Wednesday, April 27, 2011
Thursday, April 21, 2011
PROUD TO BE AN INDIAN
Although modern images & descriptions of India often show poverty, India was one of the richest countries before British rule in India, i.e. during the early 17th Century. Christopher Columbus was attracted by India’s wealth and was looking for a route to India when he discovered America by mistake. India has fed the greed of almost every powerful nation or ruler (that/who looked upon it, during those times) and is poised to be at the top of the world in all aspects.
Below are some drops from the Ocean of India's Heritage.
Sanskrit is considered as the mother of all higher languages. It is the most precise and therefore suitable language for computer software. (A report in Forbes magazine, July 1987).ost ancient and living civilizations (at least 10, 000 years old).
Despite the global meltdown that impacted most emerging market economies, India’s GDP growth of 7.1 per cent for the current year would make the country the second-fastest growing economy of the world.
India has the largest number of biomass gasifier systems in the world producing 656 mega watts (MW) of power.
India was the first country to be accorded the status of a Pioneer Investor in 1987 and was allocated an exclusive area in the central Indian Ocean by the UN for exploration and utilisation of resources.
Export of cars grew by 57 per cent in 2008-09 at 3.3 lakh units. Two-wheeler exports crossed the million-mark on a growth of 22.5 per cent in 2008-09.
India has the maximum number of post offices in the world!
India signed a ground breaking civil nuclear deal with US in 2008 thus facilitating fuel supply for its nuclear reactors. The deal offers potential for a paradigm shift in India’s global role. The importance of the deal does not lie merely in the transfer of nuclear energy. Its importance is psychological. It opens the door to a new era of trust and cooperation between India and the US.
India has the largest number of news channel in the world. It is the fastest growing telecom market in the world and has the lowest call rates on earth.
India is the 3rd largest producer of solar photovoltaic cells in the world producing 2.12 MW of power. India is the world’s 4th largest wind power user.
India is the 9th largest solar thermal power generating country in terms of million units per sq. m. It will have 20 million solar lights installed by 2022 which will save 1 billion litres of kerosene every year.
India has jumped five places to become the world’s 11th biggest exporter of commercial services in 2005, and inched one step ahead to the 29th rank among the largest merchandise exporters, according to the latest statistics by World Trade Organisation.
The Indian Software Industry has grown from a mere US $ 150 million in 1991-92 to a staggering US $ 5.7 billion in 1999-2000. No other Indian industry has performed so well against the global competition.
India is the world’s largest, oldest, continuous civilization.
India never invaded any country in her last 10,000 years of history.
IEEE has proved what has been a century old suspicion in the world scientific community that the pioneer of wireless communication was Prof. Jagdish Bose and not Marconi.
India has the second largest pool of Scientists and Engineers in the World.
India is the second largest English speaking nation in the world.
India is the only country other than the USA and Japan, to have built a super computer indigenously.
GM of Hewlett Packard, Chief Executives of CitiBank, Mckinsey & Stanchart, founder and creator of Hotmail, creator of Pentium chip are all Indians.
On 28 April 2008, a world record was set when India’s Polar rocket successfully placed ten satellites, including the country’s remote sensing satellite, into orbit in a single mission.
India is the world’s second largest producer of small cars. It is the largest newspaper market in the world.
World’s largest electronic ID program is underway in India.
Bollywood with about 400 films every year is the largest centre of film production in the world.
India is the largest producer of milk, cashew nuts, coconuts, tea, ginger, turmeric and black pepper, in the world. It also has the world’s largest cattle population (281 million). It is the second largest producer of wheat, rice, sugar, groundnut and inland fish.
The National Rural Employment Guarantee Act or NREGA, an Indian job guarantee scheme, enacted by legislation on August 25, 2005 is the largest ever – public employment programme visualized in human history.
The Mid-day Meal Scheme is the popular name for school meal programme in India, is the largest school lunch programme in the world, covering 12 million children.
Board of Control for Cricket in India, or BCCI, is the apex governing body for cricket in India is the richest body in world cricket.
The largest employer in the world is the Indian railway system, employing over a million people!
Until 1896, India was the only source for diamonds to the world. (Source: Gemological Institute of America )
The World’s first university was established in Takshila in 700 BC. More than 10,500 students from all over the world studied more than 60 subjects.
* 38% of Doctors in America are Indians.
* 12% of Scientists in America are Indians.
* 36% of NASA employees are Indians.
* 34% of Microsoft employees are Indians.
* 28% of IBM employees are Indians.
* 17% of Intel employees are Indians.
* 13% of Xerox employees are Indians.
Varanasi, also known as Benares, was called “the ancient city” when Lord Buddha visited it in 500 B.C.E, and is the oldest, continuously inhabited city in the world today.
Jaipur(India) hosts the world’s widest concrete building. It has a reinforced concrete cement (RCC) flat roof with a single span of 119 feet.
By volume of pills produced, the Indian pharmaceutical industry is the world’s second largest after China.
ISRO has tested the third biggest solid rocket motor in the world after booster rocket of NASA’s space shuttle and Arianespace’s Ariane-5 launch vehicle.
