Quantitative determination of butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone in oils, foods, and biological fluids by high-performance liquid chromatography with fluorometric detection

Concentrations of synthetic antioxidants butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone were quantified using a high-performance liquid chromatograph with spectrofluorometric detector. The antioxidants were separated and eluted on a reversed-phase column by gradient of a mixture of H2O/acetonitrile/acetic acid (66.5: 28.5:5, by vol) and a mixture of acetonitrile/acetic acid (95:5, vol/vol). The eluants were monitored at emission and excitation wavelengths of 310 and 280 nm, respectively. Calibration curves obtained using peak areas against concentration showed high coefficients of multiple determination (R2 > 0.99) for all antioxidants. Known concentrations of added antioxidant standards were recoverable within 98-99% from oils and over 93% from mouse blood. This method requires minimum sample extraction and purification before analysis and provides a relatively high percentage recovery. The method has been applied successfully for the measurement of antioxidant concentrations in oils, dried foods, and biological fluids.     

If it is supposed to be specialization, make it true specialization

As indicated by an Fe(II)-induced liposome peroxidation bioassay, the EtOAc extract of tart cherries (Prunus cerasus) was found to have strong antioxidant activity. Purification of this extract afforded chlorogenic acid methyl ester (1) and three novel compounds, 2-hydroxy-3-(o-hydroxyphenyl) propanoic acid (2); 1-(3', 4'-dihydroxycinnamoyl)-cyclopenta-2,5-diol (3), and 1-(3', 4'-dihydroxycinnamoyl)-cyclopenta-2,3-diol (4), as determined by their spectral data. At a 20-microM concentration, the antioxidant activities of compounds 3 and 4 were comparable to the antioxidant activities of caffeic acid, whereas compound 1 showed activity similar to chlorogenic acid. Also, these compounds showed antioxidant activities similar to the commercial antioxidants tert-butylhydroquinone and butylated hydroxytoluene. However, compound 2 was not active when tested at a 100-microM concentration.     

矿石中SiO2、TiO2、P、Mn的联合测定

采用碱熔法处理样品,用同一母液对矿石产品中的SiO2、TiO2、P、Mn进行了联合测定。通过控制测定的酸度,各元素线性良好,测得SiO2、TiO2、P、Mn的相对标准偏差分别小于3．70％、4．00％、4．44％、1．79％。该方法用于不同含量标准物质的测定,精密度和准确度高,结果令人满意。     

Experimental studies on the mechanisms of tiaprofenic acid photosensitization

Red blood cell lysis and histidine degradation, photosensitized by tiaprofenic acid (TIA), were investigated. Photohaemolysis was markedly enhanced in oxygenated solutions, but was also intense in the presence of nitrogen. Photohaemolysis was inhibited by butylated hydroxyanisole and reduced glutathione, but was unaffected by sodium azide, superoxide dismutase and mannitol. The TIA-induced photo-oxidation of histidine was greatly enhanced in the presence of oxygen and almost completely inhibited in solutions bubbled with nitrogen. Sodium azide, butylated hydroxyanisole and reduced glutathione inhibited the photodegradation of histidine. Phototoxicity to histidine was unaffected by mannitol and superoxide dismutase. The overall results suggest that molecular mechanisms involving free radicals and singlet oxygen are responsible for TIA-photosensitized reactions. These two in vitro models (photohaemolysis and histidine degradation) represent different mechanisms of phototoxicity, but complement one another in the investigation of potential phototoxic substances.     

Autoxidation in milk rich in linoleic acid. II. Modification of the initiation system and control of oxidation

Factors contributing to the initiation of lipid oxidation in cow's and mare's milk containing high levels of polyunsaturated fatty acids were studied. Addition of H2O2 just after milking, in slight excess of the stoichiometric amounts required to destroy ascorbic acid, delayed the development of oxidized flavours in cow's milk high in linoleic acid. Hydrogen peroxide treatment followed by the addition of alpha-or gamma-tocopherols prevented lipid oxidation in cow's milk even when 0.1 mg Cu/l milk was added. When used separately in the presence of Cu these treatments were ineffective as was butylated hydroxyanisole treatment. The lipid and ascorbic acid in mare's milk were remarkably stable to oxidation. Addition of 0.05 or 0.1 mg Cu/l, ethylenediamine tetraacetic acid, neocuproine, or H2O2 had very little effect on the loss of ascorbic acid and lipid oxidation in mare's milk.     

