This is done by reading the spectra produced when the sample is excited by radiation. The atoms absorb ultraviolet or visible light and make transitions to higher energy levels. The concentration is usually determined from a calibration curve, obtained using standards of known concentration. AAS is a technique used mostly for determining the concentration of a particular metal element within a sample. A common method is to introduce a liquid sample into a flame.
These along with the similar problems associated with homogenous catalysts make a heterogeneous variant more favourable.  These problems were found to mitigated by placing the metaloporphyrin in a MOF. Work was done by Brown et al. to place manganese porphyrins within a zirconium MOF. It was found that there was minimal deactivation of the catalyst while the activity of the catalyst remained high.
The implication of this is that Sulphur is stable in the presence of water and in acidic conditions free from oxidizing agents. In alkaline conditions, it is unstable and tends to disproportionate to give HS–, S2– (and polysulfides), SO42−, and other oxidation products. In industrial applications, these reactions are slow and take place only in hot and very alkaline media. Sulphur is usually a major product of sulphur mineral oxidation at pH of 4.6. Increase in pH to 9 accompanied by an increase in potential results in the formation of sulphate ions (Hamilton and Woods, 1981).
Introduction: High Performance Liquid Chromatography or also known as High Performance Liquid Chromatography is one of the most powerful and most commonly used analytical separation technique. HPLC is a form of liquid chromatography that separated solutes/compounds dissolved in the solution (High-performance liquid chromatography, 2012). It is an improved form of column chromatography, where the solvent is passed through under high pressure instead of letting it drip down due to gravity. The sample is injected into the column to separate the sample of interest. The two different phases in HPLC are mobile and stationary phase.
The hydrothermal technique usually gives hydroxyapatite powders a high degree of crystallinity. However, need high temperature and the obtained powders are usually in agglomeration and the size distribution are usually in wide range. The main advantage of emulsion technique is the simplicity of the process, good crystallinity product without high temperature, and favours the formation of small crystallites with a sufficient narrow size distribution. Sol-gel synthesis of hydroxyapatite has many advantages, which include high product purity, homogeneous composition, and low synthesis temperature. When the mass production of high crystalline hydroxyapatite is required, mechanochemical treatment is more suitable.
2. Oxidation of alkenes and their derivatives in aqueous media The oxidation of carbon–carbon double bonds by permanganate ion is an important and well-known reaction in organic chemistry, in a mechanistic as well as a synthetic prospective. Under alkaline conditions, olefins are converted into the corresponding diols in good yield,3,4 while in neutral or slightly basic solutions a-hydroxy ketones are produced.4,5 These reactions are always accompanied by a certain amount of C–C bond cleavage6 and, under acidic conditions, the cleavage products predominate.7,8 Aqueous potassium permanganate was used originally for
Fiber SPME is a new sample preparation technique using a fused-silica fiber coated on the outside with an appropriate stationary phase. In-tube SPME is suitable for automation, and extraction, desorption and injection can be done continuously using a standard autosampler. Drawing and ejection of the sample solution, switching of the valves, control of peripheral equipment such as the HPLC and MSD, and analytical data processing are all computer controlled. (9) Application SPME is widely applied in pharmaceutical analysis. The types of compounds that can be analysed by SPME range from non-polar to semi-polar materials due to the different sorbent materials available.
Table 2 Advantages and disadvantages of different types of heat pumps Type of Heat Pump Advantages Disadvantages Vapor Recompression Proven technology with very good performance Simpler process (when compared to traditional compression) Recycle of produced vapour within the system (no need for external working fluid) Low operating cost Ease of design and operation Potential for high investment cost (although this is largely dependent on design) Potentially long payback times (unacceptable for industry deployment) Use of high grade energy (electricity / mechanical work) Possibility of leakage is a concern Vapour Compression Proven at industrial scale (mature technology) No major modifications to processes with implementation Useful with corrosive and fouling components Option to drive with mechanical energy or electrical energy Acceptable efficiencies (up to 60% of Carnot’s limit) Design dependent on the ability of the heat exchange fluid to meet stringent operational, environmental and safety
Introduction Fluorescents are a large family of light sources. There are three main types of fluorescent lamps: cold cathode, hot cathode, and electroluminescent. They all use phosphors excited by electrons to create light. A fluorescent lamp or a fluorescent tube is a low pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow.
It is based on the fact that vibration and rotation of the atoms inside a molecule has discrete energy levels. Infrared spectrum is a molecular vibrational spectrum. If light passes through the material some of the light will be absorbed that matches the exact frequency. Using a light source, an optical apparatus, an interferometer and detector, we are able to measure the absorbance and transmittance of infra-red light in the substance. Molecular spectroscopy (also called FTIR –(Fourier Transform Infra Red spectroscopy) has advantages in many fields like Medicine to detect Cancer, Pollution control and detection of poisons, and used in chemistry for process control and molecular analysis.