Rapid, accurate, and precise concentration measurements of a methanol–water mixture using Raman spectroscopy

Abstract

Here we design, construct, and characterize a compact Raman-spectroscopy-based sensor that measures the concentration of a water-methanol mixture. The sensor measures the concentration with an accuracy of 0.5% and a precision of 0.2% with a 1 second measuring time. With longer measurement times, the precision reaches as low as 0.006%. We characterize the long-term stability of the instrument over an 11-day period of constant measurement, and confirm that systematic drifts are on the level of 0.02%. We describe methods to improve the sensor performance, providing a path towards accurate, precise, and reliable concentration measurements in harsh environments. This sensor should be adaptable to other water-alcohol mixtures, or other small-molecule liquid mixtures.

Tailoring Interfaces for Enhanced Methanol Production from Photoelectrochemical CO2 Reduction

“…36 A peak at 1015 cm −1 appears after 1 h of reaction and product accumulation (pink, lower panel). This peak is assigned to methanol's C−O stretching (Figure S11), 37 confirming the generation of methanol as a product. The 2120 cm −1 CO peak is not detected in this spectrum, likely because loosely bound CO bubbles detach from the electrode.…”

3D Nanocomposite with High Aspect Ratio Based on Polyaniline Decorated with Silver NPs: Synthesis and Application as Electrochemical Glucose Sensor

“…Raman spectra of the methanol and the methanol solution of silver benzoate before laser irradiation are characterized by typical methanol peaks at 3360 cm −1 (stretching mode of OH group), 2943 cm −1 and 2834 cm −1 (stretching mode of C-H), 1454 cm −1 (bending mode of C-H) and 1034 cm −1 (stretching mode of C-O) [ 48 ]. The Raman spectrum of the silver benzoate methanol solution after laser irradiation demonstrates new peaks at 431 cm −1 and 836 cm −1 , (ν s C-C of benzene ring and δ(COO − ) correspondingly); a shoulder at 1391 cm −1 , (ν s (COO − )), peak at 1601cm −1 (ν s C-C in benzene ring) ( Figure 5 , range I) and shoulder at 3067 cm −1 ( Figure 5 , range II).…”

Ultrasensitive and Selective Electrochemical Sensor Based on Yttrium Benzenetricarboxylate Porous Coordination Polymer (Y-BTC) for Detection of Pb2+ from Bio-Analytes

“…39,40 An intensive peak confirmed the DMF in synthesized material at 1474 cm −1, which states CH 3 deformation. 41 Brunauer-Emmett-Teller surface area analysis of Y-BTC.-The surface area, pore size and volume were investigated using adsorption-desorption isotherms, pore size distribution Plots, BET and langmuir surface area Plots, respectively. Figure 4a shows adsorption-desorption isotherms.…”