Yu-Hsiang Sung

Analysis of earthy and musty odors in water samples by solid-phase microextraction coupled with gas chromatography/ion trap mass spectrometry

A method for the determination of the earthy and musty odors geosmin, 2-methylisoborneol (2-MIB), 2-isobutyl-3-methoxy pyrazine (IBMP), 2-isopropyl-3-methoxy pyrazine (IPMP) and 2,4,6-trichloroanisole (2,4,6-TCA) in water by headspace solid-phase microextraction (HSSPME) combined with gas chromatography-ion trap mass spectrometry (GC-ITMS) is described. Several parameters of the extraction and desorption procedure were studied and optimized (such as types of fibers, extraction temperature, extraction time, desorption temperature, desorption time, ionic strength and elutropic strength and pH of samples). The method shows good linearity over the concentration range 1-500ngl(-1) and gives detection limits of sub-part per trillion levels for all compounds. Good precision (5.9-9.8%) is obtained using IBMP as internal standard. Finally, the method was successfully applied to analyze earthy and musty odors in tap water and lake water.

Analysis of triazine in water samples by solid-phase microextraction coupled with high-performance liquid chromatography

Solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC) for the determination of triazine is described. Carbowax/templated resin (CW/TPR, 50mum), polydimethylsiloxane/divinylbenzene (PDMS/DVB, 60mum), polydimethylsiloxane (PDMS, 100mum), and polyacrylate (PA, 85mum) fibers were evaluated for extraction of the triazines. CW/TPR and PDMS/DVB fibers were selected for further study. Several parameters of the extraction and desorption procedure were studied and optimized (such as types of fibers, desorption mode, desorption time, compositions of solvent for desorption, soaking periods and the flow rate during desorption period, extraction time, temperature, pH, and ionic strength of samples). Both CW/TPR and PDMS/DVB fibers are acceptable; a simple calibration-curve method based on simple aqueous standards can be used. The linearity of this method for analyzing standard solution has been investigated over the range 5-1000ngmL(-1) for both PDMS/DVB and CW/TPR fibers. All the correlation coefficients in the range 5-1000ngmL(-1) were better than 0.995 except Simazine and Atratone by CW/TPR fiber. The R.S.D.s range from 4.4% to 8.8 % (PDMS/DVB fiber) and from 2.4% to 7.2% (CW/TPR fiber). Method-detection limits (MDL) are in the range 1.2-2.6 and 2.8-3.4ngmL(-1) for the two fibers. These methods were applied to the determination of trazines in environmental water samples (lake water).

Solid-phase microextraction coupled with high-performance liquid chromatography for the determination of phenylurea herbicides in aqueous samples

Solid-phase microextraction coupled with high-performance liquid chromatography was successfully applied to the analysis of nine phenylurea herbicides (metoxuron, monuron, chlorotoluron, isoproturon, monolinuron, metobromuron, buturon, linuron, and chlorbromuron). Polydimethylsiloxane-divinylbenzene (PDMS-DVB, 60 microm) and Carbowax-templated resin (CW-TPR, 50 microm) fibers were selected from four commercial fibers for further study because of their better extraction efficiencies. The parameters of the desorption procedure were studied and optimized. The effects of the properties of analytes and fiber coatings, carryover, duration and temperature of absorption, pH, organic solvent and ionic strength of samples were also investigated. External calibration with an aqueous standard can be used for the analysis of environmental samples (lake water) using either PDMS-DVB or CW-TPR fibers. Good precisions (1.0-5.9%) are achieved for this method, and the detection limits are at the level of 0.5-5.1 ng/ml.

Use of Muromac A-1 chelating resin for determination of copper and molybdenum in seawater by atomic absorption with on-line preconcentration

Abstract Muromac A-1 chelating resin is used to preconcentrate trace metals (copper and molybdenum) in seawater. A miniature column (4–7 μl) packed with resin and a home-made automatic on-line preconcentration system for graphite furnance atomic absorption spectrometry (GFAAS) were used. This preconcentration system was modified from a Perkin-Elmer AS-40 autosampler by mounting a Muromac A-1 microcolumn near the tip of the autosampler capillary. The preconcentration procedure was performed by using a four-way distribution valve and a programmable controller. A sample volume of only 20–200 μl was required for determining copper and molybdenum in seawater. The calibration graph method was used; the detection limits for copper and molybdenum were 0.05 ppb and 0.25 ppb respectively. The sample throughput was 18–26 h−1. The accuracy of the method was confirmed by the analysis of certified reference saline waters.

