Ji Yeon Choi

Analysis of minor and trace elements in milk and yogurts by inductively coupled plasma-mass spectrometry (ICP-MS)

This study aimed at analysing the content of 22 minor and trace elements in milk and yogurts from South Korea, using inductively coupled plasma-mass spectrometry (ICP-MS), after digestion using heating block. The analytical method was validated by detection limits, precision, accuracy and recovery experiments, obtaining satisfactory results in all cases. Results of both minor and trace elements were found mostly similar in all varieties of milk and yogurts studied. Copper and manganese were comparatively high in fruit mixed yogurts, while selenium was high in milk samples. The overall concentrations of minor elements were found to have good nutritional values in accordance to RDA. Zn showed the highest concentration, followed by Rb, Se, Sr and Cr. The level of toxic trace elements, including As, Cd and Pb were very low and did not pose any threat to consumers.

Method validation for simultaneous determination of chromium, molybdenum and selenium in infant formulas by ICP-OES and ICP-MS

This study aimed to validate the analytical method for simultaneous determination of chromium (Cr), molybdenum (Mo), and selenium (Se) in infant formulas available in South Korea. Various digestion methods of dry-ashing, wet-digestion and microwave were evaluated for samples preparation and both inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) were compared for analysis. The analytical techniques were validated by detection limits, precision, accuracy and recovery experiments. Results showed that wet-digestion and microwave methods were giving satisfactory results for sample preparation, while ICP-MS was found more sensitive and effective technique than ICP-OES. The recovery (%) of Se, Mo and Cr by ICP-OES were 40.9, 109.4 and 0, compared to 99.1, 98.7 and 98.4, respectively by ICP-MS. The contents of Cr, Mo and Se in infant formulas by ICP-MS were found in good nutritional values in accordance to nutrient standards for infant formulas CODEX values.

Determination of toxic heavy metals and speciation of arsenic in seaweeds from South Korea

This study aimed at determining the levels of toxic heavy metals including As, Pb, Cd, Al, Hg and As species, such as, As-III, As-V, MMA, DMA, AsB, and AsC in various edible species of seaweeds from South Korea. ICP-MS was used for determination of As, Pb and Cd, ICP-OES was used for Al, DMA was used for Hg, and LC-ICP-MS was used for As speciation. The analytical methods were validated by linearity, detection limits, precision, accuracy and recovery experiments, obtaining satisfactory results in all cases. From the results toxic heavy metals were found in the decreasing order of: Al>As>Pb-Cd>Hg. Generally concentrations of all analysed heavy metals and both organic and inorganic species of As were very low compared to PTWIs specified by JECFA and EC. Their contribution to the overall intake by the subject seafoods was found very low and thus would not pose any threat to consumers.

Determination of minor and trace elements in aromatic spices by micro-wave assisted digestion and inductively coupled plasma-mass spectrometry

This study aimed at analyzing the concentrations of 23 minor and trace elements in aromatic spices by inductively coupled plasma-mass spectrometry (ICP-MS), after wet digestion by microwave system. The analytical method was validated by linearity, detection limits, precision, accuracy and recovery experiments, obtaining satisfactory values in all cases. Results indicated the presence of variable amounts of both minor and trace elements in the selected aromatic spices. Manganese was high in cinnamon (879.8 μg/g) followed by cardamom (758.1 μg/g) and clove (649.9 μg/g), strontium and zinc were high in ajwain (489.9 μg/g and 84.95 μg/g, respectively), while copper was high in mango powder (77.68 μg/g). On the whole some of the minor and essential trace elements were found to have good nutritional contribution in accordance to RDA. The levels of toxic trace elements, including As, Cd, and Pb were very low and did not found to pose any threat to consumers.

Determination of toxic heavy metals in Echinodermata and Chordata species from South Korea

This study aimed at analysing concentrations of heavy metals including arsenic, lead, cadmium, aluminium and mercury in commonly consumed seafood species belonging to Echinodermata (Anthocidaris crassispina and Stichopus japonicus) and Chordata (Halocynthia roretzi and Styela plicata). The samples were digested by a microwave system and analysed for As, Cd and Pb by inductively coupled plasma mass spectrometer, for Al by inductively coupled plasma-optical emission spectrometer and Hg by Direct Mercury Analyser. The analytical method was validated by determining sensitivity, linearity, precision, spiking recoveries and analysis of the Standard Reference Material (SRM) NIST 1566-b, an Oyster Tissue. Results showed considerably higher accumulation of Al and As in analysed samples, compared to Pb and Cd, while Hg had the lowest contamination. On comparison, the obtained results with the recommended standards by the Food and Agriculture Organization, European Commission and Ministry of Food and Drug Safety of Korea, it was concluded that the analysed seafoods were safe and thus would not pose a threat to consumers.

