National Repository of Grey Literature 3 records found  Search took 0.00 seconds. 
Stability of the sodium content in selected botanical reference materials
Kameník, Jan ; Kučera, Jan ; Borovička, Jan ; Havránek, Vladimír
Sodium mass fractions in NIST standard reference materials (SRM) SRM 1547 Peach Leaves and SRM 1515 Apple leaves determined by INAA in our laboratory in recent years has been higher than the certified values. Similarly, increased values were published for SRM 1547 by several other laboratories. The increased Na mass fractions was found also for freshly opened SRM 1547 bottle and for material originating from a different lab. Increased Na mass fractions were confirmed by ICP-MS analysis of both materials. Analysis of archived samples revealed that sodium mass fraction in materials stored in polyethylene capsules is in agreement with the certified values. The sodium content in the glass of SRM 1547 bottle was roughly 10 %. Direct measurement of the Na depth profile by micro-PIXE was not indicative whether Na is released, i.g., by a glass corrosion due to residual humidity in the botanical material. However, a model experiment with freshly prepared and pulverized peach leaves demonstrated that such a scenario is possible for leaf-based materials. Although the study was focused on two NIST materials, the process is possible for any material with rather low Na content.
Provenancing of drugs based on their elemental composition determined by Neutron Activation Analysis - Feasibility Study
Kučera, Jan ; Kameník, Jan ; Sabol, J. ; Šesták, B. ; Kolář, P. ; Roman, M.
We analyzed five samples of heroine and five samples of cocaine seized in the Czech Repulic using instrumental neutron activation analysis (INAA). In the heroine speciments, we determined 16 trace elements in at least one of the samples analyzed, in the cocaine speciment, 9 trace elements could be determined. We have found remarkable differences, up to several orders of magnitude, in contents of the elements Na, Cl, Zna and Br, especially in the heroine samples. The accuracy of INAA results was proved by simultaneous analysis of a certified reference material NIST SRM 1547 Peach Leaves. The results of trace element determination in heroine samples are compard with those published by autors from abroad. The results obtained show a high potential of INAA for the drug elemental characteriaztion aimed at determination of their provenance, procedures used for their manufacturing and purification and cutting for the end users. The results achieved also suggest that it is desirable to analyze more samples with the final aim of establishing a database of elemental composition of drugs seized in the Czech Republic, which could possibly be extended later, in cooperation with foreign drug abuse and police bodies, at the international level.
Impact of cryogenic grinding on iodine homogeneity in NIST SRM 1548a Typical Diet
Kameník, Jan ; Kučera, Jan
The reference material NIST SRM 1548a Typical Diet has a certified iodine mass fraction of 0.759±0.103 mg kg-1. The expanded uncertainty is rather large (relative value 13.6 %), thus the material does not provide strict requirements for quality control results. Milling of NIST SRM 1548a at the temperature of liquid nitrogen yielded free-flowing material. Iodine mass fraction in the original and cryo-ground materials was determined by epithermal neutron activation analysis (ENAA) and radiochemical neutron activation analysis (RNAA). The average and standard deviation from both methods was 0.73±0.03 mg kg-1 (20 values). The determined mass fraction was in a close agreement with the certified value of NIST SRM 1548a, thus iodine total content was not influenced by the milling procedure. In comparison to iodine mass fraction determined in the original NIST SRM 1548a 0.72±0.07 mg kg-1 (average ± standard deviation, 14 values), the standard deviation for cryo-ground material was considerably lower. The prepared quality control material sets up more stringent requirements on the validation and quality control procedures of the measurement of iodine mass fraction in such a composite food matrices. We believe that the iodine random inhomogeneity in the original NIST SRM 1548a is due to insufficient mixing of some iodine-rich component in the complex food matrices. Milling at the temperature of liquid nitrogen offers an effective option for production of future reference materials of this kind.

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5 KAMENÍK, Josef
2 Kameník, Jaroslav
5 Kameník, Josef
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