Catalytic conversion of isopropyl alcohol on the heteropolic acid –titanium oxide system

A complex of modern physicochemical methods (X-ray phase analysis, low-temperature adsorption of nitrogen, scanning electron microscopy, element analysis)was used to studythe phase and texture properties of the phosphomolybdenum heteropoly acid–titanium oxide catalytic system. It was found that the optimal content of phosphomolybdenum heteropoly acid, which leads to an increase in the catalytic activity of titanium dioxide, is 7% wt.: the diisopropyl ether yield is higher,it reaches maximum values in a shorter period of time, and the samples are characterized by greater stability. It is shown that the textural characteristics of the specific surface area and dispersion are not the key factors responsible for the catalytic activity.It has been suggested that the activity of phosphomolybdenum heteropoly acid-containing samples is associated with the emergence of a new type of active centers that exhibit increased electron-donorproperties(terminal oxygen atoms of the outer frag-ments of octahedra М = О heteropolyacids). A drop in the catalytic activity of samples with a phosphomolyb-denum heteropoly acid content of more than 7% wt. associated with the formation of surface metaphosphoric acid and entails a decrease in active centers.

Multi-Class Procedure for Analysis of 50 Antibacterial Compounds in Eggshells Using Ultra-High-Performance Liquid Chromatography–Tandem Mass Spectrometry

In this work, for the first time, Ultra-High-Performance Liquid Chromatography–Tandem Mass Spectrometry (UHPLC–MS/MS) method was developed for qualitative and quantitative analysis of veterinary antibiotics (cephalosporins, diaminopyrimidines, fluoro(quinolones), lincosamides, macrolides, penicillins, pleuromutilins, sulfonamides, tetracyclines, and sulfones) in hen eggshells. The sample preparation method is based on a liquid–liquid extraction with a mixture of metaphosphoric acid, ascorbic acid, EDTA disodium salt dihydrate, and acetonitrile. The chromatographic separation was performed on Luna® Omega Polar C18 10 column in gradient elution mode and quantitated in an 8 min run. Validation such as linearity, selectivity, precision, recovery, matrix effect, limit of quantification (LOQ), and limit of detection (LOD) was found to be within the acceptance criteria of the validation guidelines of the Commission Decision 2002/657/EC and EUR 28099 EN. Average recoveries ranged from 81–120%. The calculated LOQ values ranged from 1 to 10 µg/kg, the LOD values ranged from 0.3 to 4.0 µg/kg, depending on analyte. The developed method has been successfully applied to the determination of antibacterial compounds in hen eggshell samples obtained from different sources. The results revealed that enrofloxacin, lincomycin, doxycycline, and oxytetracycline were detected in hen eggshell samples.

Determination of Ascorbic Acid, Total Ascorbic Acid, and Dehydroascorbic Acid in Bee Pollen Using Hydrophilic Interaction Liquid Chromatography-Ultraviolet Detection

Ascorbic acid (AA) is one of the essential nutrients in bee pollen, however, it is unstable and likely to be oxidized. Generally, the oxidation form (dehydroascorbic acid (DHA)) is considered to have equivalent biological activity as the reduction form. Thus, determination of the total content of AA and DHA would be more accurate for the nutritional analysis of bee pollen. Here we present a simple, sensitive, and reliable method for the determination of AA, total ascorbic acids (TAA), and DHA in rape (Brassica campestris), lotus (Nelumbo nucifera), and camellia (Camellia japonica) bee pollen, which is based on ultrasonic extraction in metaphosphoric acid solution, and analysis using hydrophilic interaction liquid chromatography (HILIC)-ultraviolet detection. Analytical performance of the method was evaluated and validated, then the proposed method was successfully applied in twenty-one bee pollen samples. Results indicated that contents of AA were in the range of 17.54 to 94.01 µg/g, 66.01 to 111.66 µg/g, and 90.04 to 313.02 µg/g for rape, lotus, and camellia bee pollen, respectively. In addition, percentages of DHA in TAA showed good intra-species consistency, with values of 13.7%, 16.5%, and 7.6% in rape, lotus, and camellia bee pollen, respectively. This is the first report on the discriminative determination between AA and DHA in bee pollen matrices. The proposed method would be valuable for the nutritional analysis of bee pollen.

ANALISIS KANDUNGAN ASAM ASKORBAT PADA TANAMAN KANGKUNG (Ipomoea reptana Poir), BAYAM (Amaranthus spinosus), dan KETIMUN (Cucumis sativus L)

Plants have a defense mechanism against increasing oxidative compounds formed due to drought stress. One of the compounds forming these compounds is ascorbic acid. Ascorbate is the main metabolite compound in plants that has an antioxidant function, which protects plants from oxidative damage resulting from aerobic metabolism. The aim of the study was to standardize and analyze the content of Ascorbate (ASA) on the leaves of kale (Ipomoea reptana Poir), spinach (Amaranthus spinosus) and cucumber (Cucumis sativus, L). The method used was 0.5 g leaf samples were crushed with 5% metaphosphoric acid. The solution obtained was titrated with dichlorophenol-indophenol (DCIP) 0.8 g / l. Treatment analysis of ascorbic acid (ASA) content in this plant tissue which has the largest ascorbic acid content in cucumber plants (Cucumis sativus L) of 69855.85; then followed by spinach plants (Ipomoea reptana Poir) at 66517.24 and finally in spinach (Amaranthus spinosus) at 38859.13. And the ASA mg standard 308.

