Model 805 manometric module

1,1′-Carbonyldiimidazole (CDI), dextranase (Penicillium sp.), and 3,5-dinitrosalicylic acid (DNS) were purchased from Sigma Chemical Co. (St Louis, MO, USA). Succinic anhydride and 5-benzyl N-(Boc)-glutamate were purchased from Tokyo Chemical Industry (Tokyo, Japan). Dextran (molecular weight: 15–20 kDa) was purchased from Fluka (Sigma Chemical Co.). Celecoxib was ether-extracted from Celebrex capsules (Pfizer, Inc., New York, NY, USA). All other chemicals were reagent grade, commercially available products. Buffer solutions (pH 1.2 and 6.8) were prepared as described in USP XXIII. Thin layer chromatographys (TLCs) were performed on Merck Kieselgel 60 F254. The high-performance liquid chromatography (HPLC) system consisted of a Model 306 pump, a Model 117 UV detector, a Model 234 autoinjector, and a Model 805 manometric module from Gilson (Middleton, WI, USA). A symmetry column C18 (Waters, Milford, MA, USA) (250×4.6 mm) with a guard column (Waters, 3.9×20 mm) was used. Six-week-old male Sprague Dawley rats (Samtako Bio Korea, Kyeong-gi-do, South Korea) were housed in the university animal facility with controlled temperature, humidity, and dark/light cycle. The animal protocol used in this study has been reviewed and approved by the Pusan National University-Institutional Animal Care and Use Committee (PNU-IACUC) on their ethical procedures and scientific care.

The HPLC system consisted of Model 305 and 306 pumps, a 117 variable UV detector, a Model 234 autoinjector, a Model 805 manometric module, and a Model 811C dynamic mixer from Gilson, Inc. (Middleton, WI, USA). The mobile phase consisted of 10% acetonitrile in 0.067 M, pH 4.5 phosphate buffer, passed through a 0.45-µm membrane filter before use. A symmetry C₁₈ column (250×4.6; Waters [Milford, MA, USA]) was eluted with the mobile phase at a flow rate of 1 mL/min. The column eluent was monitored at 319 nm with a sensitivity of 0.01 absorbance units full scale. For the analysis of MTDZ by UV spectrophotometry, a standard calibration curve was constructed from the absorbance at 319 nm of standard MTDZ solutions (1–20 ppm) in a pH 6.8 isotonic phosphate buffer.