Preparation of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol nanoparticle-coated test strip and its application to detection of trace cadmium(II) by immersion test

Yukiko Takahashi, Satoshi Souma, Yoshito Wakui

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) nanoparticle-coated membranes were prepared by simple filtration of an aqueous dispersion of 5-Br-PADAP nanoparticles through a cellulose ester membrane filter (0.45 μm pore). By letting the dispersion stand for 3 min at room temperature for sufficient particle growth, more than 99.92 of the 5-Br-PADAP nanoparticles were coated uniformly and firmly on the membrane filter without any additives. A 5-Br-PADAP thin layer was located within 1 μm from the top surface of the filter. The membranes were cut into 6 pieces, and then test strips were immersed in 20 mL of a sample solution containing CdII and pH buffer (immersion test). The test strip changed color from yellow to reddish-orange based on complex formation with CdII. Stirring increased the reaction rate; the color formation at 100 ppb was completed in ca. 30 min under stirring in contrast to more than 90 min without stirring. A very low extraction percentage (0.77 %) of 700 ppb CdII to the 5-Br-PADAP thin layer was obtained by ICP-MS analysis. A detection curve was obtained using ΔE *(a *,b *) of a colorimeter. The equation is expressed as ΔE *(a *,b *) = 73.677 (1 - e-0.0036283 C) and the 3σ detection limit is 7.14 ppb based on 7 blank measurements. To improve the reaction rate and extraction percentage of an immersion test, a drop test was attempted by dropping 50 μL of a sample solution on the test strips equipped with No.1 filter paper as a water absorber. The extraction percentage by the drop test of 1 ppm CdII was 30.2 % for c a. 15 min.

Original languageEnglish
Pages (from-to)229-234
Number of pages6
JournalBUNSEKI KAGAKU
Volume61
Issue number3
DOIs
Publication statusPublished - 2012 Jan 1
Externally publishedYes

Keywords

  • 5-Br-PADAP
  • Immersion test
  • Nanoparticle
  • Thin layer

ASJC Scopus subject areas

  • Analytical Chemistry

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