Photos by Daniel Boone, NAU
 
 

Sample submission - organics - δ34S via EA-CFIRMS

Since 2006, we have analyzed organic (e.g., animal and plant tissues) and inorganic (e.g., sulfate and sulfide minerals) samples for δ34S using our Costech EA (ECS4010) interfaced to our Thermo-Electron Delta Plus Advantage IRMS (via CONFLO III).

Samples are prepared in the same way as for CN isotope analysis. However, as there is typically much less S in organic materials, compared with C or N, sample weights much be adjusted accordingly in order to provide the correct amount of gas to the mass spec.

We typically run samples for δ34S and %S, in continuous-flow mode using a Thermo-Finnigan Deltaplus Advantage gas isotope-ratio mass spectrometer interfaced with a Costech Analytical ECS4010 elemental analyzer.  Helium flow rate is set at 120 ml/min. A 10-ml O2 loop supplies sufficient oxygen for flash combustion.  A standard CHNS 1-m GC column is set at 90°C for peak separation, in combination with one quartz tube filled with tungsten oxide and pure copper wire (set at 1020°C) and a second quartz tube filled with quartz turnings (set at 800°C).  Analysis of δ34S takes approximately 12 minutes per sample. The average daily run contains 80-100 samples (incl. standards). Data are normalized using 6 internationally-accepted isotope standards (IAEA S1, S2, S3, SO5, SO6, and NBS 127).  Our internal working standards are powdered bovine liver (NIST 1577b), mussel tissue (NIST 2976), oyster tissue (NIST 1566b), tomato leaves (NIST 1573a), and keratin (TCI chemical). Long-term precision on these standards is typically ± 0.30‰ for δ34S or better.  Sulfur isotope data are expressed relative to VCDT (see http://www.ciaaw.org/Sulfur.htm).

Please contact the lab manager to discuss the most appropriate weights for your samples, and to obtain our sample submission form for sulfur analysis.

Please note: At this time, we do not accept sediment/soil samples for δ34S, nor do we accept samples on glass filter filters.