Spd 20a uv detector

Mefloquine and verapamil were quantified in feline plasma based on modified HPLC method [16 (link)]. The HPLC system consisted of a Shimadzu LC-20AT delivery unit, DGU-20A3 HT degassing solvent delivery unit, SIL-20A auto injector, SPD-20A UV detector and CTO-20A column oven. Shimadzu LC Solution software version 1.24 (Kyoto, Japan) was used for chromatographic control, data collection and data processing. Chromatographic separation was performed with a Microsorb-MV C18 column (250 mm × 4.6 mm i.d., 5.0 μm; Varian, Mulgrave, VIC, Australia) with a 1.0 mm Optic-guard C18 pre-column (Choice Analytical, Thornleigh, NSW, Australia) under a pressure of 1,900 psi at 25°C. The isocratic mobile phase consisted of a mixture of 25 mM sodium phosphate buffer with 1.0% triethylamine adjusted to pH 2.5 and acetonitrile and methanol (50:25:25, v/v/v) at a flow rate of 1.0 mL/min. The injection volume was 10 μL per sample. The diode array detector was set at a wavelength of 220 nm. The retention times of verapamil and mefloquine were approximately 8.5 and 14.5 minutes, respectively.

Optical rotation indices were determined in methanol on a Rudolph Autopol II digital polarimeter (Rudolph, Hackettstown, NJ, USA). ESI-MS analysis was performed on a Quatro Premier instrument (Waters, Milford, MA, USA). HR-ESI-MS spectra were recorded on an Agilent Technologies 6550 Q-TOF (Santa Clara, CA, USA). 1D- and 2D-NMR spectra were recorded on Bruker-AVANCE 400 (Bruker, Rheinstetten, Germany) and Bruker-AVANCE 600 instrument (Bruker, Rheinstetten, Germany) using TMS as an internal standard. Analytical HPLC was performed on a Waters e2695 Separations Module system coupled with a 2998 Photodiode Array Detector and an Accurasil C-18 column (4.6 mm × 250 mm, 5 μm particles, Ameritech, Chicago, IL, USA). Semipreparative HPLC was performed on a system comprising an LC-6AD pump equipped with an SPD-20A UV detector (Shimadzu, Kyoto, Japan) and an Ultimate XB-C18 (10 mm × 250 mm, 5 μm particles) or YMS-Pack-ODS-A (10mm × 250 mm, 5 μm particles) column. Silica gel was purchased from Qingdao Haiyang Chemical Group Corporation (Qingdao, China).

HPLC-DPPH^•-scavenging online analysis was carried out on a Waters HPLC system (Waters Corporation, Milford, MA, USA) as previously described [21 (link)] with minor changes. The Hypersil C18 analytical column (250 × 0.46 cm, 5 µm; Supelco Analytical, Bellefonte, PA, USA) was used for compound separation. The mobile phase consisted of 0.4% formic acid in water (A) and acetonitrile (B). The elution profile was at the start point 90% A, then changing to 60% in 45 min, after that, in 50 min A was decreased to 5%, then in 53 min increased to 90% A, then it was held at 90% for 3 min, and in 2 min it was returned to initial conditions and the column was equilibrated for 5 min. The decrease of absorbance after the reaction of radical scavengers with DPPH^• was measured at 515 nm with the variable-wavelength Shimadzu SPD–20A UV detector (Shimadzu Corporation, Kyoto, Japan), while the identification of compounds was performed by using the Waters Acquity UPLC system (Milford, MA, USA).

Precoated silica gel GF254 plates (SiO2; Qingdao Haiyang Chemical Industry). Column chromatography (CC): (SiO2, 60–100 and 200–300 mesh, Qingdao Haiyang Chemical Industry), Sephadex LH-20 gel (Pharmacia Biotek), and ODS (40–63μm; YMC, Japan). HPLC: Shimadzu Prominence LC-20A liquid chromatography, with LC-20AT pumps, SPD-20A UV detector (Shimadzu Co., Japan) as well as YMC-Pack ODS-A column (250mm×10mm, 5μm) (YMC Co., Japan). NMR Spectra: BrukerAvance 600 III spectrometer;δ in ppm, with Me4Si as internal standard; J in Hz. ESI-MS:Q Exactive mass spectrometer(Thermo Scientific).

BSA, HRP, and protamine were purchased from Sigma-Aldrich. NIPAAm, DEAEMA, and DMAEMA were obtained from TCI (Shanghai, China). AAC, VPBA, tBAAm, azodiisobutyronitrile (AIBN), 4-dimethylaminopyridine (DMAP), N,N’-diisopropylcarbodiimide (DIC), adenosine, and dopamine were obtained from J and K Chemical (Beijing, China). 3-Aminopropyl silica (silica@NH₂, diameter, 5 μm; pore size, 100 Å) was purchased from Boinna-Agela Technologies (Tianjin, China). Hydrocortisone, prednisolone acetate, dexamethasone, and hydrocortisone butyrate were purchased from the National Institute for Food and Drug Control (Beijing, China). All the chemicals were analytical grade. DEAEMA and DMAEMA were purified by an Al₂O₃ column to remove p-hydroxyanisole (MEHQ) before use.
FTIR spectra were obtained using a PerkinElmer (Boston, MA, USA) FTIR spectrometer. HPLC spectra were obtained using a Shimadzu LC-20AT HPLC system with a Shimadzu SPD-20A UV detector. The temperature was controlled by a CTO-20AC column controller (Shimadzu, Japan). Elemental analysis was conducted using an Elemental Vario MICRO CUBE analyzer (Germany). TGA results were obtained using a Discovery TGA instrument (TA Instruments, USA). Differential scanning calorimetry (DSC) spectra were obtained using a Q2000 DSC instrument (TA Instruments, USA).

The chemical profile of MSJZT was analyzed by HPLC using methods described previously (Lu et al., 2016 (link)). HPLC analysis was performed using a Shimadzu LC-20AT system (Tokyo, Japan) equipped with an SPD-20A UV-detector and a CBM-102 workstation. The mobile phase consisted of solvent A (water with 0.1% phosphoric acid) and solvent B (acetonitrile). An elution program was performed as follows: 0–10 min at 10% of B, 10–20 min at 13% of B, 20–25 min at 17% of B, 25–27 min at 18% of B, 27–33 min at 21% of B, 33–38 min at 21% of B, 38–43 min at 24% of B, 43–63 min at 25% of B, 63–73 min at 45% of B, and 73 min at 80% of B. The flow rate was 1 ml/min, and the total injection volume was 10 μl. Data analysis was performed using the Similarity Evaluation System for Chromatographic Fingerprint of Traditional Chinese Medicine.

Five milligrams of MTAE (Alfa Aesar, Lancashire, UK) was dissolved with 5.0 mL of artificial gastric juice (actual concentration of MTAE: 1 mg/mL or 7.45 mM). The tube was incubated for 0.5–30 h at 37°C, a 200 μL aliquot of the solution was withdrawn at several time points, and residual MTAE and MTA (Matrix Scientific, Columbia, SC, USA) formed in the artificial gastric juice were measured by using reverse-phase HPLC–UV. The levels of MTAE and MTA was measured using an HPLC model LC-20AT with a SPD-20A UV detector (Shimadzu, Kyoto, Japan). A YMC-pack Pro C18-RS (Ø4.6 × 150 mm) analytical column was used for MTAE and MTA analyses based on reverse phase chromatography. A 10 μL aliquot of sample was injected and isocratically eluted using 18% acetonitrile in 0.1% trifluoroacetate mobile phase. The UV absorbance at 230 nm was used to detect MTA at 3.5 min and MTAE at 23.5 min.