Determination of TBA number by high performance liquid chromatography

A high performance liquid chromatographic (HPLC) method for the quantitation of malonaldehyde in aqueous distillates was developed. Compared with the standard TBA test, the HPLC method was faster, and less affected by side feactions. A total of 5 min was necessary to assay each distillate and only malonaldehyde was detected. The standard curves were reproducible and standards were stable for up to 6 days. The HPLC method could detect malonaldehyde levels ranging from 1×10⁻¹¹ to 4×10⁻¹¹ mol/10μL and either peak height or peak area could be used to quantitate the malonaldehyde concentration. The coefficient of determination between absorbance values determined by the TBA test and peak heights determined by HPLC was 0.946. Twenty-one freeze-dried chicken samples with TBA numbers ranging from 3.93 to 16.6 were used for this correlation.     

Determination of ethylene oxide oligomer distributions in alcohol ethoxylates by HPLC using a rotating disc-flame ionization detector

A high performance liquid chromatographic (HPLC) method has been developed for the quantitative determination of ethylene oxide (EO) oligomer distributions (% wt) in acetylated alcohol ethoxylates, R(OCH₂CH₂)_nOH, from n=0, 1 to n=30 using a rotating disc-flame ionization detector. Both single carbon number and mixed carbon number alcohol-based (NEODOL® ethoxylates) samples have been analyzed by gradient elution with 2 different solvent systems on a Waters μ-Porasil column. With both solvent systems, 95% hexane is the initial solvent but with one system, 100% acetone is the final solvent and with the other, 10% methanol/90% acetone is used. The latter solvent elutes the higher ethoxylates from n=21 to n=30 quantitatively from the μ-Porasil column which the 100% acetone solvent fails to do. The 100% acetone solvent separates n=2 and n=3 from n=0,1 which the methanol-containing solvent does not do. Response factors for n=3 and n=8 have been experimentally determined and the response factors for the other EO units have been calculated from these 2 results. The corrected EO oligomer distributions for both NEODOL® 25-9 and NEODOL® 23-6.5 determined by HPLC are in good agreement with those determined earlier by circular thin layer chromatography (up to n=16 can be determined by this method). The average EO numbers determined by the HPLC method and by a wet chemical (phthalic anhydride) method are in excellent agreement for the above 2 samples and a sample of NEODOL® 23-7.5. The results are discussed in terms of Snyder’s theory for gradient elution in HPLC using the gradient steepness parameter.     

Confectionery fat analysis with high performance liquid chromatography

Natural triglyceride mixtures have been analyzed by a variety of techniques. Earlier methods, such as crystallization, were unsuitable because they were very time-consuming, required large amounts of material and were not reproducible. Later advances in chromatography gave successful separations of triglycerides but required a combination of techniques to give suitable separations. High performance liquid chromatography (HPLC) with very efficient columns has been successfully applied to triglyceride separations on a routine basis. In the present work, triglycerides of cocoa butter as well as several replacement fats were separated by HPLC. The system consisted of a highly efficient column packed with octadecylbonded spherical silica (5 μ) and a mobile phase composed of acetone and acetonitrile. Peaks corresponding to eluted components were collected and their composition determined by gas chromatography (GC) of the corresponding methyl esters to allow unambiguous assignment of triglyceride structure to the components. A profile of the triglycerides present in such fats can be obtained within 30 min.     

Enzymatic acylation of ether and ester lysophospholipids in rat liver microsomes

The acylation of lysophospholipids by rat liver acyltransferases was studied. A comparison between ester and ether lysophospholipids as substrates revealed large differences in substrate properties. For instance, oleic acid from oleoyl-CoA and arachidonic acid from arachidonoyl-CoA were not incorporated into 1-O-octadecyl-sn-glycero-3-phosphocholine under experimental conditions that allowed an optimal transfer of oleic acid and arachidonic acid to 1-O-palmitoyl-sn-glycero-3-phosphocholine. However, we observed an acyl-CoA-independent transfer of arachidonic acid from 1-O-stearoyl-2-O-arachidonoyl-sn-glycero-3-phosphoinositol to 1-O-octadecyl-sn-glycero-3-phosphocholine.     

