Depending of the type of material being probed, the incident nir beam can undergo diffuse reflection mostly from the surface or penetrate through the sample, undergo multiple reflection and be detected at the same side as the incident beam. This will allow the nir source such as a halogen-tungsten lamp to be embedded within the body of the spectrometer rather than as a separate source.
The NirvaScan Spectrometer introduced by Allied Scientific Pro is an example of a nir spectrometer with a Tungsten Halogen lamp embedded with the body of the spectrometer. A typical handheld FTIR spectrometer can be of dimension 17cmx11cmx22cm excluding a handle whereas a nir-spectro-reflectometer such as the NirvaScan spectrometer introduced by Allied Scientific Pro can be as small as 6cmx5cmx3cm a factor of 45 smaller by volume.
An FTIR spectrometer must have a moving part a moving mirror whereas a nir spectrometer with an array detector could record all the dispersed wavelengths simultaneously without the use of any moving parts.
NirvaScan spectrometer does not have an array detector and utilizes a single element detector. A MEMS mirror will scan different wavelengths very quickly on the detector.
For most of the measurements in nir, if the sample such as a pill, seeds of coffee, wonder bread etc. For crop grains and seeds, the measurement can be done as is.
Figures 6 a and b show the source spectra. Most of the FT-NIR spectrometers are very bulky and a handheld version is hard to find on the market.
This may be due to the fact that a FT-NIR system operating at a shorter wavelength requires more displacement from the moving mirror to achieve a certain spectral resolution. The requirement of a moving mirror is also another disadvantage for the FT-NIR as compared to NIR, which can capture the whole spectra using an array detector with no moving parts. In conclusion, for heterogeneous samples and those which contain water which is mostly the case for samples in food industry, nir is the preferred choice.
Since it is more convenient to have a hand-held instrument which can be taken to a sample rather than a lab based instrument where samples are taken to it, nir is also advantageous to FT-NIR.
The interferometric method has the advantage of high throughput as compared to the dispersion technique whose throughput is limited by an entrance slit. These features are generally narrow, which gives a high resolution to FT-IR methods. The frequency you can do that at is very low, so that means that you don't have fantastic control of the process. Then, you have on-line, where you take a sample out through a little tube into an instrument that analyses so it does it automatically.
The problem there is that you don't know what's happening between measurements because you take a sample out. If there are rapid fluctuations in the process, you won't get that. In-line, you are looking at things happening live and that means that when you have dramatic changes, you can see them immediately.
Of course, it requires that you have a technology that you can put into the line. FTIR is difficult because it requires this very thin layer of milk, but it can be solved.
The advantage that you get out of it is that, in particular; your protein measurement becomes much more accurate compared to if you're using NIR, because NIR would probably be the method or the choice if FTIR is not possible.
Until now, FTIR has not been used in the process. That's because it's very difficult, because you need this very thin layer of milk, and how that is handled has been quite a challenge. You can actually do it - if you have some very fine motors you can control the cuvette so that it can move and it can move into position, so when the system is CIP'd, then you can have it open so that it's cleaned, and then you can close it again for measurements.
The other thing is that stability requires that you need to do some reference measurements from time to time. You need to do some mathematical tricks in order to not have that reference measurement once every hour or so, because you only have the opportunity every time you have a CIP. That might happen every 24 hours, for example. Right now, we're at the stage that we've just released the MilkoStream FT, which solves the problem of doing references all the time.
It can do references every time there's a CIP. It doesn't need any more than that. It can open during a CIP so that it can be cleaned, probably between batches, and then, it can close through some very sophisticated motor control, into a distance of 35 microns, where it's optimal to measure milk in a cuvette. Moving fully in-line makes a huge difference because you can control your process to a very large detail. If something is changing, you can see it immediately.
Also, the maintenance has been reduced quite significantly because we are just using the CIP system in-line in order to clean the instrument. There's no specific cleaning or no reference measurement or so on, everything is happening in relation to the CIP. Finally, there's no flow system. No moving parts to be replaced in the flow system as there is with the current equipment available.
The main advantage is that we can measure protein at a very high accuracy compared to competing methods. That's the reason why its FTIR in the line and not any other method. Dec, FTIR spectroscopy is, in principle, very similar to Near Infrared NIR spectroscopy, but works at longer wavelengths where the chemical information from the samples is more specific.
While the sensitivity and range offered by the longer wavelengths offers many advantages, it runs into a natural barrier when testing more solid samples.
The desire to monitor the physical form of some raw materials and take analysis from the lab to the sample has spurred the growing adoption of cartable NIR systems.
However, NIR's poorer selectivity and the impact of physical attributes such as particle size, packing density and moisture on results pose a significant practical challenge for cost-effective implementation of the technique. Emerging from recent advances in hardware miniaturization and embedded analysis is handheld Raman spectroscopy, a technique that combines many of the favorable attributes of FTIR and NIR. Newsletter Signup. I agree to the Terms.
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