A mass singalong of 160,000 people in the Indian city of Hyderabad, in Andhra Pradesh, has broken a 72-year-old record for the world’s largest choir.
India is the most attractive stock market in terms of asset allocation.
Indian banks are among top 500 financial brands.
India born steel czar Lakshmi Mittal and Reliance Industries chairman Mukesh Ambani figure in the forbes list of “World’s most powerful billionares” who wield staggering authority and influence far beyond their riches.
The Indian media and entertainment business that grew 15 percent anually since 2006 into a $11.68 billion industry in 2008 is seen to toop $21 billion over the next five years.
United Nations Industrial Development Organisation found that India ranks among the top 12 producers of manufacturing value-added(MVA) .
Indian American Prof. Praveen Jain of Queens University is heading the project to make CFL’s more efficient.
The TATA group, State Bank of India and Infosys Technologies are among 17 Indian firms that figure among the top 50 in the list of the world’s 200 most-reputed companies.
India’s contribution to scientific research and innovation has been constantly rising since 2000 according to a study. The number of articles published in global science journals by Indians has increased from around 17000 in 2001 to more than 27000 in 2007.
India is to be the first international customer of the Boeing P-81 Poseidon variant of the P-8A Poseidon.
Exports from SEZ’s in India have increased by over 25% in the 3 months ended June 2009:a very positive indicator.
India has been ranked the second most-optimistic nation in the world in consumer confidence, according to a survey by global consultancy firm, Nielson.
Indian origin 96-year old, Randall Butisingh, now a Florida resident is the world’s oldest blogger. He runs a popular blog http://randallbutisingh.wordpress.com
Pepsico, the $43-billion beverages and snacks company, had its annual global meet in India for the first time, in 2009.This was the second time this meeting was held outside US. Last time it was in Mexico.
To ensure timely payment of wages to workers under the National Rural Employment Guarantee Act (NREGA), more than two crores worth of saving bank accounts have been opened in banks and post offices across the country. This is the largest number of bank accounts linked to a development programme across the globe.
Volunteers in Dungarpur, India planted 600,000 trees in 24 hours under the guidance of Indian Forestry Service which is a world record.
Reliance Group of Companies in India has the maximum number of shareholders in the world.
State Bank of India has the maximum number of branches in the world.
Dr M.C. Modi holds the world record for performing maximum eye operations @ 40 operations per hour.
With 1,300.000 active personnel and 1,800,000 reserve ones, the Indian Army is the world’s second largest army in terms of military personnel, and the largest in terms of active manpower.
The largest reflecting telescope of Asia is in Kavalur Observatory (India).It is an indigenously built 93 inch telescope.
The economy of India is the twelfth largest economy in the world by nominal value and the fourth largest by purchasing power parity (PPP).It is the world’s second-fastest growing major economy.
India has the second largest network of paved highways, after the U.S.
Nearly 49% of the high-tech start-ups in silicon Valley and Washington, D.C. are owned by Indians or Indian-Americans.
India sends more students to U.S. colleges than any country in the world. In 2004-2005, over 80,000 Indian students entered the U.S. China sent only 65,000 students during the same time.
Chess was invented in India.
Ayurveda is the earliest school of medicine known to mankind. The father of medicine, Charaka, consolidated Ayurveda 2500 years ago.
The value of "pi" was first calculated by the Indian Mathematician Budhayana, and he explained the concept of what is known as the Pythagorean Theorem. He discovered this in the 6th century, which was long before the European mathematicians.Algebra, trigonometry and calculus also orignated from India. Quadratic equations were used by Sridharacharya in the 11th century. The largest numbers the Greeks and the Romans used were 106 whereas Hindus used numbers as big as 10*53 ( i.e 10 to the power of 53 ) with specific names as early as 5000 B.C. during the Vedic period. Even today, the largest used number is Tera: 10*12( 10 to the power of 12 ).
The 'Place Value System' and the 'Decimal System' were developed in India in 100 B.C.
The game of Snakes & Ladders was created by the 13th century poet saint Gyandev. It was originally called 'Mokshapat'. The ladders in the game represented virtues and the snakes indicated vices. The game was played with cowrie shells and dices. In time, the game underwent several modifications, but its meaning remained the same, i.e. good deeds take people to heaven and evil to a cycle of re-births.
The Art of Navigation & Navigating was born in the river Sindh over 6000 years ago. The very word Navigation is derived from the Sanskrit word 'NAVGATIH'. The word navy is also derived from the Sanskrit word 'Nou'.
Bhaskaracharya rightly calculated the time taken by the earth to orbit the Sun hundreds of years before the astronomer Smart. According to his calculation, the time taken by the Earth to orbit the Sun was 365.258756484 days.
Sushruta is regarded as the Father of Surgery. Over2600 years ago Sushrata & his team conducted complicated surgeries like cataract, artificial limbs, cesareans, fractures, urinary stones, plastic surgery and brain surgeries.
