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• A filter paper chad was used to extract explosive residues from vapor samples. • The extracted explosives were analysed via Lab on a Chip. • Results between vapor and liquid samples were compared. • A new promising method to detect explosives in the headspace is described. The detection and analysis of explosives and explosive-related compounds is a heightened priority in recent years for homeland security and counter-terrorism applications. This study aimed to evaluate the use of a commercial Lab-On-a-Chip (LOC) instrument for the analysis of explosive vapours, with the long-term goal of developing a portable instrument for passively detecting explosives in air samples. A simple method to collect explosive vapour residues was developed using a glass vial containing varying amounts of the target explosives (1 mg/mL). Standards were diluted to the desired concentration in 150 μL of acetone to facilitate the evaporation. The top of the vial was covered with a circular 0.5 cm diameter filter paper and exposed to a range of temperatures from 22 °C to 80 °C for 15 min. Following evaporation, the filter paper chads were folded and inserted into the LOC wells containing the separation buffer for the analysis, avoiding any further extraction step. After successfully separating and detecting eight explosives via liquid analysis, three explosives were chosen as targets for the vapour analysis experiments. 1,3,5-Trinitrobenzene (TNB), 2,4,6-Trinitrotoluene (TNT), and 2,4,6-Trinitrophenylmethylnitramine (Tetryl) were successfully separated, detected and identified following the vapour extraction of explosive standards onto filter paper chads. Limits of detection for the liquid analysis were demonstrated to be 2.32 ng for TNB, 2.35 ng for Tetryl, and 3.25 ng for TNT. The minimum detectable mass found for the vapour analysis was 6.03 for TNB, 9.99 ng for TNT, and 14.22 ng for Tetryl. The average recovery from the paper chads was 29% for Tetryl, 47% for TNB, and 75% for TNT (n = 4), comparable with findings from previous studies. Results show that a minimum temperature of 40 °C is necessary to vaporize the compounds using acetone, while the best results were achieved when heating the vial to 80 °C. The use of a filter paper to collect the explosives residues, avoiding any additional extraction step, and the ability to analyze these compounds using a LOC instrument, makes this approach a future alternative method for explosive residues detection in the headspace. [ABSTRACT FROM AUTHOR]

• Modification of cellulose paper by in situ synthesis of metal-organic framework-5. • Bonding between functional groups on cellulose paper with organic ligand. • Cellulose/MOF-5 was used in the thin film solid-phase microextraction method. • Thin film showed a good ability to extraction of selective drugs in urine samples. • The method is effective, sensitive, cost-effective and have wide LDRs and low LODs. This work, reports the successful preparation a thin film by a simple and inexpensive process for quantification of a model analytes in the urine sample using HPLC-UV. To this end, cellulose paper was employed as a substrate for the in-situ synthesis of MOF-5, to increase the resistance of the prepared film. The prepared film can be reused 26 times with no reduction in its performance. The thin film prepared by MOF-5 modified cellulose substrate was utilized in thin film microextraction (TFME) method for the extraction and preconcentration of naproxen, aspirin, tolmetin, and celecoxib. Under optimal conditions, the linear dynamic range of the target analytes was 2–500 µg L −1 with correlation coefficients (R2) ranging from 0.9961 to 0.9990. Also, the limits of detection (LODs), the limits of quantification (LOQs) and relative standard deviation (RSD%) of the proposed method for selected analytes ranged between 0.57 and 0.77 µg L −1, 1.7 to 2.3 and 3.5 % to 6.2 %, respectively. Moreover, relative recoveries varied from of 94 % to 108 %, indicating the absence of matrices effect in the proposed method. Eventually, the TFME was successfully used for the extraction of selected analytes from urine samples. [ABSTRACT FROM AUTHOR]

