Wednesday, August 28, 2013

Periodic Table | Free Poster Download | Greyhound Chromatography

Download a free A3 Poster of the Periodic Table.

The periodic table of the chemical elements (also periodic table of the elements) is a tabular display of the chemical elements. Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869, who intended the table to illustrate recurring periodic trends in the properties of the elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behaviour.

Over 70 single element standards of the Periodic Table are available from High Purity Inc; supplied by Greyhound Chromatography and Allied Chemicals. Concentrations include both 1000 and 10.00 in aqueous solution, (unless otherwise noted). Most standards are packaged in 50,100, 250 and 500 mL HDPE or LDPE laboratory grade bottles. The density is provided on the Certificate of Analysis as additional information for the user.  Customised mixtures can be made to the customers specific requirements.  Reference Standards are supplied to Guide 34.

The accuracy of all standards is verified against NIST Spectrometric Standard Solutions. A certificate of Analysis and Safety Data Sheet are included with each standard. Standards are certified accurate for a period of 18 months from the date of shipment unless stated otherwise on the Certificate of Analysis.

The periodic table is now ubiquitous within the academic discipline of chemistry, providing a useful framework to classify, systematise, and compare all of the many different forms of chemical behaviour. The table has found many applications in chemistry, physics, biology, and engineering, especially chemical engineering.

In 1789, Antoine Lavoisier published a list of 33 chemical elements. Although Lavoisier grouped the elements into gases, metals, non-metals, and earths, chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads (groups of three) based on their chemical properties.Lithium, sodium, and potassium, for example, were grouped together as being soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third. This became known as the Law of triads. German chemist Leopold Gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. Jean Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all.

German chemist August Kekulé had observed in 1858 that carbon has a tendency to bond with other elements in a ratio of one to four. Methane, for example, has one carbon atom and four hydrogen atoms. This concept eventually became known as valency. In 1864, fellow German chemist Julius Lothar Meyer published a table of the 49 known elements arranged by valency. The table revealed that elements with similar properties often shared the same valency.

Of the 94 naturally occurring elements, those with atomic numbers 1 through 40 are all considered to be stable isotopes. Elements with atomic numbers 41 through 82 are apparently stable (except technetium and promethium) but theoretically unstable, or radioactive. The half lives of elements 41 through 82 are so long however that their radioactive decay has yet to be detected by experiment. These theoretical radionuclides have half lives at least 100 million times longer than the estimated age of the universe. Elements with atomic numbers 83 through 94 are unstable to the point that their radioactive decay can be detected. Some of these elements, notably thorium (atomic number 90) and uranium (atomic number 92), have one or more isotopes with half lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced the heavy elements before the formation of our solar system. For example, at over 1.9×1019 years, over a billion times longer than the current estimated age of the universe, bismuth-209 (atomic number 83) has the longest known alpha decay half life of any naturally occurring element. The very heaviest elements (those beyond plutonium, atomic number 94) undergo radioactive decay with half lives so short that they have only been observed as the result of experimental observation.

Apart from the hydrogen and helium in the universe, which are thought to have been mostly produced in the Big Bang, the chemical elements are thought to have been produced by one of two later processes—either cosmic ray spallation (important for lithium, beryllium and boron), or stellar nucleosynthesis (which produces all elements heavier than boron). Oxygen is the most abundant element in the Earth's crust, making up almost half of its mass Relatively small amounts of elements continue to be produced on Earth as products of natural transmutation processes. This includes production by cosmic rays or other nuclear reactions (see cosmogenic and nucleogenic nuclides), or as decay products of long-lived primordial nuclides.

English chemist John Newlands produced a series of papers in 1864 and 1865 that described his own classification of the elements: he noted that when listed in order of increasing atomic weight, similar physical and chemical properties recurred at intervals of eight, which he likened to the octaves of music. This law of octaves, however, was ridiculed by his contemporaries and the Chemical Society refused to publish his work. Nonetheless, Newlands was able to draft an atomic table and use it to predict the existence of missing elements, such as germanium.

Russian chemistry professor Dmitri Ivanovich Mendeleev and Julius Lothar Meyer independently published their periodic tables in 1869 and 1870, respectively. They both constructed their tables in a similar manner: by listing the elements in a row or column in order of atomic weight and starting a new row or column when the characteristics of the elements began to repeat. The success of Mendeleev's table came from two decisions he made: The first was to leave gaps in the table when it seemed that the corresponding element had not yet been discovered. Mendeleev was not the first chemist to do so, but he was the first to be recognised as using the trends in his periodic table to predict the properties of those missing elements, such as gallium and germanium.

The second decision was to occasionally ignore the order suggested by the atomic weights and switch adjacent elements, such as cobalt and nickel, to better classify them into chemical families. With the development of theories of atomic structure, it became apparent that Mendeleev had listed the elements in order of increasing atomic number.

