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• In vivo SPME-based methods are developed to determine neonicotinoids in bananas. • The R s values depend on the sample matrix, sampling durations, and individuals. • Equilibrium calibration shows better stability, repeatability and sensitivity. • Equilibrium calibrated in vivo SPME is superior to the QuEChERS pretreatment. • It is a talented on-site strategy for detection of pesticides in undamaged samples. In vivo solid-phase microextraction (in vivo SPME) is an emerging fascinating sample pretreatment technique, but its quantitative correction method is different from the traditional correction methods, which has become a bottleneck limiting its development. At present, the sampling-rate calibration and equilibrium calibration are mainly used, however, their characteristics and applicability are not clear. In this study, the sampling-rate calibration and equilibrium calibration were evaluated in the case of the determination of neonicotinoids in bananas by in vivo SPME. The factors that affect the sampling rate (R s), such as the matrix states, sampling durations, and individual differences were studied, and they all had impacts on R s. Conversely, the equilibrium distribution coefficient (K fs) remained constant after extraction equilibrium and the individual differences were smaller. The highest accuracy and precision were achieved by equilibrium calibration, and the relative recoveries were in the range of 83.2 %-104.3 % with the relative standard deviations below 8.1 % compared to a standard QuEChERS-based method. The lower limits of quantification for 4 neonicotinoids in bananas were below 5 ng g−1, lower than the standard method and the maximum residue levels in China and the European Union. This work clarifies the characteristics, rules and performance of the sampling-rate calibration and equilibrium calibration, which is of crucial importance for the development and application of in vivo SPME. The developed method is convenient, sensitive, and accurate for the determination of pesticide residues, which is of great significance to guide the safe use of pesticides in the field and prevent products with excessive pesticide residues from entering the market. [ABSTRACT FROM AUTHOR]

Aqueous mode size exclusion chromatography (SEC) was employed for the analysis and construction of molecular weight (MW) calibration curves of three water-soluble polymers, namely, polyethylene glycol, polyethylene oxide, and polyacrylic acid sodium salt. Several calibration curves were obtained, varying chromatographic conditions such as columns arrangement, ionic strength, temperature and pH, in addition trends in polymeric chromatographic behavior were examined. The variation in SEC distribution coefficients at different temperatures was found to be below 10 %, indicating that the studied polymers follow an ideal SEC mechanism under the tested conditions. Thus, differences in chromatographic behavior were ascribed to changes in polymer configuration induced by media and/or temperature. These variations in morphology were consistent with the observed SEC behavior. Regarding MW calibration, polynomial regression models ranging from first to fifth order were applied, and the most adequate ones were selected based on their fit and prediction capabilities. Third order polynomials were the preferred models for polyethylene glycol and polyacrylic acid sodium salt, independently of chromatographic conditions. Meanwhile for polyethylene oxide, either third or fifth-order polynomial models were optimal depending on the chromatographic conditions. All the selected regression models presented coefficients of multiple determination (R 2 ) above 0.990, while achieving relative errors of prediction (REP%) in MW ranging from 0.3 to 4 % for cross-validation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

• Automated framework for parameter estimation of multi-component ion exchange chromatography models. • Model-based optimization of a purification included in the framework. • Experimental validation of the model using the obtained optimum. • Several options for optimal purification provided to the user. The current landscape of biopharmaceutical production necessitates an ever-growing set of tools to meet the demands for shorter development times and lower production costs. One path towards meeting these demands is the implementation of digital tools in the development stages. Mathematical modelling of process chromatography, one of the key unit operations in the biopharmaceutical downstream process, is one such tool. However, obtaining parameter values for such models is a time-consuming task that grows in complexity with the number of compounds in the mixture being purified. In this study, we tackle this issue by developing an automated model calibration procedure for purification of a multi-component mixture by linear gradient ion exchange chromatography. The procedure was implemented using the Orbit software (Lund University, Department of Chemical Engineering), which both generates a mathematical model structure and performs the experiments necessary to obtain data for model calibration. The procedure was extended to suggest operating points for the purification of one of the components in the mixture by means of multi-objective optimization using three different objectives. The procedure was tested on a three-component protein mixture and was able to generate a calibrated model capable of reproducing the experimental chromatograms to a satisfactory degree, using a total of six assays. An additional seventh experiment was performed to validate the model response under one of the suggested optimum conditions, respecting a 95 % purity requirement. All of the above was automated and set in motion by the push of a button. With these results, we have taken a step towards fully automating model calibration and thus accelerating digitalization in the development stages of new biopharmaceuticals. [ABSTRACT FROM AUTHOR]

