# Understanding the Beer-Lambert Law

• The Beer-Lambert law is an equation that relates the absorption of light to the properties of the material the light is going through.
• It is based on the premise that absorption of light is directly proportional to the concentration of the absorbing species in the solution and the path length the light passes through.
• The law can be expressed as A = εcl where A is absorbance, ε is molar absorbivity, c is concentration, and l is path length.

# Applications of the Beer-Lambert Law

## Spectrometry

• It is one of the key principles applied in spectrometry, especially UV-visible spectroscopy.
• The law allows for the calculation of concentration of a solute in a solution given the absorbance of the solution and the molar absorbivity of the solute.
• As such, spectrometry can be used to test the concentration of different substances including drug levels in pharmaceutical industry.

## Environmental Analysis

• In environmental science, it’s used to measure concentrations of pollutants in water and air samples.
• For instance, it can be used to detect and measure pollutant gases in the atmosphere.

## Biological Applications

• The Beer-Lambert law also finds relevance in biological sciences.
• In medical laboratory investigations, it allows for the determination of concentration of substances such as blood glucose levels or protein concentration in patients’ samples.

## Analytical Chemistry

• The Beer-Lambert law is vital in analytical chemistry for determining the concentration of a solution based on its absorbance.
• This means chemists can estimate the concentration of a particular species in solution by determining the amount of light absorbed by the solution.
• It is also an essential concept in colorimetry, an analytical technique used to determine the concentration of colored compounds in solution.

# Limitations of the Beer-Lambert law

• While the Beer-Lambert law is effective in various fields, it may not be accurate for very high or very low concentrations.
• The law assumes that each particle will absorb individually, an assumption that may not hold true in high concentrations where particles may interact.
• Furthermore, it does not account for physical changes like temperature, pH or ionic strength which might affect absorbance.
• It’s also worth noting that it only applies to solutions where molecules do not undergo association or dissociation.