Usage of anaesthesia was well known in ancient Indian medicine. Detailed knowledge of anatomy, embryology, digestion, metabolism,physiology, etiology, genetics and immunity is also found in many ancient Indian texts.
India exports software to 90 countries.
The four religions born in India - Hinduism, Buddhism, Jainism, and Sikhism, are followed by 25% of the world's population.
Islam is India's and the world's second largest religion.
There are 300,000 active mosques in India, more than in any other country, including the Muslim world.
Jews and Christians have lived continuously in India since 200 B.C. and 52 A.D. respectively
The largest religious building in the world is Angkor Wat, a Hindu Temple in Cambodia built at the end of the 11th century.
The Vishnu Temple in the city of Tirupathi built in the 10th century, is the world's largest religious pilgrimage destination. Larger than either Rome or Mecca, an average of 30,000 visitors donate $6 million (US) to the temple everyday.
Varanasi, also known as Benaras, was called "the Ancient City" when Lord Buddha visited it in 500 B.C., and is the oldest, continuously inhabited city in the world today.
India is the largest democracy in the world, the 7th largest Country in the world, and one of the most ancient civilizations.
India provides safety for more than 300,000 refugees originally from Sri Lanka, Tibet, Bhutan, Afghanistan and Bangladesh, who escaped to flee religious and political persecution.
Martial Arts were first created in India, and later spread to Asia by Buddhist missionaries.
Yoga has its origins in India and has existed for over 5,000 years.
Some Interesting data
* Who is the co-founder of Sun Microsystems ?
Mr. Vinod Khosla ( Indian )
* Who is the creator of Pentium chip (90% of the today's computers run on it)?
Mr. Vinod Dham ( Indian )
*Who is the founder and creator of Hotmail (World's No. 1 web based E-Mail program)?
Mr. Sabeer Bhatia (Indian) later on sold to Microsoft.
* Who is the president of AT & T-Bell Labs (AT & T-Bell Labs is the creator of program languages such as C, C++, UNIX to name a few)?
Mr. Arun Netravalli (Indian)
*Who is the GM of Hewlett Packard ?
Mr. Rajiv Gupta (Indian)
*Who is the new MTD (Microsoft Testing Director) of Windows 2000 , responsible to iron out all initial problems?
Mr. Sanjay Tejwrika ( Indian )
* Indians are the wealthiest among all ethnic groups in America , even faring better than the whites and the natives:
There are 3.22 Millions of INDIAN s in USA ( 1.5 % of population ).
YET, 38% of doctors in USA are INDIANs.
12% scientists in USA are INDIANs.
36% of NASA scientists are INDIANs.
34% of Microsoft employees are INDIANs.
28% of IBM employees are INDIANs.
17% of INTEL scientists are INDIANs.
13% of XEROX employees are INDIANs.
Apart from these quantitative figures, qualitatively India has been the world leader in culture, ethics, religion, humanity since the very inception of humanity on earth.
Sunday, April 17, 2011
Myth 1: You Can't Reverse an HPLC Column
False. In practice, a high performance liquid chromatography (HPLC) column is packed at pressures much higher (often as much as two-fold) than its maximum operating pressure. Thus, if the proper slurry solvent was used and the time allotted for the packed bed to be stabilized, a well-packed column should be able to work in both directions. Some reasons why one would want to flow a column in the opposite direction include backflushing operations in column switching, rinsing a column with stubborn strongly sorbed sample at its entrance (a shorter pathlength than to flush the insoluble materials through the entire column length), and flushing trapped particulates to decrease pressure build-up.
There is one exception in reversing the flow of an HPLC column. If the manufacturer has used a higher porosity frit at the entrance to the column, by reversing the column it might be possible to flush particles out of the packed bed. When the column is packed at the factory, the porosity of frit at the outlet of the column must be lower than the smallest particle size of the column. For example, if the column packing has an average diameter of 5 μm and a particle size distribution of 3–7 μm, the frit used at the column exit must be less than 3 μm so that there is no possibility that particles will escape the packed bed when the column is being used. For that instance, most manufacturers choose a 2 μm frit.
Why would a manufacturer have different porosity frits at the column inlets and outlets? Simple. A higher porosity frit has fewer tendencies to plug than a lower porosity frit. A 0.5 μm frit will plug faster than a 2 μm frit. So, to prevent rapid pressure build-up and customer complaints, a manufacturer might use a more forgiving, larger porosity frit at the inlet. Usually, the column will be marked with an arrow that indicates that it should be used in one direction only. Before reversing an HPLC column, it is best to consult the column instruction sheet or check with the column manufacturer to see if the column can be reversed.
Myth 2: All C18 (L1) Columns are the Same
False. In the early days of HPLC, octadecylsilane (most often referred to as an ODS or C18 phase) was one of the first bonded stationary phases that became available for the new technique called "reversed-phase chromatography". It became the standard phase for reversed-phase chromatography and was quickly adopted by most practitioners. Because the pharmaceutical industry was an early adopter of HPLC and regulatory bodies did not want to bless a particular manufacturer's brand of column, the Food and Drug Administration (FDA) and the US Pharmacopeia (USP) developed a classification system that gave a generic designation for each new method that was submitted under a new drug application. For HPLC columns, an "L" designation was given and because C18 was used in a majority of the submittals, it became "L1". As additional phases were added, they were given their own "L" number (for example, L7 C8, L10 CN, L11 Phenyl and so forth).
