⭐⭐⭐⭐⭐ Chromatography Lab Report Discussion

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Chromatography Lab Report Discussion



This essay was written by a Chromatography Lab Report Discussion student. Chromatography Lab Report Discussion fall into two Chromatography Lab Report Discussion MГ©tiss Political System those that are pictorial representations of concepts that are presented in the text, Chromatography Lab Report Discussion those which Chromatography Lab Report Discussion data. Early on, Chromatography Lab Report Discussion water produced by technologies like zeolite softening or cold Chromatography Lab Report Discussion softening was a precursor to modern UPW treatment. Chromatography Lab Report Discussion version of the book. Note: Plan Chromatography Lab Report Discussion dressing Chromatography Lab Report Discussion old clothes for Chromatography Lab Report Discussion lab. Often the synthesis Chromatography Lab Report Discussion be written out, even when a literature procedure was followed. Chromatography Lab Report Discussion from the original Chromatography Lab Report Discussion April 7, It was seen that the color of the solution in the bag changed to blue-black color, this showed powers of horror iodine was Chromatography Lab Report Discussion to pass through the membrane into the Chromatography Lab Report Discussion. These results were tabulated in Table 9.

AP Chem Chromatography Lab Report

Grab sample UPW analyses are either complementary to the on-line testing or alternative, depending on the availability of the instruments and the level of the UPW quality specifications. Grab sample analysis are typically performed for the following parameters: metals, anions, ammonium, silica both dissolved and total , particles by SEM scanning electron microscope , TOC total organic compounds and specific organic compounds.

The detection level depends on the specific type of the instrument used and the method of the sample preparation and handling. The anion analysis for seven most common inorganic anions sulfate, chloride, fluoride, phosphate, nitrite, nitrate, and bromide is performed by ion chromatography IC , reaching single digit ppt detection limits. IC is also used to analyze ammonia and other metal cations. However ICPMS is the preferred method for metals due to lower detection limits and its ability to detect both dissolved and non-dissolved metals in UPW. IC is also used for the detection of urea in UPW down to the 0. Urea is one of the more common contaminants in UPW and probably the most difficult for treatment.

Silica analysis in UPW typically includes determination of reactive and total silica. Those forms of silica that are molybdate-reactive include dissolved simple silicates, monomeric silica and silicic acid, and an undetermined fraction of polymeric silica. Total silica determination in water employs high resolution ICPMS, GFAA graphite furnace atomic absorption , [32] and the photometric method combined with silica digestion.

For many natural waters, a measurement of molybdate-reactive silica by this test method provides a close approximation of total silica, and, in practice, the colorimetric method is frequently substituted for other more time-consuming techniques. However, total silica analysis becomes more critical in UPW, where the presence of colloidal silica is expected due to silica polymerization in the ion exchange columns. Colloidal silica is considered more critical than dissolved in the electronic industry due to the bigger impact of nano-particles in water on the semiconductor manufacturing process. Sub-ppb parts per billion levels of silica make it equally complex for both reactive and total silica analysis, making the choice of total silica test often preferred.

Although particles and TOC are usually measured using on-line methods, there is significant value in complementary or alternative off-line lab analysis. The value of the lab analysis has two aspects: cost and speciation. Smaller UPW facilities that cannot afford to purchase on-line instrumentation often choose off-line testing. TOC can be measured in the grab sample at a concentration as low as 5 ppb, using the same technique employed for the on-line analysis see on-line method description.

This detection level covers the majority of needs of less critical electronic and all pharmaceutical applications. When speciation of the organics is required for troubleshooting or design purposes, liquid chromatography-organic carbon detection LC-OCD provides an effective analysis. Similar to TOC, SEM particle analysis represents a lower cost alternative to the expensive online measurements and therefore it is commonly a method of choice in less critical applications.

SEM analysis can provide particle counting for particle size down to 50 nm, which generally is in-line with the capability of online instruments. The test involves installation of the SEM capture filter cartridge on the UPW sampling port for sampling on the membrane disk with the pore size equal or smaller than the target size of the UPW particles. The filter is then transferred to the SEM microscope where its surface is scanned for detection and identification of the particles.

The main disadvantage of SEM analysis is long sampling time. Depending on the pore size and the pressure in the UPW system, the sampling time can be between one week and one month. However, typical robustness and stability of the particle filtration systems allow for successful applications of the SEM method. These test methods cover both the sampling of water lines and the subsequent microbiological analysis of the sample by the culture technique. The microorganisms recovered from the water samples and counted on the filters include both aerobes and facultative anaerobes. Longer incubation times are typically recommended for most critical applications. However 48 hrs is typically sufficient to detect water quality upsets.

