Sample Handling Solids

The main vessels used for weighing out solids in environmental analyses are weighing bottles, plastic weighing dishes or weighing boats. These containers are used to accurately weigh the solid, using a four-decimal-place balance, and to transfer a soluble solid directly into a volumetric flask. If the solid is not totally soluble it is advisable to transfer the solid to a beaker, add a suitable solvent, e.g. deionized or distilled water, and stir with a clean glass rod until all of the solid has dissolved. It may be necessary to heat the solution to achieve complete 

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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. 

Terms used, methods of sampling, and sample handling will be different for water and submerged solid and semisolid samples. The methods described earlier (i.e., transect and grid sampling) are also applicable to these situations. However, semisolid samples, such as those obtained from lake bottoms, require a special sampler. 

The popularity of this extraction method ebbs and flows as the years go by. SFE is typically used to extract nonpolar to moderately polar analytes from solid samples, especially in the environmental, food safety, and polymer sciences. The sample is placed in a special vessel and a supercritical gas such as CO2 is passed through the sample. The extracted analyte is then collected in solvent or on a sorbent. The advantages of this technique include better diffusivity and low viscosity of supercritical fluids, which allow more selective extractions. One recent application of SFE is the extraction of pesticide residues from honey [27]. In this research, liquid-liquid extraction with hexane/acetone was termed the conventional method. Honey was lyophilized and then mixed with acetone and acetonitrile in the SFE cell. Parameters such as temperature, pressure, and extraction time were optimized. The researchers found that SFE resulted in better precision (less than 6% RSD), less solvent consumption, less sample handling, and a faster extraction than the liquid-liquid method [27]. 

One of the most widely used techniques across all disciplines is solid-phase extraction (SPE). A simple approach to SPE is shown in Fig. 2.3. These columns provide rapid extraction, minimize emulsion problems, and eliminate most sample handling. 

X-ray fluorescence spectrometry was the first non-destructive technique for analysing surfaces and produced some remarkable results. The Water Research Association, UK, has been investigating the application of X-ray fluorescence spectroscopy to solid samples. Some advantages of nondestructive methods are no risk of loss of elements during sample handling operations, the absence of contamination from reagents, etc. and the avoidance of capital outlay on expensive instruments and highly trained staff. 

In addition to a general introduction to surfactants, the book comprises a comprehensive variety of analytical techniques, including sample handling, for the analysis of surfactants in the aquatic environment. Sample preparation includes automated solid phase... 

In the past two decades quite a few new techniques have emerged for the treatment of aqueous samples prior to organic analysis. Perhaps the most important development is that of solid-phase extraction (SPE), which has successfully replaced many off-line steps. This technique can be considered to have introduced a genuine new era in sample handling [1]. The many varieties in which the technique is available and can be applied have made it the key step in handling of aqueous samples. Among the successful varieties are solid-phase microextraction (SPME), matrix solid-phase dispersion, disk extraction and immunosorbent extraction. Several reviews covering these topics have appeared in the literature in the past decade (see e.g. Refs. [2,3] for nonylphenol... 

Performance of sample handling techniques for the extraction of non-ionic surfactants from solid matrices... 

The assembly of large screening libraries for HTS requires the development of archival and retrieval systems that can handle solid compounds and compound solutions in microtubes or in plates in either the 96 or the 384 format. Barcodes are used to identify each sample vial, tube, or plate. Databases record which samples are available, what type of sample it is, and how much is available. All solid samples are prepared first as stock (master) solutions ( around 5 mg/mL in DMSO) in 2-D bar-coded tubes that are then aliquotted to plates and processed as described earlier. The tubes and plates are usually made of polypropylene for compatibility with DMSO. DMSO is the industry standard solvent for screening libraries because many of the archived compounds are not soluble in water at 5 mg/mL. DMSO, an organic solvent, also has a favorable combination of biological... 

IR is one of three forms of vibrational spectroscopy that is in conunon use for process analytical measurements the other two being near-lR (NIR) and Raman. Each one of these techniques has its pros and cons and the ultimate selection is based on a number of factors ranging from sample type, information required, cost and ease of implementation. The sample matrix is often a key deciding factor. NIR has been the method of choice for many years within the pharmaceutical industry, and sample handling has been the issue, especially where solid products are involved. IR is not particularly easy to implement for the continuous monitoring of solid substrates. However, often there is no one correct answer, but often when the full application is taken into account the selection becomes more obvious. In some cases very obvious, such as the selection of IR for trace gas analysis - neither NIR nor Raman is appropriate for such applications. 

T.J. Porro, S.C. Pattacini, Sample handling for mid-infrared spectroscopy. Part I solid and liquid sampling. Spectroscopy, 8(7), 40 7 (1993). 

Safe handling of laboratory glassware Safety showers and eye washes Technique of solid sample handling for IR spectroscopy... 

Diffuse-reflectance MIRS has found a number of applications for dealing with hard-to-handle solid samples, such as polymer films, fibers, or solid dosage forms. Reflectance MIR spectra are not identical to the corresponding absorption spectra, but sufficiently close in general appearance to provide the same level of information. Reflectance spectra can be used for both qualitative and quantitative analysis. Basically, reflection of radiation may be of four types specular, diffuse, internal, and attenuated total. 

There are several techniques for handling solid samples. The "best" technique again depends on the particular application one has, If there is a suitable solvent, one can dissolve the solid... 

The tissue to be analyzed is placed directly 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 application where direct application of a solid to a gel matrix may actually enhance resolution. 

Supercritical fluid extraction (SFE) has been demonstrated as a technique that has eliminated some of the tedious steps of current liquid-liquid and solid-liquid extraction procedures. SFE also offers cleaner extracts, less sample handling and equivalent or better recoveries to conventional technologies. As a technique, it is cost effective, time efficient and low in solvent waste generation. 

A list of the 64 analytes and their method performance is shown in Table 6.6. The increased number of analytes is possible because of improvements to the collision region of the MS/MS system that provide increased sensitivity and reduced memory effects. In addition, robotic systems for sample handling and on-line solid-phase extraction (SPE) of plasma samples were integrated with the LC/MS/MS system (Figure 6.22). An isocratic reversed-phase HPLC method provided a cycle time of 4.5 min per sample. The on-line sample preparation and short analysis resulted in an increased sample throughput that required less time from the scientist. The... 

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