Standardized Testing Essay examples -- Standardized Testing Essays

Web based Health Care Essay Example | Topics and Well Written Essays - 750 words

Online Health Care - Essay Example Destinations need to pursue the HONcode to guarantee that they follow the eight standards of this code. Through this then people can look at for the red and blue seal of the HONcode on the sites they visit to search for data on various wellbeing conditions. One case of a site is the American Diabetes affiliation that gives nonstop consideration to the diabetes patients and empowers others to find out about the administration, determination and manifestations of diabetes. It likewise prompts people on what to eat and what nourishments to dodge by giving out plans. The primary target of this site is to fix and forestall diabetes and to improve the lives of the considerable number of people influenced by diabetes. The eight standards of the HONcode involve: the authority of the information gave, data protection and privacy; exact attribution of sources; the straightforwardness of financial sponsorship; the centrality of clearly isolating publication content from publicizing; complimentary information that doesn't supplant yet underpins the patient-specialist relationship, and back up attestations concerning execution and advantages. The American Diabetes Association (ADA) site is one of the destinations that are keeping the eight guidelines of the HON code. In definitive, when the website distributes a diary about diabetes and made accessible online for people to get to it and advantage from the data, the creators of the diaries and their capabilities are constantly shown. Moreover, the locales stays with the third code which is protection, since if a guest shares data online to the website, the webpage doesn't let the data known to any client of the website as it guarantees the data is made private and classified. Likewise, if data has been gained from different sources, the site guarantees that it has incorporated the references, the page of the diary from where the data was recovered, and the date the diary was distributed. Through this, the site is attempting to

Why the MLA Essay is So Important

Why the MLA Essay is So ImportantIf you are looking for an easy way to get into a better school for medical career training, then the MLA essay should be one of your first choices. The essay is very popular and is held in high regard because it does a great job of presenting the facts and information that will help a student to build a strong foundation for the future. In this article, I will discuss why the MLA essay is so important, what the format is like, and how it can help you.The purpose of the MLA essay is to present the information and facts that will lead the reader to the goal of pursuing a career in the medical field. This might be a career as a primary care physician, or perhaps as a senior level analyst, doctor of osteopathy, or even as a specialist in a specific specialty. The goal is to help the reader understand the medical profession and how it works.You may be wondering how the MLA essay actually works, and what it consists of. The format of the essay is quite stra ightforward. There are two parts: the introduction and the body. The introduction is very important because it introduces the reader to the topic of the essay. In addition, the introduction should contain information about the institution that approved the essay, as well as the actual medical organization and career path.The body of the MLA essay consists of your summary, which should provide a succinct summary of the material presented in the introduction. The summary should include a bit of information about yourself and why you were selected to write the essay. The summary should not be too long, and it should be noted that there is a limit on the length of your summary.The most basic format for the essay is a paragraph. Each paragraph should be written as a separate essay, and it should be noted that each paragraph is different from the next. It is best to write a paragraph in the first person and the paragraph in the third person. When writing a paragraph, it is good to have a set of rules in mind, such as: first, introduce the topic; second, provide an overview of the material presented; third, provide information on yourself; and fourth, summarize the information you have provided.The style of the MLA essay is quite simple. Many people write their sentences on the first or second person, but others prefer to write in the third person. Whether you choose to write in the first or third person, you should always maintain a regular cadence to keep the content flowing.If you are writing the essay for an exam, it is best to practice in front of a mirror, or a friend, to make sure that you are writing clearly and as concisely as possible. The idea is to write as clear and concisely as possible, so that when you finally sit down to write the essay, you will do so clearly and effortlessly.It is certainly not necessary to use the MLA format in order to have a successful essay. There are a variety of essay formats, and it is certainly possible to write a powerful essay using a variety of formats. However, the format of the MLA essay will help you to be more focused and organized, and will give you a solid foundation for the rest of your career.