Unfortunately, this designation system proved to be unreliable because each commercial C18 column was synthesized differently using silica gel as the base material and the resulting reversed-phase columns had different properties. For example, some manufacturers used octadecylmonochlorosilane and a low surface area silica gel (Figure 1) while others used the same silane but bonded it to a higher surface area silica gel. These two C18 columns would behave differently with the latter having more C18 phase than the former. A lower coverage bonded phase sometimes had unreacted silanols that caused mixed retention mechanisms. Some manufacturers use di- and trichlorosilanes and polymerized the bonded phase to form a thicker layer with different diffusional properties. To cut down on unreacted silanols that remained after the bonding process, some manufacturers endcap these silanols with a small silane (for example, trimethylmonochlorosilane). Silanols are sometimes responsible for tailing of basic compounds at intermediate pH values. Some manufacturers even went further and double-endcapped with a second small silane to provide a more inert surface. Some manufacturers used polymeric based materials and then bonded C18 moieties to their surface resulting in a totally different C18 packing material, yet it was still considered an "L1". Others use organoalkoxysilanes that display a different degree of reactivity and can produce a slightly different C18 bonded phase than an organochlorosilane reagent would.
So, the statement "a C18 is not a C18 is not a C18" holds true even today. All C18 phases are not alike and the user should make sure that once a method is developed, he or she sticks with the same column part number to ensure rugged and robust methods. In recent times, Dolan and Snyder have studied a large number of C18 phases in an attempt to determine which phases have similar retention and selectivity features.1,2 By characterizing the phases based upon probes with as many as five retention parameters, they have classified phases with a numerical value so that one might be able to choose the closest phase in performance characteristics in case the original phase is not available from a particular manufacturer. Their approach also allows one to find a C18 phase totally unlike their existing phase that can aid in column selection during method development.
Myth 3: Guard Columns Do Not Affect a Separation
False. First of all, having a guard column is a good idea. However, the choice of a guard column can have a great effect on a separation if the wrong configuration or phase is chosen. Remember, the purpose of a guard column is to protect the analytical column against fouling by highly retained sample components, particulates and other undesirable materials. The guard column is much less expensive than the analytical column that it protects. Thus, it can be replaced more often rather than the more expensive analytical column.
Ideally, the guard column chosen should have the exact same stationary phase as used in the analytical column. If the phase is more retentive (for example, has a greater carbon loading or is a mixed-mode phase), then it can affect the separation in a detrimental manner by causing retention time shifts or even selectivity differences. If the phase is less retentive, it might or might not cause a problem unless the phase chosen impacts the overall selectivity.
For the guard column to have minimal impact on separation performance, it must be properly plumbed into the flow stream. Obviously, the guard column is inserted between the injector and the analytical column but if too much connecting tubing (either too long or two large of an internal diameter) is used, extracolumn band spreading can occur that can affect the overall separation. Systems employing integrated guard columns where the guard column literally butts up against the analytical column would offer the best solution. However, integrated guard columns are usually associated with cartridge column systems, which seem to have come into disfavour. Whatever the configuration, the guard column should be able to be removed easily and replaced from the HPLC system without affecting its operation.
Theoretically, if the guard column is adding additional column length to the analytical column, there should be additional plates generated that should increase the chromatographic resolution. However, because of some of the factors discussed previously, often the addition of a guard column just maintains the separation at best and sometimes detracts from it at worst. The advantage of the guard column is increasing column life and not necessarily increasing the overall efficiency.
Myth 4: High Temperature Always Leads to Better Separations
False. As the temperature increases, the viscosity of the mobile phase decreases and, therefore, the rate of solute mass transfer should increase thereby offering better chromatographic efficiency. True, but besides the column efficiency term (H), temperature can also affect the retention factor (k) and selectivity (α). The impact on these terms can result in improved resolution (which is really what we are concerned about in chromatography) or detract from it. Retention usually decreases as the temperature increases because, being a thermodynamic parameter, the analyte prefers to remain in the mobile phase and are eluted sooner from the column. However, different chemical species might have different degrees of change in their retention versus temperature. Stated more correctly, their van't Hoff plots (ln k vs 1/T where the temperature T is measured in kelvins) might display different slopes; in other words, their α values can change. In addition, high temperature can cause a low k peak to be eluted so quickly that it can be eluted at or near t0, the unretained peak retention time, and, therefore, be difficult to quantify.
