Sampling Handling

Samples that are liquid at room temperature are usually scanned in their next form or in solution. The sample concentration and path length should be ehosen so that the transmittance lies between 10 and 70%. For neat liquids, this 

One of two methods can be used to measure the path length of infrared absorption cells the interference fringe method or the standard absorber method. The interference fringe method is ideally suited to cells whose windows have a high polish. With the empty cell in the spectrophotometer on the sample side and no cell in the reference beam, the spectrophotometer is operated as near as possible to the 100% line. Enough spectrum is run to 

The standard absorber method can be used with a cell in any condition on cavity cells whose inner faces do not have a polished finish. The 1960-cm (5-10-pm) band of benzene can be used for calibrating cells less than 0.1 mm in path length, and the 845-cm (11.8-pm) and for cells 0.1 mm or longer in path length. At the former frequency, benzene has an absorbance of 0.10 for every 0.01 mm of thickness at 845 cm, benzene has an absorbance of 0.24 for every 0.1 mm of thickness. 

Spectra of liquids insoluble in a suitable solvent are best obtained from capillary films. A large drop of the neat liquid is placed between two roek salt plates that are then squeezed together and mounted in the speetrometer in a suitable holder. Plates need not have high polish, but they must be flat to avoid distorting the spectrum. 

For polymers, resins, and amorphous solids, the sample is dissolved in any reasonably volatile solvent, the solution poured onto a rock salt plate, and the solvent evaporated by gentle heating. If the solid is noncrystalline, a thin homogeneous film is deposited on the plate, which then can be mounted and scanned directly. Sometimes polymers can be hot pressed onto plates. 

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Porro, T. J. Pattacini, S. C. Sample Handling for Mid-Infrared Spectroscopy, Part 1 Solid and Liquid Sampling, Spectroscopy 1993, 8(7), 40-47. 

The ease of sample handling makes Raman spectroscopy increasingly preferred. Like infrared spectroscopy, Raman scattering can be used to identify functional groups commonly found in polymers, including aromaticity, double bonds, and C bond H stretches. More commonly, the Raman spectmm is used to characterize the degree of crystallinity or the orientation of the polymer chains in such stmctures as tubes, fibers (qv), sheets, powders, and films... 

Fig. 1. LIMS procedure flow chart (sample handling and reporting) (4).

Owing to the light and air sensitivity of the carotenoids and retinoids, sample handling is a critical issue. It is recommended to conduct extraction of these materials with peroxide-free solvents, to store biological samples at —70° C under argon and in the dark, to perform the analysis under yellow light, and to use reference compounds of high purity (57). 

Although simple analytical tests often provide the needed information regarding a water sample, such as the formation and presence of chloroform and other organohaUdes in drinking water, require some very speciali2ed methods of analysis. The separation of trace metals into total and uncomplexed species also requires special sample handling and analysis (12). 

Sample Handling System. Venous or capillary blood, urine, and cerebrospinal fluid are specimens routinely used in medical diagnostic testing. Of these biological fluids, the use of venous blood is by far the most prevalent. Collection devices such as syringes and partial vacuum test tubes, eg, Vacutainer, are used to draw ten milliliters or less of venous blood. At collection time, the test tubes are carefully labeled for later identification. 

The tissue to be analyzed is placed directiy onto the gel. Using the tissue itself and not tissue extracts has advanced the study of proteins that are difficult to extract from tissue, or are damaged by the extraction procedure. Dtif is an important advancement in the area of sample handling and appHcation where direct appHcation of a soHd to a gel matrix may actually enhance resolution. 

Use of remote sampling, handling, and container opening techniques. This can be achieved with robots, or, more commonly, by using... 

LC-GC, therefore, shows promise for forensic science applications, reducing sample handling and preparation steps by essentially using an on-line LC column in place of one or more extraction steps. This is followed by a traditional high resolution GC analysis. The methods described here for pesticides and hormones could be readily adapted to a variety of analyses, especially those involving fatty matrices. Such as tissues, food or blood. 

Procedure. To 100 mL of distilled water, add 5mL of concentrated sulphuric acid, cool and then add 5 g of pure boric acid when this has dissolved cool the mixture in ice. Transfer gradually from a weighing bottle about 0.5 g (accurately weighed) of the sodium peroxide sample (handle with care) to the well-stirred, ice-cold solution. When the addition is complete, transfer the solution to a 250 mL graduated flask, make up to the mark, and then titrate 50 mL portions of the solution with standard 0.02 JVf permanganate solution. 