Cytotoxic action of cis-unsaturated fatty acids on human cervical carcinoma (HeLa) cells in vitro

The effect of n-3 and n-6 fatty acids (FAs) on the growth of human cervical carcinoma (HeLa) cells was studied. Of all the FAs tested, docosahexaenoic acid (DHA, 22:6 n-3) and eicosapentaenoic acid (EPA, 20:5 n-3) were found to be the most potent in their cytotoxic action on HeLa cells and the potency of various fatty acids with regard to their cytotoxic action was as follows: DHA > EPA > dihomo-gamma-linolenic acid (DGLA) = gamma-linolenic acid (GLA) > linoleic acid (LA) > arachidonic acid (AA) > alpha-linolenic acid (ALA). The cycloxygenase inhibitor indomethacin, the lipoxygenase inhibitor nordihydroguaretic acid (NDGA), the antioxidants vitamin E, butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT), the superoxide anion quencher superoxide dismutase (SOD), the hydroxyl and hydrogen peroxide quenchers mannitol and catalase, respectively, and the calmodulin antagonists trifluoperazine (TFP) and chlorpromazine (CPZ) could all block the cytotoxic action of GLA, which was used as a representative cytotoxic FA, on HeLa cells. On the other hand, copper and iron salts and buthionine sulfoxamine, a glutathione (GSH) depletor, potentiated the cytotoxic action of suboptimal doses of GLA. GLA-induced radical generation and lipid peroxidation in HeLa cells could be blocked by indomethacin, NDGA and calmodulin antagonists. The cytotoxic action of cis-unsaturated fatty acids (c-UFAs) is not dependent on the alteration in the protein kinase C levels since no alteration in the diacylglycerol levels was observed. Hydroxy and hydroperoxy products of GLA were found to be toxic to HeLa cells, whereas prostaglandin (PG)E1, PGF2 alpha, and prostacyclin stimulated cell growth. From these results, it is evident that radicals are the modulators of the cytotoxic action of c-UFAs, that their formation is a calmodulin-dependent process, and that lipoxygenase products may mediate the tumoricidal action of FAs.     

Proteins and their amino acid compositions: uniqueness, variability, and applications

Amino acid compositions (AAC) of proteins were analyzed in terms of their uniqueness and variability. Using several measures of convergence between the AACs of randomly chosen proteins versus those stored in protein data banks, it was established that certain families of proteins have unique AACs despite the mutations of their sequences which were imposed in the process of evolution. AACs may be used to establish the identities of many proteins which were sorted through various chromatographic media prior to their fractionation on two-dimensional (2D) gels. Subfractionations of proteins markedly enhance the chances for proper identification of low-abundant proteins which rest inaccessible if the total protein extract of an organ is analyzed on 2D gels. Although the amino acid composition versus protein identity (AAC-PI) method allows identification with high confidence of unique proteins resolved on monodimensional SDS-PAGE (1D) gels and arrays of protein isoforms resolved on two-dimensional (2D) gels, selective immunoblotting is still a more robust method. Thus, in principle, the AAC-PI method may allow limiting the number of "unknown" spots on 2D gels which could be further investigated by microsequencing and/or mass spectroscopy. However, to resolve certain ambiguities inherently linked with protein identities derived only from their AACs, the AAC-PI method must be sometimes aided by microsequencing and immunoblotting, especially in the construction of high-resolution 2D maps of proteins. A suite of algorithms which form the AAC-PI method are described in detail.     

