Mp220 ph meter

Collagen type I (stock concentration of 5.82
mg/mL in 0.1 M acetic acid) was isolated from muscle tendon of mice
by Arthro-Anda Tianjin Biologic Technology Co., Ltd. (Tianjin, China).
Bovine serum albumin (BSA) (closely related to human serum albumin
in structure, size, and composition) and γ-globulin were obtained
from Aladdin (Shanghai, China). 1,2-Dipalmitoyl-sn-glycero-3 phosphatidylcholine (DPPC, 16:0) was purchased from Sigma-Aldrich
(Tianjin, China) with >99% purity. The PBS buffer was prepared
by
the formula (137 mM NaCl, 10 mM phosphate salt, and 2.7 mM KCl) at
pH 7.4 confirmed using a pH meter and stored at 4 °C before use.
The water used in all the experiments was purified using a three-stage
Millipore Milli-Q Plus 185 purification system (Millipore Corp., Bedford,
MA). The pH values of all the solutions used were determined using
an MP220 pH meter (Mettler-Toledo, Switzerland). All the solutions
were filtered using syringe filters with 0.22 μm-diameter pores.

The collection of xylem sap and the measurement of leaf/stem WP (Boyer, 1967 (link)) and xylem sap pH were conducted between 2 and 7 h from photoperiod start. Xylem sap was collected either from leaf (N. tabacum) or stems (P. sativum, H. vulgare, and V. faba) using a pressure chamber (PWSC 3005, Soilmoisture Equipment Corp., Santa Barbara, CA, United States). Sap was sampled from the second or third fully developed leaf of N. tabacum. After cutting, the cut surface of the petiole/stem was rinsed with distilled water to remove contaminants from the cut cells and the petiole/stem was sealed in the pressure chamber. The first drop of xylem sap was discarded and the pressure was noted as the WP. Pressure was gradually increased up to approx. Around 0.2 MPa above the balancing pressure and 10–40 μl of xylem sap was collected from each leaf (or shoot) over approximately 10 min. The pH of xylem sap was taken by a pH microelectrode (Microelectrodes Inc., Bedford, MA, United States) connected to an MP220 pH meter (Mettler Toledo, Switzerland). Samples were stored at −20°C immediately after pH measurement, until further analysis.

The effect of the pH on the coagulation activity of cynara was studied. The pH of the milk was adjusted to the following values: 5.3; 5.8; 6.3 and 6.8. The measurement of pH of the milk was made using pH meter using an MP 220 pH meter (Mettler‐Toledo GmbH). The measurement was carried out by introducing the two sensors (pH and temperature) in a milk sample preheated to a temperature of 20–25°C. The clotting activity was measured for each pH value.

Dynamics of the fermentation process were controlled based on CO₂ emission in time. To this end, the fermentation samples were weighed on a WTB 2000 scale by RADWAG company (Radom, Poland) every 24 h throughout the alcoholic fermentation. Extract content was determined with a Densito 30 PX densitometer by Mettler-Toledo company (Greifensee, Switzerland). The samples were earlier centrifuged using an MPW-351R laboratory centrifuge (2675 centrifugal force (RCF), 6000× g, 10 min) by MPW MED. INSTRUMENTS company (Warszawa, Poland). Extract content was measured in the resultant supernatant at a temperature of 20 °C. The pH value was measured with an MP 220 pH-meter by Mettler Toledo company (Greifensee, Switzerland).

Chemical oxygen demand (COD) (g/L) was determined by the potassium dichromate method using tube tests and an AL200 COD VARIO Set-Up (Aqualytic, Dortmund, Germany). The pH value was measured using a MP 220 pH meter (Mettler-Toledo, Greifensee, Switzerland).

Physicochemical characteristics of HA samples synthesized using a porogen were examined using a digital pH meter (MP220 pH Meter, Mettler Toledo, Greifensee, Switzerland) and electrical conductometer (MC 226 Conductivity Meter, Mettler Toledo, Greifensee, Switzerland) [30 (link)].