Repeatability and reproducibility of retention data and band profiles on six batches of monolithic columns

Chromatographic data were acquired for eight different mixtures, under five different sets of experimental conditions, for a total of 30 neutral, acidic and basic test compounds, on a series of six Chromolith Performance columns from Merck. These columns are made of a C₁₈ chemically bonded silica monolith. Each column belonged to a different production batch, so the data reported here characterize their batch-to-batch reproducibility. The parameters studied in this work were the retention times, the retention and separation factors, the hydrophobic and the steric selectivities, the column efficiencies, and the tailing factors for all 30 compounds.     

Phytochemical screening and chemical variability in volatile oils of aerial parts of Morinda morindoides

Morinda morindoides is an important Liberian traditional medicine for the treatment of malaria, fever, worms etc. The plant was subjected to integrated approaches including phytochemical screening and gas chromatography mass spectrometry (GC–MS) analyses. Phytochemical investigation of the powdered plant revealed the presence of phenolics, tannins, flavonoids, saponins, terpenes, steroidal compounds and volatile oil. Steam distillation followed by GC–MS resulted in the identification of 47 volatiles in its aerial parts: 28 were in common including various bioactive volatiles. Major constituents of leaves were phytol (43.63%), palmitic acid (8.55%) and geranyl linalool (6.95%) and stem were palmitic acid (14.95%), eicosane (9.67%) and phytol (9.31%), and hence, a significant difference in the percentage composition of aerial parts was observed. To study seasonal changes, similarity analysis was carried out by calculating correlation coefficient (r) and vector angle cosine (z) that were more than 0.91 for stem-to-stem and leaf-to-leaf batches indicating considerable consistency.     

Chemical properties investigation of commercial cigarettes by a “pseudo” targeted method using GC‐MS‐selected ions monitoring

A “ppseudo” targeted method using GC‐MS‐selected ions monitoring was applied to investigate the chemical characteristics of commercial cigarettes made in China and foreign countries. To identify the components and define the quantative ions for SIM acquisition, a quality control sample was analyzed using GC‐MS full scan. Acquired data were treated with a homemade software. A peak table with 312 components and their related quantitation ions was achieved for SIM acquisition. Structure elucidation was performed using library searching, retention index, standard compounds, and fitted retention time. The fitted retention time was calculated by a linear correction curve obtained using measured and library retention time to verify compounds. A total of 90 compounds were elucidated. Chemical characteristics of different cigarette brands were investigated. The data acquisition was carried out in SIM mode. The principal component and the hierarchical clustering analyses showed that the Chinese domestic flue‐cured cigarettes were significantly different from the domestic blended, the foreign flue‐cured, and blended cigarettes. Sixty‐seven differential compounds were defined using the nonparametric Mann–Whitney test and the group blending samples comparison. Chinese domestic flue‐cured cigarettes have higher concentration of saccharides and lower concentration of organic acids and amino acids.     

Betalain: a particular class of antioxidant pigment

We have analyzed the stability of betalains in juices prepared from Moroccan yellow cactus pears (Opuntia ficus indica (L.) Mill.) as a function of temperature and pH. The experiments were carried out at temperatures ranging from 80 to 100 degrees C with juices at pH 3.5, 5 and 6.5. The degree of pigment retention decreased when the temperature increased. The degradation constant rates were determined for thermal degradation rates of pseudo-first order. The Arrhenius plot obtained for the degradation of betaxanthin from the yellow fruits was not linear. Regardless of the temperature of treatment, the lowest degradation was obtained for pH 5. When some stabilizers were tested for the protection of pigments, the results showed that ascorbic acid was a better protective agent at pH 3.5, increasing the protection by 40%. The inhibitive action of betalain pigments extracted from cactus pears towards corrosion of stainless steel in phosphoric acid was investigated using electrochemical polarization and electrochemical impedance spectroscopy (EIS) methods. It was found that the presence of natural pigments reduces the corrosion rate of the tested metal, especially on addition of the red pigments (97%). The inhibition efficiency increases as the pigment concentration of extracts increases. It was also found that the pigments tested act as mixed inhibitors. The inhibitive action of the extracts is discussed in term of adsorption and that such adsorption follows a Langmuir adsorption isotherm. The calculated values of the free energy of adsorption indicated that the adsorption process is spontaneous.     

