Fruit material, sample preparation

Fourier-transform (FT), 33 Fourier-transfonn infrared (FTIR) spectroscopy, 221-222,224,225,940 evaluation of thin-layer chromatogram, 147 Fruit material, sample preparation of, 484 Fungicides ... 

The study of obsidian by NAA has proved to be particularly fruitful because of the relatively limited number of sources and the extent to which it was traded (Beardsley et al. 1996, Cook 1995, Darling and Hayashida 1995, Kuzmin et al. 2002, Leach 1996). Studies have also extended to include other volcanic materials such as pumice (Bichler et al. 1997, Peltz et al. 1999). NAA has also been used for the analysis of flint as OES is insensitive and not reproducible due to the effect of the high silica content, and AAS requires significant sample preparation (Aspinall and Feather 1972). The wide range of appropriate materials extends to organic materials such as human bone (Farnum et al. 1995), and its exceptional sensitivity to trace elements has led to its wide use in geochemistry (for example in determining trace [ppb] contaminants in waters) and more recently in forensic chemistry. 

The ultrasound-assisted extraction of freeze-dried plant-based materials normally takes 2 hr. If the extract is evaporated to dryness, a total of 3 hr is necessary. As an additional sample preparation step, 2 to 4 days should be allotted for freeze-drying fresh plant materials, depending on the quantity of the material. Homogenizer-assisted extraction of fresh fruit takes <4 hr. 

As with all methods, this approach has some limitations it uses acetonitrile, which is toxic, and the separation of glucose from fructose can sometimes be problematic after extended use of the column. However, sample preparation is easy since it requires only dilution to the required level (often 1 10) and filtration prior to analysis to remove particulate materials, which protects and extends the useful life of the column. The degradation of the resolution between glucose and fructose is caused by the partial inactivation of the column by materials in the matrix, but this resolution can be recovered by reducing the acetonitrile concentration in the solvent. The same column can also be used to assay the level of ascorbic acid (vitamin C) in a soft drink or fruit juice, although different detection and solvent systems are used. 

Materials. Samples were obtained from a variety of sources. Fruits and juices were purchased locally. All oils, peanut butter, and food starch samples were supplied by food processors. Flavor compounds used in the preparation of standards were... 

Ion-exclusion chromatography finds numerous applications for identification and determination of acidic species in complex matrix materials, such as dairy products, coffee, wine, beer, fruit juice, and other commercial products which can be quickly analyzed with minimal sample preparation before injection (usually only filtration, dilution, or centrifugation). Organic acid determination is also of great importance in biomedical research (e.g., physiological samples, in which most of the Krebs cycle acids (tricarboxylic acid cycle) are present). 

In addition to seeds, other plant parts as leaves, stems, bark, roots, bulbs, and tubers are tested The ELISA procedures used for the various products will be mainly the same. However, sample preparation varies widely among plant species and plant parts In the Netherlands, the Pollflhne press is the most popular tool to prepare extracts. Relatively dry plant parts such as the leaves of some fruit trees, bark material, roots, bulbs and tubers are extracted by adding buffer to the press just above the sample during grinding. 

MSPD is the next alternative for sample preparation of fruits, vegetables, herbs, cereals, and other plants. It is convenient for liquid and semi-liquid samples. This technique is a multi-residual assay which consists of matrix homogenization with a solid silica phase placed into a short column, as in SPE. Analytes and matrix interferences are retained on the mixed solid-phase material with completely new separation characteristics. Specific elution allows one to obtain analytes after the elimination of matrix compounds via washing steps. This... 

Sample preparation Blend 500 mg chopped fruit or vegetable with 500 mg 45-55 (jini C8 re versed-phase material in a mortar and pestle for 5 min, place in a 100 x 9 glass column, elute with 10 mL MeCNidichloromethane 40 60. Concentrate the eluate to 500 (jiL under a stream of nitrogen, inject a 5 (aL aliquot. 

Each sample was analysed by means of NIR spectroscopy and attenuated total reflectance mid-infrared (ATR-MIR) spectroscopy. In particular, NIR and MIR spectra were collected in the spectral regions from 10000 to 4150 cm (with a resolution of 4 cm ) and from 4000 to 600 cm (with a resolution of 4 cm ), respectively. These techniques are very common in food and raw materials characterisation, since they are fast, non-destructive, low cost, and do not require a preliminary sample preparation [54,55]. Moreover, multivariate data analysis is extensively and fruitfully applied on NIR and MIR signals with the aim to extract and visualise relevant information [56,57]. 

Vegetables and fruits are prepared as appropriate for typical in home preparation methods (e.g., by removal of outside leaves, peeling, coring). Larger items such as cabbages, may be quartered, and then one quarter from each of the individual samples cut and mixed. Smaller items are cut and mixed. Further subsamples of the individual samples (e.g., 100 g depending on the number of individual samples collected initially) of the cut mixed materials are taken and these subsamples bulked and thoroughly mixed. 

Photoelectron spectroscopy (PES) has become an important and widely used tool in material science (1-3). It has been a particularly fruitful technique for the investigation of polymers (4-9). In this review, we will focus on the application of photoelectron spectroscopy to the investigation of the interfaces between metals and polymers. These studies are directed primarily to understand the role of Interfacial chemistry in the adhesion between metals and polymers. Two aspects, which will be emphasized here, are the experimental approaches in PES studies of polymer/metal interfaces and the types of information accessible from the PES experiments. The experimental emphasis will be on preparation of appropriate samples for polymer/metal interface studies, practical problems... 

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