The Killer Angels Essay examples - 1035 Words

The Killer Angels Mine eyes have seen the glory . . . The spy was the first to see the Union army march through the valley. He noted that the army was moving fast and marching in extreme heat. His intentions now were to return and report this information to the General Robert E. Lee. Lieutenant General James Longstreet received him back at camp, and the spy let him know of the information, which he had obtained. Longstreet found it useful information to pass on to Lee. Both Lee and Longstreet were skeptical of this information, but if the spy was right they would be in extreme danger. After viewing the map, Lee decided to go ahead and move his army towards Gettysburg, which would be the direction in which the Union army would†¦show more content†¦All he needed to do was hold the hill till morning when reinforcements would arrive. Wednesday, July 1st, 1863 . . . of the coming of the Lord On this morning Lee spoke with Longstreet, about how he would like for him to stay behind in the battle so that he would not lose him. Longstreet agreed but also brought notice to Lee about the Union cavalry was already in Gettysburg. Lee was caught by surprise; being told earlier that only militia was seen there. Lee reported that it was John Buford, and that infantry was soon to come if the cavalry was already there. Longstreet thought of taking the defensive end and waiting for Buford to attack. Lee on the other hand disagreed with the defensive tactic and wanted to attack Buford. Of course Lee was above Longstreet and would get his way. Buford woke in the morning only to smile and smirk as he heard General Heths men trying to put up a fight and take his hill. He was not worried of Heth, but worried of what was to arrive behind Heth. Buford knew that if Lee were to arrive and attack, then he would lose the battle and also the hill on which he stood. Major General Reynolds arrived shortly after the battles that were going on that morning. Buford was very glad to see him and his infantry. Later that day in another short battle, Buford caught a glimpse of Reynolds as he rode into battle, only to later turn and see Reynolds dead on the ground. The battle stillShow MoreRelatedEssay On Killer Angels1776 Words   |  8 PagesKiller Angels is a 1974 historical novel by Michael Shaara. The book tells the story of the Battle of Gettysburg in the American Civil War. The novel is told through the voices of both Union army and Confederate Army of Northern Virginia leaders who were in battle there. The novel is laid out in days and each new chapter for the day gives a number and the name of the man who is the focus of the chapter. In Killer Angels, the Army of Northern Virginia’s demise is highlighted by a few different featuresRead More Killer Angels Essay2541 Words   |  11 Pages The Killer Angels The Battle of Gettysburg brought the dueling North and South together to the small town of Gettysburg and on the threshold of splitting the Union. Gettysburg was as close as the United States got to Armageddon and The Killer Angels gives the full day-to-day account of the battle that shaped America’s future. Michael Shaara tells the story of the Battle of Gettysburg through the eyes of the generals and men involved in the action of the battle. The historical account of the BattleRead MoreKiller Angels Essay714 Words   |  3 PagesKiller Angels The pain, joy, bloodshed, death, and sorrow of the Civil War are all contained in the book called, The Killer Angels. This book will show you the thoughts, feelings and actions of many of the leaders of both armies. By reading this book you will get an in depth view of the bloodiest days of the Civil War. Even if you know absolutely nothing about this war, you can still read and understand everything that is portrayed. This story not only gives you the view of many of theRead MoreThe Killer Angels By Michael Shaara1634 Words   |  7 PagesAuthor Background Pulitzer Prize-winning author Michael Shaara, the author of The Killer Angels, was born on June 23, 1928 in Jersey City, New Jersey. He was an author of science fiction, sports fiction, and historical fiction. Although writing was his passion, Shaara was very athletically successful in high school, winning more awards than any other student in the history of the school for sports such as basketball, track and baseball. He acquired a skill in boxing, and of the 18 matches ShaaraRead MoreThe Killer Angels By Abraham Lincoln1046 Words   |  5 Pagesagainst itself cannot stand.† Lincoln believes that there is no such thing as a balance between free and slave states and that the two contradictory governments are bound to fall. That describes the conflict that occurs in the fictional novel, The Killer Angels, a civil war story between the Union and Confederate states fighting to achieve the government they yearn for. The setting takes place in the midst of the Battle of Gettysburg as the two sides prepare for the fight. The Confederate officers include:Read MoreThe Killer Angels Book Review1641 Words   |  7 PagesKatie Cline The Killer Angels Book Review June 21, 2012 The Killer Angels by Michael Shaara: The Random House Publishing Group, New York, 1974. The Killer Angels is a stunning recollection of the telltale battle of the Civil War: the Battle of Gettysburg. Set from June 29 to July 3, 1863 and told from the vantage points of several soldiers and commanding officers from both sides, including Lee, Longstreet, and Chamberlain, Michael Shaara effectively paints a picture of the war that divided AmericaRead MoreThe Killer Angels By Michael Shaara1206 Words   |  5 PagesShawn Gacy American Lit. Mrs. Moyer September 11, 2015 Summer Reading The book I chose to read over the summer was the book The Killer Angels, by Michael Shaara. The Killer Angels tells the story of the Battle of Gettysburg. On July 1, 1863, the Confederate army, and the Union army, fought the largest battle of the American Civil War. When the battle ended, fifty one thousand men were KIA (Killed In Action), wounded, or MIA (Missing in Action). All the characters in this book are basedRead MoreThe Killer Angels By Michael Shaara1061 Words   |  5 PagesThe Killer Angels is a novel written by Michael Shaara which tells the story of the four day battle of Gettysburg from June 30 and ended July 3, 1863.There were two armies in the novel the Union and the Confederate soliders who eneded up fighting in a town called Gettysburg located in Pennsylvania. In