Abstract
Iron (Fe) plays an important role within environmental systems. Synchrotron-based X-ray approaches, including X-ray absorption spectroscopy (XAS), provide powerful tools for in situ analyses of Fe speciation, but beam damage during analysis may alter Fe speciation during its measurement. XAS was used to examine whether experimental conditions affect the analysis of Fe speciation in plant tissues. Even when analyzed in a cryostat at 12 K, it was found that Fe III can rapidly (within 0.5–1 min) photoreduce to Fe II , although the magnitude of photoreduction varied depending upon the hydration of the sample, the coordination chemistry of the Fe, as well as other properties. For example, photoreduction of Fe III was considerably higher for aqueous standard compounds than for hydrated plant-root tissues. The use of freeze-dried samples in the cryostat (12 K) markedly reduced the magnitude of this Fe III photoreduction, and there was no evidence that the freeze-drying process itself resulted in experimental artefacts under the current experimental conditions, such as through the oxidation of Fe II , although some comparatively small differences were observed when comparing spectra of hydrated and freeze-dried Fe II compounds. The results of this study have demonstrated that Fe III photoreduction can occur during X-ray analysis, and provides suitable conditions to preserve Fe speciation to minimize the extent of beam damage when analyzing environmental samples. All studies utilizing XAS are encouraged to include a preliminary experiment to determine if beam damage is occurring, and, where appropriate, to take the necessary steps (such as freeze drying) to overcome these issues.
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Claims 6
Claim · model-written summary
Even in a cryostat at 12 K, Fe III can photoreduce to Fe II within 0.5-1 min during X-ray absorption analysis.
- Taxon
- rice
Oryza sativat0 - Outcome
- photoreduce to Fe IIe0
- Value
- within 0.5–1 mine0
- Setting
- cryostat at 12 Ke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tissues of rice plants”
e0“Even when analyzed in a cryostat at 12 K, it was found that Fe III can rapidly (within 0.5–1 min) photoreduce to Fe II”
Claim · model-written summary
Photoreduction of Fe III was considerably higher for aqueous standard compounds than for hydrated plant-root tissues.
Verbatim
e0“photoreduction of Fe III was considerably higher for aqueous standard compounds than for hydrated plant-root tissues”
Claim · model-written summary
Freeze-dried samples in the cryostat markedly reduced the magnitude of Fe III photoreduction.
- Taxon
- riceOryza sativat0
- Treatment
- freeze-dried samples in the cryostat (12 K)e0
- Outcome
- magnitude of this Fe III photoreductione0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tissues of rice plants”
e0“The use of freeze-dried samples in the cryostat (12 K) markedly reduced the magnitude of this Fe III photoreduction”
Claim · model-written summary
There was no evidence that the freeze-drying process itself caused experimental artefacts under the conditions used.
- Taxon
- riceOryza sativat0
- Treatment
- freeze-drying processe0
- Outcome
- experimental artefactse0
- Direction
- no evidencee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tissues of rice plants”
e0“there was no evidence that the freeze-drying process itself resulted in experimental artefacts”
Claim · model-written summary
Comparatively small differences were observed between spectra of hydrated and freeze-dried Fe II compounds.
- Outcome
- comparatively small differencese0
- Qualifier
- spectra of hydrated and freeze-dried Fe II compoundse0
Not reportedTaxon
Verbatim
e0“some comparatively small differences were observed when comparing spectra of hydrated and freeze-dried Fe II compounds”
Claim · model-written summary
The authors recommend that all XAS studies include a preliminary experiment to determine whether beam damage is occurring.
- Taxon
- riceOryza sativat0
- Outcome
- preliminary experiment to determine if beam damage is occurringe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tissues of rice plants”
e0“All studies utilizing XAS are encouraged to include a preliminary experiment to determine if beam damage is occurring”
The same questions in other papers
cold · nutrient: content · Oryza sativa (rice)Positive and negative results
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- negative
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See all 11 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.