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Cacao pod husks (CHs), the most abundant by-product of cacao beans production, can potentially become a source of functional ingredients for the food, cosmetic, and pharmaceutical industries.

Composite cellulose hydrogels result from physical or chemical crosslinking processes. Unique tridimensional architectures, arising from the hydrogel components’ interactions, make these materials ideal to design function-driven structures. We follow the development of cellulose nanofiber/silver nanoparticle (Ag NP) hydrogels in aqueous media. TEMPO-oxidized cellulose nanofibers (TOCNs), extracted from fique residual biomass, acted as both capping and reducing agents for the in-situ synthesis of Ag NPs. Temperature and COONa:AgNO3 molar ratios influence hydrogel formation. Increasing temperatures (60 oC) resulted in shorter reaction times (28 h) compared to the behavior at lower temperatures (25 oC), which required longer reaction times (192 h). High COONa:AgNO3 molar ratios (1:3) produced stiffer and darker TOCN/Ag NP hydrogels at the expense of large cubic Ag NP clusters formation (1 µm). Conversely, lower COONa:AgNO3 molar ratios (1:1) resulted in softer hydrogels with spherical Ag NPs exhibiting diameters between 15 and 80 nm. Ag NP formation and crosslinking processes strongly depend on unreacted aldehydes on the TOCN surfaces after the TEMPO oxidation reaction. IR spectra indicated that there is a bridging bidentate interaction between COO− groups and Ag+ ions. These carboxylate-metal complexes might weaken the hydrogen bond system by increasing the distance between cellulose molecules, decreasing the material’s crystallinity index, as observed in XRD analyses. TGA analyses demonstrated that Ag NPs significantly increased the TOCN/Ag NP hydrogels’ thermal stability compared to TOCN hydrogels. Rheological probing of the hydrogels elucidated the role of Ag NP distribution and loading on the elastic response to cyclical deformations, suggesting a myriad of uses for these materials, particularly in medicinal applications.

Matrices used in Matrix-Assisted Laser Desorption/Ionization (MALDI) Mass Spectrometry (MS) make part of the ionization process and therefore have a big impact in efficient mass-charge spectral generation. We have evaluated 34 novel molecular structures based on Fluorene (SFS-, CN-SFS-, and FLA-), 2,7-Dibromofluorene (FL-), Carbazole and Triphenylamine cores, and (cis-) and (trans-) Bixin as feasible MALDI matrices to analyze labile and thermo unstable molecules. We emphasize that, by default, these molecular cores have viable physicochemical features for MALDI MS assays (UV-vis absorption closed to 355 nm, high solubility, good crystallization capacity, etc), therefore they are optimal candidates for specific and targeted chemical modifications, in order to enhance their physicochemical properties, with the MALDI electron transfer in mind. To characterize and validate the studied chemical species, we have analyzed the Ionization Energy (Ei), from Single Point Energy (SPE) calculations following geometrical optimizations, using computational chemistry at several theory levels. Theory levels ab initio (Hartree-Fock (HF), and Post-HF) and Density Functional Theory (DFT) (B3LYP, PB0, etc) with simple and extended basis sets (STO-3G, cc-pVnZ, def2-SnP; where n = 1, 2, 3, ... , n). Some functional groups such as -OCH3, -OH, and -H lower the Ei in the matrices, while the -CN, NO2 and -COOH functional groups increase their Ei, which is a convenient feature of the matrix-analyte electron transfer process. The next step is to complete the set of relevant physicochemical properties of the selected compounds, such as solubility, quantum yield and crystallization capacity, and to analyze its relationship with the different paths of ionization (electron and proton transfer processes in positive and negative ion mode) in MALDI.