the novel, there are four major characters who were all Generals, General Lee, General Longstreet, General Pickett, and Colonel Chamberlain.The main cause of the war was the confederate wanting to splitRead MoreThe Killer Angels By Michael Shaara1117 Words   |  5 Pages Michael Shaara’s 1974 historical novel, The Killer Angels, covers the story of the four days of the Battle of Gettysburg that also features maps for visualization. The format of the story is well organized. It begins with a Foreword, which describes in great detail the armies and soldiers involved in the battle. It follows up with four sections and within each section there are chapters that are written in chronological order, covering the events between Monday, June 29, 1863 and Friday, July 3Read MoreThe Killer Angels By Michael Shaara1947 Words   |  8 Pagesthe dueling North and South together to the small town of Gettysburg and on the threshold of splitting the Union. Gettysburg was as close as the United States got to Armageddon and The Killer Angels gives this full day-to-day account of the battle that shaped America’s future. Michael Shaara author of â€Å"The Killer Angels,† tells the story of the Battle of Gettysburg through the eyes of generals Robe rt E. Lee, Joshua Chamberlain, James Longstreet, and John Buford, and the other men involved in the action

The Economic Impact Of Illegal Immigration - 1603 Words

Abstract This paper examines the economic impact of illegal immigration in the United States. This country was built with the help of millions of legally admitted immigrants, however today illegal immigration is a controversial topic. Despite the illegal status, millions of men and women work and contribute to local, state and national economies. An accepted idea is that most of the illegal immigrants cross the Mexico-US border, therefore most of the illegal immigrants should be Mexicans or from South America. Is this true? Are there official numbers confirming this impression? Another relevant question is if the illegal immigrants leave their countries with the only intention of work and make a decent living, or they have other intentions coming to America? If millions of people want to work then it is undeniable that such a large work force would have an impact in the country’s social structure and especially in the economy. Economic Impact of Illegal Immigration in the United States As an adult immigrant I had the opportunity to experience what it is to leave my country and come to America with dreams, hopes and ambitions. I had the opportunity to stay and become a citizen, with the intention of being a productive member of this society. However many immigrants entered the country illegally or they remain in the country longer than allowed. They are known as illegal immigrant, illegal aliens, illegals or undocumented immigrants. Even though some people claim technicalShow MoreRelatedThe Economic Impact Of Illegal Immigration1520 Words   |  7 Pagessection-04 November 19, 2014 Illegal immigration Economic impact of illegal immigration The idea of illegal immigrants has been tarnished by the media. The first thought that pops in to our minds when the topic of illegal immigrants has been brought up is the fact that these people take all the jobs and depress the economy of a country. They have always carried with them a negative connotation, especially in countries like America. This conservative view of illegal immigration has hijacked the minds ofRead MoreThe Economic Impact Of Illegal Immigration902 Words   |  4 PagesThe economic impact of illegal immigrants in Texas has brought concerns for the state s economy. Such as opportunities, health care, and education. Illegal immigrants contribute both positively and negatively to the Texas economy. They contribute positively by paying for taxes such as sales taxes, health taxes and taxes imposed on items. The negative impacts these immigrants have on the Texas economy seems to overweigh these positive impacts. Their presence has made general wages go down for unqua lifiedRead MoreIllegal Immigrants Are Good For The Economy Of The United States1250 Words   |  5 PagesStates, the country has attracted immigrants from different parts of the world. Illegal immigrants form the larger proportion of the immigrants into the United States. Policy analysts, government officials, as well as scholars have sought to ascertain the political, social, and economic impacts of the illegal immigrants (Hanson 11). Particularly, there has been raging debate regarding the economic impact of illegal immigration to the United States of America. It has become a matter of debate and studyRead MoreImmigration On The United States1302 Words   |  6 PagesImmigration Rights in the U.S. Immigration has occurred in the U.S. for for many years. Some say it’s the foundation of our country. America is the country where people leave their own country to live. People would leave due to mistreatment, hunger issues or job opportunities. America is known for starting over or accomplishing dreams, so immigrants travel over to follow those dreams. People emigrate from one country to another for a variety of complex reasons. Some are forced to move, due to conflictRead MoreWhat I Learned From The Group Project On The United States Illegally By Their Parents Should Be Deported Essay1575 Words   |  7 Pagescitizenship which is in opposition to my thoughts. My view for path to citizenship is based more on impacts to the children and ensuring they are not negative. What surprised me first and foremost was that the research didn’t provide me a clear answer that supported or refuted my view. There is no clear answer, both sides have valid opinions, and there wil l be both negative and positive impacts. No matter what course of action is taken, the most important consequence is that the children are notRead MoreOpen Border Policy and Illegal Immigration1844 Words   |  7 Pagesï » ¿Open Border Policy and Illegal Immigration Introduction Immigration is one of the contentious issues that continue to elicit mixed reactions from different parties. In most western economies, debates on immigration policies have been on the rise in the recent decades. Whereas the international human rights have confirmed that freedom of movement is one of the basic human rights and hence no one can be deprived, most governments have put restrictions on immigration. Furthermore, the enactmentRead MoreEvaluating Arguments, Opinions, And Beliefs