Polypyrrole⁻Methyl Orange Raman pH Sensor

The Alphabet of Nanostructured Polypyrrole

This review is devoted to polypyrrole and its morphology, which governs the electroactivity of the material. The macroscopic properties of the material are strictly relevant to microscopic ordering observed at the local level. During the synthesis, various (nano)morphologies can be produced. The formation of the ordered structure is dictated by the ability of the local forces and effects to induce restraints that help shape the structure. This review covers the aspects of morphology and roughness and their impact on the final properties of the modified electrode activity in selected applications.

Synthesis, physical, chemical, biological, mechanical and electronic studies of polypyrrole (PPy) of versatile scales for electro-mechano, pharmaceutical utilities

The Polypyrrole is properly synthesized with the customary ammonium persulphate as an oxidizing agent. The number of reactions for versatile molar ratios (oxidant: monomer) is addressed and pronounced. Powder X-ray diffraction (XRD) analysis revealed the material amorphous nature by wide peak from 20° to 30°. As the molar ratio is changed, the Fourier Transform Infra Red (FTIR) spectrum shows the substantiation of functional groups and peaks are shifted for each specimen slightly. UV-visible spectral study shows a major peak at 320 nm, for typical π-π* transitions. Scanning Electron Microscopic (SEM) study confirmed the agglomerated polypyrrole sample for the surface morphological periphery. It is enabled for electronic filter influx property with versatile macro scale in microns as 3.7874, Polypyrrole is tried for electronic filters as the influx in microns of different scales. Hardness profile for RISE effectiveness and in the biomedical sector as a better anti-diabetic agent by IC-50 values. The hardness value for Vicker's scale of 100 g is 97.9 kg/mm2.

Water as a probe for pH measurement in individual particles using micro-Raman spectroscopy

Atmospheric aerosol acidity impacts numerous physicochemical processes, but the determination of particle pH remains a significant challenge due to the nonconservative nature of the H⁺ concentration ([H⁺]). Traditional measurements have difficulty in describing the practical state of an aerosol because they comprise chemical components or hypotheses that change the nature of the particles. In this work, we present a direct pH measurement that uses water as a general probe to detect [H⁺] in individual particles by micro-Raman spectroscopy. Containing the vibrational bands of ions and water influenced by ions, the spectra of hydrated ion were decomposed from the solution spectra as standard spectra by multivariate curve resolution analysis. Meanwhile, ratios of hydrated ions were calculated between the Raman spectra and standard spectra to evaluate concentration profiles of each ion. It demonstrated that good quantitative models between the ratio and concentration for all ions including H⁺ can be built with correlation coefficients (R²) higher than 0.95 for the solutions. The method was further applied to individual particle pH measurement. The pH value of sulfate aerosol particles was calculated, and the standard error was 0.09 using pH values calculated from the [HSO₄^-]/[SO₄^2-] as a reference. Furthermore, the applicability of the method was proven by detecting the pH value of chloride particles. Therefore, utilizing water, the most common substance, as the spectroscopic probe to measure [H⁺] without restriction of the ion system, this method has potential to measure the pH value of atmospheric particles with various compounds, although more work needs to be done to improve the sensitivity of the method.

MCR-ALS with sample insertion constraint to enhance the sensitivity of surface-enhanced Raman scattering detection

The multivariate curve resolution-alternative least squares (MCR-ALS) algorithm was modified with sample insertion constraint to deconvolute the overlapping peaks in SERS spectra. The developed method was evaluated by the spectral data simulated using a Gaussian distribution function to generate two independent peaks corresponding to a capping agent and an analyte. The spectra were generated with different overlapping levels and various intensity ratios of the analyte to the capping agent. By using MCR-ALS with the sample insertion constraint, the peak of the capping agent was completely excluded to obtain a calibration model of the analyte with R² > 0.95 under all conditions. Furthermore, our developed method was later applied to a real SERS measurement to quantify carbofuran (analyte) using the azo-coupling reaction with p-ATP (capping agent) on silver nanoparticles as a SERS substrate. A calibration model of derivative carbofuran phenol was generated with R² = 0.99 and LOD = 28.19 ppm. To assess the performance of the calibration model, the model was used to estimate the concentration of carbofuran in an external validation set. It was found that the RMSE of prediction was only 2.109 with a promising R² = 0.97.

Reimagining pH Measurement: Utilizing Raman Spectroscopy for Enhanced Accuracy in Phosphoric Acid Systems

Measurement of pH is an integral component of chemical studies and process control; however, traditional pH probes are difficult to utilize in harsh or complex chemical systems. Optical spectroscopy-based online monitoring offers a powerful and novel route for characterizing system parameters, such as pH, and is well adapted to deployment in harsh environments or chemically complex systems. Specifically, Raman spectroscopy combined with chemometric analysis can provide an improved method of online p[H⁺] measurement. Multivariate curve resolution (MCR) analysis of Raman spectra can be utilized to determine speciation as a function of p[H⁺], and the MCR scores assigned to each species can be used to calculate p[H⁺]. Subsequent chemometric modeling can be used to correlate spectral response to p[H⁺]. This was demonstrated with phosphoric acid, a chemical system known to challenge traditional pH probes. Raman spectra exhibit clear changes with pH due to changing speciation, and chemometric modeling can be successfully utilized to correlate those fingerprints to p[H⁺]. With the use of this approach, p[H⁺] of the phosphoric acid system can be accurately measured without foreknowledge of system conditions such as ionic strength.