Drug screening in human plasma by cloud-point extraction and HPLC

Abstract

Cloud-point extraction (CPE) with RP-HPLC/DAD detection was used to develop a screen for six model basic drugs (paracetamol, promazine, amitriptyline, nortriptyline, clomipramine and chlorpromazine) in human plasma. These drugs’ varied hydrophobicities entail different affinities for the micelle-rich phase and CPE extraction efficiencies. Extraction recovery (except paracetamol) was above 80% and reproducibility (RSD%) ranged from 2.88 to 10.26 intraday and from 3.12 to 12.33 interday. The limits of detection were: 0.125 µg mL−1 (promazine and chlorpromazine), 0.25 µg mL−1 (amitriptyline and nortriptyline) and 0.5 µg mL−1 (paracetamol and clomipramine). The method was linear over the ranges: 0.125–1.0 µg mL−1 (promazine and chlorpromazine), 0.25–1.0 µg mL−1 (amitriptyline and nortriptyline), 0.5–1.0 µg mL−1 (clomipramine) and 0.5–10 µg mL−1 (paracetamol). The procedure is a good alternative to the SPE or LLE sample preparation usually used.

Determination of Antidepressants in Human Plasma by Modified Cloud-Point Extraction Coupled with Mass Spectrometry

“…In this paper, the influences of surfactant concentration (Triton X-114), volatile salt (AA—0, 10, 20, and 30% ( w/v )), and extraction pH (about 3.5, 6.8, 10.2) was tested to select the optimal conditions for the simultaneous determination of 21 antidepressants. Other parameters, i.e., volume of reagents and equilibrium time, were used as described previously [ 2 , 31 ]. However, in the current study higher temperature was selected (60 °C).…”

“…On the other hand, too high concentration of surfactant is associated with a high volume of the micelle-rich phase, and the unwanted dilution of the analyte [ 5 , 10 , 32 ]. The range of tested Triton X-114 concentrations, added to samples in multi-compound determination, varied from 1.5 to 9% ( w/v ) [ 1 , 2 , 4 , 5 , 8 , 32 ], with the most frequently used concentration being 4% [ 32 ]. In this study, two variants of Triton concentration (1.5 and 6%) were studied.…”

“…In CPE, the surfactant (such as Triton X-114) in a concentration above the critical micelle concentration (CMC) can exist as a homogeneous isotropic liquid, which separates into two isotropic phases with different concentrations of surfactant. Sample ingredients are separated into the surfactant micelle-rich phase (hydrophobic components when nonionic surfactant is used) and the micelle-poor phase (hydrophilic components) [ 2 ].…”

Determination of trace amounts of Brown HT as a food dye by a CPE-scanometry method

“…The cloud point extraction method has been successfully employed for the pre-concentration of compounds, such as food samples [18][19][20], environmental samples [8,21], biological samples [21,22], dyes [13,[23][24][25], biomaterials [26] and pharmaceuticals [27,28].…”

Triton X-114 cloud point extraction to subfractionate blood plasma proteins for two-dimensional gel electrophoresis

“…The solution is then 67 easily separated (centrifugation) into a hydrophilic surfactant-poor 68 phase and into a surfactant-rich phase with a small volume contain-69 ing the hydrophobic compounds initially present in the solution as 70 they are favorably partitioned in the nonpolar environment [4,5]. 71 Since CPE was introduced by Watanabe and Tanaka [6] in 1978 72 it has been extensively used for the extraction and preconcentra-73 tion of a diversity of metal ions [4], organic pollutants [7], drugs 74 [8], and hydrophobic proteins, especially membrane proteins [9], 75 from environmental and biological samples. The surfactant Triton 76 X-114 (TX-114) is widely used for CPE and since Bordier [10] intro-77 duced it for enrichment of membrane proteins this application has 78 been useful in many studies.…”