# Recent Applications of Deep Eutectic Solvents in Environmental Analysis
## Recent Applications of DESs in Environmental Analysis
### Analysis of Inorganic Compounds in Environmental Samples  
Although most applications of DESs in environmental samples analysis have mainly been focused on the evaluation of organic contaminants, the study of inorganic species has also been carried out (see Table 2[27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41]). In this regard, heavy metals such as copper [29, 35], lead [27, 29, 35, 40], tungsten [28], arsenic [28, 31, 37, 38], cadmium [27, 35, 40], cobalt [27], nickel [27, 33, 35], palladium [34, 35], antimony [31, 37], mercury [30], and chromium [37, 41] represent the main applications of DESs to the analysis of inorganic species, but also trace elements like molybdenum [37], selenium [37, 39], and vanadium [37], and compounds including ammonia [36], metal oxides [32], chlorides [32], acetates [32], phosphates [32], sulphates [32], and carbonates [32] have been studied. Regarding the matrices evaluated, the analysis of environmental waters stands out and different types of waters have been analysed [27, 29, 30, 31, 33, 34, 35, 36, 38, 39, 40, 41], including lake, tap, river, well, sea, dam waters and wastewater. However, other samples such as sediments [29, 38] and soils [29, 37, 38, 40], mining residues [28], incinerated sewage sludge ash [32], or dust [34] and catalytic converter [34] have also been evaluated. \begin{table} \begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Sample** \\ **(Amount)** \\ \end{tabular} } & \multirow{2}{*}{**Analytics**} & **DES** & **Extraction** & **Analytical** & **Recovery** & **LODs** & **Comments** & **Reference** \\  & & & **Amount** & & & & & & - DES has a dual role: & extractant and complex & agent. \\  & & & & & & & - & - 4.4\({}^{\prime}\)-thiobisbenzenethiol & & \\  & & & & & & & - & - & - \\ River, lake, & \
\begin{tabular}{c} Pb(II), \\ Cd(II), \\ Co(II), \\ Ni(II) \\ \end{tabular} &
\begin{tabular}{c} THTDPC-chioslasicylic \\ Acid \\ (1:2; 30 \(\mu\)L) \\ \end{tabular} & UA-SAP- & HPLC-UV & 91–102 & 0.05-0.13 ug/L & 1.3 were also studied. & [27] \\  & & & & & - & - Final extract was 3-fold & diluted with ACN. \\  & & & & & - & - Accuracy was evaluated \\  & & & & & & - The method was applied & to the analysis of real \\  & & & & & & - & Samples. \\  & & & & & & - & ChClactic acid (1:2) and & \\  & & & & & & - & - \\ Mining & & & & & & - & - \\ residues (39 g) & & & & & & - & - \\  & & & & & & - & - \\  & & & & & & - & - \\  & & & & & & - & - \\  & & & & & & - & - \\  & & & & & & & - \\  & & & & & & & - \\  & & & & & & & - \\  &  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Sample** \\ **(Amount)** \\ \end{tabular} } & \multirow{2}{*}{**Analytes**} & \multicolumn{2}{c}{**DES**} & \multirow{2}{*}{**Extraction**} & \multirow{2}{*}{**Analytical**} & \multirow{2}{*}{**Recovery**} & \multirow{2}{*}{**LODs**} & \multirow{2}{*}{**Comments**} & \multirow{2}{*}{**Reference**} \\  & & **Amount** & & & & & & - & - \\ \hline \hline \multirow{9}{*}{\begin{tabular}{c} Incinerated \\ sewage sludge \\ ash \\ (0.1 g) \\ \end{tabular} } & \multirow{9}{*}{\begin{tabular}{c} AlPO\({}_{4}\) \\ and \\ Ca\({}_{0}\)(PO\({}_{4}\))\({}_{2}\) \\ \end{tabular} } & \multirow{9}{*}{\begin{tabular}{c} ChCl and \\ DMU-based DESs \\ (-5 g) \\ \end{tabular} } & \multirow{9}{*}{\begin{tabular}{c} **Exraction** \\ **Technique** \\ \end{tabular} } & \multirow{9}{*}{\
\begin{tabular}{c} **Analytical** \\ **Technique** \\ \end{tabular} } & \multirow{9}{*}{
\begin{tabular}{c} **Recovery** \\ **\%** \\ \end{tabular} } & \multirow{9}{*}{**LODs**} & \multirow{9}{*}{**Comments**} & \multirow{9}{*}{**Reference**} \\  & & & & & & & - \\ \hline \hline \end{tabular} \\ \hline \hline \end{tabular} 
\end{table}
Table 2: _Cont._  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{ \begin{tabular}{c} **Sample** \\ **(Amount)** \\ \end{tabular}  } & \multirow{2}{*}{**Analytes**} & \multirow{2}{*}{ \begin{tabular}{c} **DES** \\ **(Molar Ratio;** \\ **Amount)** \\ \end{tabular}