CloudSpec™ Technology
CloudSpec™ offers a remarkable advantage over traditional UV/Vis instruments—transparent samples are no longer a necessity. Our patented technology measures spectra free from optical scatter while adhering to the Beer-Lambert law, allowing precise determination of analyte concentrations.
CloudSpec is easy to use, takes ≈15 seconds per measurement and has applications from brewing to biotech and beyond.
Scatter-Free Absorption (SFA)
CloudSpec measures true absorbance in scattering media. Because traditional UV/Vis (strictly an extinction measurement) is the sum of scatter and absorption the scatter can get in the way.
CloudSpec measures two spectra simultaneously and derives a third from those two:
· Regular UV-Vis (extinction) - measured directly
· Scatter-Free Absorption (absorption) - measured directly
· Optical scatter (scattering) - absorption subtracted from extinction
SFA Technology
CloudSpec eliminates scatter using two optical pathways and an integrating sphere, enabling independent measurements of both transmission UV/Vis (extinction) and scatter-free absorption.
In traditional UV/Vis, the transmitted signal loses light to both scattering and absorption. With SFA technology, light collected inside the sphere is only from scatter, ensuring the measured spectrum reflects only the sample's absorption.
CloudSpec’s Measurement Modes
CloudSpec produces three spectra simultaneously. The graphic below compares the spectra obtained by CloudSpec from the same RNA-loaded LNP samples for each measurement mode. Click on the upper tabs to compare the different measurement modes for the same samples.
Scatter-free absorption spectra. RNA A260 = 0.5 O.D.
Concentration of RNA = 12.5µg/ml
Spectrum includes scatter. LNP+RNA A260 = 1.2 O.D.
Apparent RNA concentration = 30µg/ml
Error = 140% overestimate
Scatter contribution isolated from the extinction spectrum.
Ca. 60% of the traditional UV/Vis spectrum comes from scatter for the loaded LNPs.
CloudSpec Solves Some Important Problems
Accuracy
SFA allows you to accurately measure the true absorption spectrum of a scattering sample in a simple single measurement. The absorption value is converted to a concentration measurement by multiplication with the extinction coefficient.
It is impossible to accurately measure absorption of scattering samples using transmission UV/Vis because the scatter must be approximated from other information, e.g., extrapolation of scattering spectra from non-absorbing regions, if available.
Because scattering scales with the 6th power of the particle size and the inverse 4th power of the wavelength the fit must be very precise. SFA does not have this limitation.
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Noise
Due to the way SFA works it is able to overcome limitations of noise in multiple ways.
Firstly, in a subtraction of a fitted scattering function, the relative noise is amplified (a large number minus a large number), which is not the case with SFA. Secondly, SFA's dual pathways enable a larger effective pathlength, which increases sensitivity and reduces noise, even at low concentrations.
These factors mean that as scatter increases even small concentrations of material can be accurately measured, even when scattering >> absorption.
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FAQs
In traditional UV/Vis measurements samples need to be brilliantly clear and free from scatter. CloudSpec eliminates the effects of turbidity, even in highly cloudy liquids.
While it might seem impossible, samples as cloudy as milk can be measured. As long as the sample can be pipetted, with a suitable solvent as a blank, you can obtain a scatter-free absorption spectrum.
Like traditional UV/Vis there is an upper limit to the absorbance that can be measured. Samples with absorbances above this limit must be diluted by a suitable amount. For a known sample, e.g., RNA, this will have a typical target value – in RNA, for example, this is ideally around 1-10µg/ml. For CloudSpec to work there is an additional consideration - the sample must be exactly 1ml in volume.
Regular UV-Vis is, strictly, an extinction spectrum, which is the combined loss of transmitted light by the sum of absorption and scatter. In the absence of scatter an extinction spectrum is equivalent to an absorption spectrum. However, when scatter is present, the extinction spectrum equals absorption + scatter and it is not always possible to separate the two effects exactly or well.