Calibration of NIRS for the Estimation of Fatty Acids in Brassica Juncea

This study was done to test whether near infrared reflectance spectroscopy (NIRS) could be used as a quick substitute for measuring quality characteristics, i.e., a fatty acid profile over gas liquid chromatography. Near infrared reflectance spectroscopy is a multi‐trait technique. In the present study, the fatty acid profiles of seeds of 200 genotypes of Brassica juncea were analysed by gas liquid chromatography. Near infrared reflectance spectra of intact seeds of the same samples were collected (400–2500 nm) on a NIR systems Model 6500 spectrophotometer. The spectra were subjected to scanning, mathematical processing, and statistical analysis using Win ISI software. Data were scored to remove redundancy. Spectra were treated as outliers with H > 3.0 (global H) and similar samples with H < 0.6 (neighbourhood H). Cross validation of the spectra was done using a modified partial least‐square method to develop the calibration equation. The calibration equation had good R² values for oleic acid (R² = 0.91), linoleic acid (R² = 0.83), and erucic acid (R² = 0.88). The internal validation was done to test the goodness of fit of the developed equation. The equation provided reliable estimations of these traits in internal validation with R² values of 0.77, 0.68, 0.81 for the above quoted fatty acids, respectively. The external validation results also showed higher R² values for oleic acid (0.89), linoleic acid (0.69), and erucic acid (0.90). The equation was less reliable for linolenic acid, which had R² values of 0.53 in cross validation, 0.25 for internal validation, and 0.20 for external validation. The results indicated that NIRS could be used to rapidly determine oleic acid, linoleic acid, and erucic acid in intact B. juncea seeds.     

Synthesis and characterization of poly(o‐toluidine) doped with organic sulfonic acid by solid‐state polymerization

Poly (o‐toluidine) (POT) salts doped with organic sulfonic acids (β‐naphthalene sulfonic acid, camphor sulfonic acid, and p‐toluene sulfonic acid) were directly synthesized by using a new solid‐state polymerization method. The FTIR spectra, ultraviolet visibility (UV–vis) absorption spectra, and X‐ray diffraction patterns were used to characterize the molecular structures of the POT salts. Voltammetric study was done to investigate the electrochemical behaviors of all these POT salts. The FTIR and UV–vis absorption spectra revealed that the POT salts were composed of mixed oxidation state phases. All POT salts contained the conducting emeraldine salt (half‐oxidized and protonated form) phase; the pernigraniline (fully oxidized form) phase is predominant in POT doped with β‐naphthalene sulfonic acid, and POT doped with p‐toluene sulfonic acid had the highest doping level. The X‐ray diffraction patterns showed that the obtained POT doped with organic sulfonic acids were lower at crystallinity. The conductivity of the POT salts were found to be of the order 10^?3‐10^?4 S/cm. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1630–1634, 2005     

New fluorescence active cellulosics prepared by a convenient acylation reaction

Novel, fluorescence active cellulosic polymers with high degree of functionalization of up to 1.0 were synthesized in homogeneous phase (cellulose in N,N-dimethylacetamide/LiCl and 6-O-thexyldimethylsilylcellulose in pyridine) with a mixed anthracene-9-carboxylic/p-toluenesulfonic acid anhydride. This novel and effective synthetic method yield the pure carboxylic acid esters of the polymers, which were characterized by means of FTIR- as well as ¹H and ¹³C NMR-spectroscopy. The polymers show typical fluorescence spectra, which are identical with the non-bond anthracene-9-carboxylic acid. Received: 26 August 1997/Accepted: 8 September 1997     

Characterization of primary fatty amides produced by lipase-catalyzed amidation of hydroxylated fatty acids

