Increasing Carbon Chain Length Research Articles

The Synthesis and Properties of 3-(2'-Benzothiazolyl)coumarin Fluorescent Dyes for Polyester Fabrics

Fluorescent dyes based on 3-(2'-benzothiazolyl)coumarin were synthesized by a simple condensing reaction in this study. The chemical structures of synthesized compounds were subjected to FT-IR, 1H-NMR, Mass and UV/Vis analysis for color characteristics. Polyester fabrics dyed with the compounds were evaluated by color strength and color fastness to washing, perspiration and light of ISO. The results showed that all dyes decide after identified by IR, MS and 1H-NMR the structure is correct. And then all dyes were used to the dyeing of polyester fabrics. It was clearly that color strength increased with the increasing of the amount of carbon in the 7-position of coumarin ring. The level of color fastness to washing and perspiration were 4-5 or more, while the level of color fastness to light decreased with an increase of carbon chain length.

Toxicity of fluorotelomer carboxylic acids to the algae Pseudokirchneriella subcapitata and Chlorella vulgaris, and the amphipod Hyalella azteca

Perfluorinated acids (PFAs) have elicited significant global regulatory and scientific concern due to their persistence and global pervasiveness. A source of PFAs in the environment is through degradation of fluorotelomer carboxylic acids (FTCAs) but little is known about the toxicity of these degradation products. Previous work found that FTCAs were two to three orders of magnitude more toxic to some freshwater invertebrates than their PFA counterparts and exhibited comparable chain-length–toxicity relationships. In this study, we investigated the toxicity of the 6:2, 8:2, and 10:2 saturated (FTsCA) and unsaturated (FTuCA) fluorotelomer carboxylic acids to two species of freshwater algae, Chlorella vulgaris and Pseudokirchneriella subcapitata, and the amphipod, Hyalella azteca. C. vulgaris was generally the most sensitive species, with EC 50s of 26.2, 31.8, 11.1, and 4.2 mg/L for the 6:2 FTsCA, 6:2 FTuCA, 8:2 FTuCA, and 10:2 FTsCA, respectively. H. azteca was most sensitive to the 8:2 FTsCA and 10:2 FTuCA, with LC 50s of 5.1 and 3.7 mg/L. The toxicity of the FTCAs generally increased with increasing carbon chain length, and with saturation for most of the species tested, with the exception of P. subcapitata, which did not exhibit any trend. These observations agree with chain-length–toxicity relationships previously reported for the PFCAs and support the greater toxicity of the FTCAs compared to PFCAs. However, the toxicity values are approximately 1000-fold above those detected in the environment indicating negligible risk to aquatic invertebrates.

An experimental study of gas void fraction in dilute alcohol solutions in annular gap bubble columns using a four-point conductivity probe

The influence of alcohol concentration on the gas void fraction in open tube and annular gap bubble columns has been investigated using a vertical column with an internal diameter of 0.102 m, containing a range of concentric inner tubes, which formed an annular gap; the inner tubes had diameter ratios from 0.25 to 0.69. Gas (air) superficial velocities in the range 0.014–0.200 m/s were investigated. Tap water and aqueous solutions of ethanol and isopropanol, with concentrations in the range 8–300 ppm by mass, were used as the working liquids. Radial profiles of the local void fraction were obtained using a four-point conductivity probe and were cross-sectionally averaged to give mean values that were within 12% of the volume-averaged gas void fractions obtained from changes in the aerated level. The presence of alcohol inhibited the coalescence between the bubbles and consequently increased the mean gas void fraction at a given gas superficial velocity in both the open tube and the annular gap bubble columns. This effect also extended the range of homogeneous bubbly flow and delayed the transition to heterogeneous flow. Moreover, isopropanol results gave slightly higher mean void fractions compared to those for ethanol at the same mass fraction, due to their increased carbon chain length. It was shown that the void fraction profiles in the annular gap bubble column were far from uniform, leading to lower mean void fractions than were obtained in an open tube for the same gas superficial velocity and liquid composition.