铁矿石中SiO_2,CaO,MgO,Al_2O_3的系统分析

以过氧化钠为熔剂 ,于铁坩埚内进行快速熔融试样 ,熔块以水浸取 ,硝酸溶解盐类 ,对铁矿石、球团矿、烧结矿中二氧化硅、氧化钙、氧化镁、三氧化二铝进行系统分析。与国家标准方法相比 ,本法具有操作简便 ,准确性好 ,速度快 ,成本低 ,测定范围宽等特点     

Butylated hydroxyanisole inhibits tumor necrosis factor-induced cytotoxicity and arachidonic acid release

The mechanisms by which the antioxidant butylated hydroxyanisole (BHA) inhibits recombinant tumor necrosis factor alpha (rTNF-alpha)-induced cytotoxicity have been studied in WEHI 164 clone 13 (WEHI) and L929 fibrosarcoma cells. When BHA was added simultaneously with rTNF-alpha, it completely inhibited rTNF-alpha cytotoxicity in the WEHI and L929 cells. BHA also inhibited the toxicity when added 2 h after rTNF-alpha in WEHI cells, suggesting that BHA inhibits some late intracellular event(s) in rTNF-alpha cytotoxicity. Pretreating WEHI cells with BHA for 4 h did not decrease the binding of rTNF-alpha to its receptors as measured using flow cytometry. BHA inhibited rTNF-alpha toxicity in the presence of actinomycin D and cycloheximide, indicating that neither mRNA nor protein synthesis is necessary for the BHA effect. The antioxidant butylated hydroxytoluene (BHT) and indomethacin did not inhibit the rTNF-alpha-induced cytotoxicity nor the rTNF-alpha-induced release of [3H]arachidonic acid. By comparison, BHA completely inhibited the rTNF-alpha-induced release of arachidonic acid, suggesting that BHA somehow inhibits rTNF-alpha-induced activation of phospholipase(s). In WEHI cells, rTNF-alpha increased the level of protein-associated thiobarbituric acid reactive substances (TBARS) dose-dependently. BHA, but not BHT, blocked rTNF-alpha-induced cytotoxicity and rTNF-alpha-induced accumulation of protein-associated TBARS, suggesting that rTNF-alpha cytotoxicity is correlated with protein-associated TBARS. In conclusion, the results suggest that BHA blocks some post receptor event in rTNF-alpha-induced cytotoxicity, and that activation of phospholipase(s) coupled with the enzymatic formation of specific oxidized lipids could be a pivotal event in rTNF-alpha-induced cytotoxicity.     

The determination of BHT in resmethrin by high-pressure liquid chromatography

A method was developed to determine the amount of butylated hydroxy toluene in resmethrin and resmethrin formulations by high-pressure liquid chromatography.     

Experimental benznidazole encephalopathy: II. Electroencephalographic and morphological alterations

Glycated hemoglobin can be degraded by proteolytic enzyme(s) in the erythrocyte. The enzyme(s) co-elutes with glycated hemoglobin when the latter is separated from erythrocyte lysates using the cation-exchanger Bio Rex-70. A further purification of the Bio Rex eluant on DEAE Sephadex A-50 separated the enzyme(s) from glycated hemoglobin. Studies with the Bio Rex eluant showed that degradation of glycated hemoglobin is maximum at 37 degrees C at pH 8.6. Proteolytic degradation is inhibited by 5 mM N-ethylmaleimide (NEM), 5 mM ethylenediamine tetraacetic acid (EDTA) and 0.6 mM n-p-tosyl-L-lysine choromethyl ketone (TLCK) (100-87 and 76% inhibition respectively). This study also examines the possibility that oxidative-damage to glycated hemoglobin increases its susceptibility to proteolytic degradation. When incubated with various anti-oxidants like DTPA, uric acid, mannitol and butylated hydroxy toluene (BHT), proteolytic degradation of glycated hemoglobin decreased by 66.1, 50.7 and 38% respectively.     