A novel hydroxylated primary fatty amide was produced from lesquerolic acid by direct amidation with ammonia catalyzed by immobilized Pseudozyma (Candida) antarctica lipase B (Novozym 435) in organic solvent. The amides of ricinoleic acid and oleic acid were also produced for comparison. The hydroxy FA were transformed at comparable rates to that of oleic acid. The rate of amide formation was greater for the longerchain lesquerolic acid than for ricinoleic acid. All products exhibited characteristic primary-amide mass spectrum peaks with a base peak at m/z 59 and a strong ion fragment at m/z 72. Other peaks present are consistent with cleavage on either side of the hydroxyl position. The mass spectra, together with ¹H and ¹³C NMR data, suggest that the products of lipase-catalyzed direct amidation of ricinoleic acid and lesquerolic acid are 12-hydroxy-9(Z)-octadecenamide and 14-hydroxy-11(Z)-eicosenamide, respectively.     

Assignment of13C nuclear magnetic resonance signals in fatty compounds with allylic hydroxy groups

¹³C Nuclear magnetic resonance (NMR) signals in several fatty compounds with allylic mono- and dihydroxy groups were assigned by comparing compounds with and without other functional groups (allylic hydroxy, carboxylic acid, respectively, methyl ester at C₁). The simple¹³C NMR spectra of hydroxylated compounds derived from symmetrical alkenes are particularly useful in making assignments. The compounds whose signals were partially assigned are 8-hydroxy-9(E)-octadecenoic acid, 11-hydroxy-9(E)-octadecenoic acid, 8, 11-dihydroxy-9(E)-octadecenoic acid, 9(E)-octadecen-8-ol, and 9(E)-octadecene-8, 11-diol. The present evaluation can be used for assigning signals in other fatty compounds.     

Photochemical production of conjugated linoleic acid from soybean oil

Conjugated linoleic acid (CLA), an anticarcinogenic compound with numerous other health benefits, is present mainly in dairy and beef lipids. The main CLA isomer present in dairy and beef lipids is cis 9, trans 11 CLA at a 0.5% concentration. The typical minimum human dietary intake of CLA is 10 times less than the 3 g/d suggested requirement that has been extrapolated from animal and cell-line studies. The objectives of this study were to produce CLA isomers from soybean oil by photoisomerization of soybean oil linoleic acid and to study the oxidation status of the oil. Refined, bleached, and deodorized soybean oil with added iodine concentrations of 0, 0.1, 0.25, and 0.5% was exposed to a 100-W mercury lamp for 0 to 120 h. An SP-2560 fused-silica capillary GC column with FID was used to analyze the esterified CLA isomers in the photoisomerized oil. The CLA content of the individual isomers was optimized by response surface methodology. Attenuated total reflectance (ATR)-FTIR spectra in the 3400 to 3600 cm⁻¹ range and ¹H NMR spectra in the 8 to 12 ppm range of the photoisomerized soybean oil were obtained to follow hydroperoxide formation. The largest amount of cis 9, trans 11 CLA isomer in soybean oil was 0.6%, obtained with 0.25% iodine and 84 h of photoisomerization. Lipid hydroperoxide peaks in the ATR-FTIR spectra and aldehyde peaks in the ¹H NMR spectra were not observed in the photoisomerized soybean oil, and the spectra were similar to that of fresh soybean oil. This study shows that CLA isomers can be produced simply and inexpensively from soybean oil by photoisomerization.     

Structural changes of sinapic acid during alkali-induced air oxidation and the development of colored substances