During TEMPO-mediated oxidation of cellulose, primary alcohols on the surface ideally undergo oxidation to carboxylic acids. However, it is well known that some of these hydroxyl groups partially oxidize to aldehydes. To increase the degree of oxidation (DO) of nanocellulose, these unreacted aldehydes can be fully oxidized to carboxylic acids employing various strategies. We performed post-oxidation reactions using NaClO2, on TEMPO-Oxidized Cellulose Nanofibers (TOCN) to investigate how this reaction influenced the physicochemical properties of nanocelulose before and after amidation with octadecylamine (ODA). We report on an increase in the content of carboxylate in TOCN (1.57 mmol/g of cellulose) up 40% after post-oxidation with NaClO2 (2.20 mmol/g of cellulose). These results indicate that with TEMPO-mediated oxidation, 1.57 mmol of hydroxymethyl groups per gram of cellulose were completely oxidized to –COOH, and after treatment with NaClO2, about 0.63 mmol of partially-oxidized alcohols (aldehyde groups) on TOCN were fully oxidized to COOH. Theoretical HLB values of 11.04 and 11.13 for TOCN and post-oxidized TOCN (TOCN-P) indicate that these materials behave as hydrophilic o/w surfactants or emulsifying agents with high affinity for polar phases. They also form highly stable dispersions in water due to an increased charge density as indicated by ζ-potential values of -56 mV for TOCN and -64 mV for TOCN-P. Low contact angles (CA) of 24o and 21o for TOCN and TOCN-P films confirm their hydrophilic nature. After amidation reactions with ODA, we observe a 73% and an 82% decrease in carboxylate content for TOCN and TOCN-P. These values can be related with the degree of coupling (DC) leading to amide formation on the nanocellulose surface, i.e., about 1.14 and 1.80 mmol of amide units were coupled per gram of cellulose on TOCN-ODA and TOCN-P-ODA. ζ-potential values decreased 34% and 52% after amidation, to -37 mV and -31 mV for TOCN-ODA and TOCN-P-ODA, indicating a low stability of these materials in water dispersions. Theoretical HLB values 125o) films illustrate the effect of octadecylamine alkyl chains on the hydrophobic properties of the nanocellulose’s surface. Thermal analysis indicates that amidation reactions can effectively shield in the nanocellulose’s surface from thermal degradation from by increasing the decomposition temperature from around 296 °C for “naked” TOCN to > 330 °C for the “protected” amidated nanocellulose.

Naphthenic acid (NA) fractions from heavy crude oils are typically analyzed in mass spectrometry via electrospray ionization (ESI). Here, we show that NA analysis is also possible by MALDI using a highly basic matrix (proton sponge). When compared with ESI, that allowed detection of six compound families, MALDI resulted in the observation of twenty-two compound families. Besides, MALDI analysis affords compositional-dependent information. Unlike ESI, where all NAs are detected as deprotonated molecules, in MALDI we observe both deprotonated molecules and radical anions. This indicates that ion formation in NA by MALDI can occur by either acid-base and electron-capture mechanisms, or both. Interestingly, the preferred ionization channel seems to be compound class dependent; for instance, the acid base mechanism (which allows detection of deprotonated NA species through a Bronsted-Lowry reaction) applies exclusively to NAs with high H/C ratios along the whole O/C range. On the other hand, for less saturated compounds both mechanisms apply, while the electron capture channel occurs exclusively in species with low H/C and high O/C ratios or high H/C and low O/C ratios (envelope of the van Krevelen plots). In summary, we demonstrate that MALDI(-) is an alternative method for the analysis of complex petrochemical samples offering additional advantages, when compared with ESI, such as increasing compositional space accessibility for polar samples, high throughput and exceptional tolerance to the presence of impurities and salts in the samples. Furthermore, exploration on semi-quantitative approaches in MALDI can provide additional advantages such as those offered by LC-ESI MS, currently used to quantify naphthenic acids.

We present a two-step method to prepare a hydrophobic cellulosic membrane involving a SiO2 sol-gel process, to increase surface roughness, followed by grafting of hexadecyltrimethoxysilane groups to chemically enhance the membrane’s water repellency. The modification processes induced morphological and chemical changes as observed by scanning electron microscopy and infrared spectroscopy, respectively. The hydrophobic membrane was used to separate immiscible oil/water mixtures with efficiencies over 99%. In addition, we tested the material for breaking an asphaltene–stabilized water in oil emulsion and registered separation efficiencies from 75% to 95%. The demulsification process depends on membrane surface hydrophobicity, emulsion viscosity and dispersed droplet size. The hydrophobic/oleophilic cellulose membrane was efficiently reused over 18 times to break a water/oil (50% water) emulsion. This facile solution for breaking low viscosity w/o emulsions and immiscible water/oil mixtures could be easily scalable and used to develop efficient separation methods driven solely by gravity.

