Field-collected samples

The ASTM-EFA standard method of analyzing lead In gasoline requires extraction of alkyl lead Iodide complexes Into methyllsobutylketone and a subsequent flame atomic absorption analysis of the extract A more direct method has been proposed ( ) which uses Zeeman atomic absorption analysis after sample dilution. Both methods were used to analyze a set of five field collected samples. The results showed a bias (average difference between method results) of 0.0012 g/gal with the standard flame results higher. The correlation coefficient between the results was 0.9998 0.0009, and a pairwise t-test showed no difference between the methods (6). 

In a letter to Nature, Dr. L. Scott Mills, director of the laboratory that analyzed the samples, stated that the protocol used for the lynx survey had been validated with appropriate controls in two labs. His testing protocol had been peer reviewed and published. He said, For a field worker to arbitrarily decide to test the lab by labeling a hair from elsewhere as if it were a field-collected sample corrupts the integrity of the data and does not constitute a blind control. 7... 

The FSTR ( Freshwater Salinity Toxicity Relationship ) model (Mount et al., 1997) was also applied with selected Daphnia magna samples. The results indicated that for most samples, the model accurately predicted toxicity. Percent differences between measured and predicted TUs were generally less than or equal to 20%. In several cases the model either over- or under-estimated toxicity. Its failure to consistently predict mortality was supported by Mount et al. (1997), who observed that in its preliminary application in field-collected samples, the Daphnia magna model tended to over-predict toxicity. Alternatively, the presence of Cu could also explain why measured toxicity was occasionally higher than the predicted toxicity. 

Field-collected sample of presumably clean (uncontaminated) sediment, selected for properties (e.g., particle size, compactness, total organic content) representing sediment conditions that closely match those of the sample(s) of test sediment except for the degree of chemical contaminants. It is often selected from a site that is uninfluenced or minimally influenced by the source(s) of anthropogenic contamination but within the general vicinity of the site(s) where samples of test sediment are collected. A reference sediment should not produce a toxic effect (or have a minimum effect) on a test species. A sample of reference sediment should be included in each series of toxicity tests with test sediment(s). See also Artificial sediment, Positive control sediment and Test sediment. Volume 1(2,13), Volume 2(8). 

Field-collected sample of whole sediment, taken from a marine, estuarine, or freshwater site thought to be contaminated (or potentially so) with one or more chemicals, and intended for use in solid-phase toxicity tests. In some instances, the term also applies to any solid-phase sample (including reference sediment, artificial sediment, negative control sediment, positive control sediment, or dredged material) used in testing. Volume 1(2). 

Steglich [3] and Asakawa s group [4] have isolated several types of metabolites from field-collected samples of several myxomycete species. Cultivation of the plasmodium of myxomycetes in a considerable scale to cany out chemical studies is known only for... 

We also investigated field-collected samples of myxomycetes fruit bodies. TLC spot tests as well as antimicrobial activity tests were carried out on 13 species of wild myxomycetes. Chemical constituents of the field-collected samples of fruit bodies of Lindbladia tubulina,... 

Not aU field evidence supports the limitation of Trichodesmium diazotrophy by Fe. Both Karl et al. (1997) and Sanudo-Wifriehny et al. (2001) observed that median Fe concentrations <1 nM Fe did not seem to hmit N2 fixation in field collected samples in the subtropical North Pacific Ocean and the Central Adantic. It has been observed that there is no close correlation between total dissolved Fe and Trichodesmium abundance in the North Atlantic Ocean when only open ocean stations are considered, and little difference between total Fe concentrations where Trichodesmium is abundant and where it is scarce (Tyrrell et al., 2003). Moisander et al. (2003) noticed that in the Baltic Sea, Fe addition did not show a significant impact on N2 fixation or biomass production by three other genera of N2-fixing cyanobacteria. 

Swartz, R.C., D.W. Schults, R.J. Ozretich, J.O. Lamberson, F.A. Cole, T.H. DeWitt, M.S. Redmond, and S.P. Ferraro. 1995. 2PAH A model to predict the toxicity of polynuclear aromatic hydrocarbon mixtures in field-collected samples. Environ. Toxicol. Chem. 11 1977-1987. 

