title: Determination of the presence of hyaluronic acid in preparations containing amino acids: the molecular weight characterization.
abstract: Several pharmaceutical preparations contain hyaluronic acid in the presence of a large variety of low molecular weight charged molecules like amino acids. In these mixtures, it is particularly difficult to determine the concentration and the molecular weight of the hyaluronic acid fragments. In fact zwitterionic compounds in high concentration behave by masking the hyaluronic acid due to the electrostatic interactions between amino acids and hyaluronic acid. In such conditions the common colorimetric test of the hyaluronic acid determination appears ineffective and in the (1)H NMR spectra the peaks of the polymer disappear completely. By a simple separation procedure the presence of hyaluronic acid was revealed by the DMAB test and (1)H NMR while its average molecular weight in the final product was determined by DOSY NMR spectroscopy alone. The latter determination is very important due to the healthy effects of some sizes of this polymer's fragments.
authors: Department of Chemical Sciences and Technology, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy; Cooperativa di Ricerca Finalizzata, Via della Ricerca Scientifica 1, 00133 Rome, Italy. Electronic address: alessia.bellomaria@uniroma2.it.
authors: A
authors: A
authors: Bellomaria
authors: Department of Chemical Sciences and Technology, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy. Electronic address: ridvan.nepravishta@uniroma2.it.
authors: R
authors: R
authors: Nepravishta
authors: Cooperativa di Ricerca Finalizzata, Via della Ricerca Scientifica 1, 00133 Rome, Italy. Electronic address: uranio.mazzanti@gmail.com.
authors: U
authors: U
authors: Mazzanti
authors: Italfarmacia srl, Via Tor Sapienza, 8, Rome, Italy. Electronic address: marchetti_mario@libero.it.
authors: M
authors: M
authors: Marchetti
authors: Italfarmacia srl, Via Tor Sapienza, 8, Rome, Italy. Electronic address: regulatoria@libero.it.
authors: P
authors: P
authors: Piccioli
authors: Department of Chemical Sciences and Technology, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy. Electronic address: paci@uniroma2.it.
authors: M
authors: M
authors: Paci
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D006820:Hyaluronic Acid / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D055672:Static Electricity
chemical_list: D000596:Amino Acids; D006820:Hyaluronic Acid
keywords: DOSY; Hyaluronic acid; NMR spectroscopy; Separation