Laser induced fluorescence detection

A stereoselective determination of enantiomers of 5, its A -oxide and N-desmethyl metabolites in human urine was developed by capillary electrophoresis using laser-induced fluorescence detection and sulfonated /1-cyclodextrin in the running buffer (01JC(B)169). 

A variety of formats and options for different types of applications are possible in CE, such as micellar electrokinetic chromatography (MEKC), isotachophoresis (ITP), and capillary gel electrophoresis (CGE). The main applications for CE concern biochemical applications, but CE can also be useful in pesticide methods. The main problem with CE for residue analysis of small molecules has been the low sensitivity of detection in the narrow capillary used in the separation. With the development of extended detection pathlengths and special optics, absorbance detection can give reasonably low detection limits in clean samples. However, complex samples can be very difficult to analyze using capillary electrophoresis/ultraviolet detection (CE/UV). CE with laser-induced fluorescence detection can provide an extraordinarily low LOQ, but the analytes must be fluorescent with excitation peaks at common laser wavelengths for this approach to work. Derivatization of the analytes with appropriate fluorescent labels may be possible, as is done in biochemical applications, but pesticide analysis has not been such an important application to utilize such an approach. 

Van Den Beld, C. M. B. and Lingeman, H., Laser-based detection in liquid chromatography with emphasis on laser-induced fluorescence detection, Pract. Spectrosc., 12, 237, 1991. 

Wu, S. and Dovichi, N. J., Capillary zone electrophoresis separation and laser-induced fluorescence detection of zeptomole quantities of fluorescein thiohy-dantoin derivatives of amino acids, Talanta, 39, 173, 1992. 

Baars, M.J. and Patonay, G., Ultrasensitive detection of closely related angiotensin I peptides using capillary electrophoresis with near-infrared laser-induced fluorescence detection, Anal. Chem. 71, 667, 1999. 

Muller, O., Minarik, M., and Foret, F., Ultrafast DNA analysis by capillary Electrophoresis/laser-induced fluorescence detection, Electrophoresis, 19,1436, 1998. 

Lada, M.W., Kennedy, R.T. (1996). Quantitative, in vivo monitoring of primary amines in rat caudate nucleus using microdialysis coupled by a flow-gated interface to capillary electrophoresis with laser-induced fluorescence detection. Anal. Chem. 68, 2790-2797. 

Lee, I.H., Pinto, D., Arriaga, E.A., Zhang. Z., Dovichi, NJ. (1998). Picomolar analysis of proteins using electrophoretically mediated microanalysis and capillary electrophoresis with laser-induced fluorescence detection. Anal. Chem. 70, 4546 4548. 

Mao, Y., Zhang, X.M. (2003). Comprehensive two-dimensional separation system hy coupling capillary reverse-phase liquid chromatography to capillary isoelectric focusing for peptide and protein mapping with laser-induced fluorescence detection. Electrophoresis 24, 3289-3295. 

Solinova V, Kasicka V, Koval D et al (2004) Analysis of synthetic derivatives of peptide hormones by capillary zone electrophoresis and micellar electrokinetic chromatography with ultraviolet-absorption and laser-induced fluorescence detection. J Chromatogr B 808 75-82... 

Tseng H-M, Li Y, Barrett DA (2007) Profiling of amine metabolites in human biofluids by micellar electrokinetic chromatography with laser-induced fluorescence detection. Anal Bioanal Chem 388 433-439... 

Yan W, Sloat AL, Yagi S, Nakazumi H, Colyer CL (2006) Protein labeling with red squarylium dyes for analysis by capillary electrophoresis with laser-induced fluorescence detection. Electrophoresis 27 1347-1354... 

Valproic acid has been determined in human serum using capillary electrophoresis and indirect laser induced fluorescence detection [26], The extract is injected at 75 mbar for 0.05 min onto a capillary column (74.4 cm x 50 pm i.d., effective length 56.2 cm). The optimized buffer 2.5 mM borate/phosphate of pH 8.4 with 6 pL fluorescein to generate the background signal. Separation was carried out at 30 kV and indirect fluorescence detection was achieved at 488/529 nm. A linear calibration was found in the range 4.5 144 pg/mL (0 = 0.9947) and detection and quantitation limits were 0.9 and 3.0 pg/mL. Polonski et al. [27] described a capillary isotache-phoresis method for sodium valproate in blood. The sample was injected into a column of an EKI 02 instrument for separation. The instrument incorporated a conductimetric detector. The mobile phase was 0.01 M histidine containing 0.1% methylhydroxycellulose at pH 5.5. The detection limit was 2 pg/mL. 

