Cuvette material

1 Cuvette Material. An ideal tube material must be chemically inert, have good thermal and electrical conductivity, be obtained in a state of high purity (Table 9), be machined easily, and have low porosity, a low expansion 

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Cuvette material Optically clean glass Electrode cell material Organic glass... 

As a result, cuvettes for Raman spectroscopy should be carefully selected. They may, due to their impurities, add a background to the spectrum of the sample. In addition, all cuvette materials produce their own Raman spectra, which have to be considered, when the Raman spectra of the sample are evaluated. Fig. 3.5-17 a shows a Raman spectrum of a typical optical glass BK7, Fig. 3.5-17 b that of quartz glass suprasil, and Fig. 3.5-17 c of sapphire. Suprasil is a synthetic quartz which does not normally contain impurities. Therefore, Suprasil of ESR quality is highly recommended as Raman cuvette material. Also, sapphire is a good cuvette material, as it is very hard, inert, has a good thermal conductance, and shows only weak but sharp Raman lines (Porto and Krishnan, 1967). It is used for the production of the universal Raman cell (Schrader, 1987). The sharp Raman lines of sapphire observed in the spectra of the sample may be subtracted from the spectrum or used as internal standard for quantitative analyses (Mattioli et al, 1991). 

Background emission caused by transition metals in the cuvette material is eliminated by employing cuvettes made of suprasil. 

The cuvette material should be resistant to the action of chemicals. The cuvettes are placed in measuring chambers in special holders that provide accurate and reproducible location of the sample in the path of the radiation beam. 

TABLE 4.1 Wavelength Ranges Compatible with Some Cuvette Materials... 

It is very important to make the right choice of the cuvette material for liquid and gas samples. This material must be transparent to the infrared light. Sodium chloride is the most often used material for the cuvettes and the optics of the infrared spectrometer. Other material such as special types of glass, quartz, aluminum oxide, calcium chloride, potassium bromide and so on are also used for special purposes. 

For the analysis of liquid samples, the cuvette material must chosen so that the sample is physically and chemically inert to this material. 

The mechanism by which free atoms are produced in the graphite furnace depends on a number of factors, such as the compounds still present in the cuvette at the atomization temperature, the cuvette material, the atmosphere inside the cuvette, the heating rate of the cuvette, and the temperature of operation of the cuvette. 

Atomization. Atomization in the graphite furnace can emanate from either molecules or atoms depending on the nature of the sample and behaviour of the analyte. If atomization emanates from molecules, it can be a thermal decomposition or dissociation of a compound, or the reduction of a metal oxide on the hot graphite surface. The difference between these two mechanisms is the active participation of the cuvette material (carbon) in the dissociation of the sample molecules. If atomization emanates from the metal, it can be classified either as desorption or volatilization. 

Choose cuvette material (generally glass but cheap even scratched cuvettes may not degrade signals). 

It seems that deep-seated cleavage of the dioxin nucleus must accompany dechlorination in methanol. When pure dibenzo-p-dioxin (II) was irradiated in cyclohexane solution in a quartz cuvette, it darkened in color, and a precipitate of intractable dark brown material was collected and was insoluble in the common solvents except for methanol. 

Fig. 2.14 The scheme of the cylindrical lens method for diffusion coefficient measurement (1) the source with the horizontal slit (2) the condenser supplying a handle of parallel beams (3) the cuvette with a refraction index gradient where the beams are deflected (4) the objective lens focusing the parallel beams to a single point (5) the optical member with an oblique slit and a cylindrical lens (6) the photosensitive material...

Background is measured without the sample - but including the sample holder and all kind of wrapping that does not belong to the material of interest (e.g., aluminum foil, empty cuvette, or cuvette with solvent, respectively). 

What material is the sample tube made of Just like a cuvette in a UV-visible spectrometer has to be optically transparent, the EPR sample tube must be transparent for the magnetic component of microwaves. High-quality quartz is the preferred construction material low-quality quartz and especially any type of glass will not... 

Material required For total protein extract and enzyme activities extraction buffer 50 mM potassium phosphate, pH 7.0,1 mM EDTA, 1% of PVP (100 mg/mL), for CAT, GR, and SOD and with 10 mM ascorbato for APX activity. Bio-Rad protein assay, centrifuge, spectrophotomer and quartz cuvette. 

Materials required Sample solution in methanol, distilled water, 20% Na2C03, Folin-Ciocalteu s phenol reagent, water bath, graduated tube, cuvette, micro pipette (0.1 ml), pipette of 1,2 and 10 ml, test tubes of 20 ml, pure ferulic acid (Serva, Germany), Shimadzu UV 160 spectrophotometer. 

Material required Feat tissue, dimethyl sulphoxide, vial, graduated tube, cuvette, thermostat, pipette of 1,2 and 10 ml, Shimadzu UV160 spectrophotometer. 

Cuvettes used for UV-VIS spectrophotometry must be transparent to all wavelengths of light for which it is used. If visible light is used, the material must ideally be completely clear and colorless, which means that inexpensive materials, such as colorless plastic and ordinary colorless glass, are perfectly suitable. A case of 500 plastic 1-cm-square cuvettes may cost as little as 50. However, ordinary colorless glass and plastic are not transparent to light in the ultraviolet region. For ultraviolet spectrophotometry, the cuvettes must be made of quartz, which is more expensive. A matched set of two cuvettes to be used in a doublebeam spectrophotometer may cost as much as 400. 

Standard reference material (SRM) for wavelength accuracy, stray light, resolution check, and photometric accuracy can be purchased from NIST. Certified reference materials (CRMs) which are traceable to NIST and recertification services can be purchased from instrument manufacturers and commercial vendors [12]. The cost of neutral-density filters and prefabricated standard solutions in sealed cuvettes can be substantial. When purchasing performance verification standards from a secondary supplier other than a national standard organizations such as NIST in the United States and National Physical Laboratory (NPL) in the United Kingdom, make sure that the traceability of the standards are available in the certificates. The traceability establishes the relationship of individual results to the national standard through an unbroken chain of comparisons. 

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