Identification and confirmation of traces of chlorinated fatty acids in fish downstream of bleached kraft pulp mills by gas chromatography with halogen-specific detection

Methyl esters of threo-9,10-dichlorooctadecanoic, threo-7,8-dichlorohexadecanoic, and threo-5,6-dichlorotetradecanoic acids, present in transesterified extracts of filets, gonad, intestinal fat and carcass of white sucker (Catostomus commersoni) sampled in receiving waters of bleached kraft pulp mill effluents, were identified by gas chromatography with halogen-specific detection (XSD). Identification was based on (1) a comparison of the retention times of a sample peak with a prospective reference standard on two stationary phases of very different polarities by spiking, and (2) elution behavior of configurational and positional isomers of dichloro fatty acid methyl esters.     

Structural characterization of 5,6-dichlorotetradecanoic acid, an isolated metabolite of 9,10-dichlorooctadecanoic acid, by studying picolinyl esters, pyrrolidides and methyl esters with electron ionization mass spectrometry

A method is presented for identification of positional isomers of dichlorinated fatty acids, based on derivatization to picolinyl esters prior to gas chromatographic/mass spectrometric analysis in the electron ionization mode. The mass spectra of the picolinyl esters showed structure-specific fragmentation patterns. By using the picolinyl ester, 5,6-dichlorotetradecanoic acid was identified as a metabolite from a cell-culture medium obtained by culturing human cell lines in media supplemented with threo-9,10-dichlorooctadecanoic acid. This indicates that dichlorinated fatty acids are degraded by beta-oxidation. It is also possible to locate tentatively the position of chlorine atoms in 5,6-dichlorotetradecanoic acid as its methyl ester or pyrrolidide.     

The effect of eucalypt pulp xylan content on its bleachability,refinability and drainability

Currently, bleached eucalypt pulps are largely used for printing and writing (P&W) and sanitary (tissue) paper grades. Among the many pulp quality requirements for P&W and tissue paper production the xylan content is one of the most significant. For P&W papers, increasing xylans improve pulp refinability and strength properties but negatively affect bulk and drainability. For tissue paper, xylans are purportedly advantageous during paper drying in the Yankee cylinder but negatively affect paper bulk and may increase dusting during paper manufacture. On the other hand, bleachability is a very important parameter for both P&W and tissue grade pulps since bleaching cost is the second most significant in eucalypt bleached kraft pulp production. The aim of this study was evaluating the influence of eucalyptus pulp xylan content on its bleachability, refinability and drainability. A sample of industrial unbleached eucalyptus kraft pulp containing 15.6?% xylans was treated with various alkali charges at room temperature in order to obtain materials with different xylan contents. The pulps were bleached to 90 % ISO brightness with the O–D_HT–(EP)–D sequence and evaluated for their refinability and drainability. By increasing the alkali concentration in the range of 10–70 g/L pulps of 14.5–5.9 % xylans were produced with no significant impact on cellulose crystallinity. The decrease of xylan content significantly decreased pulp bleaching chemical demand, water retention value and refinability and increased pulp drainability.     

Analysis of cellulose and kraft pulp ozonolysis products by anion-exchange chromatography with pulsed amperometric detection

Efforts to reduce the level of chlorinated organics discharged into the environment have led to interest in ozone bleaching of kraft pulp. In the course of this operation the transformation of cellulose has to be reduced to the minimum. With this aim, the investigation of the cellulose—ozone reaction was carried out from a mechanistic point of view. The initial interest was in the composition of kraft pulp and cellulose ozonation effluents. High-performance anion-exchange chromatography with pulsed amperometric detection was used to separate and partially identify the soluble modified or unmodified carbohydrates of kraft pulp and cellulose ozonolysis. The main results indicate that after ozonation at 0, 25 and 65°C, cellulose gives oligosaccharides, monosaccharides and probably oxidized forms of those products. Formaldehyde was also directly determined under the same conditions as for carbohydrates.     

