Advantages And Disadvantages Of Raman Spectroscopy

This experiment was used to measure the buildup of the colored product, benzoquinone, to observe the change in the absorbance of the mixture in a spectrophotometer at a wavelength of 486 nm. It was hypothesized that over a longer period catechol oxidase activity and reaction in the mixture will continue, creating more benzoquinone resulting in an increase in the absorbance. The hypothesis was supported by the data as seen in figure 2 which shows the positive relationship between time and absorbance. As can be seen, with more time the catechol oxidase can catalyze the reaction and turn catechol (substrate) into benzoquinone (product). This in turn increased absorbance of the blue light at 486 nm by the solution containing benzoquinone which has a dark brown

In experiment two, the drug Panacetin was separated by a series of chemical reactions into its three components: sucrose, aspirin, and an unknown active ingredient, either acetanilide or phenacetin. The purpose of this lab was to determine what percentages of each component is present in the pain-killer. The initial step was to dissolve Panacetin in dichloromethane. However, sucrose is insoluble in dichloromethane because organic molecules are soluble in organic solvents, and dichloromethane is an inorganic solvent, so only aspirin and the unknown dissolved. By using gravity filtration, sucrose was filtered from the solution and 0.30g of solid was collected.

Different procedures were used to isolate benzil from the ether layer and benzoic acid from the aqueous layers. To isolate benzil, anhydrous MgSO4 was added to the flask containing the ether layer solution. MgSO4 removes the remaining water in the ether layer solution. After making sure that enough amount of MgSO4 present in the solution, the ether solution was filtered by using gravity filtration. During filtration, MgSO4 was removed from the solution and the ether solution was collected in 25 ml flask. To separate benzil from the filtered ether solution, the beaker containing the ether solution was heated until the ether evaporated. After letting the beaker to cool to room temperature, the mass of the beaker with the benzil crystals was measured. From the combined mass of the beaker and the benzil crystals and from the predetermined mass of the beaker, the mass of the collected crystals was calculated to be 0.266 gram.

The purpose of experiment three was to identify the unknown component in the drug Panacetin. The use of physical properties can help identify unknown compounds and estimate the degree of their purities. In this experiment, solubility in boiling water and melting point were used to determine if the unknown was acetanilide or phenacetin. Since both compounds are soluble in boiling water and insoluble in cold water, recrystallization was used to remove any impurities from the solid.

Spectroscopy is the study of light. A spectrophotometer is a machine used to determine the absorbance of light at any given wavelength. It does this by using a source of white light through a prism, which gives multiple wavelengths that can be individually focused (Ayyagari and Nigam, 2007). Substances are put into cuvettes that are glass or quartz containers that light can easily travel through. The light that is being focused travels through the substance gets absorbed by the

The regulation of contents in beverages is important for the health and safety of the public. The chemicals caffeine and benzoic acid are common additives to beverages for the stimulation effect and as a preservative, respectively. To simultaneously determine the amount of each of these chemicals, a method combining UV/Visible spectroscopy and reversed-phase high performance liquid chromatography was introduced. The experimentally determined concentrations at the 95% confidence interval of caffeine and benzoic acid in Mountain Dew were 149 +/- 5 ppm and 308 +/- 6 ppm, respectively. The method showed separation of

The isosbestic point of the acid (pH6) and basic forms (pH10) of para Nitrophenol (PNP) was expected at 350nm. As you can see in figure 2, the graph shows the intersection of 2 curves at ~350nm, which is matched with the literature value. Also, the pKa of PNP was expected 7.15 at room temperature. Refer to figure 3, the pKa is estimated to be 7.15-7.2, which very close to the literature value. In addition, the lab was succeeded in illustrating the use of a spectrophotometry to analyze concentrations of chemical substance. The absorbances of 2 unknowns were felt on the standard curve as the expectation (refer to table 4). The minimum absorbance of the known standards was 0.193 and the maximum is 1.830. The absorbance of the unknown

Pre-Lab: Analgesic drugs are known for reducing pain, while antiseptic drugs reduce symptoms such as fevers and swelling. However, some of these drugs can reduce both illnesses. To obtain a pure compound in these drugs, the scientist needs to separate the desired compound by taking advantage of the different physical and chemical properties. Such as; different boiling points, melting points and their solubility properties. To do this a chemist can also asses the differences between acidic and basic substances when they are added to water soluble mixtures. Within this current experiment I will asses the

The goal of this experiment is to prepare a photosensitive solution and explore its properties. While analyzing the solution, one will learn how to successfully handle these sensitive chemicals and then establish its properties via spectrophotometry.

AAS has contributed to the understanding of elements having different absorption emission spectra due to their difference in energy levels. In the absorption spectrum, the absorbed light are shown as black gaps. As the number of electrons increase, the number of spectral lines also increase. Hence, by measuring the absorption of light, the concentration of the element within a sample can be determined. By knowing the concentrations of an element, scientists are now aware that even the smallest amount can make a significant impact towards the biological system. Therefore, scientists have brainstormed ways to monitor the use of chemicals in the

First, dichloromethane was the least polar solvent, so it barely moved up the plate. Hence, the spots on the TLC plate stayed at almost the same place they were spotted on, and separation did not occur. As a result, the retention factor (Rf) values for these components were too small. In addition, the second solvent, methanol, was the most polar solvent out of the three, and the solvent moved up the plate too quickly. This resulted in the components moving up the plate based on the solvent's polarity instead of their own, and a smear of all components at the solvent front was observed. Hence, the Rf values could not be determined. Lastly, ethyl acetate, a moderately polar solvent, moved up the plate with moderate speed. This gave the components time to move up the plate according to their polarity, and the Rf values could be used to identify the unknown compound. According to the TLC method with ethyl acetate solvent, the unknown compound had the same Rf value with acetanilide (Rf = 0.40). As a result, the unknown compound was identified as

• Molecules with small differences in absorption wavelengths can be detected well due to their differences in separation time. i.e one which travels faster is measured prior to the other which is measured later. This is the prime advantages if HPLC which makes it

Howlett, S. E. and Steiner, R. R. 2011. Validation of Thin Layer Chromatography with AccuTOF-DART™ Detection for Forensic Drug Analysis*. Forensic Sciences [e-journal] 56 (5), pp. 1261--1267. Available through: Anglia Ruskin University Library website http://libweb.anglia.ac.uk [Accessed on 11 March 2014].

The purpose of this experiment was to determine the pKa of the bromothymol blue (indicator) through absorption spectroscopy. Bromothymol blue being a monoprotic acid base indicator, displays different colors at different pH because of the differences in the ratio of the conjugated acid and base form. The fraction of conjugate acid and base was interpolated for the solutions through the acquired absorbance spectrum of the bromothymol blue at various pH. The rearranged form of Henderson Hasselbalch equation was graphed as a function of pH to determine the pKa of the indicator.

Recently, new drugs have appeared in the illegal drug market. The new substances claimed to contain “non-Illegal” compounds yet still deliver the psychoactive effects desired. This new class of compounds are now commonly known as “SmartDrugs” and are distributed through internet commerce or “Smart Shops”. Some of the drugs included in the mixtures are cathinones and trytamine analogs of psylocin. The current method of identification is toxicological screening and is proven to have some ineffectiveness at identifying the new compounds. However, new advances in mass spectrometry are expected to broaden the diagnostic spectrum of the toxicological screening, capable of detecting hundreds of compounds at nanomolar levels. New liquid phase separation techniques are coupled with the mass spectrometry for high accuracy at identification (Favretto, 2013).