Analysis of milkfat by HPLC

A routine method for HPLC analysis of milkfat has been developed, which takes into account the specific phenomena of this complex and far-ranging system of triglycerides. The usual amount of injection of 1 mg has been reduced to 30 or 10 μg of fat. By this the composition of the mobile phase (acetone:acetonitrile, 35/65) and the temperature of the column (Nucleosil C18-5 μ, 15 cm + Microspher C18-3μ, 10 cm, in series, T=30–35 C) could be adjusted to a relatively high selectivity without inducing the high-melting fat components to crystallize on the column. A further advantage resulting from this consisted in permitting the eluent to be recycled over long periods of time. The extremely low amounts of samples necessitated a highly sensitive detection (Δn=5 × 10⁻⁷ RI units full scale deflection) which could be realized by an interferential refractometer in connection with a thermostat to keep up a stable temperature of the whole HPLC system (ΔT<0,005 K). By this it was possible to separate milkfat into 45 to 50 different types of triglycerides. By comparing soft and hard milkfats and fractions of milkfats, every fourth peak, starting with C 42, could be attributed to saturated triglycerides; apart from this, easily recognizable qualitative features appearing in the chromatograms permitted conclusions about the feeding regimen and energy supply of the cattle. Furthermore, due to the high stability of separating conditions achieved and due to computer software developed for this purpose it was possible to obtain and compare a large number of chromatograms under the same conditions.     

Determination of surfactant mixtures in shampoos and detergents by HPLC

A technique for separating 4 nonionic, 7 anionic and 4 amphoteric surfactants with n-dodecyl groups was studied by high performance liquid chromatography (HPLC) and applied to the determination of these surfactants in commercial shampoos and household detergents. Conditions used for the separation were: column packing and size, TSK-LS 410 (5μ) and 6 mm i.d. × 500 mm (2 connected, 250 mm columns); mobile phase, water/methanol (25/75, v/v) containing 0.25 M sodium perchlorate adjusted to pH 2.5 with phosphoric acid; column temp., 50 C; detector, RI. Surfactants in shampoos and detergents were clearly distinguished from each other and determined without column chromatographic pretreatment, e.g., ion-exchange chromatography.     

Identification and quantification of cholesterol oxides in grated cheese and bleached butteroil

Butteroil samples bleached with benzoyl peroxide (BP) and 17 commercial cheeses were screened for oxidized sterols by thin layer chromatography (TLC). Ungrated cheeses made from bleached milk and freshly bleached butteroil contained no detectable oxidized sterols. Oxidized sterols were detected in stored, bleached butteroils and in grated cheeses. Four major oxidation products were the isomeric 5,6-epoxycholesterols and the epimeric 7-hydroxycholesterols identified by TLC, high performance liquid chromatography (HPLC) and mass spectrometry (MS). Additional sterol oxides (tentatively identified and not quantified) present in these samples included low levels of 7-ketocholesterol and cholesta-3,5-dien-7-one. The epimeric 7-hydroxycholesterols were detected in bleached butteroils stored in air (BP-A) and nitrogen (BP-N) for 22 days at 15 C. Butteroil, after 90 days of storage at 15 C, had 30 (BP-N) and 60 (BP-A) μg total oxides/g of bleached oil and, after 1-year at −20 C, had 70 (BP-N) and 180 (BP-A) μg/g butteroil. A grated, unbleached cheese packaged in clear glass contained the most oxidized sterols (44 μg/g). Sterol oxides were not detected in bleached cream using a simulated industrial process.     

