Elimination Of Matrix Effects Research Articles

Plasma parameters correction method based on plasma image-spectrum fusion for matrix effect elimination in LIBS.

Matrix effect is one of the obstacles that hinders the rapid development of laser-induced breakdown spectroscopy (LIBS), and it is currently a hot, challenging, and focal point in research. To eliminate the matrix effect, this study proposed a plasma parameters correction method based on plasma image-spectrum fusion (PPC-PISF). This method corrects the total number density, plasma temperature, and electron number density variations caused by matrix effect using effective features in plasma images and spectra. To verify the feasibility of this method, experiments were conducted on pressed and metal samples, and the results were compared with those corrected by image-assisted LIBS (IA-LIBS). For the pressed samples, after correction by PPC-PISF, the R2 of the calibration curves all improved to above 0.993, the average root-mean-square error (RMSE) decreased by 41.05%, and the average relative error (ARE) decreased by 59.35% evenly in comparison to IA-LIBS. For the metal samples, after correction by PPC-PISF, the R2 of the calibration curves all increased to above 0.997. Additionally, the RMSE decreased by 29.63% evenly, the average ARE decreased by 38.74% compared to IA-LIBS. The experimental results indicate that this method is an effective method for eliminating the matrix effect, promoting the further development of LIBS in industrial detection.

Study of the Stability and Homogeneity of Powdered Egg Matrix as a Candidate for Certified Reference Material for the Determination of Centesimal Composition

The full process of fresh egg preservation presents limitations and is associated with high transportation costs, while processed powdered eggs offer numerous advantages, such as high stability against degradation, providing extended shelf life, easy production, transportation, and favorable storage conditions. Traditional methods for determining the proximate composition of eggs and derivatives lack the capability to eliminate the matrix effect and do not guarantee adequate precision of the results. Therefore, Certified Reference Material (CRM) are the most suitable and effective tool to achieve this purpose. However, in Brazil, CRMs for powdered egg matrix are currently unavailable, although it is not possible to eliminate matrix effects, these can be included in the measurement uncertainty of each CRM. This study aimed to develop a candidate CRM for the powdered egg matrix with the requirements for the competence of testing and calibration laboratories (17034:2016) for proximate composition analyses. The analysis of variance (ANOVA) results for stability and homogeneity indicated no significant variation among the data obtained in the tests and the storage time of the material. Consequently, it was concluded that the powdered egg matrix is stable under simulated transportation conditions (short-term stability) as well as storage conditions (long-term stability) and exhibits adequate homogeneity for a CRM candidate.

Elimination of matrix effects in urine for determination of ethyl glucuronide by liquid chromatography–tandem mass spectrometry

RationaleAlcohol use disorder affects 4% to 5% of the world's population. Analysis methods are available for various biological fluids to detect this disorder. Determination of ethyl glucuronide in urine by the liquid chromatography–tandem mass spectrometry (LC/MS/MS) method is frequently used in forensic toxicology. These analyses are known to cause matrix effects.MethodsThe presented study describes the elimination of matrix effects for ethyl glucuronide. This study used two different LC/MS/MS systems containing orthogonal and z‐spray ion sources. Ethyl glucuronide was analyzed in negative polarity in electrospray ionization. A different dilution method was chosen for each study. The methods were developed and validated according to the European Medicines Agency bioanalytical method validation parameters.ResultsThe lower limit of quantitation of the developed methods was 0.025 μg/mL for ethyl glucuronide. The calibration curve of ethyl glucuronide was between 0.025 and 100 μg/mL with a correlation coefficient of >0.99 for the two methods.ConclusionsIt was determined that the analyses using the z‐spray ion source were more affected by the matrix effect. The two validated methods involve rapid analysis time and simple sample preparation. Also, the methods were applied to real patients' urine.

Point-of-Care Diagnosis on Selenium Nutrition Based on Time-Resolved Fluorometric Glycoaffinity Chromatography.

