Thursday, 20 May 2010

Row for Heroes

On Wednesday 12th May 2010, two Army Doctors, Nick Dennison and Hamish Reid, set out to Row around Great Britain in order to raise money for Help for Heroes and the Army Benevolent Fund. In doing so they will enter the record books by being the first pair to complete this Herculean task.

The charity rowers wanted to monitor their energy expenditure during the challenge. So we at Iso-Analytical volunteered to help out by providing them with a doubly labelled water kit which they could use during the trip. The kit consisted of doubly labelled water drinks, collection containers for urine samples and everything needed to keep records of the sampling times:

On their return we will measure the two sets of urine samples that they will have collected from two study periods. Measuring the differential loss of deuterium from the body (only lost as water) and oxygen-18 (lost as water and carbon dioxide) allows us to calculate their total energy expenditure over study periods as long as two weeks. We're expecting Nick and Hamish's energy expenditures to be somewhat higher than normal!

To find out more about the challenge, track their progress and the charity they are supporting, please visit their website: Row for Heroes

Thursday, 25 March 2010

Iso-Analytical Student Award Provides a First for Deuterium Analysis

Unravelling complexities in benthic food webs using a dual stable isotope (hydrogen and carbon) approach.

Peter Deines, Matthew J. Wooller and Jonathan Grey, Freshwater Biology (2009) 54, 2243-2251.

In the journal article above the authors provide preliminary evidence to suggest that hydrogen and carbon isotope values in macroinvertebrates may be used to distinguish between methane formation pathways and help to explain inter-depth and inter-specific differences between co-existing chironomid species found in the same lake.

Peter Deines of the Max Planck Institute for Limnology, Plon, Germany used his Iso-Analytical Student award to send samples to our laboratory for analysis. Samples of chironomid larvae collected from German lakes were measured for their deuterium abundance. As far as the authors are aware this is the first study to use deuterium as a second biochemical marker in combination with carbon-13 (measured in their own laboratory), to unravel linkages between microbial fauna in sediment and macroinvertebrate consumers.

Friday, 19 March 2010


28th to 30th April 2010, University of Exeter

The annual meeting of the Stable Isotope Mass Spectrometer Users Group (SIMSUG) presents an ideal opportunity to share our experiences of analysing stable isotopes both formally and informally. Registration for the meeting and accomodation and submission of abstracts is now open. More details can be found on the SIMSUG website which can be accessed at the link below:


Iso-Analytical are one of the sponsors of the meeting and will be in attendance throughout. I look forward to meeting new and existing customers and catching up with colleagues and friends I have met in the 30+ years I have been involved in research with stable isotopes.

Steve Brookes

Tuesday, 9 February 2010

Inter-laboratory Testing - Honey

Food analysis using Isotopic Techniques - Proficiency Testing Scheme.

Results of carbon-13 and nitrogen-15 analysis of Honey undertaken in the first round of 2008 are shown below. The Z-scores (see explanation below the charts) show that the participating laboratories were in good agreement with each other and our own Z scores are comfortably in the desired range.

The evaluation of data is performed according to the ISO/IUPAC/AOAC International Harmonised Protocol for Proficiency Testing of analytical laboratories. Individual laboratories results are expressed as Z-scores:

Z = (x-X)/s

Where :
x is the reported result from the participating laboratory.
X is the assigned or "true" value for the analyte being determined. In this exercise the assigned values are taken as the robust mean of all reported results.
s is the target value for standard deviation. In this exercise the target SD values are derived from recently reported collaborative trial results or from the robust standard deviation of all reported values.

If X and s are good estimates of the population mean and standard deviation, and the underlying distributions are normal, Z is normally distributed with a mean of zero and unit standard deviation.