title: Nonlinear absorbance amplification using a diffuse reflectance cell: total organic carbon monitoring at 214 nm.
abstract: We present an absorption spectrometric method using a polytetrafluoroethylene (PTFE) cell as a diffuse reflector. The system was used for monitoring ultrapure water. All compounds absorb to some degree at low UV wavelengths, and the absorption at 214 nm from a zinc lamp source was monitored using a charge-coupled device (CCD) spectrometer. The absorption was interpreted in terms of total organic carbon present. The cell acts as a nonlinear absorbance amplifier, improving both the limit of detection (LOD) and the dynamic range. Potassium hydrogen phthalate (KHP) and glucose were used to evaluate the system and provided respective LODs of 46.5 ng/L and 4.5 mg/L as carbon. Although the physical path length was 25 cm, a maximum effective path length of 280 cm was observed at the lowest tested KHP concentrations. The system is intended for real-time monitoring of ultrapure water.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Arlington , Arlington, Texas 76019-0065, United States.
authors.forename: Yin-Huan
authors.initials: YH
authors.lastname: Li
authors.forename: C Phillip
authors.initials: CP
authors.lastname: Shelor
authors.forename: Purnendu K
authors.initials: PK
authors.lastname: Dasgupta
mesh_terms: D002244:Carbon / Q000032:analysis*; D005947:Glucose / Q000032:analysis* / Q000737:chemistry; D010084:Oxidation-Reduction; D010795:Phthalic Acids / Q000032:analysis* / Q000737:chemistry; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000032:analysis*
chemical_list: D010795:Phthalic Acids; D014867:Water; C032279:phthalic acid; D002244:Carbon; D011138:Polytetrafluoroethylene; D005947:Glucose