Introduction to Laboratory Analysis

Study Notes

This lecture introduces principles of laboratory analysis, focusing on solute and solvent concepts.
Clinical lab analyses frequently determine the concentration of substances in solutions.
Common solution samples include blood, serum, urine, and spinal fluid.

A solution is a homogeneous mixture of one or more solutes dispersed in a solvent.
In lab practice, solutes are often measured and referred to as analytes.

Molarity (M): Moles of solute per liter of solution.
- Formula: M = n solute / V solution
  - M = molarity (mol/L)
  - n solute = moles of solute (mol)
  - V solution = volume of solution (L)
Molality (m): Moles of solute per kilogram of solvent.
- Formula: m = n solute / m solvent
  - m = molality (mol/kg)
  - n solute = moles of solute (mol)
  - m solvent = mass of solvent (kg)
Mass percent (w/w%): Mass of solute divided by the total mass of solution, multiplied by 100.
- Formula: Mass Percent = (m solute / m solution) x 100
  - m solute = mass of solute (g)
  - m solution = mass of solution (g)
Volume percent (v/v%): Volume of solute divided by the total volume of solution, multiplied by 100.
- Formula: Volume Percent = (V solute / V solution) x 100
  - V solute = volume of solute (mL or L)
  - V solution = total volume of solution (mL or L)
Mole fraction (X): Ratio of moles of one component to the total number of moles in the mixture.
- Formula: X_A = n_A / (n_A + n_B)
  - X_A = mole fraction of component A
  - n_A = moles of component A
  - n_B = moles of component B
Normality (N): Number of equivalents of solute per liter of solution
- Formula: N = equivalents of solute / V solution
  - N = normality (eq/L)
  - V solution = volume of solution (L)

Reference standard materials are highly purified compounds with well-defined characteristics.
The quality of these materials is essential for obtaining accurate analytical results in pharmaceutical and other analytical methods.

Spectroscopy techniques including UV-VIS, mass spectrometry, atomic absorption, fluorescence, FT-IR, X-ray diffraction, atomic emission, and ICPOES.
Separations methods like electrophoresis and chromatography (GC, HPLC)
Microscopy techniques, such as scanning electron microscopy and transmission electron microscopy.
Thermal analysis methods involving thermogravimetry analysis and bomb calorimetry.
Electrochemical analysis methods, including coulometry, potentiometry, polarography, voltammetry, conductimetry, and amperometry.

Qualitative analysis identifies substances, while quantitative analysis determines the amount.

Quantitative analysis uses numerical data, while qualitative analysis uses non-numerical data like text or images.
Quantitative analysis is objective, minimizing subjectivity, while qualitative analysis embraces subjectivity and explores understanding.
Quantitative research aims for hypothesis testing and prediction, while qualitative research aims for exploratory understanding and context.