Decomposition of Organic Compounds in Coke Plant Wastewater by Ultrasonic Irradiation and Its Combined Process

The paper deals with the degradation of the organic compounds in the coke plant wastewater by the com-bined process of ultrasonic irradiation and activated sludge. The influence factors of the ultrasonic degrada-tion effect such as air atmosphere, initial concentration, ultrasonic power density and the category and con-sumption of catalyst were investigated. A water quality model was used to explain the degradation of differ-ent kinds of organic compounds in the coke plant wastewater by ultrasonic irradiation. After the wastewater was treated by the combined process of ultrasonic irradiation and activated sludge, the COD degradation effi-ciency was 95.74%, which is 63.49% higher than that by the process of activated sludge alone.     

Supplementary Far-Red and Blue Lights Influence the Biomass and Phytochemical Profiles of Two Lettuce Cultivars in Plant Factory

Three different LED spectra (W: White light; WFR: W + far-red light; WB: W + blue light) with similar photosynthetic photon flux density (PPFD) were designed to explore the effects of supplementary far-red and blue lights on leaf color, biomass and phytochemicals of two cultivars of red-leaf lettuce (“Yanzhi” and “Red Butter”) in an artificial lighting plant factory. Lettuce plants under WB had redder leaf color and significantly higher contents of pigments, such as chlorophyll a, chlorophyll b, chlorophyll (a + b) and anthocyanins. The accumulation of health-promoting compounds, such as vitamin C, vitamin A, total phenolic compounds, total flavonoids and anthocyanins in the two lettuce cultivars were obviously enhanced by WB. Lettuce under WFR showed remarkable increase in fresh weight and dry weight; meanwhile, significant decreases of pigments, total phenolic compounds, total flavonoids and vitamin C were found. Thus, in the plant factory system, the application of WB can improve the coloration and quality of red leaf lettuce while WFR was encouraged for the purpose of elevating the yield of lettuce.     

Qualitative and quantitative analysis of the major bioactive phenolic compounds of Glechoma longituba by LC-coupled with PAD and ESI-MS detection

A sensitive and selective method based on HPLC-PAD and Quadrupole TOF ESI-MS-MS is presented for quality control of Glechoma longituba, the major bioactive phenolic compounds of which could be quantified simultaneously. LC-ESI-MS was applied for nine fully identified compounds and another eight partially identified compounds in the plant by comparing their mass spectral data and retention times with those of selected standards and literature data. For quantitative analysis, the chromatographic conditions and extraction procedure were optimized in order to ensure the exhaustive extraction of the plant material. The calibration curves for determination of the nine compounds showed good linearity over the tested ranges (r2 > 0.999). Measurement of intra-day and inter-day variability was conducted to assess precision of the method, and their RSDs were between 2.22%-2.92% and 1.35%-2.95%. The RSDs of repeatability and stability were between 0.90%-2.53% and 1.73%-2.94%. The recoveries of the nine compounds were between 94.7%-106.5%, with RSD value ranging from 0.56%-2.88%. These validation results demonstrated the suitability of the method for the precise and accurate determination of the main constituents of G. longituba. The method was used for the quality evaluation of twenty batches of G. longituba obtained from different regions of China. The multi-index comprehensive evaluation method for the different kinds of compounds can ensure the efficacy and safety of the traditional Chinese medicine.     

Effect of MnO2 and α-Fe2O3 on organic binders degradation investigated by Raman spectroscopy

Vibrational spectroscopy and GC–MS were used to investigate the effect of MnO₂ and α-Fe₂O₃ on the degradation of methyl linoleate and vegetal and animal fatty. The metal oxides are among the most employed pigments in rock art paintings, whereas the organic compounds were used to mimic organic binders potentially used in such paintings.Both oxides were very effective in the catalytic oxidation of the organic substrates and light had no significant effect, qualitatively or quantitatively, on the final products. In the case of methyl linoleate without metal oxide, the effect of light (visible) was investigated and it was demonstrated that the samples kept in the dark produced relatively less oxidation products, although the main products were the same (hexanal, methyl 9-oxononanoate and methyl octanoate). In the presence of MnO₂ and α-Fe₂O₃ methyl 9-oxononanoate was the main product, followed by hexanal. The spectral patterns of the oxidation products were different for manganese and iron oxide and GC–MS demonstrated that more compounds are formed in the former than with α-Fe₂O₃. Vegetal and animal fatty presented the same behavior that methyl linoleate did.The results here reported indicated that the two pigments considered actively contribute to fat degradation and the presence of inorganic pigments is the main factor to take into account when organic binders degradation in rock art paintings are investigated.     