Development of a Stability Indicating Method for Simultaneous Analysis of Five Water-Soluble Vitamins by Liquid Chromatography

Background Water-soluble vitamins are often included simultaneously in pharmaceutical formulations as food complements or in parenteral nutrition mixtures. Given their sensitivity to heat, light or pH variations, it is important to study their stability using validated stability indicating methods. We thus aimed to validate a liquid chromatography (LC) stability-indicating method for the simultaneous quantification of 5 water-soluble vitamins. Methods We analyzed four water-soluble B vitamins (nicotinamide, pyridoxine, folic acid, cyanocobalamin) and ascorbic acid using a LC method with diode array detector. They were separated on a C18 stationary phase under gradient elution of solvent A [0.2 % of metaphosphoric acid in water and acetonitrile 98:2] and solvent B (100 % acetonitrile). All vitamins were subjected to forced degradation conditions and we showed that the obtained degradation products didn’t interfere with the vitamins. Results The method allows the separation of the 5 water-soluble vitamins in a 30 minute run without any interference from the breakdown products obtained with acid/alkaline solutions, hydrogen peroxide, temperature and light. It meets all the qualitative and quantitative criteria for validation with an acceptable accuracy and good linearity. Conclusions This stability-indicating method can be used for carrying out stability studies of water-soluble vitamins in pharmaceutical preparations.

A Convenient and Sensitive LC-MS/MS Method for Simultaneous Determination of Carbadox- and Olaquindox-Related Residues in Swine Muscle and Liver Tissues

This paper presents a convenient and sensitive LC-MS/MS method for the simultaneous determination of carbadox and olaquindox residues, including desoxyolaquindox (DOLQ), desoxycarbadox (DCBX), quinoxaline-2-carboxylic acid (QCA), 3-methyl-quinoxaline-2-carboxylic acid (MQCA), and the glycine conjugates of QCA and MQCA (namely, QCA-glycine and MQCA-glycine, resp.) in swine muscle and liver tissues. Tissue samples were extracted with 2% metaphosphoric acid in 20% methanol and cleaned up by solid-phase extraction (SPE) on a mixed-mode anion-exchange column (Oasis MAX). Analysis was performed on a C18 column by detection with mass spectrometry in the multiple reaction monitoring (MRM) mode. The limits of detection (LODs) of the six analytes were determined to be 0.01 μg·kg−1 to 0.25 μg·kg−1, and the limits of quantification (LOQs) were 0.02 μg·kg−1 to 0.5 μg·kg−1. The total recoveries of the six analytes in all tissues were higher than 79.1% with the RSD% less than 9.2%. The developed method can determine the real residue level of QCA and MQCA, whether they are present in free form or as glycine conjugates in tissues, together with the carcinogenic desoxy metabolites DCBX and DOLQ with high recovery. Therefore, this method was suitable for routine analysis of residue control programmes and the residue depletion study of CBX and OLQ on swine.

Ácido Fítico e Ácido Metafosfórico como Agentes Alternativos para Condicionamento Dentinário: uma Revisão da Literatura

O objetivo do presente estudo foi realizar uma revisão de literatura sobre a ação do ácido fítico (IP6) e do ácido metafosfórico (MPA) como agentes condicionantes em dentina e avaliar seus respectivos resultados. Foi realizada uma busca nas bases de dados Pubmed, e Science Direct, entre 2013 e 2017, utilizando os descritores, separados e em combinação, “Phytic acid”, “Metaphosphoric acid” e “Dentin”. Foram obtidos 12 artigos no total, desses 3 estavam repetidos e foram excluídos. Dos demais, 8 eram estudos in vitro e 1 era revisão de literatura. Através de uma leitura crítica dos títulos e dos resumos, foram selecionados 6, relevantes ao tema. Artigos de revisão de literatura e que não se adequavam ao objetivo do trabalho foram excluídos. Muitas estratégias são testadas com a finalidade de aumentar a longevidade das interfaces adesivas, recentemente foi proposto que IP6 e MPA poderiam ser usados como agente de condicionamento dentinário. O uso do MPA, os valores de resistência de união são melhores que os obtidos com o ácido ortofosfórico (OPA), padrão-ouro odontológico, além disso, é possível observar que o MPA desmineraliza menos a dentina que o OPA, além de formar o mineral bruxita que melhora a durabilidade da interface adesiva. Os achados em relação ao IP6 também apontam para valores de resistência de união similares ao PA, além da menor susceptibilidade de degradação colagenolítica, por possuir ação biomodificadora. São necessários mais estudos que comprovem a eficiência de tais materiais como agentes condicionantes, assim como, a aplicabilidade clínica.Palavras-chave: Phytic Acid. Metaphosphoric Acid. Dentin.

Determination of Vitamin C in Various Colours of Bell Pepper (Capsicum annuum L.) by Titration Method

Vitamin C is needed by human body to improve the immune system and can be obtained from the bell pepper. Bell pepper has a different color according to the level of maturity, ranging from green, yellow, orange, and red. Differences in color also make possible differences in vitamin C content. The purpose of this study was to determine vitamin C levels in various colors of bell fruit. Measurement of vitamin C was done by titration method with metaphosphoric acid as the solvent and 2,6 dichloroindophenol as the standardized solution. The samples used were green bell pepper, yellow bell pepper, orange bell pepper, and red bell pepper taken from Gundaling, Berastagi, Karo, Sumatera Utara, 22152, Indonesia. The results show that vitamin C level in various colors of bell pepper respectively, for green bell pepper 16.52 mg vitamin C per 100 g green bell pepper; yellow bell pepper 159.61 vitamin C per 100 g yellow bell pepper; orange bell pepper 121.38 vitamin C per 100g orange bell pepper; red bell pepper 81.19 vitamin C per 100 g red bell pepper. These results indicate that different levels of bell pepper maturity have different vitamin C content.