Determination of total fat in foods and feeds by the caviezel method, based on a gas chromatographic technique

This peer-verified method specifies a fast, easy, and reliable quantitative method to determine total fat in foods and feeds in compliance with the new definition of fat from the U.S. Food and Drug Administration. The method takes into consideration all fatty acids, from C4 to C24, and when fat is present at 0.3-100%. The validation study included 9 matrixes, with fat levels ranging from 1 to 79%. Sample and internal standard (IS; tridecanoic acid) are added to solvent (n-butyl alcohol). Fat is extracted and simultaneously saponified by potassium hydroxide. The fatty acid potassium salts are converted to fatty acids by adding an acidic aqueous salt solution, which produces a 2-phase system. The upper phase, containing the fatty acids and IS, is injected into the fat determination system. After gas chromatographic separation, the fat content is calculated from IS and fatty acid peak areas. The fat content is automatically converted to triglyceride content with a pre-determined factor. Ten replicates of 9 different food samples, which cover the whole range of different contents in fat, proteins, and carbohydrates, were analyzed by the submitting and the peer laboratories. Repeatability relative standard deviation (RSDr) values ranged from 0.47 to 4.62%. Reproducibility relative standard deviation (RSDR) values ranged from 0.85 to 9.52%. These estimates include between-run variability. The method shows good accuracy. Values for standard reference materials (SRMs) are in agreement with certified values. Regression analysis of the correlation between observed fat and certified value over all matrixes and fat levels indicated good precision and absence of method bias (5 SRMs; 1-30% fat; correlation coefficient, R2 = 99.98%).     

Recovery of uranium,vanadium, yttrium and rare earths from phosphoric acid by a precipitation method

Commercial procedures for recovery of uranium from phosphoric acid are all based on solvent extraction techniques. Recovery of uranium from phosphoric acid in combination with direct production of concentrated acid is not possible on a commercial scale using solvent extraction. When a dispersion agent such as acetone, and a precipitation reagent - NH₄F - are added, uranium can be precipitated from high concentration (52% P₂O₅), as well as low concentration phosphoric acid (～30% P₂O₅) with 0.6 kg acetone/kg P₂O₅ and 60 g NH₄F/kg P₂O₅. Variation of all parameters, such as uranium valence, phosphoric acid concentration, type and quantity of the dispersion and precipitation agents, has made it possible to develop on a laboratory scale a preferential mode of operation which appears to make uranium recovery from high concentration acid even simpler than recovery from acid of low concentration. This method also enables recovery of ?90% of the yttrium and ?80% of the rare earths contained in the phosphoric acid. To precipitate vanadium much more acetone must be used. The economic calculations presented here show that uranium recovery by the precipitation method is considerably less expensive than recovery by extraction or by other proposed routes: $60/lb at phosphoric acid capacity of 300 kt/a P₂O₅ with solvent extraction and $41/lb yellow cake with the new precipitation route and the same capacity. At present uranium prices ($28/lb yellow cake), the precipitation method does not make uranium recovery by precipitation an economic proposition in the case of plants of moderate phosphoric acid capacities (about 300 kt/a P₂O₅); however, in combination with recovery of yttrium and/or rare earths it appears to become economic - $28/lb yellow cake - at this moderate capacity.     

Pilocarpine hydrochloride in ophthalmic solutions: modification of a high-pressure liquid chromatographic determination and survey

Pilocarpine undergoes 2 important reactions in solutions, epimerization to isopilocarpine and hydrolysis to pilocarpic acid. There is no official USP limit for isopilocarpine or pilocarpic acid in pilocarpine hydrochloride ophthalmic solutions. An existing high-pressure liquid chromatographic (HPLC) method was modified by changing the buffer system to permit its use with constant-pressure as well as constant-volume instruments. The procedure separates all 3 components on a cation exchange resin; pilocarpine and isopilocarpine are determined directly and pilocarpic acid indirectly. Ophthalmic solutions and drug substances were obtained from substantially all the United States marketers of pilocarpine opthalmic solutions and were analyzed by the modified HPLC method. Results of the survey show that isopilocarpine is present to the extent of 0.4-3% and pilocarpic acid at levels of 0.6-7% of total alkaloid.     