New elements have been proposed in recent years; Scientists have put forward their suggested names for the newest additions to the Periodic Table.

If the names are accepted, element 114 will become Flerovium (Fl) in honour of the physicist Georgiy Flerov.While element 116 will become Livermorium (Lv), after the Californian laboratory where it was discovered.The table's governing body will officially endorse the names in five month's time, 10 years after the elements were discovered.The newest elements were among a handful of elements put forward for inclusion in the table in recent years. They were accredited in June this year after a three year review by the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP).The other putative heavy elements, 113, 115, and 118, are still under review.Scientists at Lawrence Livermore National Laboratory (LLNL), in collaboration with a team at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia, discovered the newest additions to the periodic table by smashing calcium ions into the element curium to create element 116, which quickly decays to element 114. The teams also created element 114 separately by replacing curium with a plutonium target.IUPAC will officially accept the proposed names after giving the public time to comment on the discoverers' choice.

Element 115 may have been discovered

Evidence for new element Ununpentium may swell Periodic Table.  The atom, which has an atomic number of 115, is one of the heaviest chemical elements detected to date and does not occur naturally.
Instead scientists had to synthesis it in the laboratory by bombarding a film of another heavy element known as americium with calcium ions.

The resulting element lasted for just a fraction of a second before it decaying into more commonly found elements.
Although it has yet to be officially named, Element 115 has the temporary name of ununpentium.
Conspiracy theorists have in the past claimed that ununpentium was part of technology used by UFOs and it has also featured heavily in computer games as a source for weapons. 

However, in reality the uses for the new element, which is highly unstable and so short lived, are likely to be extremely limited.
The new findings must now be assessed by a panel of international experts who will decide whether it can be included in the periodic table.  Ununpentium is one of a number of elements that were theoretically thought to exist.
It was first created in 2004 by a team of Russian and American scientists but the evidence was deemed insufficient for it to be officially classified as a new element.

The latest experiments to prove the existence of Element 115 were conducted at Lund University in Sweden.
Professor Dirk Rudolph, who led the work at the division of atomic physics at Lund University, said he hoped it would now allow the element to be included in the periodic table.

Their findings are published in the journal Physical Review Letters.
He said: "This was a very successful experiment and is one of the most important in the field in recent years.
"There are three isotopes of element 115 thought to be known or observed: Those with 172, 173, and 174 neutrons in the nucleus - 287-115, 288-115 and 289-115.  "Based on the data from the 288-115 nuclei, this isotope has a half-life of 160 milliseconds."
The researchers were able to detect Element 115 by looking for a distinctive fingerprint in the X-ray radiation it gave off.
New elements are assessed by members of the International Union of Pure and Applied Chemistry and the International Union of Pure and Applied Physics.
In 2011 they approved the names of three new elements that have the atomic numbers 110, 111 and 112. These were named darmstadtium (Ds), roentgenium (Rg) and copernicium (Cn).
The most recently approved element was Livermorium, which has the atomic number 116 and had its name adopted in May 2012.

(Source: Element 115 : Daily Telegraph 28th August 2013)

More about Lithium on wikipedia

Tuesday, August 27, 2013

Bisphenol A Reference Standards available from Wellington Laboratories

Wellington Laboratories Devlop Native and Mass-labelled Standards of  Bisphenol A                   

Bisphenol A (BPA) is a high production volume chemical with over 8 billion pounds being produced on a global scale annually. Its use in polycarbonate plastics and epoxy resins has resulted in its incorporation into a vast number of consumer products. Concerns have been raised regarding the leaching of residual BPA from packaging and storage containers into food and beverages due to its reported endocrine disrupting effects.

There have been many studies whose findings have been reported widely. One study links phthalates to increased insulin resistance in children, while another associates bisphenol A (BPA) with high body-mass index (BMI) and expanding waistlines. Both studies appear online Aug. 19 and in the September print issue of Pediatrics.

"There is increasing concern that environmental chemicals might be independent contributors to childhood diseases related to the obesity epidemic," said phthalates study author Dr. Leonardo Trasande, an associate professor of pediatrics and environmental medicine at the NYU School of Medicine. "Our research adds to these growing concerns."
Phthalates are chemicals used to soften and increase the flexibility of plastics and vinyl. They are suspected endocrine disruptors, and manufacturers have discontinued their use in baby products like teething rings and pacifiers.

The study found that insulin resistance in children increased with levels of a phthalate called di-2-ethylhexylphthalate, or DEHP. The association held even after researchers took into account the children's caloric intake, BMI and other risk factors for diabetes.

"There are lab studies suggesting these chemicals can influence how our bodies respond to glucose," Trasande said. "In particular, they are thought to influence genes that regulate release of insulin. There are other potential mechanisms, but that is the main mechanism of concern."

