Microchip analysis of lithium in blood using moving boundary electrophoresis and zone electrophoresis.
The determination of inorganic cations in blood plasma is demonstrated using a combination of moving boundary electrophoresis (MBE) and zone electrophoresis. The sample loading performed under MBE conditions is studied with the focus on the quantitative analysis of lithium. A concentration adjustment takes place when the sample components migrate into the chip during the sample loading step. Using a heart-cutting method, a diluted sample plug is subsequently separated with capillary zone electrophoresis. The excessive dispersion that is typical of the samples with a high ionic strength is thereby prevented. The method can be easily applied to commercially available capillary electrophoresis microchips under the condition that the electroosmotic flow is suppressed. For the first time the lithium concentration is determined in the blood plasma from a patient on lithium therapy without sample pretreatment. Using a microchip with conductivity detection, a detection limit of 0.1 mmol/L is obtained for lithium in a 140 mmol/L sodium matrix.
Vrouwe
Elwin X
EX
BIOS/The Lab-on-a-Chip Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands.
Luttge
Regina
R
Olthuis
Wouter
W
van den Berg
Albert
A
D004553:Electric Conductivity; D004586:Electrophoresis / Q000379:methods*; D046209:Electrophoresis, Microchip; D006801:Humans; D008094:Lithium / Q000032:analysis* / Q000097:blood; D012964:Sodium / Q000737:chemistry
D008094:Lithium; D012964:Sodium