Differentiation of field collected samples using an electronic nose... 

The types and amount of quality control used during the field component of a study can vary depending on the data requirements of the stu. At a minimum, field blanks should be used to identify any contamination either through direct contact or airborne exposure of the sample. Other quality control samples to be considered include equipment blanks, if the same sampling equipment is repetitively used, trip blanks (contaminant-free water samples which accompany the field collected samples from the field to the laboratory but are not exposed to the air), and positive control... 

The following experiments describe homemade sampling devices for collecting samples in the field. 

Permeation systems can be calibrated in the laboratory and then used in the field for sample collection for a fixed period of time, e.g., 8 hr or 7 days. The sampler is returned to the laboratory for analysis. These systems can be made for specific compounds by selecting the appropriate collection medium and the polymer membrane (Table 13-2). 

Document all field observations on the appropriate forms. Written and photographic documentation of the sampling locations should record the design and materials used for construction of the sampling location, the procedures used to collect samples, and any potential sources of contamination that may bias the sample results. 

Audits of each phase of the study should include personnel training, preparation of collection forms, application calibration, each sample collection procedure, sample transport, each type of chemical analysis, data recording, data entry, data verification and data storage. Data collection in the field is often tedious if automated logging devices are not in place. To ensure data integrity, the paper and ink used for field studies should be waterproof. Each data collection form should contain appropriate locations for information detailing the time and location of sample collection, sample transport and sample analysis. Data collection forms should be stored in an orderly fashion in a secure location immediately upon return of field teams from the field at the end of each day. It is also important for data quality for studies to collect necessary field data seven days per week when required. In our experience, poor study quality is likely when field sample and data collection do not proceed on weekends. 

Field recovery samples are an important part of the quality control in DFR studies. Field fortifications allow the experimental data to be corrected for losses at all phases of the study from collection through sample transport and storage. Fresh laboratory fortifications monitor losses due to the analytical phase. This section details how the field recovery process was handled in the oxamyl tomato DFR study. 

The goal of spray drift sampling is to obtain representative samples of the application being investigated while minimizing any bias introduced by the methods employed to collect those samples. Collected samples are used to investigate whether pesticide products are present in the environment and, if present, at what rates relative to the amount of product(s) applied to the spray area (the field, forest or other spray area). 

Field fortification samples are stored under various conditions in the fleld. Generally, after the weathering period is complete, the fleld fortification samples such as dosimeter sections are wrapped in aluminum foil, placed in a pre-labeled zip-type bag, and immediately placed on dry-ice in a cooler or in a freezer. Field fortification samples such as hand washes or face wipes are prepared in labeled jars, the lids are immediately taped with electrical tape, and the jars are placed in a zip-type bag and wrapped in bubble-pack and immediately placed in frozen storage. Air tubes or air filters are collected after weathering and wrapped so as to prevent breakage. These samples are then placed in a pre-labeled zip-type bag and immediately placed in frozen storage. 

BHA, BHT, PG, TBHQ and tocopherols) a variety of stationary phases, mobile phases and detectors can be used [711]. Common antibacterials such as carba-dox, thiamphenicol, furazolidone, oxolinic acid, sul-fadimethoxine, sulfaquinoxaline, nalidixic and piromidic acid can be analysed by GE-RPLC-UV (at 254 nm). Collaborative studies have been reported for the HPLC determination of the antimicrobial sodium benzoate in aqueous solutions [712], Plastics devices used for field collection of water samples may contain polymer additives (such as resorcinol monobenzoate, 2,4-dihydroxybenzophenone or bisphenol A) or cyanobac-terial microcystins [713],... 

ASTM. 1998e. ASTM E 1727. Standard practice for field collection of soil samples for lead determination by atomic spectrometry techniques. American Society for Testing and Materials. 

In connection with our field measurements, samples of geological materials were collected for analyses in the laboratory. Activity concentrations were measured by standard gamma spectrocqpy with a 90-cm3 Ge (Li) detector and a Canberra Model 8100 multichannel analyser. Details on calibration and procedure were published earlier (Stranden, 1985). Rn-222 exhalation measurements were also performed... 

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