Dynamically modified C 18 silica monolithic column for the rapid determinations of lead, cadmium and mercury ions by reversed-phase high-performance liquid chromatography

• Published in: Journal of chromatography. A
• Main Authors: Thirumalai, M, Kumar, S Naveen, Prabhakaran, D, Sivaraman, N, Maheswari, M Akhila
• Format: Journal Article
• Language: English
• Published: Netherlands 28.09.2018
• Subjects: RP-HPLC; C-Silica; Lead; Monolith column; Cadmium; Mercury
• ISSN: 1873-3778
• DOI: 10.1016/j.chroma.2018.07.044

In this article, a new reversed-phase high-performance liquid chromatography (RP-HPLC) method for the rapid, selective and sequential separation of toxic heavy metal ions namely, Pb , Hg and Cd is reported. For this RP-HPLC method, a C silica monolith column (Chromolith RP-18e, 100 × 4.6 mm) has been surface modified using a laboratory-synthesized amphiphilic organic ligand namely, 1,5-dioctanoyl-1,5-diphenylcarbazide (DODPC), which acts an ion-selective receptor, for the separation of the target analytes. The eluted metal ions were subjected to post-column derivatization reaction with 4-(2-pyridylazo) resorcinol (PAR) prior to their detection using a UV-vis detector (at 520 nm). The post-column reagent (PAR; 4.7 × 10 M; pH 9.0; 1.5 mL/min) was mixed with the column eluate through an ingeniously designed T-connector. An ultra-fast separation of Pb , Cd and Hg ions with a retention time of 1.67, 1.88 and 3.62 min, respectively was achieved, using 0.0526 mmol of DODPC coated C monolithic column along with tartaric acid solution (1.0 × 10 M; pH 4.0; 1.0 mL/min), as the isocratic eluent (mobile phase). The chromatographic parameters such as linearity, accuracy, recovery, limits of detection and quantification were validated to achieve superior analytical results. The influence of various analytical parameters such as nature of mobile phase and its concentration, solution pH, flow rate, post-column reagent and its concentration were studied and optimized. The studies revealed a lower detection limits of 0.075, 0.090 and 0.120 μg/L, and a quantification limits of 0.225, 0.270 and 0.450 μg/L, for Pb , Cd and Hg ions, respectively. A linear signal response in the concentration range of 0.05-50.0 μg/mL, was observed for the target metal ions, with an average r value of 0.9994. The method was selective for the target metal ions, with excellent data reliability and reproducibility that accounts for an average recovery value of 99.76%, with a relative standard deviation of ≤1.83%.