Given the lack of timely evaluation of the well-received selenium fortification, a neat lateral-flow chromatographic solution was constructed here by using the recently identified urinary selenosugar (Sel) as a strongly indicative marker. As there are no ready-made receptors for this synthetic standard, phenylboronic acid (PBA) esterification and Dolichos biflorus agglutinin (DBA) affinity joined up to pinch and pin down the analyte into a sandwich-type glycol complex. Pilot lectin screening on homemade glycan microarrays verified such a new pairing between dual recognizers as PBA-Sel-DBA with a firm monosaccharide-binding constant. To quell the sample autofluorescence, europium nanoparticles with efficient long-life afterglow were employed as conjugating probes under 1 μs excitation. After systematic process optimizations, the prepared Sel-dipstick achieved swift and sensitive fluorometry over the physiological level of the target from 0.1 to 10 μM with a detection limit down to 0.06 μM. Further efforts were made to eliminate matrix effects from both temperature and pH via an approximate formula. Upon completion, the test strips managed to quantify the presence of Sel in not just imitated but real human urine, with comparable results to those in the references. As far as we know, this would be the first in-house prototype for user-friendly and facile diagnosis of Se nutrition with fair accuracy as well as selectivity. Future endeavors will be invested to model a more traceable Se-supplementary plan based on the rhythmic feedback of Sel excretion.

Development and validation of a multiple headspace solid-phase microextraction method for accurate and precise analysis of the aroma of Tawny and White Port wines.

An accurate and precise Multiple Headspace Solid-Phase Microextraction (MHS-SPME) method was developed and validated for quantifying the volatile composition of White and Tawny Port wines. SPME extraction conditions were optimised using a four-factor three-level Box-Behnken design with three blocks and two replications. Optimal extraction conditions were similar for both Port wines. The method showed good linearity (0.001-50mg/L), precision (<5%), and detection limits (<1μg/L), well below the olfactory detection threshold. Recoveries higher than 95% were obtained. Twenty-three aroma compounds were quantified in Tawny and, for the first time, in White Port wines, including five acids, fourteen esters, the most abundant class, and four norisoprenoids, whose levels apparently increased with age. White Port wines had a lower abundance of aroma compounds. Results show that this MHS-SPME method is suitable for analysing volatile composition of White and Tawny Port wines, with reduced costs, manipulation time and eliminating matrix effects.

Assessment of total sample consumption infrared-heated system for minimization of matrix effects in ICP-tandem mass spectrometry

A total sample consumption infrared-heated system (IR-TSC) has been coupled to ICP-tandem mass spectrometry (ICP-MS/MS) for the first time. The objective of this study was to assess the analytical performance of the IR-TSC system, in terms of analytical figures of merit and mitigation of matrix effects. Twenty-seven elements have been determined: Ag, Al, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, K, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, Tl, V and Zn. Different operating conditions, including nebulization flow rate and spray chamber temperature, were optimized to improve sensitivity, signal stability, and plasma thermal conditions. The results showed that the infrared-heated sample introduction system improved the signal intensity by a factor of 2 to 4 compared to a conventional sample introduction system, whereas the limits of detection (LODs) improved by a factor going from 1.2 (Ba) to 3.3 (Cr) for a sample containing 2% HNO3. Meanwhile, for a 10% ethanol sample the improvement factor ranged from 1.4 (Ti) to 3.8 (Cr). Matrix effects for solutions containing inorganic acids or high content of sodium (2% HNO3, 10% HNO3, 20% HNO3, 10% HCl; 500 mg kg−1 Na, 500 mg kg−1 Na + 10% HNO3) were mitigated under optimum conditions (IR-TSC at 125 °C). Meanwhile, for solutions containing organic solvents (10% ethanol, 10% acetic acid, and 10% formic acid) it was not possible to eliminate matrix effects, even when applying an internal standard. For Se and As, elements spectrally interfered, the combination of IR-TSC sample introduction system with oxygen as reaction/collision gas mode in ICP-MS/MS provided accurate results. For 10% HNO3 and 10% HCl relative intensities values, calculated taking the signal intensity obtained for 2% HNO3 as reference, were close to the unity. Environmental and clinical control and certified reference materials were analyzed by means of an external calibration approach, with most of the elements showing concentrations not significantly different from the certified values. Finally, the IR-TSC was tested on twelve real samples, including seawater, surface water, peritoneal fluid, seminal plasma, wine, and bioethanol samples, demonstrating the system potential in different application fields.

