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Since amino acids are components of peptides and proteins, the analysis of amino acids is important from the viewpoints of biochemical, medical and clinical aspects. However, since most amino acids possess neither strong ultraviolet/visible absorption nor fluorescence, they are usually detected after fluorogenic derivatization using dansyl chloride 1 , 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole 2 , orthophthalaldehyde (OPA)/N-acetylcysteine 3 , naphthalenedialdehyde(NDA) /NaCN 4 , fluorescein isothiocyanate (FITC) 5 and so on. Of these, dansyl chloride 6-9 , OPA/N-acetylcysteine 10,11 , NDA/NaCN 12 and FITC [13][14][15][16] have been employed for the fluorescent determination of amino acids by capillary electrophoresis (CE). Although FITC derivatization seems to be suitable for the sensitive determination of amino acids by CE, because of matching of the excitation maxima of the derivatives with the emission wavelength of the argon ion laser, CE separation of the bulky FITC derivatives is not easy. [13][14][15][16] The aim of this study was to develop a method for separating and determining FITC-amino acids by capillary electrophoresis with laser-induced fluorescence detection. We reexamined the separation condition of the FITCamino acids and succeeded in the separating 20 FITCamino acids by combining two migration systems using α-cyclodextrin (CD) or 10% methanol as a modifier. Experimental ChemicalsThe amino acids used were L-amino acids, which were purchased from Takarakosan (Tokyo, Japan), Kanto Chemical (Tokyo, Japan) and Nacalai Tesque (Kyoto, Japan). FITC was purchased from Dojindo (Kumamoto, Japan). α-, β-and γ-cyclodextrins (CDs) and O-methyl α-CD were obtained from Tokyo Chemical Industry (Tokyo, Japan). Water was purified by a Milli-Q reagent system (Millipore, Bedford, MA, USA). All other reagents used were of guaranteed grade. Preparation of FITC-amino acidsEach amino acid was dissolved in 22 mM sodium phosphate buffer (pH 9.4) at a concentration of 1 mM. A FITC (2 mM) solution was prepared with acetone. Each amino acid solution (200 µl) was mixed with the FITC solution (200 µl) and incubated at 50˚C for 5 h. CE conditions for separation of FITC-amino acidsThe CE system used was the P/ACE System 5010 (Beckman Instruments Inc., Palo Alto, CA, USA). Excitation was performed by an argon-ion laser at a wavelength of 488 nm; the emission was measured at a wavelength of 520 nm, and the absorbance was mea- A method for the separation and determination of amino acids by capillary electrophoresis with laser-induced fluorescence detection has been developed. At first, the condition for the derivatization of amino acids with fluorescein isothiocyanate (FITC) was studied; it was proved to be optimal at 50˚C for 5 h. Next, the separation of 20 FITC-amino acids was attempted by using an unmodified fused silica capillary. Actually, 18 kinds of FITC-amino acids were separated with 96 mM sodium borate buffer (pH 9.5) containing either 25% acetone (separation system 1) or 10% methanol (separation system 2). The resolutio...

We describe the gravitational lens on a constant-curvature background by using an optical constant-curvature (OCC) approach that allows to explicitly take into account a global geometry of the background space. First, light rays are curves in the space described by an optical metric. The OCC approach focuses on the case that the optical metric for the background spacetime has a constant curvature, for which the exact lens equation on an OCC background [Phys. Rev. D 105, 084022 (2022)] can be used. As a concrete example, next we discuss the gravitatinal lens in Mannheim-Kazanas (MK) solution, which include Rindler and de Sitter terms. By fully taking into account a background dependence of the light deflection, the deflection angle of light consistent with the OCC approach is well defined at large distance. In the OCC approach, finally, we examine the global behavior of the deflection angle and the gravitational lens observables in the Weyl gravity.

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