We show in this study the comparison between CE/LEDIF and capillary LC/LEDIF analysis of 20 primary amino acids and catecholamines labeled with NDA. It permits to do the best compromise for the neuroscientist needs.
We used NDA (naphthalene-2,3-dicarboxyaldehyde) because it perfectly allows derivatizing primary amines containing molecules at concentrations as low as 100 picomolar, making this method THE labeling method of choice for easy and sensitive detection.
CE-LEDIF Analysis
Instruments | Capillary electrophoresis: Agilent Technologies 7100 CE System Detector: Picometrics ZETALIF LED with LED 450nm/30nm |
Sample | Standards : 10-7M (labeled at 10-6M and diluted 10 times prior to injection) |
Labeling | NDA is a fluorogenic dye which fluoresces weakly in its native form but has a good fluorescent yield when reacted with CN- and a primary amine. Such derivatives are excitable at 450 nm using a LED. |
Method | Capillary: 65 cm x 50 µm ID Run time: 16 minutes Injection: 10 seconds at 50mbar |
CE-LEDIF | |
Run Time | 16 min |
Injection volume | 32 nl |
LOD Glutamate | 8.8.10-10 mol/l |
LOD Gaba | 8.4.10-10 mol/l |
Instruments | Capillary HPLC: Ultimate LC Packing system Detector: Picometrics ZETALIF LED with LED 450nm/30nm |
Sample | Standards : Amino acids at 10-8 M |
Labeling | Amino acids are labeled with NDA |
Method | Mobile Phase: A:Sodium citrate; B: Acetonitrile Buffer 5mM pH=3.2 Flow rate: 5 µL/min, Injection volume: 1 µL, Column: Inertsil ODS3, 3µm 150mm x 300µm GROM Run time: 22 minutes |
Conclusion:
This application allows the simultaneous detection of amino acids and catecholamines with capil.LC-LEDIF and CE-LEDIF. These methods provide the neuroscientist with one of the most powerful tool for sensitivity in analysis of microdialysates.
In CE-LEDIF, the volume of injection of sample is 1 µL, neuroschemist can increase the number of tests on the same sample to provide other analytical data with complementary methods.
Capil.LC-LEDIF | |
Run Time | 22 min |
Injection volume | 1 µL |
LOD Glutamate | 5.5.10-10 mol/l |
LOD Gaba | 2.4.10-10 mol/l |
References
[I] Siri N, Lacroix M, Garrigues JC, Poinsot V, Couderc F. Electrophoresis. 2006, 27, 4446-55
[II] Poinsot V, Rodat A, Gavard P, Feurer B, Couderc F. Electrophoresis, 2008, 29, 207-223
[III] Lacroix M, Garrigues JC, Couderc F. J Am Soc Mass Spectrom. 2007, 18, 1706-13.