Matrix Effects In Quantitative Analysis Research Articles

Matrix Effects in Quantitative Analysis of Laser-Induced Breakdown Spectroscopy (LIBS) of Rock Powders Doped with Cr, Mn, Ni, Zn, and Co.

Obtaining quantitative chemical information using laser-induced breakdown spectroscopy is challenging due to the variability in the bulk composition of geological materials. Chemical matrix effects caused by this variability produce changes in the peak area that are not proportional to the changes in minor element concentration. Therefore the use of univariate calibrations to predict trace element concentrations in geological samples is plagued by a high degree of uncertainty. This work evaluated the accuracy of univariate minor element predictions as a function of the composition of the major element matrices of the samples and examined the factors that limit the prediction accuracy of univariate calibrations. Five different sample matrices were doped with 10-85 000 ppm Cr, Mn, Ni, Zn, and Co and then independently measured in 175 mixtures by X-ray fluorescence, inductively coupled plasma atomic emission spectrometry, and laser-induced breakdown spectroscopy, the latter at three different laser energies (1.9, 2.8, and 3.7 mJ). Univariate prediction models for minor element concentrations were created using varying combinations of dopants, matrices, normalization/no normalization, and energy density; the model accuracies were evaluated using root mean square prediction errors and leave-one-out cross-validation. The results showed the superiority of using normalization for predictions of minor elements when the predicted sample and those in the training set had matrices with similar SiO2 contents. Normalization also mitigates differences in spectra arising from laser/sample coupling effects and the use of different energy densities. Prediction of minor elements in matrices that are dissimilar to those in the training set can increase the uncertainty of prediction by an order of magnitude. Overall, the quality of a univariate calibration is primarily determined by the availability of a persistent, measurable peak with a favorable transition probability that has little to no interference from neighboring peaks in the spectra of both the unknown and those used to train it.

Elimination of matrix effects during analysis of perfluorinated acids in solid samples by liquid chromatography tandem mass spectrometry

Matrix effects can significantly hamper the accuracy and precision of the analysis results of perfluorinated acids (PFAs) in environmental solid samples. Several methods, such as standard addition, isotopically labeled internal standards, clean-up of SPE (solid phase extraction) eluents by dispersive graphitized carbon sorbent and substitution of eletrospray ionization (ESI) source by atmosphere pressure photoionization (APPI) source, were demonstrated for elimination of matrix effects in quantitative analysis of PFAs in solid samples. The results indicate that matrix effects can be effectively eliminated by standard addition, but instrumental analysis time will be multiplied. Isotopically labeled internal standards can effectively negate matrix effects of PFAs with the same perfluorocarbon chain length, but is not valid for the other analytes. Although APPI can eliminate matrix effects for all analytes, it is only suitable for analysis of high pollution levels samples. Clean-up of SPE eluents by dispersive graphitized carbon sorbent not only effectively negate the impact of matrix effect, but also avoid frequent clean of the ESI in order to maintain instrumental sensitivity. Therefore, the best method for elimination of matrix effects is the usage of dispersive graphitized carbon sorbent for clean-up of SPE elution.

More accurate matrix-matched quantification using standard superposition method for herbal medicines

Various analytical technologies have been developed for quantitative determination of marker compounds in herbal medicines (HMs). One important issue is matrix effects that must be addressed in method validation for different detections. Unlike biological fluids, blank matrix samples for calibration are usually unavailable for HMs. In this work, practical approaches for minimizing matrix effects in HMs analysis were proposed. The matrix effects in quantitative analysis of five saponins from Panax notoginseng were assessed using high-performance liquid chromatography (HPLC). Matrix components were found to interfere with the ionization of target analytes when mass spectrometry (MS) detection were employed. To compensate the matrix signal suppression/enhancement, two matrix-matched methods, standard addition method with the target-knockout extract and standard superposition method with a HM extract were developed and tested in this work. The results showed that the standard superposition method is simple and practical for overcoming matrix effects for quantitative analysis of HMs. Moreover, the interference components were observed to interfere with light scattering of target analytes when evaporative light scattering detection (ELSD) was utilized for quantitative analysis of HMs but was not indicated when Ultraviolet detection (UV) were employed. Thus, the issue of interference effects should be addressed and minimized for quantitative HPLC–ELSD and HPLC–MS methodologies for quality control of HMs.