Project Essay1633 Words   |  7 Pagescitizenship which is in opposition to my thoughts. My view for path to citizenship is based more on impacts to the children and ensuring they are not negative. What surprised me first and foremost was that the research didn’t provide me a clear answer that supported or refuted my view. There is no clear answer, both sides have valid opinions, and there will be both negative and positive impacts. No matter what course of action is taken, the most important consequence I learned is that the childrenRead MoreIllegal Immigration And The United States1481 Words   |  6 PagesPurpose Statement Illegal immigration can cause substantial tension on the current economic configuration in a country. However, it can also, assist the said configurations by providing cheap and effective manpower at the same time. Contemporary study on political opinions concerning immigration frequently pits points of view highlighting economic self-interest versus cultural or ideological rationalization. They (studies) are also based on the particular immigration policy at hand at the time,Read MoreThe Devastating Impacts Of Illegal Immigration1368 Words   |  6 PagesDevastating Impacts of Illegal Immigration† If ever there was a polarizing problem growing in the U.S., illegal immigration is definitely exploding to the top. This issue is at the center of the political arena and debate. It has the heart and minds of the nation stirring. President Obama wrote, We have to deal with the 11 million individuals who are here illegally. We all agree that these men and women should have to earn their way to citizenship. But for comprehensive immigration reform toRead MoreDo Illegal workers help or hurt the economy1582 Words   |  7 Pagesï » ¿Do Illegal Workers Help or Hurt the Economy? While growing up in Mexico, I heard many stories of people who were going to work in the United States, some illegally, so they could provide a better life for their families. To them, they were going to the land of opportunity, where jobs were plentiful for people who were willing to work hard. They planned to go to the United States and do the work that Americans didn’t want, while getting paid more than they could make in Mexico. Many

Do Primates Posses Culture Essay Research Paper free essay sample

Make Primates Posses Culture? Essay, Research Paper Writing Assignment One # 8211 ; Do primates posses civilization? I think that if civilization is defined as erudite behaviour, than it is sensible to state that primates posses a signifier of civilization. Primates have been observed doing tools to help in roll uping nutrient and developing communicating system, both of which are learned behaviours. It is common in monkeys, apes and worlds that behaviour and societal organisation aren? t needfully programmed into the cistrons. There have been several instances where an full troop has learned from the experiences of merely a few. In a group of Nipponese macaques, for illustration, a three-year-old female female developed the wont of rinsing soil of of Sweet murphies before she ate them. First her female parent, and so equals and so the full troop started rinsing their murphies excessively. Another macaque troop has a similar experience when a group of dominant males learned to eat wheat. We will write a custom essay sample on Do Primates Posses Culture Essay Research Paper or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Within an hr, the pattern had spread throughout the full group. Changes in erudite behaviour seem to distribute more rapidly from the top down than from the underside up. For monkeys as for people, the ability to larn is a enormous adaptative advantage, allowing them to avoid fatal errors. Faced with an environmental alteration, primates Dons? Ts have to wait for a familial or physiological response, since learned behaviour and societal forms can be modified. The extended use of tools among Primatess can besides be sited as civilization. Chimpanzees have been observed crumbling up foliages to dunk in H2O than they can non acquire to with their oral cavity and utilizing the foliages as sponges. This sort of pattern goes beyond carnal inherent aptitude. Another extremely developed pattern is? ending? . Chimps carefully choose the right sort of branchlet to examine the white ant hills with. They modify the branchlet by desquamation of f the bark to expose the gluey surface. Then they dig holes with their fingers, stick the branchlet in and angle around until the have adequate white ants on their branchlet to hold a repast. Ending takes clip, and their are many Gombe Pan troglodytess that have neer mastered it. Merely certain types of branchlets will work for the occupation. Besides, one time the branchlet is in the hill and the Pan troglodytes Judgess that the white ants are creeping on its surface, the Pan troglodytes has to rapidly toss the branchlet as he pulls it out so that the white ants are on top, otherwise they would all fall off. The cultural transmittal of a communicating system through acquisition is a cardinal property of linguistic communication. Trained Pan troglodytes? s Washoe and Lucy have tried to learn Ameslan to other animate beings, including their ain progeny. Washoe has taught gestures to other Pan troglodytess at the institute where she is, including her boy, Sequoia, who died when he was really immature. There has been other instances of cultural transmittal from Pan troglodytes to chimp. Chimps and gorillas have at least a simple capacity for langueage. They may neer hold invented a meaningful gesture system in the natural state. However, given a system, they show many human like abilities in acquisition and utilizing it. Of class, linguistic communication usage by apes is a merchandise of human intercession and instruction. The experiments wear? t suggest that apes can contrive linguistic communication. But immature apes have managed to larn the rudimentss of gestures and linguistic communication. Apes, like worlds, may besides seek to learn their linguistic communication to others. Lucy, non to the full recognizing the difference between archpriest custodies and felid paws, one time tried to model her pet cat? s paw into Ameslem marks. There is more than adequate cogent evidence that primates have the capacity to larn behaviour, and efforts to learn it to others. If civilization is defended as erudite behaviour, it seems sensible to propose that primates to hold civilization.