• The applications of immobilized biomaterials in herbal analysis are reviewed. • Different immobilization strategies for biomaterials are discussed. • The carrier materials applied in biomaterials immobilization are summarized. Immobilization of biomaterials developed rapidly due to the great promise in improving their stability, activity and even selectivity. In this review, the immobilization strategies of biomaterials, including physical adsorption, encapsulation, covalent attachment, cross-linking and affinity linkage, were briefly introduced. Then, the major emphasis was focused on the reported various types of immobilized biomaterials, including proteins, enzymes, cell membrane and artificial membrane, living cells, carbohydrates and bacteria, used in the herbal analysis for bioactive compound screening, drug-target interaction evaluation and chiral separation. In addition, a series of carrier materials applied in biomaterials immobilization, such as magnetic nanoparticles, metal-organic frameworks, silica capillary column, cellulose filter paper, cell membrane chromatography, immobilized artificial membrane chromatography and hollow fiber, were also discussed. Perspectives on further applications of immobilized biomaterials in herbal analysis were finally presented. [ABSTRACT FROM AUTHOR]

Baby wipes and wet toilet paper are specific hygiene care daily products used on newborn and children skin. These products may contain complexes mixtures of harmful chemicals. A method based on pressurized liquid extraction (PLE) followed by gas chromatography-mass spectrometry (GC-MS) has been developed for the simultaneous determination of sixty-five chemical compounds (fragrance allergens, preservatives, musks, and phthalates) in wipes and wet toilet paper for children. These compounds are legislated in Europe according Regulation EC No 1223/2009, being twelve of them banned for their use in cosmetics, and one of them, 3-iodo-2-propynyl butylcarbamate (IPBC), is banned in products intended for children under 3 years. Also, propyl-, and butylparaben will be prohibited in leave-on cosmetic products designed for application on the nappy area of children under 3 years from April 2015. PLE is a fast, simple, easily automated technique, which permits to integrate a clean-up step during the extraction process reducing analysis time and stages. The proposed PLE-based procedure was optimized on real non-spiked baby wipe samples by means of experimental design to study the influence on extraction of parameters such as extraction solvent, temperature, extraction time, and sorbent type. Under the selected conditions, the method was validated showing satisfactory linearity, and intra-day, and inter-day precision. Recoveries were between 80–115% for most of the compounds with relative standard deviations (RSD) lower than 15%. Finally, twenty real samples were analyzed. Thirty-six of the target analytes were detected, highlighting the presence of phenoxyethanol in all analyzed samples at high concentration levels (up to 0.8%, 800 μg g −1 ). Methyl paraben (MeP), and ethyl paraben (EtP) were found in 40-50% of the samples, and the recently banned isobutyl paraben (iBuP) and isopropyl paraben (iPrP), were detected in one and seven samples, respectively, at concentrations between 0.093 and 247 μg g −1 . In the case of phthalates, the forbidden phthalates dibutyl phtalate (DBP) and di(2-ethylhexyl)phthalate (DEHP) were also found in thirteen samples at low levels. All the samples contained fragrance allergens in many cases at high levels (up to 2400 μg g −1 ) and three musks were detected in the samples. Excluding the banned compounds, all samples complied with the concentration limits established by the European Regulation although 25% of them did not fulfill the labeling requirements for fragrance allergens. [ABSTRACT FROM AUTHOR]

• An alternative elution mode to conventional HPLC to separate compounds by class. • Sequential elution was utilized to separate classes of compounds in under 15 min. • A tandem-column stationary phase combination (SAX and C18) was utilized. • SAX+C18 and C18+SAX column orientations yielded nearly identical separations. • Retention time and peak area precision were below 1.5 % RSD. This paper discusses the development of an analytical method by an alternative separation approach, sequential elution liquid chromatography (SE-LC), to separate permanently charged ions (anions), weak acids, and neutral compounds using anion exchange and reversed-phase columns in tandem. SE-LC separates classes of compounds by group by employing two or more elution modes. Advantages to using SE-LC over conventional HPLC are a greater peak capacity and a reduced separation disorder. Importantly, the same HPLC as used for a conventional HPLC separation may be used to afford a successful SE-LC separation. Mobile phase selection and gradient optimization are integral for a successful SE-LC class separation of permanent anions, weak acids, and neutral compounds and will be discussed in detail in this paper. The most successful (best resolution and repeatability) SE-LC separation was achieved by applying isocratic elution at low pH to elute the weak acids, followed by an acetonitrile gradient to elute the neutral compounds, and last a sodium methanesulfonate gradient to elute the anionic compounds using a superficially porous C18 column coupled with a strong anion exchange (SAX) column. Repeatability (RSD) in the retention times and peak areas of the analytes was less than 0.25 % and 1.5 %, respectively. [ABSTRACT FROM AUTHOR]

