Beer's law in analytical chemistry

Liebhafsky, H. A.; Pfeiffer, H. G.

doi:10.1021/ed030p450

Cited by 23 publications

(17 citation statements)

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“…The characteristic absorption length is dened as the depth at which the incident intensity is reduced by a factor of 1/e. Using Beer's law, 94,95 the absorption length, L P , is 1/ a, where a is the absorption coefficient.…”

Section: Light Absorption and Charge Transportmentioning

confidence: 99%

Photocatalysts with internal electric fields

2014

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The photocatalytic activity of materials for water splitting is limited by the recombination of photogenerated electron-hole pairs as well as the back-reaction of intermediate species. This review concentrates on the use of electric fields within catalyst particles to mitigate the effects of recombination and back-reaction and to increase photochemical reactivity. Internal electric fields in photocatalysts can arise from ferroelectric phenomena, p-n junctions, polar surface terminations, and polymorph junctions. The manipulation of internal fields through the creation of charged interfaces in hierarchically structured materials is a promising strategy for the design of improved photocatalysts.

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Section: Light Absorption and Charge Transportmentioning

confidence: 99%

Photocatalysts with internal electric fields

2014

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“…In fact, derivation of Beer's law excludes the interaction between particles. 35 Here, sensitivity is defined in terms of the minimum measureable change in transmitted light intensity for a given change in component concentration DC min ¼ 1 jdI=dCj DI min , where I ¼ I o e Àax (Beer-Lambert law 36 ) and…”

Section: Sweat Chemical Analysis Using Hnq Dyementioning

confidence: 99%

A portable optical human sweat sensor

Alomari

Liu

Mueller

et al. 2014

Journal of Applied Physics

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We describe the use of HNQ (2-hydroxy-1,4-naphthoquinone or Lawsone) as a potential sweat sensor material to detect the hydration levels of human beings. We have conducted optical measurements using both artificial and human sweat to validate our approach. We have determined that the dominant compound that affects HNQ absorbance in artificial sweat is sodium. The presence of lactate decreases the reactivity of HNQ while urea promotes more interactions of sodium and potassium ions with HNQ. The interactions between the hydroxyl group of HNQ and the artificial sweat components (salts, lactic acid, and urea) were investigated comprehensively. We have also proposed and developed a portable diode laser absorption sensor system that converts the absorbance at a particular wavelength range (at 455 ± 5 nm, where HNQ has an absorbance peak) into light intensity measurements via a photocell. The absorbance intensity values obtained from our portable sensor system agrees within 10.4% with measurements from a laboratory based ultraviolet-visible spectrometer. Findings of this research will provide significant information for researchers who are focusing on real-time, in-situ hydration level detection.

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“…Using these, predicted c 1+ abundances of the 7+ to 13+ c 1+ spectra (segmented colored bars) fit the experimental values to ≤3%. This proportional additivity of component reference spectra that yields the spectrum of the corresponding mixture is the classic Beer's law behavior long established for spectroscopic methods (e.g., visible, UV, IR) [12] as well as for MS [13]).…”

Section: Resultsmentioning

confidence: 78%

“…In a similar fashion, the c 1+ peaks for the 13-17 cleavage sites can result from two component spectra, one accounting for most of the 15-17 peaks. Mathematical deconvolution [12] of the 7+ to 13+ c 1+ data of sites 2-17 gives three component spectra, bottom left Figure 1. Using these, predicted c 1+ abundances of the 7+ to 13+ c 1+ spectra (segmented colored bars) fit the experimental values to ≤3%.…”

Section: Resultsmentioning

confidence: 99%

Charge Site Mass Spectra: Conformation-Sensitive Components of the Electron Capture Dissociation Spectrum of a Protein

Skinner

Breuker

McLafferty

2013

J. Am. Soc. Mass Spectrom.

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A conventional electron capture dissociation (ECD) spectrum of a protein is uniquely characteristic of the first dimension of its linear structure. This sequence information is indicated by summing the primary cm+ and zm+• products of cleavage at each of its molecular ion's inter-residue bonds. For example, the ECD spectra of Ubiquitin (M + nH)n+ ions, n = 7-13, provide sequence characterization of 72 of its 75 cleavage sites from 1843 ions in seven c(1-7)+ and eight z(1-8)+• spectra and their respective complements. Now we find that each of these c/z spectra is itself composed of “charge site (CS)” spectra, the cm+ or zm+• products of electron capture at a specific protonated basic residue. This charge site has been H-bonded to multiple other residues, producing multiple precursor ion forms; ECD at these residues yields the multiple products of that CS spectrum. Closely similar CS spectra are often formed from a range of charge states of Ubiquitin and KIX ions; this indicates a common secondary conformation, but not the conventional α-helicity postulated previously. CS spectra should provide new capabilities for comparing regional conformations of gaseous protein ions and delineating ECD fragmentation pathways.

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Beer's law in analytical chemistry

Cited by 23 publications

References 0 publications

Photocatalysts with internal electric fields

Photocatalysts with internal electric fields

A portable optical human sweat sensor

Charge Site Mass Spectra: Conformation-Sensitive Components of the Electron Capture Dissociation Spectrum of a Protein

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