Analytical Chemistry Overview

Analytical Chemistry: A Study of Matter

• Analytical chemistry deals with the identification and quantification of substances, both qualitatively (what is present) and quantitatively (how much is present).
• Qualitative analysis: determines the identity of the constituent species in a sample.
• Quantitative analysis: Determines the amount of a constituent species present in a sample and is achieved by measuring weight or volume.
• Fundamental analysis: improves methods for achieving better results.
• Chemical analysis: provides chemical or physical information about a sample's constituents.
• Sample: A limited quantity intended to represent a larger amount.
• Analyte: The component of interest in the sample.
• Matrix: The remainder of the sample, excluding the analyte.

Classification of Constituent

• Major constituent: component present in a concentration of 1-100%.
• Minor constituent: component present in a concentration of 0.01-1%.
• Trace constituent: component present in a concentration less than 0.01%.

Techniques and Methods

• Technique: a chemical or physical principle used to analyze a sample.
• Method: the application of a technique for determining a specific analyte in a specific matrix.

Typical Quantitative Analytical Procedures

• Select a Method: consider accuracy, reliability, time, cost, and sample complexity.
• Sampling: Obtain a representative sample, especially important for mass products.
• Sample Preparation and Handling:
  • Dissolution or digestion of samples, avoiding decomposition conditions.
  • Preparation of solid samples: Solids are ground to a suitable particle size to obtain a homogeneous sample.
• Replicate Samples: Multiple portions of the material carried through the analysis simultaneously, ensuring accuracy and reliability.
• Interferences: Species that affect the measurement other than the analyte, causing errors by enhancing or reducing the quantity being measured.
• Eliminating Interferences: Use blank control to eliminate interferences.
• Calibration and Measurement: The process of determining the exact relationship between the measured property and the property sought.
• Calculation and Data Reduction: Determining the final result using the obtained data.
• Evaluating Results and Estimating Reliability: Uses statistics to ensure the analytical result is reliable.

What is Chemistry?

• Chemistry is the study of the composition, structure, properties, and reactions of matter.
• Chemistry explores how substances are made, how they change under different conditions, and how they can be combined or separated.

Fields of Chemistry

• Physical chemistry: Studies the physical properties of matter and how they relate to chemical processes.
• Analytical chemistry: Focuses on identifying and quantifying the components of a sample.
• Organic chemistry: Deals with the study of carbon-containing compounds.
• Inorganic chemistry: Deals with the study of compounds that do not contain carbon.
• Biological chemistry: Explores the chemistry of living organisms.

Analytical Chemistry

• Analytical chemistry aims to separate, identify, and quantify the components of a sample (analyte).
• Qualitative analysis determines the chemical identity of the components present in a sample.
• Quantitative analysis determines the amount of each component present in a sample.
• Instrumental analysis relies on instruments to analyze samples.

Areas of Analytical Chemistry

• Clinical analysis: Analyzes biological samples like blood, urine, and tissue for diagnosis.
• Pharmaceutical analysis: Determines the properties, toxicity, and quality of pharmaceutical products.
• Environmental analysis: Identifies and quantifies pollutants in soil, water, and air.
• Forensic analysis: Analyzes evidence related to crime, such as DNA and blood.
• Industrial quality control: Ensures the quality and consistency of products in manufacturing processes.
• Bioanalytical chemistry: Detects and analyzes biological components such as proteins, DNA, and RNA.

Quantitative Analysis Methods

• Gravimetric method: Measures the mass of a sample.
• Volumetric method: Measures the volume of a solution or uses volume to determine the amount of a sample.
• Instrumental method: Uses instruments to analyze the sample, often relying on techniques like:
  • Electroanalytical methods: Based on electron transfer.
  • Spectroscopy: Includes techniques like mass spectrometry, which analyzes the mass-to-charge ratio of ions.
  • Separation methods: Techniques like gas chromatography (GC) and high-performance liquid chromatography (HPLC) separate components of a mixture.

Miscellaneous Analytical Methods

• Mass spectrometry: Analyzes the mass-to-charge ratio of an analyte's breakdown products.
• Radiochemical methods: Measure rates of radioactive decay of an analyte.
• Kinetics: Measures reaction rates.
• Thermal conductivity: Measures the rate of heat transfer through a substance.
• Optical activity: Measures how an analyte interacts with polarized light.
• Refractometry: Measures the bending of light passing through a substance (refractive index).

Analytical Methods Overview

• Gravimetry: Based on weight.
• Titrimetry: Based on volume.
• Electrochemical: Measures electrical properties like potential, current, and charge.
• Spectral: Uses electromagnetic radiation to analyze samples.
• Chromatography: Separates components of a mixture.
• Chemometrics: Uses statistical methods to analyze data.

Detecting Analytes

• Physical means: Analytes can be detected based on their:
  • Mass
  • Color
  • Refractive index
  • Thermal conductivity
• Electromagnetic radiation (Spectroscopy): Analytes can be detected based on their interaction with light through:
  • Absorption
  • Emission
  • Scattering
• Electric charge (Electrochemistry): Analytes can be detected based on their electrical properties.
• Mass spectrometry: Analyzes the mass-to-charge ratio of ions.

Steps in Quantitative Analysis

• Select a method: Consider factors like accuracy, reliability, cost, time, and sample complexity.
• Sampling: Obtain a representative sample that accurately reflects the composition of the entire bulk material.
• Sample preparation: Includes steps like dissolution or digestion of the sample. It's crucial to avoid potentially decomposing conditions, which can be especially challenging for biological samples.

This quiz explores the fundamentals of analytical chemistry, focusing on the identification and quantification of substances. It covers qualitative and quantitative analysis, as well as concepts such as samples, analytes, and the classification of constituents. Test your knowledge of these essential topics in the study of matter.