• A data-driven model for reversed phase selectivity is established. • A revised hydrophobic subtraction model is proposed. • Accurate predictions of isomer selectivity are made. Reversed-phase (RP) liquid chromatography is an important tool for the characterization of materials and products in the pharmaceutical industry. Method development is still challenging in this application space, particularly when dealing with closely-related compounds. Models of chromatographic selectivity are useful for predicting which columns out of the hundreds that are available are likely to have very similar, or different, selectivity for the application at hand. The hydrophobic subtraction model (HSM1) has been widely employed for this purpose; the column database for this model currently stands at 750 columns. In previous work we explored a refinement of the original HSM1 (HSM2) and found that increasing the size of the dataset used to train the model dramatically reduced the number of gross errors in predictions of selectivity made using the model. In this paper we describe further work in this direction (HSM3), this time based on a much larger solute set (1014 solute/stationary phase combinations) containing selectivities for compounds covering a broader range of physicochemical properties compared to HSM1. The molecular weight range was doubled, and the range of the logarithm of the octanol/water partition coefficients was increased slightly. The number of active pharmaceutical ingredients and related synthetic intermediates and impurities was increased from four to 28, and ten pairs of closely related structures (e.g., geometric and cis -/ trans - isomers) were included. The HSM3 model is based on retention measurements for 75 compounds using 13 RP stationary phases and a mobile phase of 40/60 acetonitrile/25 mM ammonium formate buffer at pH 3.2. This data-driven model produced predictions of ln α (chromatographic selectivity using ethylbenzene as the reference compound) with average absolute errors of approximately 0.033, which corresponds to errors in α of about 3 %. In some cases, the prediction of the trans -/ cis - selectivities for positional and geometric isomers was relatively accurate, and the driving forces for the observed selectivity could be inferred by examination of the relative magnitudes of the terms in the HSM3 model. For some geometric isomer pairs the interactions mainly responsible for the observed selectivities could not be rationalized due to large uncertainties for particular terms in the model. This suggests that more work is needed in the future to explore other HSM-type models and continue expanding the training dataset in order to continue improving the predictive accuracy of these models. Additionally, we release with this paper a much larger data set (43,329 total retention measurements) at multiple mobile phase compositions, to enable other researchers to pursue their own lines of inquiry related to RP selectivity. [ABSTRACT FROM AUTHOR]

• Method developed for PFAS in various food matrices. • Limit of quantification for 4 regulated EFSA PFAS in the lower ng/kg range achieved. • The method can also be used for food contact materials. • The method was applied to food contact material, seaweed samples, eggs and milk. Dietary intake is the major pathway of human exposure to per- and polyfluoroalkyl substances (PFAS). Due to their generally very low concentrations in food, especially for foods of plant origin, and their toxicological relevance, demand is growing for improved selective and sensitive analytical methods for the determination of PFAS in the lower ng/kg range. The relevance is pointed out due to the fact that the European Commission has published limits of quantification (LOQs) in the lower ng/kg range for different food matrices in Recommendation (EU) 2022/1431 on the monitoring of perfluoroalkyl substances in food. For example, LOQs of 2 ng/kg for perfluorooctanesulfonic acid (PFOS), 1 ng/kg for perfluorooctanoic acid (PFOA), 1 ng/kg for perfluorononanoic acid (PFNA) and 4 ng/kg for perfluorohexanesulfonic acid (PFHxS) in fruit, vegetables and baby foods are required. A new, very sensitive method is presented here for the determination of 22 PFAS in food and food contact materials. The method is based on liquid-solid extraction and automated clean-up using two solid phase extraction techniques. The analytes are separated and detected by HPLC-MS/MS. A limit of detection (LOD) of 0.33 ng/kg and an LOQ of 1.0 ng/kg are attained for plant foods such as fruits and vegetables as well as for milk and baby food. For foods of animal origin such as egg, meat, fish and paper-based food contact materials an LOD of 1.6 ng/kg as well as an LOQ of 5.0 ng/kg are attained. PFOS and PFOA were the most abundant compounds in the food samples with concentration as high as 1,051 ng/kg of PFOA in sea weed samples and 772 ng/kg of PFOS in eggs samples. In food contact material samples, higher levels were found with a maximum of 310,000 ng/kg PFHxA. In sum the presented method firstly allows determination of PFAS in a wide variety of foodstuffs and paper-based food contact materials at EU-required concentration ranges. [ABSTRACT FROM AUTHOR]

