Development of flow systems incorporating membraneless vaporization units and flow-through contactless conductivity detector for determination of dissolved ammonium and sulfide in canal water

Waleed Alahmad; Thanakorn Pluangklang; Thitirat Mantim; Victor Cerdà; Prapin Wilairat; Nuanlaor Ratanawimarnwong; Duangjai Nacapricha

doi:10.1016/j.talanta.2017.09.037

Development of flow systems incorporating membraneless vaporization units and flow-through contactless conductivity detector for determination of dissolved ammonium and sulfide in canal water

Talanta. 2018 Jan 15:177:34-40. doi: 10.1016/j.talanta.2017.09.037. Epub 2017 Sep 18.

Authors

Waleed Alahmad¹, Thanakorn Pluangklang², Thitirat Mantim³, Victor Cerdà⁴, Prapin Wilairat⁵, Nuanlaor Ratanawimarnwong⁶, Duangjai Nacapricha⁷

Affiliations

¹ Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Thailand; Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
² Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Thailand; Chemistry Program, Faculty of Science and Technology, Nakhon Ratchasima Rajabhat University, Nakhon Ratchasima 30000, Thailand.
³ Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Thailand; Department of Chemistry, Faculty of Science, Srinakharinwirot University, Bangkok 10110, Thailand.
⁴ Department of Chemistry, University of the Balearic Islands, 07122 Palma de Mallorca, Spain.
⁵ Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Thailand; National Doping Control Centre, Mahidol University, Bangkok 10400, Thailand.
⁶ Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Thailand; Department of Chemistry, Faculty of Science, Srinakharinwirot University, Bangkok 10110, Thailand. Electronic address: nuanlaorr@g.swu.ac.th.
⁷ Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Thailand; Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand. Electronic address: dnacapricha@gmail.com.

PMID: 29108580
DOI: 10.1016/j.talanta.2017.09.037

Abstract

Use of membraneless vaporization (MBL-VP) unit with two cone-shaped reservoirs is presented for on-line separation and detection of non-volatile species. A flow system comprising two sets of MBL-VP units with a single in-house capacitively coupled contactless conductivity detector (C4D) was developed for dual determination of ammonium and sulfide ions. Using the continuous-flow section, two zones (280μL) of a sample, either mixed with sodium hydroxide (for ammonium) or hydrochloric acid (for sulfide), are separately delivered into the donor reservoir of the MBL-VP units. The acceptor reservoir contains either 150μL of 15μM HCl solution (for ammonia) or pure water (for hydrogen sulfide), respectively. Vaporization and trapping of the ammonia or hydrogen sulfide gas from the donor reservoir into the liquid acceptor cone occur concurrently in the two separate MBL-VP units. After trapping the gas for 3min, the two 150-μL liquid acceptors are sequentially aspirated through the C4D flow cell for recording the changes in the conductivity. Linear calibrations were obtained for ammonium from 5 to 80µM (Volt = (0.0134 ± 0.0003) [NH₄⁺] - (0.01 ± 0.01), r² = 0.998) and for sulfide from 5 to 200µM (Volt = (0.0335 ± 0.0009) [S^2-] - (0.13 ± 0.09), r² = 0.996). Analysis time for both analytes is only 320s. Our method was applied to analyze canal water samples. The results agree well with membrane gas-diffusion flow injection techniques, using bromothymol blue for ammonium and methylene blue for sulfide. Recoveries ranged from 95% to 104%.

Keywords: Ammonium; Contactless conductivity detector; Membraneless vaporization unit; Sulfide.