(Received 2 December 2003, Accepted 4 February 2004)

Transcription

1 BUNSEKI KAGAKU Vol. 53, No. 4, pp. 345 _ The Japan Society for Analytical Chemistry 1 R 1 1 Highly sensitive determination of boron with 1,8-dihydroxynaphthalene-3,6-disulfonic acid in ultrapurified water by fluorescence detection/flow-injection analysis Zhen Hai LI 1,Mitsuko OSHIMA 1 and Shoji MOTOMIZU 1 1 Department of Chemistry, Faculty of Science, Okayama University, 3 1 1, Tsushimanaka,Okayama-shi, Okayama (Received 2 December 2003, Accepted 4 February 2004) Boron as boric acid was determined as a complex with chromotropic acid at ph 6.0 in an aqueous medium by fluorescence detection/flow-injection analysis. The complex was detected by measuring the fluorescence intensities (λ ex 313 nm, λ em 360 nm). EDTA was used as a buffer component with the role of a masking agent to metal ions. The background fluorescence of chromotropic acid could be decreased by mixing with 0.1 M ammonia water after complex formation, resulting in a stable baseline. The calibration graph was rectilinear over mol dm 3 (M), and the detection limit was M (S/N 3). The reproducibility was 3.61 (n 10, with the peak height) at M of boron and sample throughput was 40 h 1. Applications to river water, ion-exchanged water and distilled water could be achived without any pretreatments. For the analysis of ultrapurified water, an evaporation/preconcentration procedure was carried out, because the concentration was under the LOD and no reference water which could be used for the carrier solution or preparation of the reagent solutions. Keywords : boron ; chromotropic acid ; ultrapurified water ; fluorescence/flow injection analysis. 1 sub-ppb ppt JIS 1) ICP-AES 2) 4) ICP-MS 5) 8) GFAAS 9) 2,6-10) 2,4- -1,8-11) 4,6-di-tert ) / 1 : HPLC 13)14) ppm sub-ppm FIA 15) 20) 21) 25) ppb ppb sub-ppb FIA/ 16)17)

2 346 BUNSEKI KAGAKU Vol Fig. 1 Flow system for boron determination RS : reagent solution : M chromotropic acid 0.01 M EDTA 0.1 M acetate buffer (ph 6.0); CS : carrier solution : MilliQ water ; AS : ammonia (0.1 M); RC 1 : reaction coil (2 m); RC 2 : reaction coil (1 m); P 1 : pump (0.8 mm/min); P 2 : pump (0.4 mm/min); D : detector ; R : recorder 0.15 g/l 0.5 M ph M ph 6.0 1:1 : Auto Pure, WQ500 Yamato : 0.1 M : g 500 ml M 3 17) : M 17) : M ppt FIA/ Fig. 1 FIA/ PFA-300 FIA ml/min RF-10AXL FBR-252A 0.5 mm PTFE RC 1 2m RC 2 1m 2 2 RS : 0.02 M EDTA 7.4 g/l M 3 1,,,,, Lapid 26) 313 nm 380 nm 313 nm 360 nm 0.5 mm, 1 4 m 2 m ml/min 0.4 ml/min RC µl 200 µl 3 2 ph OH pk a ph OH

3 : /FIA 347 Fig. 2 Effect of reaction ph Boric acid : M Fig. 3 Effect of chromotropic acid concentrations Boric acid : M 17) Na 2CO M 0.1 M 3 3 ph ph ph Fig M EDTA ph 6.2 EDTA EDTA 0.01 M 0.1 M Fig. 2 ph 6.0 ph Fig. 3 Table 1 Conditions adopted for the determination of boron Carrier solution ultrapurified water Reagent solution M chromotropic acid 0.01 M EDTA 0.1 M acetate buffer (ph 6.0) Flow rate P 1, P 2 : 0.4 ml min 1 Sample volume 200 µl Reaction coil RC 1 : 0.5 mm i.d 2 m; RC 2 : 0.5 mm i.d 1 m Wavelength λ ex : 313 nm, λ em : 360 nm Linearity of the M calibration graph M M M 3 5, Fig. 1 Table M S/N 3

4 348 BUNSEKI KAGAKU Vol Fluorescence intensity/a. u. Fig. 4 Flow signals for calibration graphs of boric acid A: 10 9 M level ; B : 10 8 M level ; C : 10 7 M level M Fig M n FIA 100 ml 4 7 ml FIA

