Hydrophile-lipophile balance solid phase extraction of surface water organics: Fluorescent elution preference and overlooked fractions

Yuehao Zhan; Chunya Zeng; Xiaohong Chen; Bingjun Liu; Yanqiu Li; Kyu Hur; Shengkun Dong

doi:10.1016/j.chemosphere.2023.138770

Hydrophile-lipophile balance solid phase extraction of surface water organics: Fluorescent elution preference and overlooked fractions

Chemosphere. 2023 Jul:330:138770. doi: 10.1016/j.chemosphere.2023.138770. Epub 2023 Apr 22.

Authors

Yuehao Zhan¹, Chunya Zeng¹, Xiaohong Chen¹, Bingjun Liu², Yanqiu Li³, Kyu Hur⁴, Shengkun Dong⁵

Affiliations

¹ Guangdong Engineering Technology Research Center of Water Security Regulation and Control for Southern China, School of Civil Engineering, Sun Yat-sen University, Guangzhou, 510275, China.
² Guangdong Engineering Technology Research Center of Water Security Regulation and Control for Southern China, School of Civil Engineering, Sun Yat-sen University, Guangzhou, 510275, China; Southern Laboratory of Ocean Science and Engineering, Zhuhai, 519000, China.
³ Zhuhai Water and Drainage Network Co, Zhuhai, 519000, China.
⁴ 4-2-9 Yushima, Bunkyo Ward, Tokyo, 113-0034, Japan.
⁵ Guangdong Engineering Technology Research Center of Water Security Regulation and Control for Southern China, School of Civil Engineering, Sun Yat-sen University, Guangzhou, 510275, China; Southern Laboratory of Ocean Science and Engineering, Zhuhai, 519000, China. Electronic address: dongshk5@mail.sysu.edu.cn.

PMID: 37094719
DOI: 10.1016/j.chemosphere.2023.138770

Abstract

Fluorescent dissolved organic matter (FDOM) in surface water has broad implications on water quality research and operations. Solid phase extraction (SPE) is the most widely used technique to extract FDOM. However, fluorescent elution preferences by common solvents and content of quantifiable chromophores in waste fraction remain largely unknown, both quantitatively and qualitatively. In this work, the preferential selection of various types of FDOM captured by and lost from SPE as characterized by the fluorescence excitation-emission matrix (EEM) were investigated. Three elution solvents (methanol, acetone, and dichloromethane) were adopted to elute the DOM that was enriched on a typical SPE sorbent. Results revealed that high polarity (methanol) and medium polarity (acetone) solvents eluted the highest variety and quantity of humic acid-like substances (Region V), while the low polarity (dichloromethane) elution solvent was more suitable for eluting tyrosine (Region I) and tryptophan (Region II). Compared to eluting only with methanol, sequential elution and recombination using the three aforementioned solvents demonstrated a significant increase in not only DOC recovery (by 7%), but fluorescence integral values and fluorescence characteristics covering collectively much larger fluorescence regions that more closely resembled raw water. For the first time, the fluorescence EEM of waste after loading the sample revealed a previously overlooked FDOM loss of 20%, caused by ineffective adsorption onto the solid phase resin. Substantial carbonaceous and nitrogenous FDOM were present in this fraction (the fluorescence intensity of aromatic protein in waste exceeds 20% of that in raw water), indicating possible underestimations of FDOM-related research in areas such as disinfection byproduct and toxicity work. The results of this study provide both a qualitative and quantitative characterization of the elution and lost products of SPE in capturing FDOM.

Keywords: Excitation-emission matrix (EEM); Fluorescent dissolved organic matter (FDOM); Solid phase extraction (SPE).

MeSH terms

Acetone*
Coloring Agents
Dissolved Organic Matter
Humic Substances / analysis
Methanol*
Methylene Chloride
Solid Phase Extraction
Solvents
Spectrometry, Fluorescence / methods

Substances

Methanol
Acetone
Methylene Chloride
Dissolved Organic Matter
Coloring Agents
Humic Substances
Solvents