Spectrophotometer Usage
Spectrophotometer Usage - Related Videos
07:38
Introduction to the Spectrophotometer
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2023
The spectrophotometer is a routinely used instrument in scientific research. Spectrophotometry is the quantitative measurement of how much a chemical substance absorbs light by passing a beam of light through the sample using a spectrophotometer. In this video, basic concepts in spectrophotometry, including transmittance, absorbance and the Beer-Lambert Law are reviewed in addition to the components of the spectrophotometer. These concepts provide a foundation for how to determine the...
11:02
Methods to Discover Alternative Promoter Usage and Transcriptional Regulation of Murine Bcrp1
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Cited by 1 •
2016
With the murine ABC transporter Bcrp1 (Abcg2) as an example, in-silico protocols are presented to detect alternative promoter usage in genes expressed in mouse tissues, and to evaluate the functionality of the alternative promoters identified using reporter assays.
07:44
Quantification of dsDNA using the Hitachi F-7000 Fluorescence Spectrophotometer and PicoGreen Dye
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Cited by 6 •
2010
Demonstration of quantification of dsDNA using Molecular Probes PicoGreen dye and Hitachi F-7000 Fluorescence Spectrophotometer equipped with a microplate reader accessory.
10:29
Microvolume Protein Concentration Determination using the NanoDrop 2000c Spectrophotometer
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Cited by 129 •
2009
Microvolume samples are quantified by a spectrophotometer system that uses natural surface tension to retain samples without the use of cuvettes or capillaries. The dynamic range of protein concentrations and speed by which they can be measured are greatly increased with this method.
06:15
Concentration Determination of Nucleic Acids and Proteins Using the Micro-volume Bio-spec Nano Spectrophotometer
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Cited by 19 •
2011
This communication presents data on the accuracy and reproducibility of the BioSpec-nano UV-VIS spectrophotometer for dsDNA and protein quantitation. Even with ultra-small volumes (1 to 2 L), reproducibility is excellent, while the automated wiping function improves throughput and results in minimal carryover for more precise results.
FAQs
Wavelength determines which light response contributes to the measurement, so it should match the biological question and selected analytical target. Changing the wavelength can change the observed absorbance or transmission and therefore the apparent quantitative result. In practice, careful selection helps researchers obtain a more informative signal when estimating nucleic acids, proteins, cell density, or reaction changes.
The reference blank establishes the comparison intensity against which the sample is evaluated. This step helps separate the sample’s measured light response from the background associated with the measurement conditions. Without an appropriate blank, absorbance values may be shifted, weakening concentration estimates or comparisons among biological samples. Blank measurements therefore support calibration and reproducibility.
Bubbles and turbidity interfere with the light path rather than representing the intended dissolved sample response. Bubbles can disrupt how light travels through the cuvette, while turbidity can alter the detected intensity because the sample is not optically clear. These effects may produce unreliable absorbance or transmission values, so careful sample preparation is essential before recording biological measurements.
A reliable workflow begins with appropriate sample preparation, followed by instrument calibration and measurement of a reference blank. The sample is then placed in a cuvette, examined at the selected wavelength, and recorded for quantitative analysis. Keeping these steps consistent, while avoiding bubbles or turbidity, improves comparability across samples and supports reproducible biological experiments.
Spectrophotometer usage supports several common biological measurements, including estimates of nucleic acid and protein concentration, cell-density assessment, and enzyme-activity monitoring. The same general measurement principle can therefore serve both composition-focused assays and processes that change over time. Selecting the relevant wavelength and preparing each sample carefully helps align the recorded signal with the intended biological outcome.
Repeated measurements make it possible to follow enzyme activity or a biochemical reaction over time rather than relying on a single endpoint. Researchers can compare the changing light response at successive observations to assess reaction progress or activity patterns. Consistent wavelength choice, blanking, calibration, and sample handling are important because procedural variation can be mistaken for biological change.