Rqflex10 reflectometer

Saliva samples were thawed and shaken for 10 s at 20 °C (ClassicVortex Mixer, Velp Scientifica, Usmate Velate, Monza y Brianza, Italy) and 15 µL of the saliva sample was poured onto a pH test strip (range 4.0–9.0; Code. 1.16996.0001; Reflectoquant^™ Merck, Darmstadt, Germany) which was introduced in a RQflex^®10 reflectometer (Merck Millipore, Darmstadt, Germany) to provide the pH value. A volume of 30 µL of the saliva sample was poured onto a lactic acid test strip (range 1.0–60.0 mg/L; Code. 1.16127.0001; Reflectoquant^™ Merck, Darmstadt, Germany) which was introduced in a RQflex^® 10 reflectometer (Merck Millipore, Darmstadt, Germany) to provide the lactic acid value.

To gain chemical evidence of how stable in FC3 and FC7 solutions Fe²⁺ is, the concentrations of Fe²⁺ and total Fe were measured following the colorimetric method. Briefly, Fe-containing solutions were diluted with water to a target concentration of 0.5–20 mg/L, and the Fe²⁺ in the solution was reacted with triazine derivative to form a red–violet-colored complex. The solutions were analyzed using an RQflex10 reflectometer (Merck KGaA, Darmstadt, Germany) to quantitate the Fe²⁺ concentrations in each. The solutions were then subjected to the Reflectoquant Iron Test (Merck KGaA, Darmstadt, Germany). Ascorbate acid was added to the solution as a reductant, and the solution was allowed to set for 1 min; the solutions were then analyzed using the RQflex10 reflectometer to determine the total Fe concentrations.