Category: Chemistry

Researchers in Argentina have developed a new approach to testing food packaging for trace amounts of the toxic heavy metal cadmium.

Cadmium is one of several additives used extensively in the manufacture of plastics. Regulations limit the concentration of cadmium allowable, of course. In the European Union that limit is 100 milligrams per kilogram. But, the toxic metal has a long biological half-life (10 to 30 years) and so essentially accumulates in your body on repeated exposure.

Analytical advances aside, I asked Rodolfo Wuilloud of LISAMEN, how big a problem is cadmium in food packaging? Should the public be concerned?

“The presence of heavy metals in plastic food packaging is an important problem considering the extended use of this type of packaging,” he told me, “Concentration of heavy metals should be limited in order to reduce their potential health impact resulting from their possible migration from the packaging material into food and also to ensure that such substances are not released into the environment, for example in emissions or ash when packaging is incinerated, or in leachate when packaging is landfilled.”

He adds, that it is important that the public should be aware of this problem. Concern is the first step towards getting governments to change environmental policies. “It is necessary to introduce national measures to ensure that packaging is allowed on the market only if it complies with certain requirements in their composition so as to prevent the addition of noxious heavy metals to packaging and to reduce the impacts on the environment and human health,” Wuilloud’s colleague Estefania Martinis says.

The team used room temperature ionic liquids (RTILs) as an online pre-concentration medium for flame atomic absorption spectrometry analysis of trace cadmium in plastic food packaging materials. Critically, the use of non-volatile, non-flammable RTILs instead of volatile and flammable organic solvents is helping in this regard by allowing analytical scientists to breathe new life into powerful techniques, such as atomic absorption spectroscopy, that have been labelled “old fashioned” in recent years as other methods emerged.

Martinis, E., Olsina, R., Altamirano, J., & Wuilloud, R. (2009). On-line ionic liquid-based preconcentration system coupled to flame atomic absorption spectrometry for trace cadmium determination in plastic food packaging materials Talanta, 78 (3), 857-862 DOI: 10.1016/j.talanta.2008.12.051

This week, it’s my The Alchemist chemistry news column that coincides with SpectroscopyNOW updates:

The Alchemist this week catches site through his spyglass of complex interstellar molecules with a hint of raspberry and rum, and a possible way to capture carbon usefully that doesn’t require huge energy input. Geordie scientists have discovered why a breakfast fry-up could be the optimal hangover cure, a NIST team has found a way to suppress quantum errors, and flexible concrete that heals itself has been made by US materials scientists. Finally, the publicity department at the Royal Society of Chemistry could strike gold in a major PR awards thanks to its Italian Job.

Recycling carbon dioxide – A research team in Singapore has developed an alternative to simply burying carbon dioxide captured from sources such as coal-fired power stations. Their experiments used NMR spectroscopy to track the catalytic conversion of carbon dioxide into methanol under very mild reaction conditions. (Personally, I think these kinds of efforts will never likely balance the energy/resources books and will always come out costing more than they save in terms of emissions and fuel, but an interesting reaction, nevertheless).

ELISA, meet SERRS – Surface-enhanced resonance Raman scattering could be used to quickly spot the telltale signs of prostate cancer at the molecular level, according to a British team. This is the first use of a well-known ELISA colorimetric substrate as a SERRS marker.

Polymerising phosphates – X-ray crystallography has been used to identify a novel enzyme that polymerises the essential biochemical building block phosphate in eukaryotes, which include all animals, plants, fungi, and protists. The proof of principle was obtained with yeast and could pave the way to the discovery of related enzymes in other species.

Raspberries and ultraviolet skin damage – There’s no connection between the interstellar molecules mentioned earlier that just happen to taste of raspberries and this news item about how ellagic acid found in lots of different types of fruit and vegetables can protect skin cells from the aging effects of UV-B. Other, of course, than the fruity headlines the research makes possible.

Researchers in Korea have demonstrated that the topical application of antioxidant ellagic acid, which is found in certain fruits and berries, can protect against damage to the skin caused by incident ultraviolet-B radiation. Their work suggests that the compound could help protect people to some extent from the skin-aging effects of the sun.

Avoiding scanners – Efforts should be made to avoid unnecessary patient exposure to imaging devices that use ionising radiation, according to a warning from the International Atomic Energy Agency. The Agency suggests that MRI and ultrasound should therefore be more widely used instead of X-ray based imaging.

I was offline with my family last week, walking and drinking ale in Derbyshire, so I’m a bit late in alerting you to my latest news stories on SpectroscopyNOW, they went live in my absence. So here’s the catchup:

Tyson’s toxic technique – The first accurate test for arsenic compounds in contaminated soil has been developed by US chemists. Their atomic emission approach to the problem could provide improved environmental and health assessments of contaminated sites.

Cosmic X-rays – Dutch have astronomers have, for the first time, used X-ray spectroscopy to reveal the long-sought signatures of dust in the interstellar medium, the extended X-ray absorption fine structure (EXAFS).

ET’s aminos – One of biology’s unanswered questions involves the evolution of the genetic code and the fact it uses just 20 natural amino acids as its building blocks for making proteins. A mathematical analysis of biochemistry by researchers in Canada suggests a possible answer that could have profound implications for our search for life on other planets.

Teasing with a stripline – A high-resolution NMR flow probe for microfluidic systems based on a new type of stripline detector chip has been developed by researchers in The Netherlands. The tool could be useful in direct monitoring of chemical reactions performed in so-called lab-on-a-chip devices.