Tape analysis

Maynard, P., et aL "Adhesive Tape Analysis Establishing the Evidential Value of Specific Techniques." Journal of Forensic Sciences 46 (2001), 280-287. 

For many reasons, it may be ineonvenient to take the speetrum analyzer to the field eaeh time an analysis is to be made. Often, several maehines are to be analyzed at various loeations. Also, a hostile environment may exist at the test site, whieh might result in damage to the analyzer. A way of over-eoming these problems is offered by data taping. With a tape, a permanent reeord is made. Sinee eaeh ehannel of the tape offers a plaee for data to be stored, this reeord may be a eondensation of several inputs either from different transdueers or from the same transdueer at various loeations. A eontinuous tape monitor is very benefieial. In the event of maehine failure, an analysis of the playbaek will help diagnose the problem. 

Corrective Action Application Case 1 - Groundwater at the MEMOREX Computer Tape Plant (Santa Clara, California) was contaminated by a leaking underground solvent storage tank (Skladany et al., 1987). Chemical analysis of the groundwater identified the presence of methyl ethyl ketone (MEK) up to 500 ppm xylenes together with ethyl benzene up to 40 ppm cyclohexanone up to 30 ppm cyclohexanol up to 10 ppm acetone up to 10 ppm and toluene, tetrahydrofuran, 2-butanol, and methyl propyl ketone each less than 1 ppm. A biological... 

If further resolution is necessary one-third octave filters can be used but the number of required measurements is most unwieldy. It may be necessary to record the noise onto tape loops for the repeated re-analysis that is necessary. One-third octave filters are commonly used for building acoustics, and narrow-band real-time analysis can be employed. This is the fastest of the methods and is the most suitable for transient noises. Narrow-band analysis uses a VDU to show the graphical results of the fast Fourier transform and can also display octave or one-third octave bar graphs. 

Steam condensate samples should be cooled in a stainless steel sample cooler. Samples should be run for 5 to 10 minutes before being collected in a 100-ml amber glass jar with a Teflon lid. The jar should be filled completely with no air space, but without over flowing. The cap should be tight, taped if necessary, and the sample kept cool prior to laboratory analysis. 

Tape >System of Analysis. A tape system which is used widely for analysis in the Pediatric Laboratory is a system whose principle was developed by the author. A reagent is placed on a paper tape. The paper is covered with a membrane, such as cellophane, cellulose nitrate or cellulose acetate, porous to low molecular weight substances. Finally, the serum is placed above the porous membrane, so that diffusion of the components of serum take place and a stain is produced on the paper (60). This principle has been incorporated for example, with glucose oxidase, in the conmercially available Dextro-Sticks. In addition, a similar principle is being applied by some for the analysis of components in urine (Ames Co., South Bend, Indiana). 

Figure 41, The principle of the tape system of analysis. The three tapes are the reagent tape on the bottom, cellopnarie in the center, and sample tape on top. The sample placed on the top tape folds over and is pressed by the press plate and warmed so that the material dialyses through the membrane. The stain is then formed and is read by reflecting densitometry on the reagent tape.

Successful combination of a chromatographic procedure for separating and isolating additive components with an on-line method for obtaining the IR spectrum enables detailed compositional and structural information to be obtained in a relatively short time frame, as shown in the case of additives in PP [501], and of a plasticiser (DEHP) and an aromatic phenyl phosphate flame retardant in a PVC fabric [502], RPLC-TSP-FTIR with diffuse reflectance detection has been used for dye analysis [512], The HPLC-separated components were deposited as a series of concentrated spots on a moving tape. HPLC-TSP-FTIR has analysed polystyrene samples [513,514], The LC Transform has also been employed for the identification of a stain in carpet yarn [515] and a contaminant in a multiwire cable [516], HPLC-FTIR can be used to maintain consistency of raw materials or to characterise a performance difference. 

Rtihl [141] has reported on very large scale SS-GFAAS and XRF analysis of Cd in polymers for product control purposes in the automobile industry (approximately 20 000 parts per year) as a reaction on a Swedish law for environmental protection (upper limit of 75ppm). Another sample of direct SS-GFAAS in industry is the control of all raw materials, processing steps, and products for adhesive tapes for the content of Cu, Mn, Fe, Cd and Pb, which act as a rubber poison by catalytic effects [144]. 

It is interesting to trace the development of instrument automation over the relatively brief period of the past ten to fifteen years. Early in this period, a truly automated instrument was a rare and expensive item built around a costly dedicated minicomputer. Automated data collection and analysis from any instrument which was not automated at the factory was usually accomplished by digitizing the data and storing it on a transportable media such as paper tape. These data were then delivered and fed to a timeshare system of some sort on which the data reduction program ran and which printed a report and sometimes a plot of the data. Often a considerable time delay occured between the generation and the analysis of the data. The scientist was at the mercy of the computer elite who could implement his data logger and provide the necessary computer resources to analyze his data. The process was expensive, both in time and in money. 

Figure 2 shows the SEM image of the flake at a magnification of 350 x, as it was mounted on the conductive carbon tape. If there is a polymeric film covering the sample, the SEM will only show the surface topography of the film, not the structure residing below the polymeric film. EDS was conducted on two areas on the sample as indicated in Figure 2. The EDS analysis was conducted in square spot mode, approximately 1 pm by 1 pm in size. The elemental results are shown in Table 2. Based on these data sets it is apparent that the Type A defect is an iron-rich particle. Based on the lack of chromium or nickel the Type A defect is a particle of steel, not stainless steel.

A section of the film was removed from the bag and was immersed in liquid nitrogen. The section was then freeze-fractured and mounted on the SEM stage with the outside surface of the bag section facing downward. The sample was sputter coated prior to SEM/EDS analysis. Sputtering was performed to deposit approximately 20 nm of gold/palladium onto the sample. Double-sided conductive tape was used to ensure that the sample was sufficiently grounded to... 

Urocanic acid (2-propanoic acid 3-[lH-imidazol-4-yl] is located superficially in the stratum comeum. Metabolism of epidermal UCA does not occur in situ due to the absence of urocanase, resulting in the accumulation of UCA in the epidermis. Upon UV exposure, naturally occurring trans-UCA converts to the d.s-isomer, in a dose dependent manner, until the photostationary state is reached, when equal quantities of trans- and m-UCA are found in the skin.15 Based on an analysis of the action spectrum for UV-induced immune suppression, and the fact that no immune suppression was observed in mice whose stratum comeum was previously removed by tape stripping, De Fabo and Noonan suggested that urocanic acid was the photoreceptor for UV-induced immune suppression.16 Since the initial experiments many others have documented, the ability of ris-UCA to initiate immune suppression, documented its presence in the serum of UV-irradiated mice, and demonstrated that m-UCA plays a role in UV-induced skin cancer induction. (For a more complete review of the role of m-UCA in immune suppression see two excellent reviews by Norval and colleagues.1718)... 

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