Structural changes of sinapic acid were induced by air oxidation in aqueous solutions at pH 7–10 and followed by spectral and high-performance liquid chromatographic (HPLC) analysis. Color properties of the sinapic acid solutions were determined by taking the transmittance spectra, calculating the Commission Internationale de l’Eclairage (CIE) 1931 tristimulus values, and converting to Hunter L a b values. Reaction rate constants for sinapic acid were determined by a kinetic study based on the quantitative results from HPLC analysis. These reactions were first order with respect to sinapic acid and fit the appropriate equation with a coefficient of R ² >0.97. Sinapic acid was converted to thomasidioic acid with reaction rate constants (k) of 8.54×10⁻⁶, 2.51×10⁻⁵, and 4.87×10⁻⁵ s⁻¹ in phosphate-boric acid buffers of pH 7, 8.5, and 10, respectively. Similar reactions in ammonium bicarbonate buffers were more than 10 times faster. With time, thomasidioic acid further converted to 2,6-dimethoxy-p-benzoquinone and 6-hydroxy-5,7-dimethoxy-2-naphthoic acid. Air oxidation of sinapic acid aqueous solutions caused darkening of the color for the system, with the 2,6-dimethoxy-p-benzoquinone as a major color contributor.     

Hydroperoxide formation during autoxidation of conjugated linoleic acid methyl ester

The aim of this study was to investigate whether hydroperoxides are formed in the autoxidation of conjugated linoleic acid (CLA) methyl ester both in the presence and absence of α‐tocopherol. The existence of hydroperoxide protons was confirmed by D₂O exchange and by chemoselective reduction of the hydroperoxide groups into hydroxyl groups using NaBH₄. These experiments were followed by nuclear magnetic resonance (NMR) spectroscopy. The ¹³C and ¹HNMR spectra of a mixture of 9‐hydroper‐oxy‐10‐trans,12‐cis‐octadecadienoic acid methyl ester (9‐OOH) and 13‐hydroperoxy‐9‐cis, 11‐trans‐octadecadienoic acid methyl ester (13‐OOH), which are formed during the autoxidation of methyl linoleate, were studied in detail to allow the comparison between the two linoleate hydroperoxides and the CLA methyl ester hydroperoxides. The ¹³CNMR spectra of samples enriched with one of the two linoleate hydroperoxide isomers were assigned using 2D NMR techniques, namely Correlated Spectroscopy (COSY), gradient Heteronuclear Multiple Bond Correlation (gHMBC), and gradient Heteronuclear Single Quantum Correlation (gHSQC). The ¹³C and ¹H NMR experiments performed in this study show that hydroperoxides are formed during the autoxidation of CLA methyl ester both in the presence and absence of α‐tocopherol and that the major isomers of CLA methyl ester hydroperoxides have a conjugated monohydroperoxydiene structure similar to that in linoleate hydroperoxides.     

Analysis of the seed oil of Heisteria silvanii (Olacaceae)—A rich source of a novel C18 acetylenic fatty acid

Besides some usual fatty acids (FA), two conjugated ene-yne acetylenic FA [trans-10-heptadecen-8-ynoic acid (pyrulic acid) (7.4%), and trans-11-octadecen-9-ynoic acid (ximenynic acid) (3.5%)], a novel ene-yne-ene acetylenic FA [cis-7, trans-11-octadecadiene-9-ynoic acid (heisteric acid) (22.6%)], and 9,10-epoxystearic acid (0.6%) could be identified in the seed oil of Heisteria silvanii (Olacaceae). Two further conjugated acetylenic FA [9,11-octadecadiynoic acid (0.1%) and 13-octadecene-9,11-diynoic acid (0.4%)] were identified tentatively by their mass spectra. The FA mixture has been analyzed by gas chromatography/mass spectrometry (GC/MS) of their methyl ester and 4,4-dimethyloxazoline derivatives. The structure of heisteric acid was elucidated after isolation via preparative silver ion thin-layer chromatography and by various spectroscopic methods [ultraviolet; infrared; ¹H, ¹³C nuclear magnetic resonance (NMR); ¹H−¹H and ¹H−¹³C correlation spectroscopy]. To determine the position of the conjugated ene-yne-ene system, the NMR spectra were also measured after addition of the lanthanide shift reagent Resolve-Al EuFOD^TM. Furthermore, the triyglyceride mixture was analyzed by high-temperature GC and high-temperature GC coupled with negative chemical ionization MS. A glass capillary column coated with a methoxy-terminated 50%-diphenyl-50%-dimethylpolysiloxane was used for the separation of the triacylglycerol (TAG) species. No evidence of decomposition of the TAG species containing conjugated ene-yne-ene FA was observed. Twenty-six species of the separated TAG were identified by means of their abundant quasi molecular ion [M−H]⁻ and their corresponding carboxylate anions [RCOO]⁻ of the fatty acids, respectively. The major molecular species of the TAG were found to be 16:0/18:1/18:1, 16:0/18:1/18:3 (heisteric acid), 17:2 (pyrulic acid)/18:1/18:1, 18:1/18:1/18:3 (heisteric acid). The TAG containing acetylenic FA showed an unexpected increase of the retention time in comparison to the TAG containing usual FA, thus making the prediction of the elution order of lipid samples containing acetylenic FA difficult.     