Innovated single flush on-line solid-phase extraction in bead injection format for flow programming-based determination of creatinine in human urine

Reaction-based assays are commonly automated and miniaturized via flow analysis. However, aggressive reagents can affect or destroy even the chemically resistant manifold during long-term use. Using on-line solid-phase extraction (SPE) can eliminate this drawback and allow for high reproducibility and further advanced automation, as presented in this work. Determination of creatinine in human urine, an important clinical marker, by sequential injection analysis was achieved using bead injection on-line SPE with specific UV spectrophotometric detection, providing the necessary sensitivity and selectivity of the method for bioanalysis. The automated SPE column packing and disposal, calibration, and fast measurement highlighted the improvements in our approach. Variable sample volumes and a single working standard solution eliminated matrix effects, broadened the calibration range, and accelerated the quantification.Our method comprised an injection of 20 μL of 100 × times diluted urine with aqueous acetic acid solution pH 2.4, sorption of creatinine in a strong cation exchanger SPE column, washing out urine matrix with 50% aqueous acetonitrile, and elution of creatinine with 1% ammonium hydroxide. The SPE step was accelerated by a single flush of the column when the eluent/matrix wash/sample/standard zones sequence was created in the pump holding coil, and then the sequence of the zones was flushed into the column at once. The whole process was continually spectrophotometrically detected at 235 nm, subtracted from the signal at 270 nm. A single run duration was less than 3.5 min. Method relative standard deviation was <5.0% (n = 6). A calibration range was linear within the range of 0.02–0.30 μg creatinine (R > 0.999), covering 1.0–15.0 mmol/L creatinine in urine. The standard addition method used two different volumes of a single working standard solution for quantification. Results proved the effectiveness of our improvements in the flow manifold, bead injection, and automated quantification. The accuracy of our method was comparable to the routine enzymatic assay of real urine samples in a clinical laboratory.

Development of polyanion-metal ion solution systems to overcome phospholipids-related matrix effects in LC-MS/MS-based bioanalysis

Phospholipids-related matrix effects are a major source impacting the reproducibility of analyte quantification in LC-MS/MS-based bioanalysis. This study intended to evaluate different combinations of polyanion-metal ion based solution system for phospholipids removal and elimination of matrix effects in human plasma. Blank plasma samples or plasma samples spiked with model analytes were proceeded with different combinations of polyanions (dextran sulfate sodium (DSS) and alkalized colloidal silica (Ludox)) and metal ions (MnCl2, LaCl3, and ZrOCl2) followed with acetonitrile-based protein precipitation. The representative classes of phospholipids and model analytes (acid, neutral, and base) were detected using multiple reaction monitoring mode. The polyanion-metal ion systems were explored for providing balanced analyte recovery and phospholipids removal by optimizing reagent concentrations or adding formic acid and citric acid as the shielding modifiers. The optimized polyanion-metal ion systems were further evaluated for eliminating matrix effects of non-polar and polar compounds. Any combinations of polyanions (DSS and Ludox) and metal ions (LaCl3 and ZrOCl2) could completely remove phospholipids at best-case scenario, while the analyte recovery is low for compounds with special chelation groups. Addition of formic acid or citric acid can improve analyte recovery but significantly decrease the removal efficiency of phospholipids. Optimized ZrOCl2-Ludox/DSS systems provided efficient phospholipids removal (>85%) and adequate analyte recovery, and the systems also correctly eliminated ion suppression or enhancement of the non-polar and polar drugs. The developed ZrOCl2-Ludox/DSS systems are cost-effective and versatile for balanced phospholipids removal and analyte recovery and provide adequate elimination of matrix effects.

Lateral Flow Test System to Control Total Content of Muscle Tissues in Raw Meat Products.

Assessment of the composition of meat-containing products is the task in demand due to their frequent deviations from declared recipes. The paper presents the developed test system for immunochromatographic determination of total meat content. The assay is based on the simultaneous use of monoclonal antibodies, which specifically interacts with mammalian skeletal troponin I, and polyclonal antibodies, which specifically detect bird immunoglobulin Y. To integrate the detection of both types of meat by the same test strip, the antibodies are mixed in the analytical zone of the test strip and in complex with a gold nanoparticle label. The chosen ratios of the antibodies for both mixtures provide the same contribution of different types of mammalian and bird raw materials of muscle tissues to the label binding. The test system demonstrates suitability for products containing beef, pork, rabbit, lamb, chicken, and turkey meat. The minimal detectable content of meat in samples is 0.1%. The samples for the testing are diluted 100 times, thus eliminating matrix effects, and providing high reproducibility of the color intensity for extracts of different compositions. The obtained results allow the recommendation of the developed test system for rapid on-site control of meat products.

