Robust Z-score Research Articles

Mineral Compositions of Eight Common Spices

Eight common spices have been studied for their mineral compositions using inductively coupled plasma optical emission spectrometry (ICP-OES) after acid digestion. The seeds of the following spices were used for analysis: coriander, cumin, anise, nigella, mustard, carum, black pepper, and fenugreek. Average elemental compositions of spices seeds were reported using robust Z-score statistic. Fourteen elements were considered, which include heavy metals like iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), nickel (Ni), molybdenum (Mo), lead (Pb), and chromium (Cr), alkaline earth metals like calcium (Ca) and magnesium (Mg), lighter element like aluminum (Al) and non-metals like silicon (Si) and phosphorus (P). A very strong linear correlation exists between Fe and Al contents in the spices. Zinc also correlates well with iron. This study provides a reliable account of the endogenic concentrations of a number of common elements including heavy metals present in these spices.

A proficiency testing of electromagnetic radiated emission measurements

A proficiency testing is carried out for electromagnetic radiated emission(RE) measurements in the frequency range of 30–1000 MHz. A sphericaldipole radiator (SDR) is employed as a reference emitting source. Usingthe SDR, the RE measurements are taken for horizontal and verticalpolarizations at 12 open area test sites and the measurement distanceis 10 m. To evaluate the proficiency of each test laboratory, the robustZ score andEn ratio methods are used.In order to use the Enratio method, the measurement uncertainty of each test laboratory is evaluatedin accordance with the International Organization for Standardizationguide to the expression of uncertainty in measurement. Results show thatdecision on a proficiency testing depends on the evaluation method used.