Take the example of analgesics shown in Figure 2. This series of chromatograms shows the separation of seven analgesics at column temperatures of 20–90 °C. One can note several features of the chromatograms. First, the retention of all peaks is decreased with higher temperatures and the peaks do become narrower indicating improved efficiency. Second, one of the analgesic compounds, salicylic acid, has a much greater retention change with temperature relative to peaks 5 and 6, the closest eluted compounds. In fact, the elution order is reversed after increasing the temperature from 20 to 40 °C. At the intermediate 30 °C temperature, the salicylic acid and peak number 6, phenacetin, are coeluted. So in this instance, temperatures greater than 40 °C resulted in a shorter separation time for the entire separation yet the elution order was changed from the lower temperatures.
Of course, a side benefit of operating at higher temperature is the decrease in column operating pressure that allows one to use higher flow-rates or smaller particles.
Another experimental parameter that can cause column performance problems at higher temperature is the possible thermal mismatch of the incoming mobile phase. For example, if the column is heated to 60 °C and the incoming solvent is at room temperature, the incoming cooler solvent can cause peaks to be distorted because of the differences in the temperature that the solutes can experience in the initial part of the column. It is recommended that one preheats the mobile phase when using higher column temperatures.
Myth 5: The Higher the Carbon Load the Better the Reversed-Phase Column
False. There appears to be misconceptions about the role of chain length, carbon loading, surface coverage, and so forth when it comes to the popular alkyl-bonded phases. In general, for a truly reversed-phase mechanism where retention is based upon the relative hydrophobicities of analyte molecules, retention is usually based upon the carbon load. The higher the carbon load, the more the retention. Carbon load can be proportional to the chain length but not necessarily so. A typical silica gel has about 8.0 μmol/m2 of reactive silanols that are used for bonding organosilane reagents. If, for example, for a given surface coverage of a monolayer bonded phase in micromoles per metre squared, the longer the chain length, the more carbon would be present and, therefore, retention would be proportional to chain length. However, if a shorter chain bonded phase (say, a C8) had a higher surface coverage resulting in more carbon on the surface, then it could have more retention than a C18 bonded phase. In addition, some manufacturers use di- and trichloro-organosilanes where polymerization is used to increase the phase coverage; a shorter chain length polymeric phase could conceivably have a much greater coverage than a longer chain monomeric phase. Sometimes these polymeric phases have a thicker layer of the bonded phase that results in poorer stationary phase mass transfer than for a monomeric phase.
Very highly loaded reversed-phase columns are also prone to phase collapse or more correctly stationary phase dewetting.3 For such columns, when the amount of organic modifier falls below 10% in an aqueous environment, these "oil-like" hydrophobic phases tend to prefer to self-associate rather than being in a polar aqueous solution (that is, like prefers like). So, in this situation, having a high carbon load might be detrimental to successful reversed-phase chromatography and reproducible retention time.
Myth 6: One Always Gets More Efficiency Using a Column Packed with Smaller Particles
False. Although, for a well-packed column, the efficiency increases as the average diameter of the particles in a packed column decreases, if the extracolumn contributions to band broadening of a particular HPLC hardware system are sufficiently high then the full performance of this column will not be realized. Extracolumn contributions consist of all the additional volume outside of the packing itself. These contributions include the following volumes:
Injection volume including the loop size as well as the additional volume within the injection valve.
Tubing volume from the injector outlet to the column inlet.
Guard column interstitial volume including endfittings (if present).
In-line filter volume (if present).
The internal volume within the inlet column fitting including porous frit and flow channels.
The interstitial column volume.
The internal volume within the bottom column fitting including porous frit and flow channels.
Tubing volume from the column outlet to the detector inlet.
Tubing volume within the detector before the flowcell.
The variances of all of these volumes are additive. Thus, one can minimize injection volume and keep the column inlet tubing of short length and small internal diameter but if there is a 1 m piece of 0.20 in. connecting tubing from the column outlet to the detector, then the band broadening might be large enough to effect the overall efficiency of the separation. So, make sure that the extracolumn effects are minimized if you expect to get the expected efficiency of a sub-2 μm HPLC column or a 1.0 mm i.d. microbore column.
Myth 7: For Silica Gel Packings, Residual Silanols Are Responsible for Tailing
False. Under certain circumstances, silanols, present on all silica-based bonded phase columns, can cause tailing, especially with basic compounds. This tailing is ascribed to the fact that the silanol group is a weak acid with a pKa of approximately 4.5–4.7. Thus, as the pH of the mobile phase approaches the 4–5 range the silanol becomes ionized and can interact with positively charged molecules, such as a protonated amine, by electrostatic attractions. This interaction can be minimized by suppressing the ionization of the silanol by lowering the pH to less than 3. For some basic compounds, tailing can sometimes occur at lower pH values. There are specialized reversed-phase packings that are especially designed to provide good peak shape for basic compounds.
