Fluoxetine and norfluoxetine analysis by direct injection of human plasma in a column switching liquid chromatographic system

Abstract

A column switching LC method is presented for the analysis of fluoxetine (FLU) and norfluoxetine (NFLU) by direct injection of human plasma using a lab-made restricted access media (RAM) column. A RAM-BSA-octadecyl silica (C-18) column (40 mm x 4.6 mm, 10 microm) is evaluated in both backflush and foreflush elution modes and coupled with a C-18 lab-made (50 mm x 4.6 mm, 3 microm) analytical column in order to perform online sample preparation. Direct injection of 100 microL of plasma samples is possible with the developed approach. In addition, reduction of sample handling is obtained when compared with traditional liquid-liquid extraction (LLE) and SPE. The total analysis time is around 20 min. A LOQ of 15 ng/mL is achieved in a concentration range of 15-500 ng/mL, allowing the therapeutic drug monitoring of clinical samples. The precision values achieved are lower than 15% for all the evaluated points with adequate recovery and accuracy. Furthermore, no matrix interferences are found in the analysis and the proposed method shows to be an adequate alternative for analysis of FLU in plasma.

Biocompatible in-tube solid phase microextraction coupled with liquid chromatography-fluorescence detection for determination of interferon α in plasma samples

“…The obtained results are in agreement with the exclusion profile found by Santos Neto et al [22,23,32] and by Cass and co-workers [21,25] using conventional RAM-BSA columns.…”

“…These plasma samples were spiked with interferon alpha 2a and used for optimization of the RAM in-tube SPME process and analytical validation of the developed method. [20], and by other authors [21][22][23]. Initially, 50 mL phosphate buffer solution (0.05 mol L −1 , pH 6.0) was percolated through the capillary at a flow rate of 1.0 mL min −1 ; followed by 25 mL BSA solution 1.0 mg mL −1 (prepared in phosphate buffer solution), and by 25 mL glutaraldehyde solution (25%, v/v).…”

Selective Nanoparticles in Microextraction

“…(9) A very successful strategy is based on the formation of a bovine serum albumin (BSA) layer around a typical SPE sorbent such as silica. (10) Selected examples of the applicability of both materials to improve the selectivity of (micro)extraction procedures will be briefly described in the following sections.…”

Surface hydrophilic modification with a sugar moiety for a uniform-sized polymer molecularly imprinted for phenobarbital in serum

“…To get both selective and restricted access functional materials, many different methodologies that combine molecular imprinting with the restricted access function have been developed [13,14]. A widely used approach is the hydrophilic modification of the surface of materials, such as introducing hydrophilic monomers pre-polymerization, grafting hydrophilic polymeric chains or coating a hydrophilic polymer network layer on a MIP [15][16][17][18][19].…”