A new conjugated linoleic acid isomer, 7 trans, 9 cis-octadecadienoic acid, in cow milk, cheese, beef and human milk and adipose tissue

The identity of a previously unrecognized conjugated linoleic acid (CLA) isomer, 7 trans, 9 cis-octadecadienoic acid (18:2) was confirmed in milk, cheese, beef, human milk, and human adipose tissue. The 7 trans, 9 cis-18:2 isomer was resolved chromatographically as the methyl ester by silver ion-high-performance liquid chromatography (Ag+-HPLC); it eluted after the major 9 cis, 11 trans-18:2 isomer (rumenic acid) in the natural products analyzed. In the biological matrices investigated by Ag+-HPLC, the 7 trans, 9 cis-18:2 peak was generally due to the most abundant minor CLA isomer, ranging in concentration from 3 to 16% of total CLA. By gas chromatography (GC) with long polar capillary columns, the methyl ester of 7 trans, 9 cis-18:2 was shown to elute near the leading edge of the major 9 cis, 11 trans-18:2 peak, while the 4,4-dimethyloxazoline (DMOX) derivative permitted partial resolution of these two CLA isomers. The DMOX derivative of this new CLA isomer was analyzed by gas chromatography-electron ionization mass spectrometry (GC-EIMS). The double bond positions were at delta7 and delta9 as indicated by the characteristic mass spectral fragment ions at m/z 168, 180, 194, and 206, and their allylic cleavages at m/z 154 and 234. The cis/trans double-bond configuration was established by GC-direct deposition-Fourier transform infrared as evidenced from the doublet at 988 and 949 cm(-1) and absorptions at 3020 and 3002 cm(-1). The 7 trans, 9 cis-18:2 configuration was established by GC-EIMS for the DMOX derivative of the natural products examined, and by comparison to a similar product obtained from treatment of a mixture of methyl 8-hydroxy- and 11-hydroxyoctadec-9 cis enoates with BF3 in methanol.     

电感耦合等离子体质谱法测定镍铬合金中砷硒锡锑铅铋

准确测定镍铬合金中砷、硒、锡、锑、铅和铋含量,对镍铬合金的生产、应用具有重要意义。考虑到被测元素砷和硒的易挥发性质,采用10 mL盐酸-1 mL硝酸溶解镍铬合金,选用⁷⁵As、⁷⁷Se、¹²⁰Sn、¹²¹Sb、²⁰⁸Pb和²⁰⁹Bi为测量同位素,采用铑内标校正砷、硒、锡、锑的测定;铼内标校正铅、铋的测定,建立了电感耦合等离子体质谱法(ICP-MS)测定镍铬合金中砷、硒、锡、锑、铅和铋含量的方法。实验表明,在200 ℃加热蒸发样品溶液中Cl^—,将盐酸介质转化为硝酸介质,可消除多原子离子⁴⁰Ar³⁵Cl⁺、⁴⁰Ar³⁷Cl⁺对⁷⁵As、⁷⁷Se的干扰。对测定介质进行了进一步优化,确定以2%(V/V)盐酸为介质测定锡、锑、铅、铋含量;以2%(V/V)硝酸-乙醇为介质测定砷、硒含量。在优化的实验条件下,在2.00~25.00 ng/mL范围内,被测元素与相应内标元素信号强度的比值与被测元素质量浓度呈良好的线性关系,相关系数大于0.999 5。各元素的检出限为0.012~0.21 ng/mL,定量限为0.04~0.70 ng/mL。采用实验方法测定镍铬合金中砷、硒、锡、锑、铅和铋含量,测定结果与原子荧光光谱法(AFS)基本一致,相对标准偏差(n=11)为5.4%～12%,加标回收率为96%～120%。     

Ascorbic acid inhibits lipid peroxidation but enhances DNA damage in rat liver nuclei incubated with iron ions