Isolation and Analysis of Essential Oils Using Gas Chromatography Essay Example

Isolation and Analysis of Essential Oils Using Gas Chromatography Paper Isolation and Analysis of Essential Oils using Gas Chromatography Lyndon Justin T. Guzman Institute of Chemistry, University of the Philippines, Diliman, Quezon City Date Performed: February 2; February 4, 2011 Date Submitted: February 18, 2011 Abstract The purpose of this experiment is to isolate the essential oil from eucalyptus leaves as a pure compound; moreover, the components of the essential oil, camphor and limonene, will be then separated using gas chromatography technique, identify the components by their retention times, and compute for the concentration and percentage content of each component by their peak areas and peak heights. The volatile oil from eucalyptus leaves was isolated with the use of steam distillation setup, then using a separatory funnel to pipette out the extract from the distillate. A gas chromatography, with nitrogen gas as the carrier gas and a flame ionization detector, was used to separate and characterize the components of the essential oil. The retention times, peak areas, and peak heights were obtained for qualitative and quantitative analysis. A percentage of 0. 05% and 2. 85% were obtained as the content of camphor and limonene in the extracted oil, respectively. It also goes to show that limonene has greater concentration than that of camphor in the essential oil extract. Indeed, steam distillation and gas chromatography techniques are essential methods for extracting essential oils and separating natural compounds from plants. I. Introduction Gas chromatography is used for separations of volatile or reasonably volatile organic liquids and solids. In this method of chromatography, the components are partitioned between a liquid coating on the column (the stationary phase) and an inert gas (the mobile phase). We will write a custom essay sample on Isolation and Analysis of Essential Oils Using Gas Chromatography specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Isolation and Analysis of Essential Oils Using Gas Chromatography specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Isolation and Analysis of Essential Oils Using Gas Chromatography specifically for you FOR ONLY $16.38 $13.9/page Hire Writer The stationary phase for gas chromatography is usually an organic polymer coated on the inside of a tube, such as long capillary, and the mobile phase is an inert gas, such as hydrogen, helium, or nitrogen. (Druelinger, 2000) Figure 1. Schematic diagram of a gas chromatographic system. http://www. cee. vt. edu/ewr/environmental/teach/smprimer/gc/gc. html A small volume (1-10 ? L) of a mixture of volatile substances (usually dissolved in a solvent) is injected by syringe onto a heated column through which an inert carrier gas is flowing. The heat applied, as well as the gas flow, helps the molecules from the sample travel through the column. Smaller, more volatile molecules generally emerge first from the opposite end of the column and are detected. The detector is connected to a recorder/data system, which shows a deflection when a sample passes the detector in proportion to the amount of sample detected. Compounds are eluted through an exit port either in an intact form or as combustion products, depending on the type of detector used. (Druelinger, 2000) The characteristic aromas of plants are due to the volatile oils, or also known as essential oils, which have been used since antiquity as a source of fragrances and flavorings. These oils occur in all living parts of the plant; they are often concentrated in twigs, leaves, flowers, and seeds. Essential oils are generally complex mixtures of hydrocarbons, alcohols, and carbonyl compounds mostly belonging to the broad group of plant products known as terpenes. (Dalrymple and Moore, 1976) One of the many types of samples easily characterized by the technique of gas chromatography is the essential oil. These essential oils are isolated from the plant tissue by steam distillation. Since organic compounds are generally miscible with one another, this phenomenon is usually observed only when one of the liquids is water with one or more immiscible organic liquids; in these cases, the distillation process is called steam distillation (Ault, 1983). The technique of steam distillation is based upon the principle that each component of immiscible liquid mixtures contributes to the total vapor pressure as if the other components were not there (Druelinger et. l. , 2000). As the temperature of such a mixture in an apparatus open to the atmosphere is raised, the vapor pressure of each substance increases until the total vapor pressure equals the pressure of the atmosphere. Since the total vapor pressure is the sum of the individual vapor pressures, the total vapor pressure must become equal to atmospheric pressure at a temperature below the boiling point of either pure substance (Ault, 1983). The mixture thus distills at a temperature below the boiling point of either pure component. This can be explained using a combination of Dalton’s and Raoult’s Law: Patm = XAPÂ °A + XBPÂ °B where Patm is the atmospheric pressure, XA and XB are the mole fractions of compounds A and B, and PÂ °A and PÂ °B are the vapor pressures of pure liquids A and B. Their individual contributions are dependent on their respective mole fractions, and both liquids contribute to the vapor pressure of the system (Institute of Chemistry, UPD, 2010). In this experiment, a major constituent of volatile oils