Quantitative measurements of small amounts of samples as low as 0.5 to 1μL can be made by using the DeNovix DS-11 Spectrophotometer. When making a measurement, the target sample creates a liquid bridge between the lower and upper sampling surfaces.
The precision of the results is directly proportional to the precision of the calibrated distance present between the two sampling surfaces. This article shows how the DeNovix DS-11 SmartPath® Technology can be effectively used to maintain the measurement distance or pathlength within specification ultimately leading to reproducible and precise results.
Pathlength and Sample Concentration
The DS-11 software measures the concentrations of samples using the Beer-Lambert equation, which associates the absorbance to sample concentration and also the pathlength at which the light traverses the sample. This equation is written as A=ε*b*c.
A indicates the absorbance value, b is the sample’s pathlength expressed in cm, ε stands for absorptivity coefficient with units of L /mol*cm and c refers to the concentration of the sample in solution and expressed in terms of mol/L.
Shorter pathlengths are needed for samples of higher concentration. Using real-time absorbance data, the DS-11 microvolume mode determines the optimal pathlength for each sample (Figure 1). The DS-11 software positions the upper arm automatically ensuring that optimal pathlength was used to make the measurement. Pathlengths spanning from 0.5 to 0.02 mm are used by the DS-11 microvolume mode.
Figure 1. DS-11 microvolume mode. Image credit: DeNovix
Exquisite Pathlength Control
A combination of proprietary algorithms and opto-mechanical components in the DS-11 enable accurate pathlength control. The DS-11 keeps the pathlength within 1µm by means of a 80 thread/inch precision optical adjustment screw, a high-resolution encoder and a high motor gear ratio. This results in hyper-accurate motor movement and pathlength control during measurements.
No Recalibration Required
The DeNovix DS-11 small volume spectrophotometer uses a ‘home’ position, which is a factory-calibrated setting. The motor reaches the ‘home’ position again as soon as the system is switched on. The next step is estimating the number of motor rotations required to reach the 500µm start position. Given that the rotation to pathlength relationship is fully defined, shorter path lengths can be easily obtained.
Using proprietary software algorithms, the DS-11 spectrophotometer tracks the precision of pathlength and carries out the required modifications. Integrated with SmartPath® Technology, the DeNovix DS-11 instrument allows accurate pathlength control and delivers unparalleled performance.
About DeNovix, Inc.
DeNovix Inc. is an instrumentation company that designs, manufactures and sells laboratory equipment to meet the demands of today’s evolving life science technologies. Our focus is on providing innovative products and outstanding customer support. DeNovix is equipped with the financial, commercial and technical resources to deliver breakthrough products for your research success.
DeNovix offers the DS-11 Series Spectrophotometer/Fluorometer which combines fluorescence analysis and 1uL UV-Vis in the same instrument. Coupled with our new suite of dsDNA Fluorescence assays, DeNovix instruments provide a wider quantification range than any other instrument.
DeNovix instruments are found in life science research labs world-wide. Each instrument is a stand-alone system controlled by a built-in Android™ operating system (no PC). Labs love the smart-phone-like operation, impressive performance and the flexible connectivity of the instrument. Learn more about DeNovix Instruments and how they can benefit your lab.
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