Chemical Laboratory Sample Identifier

Chemical Laboratory Sample Identifier (LSI) An identifier that uniquely identifies a chemical sample. Although the format of sample identifier differs from organization to organization, it usually consists of five parts a prefix that specifies the sample s source (e.g., synthesized internally or acquired from external sources) a base that uniquely specifics parent structure a form that indicates whether a chemical sample is a free base or with salt, radiolabeled, or a formulation a parity bit checksum that is derived from the combination of prefix, base, and form using a check-sum hash algorithm and a batch or a lot number that identifies the actual physical sample. 

The soil sample was problematic in the second trial proficiency test. Only six of the 15 participating laboratories successfully identified both N,N-diethylaminoethanol (CAS 100-37-8) and A-ethyl-diethanolamine (EDEA, CAS 139-87-7). For these particular spiking chemicals, efficient TEA/methanol extraction followed by a silylation procedure was essential in the sample preparation. One laboratory missed both spiking chemicals, probably because TEA/methanol extraction was not carried out. Another laboratory also missed them but for a different reason. Instead of TEA, ethyldimethy-lamine (EDMA, CAS 598-56-1) was used as an extractant, and although this should not have had a dramatic effect on the recoveries of the spiking chemicals, since EDMA should be as good a modifier as TEA, the laboratory then derivatized the 1 % EDMA/methanol extract with BSTFA, thus removing any chance of success. Chemicals in alcohol solutions cannot be silylated, and this must... 

In the eleventh official proficiency test, one laboratory missed identifying ethylphosphonic acid (CAS 6779-09-5) in the water sample. Insufficient sample preparation may have been the reason, as the laboratory did not perform cation exchange for the sample before derivatization. Four laboratories successfully identified the chemical without cation... 

Samples of styrene butadiene rubber having known styrene content and identified as block copolymers were obtained from Aldrich Chemical Co. Samples of Cariflex SBR were obtained from the Los Angeles Customs laboratory. No specific information is known of additives for the samples except S-1502 which has an aromatic oil additive. Samples were cut into small cubes to fit into the balance pan and weighed between 3 and 12 milligrams. 

Rotational transitions correspond to photon wavelengths in the microwave region. The radiation sources in microwave spectrometers are klystron tubes, which were originally developed for radar apparatuses in World War II. Hollow metal wave guides carry the radiation to the sample cell, which is a hollow metal cavity, and the resonant radiation in the cavity is sampled to detect absorption. Microwave spectroscopy has played an important role in identifying molecules in interstellar space, but it is not a common tool in many chemical laboratories. 

Definitive information must be obtained about a munition before it can be dispatched to its storage location. Neutron activation analysis and tomography equipment must be available on site, for purposes as discussed above. In some cases, samples of liquid munition contents are taken by drilling into it with a hollow drill. It is necessary that conventional chemical laboratory analysis facilities (mass spectrometer, chromatography, data base, etc.) be available so that any suspect material can be identified. The chosen dismantling techniques will be all the more effective if they are applied to well defined families of objects. 

Pesticides used on crops grown on the test site in previous seasons may also have an impact on the outcome of a field residue trial. Carryover of prior pesticide applications could contaminate samples in a new trial, complicate the growth of the crop in a trial, or cause interference with procedures in the analytical laboratory. For this reason, an accurate history of what has transpired at the potential test site must be obtained before the trial is actually installed. The protocol should identify any chemicals of concern. If questions arise when the history is obtained, they should be reviewed with the Study Director prior to proceeding with the test site. In most annual crop trials, this will not be a significant issue owing to crop rotations in the normal production practices, because the use of short residual pesticides and different chemical classes is often required for each respective crop in the rotation. However, in many perennial crops (tree, vines, alfalfa, etc.) and monoculture row crops (cotton, sugarcane, etc.), the crop pesticide history will play a significant role in trial site selection. 

The ESRI experiments described in our publications and summarized in this chapter led to spatially resolved information on the effect of treatment conditions, amount of stabilizer, and polymer composition on the degradation rate. In the heterophasic systems studied in our laboratory, ESRI has identified specific morphological domains where chemical processes are accelerated. The combination of ID and 2D spectral-spatial ESRI experiments led to mapping of the stabilizer consumption on two length scales within the sample depth on the scale of a few mm, and within morphological domains on the scale of a few gm. 

Contamination assessment of an injured individual should be performed by a trained health professional under the supervision of on-the-scene medical personnel. This assessment should include collecting radiation and chemical agent measurements using instrumentation identified in Section 6.12, nasal wipes, and collection of saliva, blood, and other samples for laboratory testing. The distribution of contamination and locations of wounds on the body should be recorded. 

Several soil-vapor monitoring techniques are currendy being used to define areas of volatile organic chemical contamination. These procedures usually involve the collection of representative samples of the soil gas for analysis of indicator compounds. Maps marked with concentration contours of these indicator compounds can be used to identify potential sources to delineate the contaminated area. Indicator compounds (usually the more volatile compounds) are selected for each specific situation. For gasoline contamination, the compounds are usually benzene, toluene, ethylbenzene, and total xylene (BTEX). In the case of a fuel oil spill, the most commonly used indicator is naphthalene. Some laboratories have adapted the laboratory procedures used for quality analysis of wellhead condensate (i.e., normal paraffins) to include light-end (<8 carbons) molecular analysis. 

Laboratory-scale test procedures consisting of jar test studies have been used for years, and the test methodology developed is such that full-scale designs can be developed from these studies with a high degree of confidence. A jar test is a series of bench-scale laboratory procedures made on 1- or 2-1 water samples to determine the most effective water treatment method. Tests are performed to identify the most effective coagulants, optimum dosage, optimum pH, and most effective order in which to add various chemicals. 

Laboratory procedures may need to be evaluated against the sampling techniques and materials involved in the toll. There may be new laboratory chemicals and hazards to be considered. This work may have been identified in the evaluation of special analytical techniques required for the process. A good practice is to ensure that the lab technicians have the necessary guidance and types of equipment on hand to monitor the process and waste streams accurately and safely. 

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