Rapid analysis of dimer acid by HPLC/FID

A method was developed for the rapid analysis of polymerized fatty acids (dimer acid) using normal phase HPLC with a flame ionization detector (FID). The use of analytical scale HPLC with the FID is a significant limprovement over existing methodology for dimer analysis. The HPLC analysis takes only 25 min per sample, with no derivatization required. The FID response is linear for dimer samples from 10% to 90% monomer content. Absolute measurement precision is typically less than 0.5 area percent. Recovery of synthetic dimer blends averaged 102%. Results for the analysis of commercial dimer acid are comparable to those obtained using an HPLC/gravimetric method. The HPLC/FID method is applicable to the analysis of crude dimer as well as the finished dimer product.     

Lipids in chinese medicine. Characterization of allcis 5,11,14,17-eicosatetraenoic acid inBiota orientalis seed oil and a study of oxo/furanoid esters derived fromBiota oil

The fatty acid composition ofBiota orientalis seed oil consists of palmitic (5.1%), stearic (3.4%), oleic (15.3%), linoleic (25.6%), linolenic (34.7%), C20:3(11c,14c,17c) 4.9%, and C20:4(5c,11c,14c,17c) 10.5%. The unsaturated fatty esters derived fromBiota oil were epoxidized and subsequently treated with NaI-PrI-DMSO. Chromatographic separation of the complex product mixture revealed the presence of C18-oxo, C18-furanoid, and C18-and C20-oxo-furanoid esters. Epoxidation of a pure sample of C20:4(5c,11c,14c,17c) followed by NaI-PrI-DMSO treatment gave a mixture of C20-dioxo-furanoid esters. The positions of the oxo and furanoid groups in the various derivatives were determined by GC/MS analysis.     

The analysis of glycerol by gas chromatography

Commencai glycerol and its organic impurities can be measured accurately by a single gas Chromatographic GC analysis utilizing Tenax-GC® and flame detection.     

Synthesis of EPDM-g-MAN by suspension graft copolymerization and its toughening effect on SAN resin

Suspension graft copolymerization of methyl methacrylate and acrylonitrile onto ethylene–propylene–diene terpolymer (EPDM) was carried out under different reaction conditions. A series of graft products of EPDM-graft-methyl methacrylate and acrylonitrile (EPDM-g-MAN), characterized by Fourier-transform infrared spectroscopy, was blended separately with styrene–acrylonitrile (SAN) resin to investigate their toughening effect on SAN matrix. The relationship between the polarity of EPDM-g-MAN and toughness of EPDM-g-MAN/SAN resin blends (AEMS) was evaluated. The compatibility and morphologies of AEMS were probed by dynamic mechanical analysis, transmission electron microscopy, and scanning electron microscopy to determine the toughing mechanism of the blends. Thermogravimetry results showed that the thermal stability of AEMS was enhanced with the incorporation of EPDM-g-MAN graft copolymer.     

Unsaturated fatty acids in the postnatally developing rat lung

Fatty acid desaturase activity specific for the C-9 position is present in lung microsomes prepared from rats of all ages. This activity is significantly lower in neonatal rat lung compared with adult lung. A rapid increase in C-9 fatty acid desaturase activity seen at the approximate time of weaning may be related to a decrease in the polyunsaturated fatty acid (PUFA) content of the diet as the rat begins to consume laboratory chow instead of mother's milk. The 900×g supernatant fraction of rat lung parenchymal cell homogenates is capable of incorporating linoleate, linolenate, and arachidonate into both triacylglycerols and phospholipids. Lung tissue from rats less than 20 days old incorporates these PUFA into phospholipids at a greater rate than lung, tissue from adult rats. The incorporation of these PUFA into phospholipids in neonatal lung tissue occured at a greater rate than their incorporation into triacylglycerols. In contrast, lung tissue from adult rats incorporated PUFA into triacylglycerols at a greater rate than into phospholipids. These data show that PUFA, known to be elevated in neonatal rat lungs, are used primarily for phospholipid biosynthesis in neonatal lung tissue whereas in adult lung tissue they are preferentially esterified to glycerol.     

