Sample types vegetation

The average recoveries and standard deviations for the many citrus, pome fruit, tree nut, fruiting vegetables, and cotton substrate sample types were acceptable when fortified at concentration levels ranging from 0.01 to 4 mg kg. The LOQ of the method was 0.01 mgkg , except for citrus oil (0.02mgkg Q, and the LOD was 1.25 ng injected. 

Rapeseed oil and its fatty acids (stearic, palmitic, oleic, linoleic, and linolenic acids) were chosen as the samples of vegetable oil. The experiments were performed in the batch- and flow-type supercritical biomass conversion systems developed in our laboratory. For the batch-type system, a reaction vessel was made of Inconel-625 with a volume of 5 mL for the flow-type system, the supercritical treatment tube was constructed from Hastelloy stainless steel (HC 276) with length of 84 m and an id of 1.2 mm, with the total volume being about 95 mL. Detailed information about the equipment can be found elsewhere (13). 

Principal inorganic components detected by polaro-graphy are metallic species and certain anions. These applications will be described with respect to periodic elemental groupings. Determination of such analytes have been carried out in a wide variety of sample types such as water (waste and potable), foods (drinks, oils, meat, fruits, vegetables, and cereals), mineral ores, metallurgy, biological fluids (blood, urine), and environmental samples (sediments, soils, aerosols, and natural waters). 

The sample preparation was very simple the sample was centrifuged to remove plant cell residues and 10 pi of the clear juice was placed on the column. This type of separation is common with fruits, vegetables and juices and samples can be obtained by preliminary homogenizing the total tissues and then centrifuging. If it is suspected that the residue still contains significant quantities of the substances of interest, then it can be washed with water or if necessary with solvents and the washings combined with the separated supernatant liquor. The results obtained are shown in figure 15. 

In the characterization of alkyd resin formulations the palmitic acid to stearic acid (P/S) ratio, often used to identify the type of oil in a binder, cannot be applied as many different oils other than the traditional ones are commonly employed in industrial formulations. Moreover, they are often in mixtures, with the additional complication that fatty acids are also sometime added to the vegetable oils, thus making it impossible to rely on measured P/S values. In any case it is important to always derivatize the samples if Py-GC/MS is used and an alkyd is suspected. Phthalic anhydride will be detected also in an underivatized alkyd pyrogram however, isophthalic acid will not, leading to confusion and the possibility of uncorrected identification [92]. 

Fig. 1. The vegetative types of the Sakaerat Environmental Research Station (SERS) and the sampling points. DDF and DEF indicate dry deciduous forest and dry evergreen forest, respectively.

Lipids from liquid samples or cell suspensions may be extracted directly into organic solvents but solid samples will require prior treatment, such as homogenization or ultrasonication. The solvents are chosen with reference to the nature of the lipids present and to some extent, the type of sample, e.g. animal or vegetable tissue. Ethanol-diethyl ether (3 1) with subsequent extraction... 

The current individual methods differ in procedure, compounds detected, extraction techniques, and extraction solvents used. Some methods may include a cleanup step to remove biogenic (bacterial or vegetation-derived) material, while others do not. The methods have in common a boiling point type of column and a flame ionization detector. Selection of a method depends on the type of hydrocarbon suspected to be in the sample. 

GC/ECD is the method used to detect heptachlor and heptachlor epoxide in foods (butterfat, fruits, vegetables, milk, and animal feed) (Di Muccio et al. 1988 Hopper and Griffitt 1987 Korfmacher et al. 1987 Ober et al. 1987 Santa Maria et al. 1986). Preparation methods vary for the different types of foods. The sample preparation method for butterfat involves GPC. GPC is a rapid clean-up... 

Source Componnds detected in major formulations and products are included, e.g., benzene detected in air, water, or soil samples may be related or have originated from various types of petroleum spills such as gasoline or diesel fuel. In some instances, the compound of concern may be an impurity in the material released to the enviromnent or it may be naturally present in various types of vegetation. 

Bulk sensors certainly have a role in chemical sensing of explosives, but the subject of this book is the other basic type sensor, one that seeks molecules released from the bulk of the explosive material in an object. We will refer to these as trace chemical sensors. They are sometimes called vapor sensors, but that seems a less accurate description when they are applied to explosive molecules, which may not always be found in a vapor state. As we shall see in Chapter 5, that requires us to understand where and how to look for these molecules. It will become apparent upon a little reflection that the two types of sensors are complementary and are best used in different situations. Furthermore, even when trace sensors are used, in some situations sampling of particles of soil or vegetation or sampling from surfaces may prove to be more productive that vapor sampling. For underwater sources the term vapor sensing is also inappropriate. 

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