There are three basic causes of peak tailing: chemistry problems (one of which was discussed previously); column packing problems; and instrument hardware problems. All three can cause peak tailing and one must investigate the root causes to determine a remedy. It is outside the scope of this question to explore all three in detail but a few examples of each type will give you the general idea. First, in addition to interaction with silanols, chemistry-related tailing problems can manifest themselves in several ways. Metal chelating compounds can interact with trace metals in the column packing and this was particularly noticeable for older silica materials. Employing the wrong injection solvent can sometimes lead to tailing. Injecting the sample with a much stronger solvent than the mobile phase can give peak distortion. Tailing can result from built-up material from strongly retained sample components or mobile phase impurities at the head of the column. This material can act as a different stationary phase, causing tailing problems for compounds that interact. On occasion, mixed modes can occur thereby causing tailing. Here solutes can interact by reversed-phase and ionic interaction with active groups. Sometimes, when the mobile phase pH is wrong and samples are partially ionized, the resulting peaks can be distorted and resemble tailing. A small partially coeluted peak on the backside of a larger peak can sometimes look like tailing.
Column packing problems can cause peak tailing. A void at the head of a column can lead to doublet peaks or peak tailing. Columns that are not well packed can have channelling resulting in bad peak shape. If the column is overloaded by too great of a sample mass, tailing can occur, although peak fronting is more prevalent. At low injection masses, tailing can occur by overloading silanols.
Let us consider a few instrumentation and hardware problems that might show up as tailing. Tailing can be caused by extracolumn effects and other unswept volumes in the flow lines. Unswept volumes from an endfitting or an improper connection can manifest itself as peak tailing. Pressure pulses from the injector can cause column voids that can give rise to tailing. A slow detector time constant with quickly eluted peaks can give peak broadening sometimes resembling tailing. Thermal mismatch between the incoming solvent at room temperature and a high column operating temperature can also cause peak distortion.
So, it is not always the silanols that cause peak tailing in HPLC.
Myth 8: Silica Gel–Based Packings Can Be Used Only From pH 2 to 7
False. Generally, there are two mechanisms of chemical deterioration of an HPLC reversed-phase column: catalysed hydrolysis of siloxane bonds at pH less than 2; and dissolution of the silica gel by hydroxide ion at pH values greater than 7–8. These two phenomena have been extensively studied by Kirkland and coworkers.5–7 At pH values less than 2, the –Si-O-Si- (siloxane) bond can be attacked by hydronium ion (H3O+ ) cleaving the bonded phase, which results in a loss of organic. With time, retention will usually decrease as the carbon content is reduced. It is especially noticeable with the short chain endcapping moieties such as trimethylsilane. The longer chain C18 phases offer some protection of the underlying siloxane by virtue of their steric hindrance but eventually even these will be attacked, especially if the temperature is higher than ambient. There are sterically protected and densely coated bonded phases that help to impede the cleavage of bonded phases on silica gel. Polymeric phases do not show this instability but have the disadvantage of lower efficiency than silica-based phases.
On the high pH side, there must be some way to block the underlying silica gel from attack by hydroxide ion. Once the dissolution process occurs, the column will eventually fail, often developing a void. Speciality columns are made for high pH operation including bidentate C18, hybrid and polymer-coated silica. These phases chemically protect the base material from hydroxide attack. These packings are capable of withstanding pH values in the 11–12 range. High temperatures should be avoided with most silica-based packings when operating in this range. Of course, polymeric phases can be operated at pH values as high as 13, sometimes even 14, but, as pointed out previously, they have the disadvantage of lower efficiency than silica-based phases.
So, the real answer: special silica-gel bonded phases can operate outside of the pH 2–7 window but care should be exercised with regular silica gel-based packings, especially at high temperature.
Myth 9: Modern HPLC Columns Should Withstand at Least 1000 Injections
False. There are a number of factors that control the number of injections any modern HPLC column can withstand. Some of the factors are based upon the mode: reversed phase, ion exchange, size exclusion, normal phase, chiral, hydrophilic interation and so forth. Some of these factors are based upon the type of packing in the column — silica gel-, hybrid-, zirconia-, or polymeric-based packings or a soft gel or degree of crosslinking of resin. Some factors are based upon the phase itself: coverage, type of bond, polymeric, monolayer, or coated phase. Other factors are based upon the operating conditions: pH, temperature, mobile phase constituents, buffer composition, flow-rate, pressure and so on. Still other factors are based upon the sample that is injected: standards only, sample cleanliness, sample pH, sample volume, sample impurities present, solute molecules themselves and so on.
If a column is abused such as by using it outside of its recommended pH limits or flow-rate range, it might only yield 50 injections or even less. If the sample is simple with no highly retained impurities, then the column might withstand 5000 injections or more. If the column is not continuously operated at its upper limit, it will live longer. If the column is subjected to a variety of samples and never flushed to remove strongly retained impurities, then its life will be shortened.
In the author's experience of visiting many pharmaceutical companies, most of them expect at least 1000 injections out of a 5 μm reversed-phase column when it is used for analysing formulations, simple drug mixtures and standards. If the column is used for "dirty samples" such as biological fluid extracts or environmental extracts that have not been exhaustively cleaned up, then one should not expect 1000 injections.
So, the number of injections expected is not cut and dry but is highly dependent upon the type of column, operating conditions, sample cleanliness and degree of abuse. Of course, with guard columns and, perhaps, in-line filters, column life should be longer. In informal polling of audiences during numerous seminars by the author, a small percentage (less than 15%) of the users actually track the number of injections for a given column. So, many chromatographers don't really know how many injections that they get per column lifetime. Some modern HPLC instruments have built-in column modules and software that permits one to monitor the injection number.