Combination of quadrupole isotope dilution mass spectrometry with simultaneous derivatization and spray assisted droplet formation-liquid phase microextraction for the determination of methamphetamine in human urine and serum samples by gas chromatography mass spectrometry

In this study, an analytical method with high accuracy and precision was developed for the determination of methamphetamine in human urine and serum samples by gas chromatography–mass spectrometry (GC–MS). A simultaneous derivatization and spray assisted droplet formation-liquid phase microextraction (SADF-LPME) method was proposed to derivatize and preconcentrate target analyte. Quadruple isotope dilution (ID4) was used to provide high accuracy and precision for methamphetamine determination in the samples. After the optimization studies for the derivatization and microextraction parameters, limit of detection (LOD) and limit of quantitation (LOQ) for the developed SADF-LPME method were found to be 48.0 and 159.9 μg/kg, respectively. Recovery studies were implemented to verify the applicability and accuracy of the developed method for human urine and serum samples. The SADF-LPME method gave low percent recovery results (30.5–61.0%) for the spiked urine and serum samples showing that it failed to minimize or eliminate matrix effects for the analyte. Hence, methamphetamine acetamide-d3 was synthesized and purified in our research laboratory to be used as methamphetamine isotopic analogue in the ID4 method. When the SADF-LPME method was combined with ID4, the percent recovery values for urine and serum samples were calculated as 99.7–100.0% and 99.4–100.2%, respectively. These results demonstrated the applicability and accuracy of the proposed method for urine and serum samples.

Novel magnetic porous biochar derived from degreasing cotton as a multifunctional adsorbent for simultaneous efficient capturing and monitoring of multiple antibiotic residues

The construction of a novel multifunctional adsorbent for simultaneous sensitive detection and capture of multiple antibiotic residues in the environment and food samples remains challenging. In this paper, the novel magnetic porous biochar (MPBC) derived from low-cost degreasing cotton was well-constructed and prepared via a simple solvent-free and one-step carbonization which has a large surface area, 3D porous structure, and good magnetism. The acquired MPBC was first used as multifunctional adsorbents for synchronous sorptive removal, sensitive detection, molecular sieve selection, and magnetic separation, exhibiting excellent adsorption capacity (102.2 mg g−1) for multiple antibiotics (quinolones and sulfonamides) residue. Meanwhile, the MPBC could exclude the relatively large matrix compounds, thus eliminating matrix effects. What's more, this method has a higher detection sensitivity, a lower detection limit (0.043–0.067 μg L−1), and higher enrichment factors (111 <EFs<133) for trace multiple antibiotics detection by high-performance liquid chromatography (HPLC). Consequently, a fast, economical, effective, and sensitive method for analyzing of antibiotics in the environment and food samples was developed, and maybe it is an useful guide for routine detection in the food and environment inspection department. All of this indicates that MPBC is promising for simultaneous sensitive determination and efficient adsorption of multiple antibiotic residues in the environment and food samples.

Quantification in bioimaging by LA-ICPMS - Evaluation of isotope dilution and standard addition enabled by micro-droplets

This study explores quantitative bioimaging as enabled by laser ablation-inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS), designing standardization methods based on robotic micro-droplet dispensing. The potential of producing controlled and highly precise pL-volume droplets was exploited to establish on-tissue isotope dilution and standard addition. Both strategies eliminate matrix effects and offer high metrological order traceable to SI units. The absolute quantity was obtained for μm-sized regions of interest in tissue samples, as defined by the extension of the deposited pL-volume droplet. While the gold standard isotope dilution (ID) was restricted to the accurate quantification of a single element, i.d. platinum in different tissue samples (mouse liver, spleen and tumor tissue), multiplexed matrix-matched calibration was obtained by on-tissue standard addition by depositing a dilution series of certified multi-element standards. Here, the working range was determined by the heterogeneity of the tissue samples and the background levels of elements intrinsically present and/or artificially introduced during sample preparation. Both methods, ID and standard addition served as reference methods for validation of external calibration using gelatin-based micro-droplet standards. Given full ablation, these external standards revealed a high dynamic range together with an excellent repeatability. Where applicable, the cross-validation revealed consistent quantitative results for the three quantification approaches. The comparable sensitivity obtained for standard addition and external standardization, respectively expressed as slope of the calibration function, provided proof that gelatin-based micro-droplets could serve as matrix-matched calibrations. Therefore, gelatin micro-droplets offer a valid tool for multiplexed matrix-mimicking standardization at high-throughput.