In the other study, researchers Dr. Donna Eng and colleagues at the University of Michigan found that high urinary levels of BPA are associated with increased risk of obesity.

BPA is used to make polycarbonate and epoxy resins for a wide variety of products. For example, aluminum cans use a BPA lining to prevent corrosion. It has been linked to a wide variety of health concerns, and the U.S. Food and Drug Administration has banned its use in sippy cups, baby bottles and infant formula packaging.

The study reviewed data on about 3,300 kids aged 6 to 18, and found that children with high BPA levels tend to have excessive amounts of body fat and unusually expanded waistlines.

Although BPA is the most widely recognised bisphenol on the market, there are a number of analogues that are currently in production to replace it. In fact, recent studies have reported the detection of Bis(4-hydroxyphenyl) sulfone (BPS) and 2,2-Bis(4-hydroxyphenyl) butane (BPB)n in canned food products. Due to the structural similarity between BPA and its analogues, it is believed that this family of compounds will exhibit similar environmental behaviour and toxicity. In order to aid researchers in the detection of BPA and BPA analogues in environmental samples, Wellington Laboratories has produced native and mass-labelled standards of Bisphenol A (BPA and MBPA respectively) as well as seven native bisphenol analogues (BPAF,BPAP,BPB,BPF,BPP,BPS, and BPZ).
Ends.

Editors notes:
Wikipedia: Bisphenol A (BPA) is a man-made carbon-based synthetic compound with the chemical formula (CH3)2C(C6H4OH)2 belonging to the group of diphenylmethane derivatives and bisphenols.
BPA is used to make certain plastics and epoxy resins; it has been in commercial use since 1957. BPA-based plastic is clear and tough, and is used to make a variety of common consumer goods (such as baby and water bottles, sports equipment, and CDs and DVDs) and for industrial purposes, like lining water pipes. Epoxy resins containing BPA are used as coatings on the inside of many food and beverage cans. It is also used in making thermal paper such as that used in sales receipts.
It is part of the bisphenols group of chemical compounds with two hydroxyphenyl functionalities. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water. Bisphenol A has a vapor pressure of 5×10−6 Pa.[1]
BPA exhibits hormone-like properties at high dosage levels that raise concern about its suitability in consumer products and food containers where exposure is orders of magnitude lower. Since 2008, several governments have investigated its safety, which prompted some retailers to withdraw polycarbonate products. A 2010 report from the United States Food and Drug Administration (FDA) identified possible hazards to fetuses, infants, and young children.[2] Since that time numerous studies performed at the National Center for Toxicological Research have been performed that addressed many of those issues.[3]
The United States FDA has removed the use of BPA in baby bottles, sippy cups and infant formula packaging based on market abandonment, not safety.[4] The European Union and Canada have banned BPA use in baby bottles.

Wellington Laboratories products are available to testing institutions worldwide and are supplied by Greyhound Chromatography and Allied Chemicals, Located in Birkenhead, UK.  Contact sales@greyhoundchrom.com for current pricing

Tuesday, August 27, 2013

Native/Mass Labelled Bisphenol A & Native Bisphenol Analogues

 Native/Mass-labelled Bisphenol A & Native Bisphenol Analogues              


Bisphenol A (BPA) is a high production volume chemical with over 8 billion pounds being produced on a global scale annually. Its use in polycarbonate platics and epoxy resins has resulted in its incorporation into a vast number of consumer products. Concerns have been raised regarding the leaching of residual BPA from packaging and storage containers into food and beverages due to its reported endocrine disrupting effects. Although BPA is the most widely recognised bisphenol on the market, there are a number of analogues that are currently in production to replace it. In fact, recent studies have reported the detection of Bis(4-hydroxyphenyl) sulfone (BPS) and 2,2-Bis(4-hydroxyphenyl) butane (BPB)n in canned food products. Due to the structural similarity between BPA and its analogues, it is believed that this family of compounds will exhibit similar environmental behaviour and toxicity. In order to aid researchers in the detection of BPA and BPA analogues in environmental samples, Wellington Laboratories has produced native and mass-labelled standards of Bisphenol A (BPA and MBPA respectively) as well as seven native bisphenol analogues (BPAF,BPAP,BPB,BPF,BPP,BPS, and BPZ).

Wellington Reporter Native/Mass-labelled Bisphenol A & Native Bisphenol Analogues 

Buy Now - call or email sales@greyhoundchrom.com for current pricing. 

Wellington Laboratories products are supplied by Greyhound Chromatography and Allied Chemicals, 6 Kelvin Park, Birkenhead, Merseyside, CH41 1LT contact sales@greyhoundchrom.com 

1 2 Next
Please wait while we search our Catalogue