Identification of chlorinated fatty acids in fish by gas chromatography/mass spectrometry with negative ion chemical ionization of pentafluorobenzyl esters

This paper reports the development of a technique for identifying and confirming chlorinated fatty acids previously detected in fish by gas chromatography (GC) with halogen-specific detection (XSD). Fatty acid methyl esters (FAMEs) including chlorinated FAMEs within fractions of reversed-phase high-performance liquid chromatography of transesterified fish extracts were derivatized to pentafluorobenzyl esters, which were subjected to GC/mass spectrometry (MS) with negative ion chemical ionization (NICI). Pentafluorobenzyl esters displayed reasonably good GC characteristics, a very high ionization efficiency and a low degree of fragmentation. Chloride ion chromatograms extracted at m/z 35 and 37 from full scans were utilized for locating traces of chlorinated unknowns in the GC elution profile so that their mass spectra could be readily displayed. Significant ions displayed in the mass spectrum scanned in a narrow range of retention time where a chlorinated unknown was located were evaluated using ion chromatograms extracted at the m/z of these ions. The chromatographic peaks of those ions derived from the analyte were expected to center at that specific retention time, whereas those originating from matrix compounds were not. The isotopic patterns of chlorinated ions were also examined against their theoretical relative abundances. Using this approach, three metabolism-related dichloro fatty acids previously identified by GC/XSD in filet extracts of white sucker sampled downstream from a bleached kraft pulp mill were confirmed: dichlorooctadecanoic, dichlorohexadecanoic and dichlorotetradecanoic acids. In addition, an isomer of dichlorotetradecanoic acid was found in a reference fish sample. As sample preparation is critical in this application, improved conditions for hydrolysis and pentafluorobenzyl esterification are also discussed.     

On the accessibility and structure of xylan in birch kraft pulp

The structure of -(14)-xylan, both in isolated form and as a component of bleached birch kraft pulp, was studied employing CP/MAS ¹³C NMR spectroscopy. Bleached birch kraft pulp was treated with xylanases or alkali in order to distinguish between accessible and inaccessible xylan. In xylan which was alkali-extracted from bleached birch kraft pulp, the relative contents of xylose and 4-O-methylglucuronic acid were 99.4 and 0.6 weight %, respectively, and the degree of polymerization was 70. The supermolecular structure of xylan is very sensitive to the surrounding environment. All extracted xylan chains were accessible to water and methanol and the solvent molecules easily exchanged. In bleached birch kraft pulp, cellulose fibrils interact with xylan chains, causing these to adopt a conformation similar to one of the configurations observed for dry xylan. In birch pulp, about 1/3 of the xylan was found to be accessible to digestion by xylanases or extraction with 5% w/w potassium hydroxide (aq). A signal at 81.7ppm in the C-4 region of the CP/MAS ¹³C NMR spectrum of bleached birch kraft pulp originated from xylan at the accessible fibril surfaces. A portion of a broad signal at 83.5ppm reflected inaccessible xylan, which is probably present as co-aggregates with cellulose fibril aggregates.     

Effect of Glucuronoxylan on the Hornification of Eucalyptus globulus Bleached Pulps

The effect of 4-O-methylglucuronoxylan (GX) on the hornification of bleached kraft and acid sulphite Eucalyptus globulus chemical pulps has been investigated. Almost straight-line dependence of kraft pulp hornification from GX content was explained through the diminishing of fibrils aggregation and better accessibility of amorphous cellulose regions to water in GX enriched pulps. The higher hornification of sulphite than kraft pulp was assigned to lower GX content in the former and to unfavourable rearrangement of cellulose molecules in crystalline and amorphous regions during acid sulphite pulping.     

Metabolism of Deuterated threo‐Dihydroxy Fatty Acids in Saccharomyces cerevisiae: Enantioselective Formation and Characterization of Hydroxylactones and γ‐Lactones

