Investigation of Different Polymers as Coating Materials for IR/ATR Spectroscopic Trace Analysis of Chlorinated Hydrocarbons in Water

Abstract

Polymer-coated attenuated total reflection (ATR) elements have been used to compare the diffusion behavior and enrichment from aqueous solutions of three different chlorinated hydrocarbons (CHCs) — monochlorobenzene (MCB), chloroform (CF), and tetrachloroethylene (TeCE)—into different polymers. The influence of polymer properties such as glass transition temperature and crystallinity and the effect of the polymer background IR absorption and varying thicknesses of the polymer membranes to the detectability were investigated. The crystallinity and the glass transition temperature have a very pronounced influence on the velocity of the diffusion process, whereas the partition coefficient influences the amount of CHC diffusing into the polymer membrane. The time constants for 90% saturation of the polymer with the test analytes are in the range of 8 to 40 min, depending on the nature of the polymer and analyte. A linear calibration graph was obtained for simultaneous detection of all three test analytes in the range from 5 mg/L to 100 mg/L CHC with detection limits of 1.5 to 2 mg/L. Coefficients for CHC partitioning between water and polymers measured by ATR/IR were in good agreement with values determined by GC/MS.

Development of a Solid-Phase Microextraction/Reflection-Absorption Infrared Spectroscopic Method for the Detection of Chlorinated Aromatic Amines in Aqueous Solutions

“…To increase the sensitivity, the principle of solid-phase micro-extraction [7][8][9][10] was applied to the ATR-IR sensing method. [11][12][13][14][15][16][17][18] The sensitivity of the SPME/ATR-IR method was largely enhanced because SPME films exclude water molecules from the evanescent wave and attract organic species into a region near the sensing crystal to enhance the signal. Although this type of method provides a direct way to detect organic compounds in aqueous solution, a tedious optical arrangement and an expansive ATR crystal are required.…”

Sensores ópticos com detecção no infravermelho próximo e médio

“…Gobel e colaboradores 58 estudaram a difusão de três hidrocarbonetos clorados (monoclorobenzeno, clorofórmio e tetracloroetileno) em oito diferentes polímeros (polietileno de baixa densidade, copolímero etileno-propileno, 1,2-polibutadieno, poli-isobutileno, polietileno oxidado, polietileno clorado, copolímero etileno-vinilacetato e poli(4-metil-1-penteno), utilizando medidas de reflexão total atenuada (ATR) com um cristal de ZnSe recoberto pelo polímero (22 ± 2 µm). Os resultados indicaram que para se obter 90% de saturação da fase sensora era necessário um tempo de 8 a 40 min, dependendo da natureza do polímero.…”

Development of an Infrared Hollow Waveguide Sampler for the Detection of Organic Compounds in Aqueous Solutions with Limited Sample Volumes

“…Because of the strong absorption of water molecules in aqueous solutions, the attenuated total reflection (ATR) 1 effect has been used most frequently because of the short traveling distance of the evanescent wave limits absorption by the water molecules. Based on this effect, both un-coated [2][3][4][5][6] and hydrophobic film coated [7][8][9][10][11][12][13][14][15][16][17] internal reflection elements (IREs) have been used to detect organic compounds in aqueous solutions. The sensitivity was greatly improved for methods using hydrophobic film-coated IRE.…”