Matrix effects, industrial

Instrumental Methods. Engineers in the IC industry prefer to use X-ray or FTIR spectroscopy to determine the quantities of phosphorus in thin films because of the speed of these methods. These spectroscopic methods are satisfactory for a relative indication of the dopant level in thin films or additives to metallization layers, but they do have serious drawbacks. X-ray spectroscopy is seriously affected by matrix effects and can easily be off by 15-20% of the actual concentration of dopant in thin films if the equipment is not properly calibrated against a material that has been analyzed by wet techniques. X-ray spectroscopy is further affected by the film thickness and the dopant profile throughout the film. 

A fundamental requirement for LC-MS/MS calibration materials is that matrix effects exerted by these materials are most similar to the matrix effects exerted by actual patients sample materials. Lyophilisation, virus inactivation and other procedures applied during the industrial production of calibration and control materials, may notably impact the ionization behaviour of extracts from such samples and can result in differential matrix effects in calibrators and actual patients samples. If the internal standard peak areas found for calibration samples systematically differ from those found in patients samples, inappropriateness of the calibration materials should be suspected. However, we have previously observed that calibration materials from different commercial sources lead to inaccurate tacrolimus results in an instrument specific manner, without showing deviations in the internal standard peak area. This effect was most likely related to ionization enhancement affecting the target analyte but not the homologue internal standard (ascomycin) ionization and being restricted to calibrator samples. This resulted in systematically low tacrolimus results of clinical samples in one instrument for one specific calibrator lot [52],... 

Hou W, Watters JW, McLeod HL (2004) Simple and rapid docetaxel assay in human plasma by protein precipitation and high-performance liquid chromatography-tandem mass spectrometry. Journal of Chromatography B 804 263-267 Schuhmacher J, Zimmer D, Tesche F, Pickard V (2003) Matrix effects during analysis of plasma samples by electrospray and atmospheric pressure chemical ionization mass spectrometry practical approaches to their elimination. Rapid Communications in Mass Spectrometry 17 1950-1957 Shah PW (2001) Guidance for Industry Bioanalytical Method Validation U.S. Department of Health and Human Services, Food and Drug Administration... 

Headspace Extraction Headspace (HS) extraction is a well-known method of sample preparation and is frequently used in many laboratories, especially in industrial applications. It involves a partitioning equilibrium between the gas phase and a sample (liquid or solid). In this technique, an aliquot of gas phase is sampled into GC. There are two types of analysis, static and d3Uiamic. In the static version, when the equilibrium is reached, the gas phase is injected into GC. In dynamic analysis, the volatiles are exhaustively extracted by the stream of gas. However, matrix effects result in decreased sensitivity for certain substances, especially polar and hydrophilic samples. A comprehensive book describing HS techniques was presented by Kolb [31]. 

Neutron Activation. In environmental and industrial process studies, neutron activation analysis (NAA) currently is being used widely because of its inherently high sensitivity and accuracy. In complex substances such as are found in solvent-refined coal and oil shale retorting processes, NAA is the method of choice for many trace element analyses because of its relative freedom from matrix effects. 

The sample does not come into physical contact with the membrane, thus minimising potential matrix effects and increasing the range of possible applications. Complex matrices such as Kraft liquor [272], industrial effluents with high concentrations of surfactants, organic compounds, emulsions and/or suspended particulate matter [273] and fermentation media [274] can be analysed using this approach. 

Depending on the X-ray source and the spectral modification devices, the LD are in the pg range for 2—3 kW X-ray tubes and in the fg range with excitation by means of synchrotron radiation. Figure 11.15 shows a typical TXRF spectrum the absolute detection limit values of typical TXRF instruments are shown in Fig. 11.10. Thus, TXRF permits to simultaneously determine trace elements in samples of small volume. Additional advantages are insensitivity to matrix effects, easy cahbration, fast analysis times and low cost. In practice, the method is in particular apphed for multi-element determinations in water samples of various nature and for the routine analysis of Si-wafer surfaces employed in the microelectronics industry. 

Standard additions of BTEXs to industrial wastewaters showed no matrix effect. The angular coefficient of the straight line obtained by four additions in the 0.1-2 ppm range was practically identical to that of a similar calibration plot using triply-distilled water (18,954 vs 18,883), the two lines being parallel (Figure 16.3). 

Mei 2004 Jessome 2006). Ion suppression (or occasionally enhancement) is a form of matrix effect that negatively affects LC-MS, regardless of the type of the mass spectrometer analyzer (Section 6.4), with respect to LOD, LLOQ, precision, accuracy etc. The importance of this phenomenon in the vahdation of analytical methods is emphasized by the extensive discussion in the Guidance for Industry on Bioanalytical Method Validation (FDA 2001). Figure 5.31 illustrates some of the possible causes of ionization suppression these include competition between analyte and other matrix components for either the total available charge or the available surface area of the droplet, as discussed above with respect to the dynamic range. 

The chemiluminescence-redox detector (CRD) is based on specific redox reactions coupled with chemiluminescence measurement. An attractive feature of this detector is that it responds to compounds such as ammonia, hydrogen sulfide, carbon disulfide, and sulfur dioxide. Hydrogen peroxide, hydrogen, carbon monoxide, sulfides, and thiols that are not sensitively detected by flame ionization detection can be detected with the CRD detector. Compounds that typically constitute a large portion of the matrix of many industrial samples are not detected, thus simplifying matrix effects and sample cleanup procedures for some applications. 

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