Petroporphyrins are biomarkers derived from chlorophyll, bacteriochlorophyll and the heme group, commonly present in crude oils as vanadyl or nickel complexes. These compounds, which despite of the organic matter maturation process preserve the tetrapyrrolic core of their precursors, show low polydispersity, concentration and are commonly used in geochemistry to assess oil lithology, oxidation-reduction conditions, geothermal maturation, conversion of organic matter, and burial depth. The physicochemical characteristics of petroporphyrins make them excellent analytes for MALDI-MS. Electron transfer (ET) ionization in MALDI, using novel electron transfer matrices based on cyano-phenylenevinylenes (e.g. CNPV-CH3), allows direct observation of labile compounds such as polyaromatics and porphyrin-like compounds, chlorophylls and pigments, as has been previously demonstrated by our group. In this work, we analyze petroporphyrins from two South American heavy oils using CNPV-CH3 as ET MALDI matrix. Petroporphyrins were isolated by Soxhlet extraction, with acetonitrile, followed by fractionation using normal-phase column chromatography. UV–Vis measurements showed a strong absorption band at 408 nm assigned to porphyrin Soret band for some chromatographic fractions. The fractions enriched with petroporphyrins were subjected to ET MALDI analysis. We demonstrate the suitability of the CNPV-CH3 MALDI matrix for the efficient and selective desorption and ionization of vanadyl porphyrins, when compared with a commercial MALDI matrix (DCTB) and LDI conditions.

Worldwide only 8% of the biomass from harvested cacao fruits is used, as cacao beans, in chocolate-based products. Cacao mucilage exudate (CME), a nutrient-rich fluid, is usually lost during cacao beans fermentation. CME's composition and availability suggest a potential carbon source for cellulose production. CME and the Hestrin and Schramm medium were used, and compared, as growth media for bacterial cellulose (BC) production with Gluconacetobacter xylinus. CME can be used to produce BC. However, the high sugar content, low pH, and limited nitrogen sources in CME hinder G. xylinus growth affecting cellulose yields. BC production increased from 0.55 ± 0.16 g L−1 up to 13.13 ± 1.09 g L−1 after CME dilution and addition of a nitrogen source. BC production was scaled up from 30 mL to 15 L, using lab-scale experiments conditions, with no significant changes in yields and production rates, suggesting a robust process with industrial possibilities.

Asphaltenes are polydisperse, compositionally complex solubility fractions of crude oil, with a range of structural motifs that contain two primary structural classes: molecules with single aromatic cores (island) and bridged aromatic moieties (archipelago), each with varying degrees of alkyl substitution (e.g., varied-length alkyl units) and multi-heteroatom functionalities responsible for aggregate formation through weak and strong intermolecular associations. Understanding the link between asphaltene molecular composition and problematic behavior, such as deposit and emulsion formation, is vital to improve crude oils up- and downstream processes in petrochemical industries. Some reports suggest that asphaltene precipitation occurs primarily through self-association of polar functional groups and highlight direct correlations between aggregate size and emulsion stability. Here, we compare the molecular composition of whole and thin-layer chromatography (TLC)-fractioned PetroPhase 2017 asphaltenes charac...

As worldwide agricultural production rises, agro-industrial biomass becomes an abundant raw source for uses in energy and materials production. In Colombia fique plants (Furcraea spp.) are traditionally used to extract hard cellulosic fibers using mechanical decortication. Juice, pulp and tow, the by-products of this process, represent almost 95% of the fique leaf weight and are produced in large quantities. Data on these materials is scarce and greatly needed to guide and fuel fique agro-industrial development in Colombia. In this contribution we study the physicochemical properties of fique fibers and by-products (tow and pulp), before and after alkaline hydrogen peroxide treatment (AHP), using spectroscopic and microscopic techniques. Raw/clean fique tow is similar in structure and composition to fique fibers with average cellulose, hemicellulose and lignin contents of 52.3, 23.8 and 23.9%; in this by-product cellulose exists as a highly ordered structure with crystallinity index of 57%. Raw/clean fique pulp, composed of cellulose filaments from secondary cell walls and leaf epidermis, has average cellulose, hemicellulose and lignin contents of 30.5, 29.7 and 9.6%, with cellulose exhibiting an amorphous structure with a crystallinity index of 35%. The AHP treatment of these by-products effectively removed non-cellulosic compounds such as hemicellulose and lignin. After AHP lignin content in fique tow decreases to 2.8% while cellulose crystallinity increases up to 73%, Likewise, fique pulp shows a reduction in lignin to 2.1% and an increase in cellulose crystallinity up to 47%. IR spectroscopic analysis, after AHP, show a decrease of signals attributed to hemicellulose and lignin and FESEM images show a disruption of the lamellar structure in the macro fiber by the removal of hemicellulose, lignin and ground tissue, leaving cellulose fibrils exposed. As the first in-depth report on fique by-products characterization, our results indicate that pulp and tow are interesting lignocellulosic materials due to their significant content of crystalline and amorphous cellulose.

