Sample Preparation for Trace Analysis by Chromatographic Methods

Abstract

The determination of trace analytes in complex natural matrices often requires extensive sample extraction and preparation prior to chromatographic analysis. Correct sample preparation can reduce analysis time, sources of error, enhance sensitivity and enable unequivocal identification, confirmation and quantification. This overview considers general aspects on sample preparation techniques for trace analysis in various matrices. The discussed extraction/enrichment techniques cover classical methods, such as Soxhlet and liquid-liquid extractions along with more recently developed techniques like pressurized liquid extraction, liquid phase microextraction (LPME), accelerated microwave extraction, and ultrasoundassisted extraction. This overview also deals with more selective methodologies, such as solid phase extraction (SPE), solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE). The adopted approach considers the equilibriums involved in each technique. The applicability of each technique in environmental, food, biological and pharmaceutical analyses is discussed, particularly for the determination of trace organic compounds by chromatographic methods.

Ionic liquid‐based headspace in‐tube liquid‐phase microextraction coupled with CE for sensitive detection of phenols

“…In headspace (HS) extraction, analytes evaporated into the HS above a sample solution and are collected by an extractant . HS extraction is the fastest and cleanest method for analyzing volatile organic compounds and semi‐volatile organic compounds in water or household products, especially when the sample is in a dirty matrix . So, HS extraction is widely used for GC either in laborious off‐line modes or with commercial automatic couplers .…”

Comparative study of wastewater disinfection by-product formation during wastewater disinfection by peracetic acid versus sodium hypochlorite

“…The advantages of LLE are simplicity, high extraction efficiency and sensitivity by using an adequate solvent. The major drawbacks are the higher demand for solvent volume and time, labor intensity, as well as the emulation formation [53][54][55].…”

“…Solid-phase extraction (SPE) removes the target analytes from a water sample by distribution and retention on a solid phase (adsorbents), followed by the evaporation with a stream of nitrogen or air [54,56]. There are three kinds of adsorbents packed into a cartridge or column: carbon-based, silica-based, and polymer-based sorbents [53].…”

“…Compared to LLE, SPE requires less solvent, more quickly, and provides more highly concentrated extracts. However, SPE also has disadvantages such as low extraction efficiency for very polar analytes, high requirement for uniformity of packing, and dependence on water matrix [54].…”

“…It is a more rapid and sensitive technique for both polar and non-polar analytes in water samples, although low storage stability of the samples may be involved. [53][54][55][56]…”