Automated On-line Preconcentration System for Electrothermal AtomicAbsorption Spectrometry for the Determination of Copper and Molybdenum inSea-water

A flow injection accessory for electrothermal atomic absorption spectrometry was developed. The performance of the on-line preconcentration system was tested by determining Cu and Mo in sea-water. Calibration graphs constructed from the preconcentration of standards in 0.2% HNO 3 solution were used. On-line preconcentration is computer-controlled. A miniature Muromac A-1 resin column was inserted at the tip of the AS-60 autosampler arm. A modification of the AS-60 autosampler in the tubing line and circuit allowed either flow of the sample through the column or operation of the autosampler in the normal mode. Retention of the metal ions as complexes on the microcolumn was achieved by using Muromac A-1 as the chelating resin; 20% v/v HNO 3 was then used for elution. With a 198.6 µl sample loop, the throughput is 14 samples h -1 . Detection limits are 0.009 µg l -1 for Cu (606.9 µl sample loop) and 0.06 µg l -1 for Mo (50 µl sample loop and repeated four times). The accuracy of the method was confirmed by the analysis of certified reference saline waters.

Determination of benzene derivatives in water by solid-phase microextraction

A solid-phase microextraction (SPME) technique was successfully applied to the analysis of benzene derivatives (aniline, m-nitroaniline, o- and p-cresol, o-, m- and p-dinitrobenzene) in water. Two kinds of fibre (poly(dimethylsiloxane) (PDMS) and polyacrylate (PARL) fibres) were used and compared. The effects of the structure and physical properties of the analytes, duration of absorption and desorption, temperature of absorption, storage time, pH, ionic strength and elutropic strength of samples were investigated. Much higher sensitivity and lower detection limits were achieved using a PARL fibre than those using a PDMS fibre. The detection limits were less than 5 ng/ml for most of the analytes, except for aniline (16 ng/ml) and o-dinitrobenzene (7 ng/ml).

Direct and simultaneous determination of arsenic, manganese, cobalt and nickel in urine with a multielement graphite furnace atomic absorption spectrometer.

A simple method was developed for the direct and simultaneous determination of arsenic (As), manganese (Mn), cobalt (Co), and nickel (Ni) in urine by a multi-element graphite furnace atomic absorption spectrometer (Perkin-Elmer SIMAA 6000) equipped with the transversely heated graphite atomizer and longitudinal Zeeman-effect background correction. Pd was used as the chemical modifier along with either the internal furnace gas or a internal furnace gas containing hydrogen and a double stage pyrolysis process. A standard reference material (SRM) of Seronormtrade mark Trace Elements in urine was used to confirm the accuracy of the method. The optimum conditions for the analysis of urine samples are pyrolysis at 1350 degrees C (using 5% H(2) v/v in Ar as the inter furnace gas during the first pyrolysis stage and pure Ar during the second pyrolysis stage) and atomization at 2100 degrees C. The use of Ar and matrix-free standards resulted in concentrations for all the analytes within 85% (As) to 110% (Ni) of the certified values. The recovery for As was improved when mixture of 5% H(2) and 95% Ar (v/v) internal furnace gas was applied during the first step of a two-stage pyrolysis at 1350 degrees C, and the found values of the analytes were within 91-110% of the certified value. The recoveries for real urine samples were in the range 88-95% for these four elements. The detection limits were 0.78mugl(-1) for As, 0.054mugl(-1) for Mn, 0.22mugl(-1) for Co, and 0.35mugl(-1) for Ni. The upper limits of the linear calibration curve are 60mugl(-1) (As); 12mugl(-1) (Mn); 12mugl(-1) (Co) and 25mugl(-1) (Ni), respectively. The relative standard deviations (R.S.D.s) for the analysis of SRM were 2% or less. The R.S.D.s of a real urine sample are 1.6% (As), 6.3% (Mn), 7.0% (Ni) and 8.0% (Co), respectively.

Simultaneous determination of manganese, iron and cobalt in copper with a multi-element graphite furnace atomic absorption spectrometer

Abstract A simple method was developed for the determination of trace metals (Mn, Fe and Co) in copper simultaneously using a multi-element graphite furnace atomic absorption spectrometer (Perkin-Elmer SIMAA6000) equipped with a transversely heated graphite atomizer. Copper was dissolved in nitric acid before analysis using a microwave digestion system. Pd(NO 3 ) 2 with the special gas (5% H 2 in Ar) was used as the chemical modifier. The accuracy of the method was confirmed by the analysis of certified reference copper (CRM#075). The interferences were removed effectively, so that a calibration curve method based on simple aqueous standards could be used. The analyzed values were in the range of 96.6% (Mn) to 113% (Co) of the certified values. The relative standard deviations for the simultaneous determination of Mn (6.5 μg/l), Fe(18 μg/l) and Co(5 μg/l) in solution from copper are 2.4–3.5% and the detection limits were 0.17 μg/g for Mn, 0.50 μg/g for Fe and 0.30 μg/g for Co.