1. 34 S Analysis of Solids by EA-IRMS

2. Sample Preparation Material needs to be dry and homogenous Organisms can be analyzed whole if small enough Sample weights: 20-30 µg sulfur < 20 µg sulfur by arrangement Most organic samples are 0.1-1% sulfur dry weight

3. Encapsulating Samples Weigh samples into tin capsules Add oxidant: 2mg of V 2 O 5 or No 2 O 5 to each capsule

4. 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

5. 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

6. IRMS Methodology 32/34 obtained from measurement of SO 2 ion beams, 64/66. Modification of Baublys et al. 2004. Baublys, K., Golding S., Young, E., & B. Kamber. 2004. Rapid Commun. Mass Spectrom.

7. The SO 2 problem: Oxygen Isotopes Oxygen isotopes will produce bias in measured 64/66 ratios Solution(s): measure or minimize variation in oxygen isotopes 64 SO 2 32 S 16 O 16 O 66 SO 2 34 S 16 O 16 O 33 S 17 O 16 O 32 S 17 O 17 O 32 S 16 O 18 O Relevant isotopomers of SO 2

8. Oxygen Homogenization Oxidant and molecular oxygen used in flash combustion supply reservoir of donor oxygen during SO 2 formation Hot quartz chips further homogenize oxygen signal

9. Chromatography

10. 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.