Tracing of surfactants in the biological wastewater treatment process and the identification of their metabolites by flow injection-mass spectrometry and liquid chromatography-mass spectrometry and -tandem mass spectrometry

Results of aerobic biodegradation of alkyl ethoxylates (AEOs), of nonylphenol polyethoxylates (NPEOs), and of NPEO derivatives (sulfonates and sulfates), as well as anaerobic NPEO biodegradation monitored by flow injection analysis (FIA) or liquid chromatographic separation (LC) in combination with mass (MS) and tandem mass spectrometry (MS-MS) are presented. The application of visual pattern recognition in the FIA-MS mode showed quite different degradation pathways for C13-AEOs, so that aldehyde compounds as metabolites could be confirmed by collision-induced dissociation for the first time. Methyl ethers of AEO compounds were found to be persistent under aerobic conditions, while NPEO degradation resulted in nonylphenol polyether carboxylates. FIA- and LC-MS proved that NPEO derivatives used as anionic surfactants were either non-biodegradable (nonylphenol diethoxy sulfonate) or were primarily degraded (nonylphenol polyethoxy sulfates) into compounds of the same molar masses yet of different retention behaviour. Anaerobic degradation of NPEOs led to the generation of nonylphenols, which was confirmed by GC-MS.     

Biomimetic oxidation of plant protecting agents

The suitability of two in vitro oxidation systems as chemical models for the biological degradation of plant protecting agents has been investigated. As representative herbicides diclofop, fenoxaprop, isoproturon, linuron and monolinuron have been oxidised by two systems, the Fentons' reagent and the ascorbic acid oxidation system (AAOS) and the results compared to those of the known metabolic pathways of these compounds. The herbicides have been oxidised by Fentons' reagent (hydroxy radicals). The main products were isolated by preparative scale HPLC and identified with (1)H-NMR and MS. Some of the products have been identified by comparing their retention times and UV/Vis-spectra to those of standard compounds. Several products known from biological degradation are also found after chemical oxidation, however, notable differences between the two pathways have been observed, for instance in the case of diclofop. Oxidation by the AAOS leads to comparable results. Reaction rates for the oxidation with the AAOS have been studied and compared with data known from degradation studies of the herbicides in soil. Compounds which are slowly degraded in soil are oxidised more slowly in the biomimetic process than those with a fast degradation in soil.     

Thin-layer chromatographic investigation of plant pigments in selected juices and infusions of cosmetological importance and their antioxidant potential

ABSTRACT

Fruit preparations (e.g., fruit juices and nectars) are rich in plant pigments and of great demand by the alimentary and pharmaceutical industry, basically not only due to their health-enhancing properties, but also due to their attractive colors and an overall high esthetic valor. Anthocyanins and anthocyanidins are an interesting group of plant pigments, and in this study, a thin-layer chromatographic detection was carried out of two anthocyanins (cyanin and keracyanin) and two anthocyanidins (pelargonidin and delphinidin) in a selection of the commercial and homemade fruit juices and the infusions prepared of dried plants. Moreover, the same preparations were evaluated for their antioxidant properties by means of two spectrophotometric methods (based on the 2,2′-azino-di-[3-ethylbenzthiazoline] sulfonate (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) tests, respectively) and by the dot-blot test (based on DPPH). Finally, an effort was undertaken to correlate the chromatographically established occurrence of plant pigments in the investigated fruit preparations with their antioxidant properties. However, this correlation was not straightforward, and for at least two reasons. First, the four plant pigments considered are not the only secondary plant metabolites which exert an antioxidant activity. Second, different chemistries stand behind the two spectrophotometric antioxidant activity tests (ABTS vs. DPPH), and the different measuring techniques (spectrophotometry vs. dot blot) are assumed. Nevertheless, it was established that the juices and infusions with the highest detected numbers of plant pigments characterize with the high antioxidant activities also (with blueberries, chokeberries, and hibiscus flower on the top positions). In that way, confirmation of the antioxidant potential of the plant pigments was obtained. Moreover, the presence of certain plant pigments in fruit juices and plant infusions was reported for the first time.     

Nature and origin of black spots found on Miró paintings: a non-invasive study

The degradation mechanism of cadmium pigments in an oil painting by Joan Miró is determined and reproduced. All possible chemical reactions leading to the observed alteration are checked in laboratory conditions. The behaviour of the different materials (support, pigments and binding medium) are determined. The study of the reaction and products is made using optical microscopy, scanning electron microscopy (SEM) with an energy dispersive X-ray detector, Fourier transform infrared spectroscopy and X-ray diffraction.     

Repeatability and reproducibility of retention data and band profiles on reversed-phase liquid chromatography columns. III. Results obtained with Kromasil C18 columns.