Enhanced chemiluminescence of peroxomonosulfate–cobalt (II) system in the presence of dicarboxylic acids

In the present work, the effects of molecular mass aliphatic dicarboxylic acids on the HSO(5)(-)-Co(2+) chemiluminescence (CL) system were investigated. It was found that the aliphatic dicarboxylic acids could enhance the CL of the HSO(5)(-)-Co(2+) system. Moreover, the CL intensities improved regularly with increasing carbon chain length of the dicarboxylic acids. To investigate the CL enhancement mechanism, dynamic profiles, CL spectroscopy, ESR spectrum and the effects of various free radical scavengers on the CL system were employed. The results indicated that the enhancement of the CL should be attributed to the formation of peroxo-diacid, which finally decomposed to the original dicarboxylic acid and singlet oxygen. The mechanism of the HSO(5)(-)-Co(2+)-dicarboxylic acid CL system was then proposed.

Synthesis of mesoporous ZnS synergistically templated by butylamine and alkanols

Pore size and pore volume adjustable mesoporous ZnS was synthesized through a co-template method, which was achieved by the combined interaction between butylamine and some alkanols with proper lengths of the straight carbon chain. The pore size for mesoporous ZnS templated by butyl amine alone was 4.29 nm, and could be enlarged to 6.96 and 8.33 nm respectively through adding certain amounts of hexanol and octanol. Correspondingly, the pore volume also exhibited an augmentation with increasing carbon chain lengths of alkanols from C 6 to C 8. However, the pore size and pore volume dropped abruptly when decanol was added as the auxiliary agent. The formation of mesopores for ZnS prepared using butylamine molecules as the only templating agent is considered to be attributed to the coordination between N atoms in amines and Zn 2+ ions at the surfaces of zinc suphide. The templating effect of butylamines might be improved by adding hexanols and octanols to form aggregates through solubilization to tailor the pore size and pore volume of ZnS effectively, while the function of decanols for changing the porous structure is restricted by its low solubility.

Synthesis of short chain alkyl esters using cutinase from Burkholderia cepacia NRRL B2320

Short chain alkyl esters are well appreciated for fruity flavors they provide. These are mainly applied to the fruit-flavored products like jam, jelly, beverages, wine and dairy. Cutinase from Burkholderia cepacia NRRL B 2320 was found to be active in catalyzing the synthesis of alkyl esters in organic solvent. The optimal temperature range for the enzyme catalyzed synthesis was found to be from 35 °C to 40 °C. The maximum conversion (%) during synthesis of ester was obtained for butyric acid (C4) and valeric acid (C5) with butanol reflecting the specificity of the enzyme for short-chain length fatty acids. In case of alcohol specificity, butanol was found to be most preferred substrate by the enzyme and conversion (%) decreased with increasing carbon chain length of alcohol used in the esterification reaction. The kinetic analysis for the synthesis of butyl butyrate by varying concentration of one substrate at a time (butanol or butyric acid), showed that Ping–Pong Bi Bi model with acid inhibition and influence of initial water is most suitable model for the prediction of the reaction kinetics.

Analyses of sulfonamide antibiotics in meat samples by on-line concentration capillary electrochromatography–mass spectrometry

In this work, a series of poly(divinylbenzene-alkyl methacrylate) monolithic stationary phases, which were prepared by single step in situ polymerization of divinylbenzene and various alkyl methacrylates (butyl-, octyl-, lauryl- or stearyl methacrylate), were developed as separation columns of nine common sulfonamide antibiotics for capillary electrochromatography (CEC) coupled to mass spectrometry (MS). Results indicated that the sulfonamide's retention became weak with increased carbon chain length of alkyl methacrylate monomer (for example, t R = 68 min and 21 min for butyl- and lauryl methacrylate, respectively). Among them, the poly(divinylbenzene-octyl methacrylate) (poly(DVB-OMA)) monolith was regarded as the optimal separation column as this provided better resolution within the shortest retention time. Moreover, the cross-sectional roughness of the monolithic column-end, that was used to couple to the ESI interface, strongly influenced the electrospray stability in the CEC–MS. Before the column was connected to the ESI-MS, a simple polishing was done to reduce the roughness of the column end that resulted to a great improvement in the signal stability. The relative standard deviations (RSDs) of the peak areas for the unpolished and polished ends of the poly(DVB-OMA) columns ( n = 5) were in the range of 46.1–60.2% and 8.9–16.4%, respectively. Furthermore, optimization of the mobile phase composition and the gradient elution strategy successfully determined the sulfonamide antibiotics in meat samples with as low as 10 μg/L level.

