Methods and apparatus for measuring the light absorbance of a substance in a solution
View Patent ↗Disclosed is an apparatus for measuring the absorbance of a substance in a solution, comprising: i) a sample cell ( 30 ) of known path length (b) for containing said solution (S), said cell being transparent to light of a predefined wavelength spectrum; ii) plural LED's each being independently operable by means of a controller ( 25 ) each for emitting light, within said predefined wavelength spectrum, along a light path; iii) a band pass filter ( 22 ) in the light path; iv) a beam splitter ( 24 ) for dividing light from said source propagating along the path into a first portion and a second portion, said first portion being directable by the beam splitter toward a reference detector ( 42 ) and said second portion being directable into the cell ( 30 ); v) a reference detector ( 42 ) for detecting the intensity of said first portion of light directed by said beam splitter; and vi) a sample detector ( 40 ) for detecting the intensity of the second portion propagating from the cell; the apparatus allowing a sample in the cell to be inexpensively subjected to more than one wavelength of light for quicker or more accurate analysis.
1. A method for measuring the absorbance of a substance, the method comprising:
directing a first light beam outputted from a first light-emitting diode (LED) on the substance, the first light beam having a first wavelength;
quantifying the intensity of the first light beam as it exits the substance;
determining, from the quantified intensity of the first light beam, a first absorbance value of the substance;
determining when a change in the first absorbance value reaches a threshold;
directing, in response to the change reaching the threshold, a second light beam outputted from a second LED on the substance, the second light beam having a second wavelength different than the first wavelength;
quantifying the intensity of the second light beam as it exits the substance; and
determining, from the quantified intensity of the second light beam, a second absorbance value of the substance.
2. The method of claim 1 , wherein the first light beam is directed through a first band pass filter corresponding to the first wavelength and wherein the second light beam is directed through a second band pass filter corresponding to the second wavelength.
3. The method of claim 1 , wherein determining the first absorbance value includes (i) directing a first portion of the first light beam to a reference detector, yielding a reference value and (ii) directing a second portion of the first light beam on the substance, yielding a measured value, and (iii) computing the first absorbance based on the measured value and the reference value.
4. The method of claim 1 wherein the first and/or second LEDs are UV LEDs.
5. The method of claim 1 , wherein the substance is in a solution, and the solution is selected from the group consisting of cell extract, cell lysate, cell culture, and mixtures thereof.
6. The method of claim 1 , wherein the substance is selected from the group consisting of a protein, a peptide, and a nucleic acid.
7. An apparatus for measuring the absorbance of a substance, the apparatus comprising:
a first light emitting diode (LED) configured to emit a first light beam having a first wavelength;
a second LED configured to emit a second light beam having a second wavelength;
a sample holder configured to hold the substance; and
a controller programmed to:
(i) direct the first light beam on the substance;
(ii) quantify the intensity of the first light beam as it exits the substance;
(iii) determine, from the quantified intensity of the first light beam, a first absorbance value of the substance;
(iv) determine when a change in the first absorbance value reaches a threshold;
(v) direct, in response to the change reaching the threshold, a second light beam outputted from a second LED on the substance, the second light beam having a second wavelength different than the first wavelength;
(vi) quantify the intensity of the second light beam as it exits the substance; and
(vii) determine, from the quantified intensity of the second light beam, a second absorbance value of the substance.
8. The apparatus of claim 7 , wherein the apparatus further includes a beam splitter, a reference detector, and a sample detector.
9. The apparatus of claim 7 , wherein one of the first LED and the second LED is a UV LED.
10. The apparatus of claim 7 , further including a moveable support supporting the first LED and the second LED.
11. The apparatus of claim 10 , wherein the support comprises a rotatable carousel supporting each of the first LED and the second LED.
12. The apparatus of claim 10 , wherein the support is configured to move linearly.
13. The apparatus of claim 7 , further comprising a moveable reflective surface.
14. The apparatus of claim 7 , further comprising an optical fiber associated with the first LED and an optical fiber associated with the second LED.
15. The apparatus of claim 7 , further comprising a first filter and a second filter associated with the first LED and the second LED, respectively.