Determinação de metais alcalinos e alcalino-terrosos em água engarrafada comercializada nas cidades da Matola e Maputo

Abstract

The search for a healthy life has driven the increase in bottled water consumption. Therefore, there has been an unbridled growth in the supply of bottled water in urban regions of Mozambique. However, little is known about the quality of this water due to lack of quality control laboratories in most production facilities as well as the limitation of the conditions for analyzing their quality parameters. In this way, the present study aims to determine alkaline and alkaline earth metals in bottled water sold in the cities of Matola and Maputo. A total of 12 samples were collected in triplicate between October and November 2022, 7 samples in the city of Maputo and the rest in the city of Matola. The concentrations of alkaline metals (Li + , Na + and K + ) and alkaline earth metals (Be 2+ , Ca 2+ , Mg 2+ , Ba 2+ and Sr 2+ ) were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES) and were compared with current national and international legislation. The results showed that brand E has a higher concentration of Li + (aq) (0.381 ± 2+ 0.219 mg/L), Ca 2+ (aq) (35.467 ± 0.517 mg/L), Mg (aq) (24.550 ± 0.517 mg/L); in turn, brand A, 2+ presents higher concentrations of Na + (aq) (66,097 ± 2,627 mg/L), Sr (aq) (0.079 ± 0.001 mg/L) and, G the highest concentration of Ba 2+ (aq) (0.372 ± 0.035 mg/L). Some ions were not detected in certain 2+ 2+ 2+ brands, such as: K + (aq) in J and K; Mg (aq) in J and L, Ca (aq) in J, K and L; the Ba (aq) in B, C, 2+ D, F, J, K and L; and Sr (aq) in B, C, D, F, H, I, J, K and L. Be 2+ (aq) was not detected in all brands. In most brands there is a significant difference between the concentration of the metals analyzed and the value prescribed on the label (p <0.05, 2T). Sodium concentration is below the minimum limit admissible, except in sample A and, the potassium concentration is below the same in all samples. Excluding brand A with 60 mg/L CaCO 3 (moderately hard water) and E with 190 mg/L CaCO 3 (very hard water), the rest are soft water. All metals are below the limit maximum permissible intake as well as the daily intake recommended by legislation. Therefore, there is no health risk in drinking the bottled water evaluated, despite A, E, J, K and L are not recommended for the high-risk group