Phenolic Degradation Products Research Articles

Determination of phenolic compounds in alcoholic beverages by HPLC with an electrochemical detector

A method has been developed for the quantitative determination of phenolic lignin degradation products in alcoholic distillates. After diluting the samples with the eluent (1:5-1:10, v/v) the phenolic compounds are separated by high-pressure liquid chromatography and detected by an electrochemical detector at +1.3 V. To identify the compounds the k'-values and the hydrodynamic voltammograms of the samples are compared with those of the standard solution. Several distilled alcoholic beverages were analysed. The content of phenolic compounds was found to vary between 0.15 and 7.7 mg/l. The detection limits were 0.3-0.9 ng.

The need for organic reference materials in marine science

The reference materials (RMs) available for organic trace analysis (OTA) and the development programmes of the RM producers are reviewed. The need for a wider range of determinants, matrices and classes of RMs, particularly the more widespread use of laboratory RMs (LRMs) is discussed. Additional certified RMs should include phenolic surfactant degradation products, chlorophenolics from the wood and paper industries, and organobromines from fire retardants. RMs as molecular markers of geogenic, pyrogenic and biogenic sources; chlorophylls and xanthophylls as a measure of marine productivity and natural shellfish toxins are proposed.

Lignin signature of subalpine Rendzinas (Tangel‐ and Moderrendzina) in the Bavarian Alps

AbstractSimple phenolic lignin degradation products released from alkaline CuO oxidation are used to characterize the lignin component of a Tangelrendzina and a Moderrendzina. The sum of CuO oxidation products describes the overall lignin decomposition pattern. The ratio of acid/aldehyde of the vanillyl unit and the ratio of syringyl/vanillyl units give an indication of the alteration of the remnant lignin molecule.In both soils the sum of lignin oxidation products shows a pronounced decrease with depth. In the Oh, Ca horizon of the Tangelrendzina and the Ah of the Moderrendzina an accumulation of lignin‐derived phenolic compounds is observed. The strong increase of the acid/aldehyde ratio at the transition from the humus to the mineral horizons in both soils and the decrease of the syringyl/vanillyl ratio in the Moderrendzina demonstrate a considerable chemical alteration of the remnant lignin molecule (oxidation of side‐chain, enrichment with vanillyl units) with progressive decomposition and humification of litter material. The depth functions of the lignin parameters are influenced by decomposition of lignin, accumulation of water‐soluble lignin fragments and the input of root litter.

Studies on isolated lignins and lignins in woody materials by pyrolysis-gas chromatography-mass spectrometry and off-line pyrolysis-gas chromatography with flame ionization detection

Wood and milled wood lignins from beech ( Fagus sylvatica L.), spruce ( Picea abies Karst.), bamboo ( Bambus sp.) and teak wood ( Tectona grandis L.f.) were subjected to two types of pyrolysis: (1) direct pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and (2) off-line Py-GC with flame ionization detection (FID). Py-GC-MS studies were used for the identification of phenolic degradation products; 67 substances were identified, 50 of which could be quantified by GC-FID using authentic compounds. It was demonstrated that off-line Py-GC-FID is a suitable method for lignin classification of composed lignocellulosic materials without isolation of lignin. Quantitative pyrolysis results were used to calculate H: G: S ratios of lignins and the results were compared with data obtained from nitrobenzene oxidation and Fourier transform infrared analyses. Results of both of these methods were in good agreement with the off-line Py-GC-FID results.

Characterization of lignin in forest humus layers by high-performance liquid chromatography of cupric oxide oxidation products

A rapid method is described to prepare samples, separate and quantify phenolic lignin degradation products obtained from the alkaline cupric oxide oxidation of forest humus layers. The whole sample is treated with CuO-NaOH at 170°C to produce simple lignin-derived phenols, which are extracted with a commercially-available disposable column system. The extracted phenolic compounds are separated by reverse-phase high-performance liquid chromatography, based on the differential polarity of benzoic acids, aldehydes and cinnamic acids. Results from the oxidation of gymnosperm and angiosperm litter are presented.

Analysis of acidic and phenolic biomass degradation products by isotachophoresis

Two isotachophoretic systems for the determination of biomass degradation products are described, by means of which the separation of 10 acidic and 4 phenolic components has been achieved in the nanomol range. Detection was carried out by conductivity measurement; as regards the phenolic compounds, also the UV absorption at 254 nm was recorded. Apart from reference samples, an alkaline degradation solution was tested in order to point out the scope of application in the analysis of biomass.