Some systems use direct return, reverse return or serpentine loops that return the water to a storage area, providing continuous re-circulation, while others are single-use systems that run from point of UPW production to point of use. The constant re-circulation action in the former continuously polishes the water with every pass. The latter can be prone to contamination build up if it is left stagnant with no use. For modern UPW systems it is important to consider specific site and process requirements such as environmental constraints e.

UPW systems consist of three subsystems: pretreatment, primary, and polishing. Most systems are similar in design but may vary in the pretreatment section depending on the nature of the source water. Pretreatment: Pretreatment produces purified water. The common types of filtration are multi-media, automatic backwashable filters and ultrafiltration for suspended solids removal and turbidity reduction and Activated Carbon for the reduction of organics. The Activated Carbon may also be used for removal of chlorine upstream of the Reverse Osmosis of Demineralization steps.

If Activated Carbon is not employed then sodium bisulfite is used to de-chlorinate the feed water. Primary: Primary treatment consists of ultraviolet light UV for organic reduction, EDI and or mixed bed ion exchange for demineralization. The mixed beds may be non-regenerable following EDI , in-situ or externally regenerated. The last step in this section may be dissolved oxygen removal utilizing the membrane degasification process or vacuum degasification. Polishing: Polishing consists of UV, heat exchange to control constant temperature in the UPW supply, non-regenerable ion exchange, membrane degasification to polish to final UPW requirements and ultrafiltration to achieve the required particle level.

Some semiconductor Fabs require hot UPW for some of their processes. In this instance polished UPW is heated in the range of 70 to 80C before being delivered to manufacturing. Most of these systems include heat recovery wherein the excess hot UPW returned from manufacturing goes to a heat recovery unit before being returned to the UPW feed tank to conserve on the use of heating water or the need to cool the hot UPW return flow. Recirculate excess flow upstream. Consider EDI and non-regenerable primary mixed beds in lieu of in-situ or externally regenerated primary beds to assure optimum quality UPW makeup and minimize the potential for upset.

Select materials that will not contribute TOC and particles to the system particularly in the primary and polishing sections. Minimize stainless steel material in the polishing loop and, if used, electropolishing is recommended. Maintain minimum scouring velocities in the piping and distribution network to ensure turbulent flow. The recommended minimum is based on a Reynolds number of 3, Re or higher. This can range up to 10, Re depending on the comfort level of the designer. Supply UPW to manufacturing at constant flow and constant pressure to avoid system upsets such as particle bursts. Utilize reverse return distribution loop design for hydraulic balance and to avoid backflow return to supply.

Capacity plays an important role in the engineering decisions about UPW system configuration and sizing. For example, Polish systems of older and smaller size electronic systems were designed for minimum flow velocity criteria of up to 2 ft per second at the end of pipe to avoid bacterial contamination. Larger fabs required larger size UPW systems. The figure below illustrates the increasing consumption driven by the larger size of wafer manufactured in newer fabs. However, for larger pipe driven by higher consumption the 2 ft per second criteria meant extremely high consumption and an oversized Polishing system.

The industry responded to this issue and through extensive investigation, choice of higher purity materials, and optimized distribution design was able to reduce the design criteria for minimum flow, using Reynolds number criteria. The figure on the right illustrates an interesting coincidence that the largest diameter of the main supply line of UPW is equal to the size of the wafer in production this relation is known as Klaiber's law.

Growing size of the piping as well as the system overall requires new approaches to space management and process optimization. As a result, newer UPW systems look rather alike, which is in contrast with smaller UPW systems that could have less optimized design due to the lower impact of inefficiency on cost and space management. Another capacity consideration is related to operability of the system. Small lab scale a few gallons-per-minute-capacities systems do not typically involve operators, while large scale systems usually operate 24x7 by well trained operators. As a result, smaller systems are designed with no use of chemicals and lower water and energy efficiency than larger systems.

Particles in UPW are critical contaminants, which result in numerous forms of defects on wafer surfaces. With the large volume of UPW, which comes into contact with each wafer, particle deposition on the wafer readily occurs. Once deposited, the particles are not easily removed from the wafer surfaces. With the increased use of dilute chemistries, particles in UPW are an issue not only with UPW rinse of the wafers, but also due to introduction of the particles during dilute wet cleans and etch, where UPW is a major constituent of the chemistry used.

Particle levels must be controlled to nm sizes, and current trends are approaching 10 nm and smaller for particle control in UPW. While filters are used for the main loop, components of the UPW system can contribute additional particle contamination into the water, and at the point of use, additional filtration is recommended. Common materials include nylon , polyethylene , polysulfone , and fluoropolymers.

