You need to have a deep ocean nearby so the ocean sulfate is not mixed with coastal / riverine sulfur.

Dr. Max Coleman
NASA Jet Propulsion Laboratory, Caltech
Voice (818) 393-6353
;  Cell (818) 687-7704

On 13 Oct 2020, at 04:50, Michalski, Greg M <[log in to unmask]> wrote:

NBS 127 is essentially seawater sulfate precipitated with Ba...If you have an ocean nearby

From: Stable Isotope Geochemistry <[log in to unmask]> on behalf of Leon Clarke <[log in to unmask]>
Sent: Tuesday, October 13, 2020 4:46 AM
To: [log in to unmask] <[log in to unmask]>
Subject: [ISOGEOCHEM] NBS 127 (BaSO4) and delta34S(VCDT) normalisations


I was in the process of purchasing NBS 127 (BaSO4, delta34SVCDT = +21.12 per mil), to use within a 3-point barium sulfate calibration including IAEA-SO-5 (+0.49 per mil) and IAEA-SO-6 (-34.05 per mil).

However, I have recently been informed that NIST have “pulled [NBS 127] from stock to undergo stability test due to it nearing the expiration date”. Consequently, I would appreciate it if anyone can comment on the following questions:

1.       Has anyone identified another enriched BaSO4, that is homogeneous w.r.t. todelta34SVCDT?


2.       Do the other enriched international standards (IAEA-S-4, elemental S, +16.90 per mil, and IAEA-S-2, Ag2S, +22.62 per mil) plot on a straight line with the three barium sulfate reference materials?


3.       Does anyone have any NBS 127 that they no longer have any use for? (I would be able to swap for another reference material.)

Many thanks in advance, Leon

Dr Leon J. Clarke
Senior Lecturer in Environmental Analytical Chemistry
Department of Natural Sciences
Faculty of Science and Engineering
Manchester Metropolitan University
John Dalton East
Chester Street
Manchester M1 5GD
United Kingdom


Tel: +44 (0)161 247 1412