CHAPTER 1

• ANALYTICAL CHEMISTRY is concerned with the CHEMICAL CHARACTERIZATION of matter
• ANALYTICAL CHEMISTS determine WHAT AND HOW MUCH
• Qualitative analysis


  Involves analysis of data e.g. pictures or objects. This tell us WHAT chemicals are present
• Quantitative analysis


  Involves analysis of numerical data. It tell us how much of the analyte in the sample
• Steps in the Analytical Process

  • Defining the problem
  • Obtaining a representative sample
  • Preparing the sample to analyze the problem
  • Performing necessary chemical separation
  • Performing the measurement
  • Calculating the results and presenting the data problem
• Defining the Problem


  • Literature review to gather information
  • Sample type and quantity
  • Analyte to be determined, its chemical & physical
  • MSDS of chemical required (e.g. H2O2)
  • Select the method
  • How sensitive is the method
  • Separation required to eliminate the interferences
  • Experience, equipment available, cost and time required and etc.
• Obtaining a Representative Sample

  • Proper sampling procedures to ensure result integrity
  • Sample must be homogenous from parent batch
  • Heterogeneous sample results depend on how well the sample is taken and treated after sampling
  • Transport & storage: Sample composition may change with time after collection because of internal chemical changes (oxidation, microbe, degradation), reaction with the air, or interaction with its container ~ Proper preservation is required
• Tools for sampling


  • Boerner Divider
  • Sampling probe
  • Wheaton 885250 clear PVC sampling tool
• Preservation techniques


  • Choice of appropriate sampling container (glass for organic & polyethylene for inorganic in 1-2% acidic condition) and store in the dark
  • Addition of chemical stabilizer such as antioxidant or antibacterial agents
  • Freezing the sample to avoid thermal degradation, antibacterial agents & sample volatilization
  • Adsorption on a solid phase
• Sampling operations


  • Lot
  • Bulk sample/ gross sample
  • Laboratory sample
  • Test portion
• Types of samples


  • Grab sample
  • Composite sample
  • In situ sampling
• Preparing the Sample for Analysis (solid & semisolid)

  • Sample Size Reduction
  • Precaution in Grinding Operations
  • Drying of samples
• Preparing the Sample for Analysis (Inorganic)

  • Adding reagent to dissolve and decompose samples
• Preparing the Sample for Analysis (Filtration)

  • Qualitative-grade paper
  • Ashless quantitative-grade paper
  • Hardened-grade paper
  • Borosilicate glass fiber & quartz filter
  • Membrane filter
  • Hollow-fiber membrane cartridge
  • Fritted ware
  • Filter aids
• Derivatization


  A chemical reaction between an analyte and a reagent that changes its chemical and physical properties
• Uses of Derivatization


  • To change the molecular structure or polarity of the analyte for better chromatography
  • To stabilize an analyte
  • To improve detectability
  • To change the matrix for better separation
  • Rapid & Quantitative with minimal by-product
  • Excess reagent should be easily removed and should not interfere with analysis
• Performing Necessary Chemical Separations

  • Example: Solid phase extraction, liquid-liquid extraction, distillation, ion-exchange separation
  • To pre-concentrate
  • To reduce / remove interferences ~ extraction, clean-up, adding acids, ashing, separation, masking
• Gravimetric analysis


  Involves the selective separation of the analyte by precipitation, followed by the very nonselective measurement of weight of the precipitate
• Volumetric/ Titrimetric analysis


  The analyte reacts with a measured volume of reagent of known concentration. A change in some physical or chemical property signals the completion of the reaction
• Instrumental Analysis Techniques

  • Electroanalytical
  • Spectroscopy
  • Chromatography
• Spectroscopy Techniques


  • Fourier Transform Infra Red (FTIR) Spectroscopy
• Chromatography Techniques


  • High Performance Liquid Chromatography (HPLC)
• Performing the Measurement


  • Perform replicate blanks analysis to determine trace impurities
  • Optimization of measurement condition
  • Establish calibration curve
  • Introduce internal standard
  • Standard addition
  • Analyze blind sample, spiked sample ~ verification
  • Establish quality control chart
  • Validate the accuracy of result by comparative analysis of standard reference material or other standard method
• General distribution of time spend on analysis: sample preparation 61%, data management 27%, collection 6%, analysis 6%
• Survey results for the distribution of error generated during analysis (1991): sample preparation 29.4%, operator 18.6%, contamination 3.9%, sample introduction 5.9%, integration 7.8%, chromatography 6.9%, instrument 7.8%, calibration 8.8%, column 10.8%
• Sample handling


  • Sample registration
  • Sample should be completely identified and labeled
• Analyte


  Substance measured
• Determination


  Process of measuring the analyte
• Constituents in sample


  • Major (>1%)
  • Minor (0.1-1%)
  • Trace (<0.1%)
  • Ultra-trace (ppm, ppb or PPT)