This work describes the development of an automatic titrometric method in flow-batch with potentiometric detection using alternative and easily accessible materials. Arduino board and its modules, solenoid valves to control the flow rate, peristaltic pump to propel and suction fluids and tubes of inert material to connect the different parts of the Flow-Batch Analyser (FBA) were used. The use of solenoid valves controlled by microcontrollers proved to be efficient for controlling the flow in FBA systems, the correlations of their flow rates as a function of time showed good linearity with correlation coefficients (r) 0.9994 and 0.9997 for the valve 1 and valve 2, respectively, allowing correct addition of pre-established volumes. Accuracy was verified by comparing the results of the proposed method with the classic potentiometric titration with statistically evaluated by Student’s t-test in NaOH with HCl and vinegar with NaOH titrations. Results confirmed the efficiency to use Arduino board and its modules and automatic titrometric method in flow-batch developed in this work allow the implementation of practical disciplines, such as potentiometric titration and flow analysis system in undergraduate courses, making these instruments more accessible, especially for the chemistry students.

This work describes the bioaccessibility in vitro simulated gastric digestion for levels of Zn, Ca, and P in milk and soybean extract samples. Total and dialyzed levels were determined by ICP OES. According to results of the dialyzed samples, it can be concluded that in 250 mL of milk (a glass) the body can be absorb about 1.2 ± 0.2 mg, 14.8 ± 1.2 mg, 4.5 ± 0.8 mg, 2.2 ± 0.4 mg and 4.9 ± 0.6 mg of Zn; 2079 ± 133 mg, 305 ± 4 mg, 2396 ± 16 mg, 2444 ± 54 mg, and 1527 ± 71 mg of Ca; and 2023 ± 275 mg, 811 ± 14 mg, 2688 ± 39 mg, 5089 ± 474 mg and 3467 ± 63 mg of P for raw sheep’s milk, soybean, raw cow’s milk, UHT goat’s milk, and UHT cow’s milk, respectively. These results correspond to approximately 45, 118, and 267% of diary human needed of Zn, Ca, and P, respectively. Accuracy was verified using CRM (NIST 8435) for total levels, and dialyzed samples were compared with FAAS, statistically evaluated by Student’s t-test. Results confirmed the methodology efficiency and allowed an estimate of the bioacessibility of nutrients.

This work describes the development of a peristaltic pump and a photometric detector, using “Arduino” and alternative and low-cost materials for flow analysis system. The analytical calibration curve of the acid-red-283 using the proposed system presents 0.9984 and 3.9% as the coefficients of determination and variation, and 1.1 and 3.8 mg L-1 as limits of detection and quantification, respectively. Three prepared samples of the acid-red-283 (25, 30 and 35 mg L-1) showed recovery between 99 to 104%. For construction of the peristaltic pump and the photometer using Light Emitting Diodes (LED), light-dependent resistor (LDR) were spent less than 10% of the cost was spent on a commercial system employing a peristaltic pump and a spectrophotometer. Furthermore, the peristaltic pump and the photometer developed in this work allow the implementation of practical disciplines, such as molecular absorption spectrophotometry and flow analysis system in undergraduate courses, making these instruments more accessible, especially for the chemistry students.