3.2. Surfactant concentration
Triton X-114 is one of the nonionic surfactant extensively used for CPE [24]. It has been successfully applied for extracting a wide range of analytes from biological [15] and [19] and environmental samples, including estrogens, vitamin A, vitamin E [16], kinds of proteins, as well as metal ions [20] and [21]. Additional advantages include commercial availability with high purity, low toxicity and low cost, high density of the resulting surfactant reach phase facilitating the phase separation by centrifugation, and relatively low coacervating temperature [22].
Reports indicate that the amount of Triton X-114 not only affected the extraction efficiency but also the resulting surfactant-rich phase volume after phases separation [15]. The smaller the initial surfactant concentration, the smaller is the resulting surfactant-rich phase volume leading to higher sensitivity of the methodology. However, it is well known that a small surfactant-rich phase volume (