• Analytical Science and Technology
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• v.8 no.4
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• pp.435-442
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• 1995

A matrix modification was studied for the determination of trace bismuth in water samples by graphite furnace atomic absorption spectrophotometry. The type and quantity of modifiers as well as the use of auxiliary modifiers were investigated to realize the efficient modification. Palladium was chosen as a single modifier. By the addition of palladium($5{\mu}g/mL$) to 100 ng/mL bismuth solution, the temperatures could be raised from $500^{\circ}C$ to $1,300^{\circ}C$ for the charring and from $2,000^{\circ}C$ to $2,200^{\circ}C$ for the atomization as well as the sensitivity and reproducibility were improved. The absorbance of bismuth was maximum and not changed in the range of Pd $3-25{\mu}g/mL$. And several materials were examined as an auxiliary modifier. The mixed solution of $1{\mu}g/mL$ palladium and $200{\mu}g/mL$ nickel have raised the temperatures as with $5{\mu}g/mL$ palladium only. The maximum absorbance of bismuth was shown in the nickel concentration range of $100-300{\mu}g/mL$ in $1{\mu}g/mL$ palladium modified system. With such optimum conditions, the trace amount of bismuth in several water samples could be determined by a calibration curve method, and good recoveries were also obtained.

• Journal of the Korean Chemical Society
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• v.40 no.2
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• pp.109-116
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• 1996

A matrix modification was studied for the determination of trace germanium in mineral waters by electrothermal atomic absorption spectrophotometry (ET-AAS). For this, the type and quantity of modifier as well as the use of auxiliary modifier were investigated to realize the efficient modification. Germanium suffers from low sensitivity and poor reproducibility in ET-AAS determination because of the premature loss of germanium via volatile germanium monoxide formation when heated in the presence of carbon. Therefore, the addition of a matrix modifier is necessary to stablize the germanium, thermally and chemically. By the addition of palladium (10 ${\mu}g/mL)$ as a single modifier to the sample containing 500 ng/mL germanium, the charring temperature could be raised from 800 to $1000^{\circ}C$, and its absorbance was also increased, but the atomization temperature was not raised. In this case, the absorbance of germanium was not changed in the range of 10∼70 ${\mu}g/mL$ of palladium added. On the other hand, it was considered that the use of a mixed modifier could modifiy the matrix more effectively than with a single modifier. The best results were obtained by using 1% ammonium hydroxide as an auxiliary modifier together with 10 ${\mu}g/mL$ palladium. The charring temperature could be raised from 800 to $1100^{\circ}C$, without any change of the atomization temperature. With above optimum conditions, the trace amount of germanium in several mineral waters were determined by a calibration curve method, and good recoveries of more than 95% were also obtained in the samples in which a given amount of germanium was spiked. The detection limit of this method was about 6.9 ng/mL.

• Bulletin of the Korean Chemical Society
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• v.21 no.1
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• pp.56-60
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• 2000

The mechanism of a matrix modification for the trace determination of volatile lead and bismuth by an electro-thermal atomic absorption spectrophotometry was studied by a X-ray diffractometry (XRD). For the investigation of structures, the ash products of the elements were produced by using a palladium as a matrix modifier with or without aluminum or nickel as an auxiliary modifier. The same charring conditions as in the analysis of samples were applied together with much concentrated solution of analytical elements and modifiers in a graphite furnace to get a large amount of the product for XRD. The XRD patterns showed PbPd3 for lead and BiPd3 for bismuth. These mean that the reaction procedures through the charring and atomization were changed from $Pb^{2+}$ ${\rightarrow}$ PbO ${\rightarrow}$$Pb^0$ to $Pb^{2+}$ ${\rightarrow}$ PbO ${\rightarrow}PbPd_3$ ${\rightarrow}$ Pb o for lead and from $Bi^{3+}$ ${\rightarrow}$ BiO ${\rightarrow}$ Bi o to $Bi^{3+}$ ${\rightarrow}$ BiO ${\rightarrow}$ $BiPd_3$ ${\rightarrow}$ $Bi^0$ for bismuth by the addition of modifiers. The volatile elements were stabilized by the formation of palladium alloys through a charring process. Charring temperatures were raised about 500 $^{\circ}C$ by the alloying and the atomization was also stabilized for the enhancement of sensitivities.

• Journal of the Korean Chemical Society
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• v.39 no.3
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• pp.204-212
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• 1995

The graphite furnace atomic absorption spectrophotometric determination of trace lead in water samples was studied using matrix modifiers. In order to modify the sample matrix, the type and optimum amount of the modifier were investigated with a given concentration of Pb solution. In fact, if the matrix is not modified, lead has low ashing and atomization temperatures as to give a low absorbance with bad reproducibility because of its volatility. Therefore, optimum modifiers should be used to stabilize the atomization. In this work, the ashing and atomization temperatures were raised from 400 and $1800^{\circ}C$, to 1,000 and $2000^{\circ}C$, by the addition of palladium to 50 ng/mL lead solution as a modifier. The concentration of palladium was 5.0 ${\mu}g/mL$ in the modified solution. Furthermore, if 1.5 ${\mu}g/mL$ of aluminum was mixed with the palladium modifier as an auxiliary modifier, the ashing temperature could be increased $150^{\circ}C$ additionally. With such a treatment, the sensitivity was improved more than 5 times of the solution unmodified and the reproducible results of less than 5% RSD were obtained in the samples of university's waste water and pipe-washing tap water. It could be concluded that this procedure was quantitative in the determination of trace lead from the recoveries of more than 88% obtained in the samples in which a given amount of lead was spiked.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.75-81
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• 2000

A matrix modification was studied for the determination of trace manganese in several seaweeds by electrothermal atomic absorption spectrophotometry(ETAAS). The type and quantity of modifiers were investigated to realize the efficient modification. Palladium was chosen as a single modifier. By the addition of palladium(5$\mu\textrm{g}$/$m\ell$) to 2ng/$m\ell$ manganese solution, the temperatures were raised from 1,00$0^{\circ}C$ to 1,20$0^{\circ}C$ for the charring and from 2,10$0^{\circ}C$ to 2,20$0^{\circ}C$ for the atomization as well as the sensitivity and reproducibility were improved. With such optimum conditions, the trace amount of manganese in several seaweeds(laver, tangle and brown seaweed) could be determined by a calibration curve method, and good recoveries of more than 965 were also obtained in the samples in which a given amount of manganese was spiked. The detection limit of this method was about 0.048ng/$m\ell$.

• Analytical Science and Technology
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• v.12 no.2
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• pp.130-135
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• 1999

A graphite furnace atomic absorption spectrometry (GFAAS) with matrix modification has been used to determine trace amounts of arsenic, lead and selenium in rice flour samples. A mixed solution of palladium and magnesium nitrate was used as a matrix modifier to convert the analyte elements into a phase of higher thermostability and to increase the volatility of concomitants in graphite furnace. Matrix modification effects by the mixed solution were investigated for several elements (As, Cd, Cu, Pb, Se, Zn). It has been found that the matrix modifier substantially increase the pyrolysis and atomization temperature, and absorbance for As, Pb and Se. The concentration of As, Pb and Se in rice flour samples were determined by standard addition method with Zeeman background correction after microwave acid digestion. In this method the characteristic concentrations of As, Pb and Se are 26 ng/g, 18 ng/g, 24 ng/g on the basis of dry sample respectively.