Pack fa

The content ratio of Mg-St and the tablet hardness were measured in typical poor dissolution samples, A044, A048, A049, A131, B038, B057, B086, and B113 (Table 1). All of these samples were deemed unacceptable in the dissolution test according to Japanese Pharmacopoeia. In these measurements, a sample comprising three tablets were tested per measurement and analyzed using PCA.
The Mg-St determination was carried out by HPLC according to the application data provided by YMC Co., Ltd. (Kyoto, Japan). Using a fatty acid analysis kit, the carboxyl group of Mg-St was converted to 2-nitrophenylhydrazine, enabling highly sensitive detection in the ultraviolet (UV) and visible regions. HPLC analysis was conducted using a YMC-Pack FA (4.6 mm × 250 mm, YMC Co., Ltd., Kyoto, Japan) linked to an HPLC system (Alliance 2695, Waters Corporation, MA, USA) with a UV detector (2487, Waters Corporation, MA, USA). The column oven was kept at 35 °C. The mobile phase was a mixture of dilute hydrochloric acid solution (pH 4–5) and acetonitrile (15:85, v/v). The injection volume was 30 μL. The flow rate was 1.2 mL/min, and the detection wavelength for labeled Mg-St was 230 nm. Margaric acid was added as an internal standard. The analyses were performed in triplicate.
The hardness of the tablets was measured using a digital hardness tester (KHT-40, Fujiwara Scientific Co., Ltd., Tokyo, Japan).

The SHIME software (Prodigest, ver. 4.2.2) allowed online monitoring of the acid (0.5 M HCl) and base (0.5 M NaOH) consumption that was required to control the pH within the desired interval (6.6–6.9). Subsequently, 10 μL of each supernatant of sampled culture broth was immediately used for ammonia analysis using a Fuji Dri-chem Slide NH3-PII (Fujifilm Wako Pure Chemical Corporation) with Fuji Dri-chem (Fujifilm Wako Pure Chemical Corporation). Next, 200 μL of each supernatant was used for SCFA analysis with YMC-Pack FA (YMC Co., Ltd., Kyoto, Japan). The combined isocratic HPLC UV detector (400 nm) was operated with acetonitrile/methanol/water = 30/16/54 as the mobile phase at a flow rate of 1.2 mL/min at a temperature of 50 °C. After encoding the standard curve, each peak was integrated with the LCsolution software (Shimadzu Corporation, Kyoto, Japan, ver. 3.50).