In this report we studied DNA damage and lipid peroxidation in rat liver nuclei incubated with iron ions for up to 2 hrs in order to examine whether nuclear DNA damage was dependent on membrane lipid peroxidation. Lipid peroxidation was measured as thiobarbituric acid-reactive substances (TBARS) and DNA damage was measured as 8-OH-deoxyguanosine (8-OH-dG). We showed that Fe(II) induced nuclear lipid peroxidation dose-dependently but only the highest concentration (1.0 mM) used induced appreciable 8-OH-dG. Fe(III) up to 1 mM induced minimal lipid peroxidation and negligible amounts of 8-OH-dG. Ascorbic acid enhanced Fe(II)-induced lipid peroxidation at a ratio to Fe(II) of 1:1 but strongly inhibited peroxidation at ratios of 2.5:1 and 5:1. By contrast, ascorbate markedly enhanced DNA damage at all ratios tested and in a concentration-dependent manner. The nuclear DNA damage induced by 1 mM FeSO4/5 mM ascorbic acid was largely inhibited by iron chelators and by dimethylsulphoxide and mannitol, indicating the involvement of OH. Hydrogen peroxide and superoxide anions were also involved, as DNA damage was partially inhibited by catalase and, to a lesser extent, by superoxide dismutase. The chain-breaking antioxidants butylated hydroxytoluene and diphenylamine (an alkoxyl radical scavenger) did not inhibit DNA damage. Hence, this study demonstrated that ascorbic acid enhanced Fe(II)-induced DNA base modification which was not dependent on lipid peroxidation in rat liver nuclei.     

Quantitative determination of endogenous retinoids in mouse embryos by high-performance liquid chromatography with on-line solid-phase extraction, column switching and electrochemical detection

An isocratic high-performance liquid chromatographic method for the determination of 9-cis-retinoic acid, 13-cis-retinoic acid, all-trans-retinoic acid and all-trans-retinol in mouse embryos using on-line solid-phase extraction and column switching in combination with electrochemical detection has been developed. The method was validated using retinoids in albumin solutions and 13-cis-acitretin was used as internal standard. About 370 microliters of albumin solution was injected on a 10 x 2.1-mm I.D. pre-column packed with Bondapak C18, 37-53-micron particles. The proteins were washed to waste within 5 min using as mobile phase, a 1:3 dilution of mobile phase 2, which consisted of acetonitrile-methanol-2% ammonium acetate-glacial acetic acid (79:2:16:3, v/v). Components retained on the pre-column were back-flushed to and separated on the 250 x 4.6-mm I.D. Suplex pKb-100 analytical column using mobile phase 2. The retinoids were detected electrochemically at +750 mV using a coulometric electrochemical detector. The total analysis time was about 20 min. Recoveries were in the range of 86-103%. The mass limits of detection were about 10 pg and 25 pg for the retinoic acids and all-trans-retinol, respectively. The intra-assay precision, reported as relative standard deviation, was in general better than 4% (n = 6) for the four retinoids. Inter-assay precision was in the range 3-4% (n = 10). The method was applied for determination of endogenous retinoids in 9.5 day-old mouse embryos. A 340-microliter solution containing 100 microliters of embryo homogenate (1.64 embryos) was analyzed. The concentrations of all-trans-retinol and all-trans-retinoic acid were found to be 279 pg per embryo and 75.8 pg per embryo, respectively. The amount of 13-cis-retinoic acid and 9-cis-retinoic acid was below the detection limit.     

ICP-AES法测定铌铁中钛、钽、铜、铝、磷

研究了用ICP-AES法同时测定铌铁中钛、钽、铜、铝、磷的分析方法。试料用硝酸、氢氟酸分解,硫酸冒烟,以酒石酸溶液浸取并络合铌、钽等元素,试料溶液定容后,导入ICP发射光谱仪等离子体炬焰中进行测定。测得结果表明,该方法简便、快速、灵敏,相对标准偏差均小于5％,回收率在95％-105％之间。     

ICP-AES法测定铜合金中的Co、Cr、Zr元素含量

用ICP-AES同时测定铜合金中的Co、Cr、Zr元素含量,经试验比较,用盐酸、氢氟酸、硝酸、高氯酸溶解样品,确定了合适的谱线和背景校正方法,基本解决了基体干扰和待测元素间的干扰,适用于企业大量的检测要求。