Myth 10: Columns Always Should Be Capped Tightly to Prevent Packing Damage from Contact with the Atmosphere
False. In general, the tiny hole in the endfitting, which is probably not bigger than 0.02 in. in diameter, has such a small cross-sectional area that damage to the column resulting from air coming in to contact with the packing and the solvent inside the column evaporating is minimal. Even if a small amount of air entered the column, it would probably have a hard time diffusing through the microparticulate packed bed and coming in to contact with enough packing material to cause detrimental effects. If there was a small amount of air in the column, as soon as it was pressurized when it was next installed into the HPLC instrument and mobile phase pumped through it, the small amount of air would probably dissolve at high pressure or be flushed out in the initial fluid in a short time and not cause any problems with later use. However, if you would feel more secure by capping the endfittings by all means do so. Most columns come equipped with male compression fitting caps that can be tightened to prevent any possibility of storage solvent evaporation or air entering the packed bed.
Sai Baba of Shirdi (September 28, 1838 – October 15, 1918), also known as Shirdi Sai Baba (Marathi: शिर्डीचे श्री साईबाबा,Urdu: شردی سائیں بابا), was an Indian guru, yogi, and fakir who is regarded by his Hindu and Muslim devotees as a saint. Hindu devotees consider him an incarnation of Lord Dattatreya. Many devotees believe that he was a Sadguru, an enlightened Sufi Pir (Urdu: پیر), or a Qutub. He is a well-known figure in many parts of the world, but especially in India, where he is much revered.
Teachings and practices
Sai Baba opposed all persecution based on religion or caste. He was an opponent of religious orthodoxy - Christain, Hindu and Muslim. Although Sai Baba himself led the life of an ascetic, he advised his followers to lead an ordinary family life.
Sai Baba encouraged his devotees to pray, chant God's name, and read holy scriptures. He told Muslims to study the Qur'an, and Hindus to study texts such as the Ramayana, Vishnu Sahasranam, Bhagavad Gita, and Yoga Vasistha. He advised his devotees and followers to lead a moral life, help others, love every living being without any discrimination, and develop two important features of character: faith (Shraddha) and patience (Saburi). He criticized atheism. In his teachings, Sai Baba emphasized the importance of performing one's duties without attachment to earthly matters, and of being content regardless of the situation.
Sai Baba interpreted the religious texts of both Islam and Hinduism. He explained the meaning of the Hindu scriptures in the spirit of Advaita Vedanta. His philosophy also had numerous elements of bhakti. The three main Hindu spiritual paths - Bhakti Yoga, Jnana Yoga, and Karma Yoga - influenced his teachings.
Sai Baba said that God penetrates every thing and every being. He emphasized the complete oneness of God which was very close to the Islamic tawhid and the Hindu doctrine of the Upanishads. Sai Baba said that the world is transient, and that only God and his gifts are eternal. He emphasized the importance of devotion to God - bhakti - and surrender to his will. He also talked about the need of faith and devotion to one's spiritual guru. He said that everyone was the soul and not the body. He advised his followers to develop a virtuous character, and taught them that all fate was determined by karma.
Sai Baba left no written works. His teachings were typically short, pithy sayings rather than elaborate discourses. Sai Baba would ask his followers for money (dakshina), some of which he would give to the poor and other devotees the same day, and the rest was used to buy wood to maintain Dhuni. According to his followers, this was done to rid them of greed and material attachment.
Sai Baba encouraged charity, and stressed the importance of sharing. He said: "Unless there is some relationship or connection, nobody goes anywhere. If any men or creatures come to you, do not discourteously drive them away, but receive them well and treat them with due respect. Shri Hari (God) will certainly be pleased if you give water to the thirsty, bread to the hungry, clothes to the naked, and your verandah to strangers for sitting and resting. If anybody wants any money from you and you are not inclined to give, do not give, but do not bark at him like a dog." Other favorite sayings of his were: "Why do you fear when I am here", and "He has no beginning... He has no end."
Sai Baba made eleven assurances to his devotees:.
- Whosoever puts their feet on Shirdi soil, their sufferings will come to an end.
- The wretched and miserable will rise to joy and happiness as soon as they climb the steps of the mosque Dwarakamayi.
- I shall be ever active and vigorous even after leaving this earthly body.
- My tomb shall bless and speak to the needs of my devotees.
- I shall be active and vigorous even from my tomb.
- My mortal remains will speak from my tomb.
- I am ever living to help and guide all who come to me, who surrender to me, and who seek refuge in me.
- If you look at me, I look at you.
- If you cast your burden on me, I shall surely bear it.
- If you seek my advice and help, it shall be given to you at once.
- There shall be no want in the house of my devotee.
Sāī is of Sanskrit origin, meaning "Sakshat Eshwar" or the divine. The honorific "Baba" means "father; grandfather; old man; sir" in Indo-Aryan languages. Thus Sai Baba denotes "holy father" or "saintly father".