Analytical Bias Between Species Caused By Matrix Effects in Quantitative Analysis of A Small-Molecule Pharmaceutical Candidate in Plasma

Suppression or enhancement of MS ionization, particularly evident when electrospray is used as the source of ions, has been widely discussed. An assay for a small-molecule pharmaceutical in dog plasma between 1-300 ng/ml was validated with a mean bias across the calibration range of 5.0%. When the calibration sample matrix was substituted for human plasma, the mean bias across the range increased to 29.1%. A study of bias originating as a result of matrix effects, arising from endogenous glycerophosphocholine species, in plasma sources is discussed. A simple strategy to assess the potential of any unmitigated matrix effect to bias quantitative analysis by nonequivalent ionization induction or suppression is evaluated.

Correction of Matrix Effect in Multielemental Quantitative Analysis by X-Ray Fluorescence Spectroscopy Using the Linear Behavior in the Analytical Range of the Substitution-Dilution Method

This paper is an analytical study of the possibility of applying the linear range of the substitution-dilution method to correct the matrix effect in quantitative analysis by X-ray fluorescence (XRF) spectroscopy. The analytical range is obtained from a series of samples prepared in the form of glass discs by substituting the unknown sample with a standard sample (substitution factor, h) including a diluent-melt. In general, the substitution-dilution method is hyperbolic in character and therefore the diluent is required to ensure linear behavior between If vs. h in the experimental range. The linear range is located between the concentrations of standard and unknown for each element analyzed. This linear model makes it possible to correct the matrix effect in quantitative analysis by XRF using a single multi-elemental standard for different types of samples with a complex matrix, such as geologicals and cements. The results found for Si, Ti, Al, Fe, Mn, Ca, K, and P in soil and sediment samples and Si, Fe, Al, Ca, and K in cements (white and gray) are statistically satisfactory. Thus, the mean relative standard deviation calculated for all analytes in each sample was: ±4.0% and ±5.0% in soils; ±5.0% in sediments; and ±6.0% or ±3.0% in cements, white and gray, respectively.

A mathematical model based on the limit dilution method to obtain linear calibration curves which eliminate the matrix effect in quantitative analysis by X-ray fluorescence

We propose a mathematical model from an analytical application viewpoint inspired in the limit dilution method. The theoretical development of the model and its results are given. The model shows that there is a linear relation between the inverse of fluorescence intensity and the inverse of the dilution factor; each analytic system (sample, diluent and analyte) is characterised by a general linear function which is easily obtained. The analytical applications arising from this linearity are of great importance in X-ray fluorescence analysis. The following immediate applications are proposed: direct procurement of the total correction factor Y/ H, rapid calculation of the fluorescence intensity of the analyte in a sample ( I i s) and direct calculation of the corrected fluorescence intensity ( I i sF). The suggested model makes it possible to deduce a linear function between the fluorescence intensity of the analyte and the analyte concentration in successive dilutions of a standard; this straight line behaves as a calibration curve with direct application in X-ray fluorescence analysis. The proposed model may be applied to complex samples of geological origin, with elimination of the matrix effect. The results obtained in the determination of Ca, K, Fe and Ti in a standard soil show complete agreement with the certified reference values with a relative error about 0.5%, even using a standard shale with very different chemical composition as reference sample.

オージェ電子分光法による不純物の定量分析 Ｓｉ中のＢ，Ｐ及びＡｓ，並びにＳｉＯ?S２?T中のＰ

Quantitative analysis of boron, phosphorus and arsenic in silicon and phosphorus in silicon dioxide has been made by Auger electron spectroscopy with the in situ ion milling technique. Ion-implanted species in polycrystalline silicon and silicon dioxide were used as standard samples. The experimental results indicate that the semi-empirical formalism for quantitative Auger analysis is valid for impurity concentration less than a few percent. Excellent linear relationship has been obtained between the implanted dose and the normalized Auger signal intensity within ±10% for boron and phosphorus and ±20% for arsenic. We also show matrix effects in quantitative analysis of phosphorus in silicon dioxide.