Speciation of Arsenic in Rice by High-Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

ABSTRACT This study reports the optimization and validation of arsenic speciation of rice. Total arsenic was determined by inductively coupled plasma mass spectrometry; arsenite, arsenate, monomethylarsonic acid, and dimethyarsinic acid were quantified by high-performance liquid chromatography–inductively coupled plasma mass spectrometry. Methods using nitric acid and malonic acid were validated at various extraction conditions and mobile phase systems. The linear dynamic range, limit of detection, precision, fortification, and analysis of a white rice flour certified reference material (CRM-7503-a) were evaluated for quality assurance. The use of 5 mM malonic acid for extraction with an isocratic mobile phase was optimized for extraction time and temperature and employed for arsenic speciation in rice. The concentrations of total arsenic, arsenite, arsenate, monomethylarsonic acid, and dimethyarsinic acid were low compared to the provisional tolerable weekly intakes specified by the Food and Agriculture Organization/World Health Organization Joint Expert Committee on food additives and European food safety authority and thus do not pose a threat to consumers.

Elemental profiling and geographical differentiation of Ethiopian coffee samples through inductively coupled plasma-optical emission spectroscopy (ICP-OES), ICP-mass spectrometry (ICP-MS) and direct mercury analyzer (DMA).

This study was aimed to establish the elemental profiling and provenance of coffee samples collected from eleven major coffee producing regions of Ethiopia. A total of 129 samples were analyzed for forty-five elements using inductively coupled plasma (ICP)-optical emission spectroscopy (OES), ICP-mass spectrometry (MS) and direct mercury analyzer (DMA). Among the macro elements, K showed the highest levels whereas Fe was found to have the lowest concentration values. In all the samples, Ca, K, Mg, P and S contents were statistically significant (p<0.05). Micro elements showed the concentrations order of: Mn>Cu>Sr>Zn>Rb>Ni>B. Contents of the trace elements were lower than the permissible standard values. Inter-regions differentiation by cluster analysis (CA), linear discriminant analysis (LDA) and principal component analysis (PCA) showed that micro and trace elements are the best chemical descriptors of the analyzed coffee samples.

Determination of Toxic Metals in Cephalopods from South Korea

ABSTRACT This study determined lead, cadmium, arsenic, mercury, and aluminum in six cephalopod species commercially available to consumers in South Korea. The samples were prepared by microwave-assisted acid digestion and analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) for As, Pb, and Cd and inductively coupled plasma-optical emission spectrometry (ICP-OES) for Al. Hg was determined by a direct mercury analyzer with furnace-gold amalgation. Linearity, sensitivity, precision, accuracy, and recovery measurements were performed for validation. The analytical results showed that the average concentrations of metals were in decreasing order of Al>As>Cd>Pb>Hg. Paroctopus dofleini contained relatively high concentrations of Pb (0.43 mg/kg) and As (14.6 mg/kg); Todarodes pacificus contained high Cd (15.0 mg/kg), whereas Al (40.4 mg/kg) was highest in Loligo beka. Using the guidelines specified by Korean Food Regulations, the United Nations, and the European Commission, we found that the concentrations of these metals in the cephalopods studied were low and did not pose any threat to consumers.

Geographical origin authentication of pork using multi-element and multivariate data analyses.

In the recent years, consumers have become increasingly concerned about the authenticity and labeling claims associated with meat and meat based products. In this study, investigating geographical origin authenticity of pork, 323 samples of pork belly were collected from Korea, USA, Germany, Austria, Netherlands and Belgium. These were analyzed for twenty-nine macro and trace elements using inductively coupled plasma-optical emission spectroscopy (ICP-OES), and ICP-mass spectrometry (MS). The applied analytical techniques were validated by quality assurance parameters in which the values of correlation coefficient, limits of detection and quantification, precision, and spiking recovery confirmed that the methods were well efficient and in accordance to the criteria set by the Association of Official Analytical Chemists (AOAC) for metals analysis. From the results of multivariate analyses, it was found that the trace elements are promising constituents which could be used to accurately determine the inter-continental provenance of pork.

Determination of volatile organic compounds, catechins, caffeine and theanine in Jukro tea at three growth stages by chromatographic and spectrometric methods.

Tea contains characteristic volatile organic compounds, polyphenols, caffeine and catechins, and is therefore among the most widely consumed beverages all over the world. In this study, fresh Jukro tea leaves collected from Damyang-gun (Jeollanam-do) at 40, 60 and 90day growth stages, were semi-fermented. The volatile organic compounds (VOCs) were extracted by simultaneous distillation-solvent extraction (SDE) and analyzed by gas chromatography/mass spectrometry (GC/MS). Catechins, caffeine and theanine were analyzed by high performance liquid chromatography (HPLC). A total of 159 VOCs were identified in the analyzed Jukro tea leaves. Comparatively, the increase in the concentrations of VOCs was high in 60day leaves. The content of catechins increased along the three growth stages, whereas caffeine, compared to 90day leaves, was higher for 40 and 60day leaves. Based on the results, the 60day leaves were found to be the most suitable and useful for making semi-fermented Jukro tea.