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Abstract
A systematic non-destructive determination of eighteen trace elements (F, Na, Cl, Sc, Mn, Zn, Br, Sr, I, Ba, La, Ce, Sm, Eu, Tb, Yb, Th and U) in carbonate samples by thermal neutron activation analysis was developed. Three 0.2–0.5g samples were irradiated for 15 sec (in the case of determination of F), for 3 min (in the case of Na, Cl, Mn, Sr and I) and for 60 hrs (in the case of Sc, Zn, Br, Ba, La, Ce, Sm, Eu, Tb, Yb, Th and U) in the TRIGA MARK II Reactor at a thermal neutron flux of 5·1011 n·cm−2·sec−1 (15 sec and 3 min irradiation) and 1.5·1012n·cm−2·sec−1 (60 hrs irradiation), respectively. According to the half life of the nuclides formed, the activities were measured with a Ge(Li) spectrometer as follows,20F∶15 sec counting after 20–25 sec cooling,24Na,38Cl,56Mn,87mSr and128I∶600 sec couting after 30–120 min cooling,82Br,140La,153Sm,175Yb and239Np (daughter of239U)∶3000 sec counting after 1 week cooling,46Sc,65Zn,131Ba,141Ce,152Eu,160Tb and233Pa (daughter of233Th)∶5000 sec counting after 1 month cooling. The errors due to the fluctuation of the neutron flux and the counting geometry were minimized by the use of calcium determined previously with EDTA-titration as an internal standard. The interferences from24Mg(n, p)24Na and235U(n, fission) reactions were corrected by the activities produced by the reactions in unit weight of magnesium and uranium, and their concentrations in samples measured experimentally. The data of Na, Mn, Zn and Sr were compared with the results obtained by atomic absorption analysis.
23.44 f 15.46 Physical mixture (PM) 12.11 c 0.28 d 62.42 e 23.18 f 15
mass: 14-F + , 15-CH 3 + , 17-OH + , 18-H 2 O + , 28-CO + , 30-NO + , 31-P +, 38-F 2 + , 44-CO 2 + , 46-NO 2 + , 64-SO 2 + and 142-P 2 O 5 + . Approximately 4 mg of powdered sample, and reference substance (α-Al 2 O 3 , Merck) were heated (the rate 10
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. https://www.ecfr.gov/cgi-bin/text-idx?SID=46e0f15c31b8f5b1c0a348eac9f380e5&mc=true&node=se40.24.180_141&rgn=div8 . 12. Commission regulation (EC) No. 178/2006. Amending Regulation (EC) No. 396/2005 of the European
), significant increase in a* ( F = 15.106) and decrease in hue angle (data not shown in figures) values ( F = 10.578) were observed as normal postharvest ripening in the case of the at 10 °C (control) stored samples compared to the results of CI inducing