Synthesis and characterization of [1-13C]-and d8-arachidonic acid

Methyld ₈- and [1-¹³C] 5,8,11,14-eicosatetraenoate (arachidonate) were prepared from a common synthetic precursor, 4,7,10,13-nonadecatetrayn-1-ol. The purified products were characterized by gas chromatography-mass spectrometry. Mass spectra oft-butyldimethylsilyl esters ofd ₈-and [1-¹³C]-arachidonic acid showed a most intense [M-57]⁺ peak at high mass. The isotopic purity of methyl [1-¹³C] arachidonate was 99% and that of methyld ₈-arachidonate was 56%. Whend ₈-arachidonic acid was prepared by direct deuteration of 5,8,11,14-eicosatetraynoic acid, the isotopic purity of the sample was 86%.     

Synthesis and Characterization of Estolide Esters Containing Epoxy and Cyclic Carbonate Groups

The unsaturated sites in oleic 2‐ethylhexyl estolide esters (containing 35 % monoenic fatty acids) were converted into epoxide and five‐membered cyclic carbonate groups and the products characterized by Fourier transform infrared spectra (FTIR), ¹H, and ¹³C nuclear magnetic resonance (NMR) spectroscopies. Epoxidation of the alkene bonds was accomplished using performic acid generated in situ from formic acid and hydrogen peroxide. Greater than 90 % alkenes were converted into their corresponding epoxide groups as determined by oxirane values and the epoxide ring structure was confirmed by ¹H and ¹³C NMR. The estolide ester epoxide material was subsequently reacted with supercritical carbon dioxide in the presence of tetrabutylammonium bromide catalyst to produce the corresponding estolide ester containing the cyclic carbonate group. The signals at 1,807 cm^?1 and δ 82 ppm in the FTIR and ¹³C‐NMR spectra, respectively, confirmed the desired cyclic carbonate was produced. The carbonated estolide ester exhibited a dynamic viscosity, at 25 °C, of 172 mPa·s as compared to 155 mPa·s for the estolide ester starting material. The estolide ester structure of these new derivatives was shown to be consistent throughout their synthesis.     

Preparation and properties of conducting arachidic acid/polypyrrole composite langmuir–blodgett films

Electrically conducting arachidic acid/polypyrrole (PPy) composite films were prepared by exposing the arachidic acid LB films containing ferric chloride to pyrrole vapor. The optimum conditions to deposit matrix LB film were the subphase temperature of 23–25°C, pH of 6.0 and ferric chloride concentration of 5.0 × 10⁻⁵ M. The formation of PPy in the arachidic acid matrix LB films was confirmed by UV-visible spectra, FTIR spectra, and scanning electron micrographs. The average thickness of the composite LB films prepared at 0°C was 1525 Å. The composite films prepared at lower temperatures have more uniform surface and exhibit higher electrical conductivity than the films prepared at higher temperatures do. The in-plain conductivity and the transverse conductivity of the composite film were 10⁻³−10⁻² S/cm and 10⁻⁶S/cm, respectively, and, thus, the conductivity anisotropy was about 10³ © 1996 John Wiley & Sons, Inc.     