His parentage, birth details, and life before the age of sixteen are obscure, which has led to speculation about his origins.
Sai Baba had no love for perishable things and his sole concern was self-realization. He remains a very popular saint, and is worshipped by people around the world. He taught a moral code of love, forgiveness, helping others, charity, contentment, inner peace, and devotion to God and guru. Sai Baba's teaching combined elements of Hinduism and Islam: he gave the Hindu name Dwarakamayito the mosque he lived in, practiced Hindu and Muslim rituals, taught using words and figures that drew from both traditions, and was buried in a Hindu temple in Shirdi. One of his well known epigrams, "Sabka Malik Ek " ("One God governs all"), is associated with both the Bhagavad-Gita and Sufism. He always uttered "Allah Malik" ("God is King").
Though the debate over his Hindu or Muslim origins continues, many of his practices point more to his being a Muslim believing in the unity of God, reciting Al-Fatiha and other Qur'anic readings at Muslim festival times, listening to hamds and qawwali twice daily, practicing Salah (Namaz), wearing clothing reminiscent of a Sufi fakir, eating meat, and abstaining from alcohol. A mosque still stands in Shirdi, a place in which he once lived and continued to visit regularly. According to Purdom, when Kulkarni Maharaj requested Upasni Maharaj to pay a visit to Sai Baba, Upasni replied 'Why should I go to a Muslim?'
Sai Baba is revered by several notable Hindu and Sufi religious leaders. Some of his disciples became famous as spiritual figures and saints, such as Upasni Maharaj, Saint Bidkar Maharaj, Saint Gangagir, Saint Jankidas Maharaj, and Sati Godavari Mataji.
Historians and devotees agree that there is no reliable evidence for a particular birthplace or date of birth. Various communities have claimed that he belongs to them, but nothing has been substantiated. many historians support this finding. It is known that he spent considerable periods with fakirs, and his attire resembled that of a Muslim fakir. Baba reportedly arrived at the village of Shirdi in the Ahmednagar district of Maharashtra, India, when he was about 16 years old. It is generally accepted that Sai Baba stayed in Shirdi for three years, disappeared for a year, and returned permanently around 1858, which suggests a birth year of 1838.
Sai Baba led an ascetic life, sitting motionless under a neem tree and meditating while sitting in an asana. The Shri Sai Satcharita recounts the reaction of the villagers:
The people of the village were wonder-struck to see such a young lad practicing hard penance, not minding heat or cold. By day he associated with no one, by night he was afraid of nobody.
His presence attracted the curiosity of the villagers, and he was regularly visited by the religiously inclined, including Mhalsapati, Appa Jogle and Kashinatha. Some considered him mad and threw stones at him. Sai Baba left the village, and little is known about him after that. However, there are some indications that he met with many saints and fakirs, and worked as a weaver. He claimed to have fought with the army of Rani Lakshmibai of Jhansi during the Indian Rebellion of 1857.
Return to Shirdi
In 1858 Sai Baba returned to Shirdi. Around this time he adopted his famous style of dress consisting of a knee-length one-piece robe (kafni) and a cloth cap. Ramgir Bua, a devotee, testified that Sai Baba was dressed like an athlete and sported 'long hair flowing down to the end of his spine' when he arrived in Shirdi, and that he never had his head shaved. It was only after Baba forfeited a wrestling match with one Mohdin Tamboli that he took up the kafni and cloth cap, articles of typical Sufi clothing.This attire contributed to Baba's identification as a Muslim fakir, and was a reason for initial indifference and hostility against him in a predominantly Hindu village. According to B.V. Narasimhaswami, a posthumous follower who was widely praised as Sai Baba's "apostle", this attitude was prevalent up to 1954 even among some of his devotees in Shirdi.
For four to five years Baba lived under a neem tree, and often wandered for long periods in the jungle around Shirdi. His manner was said to be withdrawn and uncommunicative as he undertook long periods of meditation. He was eventually persuaded to take up residence in an old and dilapidated mosque and lived a solitary life there, surviving by begging for alms, and receiving itinerant Hindu or Muslim visitors. In the mosque he maintained a sacred fire which is referred to as a dhuni, from which he gave sacred ashes ('Udhi') to his guests before they left. The ash was believed to have healing and apotropaic powers. He performed the function of a local hakim, and treated the sick by application of ashes. Sai Baba also delivered spiritual teachings to his visitors, recommending the reading of sacred Hindu texts along with the Qur'an. He insisted on the indispensability of the unbroken remembrance of God's name (dhikr, japa), and often expressed himself in a cryptic manner with the use of parables, symbols and allegories.
Sai Baba participated in religious festivals and was also in the habit of preparing food for his visitors, which he distributed to them as prasad. Sai Baba's entertainment was dancing and singing religious songs. His behavior was sometimes uncouth and violent.
After 1910 Sai Baba's fame began to spread in Mumbai. Numerous people started visiting him, because they regarded him as a saint with the power of performing miracles, or even as an Avatar. They built his first temple at Bhivpuri, Karjat
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