# What is pre-concentration (context: Breath analysis)?

What is the meaning of pre-concentration both in general and specific to this context of

a) "In addition to consistent sampling protocols,.. pre-concentration, and analysis of breath samples require standard methodology, calibration standards..."

b) "Offline breath analysis involves some form of pre-concentration of analytes followed by a separation step using high-resolution GC-MS based detection"

## 2 Answers

Pre-concentration just refers to the process of concentrating a sample before analysis, so that trace components won't be overlooked. If you're looking for something that's only present at a few parts-per-million, you could easily miss it if you used the raw sample, so ideally you want a way to separate off either large, common sources of noise/error, or to just extract the exact components you're looking for.

A quick look suggests, for example, that a key first component to remove in breath analysis is moisture, as some volatile components will dissolve readily in the water and make it harder to detect them.

Anyway, this paper on a few pre-concentration and detection techniques might be informative: Mochalski P, Wzorek B, Sliwka I, Amann A; Chromatogr B Analyt Technol Biomed Life Sci. 2009 Jul 1;877(20-21):1856-66.

Preconcentration is the process by which the concentration of an intended species is increased to gain sensitivity for the subsequent determination.