Gentamicin sulphate (BP grade) was obtained as a gift from Drugfield Pharmaceuticals Limited (Ogun State, Nigeria), Carbopol Ultrez 21[R] was obtained as a gift from Metchem Limited (Mumbai India/Lubrizol Corporation, USA), Carbopol 940[R] (Lubrizol Corporation, USA), propylene glycol, triethanolamine (TEA) (Merck Germany), Transcutol[R] was obtained as a gift from Gattefosse (Cedex, France), O-Phthalaldehyde
OPA from Fluka (Steiheim Germany).
The method of O-phthalaldehyde
colorimetric which was described by Xu et al.
[USPRwire, Fri Sep 28 2018] Ortho-Phthalic Aldehyde or o-Phthalaldehyde
(received clearance by FDA in October 1999) is a chemical compound commonly abbreviated as OPA.
Liquid chromatographic methods for D-serine analysis are divided into 2 types: chiral derivatization with o-phthalaldehyde
(CPA) in the presence of chiral thiols such as cysteine analogs, followed by HPLC separation on a nonchiral stationary phase, and nonchiral derivatization with fluorescent reagents followed by HPLC separation with chiral columns (3,14).
We purchased William's medium E, insulin, collagenase, Hepes, L-glutamine, penicillin, and streptomycin, NAC, BSO, GSH, o-phthalaldehyde
(OPT), and mouse fluorescein isothiocyanate (FITC) conjugate monoclonal anti-[Beta]-tubulin from Sigma (St.
Several methods have been described to determine carnosinase activity (3, 5, 7, 8,16), based on the reaction of o-phthalaldehyde
(OPA) with histidine, which is liberated from the substrate (17,18).
However, the preparation of o-phthalaldehyde
(OPA) derivatives of gabapentin has been the most popular and practical approach for liquid chromatographic determinations (7-12).
(OPA; Fluka) was of analytical reagent grade, the mercaptoethanol was chemistry-purity grade (No.
HPLC with o-phthalaldehyde
precolumn derivatization to measure total, oxidized, and protein-bound glutathione in blood, plasma, and tissue.
In a second step, heptaminol was measured in urine following precolumn derivatization with o-phthalaldehyde
and reversed-phase HPLC with fluorescence detection (5).