We report on a matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF) method to analyze naphthenic acids (NAs), from petrochemical samples, using 9-aminoacridine (9-AA) and a proton sponge 1,8-bis(dimethylamino) naphthalene (DMAN), as matrices. Singly charged deprotonated molecules of NAs, [M−H] − , dominated the negative ion MALDI mass spectra. The negative ions were pre-formed in solution through an acid/base Bronsted-Lowry reaction promoted by the highly basic matrices (9-AA and DMAN). The DMAN afforded cleaner spectra with absence of clusters, aggregates or matrix interferences at low m / z ; in addition, it provides molecular weight distributions similar to those observed with negative ion electrospray ionization (ESI). In contrast, MALDI spectra obtained with 9-AA exhibits matrix interferences at low mass, and bias towards aliphatic NAs. Finally, we observe the presence of monomeric species in the low mass region and non-covalent aggregates at higher masses in the negative mode MALDI spectra with both matrices, much like with negative mode ESI. We demonstrate that MALDI-TOF/MS is a viable tool for NAs analyses with added advantages such as high throughput and exceptional tolerance to the presence of impurities and salts in the samples, when compared with ESI.

Electron-transfer ionization in matrix-assisted laser desorption/ionization (ET-MALDI) is widely used for the analysis of functional materials that are labile, unstable, and reactive in nature. However, conventional ET matrices (e.g., trans-2-[3-(4- tert-butylphenyl)-2-methyl-2-propenylidene] malononitrile (DCTB)) still lack in performance due to cluster formation, reactivity with analytes, and vacuum instability. In this contribution, we report the use of α-cyanophenylenevinylene derivatives as UV MALDI matrices for the analysis, by ET ionization, of nanoparticles, polymers, porphyrins, and fullerenes. The synthetic versatility of the phenylenevinylene (PV) core allowed us to modulate physicochemical properties, fundamental for efficient formation of primary ions in the gas phase under MALDI conditions, such as planarity, ionization potentials, molar absorptivity, and laser thresholds. For instance, introduction of -CN groups in vinyl positions of the PV core induced structural disruption in planarity in the new α-CNPV derivatives, shifting their maximum molar absorptivity to UV wavelengths and increasing their ionization energy values above 8.0 eV. UV MALDI-relevant photophysical properties in solution and solid state are reported (λ

Cement materials have good compression strength, but poor tensile resistence. Aiming to improve this property, natural fibers can be applied as reinforcement. However, natural fibers have low adhesion with cement, and surface treatments are needed. In this work, sisal fibers were submitted to a cationization process followed by the grafting of two kinds of nanoparticles, Fe2O3 and MnO2. It is a usual treatment to dye fibers to the fabrics. The fibers microstructural characteristics were evaluated, before and after treatment, by using FTIR, XRD, TGA, DSC, SEM, water absorption, and tensile strength tests. The effect of the nanoparticles on the sisal fiber-cement matrix adhesion was evaluated by single fiber pull-out tests. The results show the cationization process removes part of lignin, increasing the fiber crystallinity, while the grafting of nanoparticles reduces the fiber crystalline degree, which indicates that nanoparticles grafting in the lignin spaces. The nanoparticles grafting acts as a catalyst of cellulose formation during the thermal degradation changing the initial fiber degradation profile. All treatments have caused a reduction in the absorbed water amount, become the fibers more stable dimensionally. They have improved the fiber adhesion on the cementitious matrix, being the sisal fiber grafting with MnO2 the best result.

