Optimisation of a Flow Injection System with a Piezoelectric Quartz Crystal Detector for the Determination of Inorganic Mercury

• Published in: Analytical letters Vol. 32; no. 14; pp. 2715 - 2723
• Main Authors: Teresa, M., Gomes, S. R., Morgado, Elisa V., Oliveira, João A. B. P.
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.01.1999; Taylor & Francis
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; General, instrumentation; Mercury; Piezoelectric crystals; Quartz crystal microbalance; Simplex method; Performance evaluation; Mercury ion; Transition metal Ions; Simplex method; Piezoelectric detector; Chemical sensor; Crystal detector; Optimization; Operating conditions; Flow injection
• ISSN: 0003-2719; 1532-236X
• DOI: 10.1080/00032719908543000

A new method combining flow injection methodology with quartz crystal microbalance (QCM) detection is proposed for inorganic mercury analysis. A modified simplex method is used in order to maximise the observed analytical signals (crystal frequency decrease). Six parameters were optimised: the concentration of the acidic carrier solution, the lengths of the sample loop and mixing coil, and the flow rates of the sample carrier, the reductant stream (SnCl 2 ), and the carrier of the mercury vapour (N 2 ). An increase of 18% in the signal of the centroid of the calibration line was achieved, as well as an increase in the sensitivity from 290 Hz μg − to 313 Hz μg − . Following the proposed procedure, detection limits of 47 μg L − of inorganic mercury were found for sample volumes of 0.5 mL.