Integrated on-line sample clean-up using cation exchange restricted access sorbent for the LC determination of atropine in human plasma coupled to UV detection

in Journal of Pharmaceutical & Biomedical Analysis (2005), 36(5), 947-954

A new, simple and fully automated liquid chromatographic (LC) method with UV detection has been developed for the direct determination of atropine in plasma. Sample clean-up was based on the use of cation ... [more ▼]

A new, simple and fully automated liquid chromatographic (LC) method with UV detection has been developed for the direct determination of atropine in plasma. Sample clean-up was based on the use of cation exchange restricted access material (RAM) in a pre-column, coupled to LC by means of a column switching system. After direct injection of a 200 microl-volume of plasma sample, the biological matrix was washed out for 10 min using a washing liquid composed of 2 mM lithium perchlorate adjusted to pH 3.0 and methanol (97:3; v/v). By rotation of the switching valve, atropine was then eluted in the back-flush mode for 2 min and transferred to the analytical column packed with octadecyl silica by the LC mobile phase constituted of a mixture of acetonitrile and potassium phosphate buffer (pH 3.0; 50 mM) containing 2 mM sodium heptanesulfonate (16:84; v/v). The UV detection was performed at 220 nm. The method was validated according to a new approach based on accuracy profile over a concentration range from 25 ng/ml, corresponding to the limit of quantitation, to 1000 ng/ml. The method was then applied for the determination of atropine in plasma after intravenous administration to hospitalised patients. [less ▲]

Evaluation of a novel anion-exchange restricted-access sorbent for on-line sample clean-up prior to the determination of acidic compounds in plasma by liquid chromatography

in Journal of Chromatography. A (2004), 1030(1-2), 95-102

A new kind of silica-based restricted-access material (RAM) with anionic properties has been tested in pre-columns for on-line solid-phase extraction of acidic compounds from directly injected plasma ... [more ▼]

A new kind of silica-based restricted-access material (RAM) with anionic properties has been tested in pre-columns for on-line solid-phase extraction of acidic compounds from directly injected plasma samples prior to their determination by reversed-phase liquid chromatography (LC), using the column-switching technique. The outer surface of the porous RAM particles contains hydrophilic diol groups while diethylaminoethyl (DEAE) groups are bound to the internal surface which gives the sorbent the properties of a weak anion exchanger towards low-molecular-mass compounds. Due to an appropriate pore diameter (about 6 nm), macromolecules, such as proteins, are physically excluded from the pores and flushed directly out during the sample clean-up process, while small compounds have access to the inner surface and can be retained mainly by electrostatic interactions. The retention capability of this novel packing material has been tested for some hydrophilic acidic compounds such as aspartic acid, glutamic acid, ascorbic acid and acetylcysteine as well as for some more hydrophobic drugs such as naproxen, ibuprofen and diclofenac, used as model compounds. The influence of the composition of the washing liquid on the retention of the analytes in the pre-column has been investigated. The efficiency of the sorbent to clean-up complex matrices was also tested using human plasma and urine samples. A generic washing liquid composition was then selected in order to obtain efficient and selective sample clean-up as well as a high recovery of the acidic analytes. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

Evaluation of novel restricted access sorbents with ion exchange properties for on-line sample clean-up prior to the LC determination of acidic of basic compounds in plasma

Poster (2004)

Use of a novel cation-exchange restricted-access material for automated sample clean-up prior to the determination of basic drugs in plasma by liquid chromatography

in Journal of Chromatography. A (2002), 975(1), 145-155

Evaluation of a new kind of cation exchange restricted access sorbent for on-line solid phase extraction of basic drugs from plasma prior to their determination by liquid chromatography

Poster (2002)