Lead Researcher: Prof Andy Meharg

The Elemental Analysis facility in the Advanced Asset laboratory features ICP-MS, light stable isotope mass spectrometry, desktop XRF and Dionex. The Agilent ICP-MS is used for low-level total elemental analysis in acid/alkali digests (such as arsenic, antimony, cadmium, selenium, iodine, phosphorus, lead, copper, zinc etc.) and lead isotopes. It is coupled to Dionex to enable anion speciation, predominantly arsenic speciation, in a range of matrices such as waters, animal tissues, plants, soils and urines. The Sercon mass spectrometry is dedicated to C, N, H, S and O isotopes in solid samples including animal and plant tissues and soils. The Rigaku XRF complements the ICP-MS as it has better coverage of macro-elements (calcium, potassium, magnesium, sulphur, silicon, phosphorus) in a wide range solid samples. The standalone Dionex is used for nutrient anion and cation (nitrate, nitrite, ammonium, chloride, fluoride, phosphate, sulphate etc.) in water samples.

Examples of some our projects employing Elemental Analysis:

Rice and wheat feed the world but their cultivation is fraught with sustainability issues. A NERC Newton Fund grant has enabled to link up with other UK institutions (Sheffield & Leeds) and China (Chinese Academy of Sciences, Institute for Urban Environment) to tackle the widespread acidification of agricultural soils through the intensive use over the years of inorganic nitrogen fertilizers. Furthermore, the production of inorganic nitrogen is not sustainable as the Haber process it relies on is based on finite natural gas resources. The solution the Chinese are looking to is recycling organic wastes streams, both human and farm, to supply not only nitrogen, but also phosphorus, with global phosphorus use also not being sustainable. Organic matter will also improve soil quality in general. But there is one major issue, organic wastes tend to be elevated in toxic metals and metalloids; arsenic, cadmium, copper and lead, in particular. We use ICP-MS to speciate and quantify elements in peri-urban settings were these organic wastes are deployed, and characterize the molecular responses of plants and soil microbes to organic waste derived toxins. This work will lead to developing optimum sustainable practice for paddy management, while minimizing entry of toxins into soils and foods.

Rice is 10-fold elevated in the carcinogen inorganic arsenic compared to most other foods. The arsenic concentrations are such that rice consumption poses a threat to human health, particularly for the subsistence rice diets of Asia. Nestle Foundation funding has enabled us to explore simple, low cost, low tech and sustainable technology approaches to removing inorganic from rice in Bangladesh. Bangladeshi’s eat parboiled rice and we are looking at simple interventions in parboiling to significantly reduce inorganic arsenic in rice. Our trials show that we can remove 50% or more inorganic arsenic using such rice preparation approaches. Furthermore, this approach is centralized as most rice is parboiled in Bangladesh, enabling greatly reduced inorganic arsenic rice to be delivered for all. Our state-of-the-art ion exchange – ICP-MS facility is central to this work as it quantifies how changing parboiling parameters lowers inorganic arsenic in grain. We use ICP-MS also to quantify nutrient elements to ensure that any changes in parboiling protocol does not result in less nutritious rice. 

National Diet and Nutrition Surveys (NDNS) have revealed that some sub-groups of the population have low intakes of trace elements. Trace elements have wide roles in human biochemical and neurological function. It is not understood how the levels of trace elements in the brain change in the elderly and the majority of studies are insufficiently powered to detect any significant age-related correlations. Funded by Alzheimer’s Research UK we are ascertaining whether age-associated changes are consistent between healthy individuals and in those suffering from neurodegenerative diseases.  We have examined large numbers of brain tissue specimens from healthy elderly people, patients with Alzheimer’s disease, and patients with dementia with Lewy bodies. We have found that in the healthy elderly that there is a gradual decline in the brain levels of both copper and iron. Furthermore, we have uncovered changes in brain levels of copper, iron, sodium and potassium following the onset of severe Alzheimer’s disease. This work is identifying the trace elements most appropriate for dietary supplementations in the elderly, which perhaps could prevent cognitive decline or reduce dementia risk.