Biotransformation of (±)‐threo‐7,8‐dihydroxy(7,8‐²H₂)tetradecanoic acids (threo‐(7,8‐²H₂)‐ 3 ) in Saccharomyces cerevisiae afforded 5,6‐dihydroxy(5,6‐²H₂)dodecanoic acids (threo‐(5,6‐²H₂)‐ 4 ), which were converted to (5S,6S)‐6‐hydroxy(5,6‐²H₂)dodecano‐5‐lactone ((5S,6S)‐(5,6‐²H₂)‐ 7 ) with 80% e.e. and (5S,6S)‐5‐hydroxy(5,6‐²H₂)dodecano‐6‐lactone ((5S,6S)‐5,6‐²H₂)‐ 8 ). Further β‐oxidation of threo‐(5,6‐²H₂)‐ 4 yielded 3,4‐dihydroxy(3,4‐²H₂)decanoic acids (threo‐(3,4‐²H₂)‐ 5 ), which were converted to (3R,4R)‐3‐hydroxy(3,4‐²H₂)decano‐4‐lactone ((3R,4R)‐ 9 ) with 44% e.e. and converted to ²H‐labeled decano‐4‐lactones ((4R)‐(3‐²H₁)‐ and (4R)‐(2,3‐²H₂)‐ 6 ) with 96% e.e. These results were confirmed by experiments in which (±)‐threo‐3,4‐dihydroxy(3,4‐²H₂)decanoic acids (threo‐(3,4‐²H₂)‐ 5 ) were incubated with yeast. From incubations of methyl (5S,6S)‐ and (5R,6R)‐5,6‐dihydroxy(5,6‐²H₂)dodecanoates ((5S,6S)‐ and (5R,6R)‐(5,6‐²H₂)‐ 4a ), the (5S,6S)‐enantiomer was identified as the precursor of (4R)‐(3‐²H₁)‐ and (2,3‐²H₂)‐ 6 ). Therefore, (4R)‐ 6 is synthesized from (3S,4S)‐ 5 by an oxidation/keto acid reduction pathway involving hydrogen transfer from C(4) to C(2). In an analogous experiment, methyl (9S,10S)‐9,10‐dihydroxyoctadecanoate ((9S,10S)‐ 10a ) was metabolized to (3S,4S)‐3,4‐dihydroxydodecanoic acid ((3S,4S)‐ 15 ) and converted to (4R)‐dodecano‐4‐lactone ((4R)‐ 18 ).     

Studies Related to Biological Detoxification of Kraft Pulp Mill Effluent. IV.The Biodegradation of 14-Chlorodehydroabietic Acid with Mortierella isabellina

One of the fish-toxic chlorinated resin acids, 14-chlorodehydroabietic acid ( 5 ), found in kraft mill effluent is examined. When exposed to the fungus Mortierella isabellina, 5 is converted into a number of hydroxylated derivatives which show low levels of toxicity to fish. These biotransformation products were isolated and characterized.     

Determination of xylo-oligosaccharides in enzymatically hydrolysed pulp by liquid chromatography and capillary electrophoresis

Three different commercial β-1,4-endoxylanase preparations were used to hydrolyze bleached kraft pulp. Xylo-oligosaccharides in the produced filtrates were separated and quantified using both high performance liquid chromatography (HPLC) and capillary electrophoresis (CE). All the determinations were performed without sample derivatization. The analytical methods were used to highlight the differences between the enzymes behaviour in terms of hydrolysates, but also to estimate the productivity of xylo-oligosaccharides from kraft pulp when the bleached material would be used in biorefining industry. The research showed that the glycosyl hydrolase family 10 enzyme produced by Aspergillus oryzae released xylobiose and xylotriose from the pulp material. The major oligosaccharides released by the family 11 enzyme produced by Bacillus sp. were xylotriose, xylobiose and xylotetraose. On the contrary, another family 11 enzyme produced by A. oryzae produced also xylose. The HPLC results agreed well with the xylose concentrations obtained after acid hydrolysis. The CE data showed the same trend, but much lower concentrations were identified than with HPLC. At the same time the HPLC method was able to separate only small oligosaccharides, whereas CE could be used for separation of all the xylo-oligosaccharides from xylobiose to xylohexaose. The highest xylo-oligosaccharide yield was achieved with Shearzyme at pH 5 corresponding to 22 % of total xylan from bleached birch kraft pulp.     

Sorption of spruce O-acetylated galactoglucomannans onto different pulp fibres

Sorption of spruce acetylated galactoglucomannans (GGM) onto different pulps, among which unbleached and peroxide-bleached mechanical pulps, and unbleached and bleached kraft (BK) pulps, was studied as a means of understanding the retention of acetylated GGMs in mechanical pulping and papermaking. The fibre surface coverage of lignin and carbohydrates was estimated by X-ray photoelectron spectroscopy (XPS) or electron spectroscopy for chemical analysis (ESCA). GGM sorption was clearly favoured on kraft pulps. Hardly any differences in sorption were, however, observed between unbleached and BK pulps, even if the surface coverage of lignin was lower on the bleached pulp. Neither thermomechanical pulp (TMP) nor chemithermomechanical pulp (CTMP) manufactured from spruce sorbed any acetylated GGMs. Peroxide bleaching of the pulp did not increase sorption. Only CTMP produced from aspen sorbed some GGMs. The anionic charge of neither chemical nor mechanical pulps influenced GGM sorption.     