We report a ‘one-pot’ synthetic approach for TEMPO (2,2,6,6-tetramethyl-piperidin-1-oxyl) oxidized cellulose nanofibrils (TOCN) surface amidation by coupling up to 70% of superficial carboxylic units in TOCN with long alkyl chain primary amines (dodecylamine and octadecylamine) using TBTU [O-(1H-benzotriazol-1-yl)-N,N,N’,N’-tetramethyluronium tetrafluoroborate] uronium salt as coupling agent. Raw TOCNs were produced from commercial microcrystalline cellulose and have an elongated highly tangled morphology with nanometric diameters and lengths up to several micrometers with a crystallinity of 62%. TOCN´s degree of oxidation was 1.25 mmol –COOH groups/g cellulose. The TOCN-amidated products named TOCN-AMDC12 and TOCN-AMDC18 depending upon to the primary amine used for the synthesis (dodecylamine –C12– for the former and octadecylamine –C18– for the latter), were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy with attenuated total reflectance and X-ray diffraction. After amidation the hydrated gel-like TOCNs become a cream-colored gel insoluble in water and soluble in toluene. IR data indicates formation of an amide bond after the reaction, and FESEM images suggest a slight increase in fibril width as a result of the long-chain amide derivatives grafted onto the TOCN’s surface. Thermal stability and hydrophobicity of the products were determined using thermogravimetrical analysis and contact angle (CA) measurements. The TOCN-amidated products showed improved thermal properties with maximum decomposition temperatures of 347 and 358 °C, for TOCN-AMDC12 and TOCN-AMDC18 respectively, when compared to the raw TOCN (Td 340 °C); and high hydrophobicity with CA of 61° and 67°, respectively. Finally, the proposed method for TOCN amidation has advantages over current amidation approaches in that it is performed in aqueous media, does not require heating and occurs rapidly (2 h).

Separation strategies coupled with HRMS analysis are vital to increase the scope of the instrumental technique. In this work, we use extrography and column chromatography as fractionation tools for increasing compositional space accessibility in the APPI-FT-ICR mass spectrometric analysis of heavy crude oils. Extrography fractionation was performed on a crude oil sample adsorbed on neutral alumina, using an elutropic series. The crude oil was adsorbed on neutral alumina, and then we applied Soxhlet extraction using acetonitrile, methanol, n-heptane, and toluene, to obtain fractions enriched in metal complexes, polar compounds, maltenes, and asphaltenes, respectively. Considering that polar compounds are responsible for complex operational problems such emulsion and deposit formation, we fractioned the polar extract using normal phase column chromatography to obtain six additional subfractions. All of the extracts were analyzed by APPI FT-ICR mass spectrometry. We detected eleven compound classes in fractions and sub-fractions which were undetectable when analyzing the entire crude oil sample. In terms of the number of molecular formulas, the whole crude oil sample exhibits ∼3700 while ∼11,800 compounds were detected in extrography fractions and column chromatographic sub-fractions. These results indicate that combination of extrography and column chromatography increase compositional space accessibility in around 70%. Specifically, fractionation processes allowed the detection of several compound classes such as NnSs, NnOo, OoSs, NnOoSs (with n = 1; s = 1, 2, 3; o = 1, 2, 3), and N4O1V1, which were undetectable in the analysis of the whole crude oil.

In this contribution, we use high-resolution mass spectrometry to unveil the molecular composition of occluded compounds inside Colombian asphaltenes macrostructures. We use Soxhlet extraction, with n-heptane, coupled with asphaltene maceration to obtain four fractions enriched with chemical compounds occluded inside asphaltene networks. We focused our efforts on the fraction enriched with compounds interacting with asphaltenes via strong intermolecular forces, and used normal phase column chromatography to fractionate it and atmospheric pressure photoionization coupled to Fourier transform ion cyclotron resonance mass spectrometry to obtain a detailed molecular description. Our results indicate that the occluded compounds obtained in the last stage of the washing process are by themselves a complex mixture, consisting mostly of saturated compounds including molecular formulas corresponding to biomarkers, alkyl aromatics with high heteroatom content (up to four heteroatoms), vanadyl porphyrins, and highly...

