Quantification of Lignosulfonates and Humic Components in Mixtures by ATR FTIR Spectroscopy

Abstract

The existing techniques for lignosulfonate (LS) in humate fertilizers lack selectivity to humic substances (HS) as the main component; they involve labor- and time-consuming sample preparation to separate the components at the level of detectable LS concentrations. The procedure based on attenuated total reflectance (ATR) FTIR spectroscopy with simple sample preparation for directly quantifying lignosulfonates in aqueous solutions and lignosulfonates and HS in aqueous solutions of preparations based on HS of coal origin (Sigma Aldrich, Powhumus, and Life Force) was developed. Lignosulfonate quantification is possible by exploiting the bands at 1266, 1192, 1093, and 1042 cm−1 with limits of detection of 0.4–2 g/L. Quantifying LS in a mixture with humates includes centrifugation of prepared solutions to separate interfering silicate impurities. LS quantification in the range of 10–100 g/L against HS (up to a 2-fold excess) with an error of up to 5% is possible based on the spectral absorptions at 1093 and 1042 cm−1. Simultaneous quantification of humate in the mixture with an error of up to 10% is possible by exploiting the bands at 1570 and 1383 cm−1 (carboxylates). The study shows the possibility of determining lignosulfonate against an HS background several times higher than lignosulfonate. The developed technique is applicable for analyzing fertilizers of simple composition and quality control of pure humates used for plant growth. Obtaining the most accurate results needs calibration solutions from the same brands that make up the test mixture.

Comprehensive Study of Physicochemical Properties in Poly‐(Vinylidene Fluoride) Membranes Loaded with OPEFB's Lignin/ Lignosulfonate via Phase Inversion

“…The stretching vibration peak of S=O overlaps with the ether peak in the 1195–1168 cm −1 range and the sulfonate peak is also observed at 622 cm −1 [35] . On the other hand, the stretching vibrations of C=C bonds in an aromatic structure are observed at 1600, 1500, and 1400 cm −1 [35,36] …”

“…[35] On the other hand, the stretching vibrations of C=C bonds in an aromatic structure are observed at 1600, 1500, and 1400 cm À 1 . [35,36] During the membrane's characterization, the functional groups incorporated inside the hybrid membrane were first identified using ATR-FTIR. Figure 2a shows the ATR-FTIR spectra of PVDF membrane, PVDF/lignin (PL2 % and PL4 %), and PVDF/ lignosulfonate (PLs2 % and PLs4 %) membranes.…”

Macromolecular Size and Architecture of Humic Substances Used in the Dyes’ Adsorptive Removal from Water and Soil

“…The spectra of FA (typically containing larger amounts of carboxyl groups) differ from those of HA, which contain more aromatic rings [43]. Quantification of coal-derived humic components from mixtures in aqueous solutions has been carried out via ATR FTIR spectroscopy by exploiting the carboxylate bands at 1570 and 1383 cm −1 [44]. Peak intensities of diffuse reflectance infrared Fourier transform (DRIFT) spectra are not useful to calculate HS concentrations.…”

Humic Substances: Importance for Agriculture, Affinity and Interactions with Soil Amendments and Pollutants

“…A simple, rapid, and reliable method for the "Quantification of Lignosulfonates and Humic Components in Mixtures by ATR FTIR Spectroscopy" [14] was developed by E.A. Karpukhina, D.S.…”