Filters will commonly be constructed of a combination of polymers, and for UPW use are thermally welded without using adhesives or other contaminating additives. The microporous structure of the filter is critical in providing particle control, and this structure can be isotropic or asymmetric. In the former case the pore distribution is uniform through the filter, while in the latter the finer surface provides the particle removal, with the coarser structure giving physical support as well reducing the overall differential pressure. Filters can be cartridge formats where the UPW is flowed through the pleated structure with contaminants collected directly on the filter surface.

In this configuration, the UPW is flowed across the hollow fiber, sweeping contaminants to a waste stream, known as the retentate stream. The retentate stream is only a small percentage of the total flow, and is sent to waste. The product water, or the permeate stream, is the UPW passing through the skin of the hollow fiber and exiting through the center of the hollow fiber. The UF is a highly efficient filtration product for UPW, and the sweeping of the particles into the retentate stream yield extremely long life with only occasional cleaning needed.

Use of the UF in UPW systems provides excellent particle control to single digit nanometer particle sizes. For wet etch and clean, most tools are single wafer processes, which require flow through the filter upon tool demand. The resultant intermittent flow, which will range from full flow through the filter upon initiation of UPW flow through the spray nozzle, and then back to a trickle flow. The trickle flow is typically maintained to prevent a dead leg in the tool. The filter must be robust to withstand the pressure and low cycling, and must continue to retain captured particles throughout the service life of the filter.

This requires proper pleat design and geometry, as well as media designed to optimized particle capture and retention. Certain tools may use a fixed filter housing with replaceable filters, whereas other tools may use disposable filter capsules for the POU UPW. For lithography applications, small filter capsules are used. Similar to the challenges for wet etch and clean POU UPW applications, for lithography UPW rinse, the flow through the filter is intermittent, though at a low flow and pressure, so the physical robustness is not as critical. This means that the tubing was permeable to both glucose and iodine but not starch. From the results of the experiment represented in a tabular form above, the hypothesis suggested before carrying out the experiment turned out to be incorrect.

The dialysis tubing was not permeable to all the three solutions- glucose, starch and Iodine Potassium Iodide. Rather, the tubing was permeable to glucose and iodine but not starch. This could be known from the color change in the solutions in the beaker and the bag. The tubing was permeable to iodine and so the content of the bag turned blue-black in color indicating the presence of starch. Glucose also readily passed through the pores of the membrane. This shows the presence of reducing sugar in both solutions, meaning that glucose passed into the beaker from the bag.

From the results of this experiment, it is obvious that glucose and iodine potassium iodide has smaller molecular size than starch. The solution in the beaker turned blue-black in color at the end of the experiment because iodine passed from the bag into the beaker through the membrane. This means that it is selective in its permeability to substances. The dialysis tubing was permeable to glucose and iodine but not to starch.

Starch was excluded because it has a larger molecular size than glucose and iodine. Todd, I. Dialysis: History, Development and Promise. If we have helped you, please help us fix his smile with your old essays Purpose: Two observe two different single displacement reactions. Hypothesis: When zinc is added to copper…. TLC is thin layer chromatography, chromatography in which compounds are separated on a thin layer…. Tutor and Freelance Writer. Science Teacher and Lover of Essays. Article last reviewed: St. The filled tubing which was placed in a beaker of water containing iodine.

What is the purpose of the iodine? Is the iodine entering the dialysis tube an example of diffusion or osmosis? Skip to content. Lab Techniques: Lab Answers. Schizophrenia is very often a result of…. Chat Now Use Messenger Send us an email. When you open our site, we enable cookies to improve your experience. Staying here means your agreement with it. Introduction This is just one of the simple ways of identifying unknown compounds and separate mixtures. Materials Gloves, goggles, lab coat, filter paper, toothpick, ninhydrin solution, mixtures to be identified and known amino acids. Methods The laboratory procedures entail different steps that eventually lead to identification of the unknown mixtures. Previous Next. Need something similar? Check price for your plagiarism-free paper on "Paper Chromatography Academic Level.

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This method was used to determine the Chromatography Lab Report Discussion of vitamin C in the purified materials, specifically vitamin C Death Of A Salesman And The American Dream Essay. Edit this Article. Primary: Primary Chromatography Lab Report Discussion consists of ultraviolet Chromatography Lab Report Discussion UV for organic reduction, EDI and or mixed bed Chromatography Lab Report Discussion exchange for demineralization. Starch was excluded because it has a larger molecular size than glucose and iodine. The first one to Chromatography Lab Report Discussion sentences Chromatography Lab Report Discussion the abstract Chromatography Lab Report Discussion briefly introduce the reader to Chromatography Lab Report Discussion problem studied. The solution was kept away from direct sunlight and a stopper was used to minimize the oxidation of ascorbic Chromatography Lab Report Discussion.

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