We present a new chromatogram decomposition method for Gas Chromatography (GC) which represents a chromatogram as a sum of template functions inspired by the analytic solution of mass balance equation. The proposed method starts by approximating GC response of a single gas by these template functions. Consequently, it utilizes the temporal translation and dilation of this approximate response to approximate GC responses of other gases of interest. The results are demonstrated on lab data using calibration bottles containing mixtures of C 1 - C 5. Correlation of the amplitudes of the decomposed responses and injected concentrations indicates linear calibration curves are sufficient to estimate C 1 - C 5 concentrations. The performance of the method is demonstrated by a ratio test where a calibration bottle with C 1 concentration 300 times larger than C 2 and C 3 concentrations is injected into GC. • Expressing response of a GC system to a single gas using functions inspired by the analytic solution of a mass balance equation. • Approximating responses of a GC system to other gases as an affine transformed version of response of the single gas. • Calibration and subsequent quantitative analysis with an application for sensitivity analysis. [ABSTRACT FROM AUTHOR]

The limit of detection (LOD) is a crucial measure in analytical methods, representing the smallest amount of a substance that can be distinguished from background noise. In the realm of gas chromatography (GC), however, determining LOD can be quite subjective, leading to significant variability among researchers. In this study, we validate the Hubaux-Vos method, an International Standards Organization(ISO)-approved approach for determining LOD in gas concentration measurements, using a GC equipped with a discharge ionization detector (DID) and a dynamic dilution system. We employ a gas mixture certified reference material (CRM) of CO, CH 4 , and CO 2 at various concentrations to generate calibration curves for each gas. Subsequently, we estimate the LODs for each gas using the Hubaux-Vos method. Surprisingly, our findings indicate a notable difference between the LODs calculated using the Hubaux-Vos method and those confirmed through experiments. This highlights the importance of critically examining the theoretical foundations of LOD determination. We strongly recommend researchers to scrutinize the principles guiding LOD determination. The method proposed in this study offers an effective way to rigorously validate theoretical approaches for estimating LODs in gas concentration measurements using GC., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

• Sample brought directly in thermal desorption tube without adsorbent. • Proper calibration is not evident since it can't be done in similar way as sample. • Calibration issues were investigated using offline and inline liquid calibration. • Problem could be attributed to diluent (illustrated with water and toluene). • Insertion of LiCl plug in thermal desorber tube to remove water offered solution. A thermal desorber (TD) can be used in different ways to introduce samples in a gas chromatographic (GC) system. Besides its conventional use where the collected analytes are released from the sorbent in the sample tube, direct dynamic desorption (DDD) is an interesting option where a solid sample is put directly in the TD tube. However, since no sorbent is used for the sample, proper calibration is not straightforward. This issue was investigated in the present work using offline liquid calibration (OLC) and inline liquid calibration (ILC). Unexpectedly, ILC yielded a lower response than OLC. This could be related to the adsorption kinetics of the analytes and water on the cold trap of the TD. More insight was gained performing double injection ILC experiments with toluene as diluent for the analytes and injecting water before or after the toluene solution. This revealed a clear influence of the diluent. The influence of water was further explored applying two cold trap temperatures (4 °C and −30 °C). Inserting a LiCl trap in the TD tube to capture the water was found to be an effective solution for the problem. Finally, quantitative aspects of this approach were demonstrated. [ABSTRACT FROM AUTHOR]

