Interferences in mass spectrometry

Enhanced molecular ion implies reduced matrix interference. An SMB-El mass spectrum usually provides information comparable to field ionisation, but fragmentation can be promoted through increase of the electron energy. For many compounds the sensitivity of HSI can be up to 100 times that of El. Aromatics are ionised with a much greater efficiency than saturated compounds. Supersonic molecular beams are used in mass spectrometry in conjunction with GC-MS [44], LC-MS [45] and laser-induced multiphoton ionisation followed by time-of-flight analysis [46]. 

Using standard solutions for quantifying concentrations in an unknown sample may give rise to measurement errors due to the influence of food matrix remnants in the injection solution. Ion suppression or enhancement is a typical matrix effect seen in mass spectrometry. Matrix-matched standards are generally used in order to avoid such possible matrix interferences. Standard addition is a valid alternative for dealing with matrix effects. On the other hand, standard addition or matrix based calibration curves require more manipulation, which is time- and money-consuming, whereas a greater risk of manipulation errors ensues. 

Any proteomic study starts with the collection of proteins from biological samples such as cell culture media, cultured cells, serum, or any biological fluid, and a variety of animal tissues. The first step is to obtain a protein sample under conditions of least protein degradation. This involves use of various protease inhibitors that stop the protein degradation. The use of protease inhibitors depends on the type of sample and the analytical technique used in the subsequent analysis. The selection of protease inhibitors used is critical since many protease inhibitors and detergents used in the preparation of tissue homogenates can interfere with mass spectrometry (MS)... 

Eq. (72) also shows that the intensity ratio of the atom and ion lines of an element will change considerably with the electron pressure in the plasma. Elements with a low ionization energy such as Na will thus have a strong influence on the intensity ratios of the atom and ion lines of other elements. This is analytically very important as it is the cause of the so-called ionization interferences, found in classical dc arc emission spectrometry but also in atomic absorption and plasma optical emission as well as in mass spectrometry. 

In optical emission and in mass spectrometry, spectral interferences remain an important limitation to the analytical accuracy achievable. In atomic emission this applies particularly to the heavier elements as they have the more line rich atomic spectra. When these heavy metals are present as the matrix, as is often the case in metal analysis, the necessitity of matrix separations is obvious when trace analyses... 

Ultrafiltration (UF) is used primarily to separate analytes of interest from macromolecules, such as proteins, peptides, lipids, and sugars, which may interfere with analyses, particularly affecting ionization in mass spectrometry. In residue analysis, molecular weight cut-off devices or spin filters coupled to microcentrifuge tubes are the most commonly used formats. Alternative formats such as the... 

In most analytical techniques used in geochemistry there is little attempt to separate the element to be analysed from the rest of the rock or mineral sample. The only exception is in mass spectrometry. Thus there is the possibility of interference of spectral lines or peaks so that the value measured is spuriously high due to overlap from a subsidiary peak of another element present in the rock. The effect of these interferences must be calculated and removed. 

Accoe, E, Berglund, M., Geypens, B., Taylor, P. (2008) Methods to reduce interference effects in thermal conversion elemental analyzer/continuous flow isotope ratio mass spectrometry 5 180 measurements of nitrogen-containing compounds. Rapid Communications in Mass Spectrometry, 22(14), 2280-2286. 

---