| Autor: |
Daniel B. Gazda, Marc D. Porter, James S. Fritz |
| Rok vydání: |
2004 |
| Předmět: |
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| Zdroj: |
Analytica Chimica Acta. 508:53-59 |
| ISSN: |
0003-2670 |
| DOI: |
10.1016/j.aca.2003.11.044 |
| Popis: |
Colorimetric solid phase extraction (C-SPE) is an analytical technique in which analytes in water samples are extracted onto a solid adsorbent matrix impregnated with a colorimetric reagent and then quantified directly on the adsorbent surface using diffuse reflectance spectroscopy. This paper presents a further development in C-SPE. In this case, the reagent employed to detect the analyte is not impregnated on the extraction medium. Instead, the reagent is weakly immobilized on a solid support (i.e., filter paper) and released into the sample as it flows through the support. The reagent complexes the analyte in solution, forming a highly colored precipitate that is collected on the surface of an extraction membrane. The concentration of analyte is determined using the Kubelka–Munk function calculated from the diffuse reflectance spectrum of the precipitate on the membrane surface. This precipitation–spectrophotometric platform is extensively evaluated by determining nickel(II) using dimethylglyoxime (DMG) as the precipitating reagent. The ability to optimize reaction conditions with immobilized reagents by in-line buffering is also demonstrated. Specifically, borax buffer was utilized to adjust the pH of nickel(II) samples prepared in deionized water. This combination of immobilized buffer and reagent allows C-SPE to operate in a solid-phase mode in which all the reagents requisite for optimal analyte determination are immobilized on solid supports. Using this method, nickel(II) was determined in a single processing step over the concentration range 0.50–5.0 ppm in ∼40 s with 1.0 ml sample volumes. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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