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Experiment gas chromatography thesis
Gas chromatography essay
Experiment gas chromatography thesis
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Drugs are used everyday by people in many different ways for many different reasons. Drug testing has become a standard in pre-employment testing, because of the wide variety of drug use in today's society. Drugs tested for by a possible employer include Cocaine (crack), Amphetamines (crystal), Opiates (codeine, morphine, heroin), PCP (phencyclidine), and Marijuana. Gas chromatography/mass spectrometry is used to test hair and urine samples of possible drug abusers or job applicants, and it is the best method for the testing of drug use. Gas chromatography and mass spectrometry are two different methods for identifying chemical substances, and the two instruments have be coupled together to perform a highly complementary analytical function. The gas chromatograph and the mass spectrometer have theories behind how their techniques work, and specific forensic applications for their instrumentation.
The history and theory of the gas chromatography started over forty years ago with the invention of the capillary column. The gas chromatograph offers rapid and very high-resolution separations of a very wide range of compounds, with the only restriction that the analyzed substance needs to have sufficient volatility. The theory behind the mass spectrometer is to use the difference in mass-to-charge ratio (m/e) of ionized atoms or molecules to separate them from each other. Mass spectrometry is therefore useful for quantitation of atoms or molecules and also for determining chemical and structural information about molecules. Molecules have distinctive fragmentation patterns that provide structural information to identify structural components.
The combination of the gas chromatograph and mass spectrometer is very easy, because both instrument needs to be modified in excess and both are analyzed in the gas phase and have comparable sample levels and temperature ranges. The ! most important feature of the tw o instruments being coupled is that they perform complementary analytical functions.The instrumentation of the gas chromatograph/mass spectrometer is very complex. The instrument's parts include an injector, a carrier gas, a column, a separator, an ionization source, mass separator, and an ion detector.
The injector is located on the gas chromatograph and is where the sample gas is injected into the instrument to start the process. The sample gas is then mixed with a carrier gas, which is the mobile phase in gas chromatography. The mixture proceeds into the capillary column where the separation of the sample begins. The capillary column is 15 to 60 meters in length and .25 to
There are many internal parts to the injector. Starts with a barrel then moves down to a plunger then there is a check valve, below that is a spacer with the nozzle springs inside of it, lastly is the nozzle. All of these parts have specific and unique jobs. Nozzle has a needle in it that works kind of like a piston that once the pressure build up the needle forces forward and sprays fuel. There is a spacer above the nozzle with the nozzle springs that force the needle down. Above the spacer is a check valve, the check valve allows the right amount of fuel into the nozzle. The plunger and barrel are located above the check valve. It has a spring on the plunger that has to hold resistance of the pressure until it reaches the correct amount before it will let the injector fires. There is two internal o-rings one that is around the plunger and one that sets between the nut and body.
5. Two or more samples may be applied to each plate if they are kept
The procedure of the lab on day one was to get a ring stand and clamp, then put the substance in the test tube. Then put the test tube in the clamp and then get a Bunsen burner. After that put the Bunsen burner underneath the test tube to heat it. The procedure of the lab for day two was almost exactly the same, except the substances that were used were different. The
After performing the first Gas Chromatography, we took the organic layer, and mixed it with saturated Sodium Hydroxide. We performed this step to remove the (-OH) group from the Eugenol. The purpose was to make the water as a product, which can also be used as a solvent for the Eugenol that was ionized, for the two substances Acetyl Eugenol and Beta Caryophyllene. Again, we see the density differences in the solvents; we were able to take the organic layer. Finally, we transferred the layer into the beaker and dried, to perform the Gas Chromatography
AMS determines the isotopic composition of a sample material by first producing a negatively-charged ion beam, which is then subjected to a series of extremely selective filtering procedures in order to find C-14.
