A certified reference material (CRM) for the analysis of nutrient elements in an edible mushroom (Ganoderma lyceum) powder has been developed (KRISS CRM 108-10-011). The mass fractions of calcium (Ca), iron (Fe), and zinc (Zn) were measured by isotope dilution inductively coupled plasma mass spectrometry (ID ICP/MS). To dissolve the fungi cell wall of mushroom consisted of chitin fibers, sample preparation method by single reaction chamber type microwave-assisted acid digestion with acid mixtures was optimized. The mean measurement results obtained from 12 sample bottles were used to assign as the certified values for the CRM and the between-bottle homogeneities were evaluated from the relative standard deviations. The certified values were metrologically traceable to the definition of the kilogram in the International System of Units (SI). This CRM is expected to be used for validation of analytical methods or quality control of measurement results in analytical lab-oratories when they determine the mass fractions of elements in mushroom or other similar samples.
A method based on flow injection-isotope dilution-cold vapor-inductively coupled plasma mass spectrometry (FI-IDCV-ICP/MS) has been applied to determine trace level of mercury in fly ash. 200Hg isotopic spike was added to 0.25 g of BCR176Rfly ash and then decomposed by microwave digestion procedure with acid mixture A (8 mL HNO3 + 2 mLHCl + 2 mL HF) and acid mixture B (8 mL HNO3 + 2 mL HClO4 + 2 mL HF) for applying IDMS. Mercury cold vapor was generatedby using reductant solution of 0.2% (w/w) NaBH4 and 0.05% (w/w) NaOH. The measurements of n(200Hg)/n(202Hg) isotoperatio was made using a quadrupole ICP/MS system. The accuracy in this method was verified by the analysis of certified referencematerial (CRM) of fly ash (BCR 176R). The indicative value of Hg in BCR 176R fly ash was 1.60 ± 0.23 mg/kg (k = 2). The determinedvalues of Hg in BCR 176R fly ash by the method of FI-CV-ID-ICP/MS described in this paper were 1.60 ± 0.24 mg/kg(k = 3.18) and the analysis results were in well agreement with the indicative value within the range of uncertainty.
A certified reference material (CRM) for the analysis of inorganic nutrients in nutritional supplements has been developed. Accurate mass fractions of chromium (Cr), iron (Fe), copper (Cu), and zinc (Zn) were determined by isotope dilution inductively coupled plasma mass spectrometry (ID ICP/MS). The measurement results were used to assign certified values for the CRM, which were metrologically traceable to the definitions of the measurement units in the International System of Units (SI). Production of a candidate reference material (RM) and the certification processes are summarized. Each nutrient in the CRM showed good homogeneity, which was estimated using relative standard deviations of the measurement results of twelve bottles in a batch. This CRM is expected to be an important reference to improve reliability and comparability of nutrient analy- ses in nutritional supplements and related samples in analytical laboratories.