DEVIL: Duke Environmental Stable Isotope Laboratory

• If solid samples are not pre-weighed, add $10 per sample for weighing and encapsulation.
• Small gas samples requiring microvolume techniques will add $5 per sample.
• Freeze-drying of liquid samples to a solid can be done for $10 per sample.
• Extraction (cryogenic distillation) of plant/soil water $15 per sample.
• Commercial clients add $10 per sample for all samples.

Purified gases for dual inlet must be in 6mm or 9mm, 8" long breakseals, or in vacuum flasks, with no H₂O. Samples found to be impure must be discarded.

Acid-treated samples must be thoroughly rinsed in deionized water and dried at ~60 degrees C. For acid-fumed samples where rinsing is not desired, the sample must be double-encapsulated in silver capsules. The second wrapping should be applied immediately before shipping. Acid fuming can also be performed here for $10 per sample (plus $10 weighing per sample for unweighed samples).

All samples must be thoroughly homogenized, and milled or mortared to a fine grain size. Ammonia diffusion trap samples must be on paper filters using minimal acid.

ENRICHED ¹³C OR ¹⁵N MUST BE IDENTIFIED WITH ESTIMATED APPROX. ATOM %. ADD $10 PER SAMPLE. Since running enriched samples requires a reconfiguration, we must assemble large batches before running, which will increase turnaround times. Large enrichments are not necessary and should be avoided. We intend to analyze samples of no more than 1 or 2 atom% enrichment, preferably less. Remember that natural abundance of ¹³C is ~1.1 atom% and ¹⁵N is ~ 0.37 atom%. The natural abundance range is generally less than +/-40 per mil within most natural systems (this would be equal to +/-40 x 0.0011% = +/-0.044 atom % for ¹³C; +/-40 x 0.00037%= +/-0.0148 atom % for ¹⁵N). For a +1000 per mil enriched sample, this potential variability induces a maximum error of +/-4% of the measured enrichment, where +1000 per mil = 2.2 atom % for ¹³C, and +1000 per mil = 0.74 atom% for ¹⁵N). In most cases, error will be far less.

Prepay accounts are not affected by price increases until 3 months after the account starts.

* %C and %N must be at least roughly known to weigh correct sample sizes. We prefer to have at least 3 µmol of N and less than 200 µmol of C. All sample size requirements and qualities should be discussed with the technical director. See preparation guidelines page for instructions on preparing sample capsules. Leaking sample capsules must be returned. Charges may apply for correcting improperly prepared samples. Add $10 per sample for weighing and encapsulation if samples are not pre-weighed.

** Consult with lab director for preparation guidelines.

*** Consult with lab director regarding suitability of water samples. Samples should be provided in 12x32 mm septum vials with no air space. Add $5 per sample if supplied in other containers. In addition, there is a $5 extra charge if filtration is required. See preparation guidelines page for further instructions.

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Revised 3/17/2008 cwcook@duke.edu