title: Fast and precise method for HPLC-size exclusion chromatography with UV and TOC (NDIR) detection: importance of multiple detectors to evaluate the characteristics of dissolved organic matter.
abstract: A new type of high-performance liquid chromatography (HPLC)-size exclusion chromatography (SEC) system with ultraviolet (UV) absorbance detection and non-dispersive infrared (NDIR) detection of total organic carbon is described. The introduction of an online degassing tube and a low-volume HPLC column helped to reduce the analytical time and increase the sensitivity of the SEC system. This study is the first in which linear calibration curves (R(2)>0.99) were obtained for both UV absorbance and NDIR data for polystyrene sulfonate standards, which are the most suitable standards for molecular size analysis of aquatic humic substances as well as dissolved organic matter (DOM). Using the calibration curves, the molecular size distribution of DOM in water collected from Lake Kasumigaura and in pore water from lake sediments was estimated. Most of the DOM had a molecular weight less than 4000 Daltons (Da), and the amount of low-molecular-weight DOM (∼ 2000 Da) with low UV absorbance increased with depth in the sediment pore water. This result shows the importance of combining quantitative analysis by NDIR detection with qualitative analysis by UV detection to determine the chemical and physical properties of DOM. The possible sources and reactivity of DOM in Lake Kasumigaura and its sediment pore water are also discussed.
authors.affiliation: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. kawasaki.nobuyuki@nies.go.jp
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kawasaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Matsushige
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Komatsu
authors.forename: Ayato
authors.initials: A
authors.lastname: Kohzu
authors.forename: Fumiko Watanabe
authors.initials: FW
authors.lastname: Nara
authors.forename: Fumikazu
authors.initials: F
authors.lastname: Ogishi
authors.forename: Masahito
authors.initials: M
authors.lastname: Yahata
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Mikami
authors.forename: Takeshi
authors.initials: T
authors.lastname: Goto
authors.forename: Akio
authors.initials: A
authors.lastname: Imai
mesh_terms: D002138:Calibration; D002244:Carbon / Q000032:analysis*; D002850:Chromatography, Gel / Q000295:instrumentation* / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation* / Q000379:methods*; D005843:Geography; D019015:Geologic Sediments / Q000737:chemistry; D005947:Glucose / Q000032:analysis; D018698:Glutamic Acid / Q000032:analysis; D007564:Japan; D060106:Lakes / Q000737:chemistry; D008970:Molecular Weight; D009930:Organic Chemicals / Q000032:analysis*; D010795:Phthalic Acids / Q000032:analysis; D016062:Porosity / Q000528:radiation effects; D012015:Reference Standards; D012995:Solubility / Q000528:radiation effects; D013890:Thiourea / Q000032:analysis; D014466:Ultraviolet Rays
chemical_list: D009930:Organic Chemicals; D010795:Phthalic Acids; D018698:Glutamic Acid; C032279:phthalic acid; D002244:Carbon; D013890:Thiourea; D005947:Glucose