Chemical Tracers LabOratory

Head: Aaron Fisk, Associate Professor and Canada Research Chair
            afisk@uwindsor.ca, 519-253-3000 ext. 4740

Manager: Ms. Ellis, MSc
            sandrae@uwindsor.ca, 519-253-3000 ext. 4851

STABLE ISOTOPE SERVICES
 
Our laboratory can provide analysis of carbon and nitrogen isotopes for a variety of sample types.  In the past analysis has occurred on animal tissues (including invertebrates), plant tissues, zooplankton, phytoplankton and soil. We have analyzed samples and collaborated with researchers at the University of Georgia, the Ontario Ministry of Natural Resources, Environment Canada, the Norwegian Institute of Nature Research, Icelandic Institute of Natural History, the University of Glasgow, and many others.  

The instrumentation in our laboratory consists of an Elemental Analyzer (Costech) - Isotope Ratio Mass Spectrometer (Thermo Delta V) (EA-IRMS) for δ13C, δ15N, %N and %C analysis.  This system is a dual-inlet system.  The pneumatic auto sampler for the elemental analyzer allows us to process up to 150 solid samples at a time. 

Our Elemental Analyzer, Costech instruments, ESC 4010

 
Our Isotope Ratio Mass Spectrometer, Thermo Delta V Advantage

Internal Standards and Calibration (Quality Control)

Our laboratory currently runs multiple (up to 6) standards with each sample run.  These standards include those made ‘in-house’, as well as commercially purchased standards.  Our standards have verified values for δ13C and δ15N through inter-laboratory comparisons. These standards include acetanilide, bovine, poplar leaf, and glycine standards.  We run standards every 12 samples to ensure consistency over each run.  We obtain strong linear regressions due to the accuracy of standards we run.  As well, each 12th sample is repeated 3 times (at no cost) to ensure consistency, of both homogenated samples and our IRMS.  We also run sucrose and ammonium sulfate, certified by the National Institute of Standards and Technology, approximately every two weeks to ensure reliability of results.

Preparation of Solid Samples for Stable Isotope Analysis

1. Sample preparation will depend on the type of sample that you wish to analyze.  We have in-house capabilities for all sample preparation techniques described below.Solid samples must be dried.  Sample can be oven dried, only if the samples contain forms of N that won’t be lost through oven drying.  Preferably, samples can be freeze dried.  The laboratory contains a ThermoSavant ModulyoD freeze dryer with 16 port-manifold. 

Our Freeze drying system, the ThermoSavant ModulyoD

2. Dried samples must be ground to a powder.  Samples can be ground using a ball mill or manually using a mortar and pestle, depending on the sample type. This helps to ensure sample homogeneity. The laboratory contains a Spex SamplePrep 8000 Ball Mill/Mixer.

Our Spex 8000 ball mill used for grinding samples.

3. Samples may be lipid extracted.  This is an optional step that can be taken when look for δ13C and δ15N in tissues such as liver and muscle, or in other samples such as eggs.  In the laboratory we add 2:1 Chloroform: Methanol to each sample. We then vortex and leave for a minimum of 24 hours.  After 24 hours, we pour the contents of the vial through a filter into a previously weighed tin tray and rinse the tissues 2 more times with Chloroform: Methanol. After 24 hours, we reweigh the tin tray to get the amount of lipid present in the tissue.  For accurate lipid extraction, a minimum of 0.5 grams of tissue is required.  Lipid extractions may be performed with less tissue, but results may not be reliable. Alternatively, soxhlet extraction may be used. 

4. Samples are weighed and encapsulated.  Sample weight will depend on sample type.  For most tissue samples between 400-600 µg are required.  For plankton and soils samples between 3000-4000 µg are required.  The sample is weighed into a special tin or silver capsule.  Please note that each sample must be carefully prepared once weighed out into the capsule, and must be rolled and shaped into a ball.  This helps ensure that samples do not get caught in the autosampler.  In particular if samples are flat, the autosampler will not be able to operate and samples will be lost or ruined. Also note that large samples also pose a problem and may not combust! Once samples have been weighed, we organize them into 96 well tissue culture plates. 

If you choose to send samples that have not been processed please consider the following.

• Send more sample than we require.  We are only human, and there is that possibility that errors may occur while processing your samples. Therefore it is to your benefit to send more sample than is needed for analysis.  As well, this allows for the possibility of external issues (such as shipping) or problems with instrumentation that we did not account for.
  
  
• Keep labels simple and sample organized.  If possible, keep sample names short and sweet!  Samples labels are re-recorded throughout processing and analysis, by using short, simple and unique names for each sample, it helps ensure that sample names are recorded properly, and that if an error does occur it can be traced quickly.  Additionally, including or emailing spreadsheets of all samples which are sent helps us to keep the laboratory organized.  When possible, organizing your samples in boxes or plastic bags also helps us to process samples more quickly. 

Please see PRICE LIST for more information on services or contact the laboratory manager at sandrae@uwindsor.ca

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