Formation of water/oil emulsions is a frequent and challenging problem to deal with during crude oil extraction and processing. Crude oil must have water contents (BSW however, alternative surface-active compounds such as biosurfactants are nowadays the topic of active research. In this contribution, we report the use of aqueous suspensions of cellulose nanoparticles, both nanocrystals (CNC) and nanofibrils (CNF), to inhibit the formation of w/o emulsions. HLB values of 13.0 for CNF and 10.7 for CNC indicate that these materials are hydrophilic o/w emulsifying agents, and as such can also act as destabilizers for w/o emulsions. We observe, by recovered water and Near-Infrared (NIR) scattering measurements, that CNC and CNF can effectively function as inhibitors of synthetic w/o and natural w/crude oil emulsions. Aqueous suspensions of CNC and CNF decrease the amount of emulsified water, inhibiting the formation of w/o emulsions up to 75% in some cases.

With heavy crude oil refining on the rise, upgrading strategies are fundamental to yield high-value products. Hydroconversion and thermal cracking are well-established and widely used upgrading processes for heavy oils’ distillation cuts and residues. Recognizing molecular changes in these fractions after upgrading, particularly of asphaltenic compounds, is fundamental to understand and optimize the processes. In this work, we follow compositional changes in the asphaltene fraction of a Colombian heavy crude, after hydroconversion and thermal cracking, using high-resolution mass spectrometry. The liquid products from the upgrading processes were fractionated into maltenes and residual asphaltenes, with yields between 33% and 38% in maltenes from the original asphaltene feedstock. Contoured plots of double bond equivalents versus carbon number and van Krevelen diagrams show maltenic fractions exhibiting lower aromaticity, smaller molecular size, fewer heteroatomic species, and higher content of alkyl side ...

We report on the use of fique natural fibers as solid matrices for the deposition of zinc oxide (ZnO). Fique fibers, native to Colombia, are composed of cellulose (63–70 %) and have a heterogeneous surface morphology with high oxygen density that facilitates metal oxide nanoparticle growth and stabilization. Fique fiber–ZnO biocomposites were synthesized by a co-precipitation method using ZnSO4 as precursor, NaOH for hydroxide formation and thermal/ultrasound energy to promote Zn(OH)2/Zn(OH) 4 2− decomposition and ZnO formation. The biocomposite was characterized using X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy with attenuated total reflectance, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The synthesis of ZnO nanoparticles has been widely reported on inorganic substrates and soft natural fibers; however studies on how experimental parameters affect ZnO features on heterogeneous phase reactions are scarce, as well as the use of hard complex cellulosic fibers as solid supports for its growth. We observed that [OH−]/[Zn2+] ratios, heating or sonication time wield a strong influence on the amount, shape, size and distribution of ZnO crystals on the fique fibers; hence confirming the potential of hard natural fibers as surface active materials for novel biocomposites synthesis. We believe these materials, where the hard fiber robustness and the transition metal oxide catalytic properties are synergistically combined, could be promising functional alternatives that will favor a widespread nanoparticle usage for environmental applications such as wastewater treatment processes.

Asphaltene adsorption properties on mineral surfaces are fundamental to understanding wettability changes in rocks and fluid behavior in reservoirs. In this contribution we report an analytical approach to investigate the molecular features responsible for asphaltene–silica interactions. We used high performance thin layer chromatography silica plates and an elutropic series of solvents to fractionate asphaltenes according to their particular affinity with the mobile and stationary phases. We observed three characteristic asphaltene fractions (with Rfs of 0, 0.69, and 0.90), which were in turn desorbed and analyzed by atmospheric pressure photoionization FT-ICR mass spectrometry (APPI-FT-ICR-MS). In general, polar noneluted compounds highly retained by the silica surface with Rf = 0 exhibit molecular compositions with N1, NnOo and Oo (o = 1, 2, 3 and n = 1, 2) classes and the lowest H/C ratios compared to the other subfractions. Polar CH2Cl2:MeOH-eluted compounds, with Rf = 0.69, have predominantly HC, N...