The reproducibility of the retention data and the band profiles was investigated with Kromasil C18 columns (silica-based monomeric type reversed-phase packing material). High precision data were obtained and statistically compared among five columns from the same batch (column-to-column reproducibility) and six columns, one from each of six different batches (batch-to-batch reproducibility). These data were acquired under five different sets of chromatographic conditions, for a group of 30 neutral, acidic and basic compounds selected as probes following an experimental protocol previously described. Data characterizing the retention time, the retention factor, the separation factor, the column efficiency and the peak asymmetry for the different probe compounds are reported. Factors describing the silica surface interaction with the selected probe compounds, such as the hydrophobic interaction selectivity, the steric selectivity, and the separation factors of basic compounds at different pH values were also determined. The influence of the underlying silica on these data and correlations between the chromatographic and physico-chemical properties of the different batches are discussed.     

Spectral-luminescent analysis of sugar cane juice

A spectral-luminescent analysis has been made of the low-, medium-, and high-molecular mass fractions of sugar cane juice. The presence of pigments was detected in all the fractions. The medium-molecular-mass fraction was distinguished by the most considerable and most diverse composition of the pigments, a substantial contribution to which was made by the products of the alkaline decomposition of sugars. The amounts of pigments in all the fractions of the juice depended on the age of the plant. A pronounced dependence on the age of the plant was characteristic for the medium-molecular-mass fraction.     

GC/MS and 1H-NMR Analysis of Phytanic Acid Synthesized from Natural trans-Phytol and a Synthetic Phytol Standard

Phytanic acid (3,7,11,15-tetramethylhexadecanoic acid) is a bioactive multi-branched fatty acid mainly synthesized by ruminants from trans-phytol which is found esterified in chlorophyll. Many clinical and biochemical studies were carried out with phytol and phytanic acid, but the stereochemistry of both compounds has not been detailed in either case. In this study, we released trans-phytol from a sample of fresh grass and isolated the natural product from the unsaponifiable matter by means of high-speed counter-current chromatography (HSCCC). The trans-phytol obtained by this measure was used as starting material for the synthesis of phytanic acid. The starting material and the products of this synthesis were compared to the compounds generated in parallel from commercial phytol labeled as “cis-/trans-mixture”. While the phytanic acid produced from trans-phytol from the grass sample was enantiopure on C-7 and C-11, the commercial phytol standard proved to be racemic. These differences could be elaborated by means of the trimethylsilylether of phytol and the methyl esters of phytanic acid. Likewise, ¹H-NMR of phytanic acid methyl ester was suitable to distinguish the natural 3R,7R,11R-/3S,7R,11R-diastereomers from all racemic 3RS,7RS,11RS-phytanic acid by means of the signal dispersion of the multiplets at ~2.1 and ~2.3 ppm. Our results indicate that racemic phytol has been used in different chemical, analytical and biochemical studies. Due to the extraordinary relevance of stereoisomerism, future studies should take advantage of the natural products, i.e. trans-phytol and phytanic acid, with R-configuration on C-7 and C-11. Moreover, the specific composition of the compounds used in studies should be addressed in future studies.     

Role of metals and metal-deactivators in polymer degradation

The interaction between metals or metallic compounds and polymers is inevitable in the practical use of polymeric articles, and the stability of the polymers is often modified by these materials. Furthermore, the effect of the metallic compounds on the degradation of the polymers is extremely complicated, and is influenced by various factors.

This contribution deals with the possible role of metals or metallic compounds in the degradation of polymers, and this is followed by some typical examples of degradation by metallic compounds, mostly commercial pigments and transition metal compounds of stearic acid and acetylacetone, in typical commercial polymers. Recent studies of the inhibition of the copper-catalyzed thermo-oxidative degradation of polyolefins by deactivators, both commercial reagents and novel products, are discussed.     

Evaluation of a method based on liquid chromatography-diode array detector-tandem mass spectrometry for a rapid and comprehensive characterization of the fat-soluble vitamin and carotenoid profile of selected plant foods