• Paper-based isoelectric focusing was applied to the separation and fractionation of amino acids. • Ampholytes were used to form a pH gradient in the folding paper. • Formation of a pH gradient was confirmed using pH indicators. • HPLC confirmed the separated amino acids following extraction from the paper. We demonstrated the fractionation of two amino acids, glutamic acid and histidine, separated via isoelectric focusing (IEF) on filter paper folded and stacked in an origami fashion. Channels for electrophoresis were fabricated as circular zones acquired via wax printing onto the filter paper. An ampholyte solution with amphiphilic samples was deposited on all the circle zones, which was followed by folding to form the electrophoresis channels. IEF was achieved by applying an electrical potential between the anodic and cathodic chambers filled with phosphoric acid and sodium hydroxide solutions, respectively. A pH gradient was formed using either a wide-range ampholyte with a pH of 3 to 10 or a narrow-range version with a pH of 5 to 8, which was confirmed by adding pH indicators to each layer. The origami IEF was used to separate the amino acids, glutamic acid and histidine, by mixing with the ampholytes, which were deposited on the layers. The components in each layer were extracted with water and measured by high-performance liquid chromatography using pre-column derivatization with dansyl chloride. The results indicated that the focus for glutamic acid and that for histidine were at different layers, according to their isoelectric points. The origami isoelectric focusing achieved the fractionation of amino acids in less than 3 min using voltage as low as 30 V. [ABSTRACT FROM AUTHOR]

• Disposable diapers contain toxic compounds as PAHs. • There are no harmonized analytical methods for the determination of PAHs in diaper. • A protocol for determination of PAHs using cryogenic grinding and LLE is presented. • There was no diaper that is free of PAHs compounds. In this paper we demonstrate the development of the extraction procedure of polycyclic aromatic hydrocarbons from baby diapers along with their quantification by gas chromatography-mass spectrometry. Apart from covering plastic foil, disposable baby diapers contain sorbents intended to absorb urine and feces. A hygroscopic, adsorptive, and tough-to-homogenize fibrous sorbent, represents an analytical challenge to analytical chemists. To address this issue we optimized and validated a novel extraction protocol including cryogenic homogenization, liquid-liquid extraction and further preconcentration by evaporation. By using deuterated internal standards in conjunction with matrix-matched calibration, high precision and accuracy were achieved. The limit of detection is estimated in the range of 0.041–0.221 ng/g (for fluorene and fluoranthene, respectively), which is far below the concentration currently assumed to be dangerous for children. The method was successfully applied to real samples available on the Polish market, and it was found that the amount of PAH compounds varies between manufacturers. Most diapers do not have all 15 polycyclic aromatic hydrocarbons in their composition, but there is no diaper that is free of these compounds. The most abundant in diapers was acenaphthalene, where the concentration ranged from 1.6 ng/g diaper up to 362.4 ng/g. The lowest concentration in diapers is chrysene, which is not detected in most diapers. The article is a response to the lack of a harmonized analytical method for the determination of polycyclic aromatic hydrocarbons in disposable sanitary products for children. [ABSTRACT FROM AUTHOR]