Phenylenevinylene oligomers (PVs) have outstanding photophysical characteristics for applications in the growing field of organic electronics. Yet, PVs are also versatile molecules, the optical and physicochemical properties of which can be tuned by manipulation of their structure. We report the synthesis, photophysical, and MS characterization of eight PV derivatives with potential value as electron transfer (ET) matrices for UV-MALDI. UV-vis analysis show the presence of strong characteristic absorption bands in the UV region and molar absorptivities at 355 nm similar or higher than those of traditional proton (CHCA) and ET (DCTB) MALDI matrices. Most of the PVs exhibit non-radiative quantum yields (φ) above 0.5, indicating favorable thermal decay. Ionization potential values (IP) for PVs, calculated by the Electron Propagator Theory (EPT), range from 6.88 to 7.96 eV, making these oligomers good candidates as matrices for ET ionization. LDI analysis of PVs shows only the presence of radical cations (M+.) in positive ion mode and absence of clusters, adducts, or protonated species; in addition, M+. threshold energies for PVs are lower than for DCTB. We also tested the performance of four selected PVs as ET MALDI matrices for analytes ranging from porphyrins and phthalocyanines to polyaromatic compounds. Two of the four PVs show S/N enhancement of 1961% to 304% in comparison to LDI, and laser energy thresholds from 0.17 μJ to 0.47 μJ compared to 0.58 μJ for DCTB. The use of PV matrices also results in lower LODs (low fmol range) whereas LDI LODs range from pmol to nmol.

Gold nanoparticles were synthesized on the surface of natural fique fibers extracted from the leaves of Furcraea spp., a plant native to the Andean mountains in Colombia. Fique fibers have a low density, are biodegradable, flexible, highly resistant to wear and exhibit excellent thermal degradation making them promising materials for the textile and packing industries as well as fillers for fiber-reinforced composites. Fique fiber surface was rendered positive using a cationizing agent 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHTAC) under strong alkaline conditions. Cationic fique fibers were impregnated with an anionic gold complex that was further reduced to generate gold nanoparticles onto the fibers surface. The influence of CHTAC reaction times and NaOH:CHTAC molar ratios were examined. It was found that increasing the NaOH:CHTAC molar ratio had a negligible effect on nanoparticle size, while the surface coverage density was positively influenced. We hypothesize that the number of positive charges on the fiber surface is the key factor behind this observation. UV–Vis diffuse reflectance spectroscopy; mechanical tests and field emission scanning electron microscopy were used to characterize the modified fibers and the resulting nanoparticles. The proposed method opens a new path for the development of functional natural renewable substrates.

The dependence of the limonene content of lemon (Citrus volkameriana) peel oil on the degree of ripeness of the fruit has been studied by using steam distillation and cold pressing to extract the oils from lemon fruit peel at different stages of maturation (green, greenish-yellow, and yellow-orange peel coloration). Samples of essential oils were analyzed by high resolution GC and GC-MS, using tetradecane as internal standard for quantitation. Forty components were detected; thirty eight were positively identified by comparison of their mass spectra (El, 70 eV) and Kovats retention indexes (determined using a non-logarithmic scale on capillary columns coated with both polar (DB-Wax) and non-polar (DB-1) stationary phases) with those of standards and with data reported in the literature. The limonene concentration reached a maximum level of 79.4% when the fruit was in the intermediate maturation stage characterized by greenish-yellow coloration.

We report on the in situ synthesis of nanostructured MnO2 onto natural fique fibers. The fiber surface was rendered positive by exposure to alkaline conditions, and permanganate anions (MnO4−) were embedded onto the resultant alkali cellulose via coulombic interactions. An ultrasound-assisted procedure was used to reduce MnO4− and yield MnO2 nanoparticles (NPs). UV-Vis diffuse reflectance was used to assess the influence of the precursor concentration, loading and reduction times on the synthesis of the nanostructured MnO2. FESEM provided direct evidence that MnO2 NPs and aggregates could be formed on the fiber's surface. The catalytic activity of the new bionanocomposite was tested for the removal of indigo carmine dye in water samples. The MnO2–fique fiber bionanocomposite was able to remove up to 98% of the colour present in the contaminated water samples in less than 5 minutes. Mass spectrometry was used to determine the degradation route of the dye. Additionally, we found that the bionanocomposite can be reused with no effect on the dye degradation efficiency. The reported procedure provides a new route for the development of biodegradable and easy to synthesize composite materials capable of efficiently degrading pollutants found in industrial effluents.