Authors:Chu-Fang Wang, Cheng-Hsiung Ke, and Jenq-Yann Yang
Tea has been one of the most popular simulating beverages which is both heavily produced and consumed in Taiwan. The determination of minor or trace elements in drinking tea and tea leaves is therefore important for estimating the daily intake of Taiwanese considered as a safety indicator. In order to accurately and precisely determine the concentrations of trace elements in samples, several analytical methods such as AAS, NAA and ICP-AES are suggested. This paper attempts to utilize all three methods to determine the concentrations of minor or trace elements in different types of tea leaves and the extracts percolated from them. The influence of fermentation processes on the concentration levels of minor or trace elements in tea samples is investigated. Because only free metal ions are bioavailable for the human body, it is necessary to determine their concentrations in drinking tea. The dissolution of trace elements in drinking tea is therefore studied by simulating the common Chinese style of tea percolation. Concentrations of thirteen elements including Zn, Mn, Ca, Cu, Ni, Al, K, Mg, Cd, Pb, Na, Co and Sc are determined.
Authors:Chu-Fang Wang, E. Chang, and Pen-Chi Chiang
Multielement determination of airbone particulates collected on PTFE-membrane filters by XRF, and possibility of using this technique in Receptor Model analysis were investigated. In order to keep the background interference as low as possible, special emphasis was therefore laid on the setup of optimized analytical procedures for XRF measurement. An intercomparison between INAA and XRF methods was performed by analyzing the same filter samples.
Authors:Chu-Fang Wang, Ming-Jenq Duo, E. Chang, and Jenq Yang
The concentration of certain toxic and essential elements in various raw materials of Chinese herbs and scientific Chinese medicine were determined by atomic absorption spectrometry (AAS) and instrumental neutron activation analysis (INAA). Correlation of these elements as they exist in the raw materials and in the prescription of medicine were investigated and the approximate intake of elements by patients were estimated. Values of elements determined both by ASS and INAA presented excellent agreement. The ranges of elemental concentrations were found to vary from 104 to 10–1 mg/kg in different kinds of herbs. All herbs exhibit extraordinary enrichment capabilities from the environment for elements such as Mn, Zn, Ca, K, Mg, Cd, Cu, Pb and As. Higher contents of Cd, Pb and As in herbs may be attributed to the uptake of these elements from polluted soil due to industrial and antropogenic activities. It was found that commercial scientific Chinese medicine, SCDBT, contains more elemental concentrations than that of herbs used in the prescription, which may indicate that possible contamination could be caused by unknown ingredients added in the process. A much higher toxic elemental content, such as Pb, Cd and As, has been found in CFH and the daily intake of these elements by the patient will exceed the PTDI values.
Authors:Chu-Fang Wang, Fang-Huang Tu, Su-Ling Jeng, and Ching-Jer Chin
This study reports the analysis of Si in airborne particulate matter by laser ablation inductively coupled plasma mass spectrometry
(LA-ICP-MS) as well as X-ray fluorescence (XRF). It was found that Si concentration in airborne particulates collected on
PTFE-membrane filters could be accurately determined with a laser beam operated at 160 mJ free running mode, 6.5 mm defocusing
distance and 0.8 l/min carrier gas flow rate during the LA-ICP-MS measurement. Standard filters prepared by NIST SRM 1648
urban particulates were used for both XRF and LA-ICP-MS not only to establish the calibration curves of Si, but also to examine
the proposed method's effectiveness. The capability of applying both methods for natural sample analysis was also examined.
Particulate loaded filter samples collected from a heavily polluted metropolitan area of Kaoshiung, Taiwan were initially
measured by XRF, then by LA-ICP-MS. An intercomparison between them was thus performed. As a result, both XRF and LA-ICP-MS
proved to be the valid analytical methods for directly determining Si concentrations in airborne particulates on PTFE membrane
Authors:Chu-Fang Wang, Ming-Chen Yuan, Cheng-Yuan Chang, and Huang Su-Chen
Direct analysis of airborne particulate matter collected on PTFE-membrane filters was performed using synchrotron radiation
X-ray fluorescence (SRXRF). Standard filter samples prepared in the laboratory were utilized to evaluate the setup performance
as well as the capability of the proposed method. The influence of experimental parameters including the beam size and sample-to-detector
distance were thoroughly examined. A total of 10 elements on the filter can be determined. It was found that the optimum detection
efficiency for the system can be achieved if using a 3 mm´3 mm beam size as well as a 7 cm sample-to-detector distance with
a two-step measurement procedure with photon energy less than 7 keV and 14 keV, respectively.