Organic solvents vapor pressure and relative humidity effects on the phase transition rate of α and β forms of tegafur

The objective of this work was to investigate the relative humidity (RH) and solvent vapor pressure effects on the phase transition dynamics between tegafur polymorphic forms that do not form hydrates and solvates. The commercially available α and β modifications of 5-fluoro-1-(tetrahydro-2-furyl)-uracil, known as the antitumor agent tegafur, were used as model materials for this study. While investigating the phase transitions of α and β tegafur under various partial pressures of methanol, n-propanol, n-butanol, and water vapor, it was determined that the phase transition rate increased in the presence of solvent vapors, even though no solvates were formed. By increasing the relative air humidity from 20% to 80%, the phase transition rate constant of α and β tegafur was increased about 60 times. After increasing the partial pressure of methanol, n-propanol, or n-butanol vapor, the phase transition rate constant did not change, but the extent of phase transformation was increased. In the homologous row of n-alcohols, the phase transition rate constant decreased with increasing carbon chain length. The dependence of phase transformation extent versus the RH corresponded to the polymolecular adsorption isotherm with a possible capillary condensation effect.

Stability of Heterochiral Hybrid Membrane Made of Bacterial sn-G3P Lipids and Archaeal sn-G1P Lipids

The structure of membrane lipids in Archaea is different from those of Bacteria and Eucarya in many ways including the chirality of the glycerol backbone. Until now, heterochiral membranes were believed to be unstable; thus, no cellular organism could have existed before the separation of the groups of life. In this study, we tested the formation of heterochiral hybrid membrane made of Bacterial sn-glycerol-3-phosphate-type polar lipid and Archaeal sn-glycerol-1-phosphate-type polar lipid using the fluorescence probe. The stability of the hybrid liposomes made of phosphatidylethanolamines or phosphatidylcholines or polar lipids of thermophilic Bacteria and polar lipids of Archaea were investigated. The hybrid liposomes are all stable compared with homochiral liposome made of dimyristoylphosphatidylethanolamine and dipalmitoylphosphatidylcholine. However, the stability was drastically changed with increasing carbon chain length. Accordingly, "chirality" may not be but chain length is important. From these results, we suggest that the heterochiral hybrid membrane could be used as the membrane lipid for the last universal common ancestor (Commonote) before the emergence of Archaea and Bacteria.

Model Studies on Volatile Release from Different Semisolid Fat Blends Correlated with Changes in Sensory Perception

The effect of dispersed aqueous droplets in water-in-oil (W/O)-emulsion semisolid fats on aroma release and sensory perception was investigated on margarine models where model aroma substances were added. Aroma release from W/O-emulsion fat blends and bulk fat blends with added monoglycerides combining different fatty acids of various short-chain free fatty acids, methylketones, esters, and lactones were measured using headspace solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS), and their perception profiles were evaluated by sensory analysis. The presence of aqueous phase in a fat blend significantly reduced the headspace concentrations of butanoic acid and hexanoic acid, and also decreased the perceived intensity of total aroma and cheesy aroma. The aroma release of methylketones, esters, and lactones from the W/O-emulsion fat blends increased with increasing carbon chain length of the volatile molecules. The intensity of aroma perception in a W/O-emulsion fat blend depended on the melting point of the fatty acids (oleic, palmitic, stearic, and behenic) of the monoglyceride used as an emulsifier. Thus, aroma release from a W/O-emulsion semisolid fat blend was influenced by interactions between aroma volatiles and the dispersed aqueous droplets and by their viscoelastic properties.

Surface only modification of bacterial cellulose nanofibres with organic acids

Bacterial cellulose (BC) nanofibres were modified only on their surface using an esterification reaction with acetic acid, hexanoic acid or dodecanoic acid. This reaction rendered the extremely hydrophilic surfaces of BC nanofibres hydrophobic. The hydrophobicity of BC increased with increasing carbon chain length of the organic acids used for the esterification reaction. Streaming (zeta-) potential measurements showed a slight shift in the isoelectric point and a decrease in ζplateau was also observed after the esterification reactions. This was attributed to the loss of acidic functional groups and increase in hydrophobicity due to esterification of BC with organic acids. A method based on hydrogen/deuterium exchange was developed to evaluate the availability of surface hydroxyl groups of neat and modified BC. The thermal degradation temperature of modified BC sheets decreased with increasing carbon chain length of the organic acids used. This is thought to be a direct result of the esterification reaction, which significantly reduces the packing efficiency of the nanofibres because of a reduction in the number of effective hydrogen bonds between them.

