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

Abstract

The absolute limit of detection usually expresses the minimum amount of analyte detectable, while the relative limit of detection refers to the minimum concentration of analyte detectable. These concepts and their differences are obviously familiar to all analytical spectroscopists. Nevertheless, the two definitions are used liberally in the literature. For example, it is not uncommon to refer to exceptional sub-femtograms detection limits for a technique used to analyse ultratrace levels of an element in water and to a modest part per million detection limit of another technique used to characterise the microdistribution of an element in a sample mass of about one microgram. In this paper, an attempt is made to point out that the terms "ultratrace analysis" and "microanalysis" must refer to two conceptually different approaches and that there are cases in which one definition is more appropriate than the other. It is argued that, while there is no objection in reporting both detection limits when a single technique is evaluated, one has to be careful in choosing the most appropriate definition when different analytical techniques are compared.

Laser-Induced Breakdown Spectroscopy (LIBS), Part II: Review of Instrumental and Methodological Approaches to Material Analysis and Applications to Different Fields

“…Since LIBS is sampling only minute amounts of sample, relative detection limits are not inherently relevant as the absolute counterpart. 202 In fact, the common knowledge that LIBS is not as sensitive as other analytical methods is somewhat misleading, in the sense that an ∼1 ppm relative detection limit (which admittedly does not sound very spectacular nowadays) often translates into an absolute detection limit in the femtogram range (10 −15 g). The advent of micro-sampling at the sub-micrometer level is expected to even lower such a limit into the attogram range (10 −18 g).…”

Laser-Induced Breakdown Spectroscopy (LIBS): Fast, Effective, and Agile Leading Edge Analytical Technology

“…However, it is important not to fall in the mistake of comparing trace analysis and microanalysis. 43 What can be said beyond any reasonable doubt is that LIBS may routinely achieve absolute detection limits in the femtogram range with a single pulse vaporizing low ng of sample.…”

Study of Matrix Effects in Laser Plasma Spectroscopy by Combined Multifiber Spatial and Temporal Resolutions

“…The effects of the persistent aerosol were also investigated and optimized for best performance . The matrix effects of compound speciation were described in detail, ,, as well as those related to the matrix composition. ,, …”