Potential of Thermo and Alkali Stable Xylanases from Thielaviopsis basicola (MTCC-1467) in Biobleaching of Wood Kraft Pulp

Thermo- and alkali-stable xylanases produced from Thielaviopsis basicola (MTCC-1467) on low-cost carbon source like rice straw were evaluated for their potential application in biobleaching of wood kraft pulp. Enzyme treatment at retention time of 240?min with 20?IU/gm of dried pulp resulted in ~85.2?% of reduction in kappa number. When compared to control, 110.8, 93, and 72.2?% of enhancement in brightness (percent International Organization of Standardization), whiteness, and fluorescence, respectively, were observed for enzyme-treated pulp. Spectroscopic analysis showed significant release of chromophoric compounds from enzyme-treated pulp. Furthermore, scanning electron microscope studies of unbleached and enzyme bleached pulp revealed the effectiveness of enzymatic treatment. The enzyme-treated pulp subjected to later stages of chemical bleaching resulted in 16?% decrease in chlorine consumption along with considerable reduction in chemical oxygen demand percentage (14.5?%) level of effluent. Various pulp properties like fiber length, fiber width, burst strength, burst index, tear strength, tear index, tensile strength, and breaking length were also significantly improved after enzyme treatment when compared to control.     

Analysis of precipitated lignin on kraft pulp fibers using atomic force microscopy

A method is presented which enables analysis of lignin precipitated on the surface of kraft pulp fibers. As experimental input, high-resolution atomic force microscopy phase images of the fiber surfaces have been recorded in tapping mode. A digital image analysis procedure—based on the watershed algorithm—is applied to distinguish between cellulose fibrils and the precipitated lignin. In this way, size distributions for the diameter of lignin precipitates on pulp fiber surfaces can be obtained. In an initial application of the method, three softwood kraft pulps were analyzed: a black liquor cook with a very high content of precipitated lignin, a bleached pulp where nearly no precipitated lignin is visible and an unbleached industrial pulp. The proposed method is suggested as an appropriate tool to investigate the kinetics of lignin precipitation and the structure of lignin precipitates in pulping and bleaching.     

Chlorination of trans-1,2-Diarylethenes in Chloroform and Acetic Acid

When chlorinated in chloroform, (E)-stilbenes bearing electron-donor substituents in the para position of the benzene ring give threo-1,2-diaryl-1,2-dichloroethanes, while meta-substituted (E)-stilbenes, predominantly erythro isomers, irrespective of the nature of the substituent. The reactions in acetic acid result in preferential formation of threo-1,2-dichloro- and threo-1-acetoxy-1,2-diaryl-2-chloroethanes.     

Synthesis and structure of new 6-substituted 5-methyl-5,6-dihydrocyclohepta[<Emphasis Type="Italic">b</Emphasis>]indole-9,10-dicarboxylic anhydrides

Reactions of (2-chloro-1-methyl-1H-indol-3-yl)-2-oxoacetyl chloride with alk-3-enoic acids gave the corresponding 6-substituted 5-methyl-5,6-dihydrocyclohepta[b]indole-9,10-dicarboxylic anhydrides which showed fluorescent properties.     

Ionic liquid extraction method for upgrading eucalyptus kraft pulp to high purity dissolving pulp

High purity cellulose from wood is an important raw material for many applications such as cellulosic fibers, films or the manufacture of various cellulose acetate products. Hitherto, multi-step refining processes are needed for an efficient hemicellulose removal, most of them suffering from severe cellulose losses. Recently, a novel method for producing high purity cellulose from bleached paper grade birch kraft pulp was presented. In this so called IONCELL process, hemicelluloses are extracted by an ionic liquid–water mixture and both fractions can be recovered without yield losses or polymer degradation. Herein, it is demonstrated that bleached Eucalyptus urograndis kraft pulp can be refined to high purity acetate grade pulp via the IONCELL process. The hemicellulose content could be reduced from initial 16.6 to 2.4 wt% while persevering the cellulose I crystal form by using an optimized 1-ethyl-3-methylimidazolium dimethylphosphate-water mixture as the extraction medium. The degree of polymerization was then reduced by a sulfuric acid treatment for subsequent acetylation of the pulp, resulting in a final hemicellulose content of 2.2 wt%. When pre-treating the pulp enzymatically with endoxylanase, the final hemicellulose content could be reduced even to 1.7 wt%. For comparison, the eucalyptus kraft pulp was also subjected to cold caustic extraction and the same subsequent acid treatment which led to 3.9 wt% of residual hemicelluloses. The performance in acetylation of all produced pulps was tested and compared to commercial acetate grade pulp. The endoxylanase-IONCELL-treated pulp showed superior properties. Thus, an ecologically and economically efficient alternative for the production of highest value cellulose pulp is presented.     

