Non-matrix Matched Calibration Research Articles

Nonaqueous Electroextraction with Tunable Selectivity for Direct, Fast, and Exhaustive Enrichment of Per- and Polyfluoroalkyl Acids from Oils and Food Contact Materials.

Widespread concerns have been raised due to the ever-increasing number of novel per- and polyfluoroalkyl acids (PFAAs) and the ever-decreasing level of legacy PFAAs. Most analytical methods for PFAAs suffer from a narrow range of analyzable PFAAs, insufficient sensitivity, poor performance for oil samples, and defective quantification without internal standards or blank matrices. To solve these challenges, a highly selective method for multiple PFAAs from oils and food contact materials (FCMs) was developed based on nonaqueous electroextraction (NE). Through theoretical derivation and experimental investigation, the selectivity of NE was discovered to be tunable, and the range of extractable analytes could be tuned by adjusting the dielectric constant of the sample solution. For PFAAs, the selectivity was attributed to the pKa-based differential migration mechanism, as PFAAs exhibited less variable pKa values in different solvents compared to interference components. The method achieved nonmatrix-matched calibration without internal standards and integration of sample cleanup, selective extraction, and exhaustive enrichment into a fast and convenient operation. The method provided low limits of detection (0.002-0.03 μg·kg-1), satisfactory accuracy (88.0-107.8%), and RSDs (<11.7%). Migration experiments from 33 FCMs to oils were further investigated. PFBS (<0.05-2.34 μg·kg-1) and PFBA (<0.2-0.398 μg·kg-1) were detected from most FCMs. This was the first attempt at PFAA analysis as well as oil sample analysis using an electric field-assisted extraction technique and also the first report on PFAA migration from FCMs into edible oils.

In situ element analysis of spodumenes by fs-LA-ICPMS with non-matrix-matched calibration: Signal beat and accuracy

In this work, in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis with non-matrix-matched calibration is proposed for determining the composition of spodumene samples. Accuracy of the quantification in dependence on instrument operating conditions and the signal beat effect on quantification accuracy have been investigated in detail. Using NIST SRM 610 as reference material for external calibration, the mass fractions of major, minor and trace elements (Li, Si, Al, Na, Mg, Mn, Fe, Ga, and others) were determined using femtosecond-LA-ICPMS and compared with nanosecond-LA-ICPMS. Helium (He) was employed as the carrier gas in the ablation cell, and the aerosols produced under hole drilling ablation condition are then transported to a quadrupole ICPMS by a mixture of He and Ar as the make-up gas. Results show that the carrier gas flow rate had a substantial effect on both transient signal structure and LA-ICPMS quantification. With different He flow rates, both synchronized and non-synchronized acquisition with and without aliasing in the transient signals recorded were compared. Synchronized acquisition settings could attenuate the oscillations in the transient signals substantially but showed large variability (up to 18% RSD for Li2O) among individual acquisitions. Non-synchronized acquisition, with and without visible aliasing, on the other hand, was producing reproducible results without systematic biases when averaging ion signals from a sufficient number of scans (>100) for quantification. For the latter it was found that non-aliasing methods allowed for a direct identification of heterogeneities or inclusions in the transient signals and these were thus preferred for analysis. The accuracy of the analyses with non-matrix matched calibration was evaluated by comparing the matrix Al2O3/SiO2 mass fraction ratios with those obtained by electron probe microanalysis (EPMA). It was found that operation with only 0.2 L/min of He achieved the best agreement, while higher gas flow rates caused an increase in Al2O3/SiO2 and Li2O/SiO2 mass fraction ratios. This is considered to be a result of differences in ionization efficiency within the ICP caused by the higher abundance of easily ionized elements in the spodumenes compared to the calibration standard. By selecting appropriate acquisition settings for sequential MS detection and robust operating conditions, the repeatability of the analyses could be improved to values less than 1% for the Li2O mass fractions determined. When using the proposed settings for the analysis of 11 spodumene samples of different origin, the Al2O3/SiO2 mass fraction ratios agreed within −2% to +4% to those obtained by EPMA. These results confirm that spodumenes can be accurately analyzed in situ by LA-ICPMS without matrix-matched calibration standards. While matrix elements of the studied spodumenes were all in a comparable range, minor and trace elements showed substantial intra- and inter-sample variabilities.