• Dimethyl carbonate is tested as green alternative to acetonitrile. • Dimethyl carbonate is slightly soluble in water, but it has high elution strength. • Dimethyl carbonate and acetonitrile showed comparable kinetic performance. Nowadays, environmental problems are drawing the attention of governments and international organisations, which are therefore encouraging the transition to green industrial processes and approaches. In this context, chemists can help indicate a suitable direction. Beside the efforts focused on greening synthetic approaches, currently also analytical techniques and separations are under observation, especially those employing large volumes of organic solvents, such as reversed-phase liquid chromatography (RPLC). Acetonitrile has always been considered the best performing organic modifier for RPLC applications, due to its chemical features (complete miscibility in water, UV transparency, low viscosity etc); nevertheless, it suffers of severe shortcomings, and most importantly, it does not fully comply with Environmental, Health and Safety (EHS) requirements. For these reasons, alternative greener solvents are being investigated, especially easily available alcohols. In this work, chromatographic performance of the most common solvents used in reversed-phase chromatography, i.e., acetonitrile, ethanol and isopropanol, have been compared to a scarcely used solvent, dimethyl carbonate (DMC). The analytes of interest were two small molecules, caffeine and paracetamol, whose kinetics and retention behaviour obtained with the four solvents have been compared, and all contributions to band broadening have been assessed. Results about kinetic performance are very promising, indicating that a small amount (7 % v/v) of DMC is able to produce the same efficiency as a 2.5-times larger ACN volume (18 % v/v), and larger efficiency than alcohols. This paper reports, for the first time, fundamental studies concerning the mass transfer phenomena when DMC is used as an organic solvent in RPLC, and, together with the companion paper, represents the results of a research whose final aim was to discover whether DMC is suitable for chromatographic applications both in linear and preparative conditions. [ABSTRACT FROM AUTHOR]

• PAHs in PM2.5 were analyzed by thermal desorption GC-MS. • Analyte protectant reduced the decomposition and adsorption of PAHs. • The surfactant was used as a thermal extraction aid. • The auxiliary agent improved the analytical sensitivity of thermal desorption GC-MS Thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) is used to analyze polycyclic aromatic hydrocarbons (PAHs) in atmospheric fine particulate matter. However, despite the high sensitivity of TD-GC-MS, the recovery rate of PAHs is greatly influenced by active sites in the equipment. PAHs are decomposed or adsorbed at active sites, decreasing quantitative accuracy. Also, the thermal extraction of PAHs is easily affected by the matrix in PM2.5 samples, decreasing the thermal extraction efficiency. Herein, the analytical sensitivities of PAHs were improved by adding analyte protectant (AP) and thermal desorption aid (TDA) as an auxiliary agent. The combination of 2 µL of 0.5 w/v% D-sorbitol (as AP) and 2 µL of 10 w/v% Tween®20 (as TDA) was found to be most effective in improving the analytical sensitivity of PAHs. The sensitivities of 5–6-ring PAHs with high boiling points increased most when analyzing blank filter papers added with PAHs standard sample or real samples of PM2.5 compared with the samples without the auxiliary agent. When analyzing real samples of PM2.5, the peak areas of 5-ring and 6-ring PAHs in the PM2.5 sample added with the optimized auxiliary agent were 1.40 and 1.96 times that without the auxiliary agent. It is considered that AP in the auxiliary agent covered active sites and protected PAHs undergoing decomposition or adsorption. TDA improved the thermal extraction rate of high boiling point PAHs. When using alternative heat sampling equipment to analyze low concentrations of high boiling point components, the auxiliary agent proposed herein can increase the analytical sensitivity toward the target compounds. [ABSTRACT FROM AUTHOR]

• The impact of lateral flow induced by AC electroosmotic flow on Taylor dispersion was studied in rectangular micro-channels with critical dimension of 3 µm. • Generalized dispersion theory was used to evaluate and predict Taylor dispersion with wall retention. • The influence of aspect ratio, retention, diffusion coefficient and potential was studied. Axial dispersion in chromatographic columns is responsible for a reduced separation efficiency. In the present research macrotransport theory is used to predict the phenomenological constants related to axial dispersion. We evaluate the efficacy of lateral flow induced by alternating current (AC) in the presence of retaining walls on the separation resolution. Results show that lateral flows induced by laterally applied potentials as low as 0.3 V reduce C-term dispersion by a factor of 5.0 for unretained conditions (k = 0) and 2.7 for retained (k = 5) conditions, with a diffusion coefficient (D m) of 10–11m2/s. The present paper further contributes to the understanding of the use of secondary lateral flows for dispersion reduction and offers practical guidance for designing future vortex chromatographic columns. It appears that a maximal performance gain is attained at low aspect ratios (AR=1), with the gain reduced from a factor of 5 to 1.6 for AR=4 for unretained conditions, and from 2.7 to 1.4 for retained conditions (k = 5) [ABSTRACT FROM AUTHOR]

