ANALYTICAL CHEMISTRY
GIRLIE LEOPOLDO ┃1 ST SEMESTER ┃2025-2026 ┃MODULE 01
Overview of Analytical Chemistry
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Analytical Chemistry: The
branch
of
chemistry focused on determining the
composition of a sample.
Answers two key questions:
o Qualitative Analysis: Identifies what
substances
(elements
or
compounds) are present in a sample.
o Quantitative Analysis: Measures how
much of a specific substance, known
as the analyte, is present in
numerical terms.
Often, both qualitative and quantitative
analyses are performed together as part of
a single analytical process.
Importance:
Analytical
chemistry
is
essential across various fields, including
science, industry, and medicine, due to its
role
in
understanding
material
composition.
Types of Analysis
1.
2.
Key Terms in Analytical Chemistry
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Applications of Analytical Chemistry
Analytical chemistry has practical applications in
multiple domains, enabling precise measurements
for real-world purposes:
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Medicine: Measures the concentration of
oxygen (O₂) and carbon dioxide (CO₂) in blood
samples to monitor patient health.
Environmental
Science:
Quantifies
hydrocarbons, nitrogen oxides (NOₓ), and
carbon monoxide (CO) in automobile
exhaust to
improve emission-control
systems.
Food Science: Determines the nitrogen (N)
content in foods to calculate their protein
content, which indicates nutritional value.
Metallurgy: Analyzes carbon, nickel, and
chromium in steel during production to
ensure desired properties like strength,
hardness, corrosion resistance, and ductility.
Agriculture:
Helps
farmers
adjust
fertilization and irrigation schedules based
on soil and plant analysis to optimize crop
growth.
Qualitative Analysis:
o Identifies the chemical identity of
elements or compounds in a sample.
o Example: Determining that a sample
contains iron or glucose.
Quantitative Analysis:
o Measures the relative amounts of
each analyte in a sample, expressed
in
numerical
terms
(e.g.,
concentration in mg/L).
o Example:
Calculating
the
percentage of zinc in an alloy.
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Aliquot: A small, measured portion of a
solution or suspension taken from a larger
sample for analysis.
o Example: Taking 10 mL from a 100
mL solution to test for sugar
content.
Analyte: The specific component in a sample
that is being measured or identified.
o Example: In a water sample, the
analyte might be lead (Pb) if testing
for contamination.
Assay: The process of determining the
amount of a specific material in a sample,
as indicated by its name.
o Example: An assay of a zinc alloy
measures the zinc content to
confirm its composition.
Calibration: The process of establishing a
relationship
between
the
analyte
concentration and a measurable quantity,
such as an instrument’s signal.
o Example:
Using
known
concentrations of a chemical to
create a calibration curve for a
spectrometer.
Heterogeneous: Describes a material with
visually or microscopically distinguishable
parts, such as coal, animal tissue, or soil.
o Example: Soil may contain sand,
clay, and organic matter, making it
heterogeneous.
ANALYTICAL CHEMISTRY
GIRLIE LEOPOLDO ┃1 ST SEMESTER ┃2025-2026 ┃MODULE 01
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Matrix (Sample Matrix): All components in a
sample that contain the analyte, excluding
the analyte itself.
o Example: In a blood sample, the
matrix includes plasma, cells, and
other substances, while the analyte
might be glucose.
Quartering: A non-mechanical method to
reduce a large, representative sample into
smaller
portions
for
testing
while
maintaining its composition (see Figure 1
for a visual representation).
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Overview of Quantitative Analytical Methods
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Example: Dividing a large soil sample
into smaller portions for nutrient
testing.
Sample/Laboratory Sample: A portion of
material prepared from a larger (gross)
sample for testing, designed to represent
the bulk material’s composition.
o Example: A small piece of ore taken
from a larger rock sample for metal
content analysis.
Sampling: The process of collecting a small
amount of material that accurately
represents the composition of the larger
bulk material.
o Example: Collecting a small scoop of
soil from a field to test for pesticide
residues.
Selective: Techniques or reactions that
work for a small group of analytes but not
all.
o Example: A test that detects only
certain metal ions, like copper and
iron.
Specific: Techniques or reactions that work
for only one analyte, providing high
precision.
o Example: A chemical reaction that
detects only glucose in a sample.
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Additional Notes
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Analytical chemistry combines qualitative
and quantitative approaches to provide
comprehensive
insights
into
sample
composition.
The accuracy of results depends heavily on
proper sampling and calibration to ensure
reliable data.
Understanding the matrix is crucial, as it
can affect the detection of the analyte (e.g.,
other substances in a sample may interfere
with measurements).
Quantitative
Analytical
Methods:
Techniques used to measure how much of
an analyte (a specific component) is present
in a sample, expressed in numerical terms
(e.g., concentration, mass, or percentage).
These methods are critical in analytical
chemistry
for
providing
precise
measurements in fields like medicine,
environmental science, and industry.
4 General Areas of Quantitative Analytical Methods
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2.