• Importance of sufficient ionic strength (buffer capacity) of LC–MS mobile phases. • Improving chromatographic peak shape of ionic analytes. • Analyte response as a function of modifier concentration in LC–MS mobile phase. • Chromatographic peak splitting due to the presence of matrix compounds. • Aging of liquid chromatography stationary phases. A routine multiresidue method developed for the detection and quantification of veterinary drug residues in animal-based food was used to analyze sheep (ovine) liver. Unlike when working with previously validated matrices (e.g., bovine liver), some of the analytes of interest chromatographed in the form of split- or even fully baseline separated peaks. In other cases a significantly longer retention times (tR) was observed. A detailed investigation led to the elucidation of taurocholic acid as the causative agent. This compound is present in sheep liver at significantly higher concentrations than in most other animal tissues. Taurocholic acid is a zwitterionic compound and likely acts as an ion pairing agent, which modifies the selectivity of the stationary phase in a highly spatial and dynamic way. Injecting smaller volumes of matrix extract or the use of a significantly higher formic acid concentration in the mobile phase reduced or even completely eliminated the peak splitting. A more detailed examination led to the observation that the problem is not restricted to this particular matrix and extraction procedure or the used stationary phase. In fact, a higher formic acid concentration (e.g., 1.0 % versus 0.1 %) significantly improves the peak shape of many analytes present in fortified matrix samples as well as in pure standard solutions. In addition, analytical column aging was observed as being slower with a higher formic acid concentration. Finally the peak shape of analytes interacting with the metallic parts along the flow path of the liquid chromatograph was also significantly improved. Use of 0.1 % acid in mobile phases is often taken for granted in LC-MS. Regardless of the stationary phase, a higher ionic strength better stabilizes the pH and reduces unwanted interactions, which ultimately improves the method robustness. Flow injection experiments often show that 0.1 % acid concentrations produce the highest analyte signals. Yet, the use of 1 % acid in the mobile phase often leads to narrower and therefore taller chromatographic peaks, which may lead to lower detection limits for many analytes and to an improved separation efficiency. [ABSTRACT FROM AUTHOR]

• The risk of bisphenols (BPA, BPF, and BPS) in thermal papers and canned food samples was assessed. • A method for determining bisphenols based on HPLC-DAD was developed and validated. • An integrated calibration method was modified and supported by the H-point standard addition method to compensate interference effects. • BPA concentration in canned food products was exceeded. • Risk factors connected to the receipts (BPF and BPS) proved harmful to cashiers due to long exposure time. The most crucial purpose of the measurement is to obtain a reliable result that reflects the actual qualitative and/or quantitative features of the tested material. The overriding goal of analytical chemistry is to obtain accurate results after compensating of various interference effects as well as non-linear calibration dependence. A new approach based on an integrated calibration method (ICM) supported by H-point standard addition method (HPSAM) has been used to improve the quality of analytical results. The proposed methodological approach was extended using the step-by-step dilution procedure, and five measurement conditions were used to eliminate multiplicative, additive, and non-linear interferences. On this basis, a set of estimations is obtained to improve the quality of the analytical results. The analytical usefulness of the proposed approach was tested on the example of the determination of three compounds from the group of bisphenols (BPs) using the chromatographic technique - HPLC-DAD (high-performance liquid chromatography with diode array detection). Compared to the reference method - fluorescence spectroscopy - the obtained results were characterized by excellent accuracy (RE=3 % in most cases). The developed methodology allowed to carry out a risk assessment on BPA, BPF, and BPS present in samples of shop receipts and canned food. Store clerks have been shown to be particularly vulnerable to PBF and BPS in receipts due to skin permeation (exposure factors were equal to 308.97 µg/g for BPF and 181.89 µg/g for BPS). Consumers should also pay close attention to the BPA found in canned food samples (the average concentration was equal to 20.61 µg/mL, and the tolerable daily intake was exceeded over 165.000 times). The analytical method and the methodological approach were evaluated using the RGB model and the AGREE approach - it was shown that the method can be successfully used for other analytical purposes (the method is White) and is environmentally friendly (Significance=0.63). [ABSTRACT FROM AUTHOR]

