For photometric measurements of liquid solutions, samples in a predefined format should be placed in the optical light path of a photometer. The default option for this application is buckets, sample containers with 2 or 4 optical transparent windows. This baking material is ideal for use in the visible spectral range and has a decent transmission range of 340 to 2,500 nm. Most applications will fall into the range and many experiments do not need the additional UV range (190 – 340 nm) available with quartz materials.
Buckets are small rectangular containers made of glass or quartz. They are usually designed with a path length of 10 mm for the light beam through the solvents, but the length of the pad can be extended from 0.2 or 0.5 mm to 100 mm. The sample cell contains a diluted solution of the solvents to be tested. By now, it should be clear that each of the available baking variants is superior in some way. Before selecting one, the precise purpose and equipment should be specified. Although plastic is not ideal for UV range study, it is an economical solution for all experiments with visible light range.
Of course, the solution can concentrate the samples, but it is usually difficult in situations where the sample evaporates or undergoes a chemical change during the concentration process. If the wavelengths in the UV range, below about 300 nm, quartz cells or a special type of plastic are to be used, which provide sufficient transparency in this range. Most experiments with emission absorption spectroscopy question samples that are gases, liquids or solutions. The exception to this are fixed samples that can be mounted on the spectrometer. Gas spectroscopy experiments are usually conducted with long-term cells that are sealed off or through which gas flows. For liquids and solutions, buckets are the most common sample containers.
Buckets made of acrylic plastic or ordinary glass are already absorbed at higher wavelengths. In addition, many of the plastic buckets are not compatible with most organic solvents. If you use a quartz tamper, keep in mind that it is very expensive (~$150 each). If you break it, you’ll have to pay for it, because your lab equipment costs won’t cover these types of losses. The article examines the optical characteristics of such materials that will help you make the right decision before proceeding with absorption measurements.
The selection of the bucket is an important element in measuring absorption in the UV-Vis spectrophotometer, as the solutions for analysis are placed in the bucket. In addition, selection is a delicate task because there are several buckets available. Next, it is discussed how different factors influence the selection of the bucket in the UV-Vis spectroscopy system. The next important aspect concerns the measuring wavelengths involved in the application in question. Standard buckets made of PMMA, polystyrene or ordinary glass are only transparent in the visible range. If wavelengths are used in the UV range, below about 300 nm, buckets of quartz glass or a special type of plastic should be used, which provide sufficient transparency in this range.
If the bucket is not properly veiled, the absorption sensitivity to the measurement may be reduced. Knowing the experimental conditions during measurements is important. Buckets designed for a path length of 1 cm are standard and are the most common.
These buckets are made of Far UV Quartz with a spectral range of 170 to 2700 nm. A bucket for spectrophotometric measurements is a small, transparent rectangular vessel that is available in a variety of materials, quality levels and dimensions. Glass buckets are used for measurements in the visible range of 320 to 2500 nm. Quartz semimers deliver accurate results over the UV and visible range from 200 to 2500 nm. The lower the production tolerance, the better and more repeatable the measurement. Traditional ultraviolet-visible spectroscopy or fluorescence spectroscopy uses liquid samples.
Air can also be seen as a filter because wavelengths of light shorter than about 200 nm are absorbed by molecular oxygen in the air. A special and more expensive configuration is required for measurements with wavelengths of less than 200 nm, usually involving an optical system filled with pure argon gas. Bucket-free systems are also available that allow the analysis of very small sample volumes, for example in DNA or RNA analysis. Glass buckets are usually intended for use in the wavelength range of visible light, while molten quartz is usually used for ultraviolet applications. Absorption studies have become a basis for the investigation of numerous particles and solutions. For this to happen, the light must be transmitted in a defined format.
Acid and alkali are avoided due to their corrosive effects on glass, and acetone is not suitable when working with plastic buckets. If the solution is transferred to a bucket using a Pasteur pipette containing Cuvettes air, bubbles can form in the bucket, reducing the purity of a solution and scattering the light rays. The solution in the bucket should be high enough to be in the path of the light source.