But to have an accurate and reproducible reading you should choose a wavelength with maximum absorbance. In this case, you are using the scattered light, not the absorbed light as your signal. So you should avoid wavelengths where there are absorption peaks.... read more ›
The greater the density, the lower the percent transmittance. The wavelength selection is important and depends on the color of the suspension medium. However, it should not be changed during the experiment. It is customary to use 420 nm wavelength if the blank is nearly colorless, and 550 nm if it is yellowish.... continue reading ›
What is the best wavelength of light to use in order to measure the concentration of blue dye in solution?
More specifically, a wavelength around 880 nm seems the most appropriate choice.... continue reading ›
The absorbance of a DNA sample measured at 260 nm on a spectrophotometer or microplate reader can be used to calculate its concentration.... see more ›
Justify your answer. The optimum wavelength is 450 nm because that is the wavelength of maximum absorbance by FeSCN2+(aq) .... continue reading ›
What this also means is that the higher the molar absorptivity, the lower the concentration of species that still gives a measurable absorbance value. Therefore, the wavelength that has the highest molar absorptivity (λmax) is usually selected for the analysis because it will provide the lowest detection limits.... view details ›
a) The wavelength range that exhibits the greatest absorbance is 480 nm-540 nm, which corresponds to the colors blue green, green, and yellow green.... view details ›
The wavelength of maximum absorbance is used when determining the concentration of a colored solution since at this wavelength a slight change in concentration allows for a significant change in the absorbance of light.... continue reading ›
If we look at the sun radiation spectrum, it is obvious that 550 nm is near the wavelength which has the maximum power can get from the sun. So for making a standard wavelength to compare T and A with others, it seems that 550 nm is a good choice! 550 nm is in the green spectra.... view details ›
Glycogen concentration is measured by absorbance. Because the recommended wavelength by the assay kit manufacturer is 570. Based on wavelength/absorbance plot provided by the manufacturer, we determined that the out of the wavelength filters that we have, the 540 nm is most ideal.... view details ›
Methylene blue has a strong absorption band centered at 660 nanometers, in the red region of the visible spectrum, and transmits wavelengths below 600 nanometers, bestowing a blue color to the dye.... see more ›
The coloured filters are chosen to select the wavelength in which the dissolved solute will absorb the most. For most experiments the common wavelength range is between 400 and 700 nm, but when some analytes absorb in the ultraviolet range (less than 400 nm) then modification of the colorimeter is generally required.... see more ›
A wavelength longer than the peak absorbance and shorter than the peak absorbance will result in more light being recorded by the detector. You can determine peak absorbance by taking several readings of the same sample and varying the wavelength of the spectrophotometer.... view details ›
Concentration measures the amount of a substance dissolved in a volume of another substance. It can be measured in moles per liter, also called molarity.... see more ›
Wavelength of maximum absorption (Lamda Max) the extent to which a sample absorbs ligght depends upon the wavelength of light. the wavelength at which a subtance shows maximum absorbance is called absorption maximum or lamda max.... see more ›
The spectrophotometer is more sensitive to absorbance changes at this wavelength. Thus, the wavelength of maximum absorbance is typically used for the analysis. To determine the wavelength of maximum absorbance, the absorbance over the range of 400nm to 650nm is measured, usually in intervals of 25nm.... continue reading ›
- Transmission or transmittance (T) = I/I0 ...
- Absorbance (A) = log (I0/I) ...
- Absorbance (A) = C x L x Ɛ => Concentration (C) = A/(L x Ɛ)
By shining a light beam into a grating whose spacing d is known, and measuring the angle θ where the light is imaged, one can measure the wavelength λ.... see more ›
The Beer-Lambert law is a linear relationship between the absorbance and the concentration, molar absorption coefficient and optical coefficient of a solution: The molar absorption coefficient is a sample dependent property and is a measure of how strong an absorber the sample is at a particular wavelength of light.... read more ›
Why do we only record absorbance at a wavelength that gives the greatest absorbance value for Allura Red Λmax )?
Why do we only record absorbance at a wavelength that gives the greatest absorbance value for Allura Red AC (max wavelength)? Molecules all have a specific wavelength at which they absorb the most.... read more ›
Most of the protocol, the given formula to calculate the concentration of unknown substance is = Test OD/Std OD * Std Concentration.... read more ›
This is Beer'sLaw: at constant path length, the absorbance is directly proportional to the concentration of absorbing material. in which b is the path length, C is the concentration, and a is a constant which depends on the wavelength of the light, the absorbing material, and the medium (solvent and other components).... read more ›
Here's how it works
Allura Red has the greatest absorption of light which is 500 nm. Therefore, the best wavelength of light provided by this colorimeter is 470 nm (blue light).... see details ›
Why are you measuring the absorbance of the solution at 550nm? Since the spectrophotometer measures, the amount of light absorbed by a sample and the samples will be yellow or purple, due to CO2 indicator, then the best wavelength of light to shine on the samples is the green spectrum.... continue reading ›
Why is it important to set the wavelength of the spectrophotometer before measuring the absorbance of the solutions?
It is important to "blank" the spectrophotometer before taking an absorption measurement of a sample at each new wavelength, because the water and cuvette also absorb light, so the spectrophotometer won't measure the absorption of water and cuvette.... continue reading ›
The measurement of ultraviolet absorbance at 280 nm has proven especially useful, since the molar absorptivity (extinction coefficient) at 280 nm can be predicted directly from a protein sequence. This method, however, is only applicable to proteins that contain tryptophan or tyrosine residues.... view details ›
Proteins generally absorb UV light at 280 nm while peptide bonds absorb UV light at 214 nm. When quantifying proteins using the Lowry and Buiret methods, absorbance or optical density is measured at 540 nm.... see details ›
Protein concentration can be estimated by measuring the UV absorbance at 280 nm; proteins show a strong peak here due to absorbance from Tryptophan and Tyrosine residues (commonly referred to as A 280).... see details ›
Question: How should the concentration of a colorless sample be determined? Using a UV spectrophotometer AO Using a VIS spectrophotometer .... continue reading ›
Use the wavelength knob to set the desired wavelength. Extreme wavelengths, in the ultraviolet or infrared ranges, require special filters, light sources, and/or sample holders (cuvettes).... continue reading ›
Terms in this set (10)
%T is the amount of light that is trying to pass through and absorbance is what the light is trying to pass through.... continue reading ›
The Beer-Lambert law states that there is a linear relationship between the concentration and the absorbance of the solution, which enables the concentration of a solution to be calculated by measuring its absorbance.... read more ›