Engineering the nucleotide coenzyme specificity and sulfhydryl redox sensitivity of two stress-responsive aldehyde dehydrogenase isoenzymes of Arabidopsis thaliana

Lipid peroxidation is one of the consequences of environmental stress in plants and leads to the accumulation of highly toxic, reactive aldehydes. One of the processes to detoxify these aldehydes is their oxidation into carboxylic acids catalyzed by NAD(P)+-dependent ALDHs (aldehyde dehydrogenases). We investigated kinetic parameters of two Arabidopsis thaliana family 3 ALDHs, the cytosolic ALDH3H1 and the chloroplastic isoform ALDH3I1. Both enzymes had similar substrate specificity and oxidized saturated aliphatic aldehydes. Catalytic efficiencies improved with the increase of carbon chain length. Both enzymes were also able to oxidize α,β-unsaturated aldehydes, but not aromatic aldehydes. Activity of ALDH3H1 was NAD+-dependent, whereas ALDH3I1 was able to use NAD+ and NADP+. An unusual isoleucine residue within the coenzyme-binding cleft was responsible for the NAD+-dependence of ALDH3H1. Engineering the coenzyme-binding environment of ALDH3I1 elucidated the influence of the surrounding amino acids. Enzyme activities of both ALDHs were redox-sensitive. Inhibition was correlated with oxidation of both catalytic and non-catalytic cysteine residues in addition to homodimer formation. Dimerization and inactivation could be reversed by reducing agents. Mutant analysis showed that cysteine residues mediating homodimerization are located in the N-terminal region. Modelling of the protein structures revealed that the redox-sensitive cysteine residues are located at the surfaces of the subunits.

Density and Excess Molar Volume of the Protic Ionic Liquid Bis(2-hydroxyethyl)ammonium Acetate with Alcohols

Densities were determined for binary mixtures containing the protic ionic liquid bis(2-hydroxyethyl)ammonium acetate [BHEAA] and an alcohol (methanol, ethanol, and 1-propanol) at four different temperatures (293.15, 303.15, 313.15, and 323.15) K and ambient pressure. Coefficients of thermal expansion and excess molar volumes were calculated from the experimental densities. The excess molar volumes were fitted using the Redlich-Kister polynomial equation. Negative deviations from ideal behavior of the excess molar volume were observed for all systems investigated in this study. The results were interpreted in terms of ion-dipole interactions and structural factors of the ionic liquid and alcohol. It was observed that an increase of the alcohol carbon chain length led to lower interactions on mixing.

The Crystal Structure of Human Transketolase and New Insights into Its Mode of Action

The crystal structure of human transketolase (TKT), a thiamine diphosphate (ThDP) and Ca(2+)-dependent enzyme that catalyzes the interketol transfer between ketoses and aldoses as part of the pentose phosphate pathway, has been determined to 1.75 Å resolution. The recombinantly produced protein crystallized in space group C2 containing one monomer in the asymmetric unit. Two monomers form the homodimeric biological assembly with two identical active sites at the dimer interface. Although the protomer exhibits the typical three (α/β)-domain structure and topology reported for TKTs from other species, structural differences are observed for several loop regions and the linker that connects the PP and Pyr domain. The cofactor and substrate binding sites of human TKT bear high resemblance to those of other TKTs but also feature unique properties, including two lysines and a serine that interact with the β-phosphate of ThDP. Furthermore, Gln(189) spans over the thiazolium moiety of ThDP and replaces an isoleucine found in most non-mammalian TKTs. The side chain of Gln(428) forms a hydrogen bond with the 4'-amino group of ThDP and replaces a histidine that is invariant in all non-mammalian TKTs. All other amino acids involved in substrate binding and catalysis are strictly conserved. Besides a steady-state kinetic analysis, microscopic equilibria of the donor half-reaction were characterized by an NMR-based intermediate analysis. These studies reveal that formation of the central 1,2-dihydroxyethyl-ThDP carbanion-enamine intermediate is thermodynamically favored with increasing carbon chain length of the donor ketose substrate. Based on the structure of human transketolase and sequence alignments, putative functional properties of the related transketolase-like proteins TKTL1 and -2 are discussed in light of recent findings suggesting that TKTL1 plays a role in cancerogenesis.