Many applications in laboratory, industrial and R&D practice involve utilization of standard chemical vapor mixtures, therefore their availability, ease of preparation and reliability play a crucial role. This work is presenting a new instrumentation based on the innovated dynamic preparation method using the injection of liquid sample, fast evaporation, and uniform mixing with carrier gas. The combination of precise syringe drives, quantitative evaporation and controlled flow of carrier gas provides very high level of accuracy and stability of the generation process. The system is robust with minimal requirements for calibration, and it is suitable for producing single or multi component mixtures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Raman spectroscopy is considered a Process Analytical Technology (PAT) tool in biopharmaceutical downstream processes. In the past decade, researchers have shown Raman spectroscopy's feasibility in determining Critical Quality Attributes (CQAs) in bioprocessing. This study verifies the feasibility of implementing a Raman-based PAT tool in Protein A chromatography as a CQA monitoring technique, for the purpose of accelerating process development and achieving real-time release in manufacturing. A system connecting Raman to a Tecan liquid handling station enables high-throughput model calibration. One calibration experiment collects Raman spectra of 183 samples with 8 CQAs within 25 h. After applying Butterworth high-pass filters and k-nearest neighbor (KNN) regression for model training, the model showed high predictive accuracy for fragments (Q 2 = 0.965) and strong predictability for target protein concentration, aggregates, as well as charge variants (Q 2 ≥ 0.922). The model's robustness was confirmed by varying the elution pH, load density, and residence time using 19 external validation preparative Protein A chromatography runs. The model can deliver elution profiles of multiple CQAs within a set point ± 0.3 pH range. The CQA readouts were presented as continuous chromatograms with a resolution of every 28 s for enhanced process understanding. In external validation datasets, the model maintained strong predictability especially for target protein concentration (Q 2 = 0.956) and basic charge variants (Q 2 = 0.943), except for overpredicted HCP (Q 2 = 0.539). This study demonstrates a rapid, effective method for implementing Raman spectroscopy for in-line CQA monitoring in process development and biomanufacturing, eliminating the need for labor-intensive sample pooling and handling., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

A novel method for the determination of per- and polyfluoroalkyl substances (PFAS) in groundwater is presented using a subsample, matrix-matched calibrators, 96-well plate solid phase extraction (SPE), and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Accuracy, precision, measurement of uncertainty (MOU), method detection limit (MDL), method quantitation limit (MQL), analytical measurement range, interferences/ion suppression, and analyte stability were determined as part of the in-house method validation. The method quantitates 42 PFAS compounds from nine different compound classes. Accuracy for the reference material (RM) and matrix spike (MS) ranged from 52.3 to 117.8 %, and precision for the MS and matrix spike duplicate (MSD) had a coefficient of variation (CV) from 2.0 % to 23.3 %. MDLs spanned from 0.07 to 1.97 ng L -1 , with MQLs ranging from 0.20 to 5.90 ng L -1 . Suppression studies determined that iron and manganese have effects on analytes that do not have paired isotopically labeled standards. The results from the in-house validation indicated that this Michigan Department of Health and Human Services laboratory developed test meets the necessary accuracy, precision, MDL, MQL and reporting limits requirement established by the laboratory's quality system essentials (QSEs) and select criteria from the Department of Defense (DoD) Quality Systems Manual for Environmental Laboratories and American Industrial Hygiene Association Laboratory Accreditation Program, LLC (AIHA LAP, LLC) accrediting International Standard Organization (ISO/IEC 17025:2017) check list., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)