Absolute and/or relative detection limits in laser-based analysis: the end justifies the means

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Trace Analysis

Background:

• The absolute limit of detection (LOD) quantifies the minimum detectable analyte amount.
• The relative limit of detection (LOD) quantifies the minimum detectable analyte concentration.
• Current literature frequently uses these terms interchangeably, leading to ambiguity.

Purpose of the Study:

• To differentiate between ultratrace analysis and microanalysis as distinct conceptual approaches.
• To clarify the appropriate use of absolute versus relative limits of detection in analytical science.
• To guide the selection of the most suitable LOD definition when comparing diverse analytical techniques.

Main Methods:

• Conceptual analysis of detection limit definitions in analytical spectroscopy.
• Review of literature examples illustrating the misuse of absolute and relative LODs.
• Argumentation for distinct applications of ultratrace analysis and microanalysis.

Main Results:

• Absolute LOD is suitable for quantifying minimal analyte amounts (e.g., sub-femtograms).
• Relative LOD is suitable for characterizing analyte concentration in samples (e.g., parts per million).
• The choice of LOD definition impacts the interpretation of analytical technique performance.

Conclusions:

• Ultrateace analysis and microanalysis represent fundamentally different analytical strategies.
• Reporting both absolute and relative LODs is acceptable when evaluating a single technique.
• Careful selection of the appropriate LOD definition is crucial for accurate comparison of different analytical techniques.