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34 S Analysis of Solids by EA -IRMS. Sample Preparation. Material needs to be dry and homogenous Organisms can be analyzed whole if small enough Sample weights: 20-30 µ g sulfur < 20 µ g sulfur by arrangement Most organic samples are 0.1-1% sulfur dry weight. Encapsulating Samples.
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Sample Preparation • Material needs to be dry and homogenous • Organisms can be analyzed wholeif small enough • Sample weights: • 20-30 µg sulfur • < 20 µg sulfur by arrangement • Most organic samples are 0.1-1% sulfur dry weight
Encapsulating Samples Weigh samples into tin capsules Add oxidant: 2mg of V2O5 or No2O5 to each capsule
Organizing Trays • Load samples across rows of 96-wells trays • Do not leave empty wells between samples • Label trays uniquely and clearly • Place samples for different analyses in different trays
Paperwork • Complete an Analysis Order Form for each analysis type • Complete a sample list for each Analysis Order From • Email forms to sif@ucdavis.edu • Include printed copies with samples
IRMS Methodology • 32/34 obtained from measurement of SO2 ion beams, 64/66. • Modification of Baublyset al. 2004. Baublys, K., Golding S., Young, E., & B. Kamber. 2004. Rapid Commun. Mass Spectrom.
The SO2 problem: Oxygen Isotopes Relevant isotopomers of SO2 • Oxygen isotopes will produce bias in measured 64/66 ratios • Solution(s): measure or minimize variation in oxygen isotopes
Oxygen Homogenization • Oxidant and molecular oxygen used in flash combustion supply reservoir of donor oxygen during SO2 formation • Hot quartz chips further homogenize oxygen signal
Sulfur Data Reduction and Corrections • Blank • Drift • Size • Scale expansion • Corrections follow those of Kaiser and Röckmann 2008 Kaiser, J. & T. Röckmann 2008. Rapid Commun. Mass Spectrom.