5 : /FIA 349 Table 2 Table 3 Table 2 Contamination of boron from vessels Boron found Beaker a) Enrichment No. ratio b) Measured/ In samples/ Average/ 10 9 M M M A A B B C C D D Ultrapurified water, g, was evaporated to about 6 16 ml. a) A : transparent silica beaker ; B : not transparent silica beaker ; C : PTFE beaker ; D : glass beaker. b) Residual water was weighed by a chemical balance, and the enrichment ratio was calculated. FIA 100 Table ( 0.34) M RSD Elix10/MilliQ Element 100 ml 30 FIA Table ( 0.06) 10 9 M 2.45 ICP-MS M Table 3 Boron Residual added/ sample/ 10 9 M g Determination of boron in ultrapurified water by standard addition method Enrichment Boron found ratio Measured/ In samples/ Average/ 10 8 M 10 9 M 10 9 M Recovery, Ultrapurified water taken was g. Sample No. Table 4 Reproducibility of boron measurement with enrichment by vaporization on a hot plate Residual Boron Enrichment sample/ ratio Measured/ Found/ g 10 9 M M Mean

6 350 BUNSEKI KAGAKU Vol Method Table 5 Pretreatment Determination of boron in ultrapurified water Concentration Boron found/ Average/ ratio 10 9 M a) 10 9 M FIA Evaporation/Concentration ICP-MS None 0.99 a) Mean value of triplicate measurements, with the deviation from each mean value Table 6 Determination of boron in waters Sample Pretreatment Boron found/m Asahi River A None B None Deionized A None water B None C None Deionized/ A None Distilled B None water C None Ultrapurified a) A Evaporation/ water Concentration (E/C) B (E/C) C (E/C) a) Used as a carrier 3 8 Table M FIA/ M ICP-MS 1) JIS G 1227, (1999). 2) R. K. Winge, V. A. Fassel, V. J. Peterson, M. A. Floyd : Inductively Coupled Plasma-Atomic Emission Spectroscopy, p. 266 (1985), (Elsevier Sci. Pub., Amsterdam). 3) : (Bunseki Kagaku), 36, 693 (1987). 4),, : (Bunseki Kagaku), 32, T50 (1983). 5) W. Rock, G. Richard : Semiconductor Pure Water and Chemicals Conference, 20th, p. 15 (2001). 6) K. Katsu, K. Yoko : Semiconductor Pure Water and Chemicals Conference, 21st, p. 88 (2002). 7) S. Kozono, S. Takahashi, H. Haraguchi : Analyst, 127, 930 (2002). 8),, t :, ) R. Kobayashi, S. Okamura, K. Yamada, M. Kudo : Anal. Sci., 13, 31 (1997). 10) M. Oshima, K. Fujimoto, S. Motomizu, K. Toei : Anal. Chim. Acta, 134, 73 (1982). 11) K. Toei, S. Motomizu, M. Oshima, H. Watari : Analyst, 106, 776 (1981). 12) M. Oshima, K. Shibata, T. Gyoten, S. Motomizu, K. Toei : Talanta, 35, 351 (1988). 13) Z. Jun, M. Oshima, S. Motomizu : Analyst, 113, 1631 (1988). 14) M. Oshima, S. Motomizu, Z. Jun : Anal. Sci., 6, 627 (1990). 15) F. J. Krug, J. Mortatti, L. C. R. Pessenda, E. A. G. Zagatto, H. B. Filho : Anal. Chim. Acta, 125, 29 (1981). 16),,, : (Bunseki Kagaku), 35, 344 (1986). 17) S. Motomizu, M. Oshima, Z. Jun : Anal. Chim. Acta, 251, 269 (1991). 18) T. Lussier, R. Gilbert, J. Hubert : Anal. Chem., 64, 2201 (1992). 19) S. D. Yurtsever, E. Nusret : Turk. J. Chem., 25, 305 (2001). 20) C. S. Sastri, V. Iyengar, G. Blondiaux, T. Sauvage, Y. Tessier : J. Radioanal. Nucl. Chem., 254, 53 (2002). 21),,,, : (Bunseki Kagaku), 51, 841 (2002). 22) M. Taddia, M. G. Cerroni, E. Morelli, A. Musiani : Annali di Chim., 92, 1045 (2002). 23) D. F. Kuemmel, M. G. Mellon : Anal. Chem., 29, 378 (1957). 24) T. Korenaga, S. Motomizu, K. Toei : Analyst, 103, 745 (1978). 25) S. Motomizu, I. Sawatani, M. Oshima, K. Toei : Anal. Chem., 55, 1629 (1983). 26) J. Lapid, S. Farhi, Y. Koresh : Anal. Lett, 9, 355 (1976).

7 : /FIA 351 / FIA M FIA ph FIA λ ex 313 nm λ em 360 nm 10 9 M S /N M 5 ppt M 10 RSD 3.6 n M