Exfoliation of Molecular Solids by the Synergy of Ultrasound and Use of Surfactants: A Novel Method Applied to Boric Acid.

Boric acid, H3BO3, is a molecular solid made up of layers held together by weak van der Waals forces. It can be considered a pseudo "2D" material, like graphite, compared to graphene. The key distinction is that within each individual layer, the molecular units are connected not only by strong covalent bonds but also by hydrogen bonds. Therefore, classic liquid exfoliation is not suitable for this material, and a specific method needs to be developed. Preliminary results of exfoliation of boric acid particles by combination of ultrasound and the use of surfactants are presented. Ultrasound provides the system with the energy needed for the process, and the surfactant can act to keep the crystalline flakes apart. A system consisting of a saturated solution and large excess solid residue of boric acid was treated in this way for a few hours at 40 °C in the presence of various sodium stearate, proving to be very promising, and an incipient exfoliation was achieved.

Multi-elemental analysis of commercial wheat flours by ICP-MS triple quadrupole in function of the milling degree.

This preliminary study is focused on an elemental analysis of 60 samples of different commercial grains' flour, including various typologies of refined product, researching transition metals and trace elements. All the samples were first digested with a microwave digestion system and then analyzed by a triple quadrupole (TQ) inductively coupled plasma mass spectrometer (ICP-MS-QQQ) located in a Clean Room ISO class 6. The minimum value of most of the elements (Li, Be, Na, Ca, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, As, Se, Rb, Sr) are in the wheat flour "00" type and in the wheat flour "0" type (B, Na, Mg, Al, Cu, Ag, Cd, In, Cs, Pb, Bi). On the opposite, the maximum value of these elements is found in whole wheat flour (B, Mg, K, Ca, Mn, Zn, Ga, Rb, Sr, Ba) and in the wheat flour "0" type (Na, Al, V, Cr, Fe, Co, Ni, As). Relating rare-earth elements (REE), all of them show value similar to each other and not under the detection limits thanks to the use of a TQ in the clean room. The final aim is to create a large database, with a high data bank and easily enlargeable, that could be used in future to analyze unknown flour samples and to set up traceability analysis. The purpose of this work is to find some trends of analyzed elements in function of different parameters, such as milling degree or geographical origin, also with a statistical point of view.