from eucalyptus leaves will be isolated as a pure compound with high purity via steam distillation. These essential oils are camphor and limonene and by using the gas chromatography technique, the different components of the eucalyptus essential oil will be separated. This experiment also aims to manipulate the gas chromatography system and change conditions in order to effectively and efficiently separate the components, and therefore achieve a good resolution. The components will be identified by determination of their retention times relative to those of a homologous series of n-alkanes by co-injection with authentic (standard) samples. II. Methodology Extraction of Essential Oils by Steam Distillation A steam distillation setup was prepared as shown in Figure 2 below (Note 1). The sample (Note 2) was cut into small pieces and an amount enough to fill three-fourths of a 1-L round bottom flask was collected. 400-mL distilled water was weighed and added into the flask. The mixture was steam distilled rapidly until you have about 100 mL of the distillate. Figure 2. Steam distillation setup. http://www. pharmainfo. net/reviews/fractional-distillation-binary-solvent-mixture The distillate was placed in a separatory funnel and 2. 0 g NaCl was added. The funnel was left to stand until separation of layers occurred. All the extract was then pipetted out (Note 3). The mixture was dried by adding enough anhydrous sodium sulfate to the mixture until the sodium sulfate swirled freely. If the entire drying agent clumped, another spatula-full anhydrous sodium sulfate was added. The mixture was then swirled. The mixture was dry if there were no visible signs of water and the drying agent flowed freely in the container. The essential oil and aqueous distillate were stored in separate tightly-sealed, properly-labeled containers (vials) in the freezer for future use in the FT-IR analysis experiment or GC experiment or special project (Note 4). Gas Chromatographic Analysis of Essential Oils Solution Preparation 1. Reference Solution. Separate stock solutions of 500 ppm of camphor and limonene in acetone were prepared. 50-300 ppm working standard solutions were also prepared (50, 100, 150, 200, 250 ppm) (Note 5). 2. Essential Oil Extract. 0. 5 mL of the pure extract (from steam distillation) was measured and diluted with acetone in a 10-mL volumetric flask. Instrumentation Gas chromatography was performed using a Shimadzu GC-14B using Equity 1 (30 m x 0. 25 ? m ID, 0. 25 mm film thickness) capillary column with N2 as a carrier gas. The following were the operating conditions: N2 flow rate| 1. 0 mL/min| Column temperature| initial 50Â °C (at 4 mins)| Ramp| 20Â °C/min to 210Â °C| Injector temperature| 200Â °C| Detector temperature| 250Â °C| Before the start of the experiment, the GC must have warmed up. Refer to the GC condensed procedure. Gas Chromatographic Analysis 1. 0 ? L of the standard camphor solution was injected and its chromatogram was generated. The procedure was repeated using limonene standard solution. The recorded retention times and peak areas of these substances were noted. 1. 0 ? L of the test solution (essential oil extract) was injected. Using the retention times determined from the chromatogram with the standard solution, the components of the standard solution was located on the chromatogram obtained with the test solution (Note 6). After all solutions have been injected and data computer-processed, the GC was left to run at the highest column temperature used in the experiment with the N2 gas flowing at a slower rate than the experimental flow rate for 15-20 minutes. The injector temperature was set to room temperature and slowly lowered the column temperature down to room temperature with the N2 gas still flowing in the system. Once everything reached room temperature, the gas flow was left to stand for another 10-15 minutes, after which the GC can be turned off. Notes 1. Boiling chips were added to the steam generator and sample flasks. 2. Each group must use different plant samples. 3. There should be two layers after the addition of NaCl solution. One was mostly water. The other was mostly extracted oil. To find out which is which, a small amount of water was added to the flask, whichever layer dissolved the water drop was the aqueous layer. The layer of essential oil was then carefully pipetted out. . If you have to get more of the organic layer out of the water, you can perform a back-extraction (solvent extraction) experiment. 5. All standard and sample solutions were stored in a well-filled, airtight container, protected from light and a temperature not exceeding 25Â °C. 6. The assay was not valid unless the number of theoretical plates calculated for the peak due to limonene at 110Â °C was at leas t 30000; the resolution between the peaks corresponding to limonene and cineole was at least 1. 5. Waste Disposal All solid wastes were disposed in the trash can. Waste acetone was poured into properly labeled waste container exclusively for acetone. Do not pour waste acetone in the sink! III. Results and Discussion The extraction of the essential oils, camphor and limonene, from the eucalyptus leaves sample was carried out using the steam distillation technique. camphor Figure 3. Structural formulas for camphor and limonene. The boiling point of the oily, aqueous distillate will never exceed the boiling point of water. This is because both water and the oily component each contribute to the total vapor pressure as if the other component was not present. The mixture boils when the combined vapor pressures of water and oil equal the atmospheric pressure. The oil has a small, but significant vapor pressure at 100Â °C, so that the boiling point of the mixture will be just below the boiling point of water. (Druelinger, 2000) The mass of the eucalyptus leaves that were extracted was 112. 