Micelle-dominated distribution strategy for non-matrix matched calibration without an internal standard: “Extract-and-shoot” approach for analyzing hydrophilic targets in blood and cell samples

The analysis of trace hydrophilic targets in complex aqueous-rich matrices is considerably challenging, generally requiring matrix-matched calibration, internal standard, or time-and-labor-intensive sample preparation. To address this analytical bottleneck, a non-matrix-matched calibration strategy without using internal standard was reported for the first time to analyze complicated biosamples such as whole blood, plasma, serum, and cell samples. This strategy, termed micelle-dominated distribution, also aimed at realizing the simple “extract-and-shoot” analytical process for such complex matrices. The micelle–matrix interaction was found to efficiently eliminate the matrix effect by dominating phase separation and analyte distribution between the extraction and matrix phases. Thus, calibration linear curves prepared in water were applicable to the analysis of all the above-mentioned sample types. Rapid distribution equilibrium within 4 min was achieved. This strategy could tolerate direct large volume injection, thereby providing two-order-of-magnitude enhancement in the sensitivity of ion-pair chromatography. The analytical method integrated cell rupture, matrix cleanup, analyte extraction, and on-column preconcentration into a fast and high-throughput operation. The successful application to the determination of exogenous pesticides and endogenous glutathione exhibited low limits of detection (0.0085–0.015 μg mL−1 for pesticides; 0.52 μg mL−1 for glutathione), wide linear ranges (0.028–50 μg mL−1 and 0.049–50 μg mL−1 for pesticides; 1.7–1000 μg mL−1 for glutathione), good linearies (R2 = 0.9994–0.9999), excellent accuracy (recoveries of 91.3–105.2%), and good precision (0.7–6.2% at the levels of 0.028 (or 0.049), 0.1, 0.5, and 50 μg mL−1 for pesticides; 0.5–8.7% at 1.7, 500, and 1000 μg mL−1 for glutathione).

Retracted Article: Non-matrix matched calibration of element contents in stainless steel by using nanosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry

Accurate determination of trace elements is urgently required because of the influence of trace elements (such as Fe, Si, Mn, P, Cr, Mo, and V) on the properties of stainless...

Retraction: Non-matrix matched calibration of element contents in stainless steel by using nanosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry

Retraction of ‘Non-matrix matched calibration of element contents in stainless steel by using nanosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry’ by Jiuling Meng et al., J. Anal. At. Spectrom., 2019, DOI: 10.1039/c8ja00443a.

Accurate determination of sulfur isotopes (δ33S and δ34S) in sulfides and elemental sulfur by femtosecond laser ablation MC-ICP-MS with non-matrix matched calibration

In this study, the laser- and ICP-induced S isotopic fractionation in different S-rich minerals was investigated by using femtosecond (fs) and nanosecond (ns) laser ablation MC-ICP-MS.

