Together of 16 different real samples were tested including food products and pharmaceutical supplements. The samples of fruits were prepared by cutting 100 g of the dried dates and sonicating in 150 ml of DI water. The supplements samples were prepared according to the instructions on the packaging, by dissolving 1 tablet of the mixed electrolytes supplement and potassium supplement purchased from apothecary in 200 ml and 100 ml respectively. The concentrated beetroot soup sample was prepared by 10-fold dilution in DI water. All of the other samples were measured directly without any pretreatment. Detailed information concerning different sample types, as well as pH of samples measured with a standard pH meter (Mettler Toledo, FiveEasy F20, Switzerland) is provided in the Table SI 1.