98 g. 100 mL of the distillate was produced from the steam distillation. Only a small amount of oil was extracted within the distillate by a separatory funnel. The components of the oil sample were then separated and characterized using the gas chromatography technique with a flame ionization detector. Nitrogen gas served as the carrier gas or the mobile phase that moved the sample throughout the column. The chromatograms, plots of detector response versus time, of the standards and the sample were taken. Retention times were noted for qualitative analysis. Peak areas and peak heights were also recorded for and quantitative analysis of the essential oils. Table 1. Retention times of camphor and limonene standard and sample solutions. Solution| Retention Time (min)| pure standard camphor| 9. 021| pure standard limonene| 7. 908| extracted camphor sample| 9. 347| extracted limonene sample| 7. 89| From the given data above for the retention time, the retention time of the camphor and limonene from the standard solutions, 9. 021 min and 7. 908 min, respectively, were close to the retention time of the camphor and limonene with that of the sample solution, 9. 347 min and 7. 889 min. It was deduced that the camphor and limonene from the sample solution were present compounds in the extrac ted oil from eucalyptus leaves. Below is a table shown for the resulted peak areas and peak heights from the chromatograms of camphor and limonene standard solutions. Table 2. Peak areas and peak heights of camphor and limonene standard solutions. Solution| Peak Area| Peak Height| pure standard camphor| 46848| 17109| 50 ppm| 4427| 1113| 150 ppm| 12904| 4627| 200 ppm| 20417| 6065| 250 ppm| 15683| 5282| pure standard limonene| 56156| 20681| 50 ppm| 4419| 1236| 150 ppm| 15058| 4946| 200 ppm| 20464| 6452| 250 ppm| 20875| 5913| Figure 4. Camphor standard solutions vs. Peak area. Figure 5. Camphor standard solutions vs. Peak height. Table 3. Determination of the concentration of camphor component in the sample. Camphor Sample| Value| Concentration (ppm)| Peak Area| 5820| 67. 8| Peak Height| 1544| 61. 57| From the plotted calibration curve on the peak height and peak area for the camphor component, a regression equation is formulated in each curve with linearities almost equal to 1. From the acquired data on peak area and peak height of the camphor sample, the concentration of the camphor is 67. 98 ppm when the peak area is 5820 and 61. 57 ppm when the peak heigh t is 1544. Figure 6. Limonene standard solutions vs. Peak area. Figure 7. Limonene standard solutions vs. Peak height. Table 4. Determination of the concentration of limonene component in the sample. Limonene Sample| Value| Concentration (ppm)| Peak Area| 306384| 2875. 39| Peak Height| 102881| 2943. 95| From the plotted calibration curve on the peak height and peak area for the limonene component, a regression equation is formulated in each curve with linearities also almost equal to 1. From the obtained data on peak and peak height of the limonene sample, the concentration of the limonene is 2875. 39 ppm when the peak area is 306384 and 2943. 95 ppm when the peak height is 102881. To determine the percentage content of the components of the essential oil, the area normalization method is applied. Determining the areas beneath all of the peaks of a chromatogram enables to assign percentages to each of the components of a sample. Table 5. Determination of the percentage content of camphor and limonene sample. Component| Area| Total Area| % Content| camphor| 5820| 10766407| 0. 05%| limonene| 306384| | 2. 85%| Using the formula for area normalization, the computed percentage contents for camphor and limonene are 0. 05% and 2. 85%, respectively. This suggests that there is a greater amount of limonene in the oil extracted from the eucalyptus leaves than that of camphor. The very low percentage implies that extracting and separating natural organic compounds from essential oils give you a very low yield that’s why you need to have huge amounts of starting material to extract from to get a relatively high percentage of its components. IV. Conclusion In this experiment, the essential oil from eucalyptus leaves was isolated as a pure compound by steam distillation. The components of the eucalyptus essential oil, camphor and limonene, were separated using the gas chromatography technique having a flame ionization detector. The components were also identified through determination of their retention times and were confirmed that camphor and limonene are present, having a retention time of 9. 347 and 7. 889, respectively. Calibration curves on peak areas and peak heights on camphor and limonene were formed. Concentrations of the components were calculated and gave 67. 98 ppm and 61. 57 ppm for camphor, and 2875. 39 ppm and 2943. 95 ppm for limonene. The percentage contents of the components were also determined. The essential oil extracted constituted 0. 5% camphor and 2. 