There are a number of examples of works done before the twentieth century in which experiments were conducted. However, Michael Tswett used column liquid chromatography in which the stationary phase was a solid adsorbent packed in a glass column and the mobile phase was a liquid. He conducted experiments on extracts of chlorophyll in gasoline oil over 100 adsorbents. Most of these adsorbents are now no more important. Interestingly, the list of the inclusion of materials such as silica, alumina, carbon, calcium carbonate, magnesia and sucrose are still in use. He also confirmed the identity of the fractions obtained by the spectrophotometry at different wavelengths thus anticipating the most common mode for in liquid chromatography. In 1910 Tswett obtained his Doctrate degree and his doctoral research paper was published as a monogram which once again demonstrated his ideas for further development and improvement. That monogram marked the end of his chromatographic work. This is not surprising, because he was a botanist and chromatography is only a means and not an end. Chromatographic techniques had been ignored until 1930. One of the few exceptions was the work of an American L.S. Palmer, who in 1930 published his work for the description of the separation af plant and other dairy pigments. There are several reasons for the lack of interest in chromatography , for the moment, the main thing is that it
Atomic Absorption (AA) Spectroscopy is a quantitative analysis technique that uses the absorption of light through a flame and gaseous chemicals. AA Spectroscopy can be used for a multitude of purposes, most notably finding the concentration of one or a few elements in a compound. AA Spectroscopy can work in two different ways using an open flame and gaseous chemicals or a graphite furnace. Flame AA Spectroscopy works by taking a compound or element and disassociating it into an aqueous solution. The solution is then blown through an incredibly small nozzle which nebulizes the liquid into a very fine mist. The nebulized liquid is then blown through a flame with a very small beam of light passing through it. This light beam detects different elements in the flame and uses the known light absorbance of the element to determine the concentration of the element in the solution. The other form of AA Spectroscopy uses a graphite furnace to heat up and incinerate a sample. A solid compound is placed in the furnace which then heats up to 2000-3000 C effectively atomizing the compound and in the process turning the rest into ash. The light beam is then shot through the furnace as the solid is being heated and subsequently atomized and the machine records the absorbance rate much like the Flame AA Spectroscopy would. The difference between flame and furnace spectroscopy is in the atomization of the sample; because the Flame Spectroscopy uses pressure to atomize the compound, much of the compound is lost when sprayed
In an effort to make drug testing for employees of the federal government more accurate, to deter false positives and false negatives it has been suggested to use alternative methods of testing. The Associated Press reported a movement by the federal government to "overhaul its employee drug testing program". (TAP, pg 1) Currently, the government tests its employees during the pre-employment selection and when accidents
The main psychoactive component of marijuana is (9-tetrahydrocannabinol (THC). Other prominent cannabinoids include cannabidiol, cannabinol, and (9-tetrahydrocannabinic acid. Together, these compounds contribute to various behavioral and cognitive changes, which can slightly differ based on the route of preparation and administration (Farthing 1992). THC is found in the sticky resin of the cannabis plant, with the highest concentration in the flowering tops (buds) of the female plant. Marijuana is a preparation of the leaves, stems, and buds, while hash is a concentration of the resin. Smoking and oral ingestion are the most common ways of administration and can produce slightly distinct effects due to the different filtering methods of the digestive tract and lungs.
Therefore, the gas chromatography could not be performed to determine its composition. The ratio of the three samples obtained, were not all accurate. The first sample, of pure hexane should have had a ratio close to 100% hexane to 0% heptane. The second ratio should have been close to 50% hexane to 50% heptane and the third should have been the reverse of the first sample, with 0% hexane to 100% heptane. The boiling point of hexane is around 65°C and the boiling point of Heptane is 100°C. The first sample’s error could have occurred due to the late extraction of the sample. When the boiling point was reached, the extraction of the sample from the distillation vial should have occurred immediately, not doing so caused some of the vapors from heptane to be included into the first sample. This could be prevented next time by lowering the heat of the Variac transformer, which would have allowed for the heating of the compound to be slower than what it was
Forensic toxicologists employ a large number of analytical techniques to determine the drugs or poisons relevant to an investigation; the capacity of a laboratory to conduct routine toxicological analysis varies depending upon equipment, technical capability and analyst experience. When needed, there are specialty toxicology labs that can test for almost any potential toxin or metabolite in almost every kind of post-mortem sample. A laboratory should be accredited to perform the analytical work and must be subject to regular inspections. This will ensure that laboratories can reproduce accurate and reliable results for investigations. All laboratory tests conform to standard operating procedures, results are confirmed to meet standards, and reported results are peer reviewed by a second toxicologist before being released. Even so, we still use methods that Gettler used in his
After the some time, we filter it through a Büchner funnel before it is recrystallized and filtered again. The mass was recorded as it was dry. By adding sodium carbonate, we will now test whether what obtained is benzoic acid or not, because one can observe bobbles if it is an acid. After that we burn it to test if it is aromatic.
Drug abuse in the workplace is a very serious challenge faced by employers. The reason that drug abuse within the workplace is so serious is because it can negatively affect the company itself, the employee that is abusing the drugs, and fellow co-workers within that area. Even though we have not found the answer to completely eliminate drug abuse and bringing drugs into the workplace, drug testing is one of the most effective methods for employers to eliminate the potential harm that employees could bring into the workplace. Many variables are at risk when dealing with drug abuse in the workplace such as the quality and productivity of the goods and services offered by the company, the liability of the company
Drug testing can be a scary process, although it can be a very easy test for those people who don’t take drugs and don’t throw fits about it
From cocaine to marijuana, drugs come with different names and different symptoms. Cocaine for instance has symptoms of increased body temperature, increased heart rate, and increased blood pressure. Methamphetamine (meth) on the other hand includes symptoms of a wired feeling, extreme weight loss, shaking, anxiety, and hallucination. Another drug is marijuana which includes side effects such as compulsive eating, bloodshot eyes, occasional paranoia, and hallucinations. Lastly and one of the most addictive is heroin which includes symptoms of euphoria, entering into a dreamlike state, or heroin could even act as a stimulant. All these drugs are different in their own way but some are connected because of their classification. Classifications of drugs include stimulants, cannabis, hallucinogens, antidepressants, depressants, narcotics, and inhalants.