Enzymatic epoxidation of soybean oil methyl esters in the presence of free fatty acids

AbstractEpoxides of soybean oil methyl esters (SMEs) are biodegradable, non‐toxic, and renewable epoxy plasticizers. The objective of the present work was to investigate the effects of free fatty acids on the enzymatic epoxidation of SMEs. The results showed that the epoxidation of SMEs depended on the type of the added free fatty acid. For saturated (≤C18:0) and monounsaturated free fatty acids, the epoxy oxygen group content (EOC) of SMEs increased with increasing carbon chain length of free fatty acids; for branched‐chain unsaturated free fatty acids, the EOC of SMEs decreased in the presence of hydroxyl group (OH) and hydroperoxide (OOH) of free fatty acids; the EOC of SMEs decreased with increasing number of double bonds of free fatty acids. The maximum EOC and the initial epoxidization rate (V0) linearly decreased with increasing peroxide value of SMEs. The highest EOC (6.87 ± 0.3%) of SMEs was obtained using behenic acid as reaction material, which was similar with that of stearic acid (EOC 6.75 ± 0.2%).

ELISA assays and alcohol: increasing carbon chain length can interfere with detection of cytokines

Enzyme-linked immunosorbent assays (ELISAs) are frequently used in studies on cytokine production in response to treatment of cell cultures or laboratory animals. When an ELISA assay is performed on cell culture supernatants, samples often contain the treatment agents. The purpose of the present study was to determine if some of the agents evaluated might inhibit cytokine detection by interfering with the ELISA, leaving the question of whether cytokine production was inhibited unanswered. Mouse and human cytokine ELISA kits from BD Biosciences were used according to the manufacturer’s instructions. Cytokine proteins were subjected to one to five carbon alcohols at 86.8 mM (methanol, ethanol, 1-propanol, 2-propanol, n-butanol, and n-pentanol). After treating cell cultures with alcohols of different carbon chain lengths, we found that some of the alcohols interfered with measurement of some cytokines by ELISA, thus making their effects on cytokine production by cells in culture unclear. Increasing carbon chain length of straight chain alcohols positively correlated with their ability to inhibit detection of tumor necrosis factor alpha (TNF-α) and interleukin 10 (IL-10), but not with the detection of interleukin 6 (IL-6), interleukin 8, (IL-8), and interleukin 12 (IL-12). To avoid misinterpretation of treatment effects, ELISA assays should be tested with the reference protein and the treatment agent first, before testing biological samples. These results along with other recent results we obtained using circular dichroism indicate that alcohols with two or more carbons can directly alter protein conformation enough to disrupt binding in an ELISA (shown in the present study) or to inhibit ligand-induced conformational changes (results not shown). Such direct effects have not been given enough consideration as a mechanism of ethanol action in the immune system.

Exploration of Organic Acid Chain Length on Water-Soluble Silicon Quantum Dot Surfaces

Surface functionalization of silicon quantum dots influences oxidation of the silicon core while affording control of physical properties and maintaining optical stability. An effective method for surface modification is photochemical hydrosilylation in which the hydride-terminated Si surface is reacted with an unsaturated C-C bond resulting in a covalent Si-C bond at the surface. The physical properties (e.g., reactivity and solvent compatibility) of the nanocrystals are thus dictated by those of the pendant functional group. Water-soluble nanoparticles can be produced by extending polar functional groups, such as carboxylic acids, from the surface. Previous literature reports have shown acrylic acid to be an attractive starting material for creating water-soluble Si nanocrystals. To date, a detailed study of the effects of differing surface groups (i.e., carboxylic acids of varying carbon chain lengths) has not been offered. Here, we investigate the effects of carboxylic acid surface moieties with increasing carbon chain length on various silicon nanocrystal properties. Oxidative and optical stability was improved by increasing the length of the carbon spacer between the silicon surface and the polar carboxylic acid group. As well, increased chain length was found to enhance nanocrystal dispersibility in polar solvents. Of important note, however, the use of acrylic acid as a precursor led to poly(acrylic acid) formation under the reaction conditions studied, leading to anomalous behavior compared to precursors with longer carbon chains.