A multi-model fusion algorithm as a real-time quality control tool for small shift detection

BackgroundPatient-based real-time quality control (PBRTQC), a complement to traditional QC, may eliminate matrix effect from QC materials, realize real-time monitoring as well as cut costs. However, the accuracy of PBRTQC has not been satisfactory as physicians expect till now. Our aim is to set up a artificial intelligence-based QC for small error detection in real laboratory settings. Taking tPSA as our unique research subject, data extraction, data stimulation, data partition, model construction and evaluation were designed. Methods84241 deidentified results for tPSA were extracted from Laboratory Information System of Aviation General Hospital. The data set was accumulated by way of data simulation. Independent training and test datasets were separated. After three classification models (RF, SVM and DNN) in ML constructed and weighted by information entropy, a multi-model fusion algorithm was generated. Performance of the fusion model was evaluated by comparing with optimal PBRTQC. ResultsFor 4 PBRTQC methods, MovSO showed overall better performance for 0.2 μg/L bias and optimal MNPed was equal to 200. For the fusion model, MNPeds were less than 12 for all biases, and ACC surpassed MovSO nearly 100 times. Except for 0.01 μg/L bias, ACC was more than 0.9 for the rest of biases. FPR was apparently lower than MovSO, only 0.2% and 0.1%. ConclusionThe fusion model shows outstanding performance and reduces incorrect and omitting error detection, adaptable for the real settings.

Click Isotope Mass Probe for Highly Selective Determination of Trace Steroid Hormones in Food Samples.

Matrix effects are a great challenge for the quantitative analysis of complex food samples by liquid chromatography-tandem mass spectrometry analysis (LC-MS/MS). Stable isotope labeling (SIL) has been widely used as an effective strategy to eliminate matrix effects. Herein, a copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click-reaction-based SIL method was proposed for a highly sensitive and selective determination of six synthetic steroid hormones in three different food samples (milk, yogurt, and eggs) by high-performance liquid chromatography (HPLC)-MS/MS. A pair of novel SIL agents, N-(2-azidyl ethyl) aniline (d0-AEA) and d5-N-(2-azidyl ethyl) aniline (d5-AEA) were synthesized to label steroid hormones in the samples and standard solution, respectively. The reaction accomplishes in 30 min at 60 °C. The heavy labeled standards were used as internal standards (ISs), which experience the identical ionization processes with light labeled samples to minimize matrix effects. After derivatization, the ionization efficiencies of steroid hormones were greatly improved by 2-54-folds, and the matrix effects ranged from 88.6 to 99.8%. The established method achieved satisfactory detection limits (0.1-2.5 μg L-1) and high recoveries (85-102%). These results demonstrated that the proposed method holds unique advantages for trace steroid hormones analysis in foodstuffs.

Ultrafast and high-throughput quantitative analysis of carbamazepine in human plasma by direct analysis in real time tandem mass spectrometry coupled with solid phase extraction to eliminate matrix effects

Therapeutic drug monitoring of carbamazepine is necessary for its clinical application with the purpose to reach therapeutic concentration and reduce the risk of concentration-dependent toxicity. An ultrafast analytical assay for quantification of carbamazepine in human plasma was developed and validated based on direct analysis in real time tandem mass spectrometry (DART-MS/MS). After reversed phase solid phase extraction with Waters Oasis HLB, carbamazepine and internal standard carbamazepine-D2N15 were monitored by positive ion mode followed by multiple reaction monitoring (MRM) of the transitions at m/z 237.1→194.0 and 240.1→196.2, respectively. The DART-MS/MS method is ultrafast and high-throughput and the analytical time for each sample is only 0.4 min. The assay was linear in the concentration range 0.50–30 μg/mL and intra- and inter-day accuracies were within ± 15% and trueness were < 13.9% at all concentrations. The method was successfully applied to therapeutic drug monitoring of carbamazepine in human plasma.

Alternative Strategies for the Calibration and Elimination of Matrix Effects in LC-MS/MS Multiresidue Analysis of Tea Matrix

Alternative Strategies for the Calibration and Elimination of Matrix Effects in LC-MS/MS Multiresidue Analysis of Tea Matrix

A novel fast-dried urine spot-based method for the analysis of EtS and EtG in urine by liquid chromatography tandem mass spectrometry

