in about 25 ml of 8%
solution of sodium hydroxide and add 100 ml of water.
 The above flask add 30 ml of dil. Sulphuric acid and 0.15 ml osmic acid solution,
add 0.1 ml of ferroin sulphate solution as indicator and titrate against ceric
ammonium sulphate until colour changes from pink to pale blue.
 Factor: each ml of 0.02 M ceric ammonium sulphate is equivalent to 0.00946 gm
of AS2O3
Preparation and Standardization of Ceric
ammonium sulphate:

ERRORS
 Sources of errors, types of errors, methods of minimizing errors, accuracy,
precision and significant figures
 Error is defined as the difference between the experimental mean value and a
true value.
 Errors are mainly classified as determinate and interminate.
 Determinate errors by name indicate that these can be determined and thus can
be avoided or corrected.
 Interminated errors are random errors over which analyst has no control.

 Sources of errors:
 FAQ:
 Brief account on source of errors.
 Discuss source of errors encountered during analysis.
 Error in analysis may be associated with use of instrument, equipment and changes
in laboratory equipment.
 Quality of reagents, samples and other factor affects the testing resulting in many
errors.
 Equipment manufacturing not following procedure such as standard operating
procedure ( SOP) and special instrumentations are some of the major reasons of
errors.
 It can be summarized that during physical and chemical testing, instrument
malfunction and operator error are the two major concerns of errors.

Types of Errors
 FAQ-
 Write a short note on errors in analysis.
 Classify the errors in analysis.
 Write a short note on types of errors.
 What are errors ?

Types of Errors
 It is to be understood here that perfect classification of errors is difficult.
 These errors are broadly categorized as
 1) determinate ( Systeminate)
 2) indeterminate ( random) errors.

 1) Determinate ( Systeminate)
 Determinate errors also called as systematic errors and as name suggest it can be
avoided
 It can be minimized or eliminated with proper training and experience.
 Systeminate errors are classified as follows.
 1) Absolute error:
 Absolute errors is the amount of errors in measurement and is the difference
between the measured value and true value
 Absolute errors can be easily calculated by using following formula
 For example: if any analytical balance indicates 99 mg but you know your true
weight is 100 mg, then the balance has an absolute errors of 100-99 mg = 1 mg
 2) Relative error (RE)
 relative errors is a measure of relative uncertainty of measurement when
compared to the value of the measurement
 For example: an errors of 1.5 cm would be considerable for total length of 15 cm
of an object

 3)Proportional errors:
 Proportional errors decrease and increase in proportion to the size of sample.
 E.g. if you increase amount of sample proportionally higher amount of
contaminant will be present in sample and will contribute proportionally in the
response of the method.
 4) Operational errors:
 Errors associated with the operation e.g transfer of solution, incomplete drying,
under weighting of precipitates, overweighing of precipitates.
 These errors are physical in nature and occur when proper analytical techniques
and procedure are not followed.
 5) Personal errors:
 Personal errors may result from the carelessness or personal limitation of the
analytical chemist.
 In analytical laboratory during experimentations many measurement require
personal judgment , the color of solution at the end point in a titration, the level
of a liquid with respect to a graduation in a pipette or burette.

 6)Instrumental errors:
 There are various reasons, may be limitation of devices, faulty and non-calibrated
instruments.
 7) Reagent Errors:
 Errors due to impurities present in reagent may affects magnitude of the
observation, even solvents may have interferences.
 8) Constant errors:
 Important aspect of this errors is its magnitude which essentially remains same
even if the measured value is varied.
 Another character of constant errors is that the associated when sample size
changed.
 One way of reducing the effect of constant error is to increase the sample size
until the error is acceptable.

 9) Errors due to methodology:
 Errors associated with sampling and incompleteness of a reaction
 Reagents which are not prepared, processed, stored as per SOP may be source of
errors .
 10) Additive Errors:
 Errors associated with weighing
 Loss of crucible weight during precipitation
 11) Environmental errors:
 In analytical lab various environmental factors such as temperature, humidity,
particles, light intensity etc.
 Measure should be in place to maintain the laboratory environmental parameter
in controlled condition.

 Indeterminate ( random) Errors:
 Random errors cannot be assigned to any specific reasons or cause.
 These errors are due to minute variations in several successive measurement
under same experimental setting such as experimental performance by the same
analyze, in same lab, using same experimental parameter.

