Determination of Co, Cr, Mn and Ni traces in fluorine containing materials for optical fibers using laser enhanced ionization techniques with flame and rod-flame atomizers

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• 作者：Chekalin ; N. V. ; Khalmanov ; A. ; Marunkov ; A. G. ; Vlasov ; I. I. ; Malmsten ; Y. ; Axner ; O. ; Dorofeev ; V. S. ; et. al.
• 刊名：Spectrochimica Acta Part B: Atomic Spectroscopy
• 出版年：1995
• 出版时间：July, 1995
• 年：1995
• 卷：50
• 期：8
• 页码：753-761
• 全文大小：672 K

文摘

Two fluorine-containing materials (NH<sub>4sub>F and NaF) for optical fiber production have been analyzed with respect to their contents of Co, Cr, Mn and Ni using two different laser enhanced ionization (LEI) techniques, one using a rod-flame as an atomization-ionization system and one using a flame as the atomizer. One advantage of the rod-flame system is that it can separate the evaporation and atomization steps which thereby leads to a reduction of the influences of matrices. Another advantage is that it can be used for analysis of both solid and liquid samples. The NH<sub>4sub>F sample was analyzed as a solid and also as a solution (dissolved to 50 or 100 g/l in water). In the flame atomizer the NH<sub>4sub>F matrix created a non-selective ionization background giving detection limits in the order of tens of ng/g (concentrations in the solid sample). Using the rod-flame system, however, it was found that Cr, Mn, and Ni could be determined in the NH<sub>4sub>F sample down to a few ng/g by analysis of the sample solutions without any need for pre-concentration procedures. Direct analysis of solid samples, without any sample preparation, could also be done using the rod-flame system with a ten-fold improvement in detectability. The detection limits for analysis of the solid samples were estimated to be the following: Co, 1 ng/g; Cr, 0.2 ng/g; Mn, 0.3 ng/g; and Ni, 0.08 ng/g. The NaF sample was more complicated to analyze. When using the flame, a significant ionization background was obtained even for solutions diluted down to 0.2 g/l. However, using the rod-flame system, analysis of the elemental content of the NaF sample could be performed. Detection limits in the range of tens of ng/g could be obtained from diluted solutions (≤20 g/l). It was found that the NH<sub>4sub>F and NaF material contained the following concentrations of impurities (HN<sub>4sub>F: Cr, 70 &plusmn; 5 ng/g; Mn, 88 &plusmn; 6 ng/g; and Ni, 56 &plusmn; 5 ng/g. NaF: Cr, 290 &plusmn; 70 ng/g; Mn, 40 &plusmn; 15 ng/g; and Ni 2200 &plusmn; 400 ng/g). For the case of Co, only an upper limit could be assessed (<1 ng/g for NH<sub>4sub>F and <70 ng/g for NaF).