The Exhaustive Alkaline Cupric Oxide Oxidation of Humic Acid and Fulvic Acid

AbstractA humic acid and a fulvic acid were subjected to successive oxidations with alkaline cupric oxide at 170C for 3 hours until identifiable degradation products were no longer formed. Resistant humic acid and fulvic acid residues were then oxidized with alkaline permanganate. Following each oxidation, the degradation products were extracted into ethyl acetate, methylated, separated by column, thin‐layer and gas‐chromatography and identified by mass spectrometry and micro‐IR spectro‐photometry.The exhaustive alkaline cupric oxide oxidation of 1.0 g of humic acid yielded 109.0 mg of aliphatic compounds (mainly succinic acid and the n‐C16 and n‐C18 fatty acids), 94.9 mg of phenolic acids and 36.2 mg of benzene‐carboxylic acids. Oxidation of 1.0 g of fulvic acid produced 104.7 mg of aliphatic compounds, 146.7 mg of phenolic acids and 35.1 mg of benzene‐carboxylic acids. The resistant humic and fulvic acid residues yielded on further oxidation with alkaline permanganate additional amounts of benzene‐carboxylic acids.Compared to other degradation methods, alkaline cupric oxide oxidation of humic substances was found to be an efficient procedure for the formation of relatively large amounts of aliphatic and phenolic degradation products but was less effective for degrading aromatic structures linked by C‐C bonds only. The main reaction governing the alkaline cupric oxide oxidation of the humic substances appeared to be alkaline hydrolysis. The data indicate general similarities in the chemical structures of the two humic materials but with the fulvic acid containing more phenolic structures than the humic acid.

Comparative effects of dichlobenil and its phenolic alteration products on photo- and oxidative phosphorylation

Effects of dichlobenil (2,6-dichlorobenzonitrile) and its phenolic degradation products (2,6-dichloro-3-hydroxybenzonitrile and 2,6-dichloro-4-hydroxybenzonitrile) were compared on electron transport and phosphorylation in isolated spinach ( Spinacia oleracea L.) chloroplasts and mung bean ( Phaseolus aureus Roxb.) mitochondria. In chloroplasts, the hydroxylated derivatives inhibited both photoreduction and coupled photophosphorylation with water as the electron donor and with ferricyanide as oxidant, and cyclic photophosphorylation with phenazine methosulfate as the electron mediator under an argon gas phase. In mitochondria, the phenolic derivatives acted as uncouplers of oxidative phosphorylation as evidenced by the stimulation of ADP-limited respiration, circumvention of oligomycin-inhibited non-ADP-limited respiration, and the induction of ATPase activity. Treatment of excised mung bean hypocotyls by the phenolic derivatives also resulted in a very rapid and drastic lowering of ATP levels. In all assays, only limited, if any, interference was expressed by dichlobenil even at relatively high molar concentrations. Inhibition of oxidative and photophosphorylation by the phenolic degradation products, but not by dichlobenil, suggests that if there is a delay between the formation of the hydroxylated compounds and their conjugation, photosynthesis and respiration will be inhibited. Because biochemical and physiological processes depend on oxidative and photophosphorylation for the energy (ATP) needed to drive the reactions, interference with ATP production could be one of the major mechanisms through which phytotoxicity is expressed by the phenolic degradation compounds of the herbicide, if they should accumulate in the free from. Species selectivity may be related to the rate of formation of the phenolic products in different plants and the rapidity of conjugate formation.

Nature of Betanin, the Pigment of Red Beet

THE interesting communication of R. G. Peterson and M. A. Joslyn on this subject calls for some comment. In the first place, the term “nitrogenous anthocyanin” is used partly chemically (nitrogenous) and largely botanically (anthocyanin) to denote an obviously related group of water-soluble bluish-red colouring matters, such as those of Beta, Atriplex, Celosia, and certain Cactaceae. The only evidence favouring some form of amino-flavylium salt structure, which was the basis of a working hypothesis, was the colour and some other properties of synthetic amino-flavylium salts containing hydroxyl and methoxyl groups1. There was a certain resemblance between the absorption spectra in the visible region of betanin and 4′-amino-3 : 7-dihydroxyflavylium chloride. However, no phenolic degradation products could be obtained from betanidin2. We have always recognized that the relation to the flavylium group was unconfirmed and a purely speculative hypothesis. The evidence in favour of a pyrroloid constitution is not much stronger.