Methods of Minimizing Errors
 FAQ:
 Write a short note on minimization of errors in analysis.
 Write a short note on errors in analysis.
 Explain in detail method to minimize the errors.
 Explain various method to minimize errors in pharmaceutical analysis.
 Analyst has no control on random errors but systemic errors can be reduced by
using various methods. By adopting following measures
 1) Calibration of instrument, apparatus and applying necessary correction.
 2) performing a parallel control determination and multiple determination.
 3) Blank determination
 4) Cross checking result by different methods of analysis or another analyst.
 5) method of standard addition
 6) method of internal Standard
 7) Amplification method

 1) Calibration of instrument, apparatus and applying necessary correction.
 A calibration always necessary for all the measuring device used in the analytical
laboratory and it is mandatory as per GMP.
 One more and important aspect of calibration is that result of equipments
calibration should be traceable to the national and international standards.
 Most commonly instrument used in pharmaceutical analytical laboratory such as
UV- Spectrophotometer, IR spectroscopy, electrical balance, PH meter,
turbidimeter, polarimeter, refreactometer the like must be calibrated.
 There are few equipment which need to calibrate before each use .
 Glassware such as pipette, burette, volumetric flask, and other measuring device
such as thermometer, weight balance etc must calibrate and necessary correction
applied.
 2) performing a parallel control determination and multiple determination.
 Under such condition he amount of analyst present in the sample can be obtained
by using following equation.

 3) Blank determination
 By name it involve blank determination using the reagent and solvent in same
way by excluding analyte in the procedure.
 Blank determination is very useful methodology to rule out the effect of
impurities in anlayte , interfering substance present in the reagents, solvents.
 This also gives information about an excess of standard solution required to
achieve end point during titration experiments.

 4) Cross checking result by different methods of analysis or another analyst.
 Sample is analyte by using radically different method to determine accuracy
 As an example standardization of HCL solution can be achieved by titration with
a standard NaOH solution. Radically different method such as precipitation of
chloride by using AgNO3 and weighing as AgCl can be performed to cross check
result of acid base titration.
 Alternative cross checking by another analyst may be very helpful.


 5) method of standard addition:
 When applying the concept of standard addition sample is divided into two
portions, to one portion standard is added.
 Both the sample analyzed by proposed method of analysis and result calculated .
 6) method of internal standard
 Method of internal standard is one of the easy options to overcome matrix
interference of analytical laboratories.
 This method involve adding known and increasing standard analyte to the series
of dilution of the solution.

Accuracy & Precision
 FAQ:
 Write about accuracy & precision
 Difference between accuracy & precision.
 Explain accuracy & precision.
 Write a short note on accuracy & precision.
 Accuracy & Precision in connection with scientific data are two most discussed
and are of concern.
 Accuracy is nearness to the true value and precision is related to repeatability or
reproducibility.
 The result which match very nearly with true value of the measured parameter
indicate accuracy and are called accurate result.
 Precision simply refer to the closeness of the multiple measurement to each other
and is independent accuracy.
 In scientific experiment precision is always calculated by statistical treatment of
the data.

Comparison
aspect
Accuracy Precision
Meaning Accuracy refers to the degree of
conformity and correctness of
observation when compared to a
true or absolute value.
Precision implies the level of
variation
Measurement Single factor or measurement Multiple measurement or factor
are involved
Degree Degree of conformity Degree of reproducibility
factor Single factor Multiple factor
Concerned
with
Systemic error Random Errors
Represent How closely result agree with the
standard value
How closely result agree with
one another
Relationship For the parameter to be
consistently and reliably accurate,
it must also be precise
Result can be precise without
being accurate, alternatively
result can be precise and
accurate

Significant Figures
 FAQ:
 Explain Significant Errors.
 Significant Figures are digits in a number that carry meaning and contribute to
the precision
 All measurement provide useful information about its magnitude and associated
uncertainly.
 Important consideration about significant figure;
 1) any non-zero digits or trapped zeros are significant figures.
 2) leading or trailing zero are not considered as significant figures.
 3)Scientist must maintain the same number of significant figures when going
between decimal and scientific notation.
 4) in multiplication or division process final answer should contain the same
number of significant figures as the original number with the fewest significant
figure.

Pharmaceutical Analysis &Errors

Pharmaceutical Analysis &Errors

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