Systematic protocol for the accumulation of fatty acid data from multiple tissue samples: Tissue handling,lipid extraction and class separation,and capillary gas chromatographic analysis

A systematic procedure was developed for detailed fatty acid profiling of both neutral and polar lipid fractions isolated from hundreds of related bovine muscle and adipose tissue samples. A regimen was established for a nonbiased handling of tissue samples, which included their handling in a predetermined random order. Lipid class separation was accomplished concomitantly during the extraction of the tissues by a selective dry column method, which allowed a detailed analysis of minor but important polyunsaturated fatty acids associated with the polar fraction. Neutral lipids were derivatized to fatty acid methyl esters (FAME) by a literature procedure. However, to protect against lysis of plasmalogens in the polar fraction, a modified nonacidic esterification procedure was developed. FAME profiles were obtained on a program-mable high resolution capillary gas chromatograph (GC). Run programs for unattended GC operation and data storage are described. By this overall procedure, the quantitation and peak identification were obtained for major and minor fatty acid constituents from bovine tissue in a manner that prepares for valid statistical interpretation of the resulting data.     

Automated AOM test for fat stability

A home-built version of the automated AOM test was used with Canola, corn, sunflower, olive and Crisco? oils, shortening and lard. The endpoint was found by measuring the conductivity of a solution of the exit gas from the reaction tube. Coefficients of variability of the samples ranged from 1.1% to 8.3%. The endpoint of the test was ca. 100 PV for Canola oil, ca. 200 PV for corn oil and 35 PV for lard. The aqueous solutions of the volatiles of three oils were used to determine the TBA value. Canola, sunflower and olive oil had TBA values ranging from 6–60 μg malonaldehyde/g at the end point. No apparent relationship was found between the TBA values of the volatiles’ solutions and the PV’s of the oils. Presented at the 73rd AOCS Annual Meeting, Toronto, 1982.     

Determination of ascorbyl palmitate by high performance liquid chromatography

An HPLC method for the determination of ascorbyl palmitate in vegetable oil and lard has been developed. Chromatographic conditions consist of a diamine column, a mobile phase of 70:30 (v/v) methanol:0.02M monobasic potassium phosphate buffer, pH 3.5, and UV detection. Samples were extracted with methanol. An overall average recovery value of 96.7% was obtained for ascorbyl palmitate in five representative vegetable oils and lard.     

Complete mineralization of the antibiotic amoxicillin by electro-Fenton with a BDD anode

On April 30, 2014, the World Health Organization’s first global report on the presence of antibiotics in waters focused on their negative consequences, which may include the growth of microorganisms with antimicrobial resistance. The β-lactam antibiotic amoxicillin (AMX) is widely used in human and veterinary medicine, and it has been recently detected in sewage treatment plants and effluents. In this paper, the degradation of acidic aqueous solutions of AMX by electro-Fenton process has been studied at constant current. Experiments have been performed in an undivided cell equipped with a carbon-felt cathode and a Pt or boron-doped diamond (BDD) anode. In such systems, the organic molecules are mainly oxidized by hydroxyl radical (^?OH) simultaneously formed on the anode surface from water oxidation as well as in the bulk from Fenton’s reaction between Fe²⁺ catalyst and electrogenerated H₂O₂. The decay and mineralization of AMX was monitored by means of high performance liquid chromatography (HPLC) and TOC measurements. The evolution of the concentration of the final aliphatic carboxylic acids and inorganic ions like ammonium, nitrate and sulfate was assessed by HPLC and ion chromatography, respectively. The effect of the anode material, initial AMX concentration and current density was thoroughly studied. The AMX decay always followed a pseudo-first-order kinetics using either Pt or BDD, and the apparent rate constant increased with applied current. A quicker mineralization was reached with BDD because of the larger production of active ^?OH. The absolute rate constant between hydroxyl radical and AMX determined by the competition kinetics method using p-hydroxybenzoic acid as the reference compound was found to be (2.02 ± 0.01) × 10⁹ M^?1 s^?1.     