3-Aryl-2-{4-[4-(2,4-dioxothiazolidin-5-ylmethyl)phenoxy]-phenyl}-acrylic acid alkyl ester: synthesis and antihyperglycemic evaluation

A number of 2,4-thiazolidinedione derivatives of aryl-substituted cinnamic acid were synthesized and studied for their antihyperglycemic activity in neonatal streptozotocin-induced diabetic Wister male rats. Substitution of the aryl ring resulted in higher activity. 3-(2,4-Dimethoxyphenyl)-2-{4-[4-(2,4-dioxothiazolidin-5-ylmethyl)phenoxy]-phenyl}-acrylic acid methyl ester (Thz7), was found to be most active compound in this series which showed that disubstitutions on aryl ring by electron releasing groups were found suitable for promising antihyperglycemic activity. Increase in the ester carbon chain length decreased the activity.

Synthesis and Spectral Characterization of EuPO4 and LaPO4:Eu Nanorods

Monoclinic monazite-type EuPO4 and LaPO4:Eu nanorods were synthesized by a microemulsion-assisted solvothermal method. Their morphologies, structures, and fluorescent properties were characterized by SEM, XRD, and photoluminescence (PL) modern analytic means, respectively. The aspect ratios of EuPO4 and LaPO4:Eu nanorods have a decreasing tendency with increasing carbon chain length of assisted surfactants. When the assisted surfactant was n-butyl alcohol, the EuPO4 exhibited nanorod morphology with diameters from 20 to 30 nm and lengths from 100 to 150 nm. When the assisted surfactant was n-pentanol, the EuPO4 nanorods had lengths between 200 and 300 nm and a diameter range similar to that of the n-butyl alcohol nanorods. When the assisted surfactant was n-hexanol and n-octyl alcohol, only elliptical EuPO4 products were obtained. The LaPO4:Eu nanorods synthesized in the presence of different assisted-surfactants exhibited elliptical morphologies with diameters of 40-60 nm and lengths of 70-110 nm. The LaPO4:Eu and EuPO4 nanorods showed a orange prominent emission peak from magnetic-dipole transition 5D0 --> F1 (593 nm) of Eu3+ ions whose sites in the EuPO4 and LaPO4:Eu nanorods have C1 symmetry. Compared with bulk LaPO4:Eu, the fine structure of the Eu-O charge transfer band has very small red shift resulting from the slight increase of the length of Eu-O bond due to nanoscale size effect.

Trophodynamics of Some PFCs and BFRs in a Western Canadian Arctic Marine Food Web

The trophodynamics of per- and polyfluorinated compounds and bromine-based flame retardants were examined in components of a marine food web from the western Canadian Arctic. The animals studied and their relative trophic status in the food web, established using stable isotopes of nitrogen (delta15N), were beluga (Delphinapterus leucas) > ringed seal (Phoca hispida) > Arctic cod (Boreogadus saida) > Pacific herring (Clupea pallasi) approximately equal to Arctic cisco (Coregonus autumnalis) > pelagic amphipod (Themisto libellula) > Arctic copepod (Calanus hyperboreus). For the brominated diphenyl ethers, the lipid adjusted concentrations of the seven congeners analyzed (Sigma7BDEs: -47, -85, -99, -100, -153, -154, and -209) ranged from 205.4 +/- 52.7 ng/g in Arctic cod to 2.6 +/- 0.4 ng/g in ringed seals. Mean Sigma7BDEs concentrations in Arctic copepods, 16.4 ng/g (n = 2, composite sample), were greater than those in the top trophic level (TL) marine mammals and suggests that (i) Arctic copepods are an important dietary component that delivers BDEs to the food web and (ii) because these compounds are bioaccumulative, metabolism and depletion of BDE congeners in top TL mammals is an important biological process. There were differences in the concentration profiles of the isomers of hexabromocyclododecane (HBCD) in the food web. The most notable difference was observed for beluga, where the alpha-isomer was enriched (accounting for approximately 90% of the SigmaHBCD body burden), relative to its primary prey species, Arctic cod, where the alpha-isomer accounted for only 20% of the SigmaHBCD body burden (beta: 4% and gamma: 78%). For the C8-C11 perfluorinated carboxylic acids, the trophic magnification factors (TMFs) were all greater than unity and increased with increasing carbon chain length. PFOS and its neutral precursor, PFOSA, also had TMF values greater than one. There were also pronounced differences in the PFOSA to PFOS ratio in ringed seal (0.04) and in beluga (1.4) and suggests that, in part, there are differences in the efficacy of biotransforming PFOSA by whale and seal top predators that both preferentially feed on Arctic cod.