Ethyl sulfate (EtS) and ethyl glucuronide (EtG) in urine are biomarkers to monitor ethanol consumption. Due to their high polarity, severe matrix effects have been observed during analysis of EtS and EtG in urine by liquid chromatography tandem mass spectrometry (LC-MS/MS), which can lead to a loss of sensitivity and accuracy. In the present study, a novel and simple sample preparation approach based on fast-dried urine spot was established to reduce the matrix effect of EtS and EtG in urine. 20 μL of urine was dropped on the Whatman 903# paper and was subsequently dried by microwave in one minute. After ultrasonic assisted extraction with 500 μL of methanol, the analysis was conducted using an LC-MS/MS system. Limits of detection were 5 ng/mL and linear ranges were 10 ng/mL–10 μg/mL for both EtS and EtG. Matrix effects were in the range of 99.3–107.8% for EtS and 86.7–91.0% for EtG at three QC levels. Matrix effects for EtS and EtG were compared between the current method and other sample preparation methods including protein precipitation, and solid-phase extraction. The results showed that this fast-dried urine spot-based extraction method could eliminate matrix effects significantly in analysis of urine EtS and EtG by LC-MS/MS.

An accurate analytical method for the determination of cadmium: Ultraviolet based photochemical vapor generation-slotted quartz tube based atom trap-flame atomic absorption spectrophotometry

In this study, an eco-friendly and accurate analytical protocol was proposed for the determination of cadmium at trace levels. Prior to analysis in flame atomic absorption spectrophotometry (FAAS), an ultraviolet based photochemical vapor generation (PVG) method as a sample introduction system was employed to eliminate matrix effects. PVG system was combined with an online preconcentration technique called T-shaped slotted quartz tube-atom trapping (T-SQT-AT) for online preconcentration of cadmium in order to further increase analytical performance of the system. Hydrogen was used in the releasing of collected Cd atoms from the quartz surface. Under optimum conditions, limit of detection (LOD) and limit of quantitation (LOQ) of the developed method were specified as 2.5 ng/mL and 8.2 ng/mL, respectively. Percent recovery results for tap water and daphne tea samples were found to be between 87.6–105.3% and 90.9–103.3%, respectively.

Novel Approach for the Accurate Determination of Se Isotope Ratio by Multicollector ICP-MS.

In this work, a method for the accurate and precise determination of 82Se/78Se isotope ratio in natural samples of environmental and biological origin, using multicollector inductively coupled plasma mass spectrometry in a wet plasma mode without using neither hydride generation nor separation of Se, was developed. It was based on the optimized regression model with standard–sample bracketing (ORM–SSB) to efficiently correct instrumental isotopic fractionation/mass bias and matrix effects. In addition, three mass bias correction models of SSB alone, SSB combined with internal standard (IS–SSB), and ORM–SSB were compared for the Se isotope ratio measurements. NIST SRM 987 Sr was used as an internal standard, and the reproducibility of the results obtained with the proposed method was verified by measuring NIST SRM 3149 standard over different days (nine independent measurement sessions). Delta values of the 82Se/78Se isotope ratio were measured in selenium-enriched yeast-certified reference material SELM-1, natural selenomethionine samples, and model solutions of artificial seawater. Solutions obtained after thiol resin treatment were measured to demonstrate the applicability of the proposed method in eliminating matrix effects due to residual of thiol resin in the sample solutions. Among three mass bias correction models, ORM–SSB correction model proved to be the best to eliminate the matrix effects and instrumental drift. IS–SSB model offered also a good precision but was slightly less accurate. Both models showed good robustness against effects of different sample matrices. Finally, the SSB alone could not be recommended for Se isotope analysis as it produces inaccurate and imprecise results.

A solid-phase extraction method that eliminates matrix effects of complex pulp mill effluents for the analysis of lipophilic wood extractives

Abstract The extraction of lipophilic wood extractives from pulp and paper process waters proves to be a challenging task, due to harsh and alternating process and sample conditions. This study has determined the potential use of polymeric sorbents for solid-phase extraction (SPE) and compared to classical silica-based reversed-phase packed columns, with polymeric hydrophilic-lipophilic balanced (HLB) cartridges being the sorbent with the most potential. Recovery functions were obtained with an internal standard mixture representative for the main lipophilic wood extractive groups, which are fatty acids and alcohols, sterols, sterol esters and triglycerides. The impact of pH, sample volume and sample matrix, expressed as TOC and cations, on the retention behavior of lipophilic extractives during SPE of industrial samples were determined with polymeric HLB sorbent. High variations in the composition of pulp mill matrices led to different optimal extraction conditions. Thus, a new SPE protocol was developed, which bypasses matrix interferences and omits the loss of analytes due to sample preparation. The method is applicable to different pulp mill effluents with large discrepancies in pH and sample matrices, resulting in recoveries &gt;90 % with RSD &lt;5 % for all lipophilic wood extractives.