85% limonene. Steam distillation is a useful method for isolating high-boiling liquids, such as oils, from other non-volatile organic compounds, such as waxes, complex fats, proteins, and sugars (Druelinger, 2000). Natural oils can be isolated readily by steam distillation. Individual compounds can be separated from the essential oil by gas chromatography wherein the components of a vaporized sample are separated as a consequence of bei ng partitioned between a mobile gaseous phase and a liquid stationary phase held in a column. Gas chromatography is the most widely used technique for qualitative and quantitative analysis for analysis times are short, very small amounts of sample are required and an ideal tool for the microscale and miniscale organic laboratories. If you want to obtain large percentage of compounds from the extracted essential oil, you need to have huge amounts of eucalyptus leaves and it will take you a long time to steam distill. The standards should be injected under the same set of conditions for if not, this will lead to erroneous comparisons of data. You can manipulate some parameters like type of column, carrier gas flow rate, injector temperature, and column temperature to compare some effects on the quantitative breakdown of the experiment. V. References Skoog, D. A. , West, D. M. , Holler, F. J. and S. R. Crouch. 2004. Fundamentals of Analytical Chemistry, 8th edition. Thomson Learning Asia, Singapore. Institiute of Chemistry. Intermediate Chemistry Laboratory II Manual. 2010. University of the Philippines, Diliman, Philippines. Druelinger, M. L. , B. A. Gaddis and A. M. Schoffstall. 2000. Microscale and Miniscale Organic Chemistry Laboratory Experiments. The McGraw-Hill Companies, Inc. , USA. Dalrymple, D. L. and J. A. Moore. 1976. Experimental Methods in Organic Chemistry, 2nd edition. W. B. Saunders Company, USA. Ault, A. 1983. Techniques and Experiments for Organic Chemistry, 4th edition. Allyn and Bacon, Inc. , USA. VI. Appendix Calculations Concentration of camphor component in the sample peak area = 5820 regression equation: y = 103. 48x – 1214. 9 5820 = 103. 48x – 1214. 9 x = 67. 98 ppm peak height = 1544 regression equation: y = 33. 317x – 507. 9 1544 = 33. 317x – 507. 29 x = 61. 57 ppm Concentration of limonene component in the sample peak area = 306384 regression equation: y = 106. 88x – 937. 57 306384 = 106. 88x – 937. 57 x = 2875. 39 ppm peak height = 102881 y = 35. 106x – 469. 43 102881 = 35. 106x – 469. 43 x = 2943. 95 ppm Percentage content of camphor sample %content = (area / total area) x 100 %co ntent = (5820/10766407) x 100 %content = 0. 05% Percentage content of limonene sample %content = (area / total area) x 100 %content = (306384/10766407) x 100 %content = 2. 85% Answers to Questions 1. The gas chromatography technique is used for separations of volatile or reasonably volatile organic liquids and solids. 2. Thermal conductivity detectors (TCD), flame ionization detectors (FID), and electron capture detectors (ECD) are commonly used type of detectors. The thermal conductivity detector, which was one of the earliest detectors for gas chromatography, senses a difference in thermal conductivity of gases eluting from a GC column. The thermal conductivities of helium and hydrogen are roughly 6 to 10 times greater than those of most organic compounds. Thus, even small amounts of organic species cause relatively large decreases in the thermal conductivity of the column effluent, which results in a marked rise in the temperature of the detector. (Skoog et. al. , 2004) Flame ionization detectors, the most widely used and applicable detector for GC, consist of a flame fueled by hydrogen gas. Functional groups, such as carbonyl, alcohol, halogen, and amine, yield fewer ions or none at all in a flame. The detector is insensitive towards non-combustible gases such as H2O, CO2, SO2, and NO2. These properties make the FID a most useful detector for the analysis of most organic samples, including those that are contaminated with water and the oxides of nitrogen and sulfur. (Skoog et. al. , 2004) The electron capture detector has become one of the most widely used detectors for environmental samples because this detector selectively responds to halogen-containing organic compounds, such as pesticides and polychlorinated biphenyls. (Skoog et. al. , 2004) 3. An elution with a single solvent or a solvent mixture of constant composition is isocratic. For samples with a broad boiling range, it is often desirable to employ temperature programming, whereby the column temperature is either increased continuously or in steps as the separation proceeds. 4. polydimethyl siloxane – general-purpose nonpolar phase, hydrocarbons, polynuclear aromatics, steroids, PCBs polyethylene glycol – free acids, alcohols, ethers, essential oils, glycols 5% phenyl-polydimethyl siloxane – fatty acid methyl esters, alkaloids, drugs, halogenated compounds 50% cyanopropyl-polydimethyl siloxane – polyunsaturated fatty acids, rosin acids, free acids, alcohols . Table 6. Internal Standard method for GC. % analyte| Peak height analyte| Peak height internal std| Peak height ratio (analyte/internal std)| 0. 05| 18. 8| 50. 0| 0. 38| 0. 10| 48. 1| 64. 1| 0. 75| 0. 15| 63. 4| 55. 1| 1. 15| 0. 20| 63. 2| 42. 7| 1. 48| 0. 25| 93. 6| 53. 8| 1. 74| unknown| 58. 9| 49. 4| 1. 19| Figure 8. Peak Height Ratio vs. Percent Analyte. regression equat ion: y = 6. 9x + 0. 065 slope = 6. 9 y-intercept = 0. 065 concentration of unknown: . 19 = 6. 9x + 0. 065 x = 0. 16304 standard deviation = 0. 007939 Chromatograms Figure 9. 50 ppm standard solution chromatogram. Figure 10. 150 ppm standard solution chromatogram. Figure 11. 200 ppm standard solution chromatogram. Figure 12. 250 ppm standard solution chromatogram. Figure 13. Pure standard camphor solution chromatogram. Figure 14. Pure standard limonene solution chromatogram. Figure 15. Essential oil extract chromatogram.