Structure of liquid crystalline copolyesters from two acetoxybenzoic acids and polyethylene terephthalate

The molecular and supermolecular structures of thermotropic liquid crystalline copolyesters from p-acetoxybenzoic acid (B), polyethylene terephthalate (E), and m-acetoxybenzoic acid (M) were studied by Fourier transform infrared spectrometer, 200-MHz ¹H-nuclear magnetic resonance (NMR), and wide-angle X-ray diffraction methods. The assignments of resonance peaks in NMR spectra are given and the effect of B/E/M molar ratio on the NMR spectra and number-average degree of polymerization of the copolyesters are discussed. The equatorial, meridional, and azimuthal scans, and their dependency on monomer mole ratio for the copolymers, are elaborated. The persistence length and orientation of the copolymer ribbons were found to increase with an increase in p-oxybenzoate unit content from 60 to 75 mol % at a fixed m-oxybenzoate unit content of 5 mol %. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2921–2925, 1999     

Synthesis of poly(lactic acid-b-p-dioxanone) block copolymers from ring opening polymerization of p-dioxanone by poly(L-lactic acid) macroinitiators

Poly(lactic acid-b-p-dioxanone) block copolymers (P(LA-b-PDO)) were synthesized by ring-opening polymerization of p-dioxanone using poly(lactic acid) (PLA) with different molecular weights as macroinitiators in N₂ atmosphere. The copolymers were characterized by ¹H-NMR spectra. The thermal and crystalline behaviors and thermal stability of these copolymers were investigated by DSC, TGA and WAXD. The results indicated that the contents of each segment and the intrinsic viscosities affected the properties of copolymers obviously.     

Synthesis and characterization of some long-chain diesters with branched or bulky moieties

Several novel fatty diesters with bulky moieties were synthesized by esterification of mono- or bifunctional fatty acids or with mono- or bifunctional alcohols using p-toluenesulfonic acid as catalyst. They were characterized by ¹H and ¹³C nuclear magnetic resonance as well as positive chemical ionization (PCl) mass spectrometry. The PCl mass spectra of the resulting diol diesters and diacid diesters are discussed and compared. The compounds were investigated as potential additives for improving the cold flow properties of vegetable oil esters used as biodiesel. Retired.     

NMR characterization of dihydrosterculic acid and its methyl ester

Cyclopropane FA occur in nature in the phosphoplipids of bacterial membranes, in oils containing cyclopropene FA, and in Litchi sinensis oil. Dihydrosterculic acid (2-octyl cyclopropaneoctanoic acid) and its methyl ester were selected for ¹H and ¹³C NMR analysis as compounds representative of cyclopropane FA. The 500 MHz ¹H NMR spectra acquired with CDCl₃ as solvent show two individual peaks at −0.30 and 0.60 ppm for the methylene protons of the cyclopropane ring. Assignments were made with the aid of 2D correlations. In accordance with previous literature, the upfield signal is assigned to the cis proton and the downfield signal to the trans proton. This signal of the trans proton is resolved from the peak of the two methine protons of the cyclopropane ring, which is located at 0.68 ppm. The four protons attached to the two methylene carbons α to the cyclopropane ring also show a split signal. Two of these protons, one from each methylene moiety, display a distinct shift at 1.17 ppm, and the signal of the other two protons is observed at 1.40 ppm, within the broad methylene peak. The characteristic peaks in the ¹³C spectra are also assigned.     

