“…There are several methods for extracting and preconcentrating heavy metals from natural matrices, such as ion exchange [16], co-precipitation [17], coagulation [18], chemical precipitation, cloud point extraction [19], and liquid-liquid extraction (LLE) [19], reverse osmosis [20], membrane filtration [21], coagulation [18], co-precipitation [17], electrochemical precipitation [22] and SPE have been developed. Among the mentioned methods, SPE is the most widely used method for the pre-concentration of heavy metal ions from environmental samples due to its ease, speed, low cost, and minimal reagent consumption [23].…”