The feasibility of using reversed-phase liquid chromatography/diode array/tandem mass spectrometry (LC-DAD-MS/MS) for a rapid and comprehensive profiling of fat soluble vitamins and pigments in some foods of plant origin (maize flour, green and golden kiwi) was evaluated. The instrumental approach was planned for obtaining two main outcomes within the same chromatographic run: (i) the quantitative analysis of ten target analytes, whose standards are commercially available; (ii) the screening of pigments occurring in the selected matrices. The quantitative analysis was performed simultaneously for four carotenoids (lutein, zeaxanthin, β-cryptoxanthin, and β-carotene) and six compounds with fat-soluble activity (α-tocopherol, δ-tocopherol, γ-tocopherol, ergocalciferol, phylloquinone and menaquinone-4), separated on a C30 reversed-phase column and detected by atmospheric pressure chemical ionization (APCI) tandem mass spectrometry, operating in Selected Reaction Monitoring (SRM) mode. Extraction procedure was based on matrix solid-phase dispersion with recoveries of all compounds under study exceeding 78 and 60% from maize flour and kiwi, respectively. The method intra-day precision ranged between 3 and 7%, while the inter-day one was below 12%. The mild isolation conditions precluded artefacts creation, such as cis-isomerization phenomena for carotenoids. During the quantitative LC-SRM determination of the ten target analytes, the identification power of the diode array detector joined to that of the triple quadrupole (QqQ) allowed the tentatively identification of several pigments (chlorophylls and carotenoids), without the aid of standards, on the basis of: (i) the UV-vis spectra recorded in the range of 200-700nm; (ii) the expected retention time; (iii) the two SRM transitions, chosen for the target carotenoids but also common to many of isomeric carotenoids occurring in the selected foods.     

A new furanoid diterpene from Caesalpinia pulcherrima

A new cassane-type diterpene isovouacapenol E (1) was isolated from the leaves of Caesalpinia pulcherrima, together with the known compounds caesaldekarin A (3), spathulenol (4), caryophyllene oxide (5), phytol, and sitosterol. The structure of 1 was elucidated by spectral data interpretation.     

Off-line separation and determination of rare earth elements associated with chloroplast pigments of hyperaccumulator Dicranopteris dichotoma by normal-phase liquid chromatography and ICP–MS

An off-line normal-phase liquid chromatography–ICP–MS method has been used for separation and determination of the rare earth elements (REE) associated with chloroplast pigments of Dicranopteris dichotoma. The stability of REE-bound pigments was tested, and almost no destruction of REE-bound pigments occurred during the so-called normal-phase liquid chromatography. The accumulated free REE ions on the microcrystalline cellulose column were cleaned by elution with 5 mmol L^–1 2-ethylhexyl hydrogen 2-ethylhexylphosphonate (P507), to avoid exchange of these free ions with metals from the pigments. When these precautions were taken, the method was applied to the study of REE-bound pigments in D. dichotoma. ICP–MS results showed REE were present in chlorophylls and lutein, although REE concentrations in carotene and pheophytin were both below procedural blank levels. By careful analysis of the eluate fractions containing chlorophyll a it was found that REE-bound chlorophyll a in D. dichotoma was slightly enriched in the fractions with relatively short retention time. Results indicated that the retention time of REE-bound chlorophyll a might be slightly less than that of magnesium chlorophyll a, and REE-bound chlorophylls might be of relatively low polarity in comparison with magnesium bound chlorophylls. This phenomenon could be explained by the special double-decker sandwich-structure of REE-bound chlorophylls, as was reported by us and other authors. On the basis of these results we preferred to consider that REE can replace magnesium in chlorophyll a of D. dichotoma, and that the role of REE-bound chlorophylls in photosynthesis cannot be neglected. These data might be useful for understanding of both the properties of REE-bound pigments and the effect of REE on plant photosynthesis.     

Removal of pharmaceutical residues in a pilot wastewater treatment plant

Concern is growing over the contamination of the environment with pharmaceutical residues, among which non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most abundant groups. Their widespread appearance in the aquatic environment is because of their high consumption and their incomplete removal during wastewater treatment. Because effective operation of wastewater-treatment plants is important for minimising the release of xenobiotic compounds, for example pharmaceutical products, into the aquatic environment, our study focuses on removal of commonly used NSAIDs (ibuprofen, naproxen, ketoprofen, diclofenac) and clofibric acid in a specially designed small-scale pilot wastewater treatment plant (PWWTP). This study shows that, except for diclofenac, steady-rate removal of NSAIDs over a two-year monitoring period has been achieved. Elimination of the compounds in the PWWTP was ≥87% for ibuprofen, naproxen and ketoprofen but only 49–59% for diclofenac. We also studied clofibric acid. Results after one month of operation revealed 30% elimination with no sign of adaptation by the biomass. Also described are degradation products of diclofenac, which we were able to identify because of the similarity of their mass spectra with those in the NIST library and by comparing the retention times of different compounds. Although the structures of these compounds were confirmed with a high probability (99%), we still need to compare the fragmentation of authentic compounds with degradation products formed under our experimental conditions. Degradation products of ibuprofen, naproxen, ketoprofen, and clofibric acid were found but these must be identified by use of high-resolution mass spectrometry and analysis of authentic compounds.