10th European workshop on laser ablation

Since the development of lasers 50 years ago, laser ablation, as a sampling technique for direct emission spectroscopy (LIBS) or in combination with inductively coupled plasma atomic emission spectrometry (LA–ICP–AES) or inductively coupled plasma mass spectrometry (LA–ICP–MS), has become a very attractive and efficient sampling technique for direct analysis of solids. The combination with ICP–MS, first introduced by Gray in 1985, has, especially, attracted much attention in the past 25 years and much progress has been reported. The direct and high-spatial-resolution analysis of major, minor, and trace elements and isotope-ratio determinations make the technique widespread and applicable to a wide variety of fields of research. The driving force of LA–ICP–MS has been geochemistry, which remains one of the major fields of application of this technique. However, the technique is gaining more attention in material science, biology, medical and forensic sciences, and archaeology. This is mostly because a large number of uncertainties during the ablation, transport, and excitation of laser-generated aerosols have been studied and have been substantially reduced, so that quantitative results with very good precision and accuracy can be achieved. This is mainly because of technological progress in laser technology. Today, almost all wavelengths used in LA– ICP–MS are in the low UV region, which enable representative sampling of a large number of materials. The short wavelength of 193 nm introduced in 1995 is well established and very successful in representative sampling of all non-conducting samples. In addition, the use of femtosecond laser ablation, with very short pulses, improved the sampling of conducting samples and substantially increased the field of applications . Most interesting, a number of applications have been reported in which non-matrix matched calibration strategies have been successfully applied. This feature, in particular, which is rather difficult to perform in other direct solid analysis techniques, makes the use of laser ablation very attractive. In conclusion, LA–ICP–MS for insitu analysis of solids can be placed in the same group of successful analytical techniques as ICP–AES or ICP–MS for liquid sample introduction. From the beginning of LA–ICP work, research was directed in two major directions: fundamental and applied studies. The fundamental research focused on the ablation process itself—the interaction of laser light and matter. Progress was made with regard to understanding the energy transfer, plasma generation, formation of particles (laser aerosol) from this plasma, and their transport phenomena. After the initial use of IR lasers low-UV became the spectral range of choice. A gradual reduction of wavelength from 1064 nm, via 266 nm and 213 nm, towards 193 nm improved the performance of LA units substantially. This is because of reduction of thermal effects at the site of ablation, making generation of the aerosol more tolerant of the actual sample composition. Applied studies contribute to a deeper understanding of geochemistry, material and biomedical sciences, and take advantage of the direct analysis of samples at micrometer spatial resolution. More Published in the special issue Laser Ablation, with Guest Editors Dieter Garbe-Schonberg, Jan Fietzke, and Detlef Gunther

Analyses of lithium-doped and pure magnesium diboride using ultraviolet nano- and femtosecond laser ablation inductively coupled plasma mass spectrometry

Lithium-doped and pure magnesium diboride crystals were quantified by nanosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In both cases, non-matrix matched calibration using a silicate glass (NIST SRM 610) was performed. The application of nanosecond LA-ICP-MS resulted in a boron and magnesium stoichiometry of MgB. In contrast, data obtained by femtosecond LA-ICP-MS indicate a boron and magnesium stoichiometry of MgB2, which was supported by supplementary measurements on the basis of X-ray diffraction using peak refinement. Concentration discrepancies of main constituents that suggest a wrong stoichiometry, as found for ns-LA-ICP-MS, have not yet been reported and can, therefore, be considered an example of extreme laser-induced elemental fractionation.

Quantitative analysis of Fe-based samples using ultraviolet nanosecond and femtosecond laser ablation-ICP-MS

The quantification capabilities of iron-based samples were investigated using three commercially available ultraviolet (UV) nanosecond (ns) and femtosecond (fs) laser ablation systems coupled to inductively coupled plasma mass spectrometry (LA-ICP-MS). A comparison of three pulsed laser ablation systems (ArF* excimer, Nd:YAG and Ti-sapphire) with different wavelengths and pulse time durations (15 ns, 4 ns and 150 fs, respectively) was performed. Minor and trace elements were determined using 57Fe as internal standard element. Using similar spatial resolution for all laser systems and commonly applied operating conditions for each system, higher ion-signals (25–30%) and more stable elemental ratios (10% TRSD) were obtained for UV-fs-LA-ICP-MS. Scanning electron microscope images and particle size distributions measured for UV-ns-LA systems showed a bimodal distribution formed by nano-sized agglomerates and micro-sized molten spherical particles. In contrast, due to reduced thermal effects achieved using ultra-short pulses, the particle size distribution measured using UV-fs-LA showed a broad monomodal distribution (nano-sized agglomerates in the range of 50–250 nm). Matrix-matched (within metallic samples) and non-matrix matched calibrations were applied for the analysis of Fe-based samples, using a silicate glass (SRM NIST 610) as non-matrix matched calibration sample (glass-metals). Improved analytical results in terms of precision and accuracy were obtained using femtosecond laser ablation when using similar matrices for calibration. Moreover, non-matrix matched calibration used for quantification provides more accurate results (5–15%) in comparison with both UV-ns-LA-ICP-MS (5–30% using Nd:YAG laser and 15–60% using ArF* laser).

