my 'resilience' is due mostly to my own interest in this topic. I checked out Michael's paper and while it does discuss Ag it does not actually give any Ag values for the two algal reference materials they used (IAEA-392 and IAEA-393), only a range of values for replicates of natural Fucus samples. In fact, they don't report any trace metal values for the algal reference materials.
I did some research on these SRMs and apparently they were part of a series of three (the third being IAEA-391) that were certified in the mid-90s for "low", "environmental", and "elevated" trace metal levels. An early IAEA report refers to them as "Chlorella sp.". It looks like IAEA-392 is the only one still available, although curiously the reference sheet now refers to it as Scenedesmus obliquus. It could well have been reclassified however since algal taxonomy is a disaster, as you probably know, and names change almost daily even at the species level. This SRM is not certified for Ag.
The NIES CRM No. 9 (Sargassum fulvellum) is a great find, I was not familiar with that one. They also have a green microalga (CRM No. 3, Chlorella pyrenoidosa) but unfortunately again it is not certified for Ag. (I must say I was highly intrigued by their CRM No. 27 "Typical Japanese Diet" - I hope it is certified for Hg). Keep in mind however that Sargassum again is a brown seaweed, which is pretty far removed in habitat and tissue composition from Pseudokirchneriella. Apart from actual concentrations, it might still be better to go with something like spinach leaves or clover.
"[...] more than half the banana genome is shared with humans (a fact more
evident among some of my acquaintances than others)" - Sir Robert May
Dr. Johan Schijf
Assistant Professor, Aquatic Environmental Geochemistry
UMCES/Chesapeake Biological Laboratory
P.O. Box 38, 1 Williams Street
Solomons, MD 20688-0038
Tel. (410) 326-7387 (office) 7392 (lab)
Fax (410) 326-7341
e-mail: [log in to unmask] Manuel Ramiro Dias Pastorinho <[log in to unmask]>:
> Thank you all very much for your invaluable inputs.
> Steve: not a profiling exercise, but your family name would point
> more towards a "kalimera!" rather than to a "Bom Dia!"(where did you
> learn Portuguese?)
> Johan: thanks for pointing out alternatives, but more particularly
> for the resilience!
> Meanwhile I discovered that NIES (apparently still) produces
> a CRM (No.9) from a brown algae "Sargasso" (Sargassum fulvellum),
> that actually indicates certified values for Ag.
> A rare combination of virtues on these uncertifiable days. Thus
> granting it "personal holy grail" status.
> Ramiro Pastorinho, PhD
> Post-Doctoral Fellow
> CESAM - Center for Environmental and Marine Studies
> Ecotoxicology Laboratory
> Department of Biology
> University of Aveiro
> 3810-193 Aveiro
> Fax: +351 234 426 408
> mobile: +351 96 83 82 252
> Colorado School of Mines
> Department of Chemistry and Geochemistry
> Coolbaugh Hall
> 1500 Illinois Street
> Golden, CO 80401
> Voice: (+1) 303-273-3996
> Mobile: (+1) 720-785-4764
> Fax: (+1) 303-273-3629
> email: [log in to unmask]