Material Identification

Independent of the type of scoring system used, there is always a risk of obtaining a false identification result. Each measured spectra can match the frequencies of several different molecules in addition to the match with the molecule actually present in the sample. False results are caused by the accidental matching of the frequencies of a chemical with no properties similar to the unknown. An incorrect result is also obtained when the score due to random matching cannot be discerned from the score match due to matching of the real spectra in the sample. It is therefore useful to include other information when interpreting the quality of the match, such as the chemistry involved in the unknown sample. The likelihood of accidental matches (and hence the likelihood of false identification) increases if the spectral reproducibility is reduced. 

The Sadder division of Bio-Rad Laboratories (http // www.sadtler.com) has a product on compact disc containing 175,000 IR and 3,300 Raman spectra. For a subscription price the user gets the disc and an e-mailed code from Sadder that opens the disc for searches on one computer for a year. Once the code opens the disc, the user may perform unlimited lookups on one computer for one year. A lookup retrieves spectra by names or structures for comparison. In addition, the user may perform unlimited searches to identify or classify unknowns. Other databases for 

It is necessary to be able to identify and quantify the additives in polymers and vibrational spectroscopy is a particularly useful approach to this problem. Compared with traditional chemical analyses, vibrational methods are nondestructive and are time-and cost-effective as well as more precise. A large number of examples exist in the literature. For example, antistatic agents (polyethylene glycol (PEG) in polyethylene (PE)) can be detected directly using FTIR sampling (367). An IR spectroscopic technique for the analysis of stabilisers (2, 6-di-tert-butyM-methylphenol) in PE and ethylene-vinyl acetate (EVA) copolymer has been described (368). It is possible to quantify the amount of external and internal lubricants (stearic acid in polystyrene (PS)) (371). Fillers in polymers can also be analysed (white rice husk ash (predominantly silica in polypropylene (PP)) (268). Raman spectroscopy has been used to detect residual monomer in solid polymethyl methacrylate (PMMA) samples (326). 

It is also possible to determine multiadditives in the same sample using FTIR and multivariate analysis methods. For example, the simultaneous determination of the concentrations of silica, erucamide and butylhydroxytoluene in PE were measured using IR spectroscopy and suitable calibration models. The concentrations were between 20 and 1100 wt/ppm (366). A multiadditive method was developed for characterisation of an antiblocking agent (silica) and lubricant (erucamide) in molten low density polyethylene (LDPE) samples (324). 

A surface method of measurement of a sizing agent (partly hydrolysed polyvinyl alcohol) on the warp yam substrate (polyester/cotton) using NIR diffuse reflectance spectroscopy has been described (337). A partial least-squares (PLS) modelling procedure used a frequency segment of the NIR spectrum that is most sensitive to changes in size concentration relative to the warp yarn. 

As remarked earlier, greater loadings are required for cross-linked samples than for the corresponding uncross-linked material in order to achieve sufficient penetration to adequately detect the crystalline melting point with confidence. TMA data would typically be used in conjunction with some or all of FTIR spectra, DSC responses and also data from thermogravimetric analysis (TGA) as appropriate, in order to more fully characterise an unknown. 

A knowledge of the properties of the materials available, or provision of reference samples where some material fault is suspected, greatly facilitates this type of work. It is a great advantage, therefore, to log all thermal analysis experiments and to archive all data for future reference. These will, at some time, amply repay the analyst in interpretation of 

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SGN—M System of Materials Identification, brochure, Canadian Fertilizer Institute, Ottawa, Ontario, Canada, 1982. 

Fabrication tolerances are covered in this subsection. The tolerances permitted for shells for external pressure are much closer than those for internal pressure because the stability of the structure is dependent on the symmetry. Other paragraphs cover repair of defects during fabrication, material identification, heat treatment, and impact testing. 

How do you ensure traceability of product to original material identification, quality status, and the unit responsible for both its supply and verification ... 

Do specify the product identification details in the product specification and denote where and with what materials identification is to be applied. 

Anecdotal evidence exists that some companies have relaxed their material identification programs when their suppliers systems comply with quality standards. In view of the serious results of occasional minor errors—minor from the suppliers point of view—it is doubtful if this is wise. 

Products manufactured using concepts in UL Standard 746D provide quick verification of material identification, along with the assurance that acceptable blending or simple compounding operations are used that would not increase the risk of fire, electrical shock, or personal injury. 

