Cp 401 ph meter

The pH of the carrots was measured using a CP-401 pH meter (Elmetron, Zabrze, Poland). The pH meter electrode was placed in 20 mL of analyzed carrot juice. Measurements were conducted in triplicate for each sample.

The carbon material portions of 0.02 g were placed in flasks and flooded with 50 mL of a dye solution of a given concentration (25–250 mg/L), and the contents were shaken at 22 ± 1 °C for 24 h. Spectrophotometric measurements were carried out with a spectrometer Cary 100 Bio (Agilent, Santa Clara, CA, USA). Rhodamine B absorbs the irradiation of λ_max = 553 nm. The amount of rhodamine B adsorbed on the oxidized mesoporous carbons was calculated from Equation (2): $$q_e=\frac{C_0-C_e}{m}\times V$$
where: C₀—initial rhodamine B concentration (mg/L); C_e—equilibrium rhodamine B concentration (mg/L); m—the mass of mesoporous carbon sample (g); V—volume of rhodamine B solution (L). The experimental adsorption studies were carried out twice and are shown with a standard deviation error.
The effects of pH (CP-401 pH-meter, ELMETRON, Zabrze, Poland) of the dye solutions, temperature, and contact time of the sample/rhodamine B on the sorption capacities of mesoporous carbons were studied.

To determine active acidity, a pH measurement of 20% solutions of drone brood and royal jelly in distilled water was performed using a CP-401 pH meter (Elmetron, Zabrze, Poland). To determine the free acidity, 50 mL of 20% appropriate extract was titrated by 0.1 M NaOH to reach a pH of 8.3 measured by pH meter. The results were expressed in mval/g (mL 0.1N NaOH/g) of wet weight (WW).

To determine active acidity, a pH measurement of 20% solutions of honey extract in boiled, cold distilled water was performed using a CP-401 pH meter (Elmetron, Zabrze, Poland). To determine the free acidity, 50 mL of 20% appropriate honey extracts were titrated by 0.1 M NaOH to reach a pH of 8.3 measured by pH meter. The results were expressed in mEq/100 g.

For the determination of acidity, 20% solutions of honey in distilled water were prepared. To determine active acidity, a pH measurement was used using a CP-401 pH meter (Elmetron, Zabrze, Poland). To determine the free acidity, 50 mL of 20% honey solution was titrated by 0.1 M NaOH to reach a pH of 8.3 measured by pH meter. The results were expressed in mval/kg.

The research material was bulk milk obtained from 23 Simmental cows. The cows were kept in a traditional system on a farm located in south-eastern Poland. Feeding in the spring and summer was based mainly on pasture forage with the addition of hay and cereal meal. Milk was collected three times in the spring/summer season. Each time the volume of milk for testing was 6 litres.
The acidity of the milk was determined, i.e., potential acidity (in Soxhlet-Henkl’s degree (°SH) and expressed as lactic acid content, taking into account that 1 °SH = 0.0225% of lactic acid) according to IDF/ISO [22 ] and active acidity (pH) with a CP-401 pH meter (Elmetron, Zabrze, Poland). The proximate chemical composition, i.e., crude protein, fat, lactose and dry matter content, were determined with an Infrared Milk Analyzer (Bentley Instruments, Chaska, MN, USA), and casein content according to AOAC 998.06 [23 ]. To assess the hygienic quality of the milk, the somatic cell count (SCC) was determined by flow cytometry (Somacount 150; Bentley Instruments, Chaska, MN, USA), as well as the total microbial count (TMC) in CFU/mL by the plate method, using deep inoculation according to PN-EN ISO 8261:2002 [24 ] and PN-EN ISO 4833-2:2013 [25 ].

The aqueous solutions were prepared in water deionized with Hydrolab HPL10 UV system. The pH of solutions was set with HClO₄ or simply adjusted with the concentrated acid and controlled with micro pH combination electrode (Sigma Aldrich) filled with 3 M KCl/saturated AgCl solution combined with CP-401 pH-meter (Elmetron, Zabrze, Poland). The concentration of CblCN was determined from the molar absorption coefficient. All reactions were performed in the presence of air under ambient conditions.