Carotenoids and tocols of corn grain determined by HPLC

A high performance liquid chromatographic (HPLC) procedure has been developed that permits determinationof carotenoids and tocols in the same sample preparation of corn grain. For 15 inbreds, the total carotenoids ranged from 16 to 77 μg/g dry wt and the total tocols from 30 to 128 μg/g dry wt. For four inbreds, total carotenoids were concentrated in the horny endosperm (83±2%) and total tocols in the germ (77±6%). After six months storage at room temperature, the mean loss of total carotenoids for four inbreds was 42±4%, while the tocols had a mean loss of 5%. Presented at the AOCS meeting in Honolulu, HI in May 1986.     

Selected factors influencing neurohormonal regulation of sex pheromone production inHeliothis species

Sex pheromone production and release in females ofHeliothis species exhibit a diel periodicity. Phermone production is controlled by a hormone, the pheromone biosynthesis activating neuropeptide (PBAN). Release of PBAN to activate pheromone production follows a circadian rhythm. InH. zea females, mating terminates pheromone production. An unidentified hemolymph-borne factor is transferred from the male to the female during mating. It is speculated that this factor interacts with the release mechanism of PBAN to prevent further production of the pheromone following mating. Wild females ofH. phloxiphaga (reared from larvae collected in the field) did not produce or release the sex pheromone unless kept in association with the host plant. Pheromone production could be induced in these females by the injection of PBAN. It is suggested that a signal from the host plant is essential to trigger the release of PBAN to induce pheromone production.     

Rheological behavior of a LDPE/PS/SBS blending melt

The dynamic rheological behaviors are measured by small amplitude oscillatory shear on a rotational rheometer for a low-density polyethylene (LDPE)/polystyrene (PS)/styrene–butadiene–styrene (SBS) block copolymer blend with the tool of cole–cole plot. The morphology of the blend is measured by scanning electron microscope (SEM) micrograph, the storage moduli–angular frequency (G′–ω) data are fit by the Palierne model, and the relaxation time spectrum is investigated. The storage modulus and loss modulus of the LDPE/PS/SBS blend at low frequency increase when the weight ratio LDPE/PS increases from 10/90, reaches a maximum of 30/70, and drops thereafter. The cole–cole plots of some blends (10/90/3, 70/30/3, 90/10/3 and 100/0/3) have only one main arc due to compatibilizing effect of the SBS, and those of other blends (0/100/3, 30/70/3 and 50/50/3) have a second arc or a long tail besides the main arc probably due to phase separation. The SEM micrographs of the LDPE/PS/SBS = 10/90/3, 30/70/3, 50/50/3 show sea-island, semi-co-continuous and co-continuous structure, respectively. G′–ω curve of two LDPE/PS/SBS = 30/70/3 and 50/50/3 blends shows a power law, and the power index is much lower than one (0.748 and 0.817), respectively, showing a co-continuous morphology also verified by the SEM micrographs. The experimental data of G′–ω curve of the LDPE/PS/SBS blends are fit by Palierne model, the deviation between the fit line and the experimental data increases gradually as the LDPE/PS weight ratio decreases from 90/10 to 10/90. For the LDPE/PS/SBS blends, the weighted relaxation spectra τH (τ)–τ show a main as well as a second arc or tail; the former corresponding to the relaxation of PS phase and the latter corresponding to that of LDPE phase. Due to the compatibilizing effect of SBS the relaxation time and spectrum strength of LDPE/PS = 50/50 (wt) blends are both increased.     

Oil content and fatty acid composition of peanuts imported into japan

The oil content and fatty acid composition of Virginia, Runner, and Spanish market types of peanuts imported into Japan were determined. The significant differences among the countries of production were shown in stearic, eicosenoic and lignoceric acid contents of Virginia market type and oil content and palmitic, stearic, oleic, linoleic, eicosenoic, behenic and lignoceric acid contents of Spanish market type. The Spanish market type, as compared with the Virginia market type, was significantly higher in palmitic, stearic, linoleic, arachidic and behenic acid contents and lower in oleic, eicosenoic and lignoceric acid contents on the gross samples.