## 1 Introduction  
The most representative chromatographic procedures for analysing micropollutants in water samples are based on multiresidue analysis with gas chromatography (GC). This instrumental technique requires volatile, thermally stable compounds, and many of the substances of interest in environmental samples tend to be adsorbed and decomposed on the columns or injector. Therefore, derivatisation reactions must be used [1]. Liquid chromatography (LC) and ultra-high-performance liquid chromatography (UHPLC) are now being used in combination with mass spectrometry (MS) for target analytes and for identifying nontarget analytes that are highly polar and non-volatile and have high molecular weights, making them incompatible with GC. Consequently, both the targeted and non-targeted analytes can be analysed or identified within a single analytical run. Therefore, liquid chromatography-mass spectrometry (LC-MS) combined with a sample pre-concentration/clean-up step is employed due to its excellent sensitivity and selectivity [2]. Sample treatment and enrichment processes are crucial during environmental analyses because the concentrations typically found in environmental waters are very low and the matrices are highly complex. Sample preparation may include clean-up and pre-concentration procedures to ensure that the analytes are found at a suitable concentration level. Liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are exhaustive traditional preparation techniques used to extract and pre-concentrate different families of analytes from environmental water samples. The need to reduce solvent volumes and to avoid using toxic organic solvents during LLE and SPE has led to adaptations of existing sample-preparation methods toward the development of new approaches. Consequently, miniaturisation has become a key factor while pursuing these objectives, and new techniques have been developed. Microextraction techniques are generally defined as non-exhaustive sample preparation methods that utilise a very small volume of the extracting phase (in the range of \(\mu\)L) relative to the sample volume. Analytes are extracted using a small volume of a solid or semi-solid polymeric material through solid-phase microextraction (SPME) or of a liquid through solvent microextraction (SME). Despite the substantial structural differences between both techniques, they share similar features because they are both microextraction approaches [3]. Both methods are useful alternatives for sample preparation due to their simplicity, effectiveness, low cost, minimal solvent use and excellent abilities to clean up samples. In this work, we review some of the most commonly used microextraction techniques and their applications toward the determination of some families of micropollutants in environmental liquid samples using mainly LC-MS.  
Until the mid-1990s, the organic trace analysis of water mainly focused on persistent organic pollutants (POP), such as polychlorinated biphenyls (PCBs), polyciclic aromatic hydrocarbons (PAHs), organochlorine pesticides, _etc._, based on their physicochemical characteristics (hydrophobicity, bioaccumulation and biomagnification through the trophic aquatic chain). Most of these substances have been banned, and their environmental concentrations are strictly controlled. However, interest in the fate and role of organic micropollutants, which they are present in the aqueous environment in nanograms or micrograms per litre, has increased. Many of these compounds are employed ashousehold chemicals. Several pharmaceutical drugs, disinfection agents, pesticides and different personal care products can be included in this group [4], and these chemicals are also called emerging contaminants. This term refers to compounds that were not considered or known to be significant in terms of distribution and/or concentration in the past but are now widely detected [5].