| Summary: | 碩士 === 國立中山大學 === 化學系研究所 === 102 === In the first study, speciation of arsenic in seaweeds was carried out using ion chromatography (IC) for separation and inductively coupled mass spectrometry (ICP-MS) for detection. The arsenic species studied were arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobeta-
ine (AsB), arsenocholine (AsC), OH-arsenoribose (OH-AsR), PO4-arsenoribose (PO4- AsR) , SO3H-arsenoribose (SO3H - AsR), and trialkylarsonioribosides (Trialkyl-AsR). Chromatographic separation of all the species was achieved in <19 min in gradient elution mode using (NH4)2CO3 at pH 8.7. Since there was not standard of arsenosugar, in the experiment used extraction of Laminaria japonica Areschoug spiked [As(III)], [As(V)], MMA, DMA, AsB, AsC. The outlet of the IC column was directly connected to the nebulizer of ICP-MS for the determination of arsenic. The speciation of arsenic has been carried out in several seaweed samples. A microwave-assisted extraction method was used for the extraction of arsenic species from seaweed samples. With a mixture of mobile phase A and methanol as extractant, the extraction efficiency was >73%, and the recoveries from spiked samples were in the range of 93−109%. The unknown compounds detected in different seaweeds were identified by coupling IC directly with electrospray ionization−mass spectrometry (ESI-MS). Four arsenosugars and tetramethylarsonium ion (TMA) were identified in different seaweeds. A fat-
soluble arsenolipid compound was identified in the extract of certified reference material BCR-279 Ulva lactuca when 1% HNO3 was used as the extractant.
Second study, A HPLC separation procedure has been developed for the specia-
tion of Cr(III), Cr(VI) in wine and diabetic supplement drinks samples. The species were separated on a reversed phase column (C8) in gradient elution mode. The mobile phase consisting of EDTA and TBAP in methanol at pH 6.9, yielded well resolved chromatograms of all the species within 2 min. The analyses were carried out using dynamic reaction cell inductively coupled plasma-mass spectrometer (DRC-ICP-MS). The DRC conditions have also been optimized to obtained interference free measure-
ments of 52Cr+ and 53Cr+, which were otherwise interfered by: 35Cl16O1H+, 35Cl17O+, 40Ar12C+ on 52Cr+; and 37Cl16O+, 40Ar13C+, 40Ar12C1H+ on 53Cr+. The detection limits of the procedure were 0.052 ng 52Cr ml-1 and 0.054 ng 53Cr ml-1. The accuracy of the method has been validated by comparing the sum of the concentrations obtained for individual species with total concentration of the elements in NRCC SLRS-4 River Water. The method has also been applied on several real samples, included environmental water, wine and supplement drinks, in which case the comparison total chromium concentration. Supplement drinks has been made with total concentrations determined after complete dissolution of the samples. The species were separated by HPLC-DRC-ICP-MS in appropriate dilute.
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