Adducts of phenanthrene 9,10-imine and of benz[a]anthracene 5,6-imine to some nitrogen heterocycles

N-4-Pyridinyl-, N-2-quinolinyl-, and 2-pyrazinylphenanthrene 9,10-imines 4–6 , as well as N-4-pyridinyl- and N-2-pyrazinylbenz[a]anthracene 5,6-imines 12 and 13 were prepared by sodium hydride-mediated interaction of the parent arene imines, 1 and 10 , and the respective chloropyridine, chloroquinoline or chloropyrazine. N-Nicotynoyl-, N-2-pyridinoyl- and N-6-quinolinoylphenanthrene 9,10-imines 7–9 were obtained by interaction of N-trimethylsilylphenanthrene 9,10-imine ( 2 ) and the appropriate pyridine- or quinolinecarbonyl chlorides. Reaction of N-methylsulfonylphenanthrene 9,10-imine with thymine, cytosine, 5-fluorocytosine, purine, 6-chloropurine and adenine afforded, in the presence of either potassium carbonate or 1,5-diazabicyclo[3.4.0]non-5-ene, adducts 16–22 , respectively. The structures of the adducts were conformed by multinuclear nmr and by NOESY and C-H correlation 2D nmr spectrometry.     

SEC-MALLS analysis of softwood kraft pulp using LiCl/1,3-dimethyl-2-imidazolidinone as an eluent

Various cellulose and pulp samples including softwood bleached kraft pulp (SBKP) were dissolved in 8% lithium chloride/1,3-dimethyl-2-imidazolidinone (LiCl/DMI) and 8% LiCl/N,N-dimethylacetamide (DMAc), and the obtained solutions were subjected to size-exclusion chromatographic analysis with multi-angle light scattering detection (SEC-MALLS). Although SBKP was not completely soluble in 8% LiCl/DMAc, 1% LiCl/DMI always gave a clear solution of SBKP without centrifugation. Molecular mass (MM) and MM distribution measurements using 1% LiCl/DMI as an eluent for the SEC-MALLS analysis revealed that SBKP had MM higher than those of the other cellulose and pulp samples at the same elution volume. The slope of the conformation plots for SBKP showed an anomalously low value of 0.41, while those for other cellulose and pulp samples were in the range of 0.57–0.59, which corresponds to the normal random coil conformations. These results indicate that some compact structures like branches or cross-linkages other than molecular-dispersed states are present in the high MM region of SBKP, which can be detected when the LiCl/DMI solvent system is used as the solvent as well as the eluent for the SEC-MALLS analysis. On the other hand, no such structures were observed for the other cellulose and pulp samples including softwood bleached sulfite pulps. Thus, the compact structures present in SBKP are likely to be susceptible to acid treatments.     

Conformational study of methyl esters of some aliphatic erythro- and threo-dichlorocarboxylic acids

The average conformations of methyl esters of some aliphatic erythro- and threo-dichlorocarboxylic acids in dilute carbon tetrachloride solutions have been determined from the vicinal proton–proton coupling constants and ¹H NMR shifts. The ¹³C shift differences between the erythro and threo forms are compared and discussed with regard to the differences in the average conformations.     

Measurement of the flexibility of wet cellulose fibres using atomic force microscopy

Flexibility and modulus of elasticity data for two types of wet cellulose fibres using a direct force–displacement method by means of AFM are reported for never dried wet fibres immersed in water. The flexibilities for the bleached softwood kraft pulp (BSW) fibres are in the range of 4–38 × 10¹² N^?1 m^?2 while the flexibilities for the thermomechanical pulp (TMP) fibres are about one order of magnitude lower. For BSW the modulus of elasticity ranges from 1 to 12 MPa and for TMP between 15–190 MPa. These data are lower than most other available pulp fibre data and comparable to a soft rubber band. Reasons for the difference can be that our measurements with a direct method were performed using never dried fibres immersed in water while other groups have employed indirect methods using pulp with different treatments.