Scholarly record

BEHAVIOUR OF SOME CLINOPTILOLITE RICH NATURAL ZEOLITES FROM ROMANIA IN SIMULATED BIOLOGICAL FLUIDS

Oana Cadar

Abstract

The use of synthetic or natural zeolites in food processing and medical (drug or drug support systems, nutritive supplements) applications also depends on their behavior under digestive conditions. This study aims to investigate the changes in the crystalline structure of natural zeolites in simulated in vitro digestion conditions and the interaction with simulated body fluid (SBF, pH=7.40) and simulated gastric fluid (SGF, pH=1.20). The different pH of used simulated biological fluids may result in interactions between zeolite and media leading to changes of structural and chemical composition of zeolite. The used natural zeolite originated from a deposit near Chilioara, Salaj County, Romania. Different particle size (<0.5 and 0.5-1.25 nm), zeolite mass / SBF or SGF volume ratios (0.5, 1.0, 2.5 and 5 mg/mL) and exposure times (1, 3, 5 and 7 days) were used in this study. X-ray diffraction (XRD) analysis indicated that the crystalline structure of natural zeolites was not significantly affected after immersion in both simulated biological fluids up to 7 days. In all cases, no significant variations of pH values were observed. The amount of Na, K, Ca, Mg, Fe, Al, Si and P released in SBF and SGF was investigated by inductively coupled plasma optical emission spectrometry (ICP-OES). In SBF, Fe and Al concentrations were below the detection limits. The Ca and Mg concentrations increased with the zeolite mass/SBF volume ratio and exposure time, while Na, K and P concentrations decreased. In SGF, all concentrations increased considerably. In all cases, better results were obtained for smaller particle size (<0.5 nm) and lower pH, which might be effective on slight dissolution of investigated elements. In both simulated biological fluids, noticeable amounts of Si were detected and no significant variations of concentration were remarked, probably due to the high stability of clinoptilolite rich natural zeolites. This study offers valuable information for the use of natural zeolites in food processing and medicine (clinical research and alternative therapies).

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