The document outlines the critical steps in chemical analysis, emphasizing the importance of proper sample preparation and representation for accurate results. It details various steps such as problem definition, specification setting, method selection, and sample treating processes to ensure meaningful analysis. Additionally, it highlights the necessity of pre-treatment to address issues related to sample state, interference, and analyte concentration.

1. Introduction
Steps in ChemicalAnalysis
PreliminaryTreatment of Sample
Preparation of Samples for Analysis

2. Introduction:
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 The most important single step in analysis is taking a sample
of the material to be analysed.
the most critical aspect of analysis.
 Sample is portion of a material.
collected according to a defined sampling procedure.
 The sample taken for analysis should be:-
representative the whole material
free of interferents.
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Requirements:
I. Sample must be taken that is sufficient for all the analysis to
be carried out comfortably.
II. Sample must be representative of the material being
sampled.
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Gross
sample
Gross
sample
• Its size may vary from
grams to several pounds
• Portion of Gross sample
Analytical
sample
Analytical
sample
• Several replicates may be done by
taking separate analysis samples

4. Steps:
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 There are different steps in drug analysis.
 The pharmaceutical analyst should be involved in every step.
 The following unit operations are common to most types of
drug analysis.
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5. Steps…
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i. Defining the problem-what do we really need to know?
 What information is needed?-Qualitative and/or Quantitative.
 What will the information be used for?
 When it will be needed?
 What is the budget?
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6. Steps…
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ii. Specification setting
 specify or set a std with which his/her/ results can be
compared to give any decision about the analyte.
E.g. Pb ≤ 20 ppm in AmpicillinTrihydrate Raw-material
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7. Steps…
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iii. Selecting a method- vital step in drug analysis
 The method to be used will depend on:-
Type of analysis required (elemental, molecular...etc.)
The number of samples to be analysed.
Complexity of the sample as well as the number of components in the
sample.
The analyst’s skills and training in d/t techniques and instruments.
The facilities, equipment and instruments available.
The sensitivity and precision required.
The cost and budget available.
The time for analysis and how soon results are needed.
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8. Steps…
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iv. Obtaining a representative sample
impossible to analyze the whole thing
 To produce meaningful information, an analysis must be
performed on a sample whose composition faithfully represents
from which it was taken.
raw material,
intermediate product,
finished product,
 container and
 packaging materials.
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9. Steps…
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v. Preparing the sample for analysis.
 Whatever drug’s state is, there might be a need for pre-treat
before the main analysis is performed.
vi. Performing the measurement
 qualitative or
 Quantitative
 Most chemical analyses are performed on replicate samples.
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10. Steps…
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vii. Interpretation of the data obtained
 The analyst should critically evaluate whether the results are
reasonable and relate to the analytical problem originally
stated.
 Example.Assay ofAmpicillinTrihydrate RM
Specification : (96-100.5)%
Result: 90.3%
Interpretation-fail
viii. Conclusion and reporting
 Example.TheAmpicillinTrihydrate Sample does not comply
with a requirement of the given specification, and hence should
be rejected.
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11. Preliminary Treatment of Sample
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Sample Preparation
 In analysis, sample preparation refers to the ways in which a
sample is treated prior to its analysis.
 Sample preparation may involve
dissolution,
reaction with some chemical species,
pulverizing,
treatment with a chelating agent,
masking, filtering,
dilution, sub-sampling….
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 There are three key issues that often arise that necessitate
pre-treatment of a sample prior to analysis:
The sample is in the wrong physical state for the analysis method
(e.g., the method requires a liquid but you have a solid sample),
The sample has interfering matrix components that may give
either a false positive or negative reading in the measurement, and
The sample has too low an analyte concentration to be detected by
the instrument.

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Sample pre-treatment
Steps in sample pretreatment
A.Homogenization
– Is done in order to have a representative sample
– Is done by grinding,shaking,mixing etc.
B.Dissolving
Criteria in solvent selection
 Must allow complete solubility of the analyte.
 Must not interfere in a particular analytical methods.
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C.Performing necessary chemical separations
 Precipitation, extraction into an immiscible solvent,
chromatography and distillation
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Reading Assignment
I. Sampling of different sample
II. Sample storage

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Thank YOU a lot!!!
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