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Gravimetric Methods:
o Determine the mass of the analyte
or a compound chemically related to
it.
o Example: Measuring the mass of a
precipitate formed by reacting the
analyte with a reagent to calculate
its amount.
o Simple Explanation: Weighing a
substance (or something it forms)
to figure out how much is present.
Volumetric Methods:
o Use the volume of a solution
containing a reagent that reacts
completely with the analyte.
o Example: Titration, where a known
volume of a reagent solution is
added to react with the analyte
until a reaction endpoint is reached.
o Simple Explanation: Measuring how
much liquid reagent is needed to
react with the substance being
tested.
Electroanalytical Methods:
o Measure electrical properties such as
potential (voltage), current, or
resistance to determine the sample’s
composition.
o Example: Using a sensor to measure
the electrical current produced by
an analyte in a solution.
ANALYTICAL CHEMISTRY
GIRLIE LEOPOLDO ┃1 ST SEMESTER ┃2025-2026 ┃MODULE 01
Simple
Explanation:
Using
electricity (like voltage or current)
to find out what’s in a sample.
Spectroscopic Methods:
o Based on the interaction of
electromagnetic radiation (e.g., light)
with analyte atoms or molecules, or
the emission of radiation by the
analyte.
o Example: Using a spectrometer to
measure how much light is absorbed
by a sample to determine analyte
concentration.
o Simple Explanation: Shining light on
a sample or detecting light it gives
off to measure what’s inside.
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Simple Explanation: Pick a method based on
precision needs, time/money, and test
scope.
The Chemical Analysis Process
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Overview: A step-by-step process
accurate results (see Figure 2).
Major Steps:
for
Classical vs. Instrumental Methods
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Classical Methods:
o Include gravimetric and volumetric
methods.
o Often
involve
wet
chemical
procedures,
using
reagents
in
solution
and
reactions
with
dissolved analytes.
o Example: Mixing solutions in a lab to
cause a reaction that can be
measured by weight or volume.
Instrumental Methods:
o Include
electroanalytical
and
spectroscopic methods.
o Rely on advanced equipment like
spectrometers or electrodes for
precise measurements.
o Example: Using machines to detect
electrical
signals
or
light
interactions for analysis.
Acquiring the Sample
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Choosing a Quantitative Analytical Method
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Overview: Selecting a method requires
experience and intuition.
Factors to Consider:
o Accuracy Required: High precision for
tests like blood gases (O₂, CO₂).
o Resources: Time (e.g., gravimetric is
slow, spectroscopic is fast) and
money (e.g., instrumental is costly,
classical is cheaper).
o Samples and Components: Multiple
analytes favor spectroscopic; single
analyte suits specific methods.
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Definition:
Sampling
collects
a
representative portion of the bulk material
(matrix).
Importance: Non-representative samples
invalidate results.
Challenges:
o Heterogeneous materials (e.g., soil)
need quartering to reduce size.
o Biological (e.g., blood gases) requires
preserving integrity (e.g., cooling).
Simple Explanation: Sample must match the
bulk, like a small taste reflecting a big dish.
Eliminating Interferences
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Definition: Interferences (e.g., other ions)
enhance or reduce analyte signals.
Importance: Removal is key for accurate
measurement.
Methods: Isolate or mask interferents with
selective or specific techniques.
Simple Explanation: Filter out noise to hear
the main signal.
ANALYTICAL CHEMISTRY
GIRLIE LEOPOLDO ┃1 ST SEMESTER ┃2025-2026 ┃MODULE 01
Calibrating and Measuring Concentration
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Definition: Calibration links measured
property (X) to analyte concentration (cA =
kX).
Process:
Use
aliquots
with
known
concentrations to find k.
Simple Explanation: Calibrate like setting a
scale with known weights.
Calculating and Evaluating Results
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Overview:
Process
data
and
assess
reliability.
Process: Calculate analyte concentration,
estimate errors, interpret results.
Simple Explanation: Do the math and check
if it’s reliable.
Processing the Sample
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Preparing a Laboratory Sample:
o Grind and mix for homogeneity.
o Moisture Content (MC): MC (%) = [(W
- D) / W] × 100.
▪ Example: Wet = 10.5000 g,
Dry = 8.3257 g, MC = 20.708%
(5 sig figs).
▪ Dry weight: 5.1234 g wet →
4.0624 g dry.
o Dry sample or adjust for moisture.
Replicate Samples: Analyze 3+ similar
portions for reliability.
Preparing Solutions:
o Physical: Dissolve with acid or heat.
o Chemical: Convert to measurable
form (e.g., Mn → MnO₄⁻ for
absorbance).
Simple
Explanation:
Prepare
sample
uniformly, account for moisture, and
transform it for testing.
Additional Notes
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Method
Selection:
Balance
accuracy,
resources, and analytes.
Sampling: Must be representative.
Interferences: Manage for complex matrices.
Calibration:
Ensures
accurate
measurements.