Application of FTIR-ATR to discriminate peach nectars with higher and lower sugar contents

Fruit juice does not have the same nutritional value as fresh fruit with regards to the vitamin, mineral and dietary fibre contents and the antioxidant properties. However, it can be part of a healthy diet if it is produced with the minimal addition of sugar. This study aimed to evaluate the performance of the FTIR-ATR technique to discriminate the authenticity (concerning the addition of other pulps) and amount of sugar in peach nectars. This technique is usually used in food analysis because it does not require sample preparation, is quick and allows for the determination of several parameters with a single sample aliquot. The nutritional information provided on the labels of 69 samples of 23 different brands of commercial peach juice, was analysed. The differences in the nutritional composition and in the ingredients were determined according to an analysis of the labels. The largest differences observed between the samples were the sugar contents, the percentages of pulp and the addition of other pulps. All samples were analysed by FTIR-ATR equipped with a controlled temperature flow-through cell. The spectral multivariate analysis suggested it was possible to identify differences in the amount of sugar present and identify the presence of fruit pulps other than peach.

Efficient separation and high-precision analyses of tin and cadmium isotopes in geological materials

A novel analytical procedure using chromatographic separation and MC-ICP-MS for high precision Sn and Cd analyses on the same sample aliquot.

Precise isotope analysis of tellurium by inductively coupled plasma mass spectrometry using a double spike method

We present an analytical protocol to determine the Te/Se ratio and stable isotope composition of Te from a single sample aliquot.

Sequential separation of americium, curium, plutonium, neptunium and uranium in various matrices from the electrometallurgic treatment of spent-nuclear fuel

The separation of americium-241, curium-242/244, plutonium-238/239, neptunium-237, and uranium-234/235/238, in the same sample aliquot of clear acidic solution resulting from the electrometallurgical treatment of spent nuclear fuel has been investigated. Using ion exchange techniques in 10 M HCl media, it was determined that good separation can be achieved to resolve each isotope via alpha spectroscopy. The resin used was AG 1-x8 chloride form supplied by BioRad® Laboratories. The retention and eluting conditions for each isotope were determined using tracer techniques and will be presented. Based on this work, an analytical procedure for the sequential separation of Am, Cm, Pu, Np, and U, in various sample matrices recovered from the demonstration project is presented.

Aflatoxin, A Human Carcinogen: Determination in Foods and Biological Samples by Monoclonal Antibody Affinity Chromatography

We have used monoclonal antibody technology to produce antibodies that recognize aflatoxins in order to develop noninvasive methods in conjunction with other chemical analytical techniques to monitor human exposure to environmental carcinogens. These methods require the ability to quantitate aflatoxins and their metabolites, including DNA and protein adducts, in readily accessible compartments such as serum and urine. The techniques permit efficient analysis of many samples in a relatively short time. Also, these monoclonal antibody affinity columns have been extremely useful for rapid isolation of aflatoxins from food and grain samples, as well as aflatoxin M, from milk. Monoclonal antibody affinity methods are nondestructive to the aflatoxin molecule, so the sample aliquot can be used for confirmation. The use of monoclonal antibody preparative affinity columns represents a major, substantive breakthrough for analytical chemists and will be a generally applicable technology for isolation of many different substances.

Determination of N-Nitrosodimethylamine Levels in Some Canadian 2,4-D Amine Formulations

Levels of/V-nitrosodimethylamine (NDMA) were determined in 112 samples of 2,4-dichlorophenoxyacetic acid, (2,4-D), formulated as the dimethylamine salt, collected over a 2 year period from products on the Canadian market. A sample aliquot is partitioned with dichloromethane, and the co-extracted dimethylamine is removed by cleanup on a silica gel column. The eluates containing NDMA are concentrated, an internal standard of /V-nitrosodipropylamine is added, and nitrosamine levels are determined using a gas chromatograph interfaced with a thermal energy analyzer. Recoveries of NDMA and N-nitrosodiethylamine spiked into samples were 103 ± 16 and 96.3 ± 9.8%, respectively. Of the 112 samples analyzed, 92 were below 1 part per million (ppm) relative to the amount of 2,4-D in the samples, 16 were between 1 and 5 ppm, and 4 were greater than 5 ppm. The gas chromatographic column used is compared to a conventional packing material for volatile nitrosamine analysis. Formation of NDMA during cleanup and analysis was shown not to occur.

Improved Monomolecular Fat Film Method for Determination of Yolk in Egg Albumen

The monomolecular film method can be simplified by an improved quantitation procedure. Following the extraction of the fat from the albumen and subsequent evaporation, the redissolved sample is applied to a round glass plate containing 1 in. pH 5 acetic acid solution topped by a film of oxidized oil sufficient to exhibit a color of third order green. The sample aliquot is dropped from a 100 μL Hamilton syringe directly at the center of the oil surface. A circular pattern results. The diameter of the pattern is measured in centimeters with a ruler placed under the glass plate. The area of the pattern is then calculated by the formula for the area of a circle.