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Combined reversed phase and anion exchange solid phase extraction for the assay of the neuroprotectant NBQX in human plasma and urine
Author(s) -
Ingwersen Steen H.
Publication year - 1993
Publication title -
biomedical chromatography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 65
eISSN - 1099-0801
pISSN - 0269-3879
DOI - 10.1002/bmc.1130070314
Subject(s) - chemistry , chromatography , solid phase extraction , detection limit , extraction (chemistry) , urine , ion suppression in liquid chromatography–mass spectrometry , high performance liquid chromatography , quantitative analysis (chemistry) , tandem mass spectrometry , mass spectrometry , biochemistry
A combination of reversed phase and anion exchange solid phase extraction (SPE) was investigated for the liquid chromatographic assay of the neuroprotectant agent NBQX in human plasma and urine. Reversed phase SPE alone using a variety of phases failed to yield sufficiently pure extracts for the assay of plasma in the low ng/mL concentration range using UV detection. However, using Bond Elut Certify II TM SPE columns containing a mixture of reversed phase and anion exchange functionalities markedly improved the purity of plasma extracts. Furthermore, a change of detector wavelength from UV (294 nm) to the visible region (380 nm) removed some minor interfering peaks originating from plasma. Using optimized SPE conditions with an extraction recovery of 92.3% and a high performance liquid chromatographic procedure with Lichrospher TM C 18 as the stationary phase, the lower limit of quantitation in human plasma was 2 ng/mL (corresponding to 0.75 ng injected on column). Intra‐assay coefficients of variation ranged from 9.6% at 2 ng/mL to 1.3% at 10 ng/mL. A similar SPE procedure was applied to human urine with acceptable recovery (88.3%), but an analytical column of different selectivity (Chromspher TM BC 18 ) was necessary in order to avoid interference from the urine. The limit of quantitation for the urine assay was 25 ng/mL and the intra‐assay precision ranged from 4.6% at 25 ng/mL to 2.2% at 500 ng/mL.