Complexometric and argentometric titrations using thread-based analytical devices

Purim Jarujamrus; Nutthaporn Malahom; Sodsai Puchum; Rattapol Meelapsom; Maliwan Amatatongchai; Atitaya Siripinyanond; Sanoe Chairam; Chadin Kulsing

doi:10.1016/j.talanta.2018.02.058

Complexometric and argentometric titrations using thread-based analytical devices

Talanta. 2018 Jun 1:183:228-236. doi: 10.1016/j.talanta.2018.02.058. Epub 2018 Feb 17.

Authors

Purim Jarujamrus¹, Nutthaporn Malahom², Sodsai Puchum², Rattapol Meelapsom², Maliwan Amatatongchai², Atitaya Siripinyanond³, Sanoe Chairam², Chadin Kulsing⁴

Affiliations

¹ Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani 34190, Thailand; Nanomaterials Science, Sensors & Catalysis for Problem-Based Projects, Faculty of Science, Ubon Ratchathani University, Warin Chamrap, Ubon Ratchathani 34190, Thailand. Electronic address: purim.j@ubu.ac.th.
² Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani 34190, Thailand; Nanomaterials Science, Sensors & Catalysis for Problem-Based Projects, Faculty of Science, Ubon Ratchathani University, Warin Chamrap, Ubon Ratchathani 34190, Thailand.
³ Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand.
⁴ Chromatography and Separation Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Patumwan, Bangkok 10330, Thailand; Center of Molecular Sensory Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.

PMID: 29567169
DOI: 10.1016/j.talanta.2018.02.058

Abstract

This work describes analytical approaches based on simple complexometric and argentometric titrations leading to the color change of a novel microfluidic thread-based analytical device (µTAD). The device was fabricated from a cotton thread (15 cm) treated with indicator solution, providing an easy-to-use platform for rapid measurement of analyte concentration in aqueous solution. The thread was immobilized onto a support, being a polypropylene sheet or box platform, to facilitate loading of liquid samples. Interaction between the deposited reagents and analytes in the samples then occurred within a few minutes. This resulted in zones of color change with different lengths along the thread depending on the analyte concentration. The interaction zones can be analyzed by human eyes based on comparison of the zone lengths with the printed scales which are correlated with the analyte concentrations. Complexometric titration using µTADs was initially investigated for Mg(II) determination in water and rubber latex samples. These devices consisted of two threads which were pretreated with Eriochrome Black T (EBT) and then treated with ethylenediaminetetraacetic acid (EDTA) in N-cyclohexyl-3-aminopropanesulfonic acid (CAPS) buffer at pH 10. Both threads were tied together with a central knot before being attached to the box platform prior to the analysis. Load of sample solution (6 µL) resulted in the length of red-violet color product on the threads being proportional to the concentration of Mg(II) in waters and rubber latex samples with the working concentration range of 25-1000 mg L^-1. In addition, µTAD with a supporting polypropylene sheet consisting of several threads treated with AgNO₃ and K₂CrO₄ indicators was applied for argentometric titration of chloride ion in water and food seasoning samples. After sample loading (3 µL), the initially red-brown threads turned into white corresponding to formation of AgCl(s) on the threads with a working concentration range of 75-600 mg L^-1. Greater selectivity towards Mg(II) and chloride compared with potential interference ions was also observed. All the developed μTADs were applied for analysis of real samples which showed results being in agreement with those obtained by classical titrations.

Keywords: Argentometric titration; Chloride; Complexometric titration; Magnesium (Mg(II)); Microfluidic thread-based analytical device (µTAD).