Table 1 shows some of the key differences between the two techniques….Comparison of NMR and MS.

NMR allows users to obtain rich structural information from the vibrations of the molecules in their natural environment while they’re still intact. NMR spectrometers simplify and speed up the data acquisition and analysis process. Users can use the established libraries of NMR spectrometers to identify molecules.

The greatest disadvantage of NMR spectroscopy and imaging compared with other modalities is the intrinsic insensitivity of the methods. The signal that can be generated in the NMR experiment is small and, for practical purposes, most strongly coupled with the concentration of the nuclei in the sample.

The two most commonly used methods are mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. Numerous methods within these two major techniques provide both complementary and supplementary information on the identity and concentration of metabolites.

Disadvantages of mass spec are that it isn’t very good at identifying hydrocarbons that produce similar ions and it’s unable to tell optical and geometrical isomers apart. The disadvantages are compensated for by combining MS with other techniques, such as gas chromatography (GC-MS).

There are four stages in a mass spectrometer which we need to consider, these are – ionisation, acceleration, deflection, and detection.

Basic Principle A mass spectrometer generates multiple ions from the sample under investigation, it then separates them according to their specific mass-to-charge ratio (m/z), and then records the relative abundance of each ion type.

The answer is no, your sample is destroyed during the analysis. What happens? Molecules in your sample become ionized, enter the mass spectrometer, and eventually collide with the mass analyzer electrodes.

Molecules in a sample are vaporized (converted to the gas phase by heating). Because mass spectrometry measures the mass of charged particles, only ions will be detected, and neutral molecules will not be seen.

Sample preparation for mass spectrometry is used for the optimization of a sample for analysis in a mass spectrometer (MS)….Sample phase.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is one of the most surface-sensitive chemical characterization techniques available and is considered a destructive technique since it must remove the topmost surface atoms and molecules before subsequent ionization and detection.

This includes different types of destructive testing methods such as tension tests, bend tests, Charpy impact tests, Pellini drop weight testing, peel tests, crush testing, pressure and fracture testing.

Destructive methods are based on the destruction of the state of equilibrium of the residual stresses in the cross section. From: Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges, 2014.

XRF (X-ray fluorescence) is a non-destructive analytical technique used to determine the elemental composition of materials. XRF analyzers determine the chemistry of a sample by measuring the fluorescent (or secondary) X-ray emitted from a sample when it is excited by a primary X-ray source.

The XRF sensor can only detect the possibility of PCB contamination. It detects chlorine, but it cannot differentiate between the two chlorine species. Therefore, if chlorine is found further tests must be conducted to determine if the chlorinated compounds are PCBs.

Elements lighter than Magnesium cannot be measured using XRF. This limitation of XRF makes it impossible to grade materials such as low carbon stainless steels, carbon steel, and low alloy materials because Carbon cannot be measured utilizing XRF analyzers.

Handheld XRF is not capable of directly measuring elements lighter than magnesium. This includes alloying elements such as lithium, beryllium, and carbon. These elements can be relevant in various applications, such as: Lithium in some aerospace aluminum alloys.

The device scans the metal material and identifies its key elements. However, it cannot detect carbon and some lighter elements and is not suitable for identification of pure carbon steel materials.

Light elements have energy levels that are low enough that they struggle to escape from the sample without being absorbed. So essentially, light elements are difficult to measure by portable XRF because their fluorescence struggles to reach the instrument for it to calculate how much of that element is present.

XRF (and particularly EDXRF) is ideally suited for very fast qualitative elemental analysis. Typically all elements from sodium through to uranium can be detected simultaneously, with good quality spectra obtained in seconds/minutes.

Usually the ED-XRF cannot detect oxygen, and the sample is often a mixture of metal oxides, in such a case, you can use “Oxides analysis”. If your sample is an Fe-Si alloy, you must use alloy analysis.

No similar experiments were done for fluorine because the detection limits for both methods, XRF and ICP-MS are to high. However, because of the chemical similarity of F, Cl and Br it can be assumed that an identical behaviour for F would be found.

As a rule of thumb the accuracy “out of the box” given by the difference between XRF value and assay can be as good as 0.2 to 0.5% for gold in jewelry, whereas the accuracy out of the box for minerals can be within 20% of the lab assay or even more if the sample is not homogeneous enough.

Sodium is the lightest element capable of being detected using energy dispersive XRF (Brouwer, 2003).

The first is the fact that the window is gone; that 4 (or 8) micron thick prolene window does a lot to attenuate light elements. Secondly, it ensures that the photons returning from the sample have a clear path as the helium can cover almost all the distance between it and the detector.

Is XRF a surface technique? XRF is an elemental analysis technique that can quantify many elements in a sample. The characteristic X-ray photons produced in the sample have specific energy (keV) and on the way to the detector get absorbed by other atoms in the sample.

Handheld XRF analyzers work by measuring the fluorescent (or secondary) X-rays emitted from a sample when excited by a primary X-ray source. Each of the elements present in a sample produces a set of characteristic fluorescent X-rays, or “unique fingerprints”.

This requirement can be met by using 15g of sample for most materials. Special care should be taken for the analysis of metal powders in high power (2-4Kw) WDXRF instruments.