The chiral amines (55) were first derivatized by conventional reaction with fluorescene-isothio-cyanate (57) leading to fluorescein-active compounds (58) (Equation (9)) that enable a sensitive detection system, specifically laser-induced fluorescence detection (LIF), to be used.90 Although... 

Fig. 1.14. Multiphoton excitation scheme in Hj showing the laser-induced fluorescence detection method...

Miller reported several monomeric, photolabile CCK agonists and antagonists. The photoreactive residue (L-Bpa) was placed at the N-terminal and a fluorescent reporter group was also linked to it. The CCK receptor in the study was expressed on Chinese hamster ovary-CCKR cells. To identify the labeled domains on the receptor capillary electrophoresis was used with laser induced fluorescence detection. Separate regions were labeled with the two photoprobes, one labeled the first extracellular loop (96-121), while the other probe labeled a fragment in the second extracellular loop (174-195). 

EVANGELISTA, R.A., LIU, M.-S., CHEN, F.-T.A., Characterization of 9-aminopyrene-l,4,6-trisulfonate-derivatize sugars by capillary electrophoresis with laser-induced fluorescence detection, Anal. Chem., 1995,67,2239-2245. 

Another method which uses capillary electrophoresis with laser-induced fluorescence detection can also be employed to detect zearalenone (Maragos and Appell 2007). In order to analyse trace amounts of zearalenone in plants, a sensitive, quick and accurate method, the enzyme-linked immunosorbent assay (ELISA) was developed by Chen et al. 1989. 

K. Arlt, S. Brandt, and J. Kehr, Amino acid analysis in five pooled single plant cell samples using capillary electrophoresis coupled to laser induced fluorescence detection. J. Chromatogr. A 926, 319 325 (2001). 

A.D. Presley, K.M. Fuller and E. A. Arriaga, MitoTracker Green labeling of mitochondrial proteins and their subsequent analysis by capillary electrophoresis with laser-induced fluorescence detection. J. Chromatogr.B, 793 (2003) 141-150. 

Fig. 8. Laser-induced fluorescence detected times-of-flight for NO desorbed from Pt(foil) using 532 nm laser heating. The three traces were obtained while probing (top) NO (F, J—19.5 ,m° 662cm- ), (middle) NO (F J=12.5 , = 281cm- ) and (bottom) NO (F, J = 3.5, i , = 25cm" ). (Adapted from Rrf. 46.)...

Que AH, Palm A, Baker AG, Novotny MV. 2000. Steroid profiles determined by capillary electrochromatography, laser-induced fluorescence detection and electrospray-mass spectrometry. J Chromatogr A 887(1-2) 379-391. 

Bergquist J, Vona MJ, Stiller CO, O Connor WT, Falkenberg T, et al. 1996. Capillary electrophoresis with laser-induced fluorescence detection a sensitive method for monitoring extracellular concentrations of amino acids in the periaqueductal grey matter. J Neurosci Methods 65( 1) 33-42. 

Chen Z, Wu J, Baker GB, Parent M, Dovichi NJ. 2001. Application of capillary electrophoresis with laser-induced fluorescence detection to the determination of biogenic amines and amino acids in brain microdialysate and homogenate samples. J Chromatogr A 914(1—2) 293-298. 

Dawson LA, Stow JM, Palmer AM. 1997. Improved method for the measurement of glutamate and aspartate using capillary electrophoresis with laser induced fluorescence detection and its application to brain microdialysis. J Chromatogr B Biomed Sci Appl 694(2) 455-460. 

Kostel KL, Lunte SM. 1997. Evaluation of capillary electrophoresis with post-column derivatization and laser-induced fluorescence detection for the determination of substance P and its metabolites. J Chromatogr B Biomed SciAppl 695(1) 27-38. 

Lada MW, Vickroy TW, Kennedy RT. 1997. High temporal resolution monitoring of glutamate and aspartate in vivo using microdialysis on-line with capillary electrophoresis with laser-induced fluorescence detection. Anal Chem 69... 

Perez-Ruiz, T., Martinez-Lozano, C., and Galera, R. (2006). Development and validation of a capillary electrophoresis method with laser-induced fluorescence detection for the determination of captopril in human urine and pharmaceutical preparations. Electrophoresis 27(12), 2310—2316. 

---