For greater details on the techniques of LS counting in general, including the specialized nuclear instrumentation required and sample handling and preparation, see Refs 5, 6 7... 

The inherent lability of alkene- and hydroxyalkanesulfonates, variations in isomer composition, and the presence of the disulfonates are features which complicate AOS analyses. Improper sample handling, such as exposure to high temperatures, can also alter active matter composition. Consequently, analytical procedures have been developed that minimize potential sources of error. 

Wotschokowsky, M., Witzenbacher, M., Godau, S. 5th. Int. Symp. on Sample Handling of Environmental and Biol. Samples in Chromatography. Poster Na 36/91, Baden-Baden 1991. 

Nitridoborates of lanthanum and the lanthanides were obtained from reactions of lanthanide metal or lanthanide metal nitride with layer-like (a-)BN at elevated temperatures (3>1200°C). These reactions require elaborated techniques in the inert gas sample-handling and the use of efficient heating sources, such as induction heating. Only some compounds remain stable in this high-temperature segment, and the yields of such reactions are often limited due to the competing stability of binary phases, allowing only the most (thermodynamically) stable compounds to exist. 

An interesting development is the combination of HPLC and on-line measurement of reducing capacity or antioxidative activity. This approach allows both direct identification of antioxidative species in complex foods and quantification of the contribution to the overall antioxidative capacity in the absence of synergistic and antagonistic effects. Major advantages are less sample handling and the ability to rim large series of samples in an automated process. 

Reliable analytical methods are available for determination of many volatile nitrosamines at concentrations of 0.1 to 10 ppb in a variety of environmental and biological samples. Most methods employ distillation, extraction, an optional cleanup step, concentration, and final separation by gas chromatography (GC). Use of the highly specific Thermal Energy Analyzer (TEA) as a GC detector affords simplification of sample handling and cleanup without sacrifice of selectivity or sensitivity. Mass spectrometry (MS) is usually employed to confirm the identity of nitrosamines. Utilization of the mass spectrometer s capability to provide quantitative data affords additional confirmatory evidence and quantitative confirmation should be a required criterion of environmental sample analysis. Artifactual formation of nitrosamines continues to be a problem, especially at low levels (0.1 to 1 ppb), and precautions must be taken, such as addition of sulfamic acid or other nitrosation inhibitors. The efficacy of measures for prevention of artifactual nitrosamine formation should be evaluated in each type of sample examined. 

Lazar, I. M., Karger, B. M., Multiple open-channel electroosmotic pumping system for microfluidic sample handling. Anal. Chem. 74 (2002) 6259-6268. 

TCDD). The majority of these samples have been collected and analyzed at an average cost of 700 per sample. This includes per diem, labor, equipment, expendable supplies, transportation, and 400 per analysis by contract laboratories. An evaluation of this data has suggested that field sampling and sample handling methods have a significant impact upon the precision and accuracy of the resulting data which, in turn, impact the cost and feasibility of various remedial options. 

Field measurements provide savings in sample handling and analysis time, and they eliminate costly delays when re-sampling is required. In addition, they permit important real-time decisions by the on-scene cleanup coordinator regarding removal of sufficient contaminated soil to effect the desired cleanup while avoiding the removal of low-level contamination beyond that required. 

For a detailed discussion of the art of sample handling and data acquisition for blood gas measurements, see National Committee for Clinical Laboratory Standards. Blood gas pre-analytical considerations specimen collection, calibration, and controls Proposed Guideline. NCCLS publication C27-P, Villanova, Pennsylvania, NCCLS, 1985... 

Similar to most Hg sampling methods, sampling sediments and soils require care in avoiding contamination artifacts due to improper sample handling. However, because Hg concentratiorrs are much higher in soUd matrices than in water, if corrrmonly accepted trace-metal protocols are used, substantial contamination artifacts should be exceedingly rare. Also, because sediment Hg concentration profiles... 

Cali JP, and Reed WP (1976) The role of the National Bureau of Standards standard reference materials in accurate trace analysis. In Lafleur PD, ed. Accuracy in Trace Analysis Sampling, Sample Handling, and Analysis, NBS Special Publication 422, Vol i pp 41-63. National Bureau of Standards, Washington, DC. 

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