TY - JOUR
T1 - Coupling of acetonitrile deproteinization and salting-out extraction with acetonitrile stacking for biological sample clean-up and enrichment of hydrophobic compounds (porphyrins) in capillary electrophoresis
AU - Li, Qi
AU - Huie, Carmen W.
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2006/11
Y1 - 2006/11
N2 - A new sample pretreatment approach in CE was developed for concurrent biological sample clean-up and the concentration of hydrophobic compounds based on the combination of ACN deproteinization with salting-out extraction. Further enhancement in concentration detection sensitivity was achieved by coupling (offline) salting-out extraction with an online CE sample enrichment technique known as "ACN stacking". By optimizing the pH of salting-out extraction, a number of model compounds (hydrophobic porphyrins with clinical significances), i.e. zinc-protoporphyrin, protoporphyrin, and coproporphyrin (CP) III and I, can be efficiently extracted from the aqueous sample into a smaller volume organic solvent (ACN) phase and an enrichment factor of ca. 100 can be obtained. The pressure injection of the enriched ACN phase (containing ca. 1% NaCl) into the CE capillary at 10% capillary volume resulted in additional concentration of the various hydrophobic porphyrins, allowing for a combined enrichment factor of ca. 1000 to be obtained. Calibration curves obtained for the determination of a pair of positional isomers with significant diagnostic value, urinary CPIII and CPI, were found to be linear between 10-300 ng/mL (with R2=0.999), and LODs (absorbance detection at 400 nm) were ca. 0.8 ng/mL (1.1 nmol/L of CPIII or CPI). Based on a single salting-out extraction, intraday precisions (nine consecutive injections) for both CPIII and CPI (at spiked concentrations of 10-300 ng/mL into urine) in terms of migration time and peak area were found to be within the range of 0.2-0.5 and 0.8-2.9%, respectively.
AB - A new sample pretreatment approach in CE was developed for concurrent biological sample clean-up and the concentration of hydrophobic compounds based on the combination of ACN deproteinization with salting-out extraction. Further enhancement in concentration detection sensitivity was achieved by coupling (offline) salting-out extraction with an online CE sample enrichment technique known as "ACN stacking". By optimizing the pH of salting-out extraction, a number of model compounds (hydrophobic porphyrins with clinical significances), i.e. zinc-protoporphyrin, protoporphyrin, and coproporphyrin (CP) III and I, can be efficiently extracted from the aqueous sample into a smaller volume organic solvent (ACN) phase and an enrichment factor of ca. 100 can be obtained. The pressure injection of the enriched ACN phase (containing ca. 1% NaCl) into the CE capillary at 10% capillary volume resulted in additional concentration of the various hydrophobic porphyrins, allowing for a combined enrichment factor of ca. 1000 to be obtained. Calibration curves obtained for the determination of a pair of positional isomers with significant diagnostic value, urinary CPIII and CPI, were found to be linear between 10-300 ng/mL (with R2=0.999), and LODs (absorbance detection at 400 nm) were ca. 0.8 ng/mL (1.1 nmol/L of CPIII or CPI). Based on a single salting-out extraction, intraday precisions (nine consecutive injections) for both CPIII and CPI (at spiked concentrations of 10-300 ng/mL into urine) in terms of migration time and peak area were found to be within the range of 0.2-0.5 and 0.8-2.9%, respectively.
KW - Acetonitrile deproteinization
KW - Acetonitrile stacking
KW - Capillary electrophoresis
KW - Hydrophobic compounds
KW - Salting-out extraction
UR - http://www.scopus.com/inward/record.url?scp=33751299964&partnerID=8YFLogxK
U2 - 10.1002/elps.200600306
DO - 10.1002/elps.200600306
M3 - Journal article
C2 - 17022021
AN - SCOPUS:33751299964
SN - 0173-0835
VL - 27
SP - 4219
EP - 4229
JO - Electrophoresis
JF - Electrophoresis
IS - 21
ER -