Application of a particle separation device to reduce inductively coupled plasma-enhanced elemental fractionation in laser ablation-inductively coupled plasma-mass spectrometry

The particle size distribution of laser ablation aerosols are a function of the wavelength, the energy density and the pulse duration of the laser, as well as the sample matrix and the gas environment. Further the size of the particles affects the vaporization and ionization efficiency in the inductively coupled plasma (ICP). Some matrices produce large particles, which are not completely vaporized and ionized in the ICP. The previous work has shown that analytical results such as matrix-independent calibration, accuracy and precision can be significantly influenced by the particle sizes of the particles. To minimize the particle size related incomplete conversion of the sample to ions in the ICP a particle separation device was developed, which allows effective particle separation using centrifugal forces in a thin coiled tube. In this device, the particle cut-off size is varied by changing the number of turns in the coil, as well as by changing the gas flow and the tube diameter. The interaction of the laser with the different samples leads to varying particle size distributions. When carrying out quantitative analysis with non-matrix matched calibration reference materials, it was shown that different particle cut-off sizes were required depending on the ICP conditions and the instrument used for analysis. Various sample materials were investigated in this study to demonstrate the applicability of the device. For silicate matrices, the capability of the ICP to produce ions was significantly reduced for particles larger than 0.5 μm, and was dependent on the element monitored. To reduce memory effects caused by the separated particles, a washout procedure was developed, which additionally allowed the analysis of the trapped particles. These results clearly demonstrate the very important particle size dependent ICP-MS signal response and the potential of the described particle size based separator for the reduction of ICP induced elemental fractionation.

Adaptation and application of a multi-residue method for the determination of a range of pesticides, including phenoxy acid herbicides in vegetation, ased on high-resolution gel permeation chromatographic clean-up and gas chromatographic analysis with mass-selective detection

A multi-residue method to determine pesticides in vegetation samples is described. Blended samples were extracted with acetone and the pesticides partitioned into dichloromethane prior to being cleaned-up using high-resolution gel permeation chromatography. Investigations were made into the effects of altering the pH of the aqueous phase during partitioning. Rapid and efficient methylation of the phenoxy acids present was achieved using trimethylsilydiazomethane. The resultant solutions were then selectively and sensitively analysed by gas chromatography with mass-selective detection. The variation in results using matrix matched and non-matrix matched calibration standards was also explored. The method has been applied to grass samples spiked with pesticides from the following groups, phenoxy acid, organophosphorus, triazine, organochlorine, phenyl urea, chloroacetanilide and pyrethroid. Recoveries around 80–100% and reproducibilities of 2–4% ( n=4) were typically achieved at a spiking level ∼ 140 μg kg −1

In situ trace element determination of carbonates by laserProbe inductively coupled plasma mass spectrometry using nonmatrix matched standardization

Abstract The LaserProbe Inductively Coupled Plasma Mass Spectrometry (LP-ICP-MS) has shown great potential to precisely and quickly determine trace element compositions of minerals in situ at a scale of ≤ 60 μm. However, standardization is complicated, due to the lack of matrix-matched, homogeneous mineral standards. In this study, a nonmatrix matched calibration standard, the NIST 612 silicate glass, was employed to determine Sr, Y, Ba and REE concentrations in calcite and dolomite grain mounts. Using 43Ca as an internal standard, the results demonstrate that it is not essential to have a matrix-matched mineral standard by LP-ICP-MS. Routine limits of detection are ~10 ppb for REEs and ~200 ppb for Sr, Y and Ba, depending on laser operating conditions. Evaluation of precision and accuracy is made complex by heterogeneity of trace elements within single mineral grains. However, the best within-grain precision (determined from several LP sampling pits within an individual mineral grain) is considered to represent the maximum analytical error and is generally 10 grains) were analyzed. Nonmatrix matched standardization for quantitative analysis can successfully be used, because the small size laser probe ( ~ 10 μm) used in this study can generate much higher power density than the conventional size laser beam. At high power density, the sample ablation mainly results from plasma plume expansion induced by the laser, not from absorption of the laser beam and related thermal vaporization, as for conventional, low power density laser analysis. The plasma plume expansion as a major ablation process permits the ablation of even those materials usually transparent to laser (e.g., calcite). This technique can be applied to the analysis of trace elements of carbonates in thin sections, grain mounts and rock or mineral chips, thus avoiding extensive sample preparation with significant implications for studies of near-surface and environmental processes.