Regioisomers of octanoic acid-containing structured triacylglycerols analyzed by tandem mass spectrometry using ammonia negative ion chemical ionization

Tandem mass spectrometry based on ammonia negative ion chemical ionization and sample introduction via direct exposure probe was applied to analysis of regioisomeric structures of octanoic acid containing structured triacylglycerols (TAG) of type MML, MLM, MLL, and LML (M, medium-chain fatty acid; L, long-chain fatty acid). Collision-induced dissociation of deprotonated parent TAG with argon was used to produce daughter ion spectra with appropriate fragmentation patterns for structure determination. Fatty acids constituting the TAG molecule were identified according to [RCO₂]⁻ ions in the daughter ion spectra. With the standard curve for ratios of [M-H-RCO₂H-100]⁻ ions corresponding to each [RCO₂]⁻ ion, determined with known mixtures of sn-1/3 and sn-2 regioisomers of structured TAG, it was possible to determine the proportions of different regioisomers in unknown samples. The method enabled quantification of MML- and MLM-type structured TAG. In the case of MLL- and LML-type TAG, it was possible to determine the most abundant regioisomer in the unknown mixture and estimate the proportions of regioisomers when there were more than 50% MLL-type isomers in the mixture.     

Methyl Esters (Biodiesel) from and Fatty Acid Profile of Gliricidia sepium Seed Oil

Increasing the supply of biodiesel by defining and developing additional feedstocks is important to overcome the still limited amounts available of this alternative fuel. In this connection, the methyl esters of the seed oil of Gliricidia sepium were synthesized and the significant fuel‐related properties were determined. The fatty acid profile was also determined with saturated fatty acids comprising slightly more than 35 %, 16.5 % palmitic, 14.5 % stearic, as well as lesser amounts of even longer‐chain fatty acids. Linoleic acid is the most prominent acid at about 49 %. Corresponding to the high content of saturated fatty acid methyl esters, cold flow is the most problematic property as shown by a high cloud point of slightly >20 °C. Otherwise, the properties of G. sepium methyl esters are acceptable for biodiesel use when comparing them to specifications in biodiesel standards but the problematic cold flow properties would need to be observed. The ¹H‐ and ¹³C‐NMR spectra of G. sepium methyl esters are reported.     

Characterization of pedicel,paper, and larval silk from nest ofPolistes annularis (L.)

The pedicel, nest paper, and larval silk ofPolistes annularis nests were analyzed by high-resolution solid-state [¹³C]NMR. The pedicel was found to have a high nitrogen content (11%), and the NMR spectra indicated that it is a mixture of carbohydrate and protein. The pedicel protein has an amino acid composition that is very rich in glycine, alanine, serine, and proline (67% of identified residues), similar to that of some insect silks. Solid-state [¹³C]NMR indicated that the nest paper is composed predominantly of cellulose. Silk, spun by matureP. annularis larvae, was shown by [¹³C] NMR and amino acid analysis to be a protein very high in serine and alanine (53%), but the amino acid composition is distinct from that of the pedicel protein.     

NMR Study on the Acidity of TS-1 Zeolite

The acidic properties of TS-1 and Silicalite-1 zeolites have been investigated by the solid-state MAS NMR technique capable of in situ sample pretreatment. As shown by a combination of the ³¹P MAS NMR and ¹H MAS NMR techniques with trimethylphosphine, not only Brønsted acid sites but also Lewis acid sites exist in the TS-1 zeolites. Moreover, TS-1 zeolite is more acidic compared with Silicalite-1. The ¹H, ²⁹Si MAS NMR spectra and the resonance related to Brønsted acid species in the ³¹P MAS NMR spectra demonstrate clearly that the presence of titanium in the framework results in the formation of a new hydroxy group, titanols, which is more acidic than silanols of Silicalite-1. The ³¹P MAS NMR measurements also illustrate convincingly the existence of at least two different Lewis acid species on the TS-1 zeolites. The conversion of propylene oxide into methoxypropanol catalyzed by TS-1 or Silicalite-1 zeolite in methanol solution as a test reaction has also been described. With the increase of titanium in zeolite, TS-1 appears to have a higher activity during the reaction of propylene oxide to methoxypropanol.