The user can find suitable materials in a number of different ways. For instance any of the above measurands can be chosen and a search made within a specific matrix type. A list of the measurand values in all materials of the selected matrix classification sorted by decreasing concentration will be produced, including the uncertainties in percent, the certification status and the material identification code. Other search methods are possible, selection by material gives a table with values of all measurands in the chosen material in alphabetical order and additional information about the price, the unit size, the issuing date, the supphers and the exact material name. A further option is to list all materials from a producer. 

Fingerprinting materials, identification of bulk additives such as plasticisers and fillers. Non-destructive examination of samples... 

Sidwell and Zondervan [10] used LC-MS with APCI detection for the identification and quantification of extractable antioxidants from food-contact plastic materials. Identification is based on the presence of the molecular ion (M + FI)+, (M—H) , other key ions or on further ion breakdown (MSn) transitions. The following antioxidant/stabiliser types were examined hindered phenols,... 

In the following sections, common features of gas chromatographic procedures applied to proteinaceous material identification in paint are discussed such as sample pretreatments and data analysis. Finally, a section is devoted to the recognition of the amino acid racemisation in ancient proteins encountered mostly in archaeological contexts. 

CAS registry number An identifying numberi ng system for chemicals called the Chemical Abstract Service (CAS) with individual numbers assigned by the American Chemical Society. CAS numbers identify specific chemicals and are assigned sequentially. Such a number is a concise and unique means of material identification. 

C.A.S. Registration Number Chemical Abstracts Service. An assigned number used to identify a material. CAS numbers identify specific chemicals and are assigned sequentially the number is a concise, unique means of material identification. A product of more than one component will have a specific number for each component (i.e., the CAS for lethal nerve agent GA, or tabun, is 77-81-9 while the CAS for the liquid nerve agent GB, or sarin, is 107-44-8, and 50.642-23-4). 

Also, the high mobility present in elastomers creats a weak dipolar coupling so that the cross polarization is inefficient and results in weak enhancement compared to standard free induction decay spectra. As far as material identification is concerned, the spectrum resulting from acquiring a standard pulsed free induction decay at an elevated temperature is adequate. Further research will probably show the narrow lines from the magic angle spectra of natural rubber may allow assignments to lesser components. ... 

High-resolution 13C NMR studies have been conducted on intact cuticles from limes, suberized cell walls from potatoes, and insoluble residues that remain after chemical depolymerization treatments of these materials. Identification and quantitation of the major functional moieties in cutin and suberin have been accomplished with cross-polarization magic-angle spinning as well as direct polarization methods. Evidence for polyester crosslinks and details of the interactions among polyester, wax, and cell-wall components have come from a variety of spin-relaxation measurements. Structural models for these protective plant biopolymers have been evaluated in light of the NMR results. 

A Hazardous Materials Identification System (HMIS) for glacial acetic acid. 

A Hazardous Materials Identification System (HMIS) for glacial acetic acid B Definition of the hazard index and personal protection index HMIS is copyrighted by the National Paint and Coatings Association and marketed exclusively through Labelmaster, Chicago, IL... 

Spatially resolved material identification and classification is currently the prevalent application for SI systems. Of the many powerful spectral classifiers available, only two types, each with a number of different algorithms,14 could successfully be applied for real-time SI applications discriminant classifiers and dissimilarity-based classifiers. In addition, occasionally dedicated algorithms, such as fuzzy-classifiers, may be useful for special applications, for example, when there is no ab inito knowledge about the number and properties of the classification classes. 

Nonmetallic Inorganic Solids. This category includes many items of forensic importance ceramic and glasses naturally occurring substances such as building and insulation materials and soil components additives to papers, paints, explosives, drugs and many other materials. In contrast to metals, even the task of basic material identification often requires considerably more than the overall chemical analysis for these substances. 

It is an empirical finding that the diffraction patterns of many organic explosives display prominent diffraction peaks that lend themselves to material identification [13]. XDI is sensitive to a wide range of explosives, and its low false-alarm rate (FAR) when confronted with the harmless materials that comprise the vast majority of suitcase contents is unsurpassed by alternative bulk detection techniques. 

The wavelength, A, is often the Cu Ka line at 0.154 nm. Primary information for material identification is provided by relative peak heights and peak positions. The latter is illustrated in Eq. 5, in which x is the momentum transfer, inversely proportional to the d-spacing at constant order, n. 

Provide positive material identification and to check the quality of all incoming material used for pressure containment systems in this process. 

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