• Early prognosis of neuroblastoma in infants must be a priority to act against it asap. • The neuroblastoma prognosis can based on the study of catecholamines metabolites from urine. • Catecholamine metabolites from baby pee-covered diapers were detected by CE-UV. • Disposable diapers were employed as sampling devices to collect the urine. • The variables of the sample preparation step were optimized and the method was validated. A method has been developed for the analysis of vanillylmandelic acid, homovanillic acid, and 5-hydroxyindoleacetic acid from baby urine as biomarkers of neuroblastoma in infants. Disposable diapers were employed as sampling devices in order to guarantee a low invasiveness during this step. The proposed method consists on a simple extraction step with water from the used diaper followed by the measurement using capillary electrophoresis with UV detection. The Box-Behnken design (BBD) was utilized to optimize the process of extracting catecholamine metabolites from the examined samples. The variables of the sample preparation step were optimized and the method was validated obtaining limits of quantification of 1.65 μg mL−1, good intraday and inter-day precision with RSDs under 15 %. Finally the method was applied to real samples collected from the Department of Neonatology, University Clinical Centre (Gdańsk, Poland). The greenness of the proposed method was also evaluated with different tools (i.e., AGREEPrep and GAPI) with satisfactory results, which allow to state that the method can be considered green. Moreover, its practicality was evaluated by application of BAGI tool, proving to be a practical and economical method to be applied in routine laboratories for determination of catecholamine metabolites in urine-type samples. [ABSTRACT FROM AUTHOR]

• SFE of plastic additives is best achieved in dense CO 2 conditions. • Comparison of extraction methods shows good performance of SFE. • SFE-SFC-MS avoids significant laboratory contaminations. • SFE-SFC-MS reduces analysis time, solvent and consumables. • Transferring a compressible fluid ensures minimal band broadening. Plastic additives are introduced in plastic material formulations, along with organic polymers, to offer different properties such as stability, plasticity or color. However, plastic additives may migrate from the plastic material to the content (in case of plastic containers) or to the material in contact with the plastic, like human skin. In the case of plastic medical devices, this migration is of particular interest, as plastic additives may be deleterious to health. In the present paper, we examined the interest of combining supercritical fluid extraction (SFE) to supercritical fluid chromatography (SFC) hyphenated to mass spectrometry (MS) in an online system to characterize plastic additives in laboratory gloves, taken as samples of medical devices. A set of target compounds comprising 18 plasticizers, 4 antioxidants and 2 lubricants was defined and their detectability with MS was examined, where it appeared that electrospray ionization (ESI) provided better detectability than atmospheric pressure chemical ionization (APCI). After examining possible stationary phases with the help of Derringer desirability function, an isocratic chromatographic method (CO 2 :methanol 95:5) was developed on Shim-pack UC Phenyl column. The extraction method was examined with a 3-level full factorial design of experiments to optimize the extraction temperature (40 °C) and pressure (200 bar). The online SFE-SFC-MS method was compared to offline methods where the samples were extracted with liquid solvents at atmospheric pressure or high pressure then analysed with SFC-MS. In all cases, offline methods showed significant contaminants (like the oleamide lubricant) issuing from laboratory plastic materials as nitrogen drying station, syringes and filters, while the online method allowed a complete elimination of laboratory contaminations. Furthermore, the online method saved time, solvents and laboratory consumables. It will also show that transferring a compressible fluid from a loading loop is favourable to high efficiency, as the resulting chromatographic peaks are much thinner than when transferring a liquid. Compared to injecting liquid heptane, the efficiency increase was 3.4-fold, while compared to injecting liquid methanol (a common practice in SFC), the efficiency increase was 13-fold. Finally, the additive composition of different laboratory gloves was compared. [ABSTRACT FROM AUTHOR]

• Determination of the specific surface area of biomass activated carbon by HS-GC technique. • Mathematical model proves the relationship between tracer and specific surface area value. • The present method is simple, efficient, and can be used for batch sample testing. This paper introduces a method for determining the specific surface area (SSA) of biomass activated carbon (BAC) using a tracer-based headspace gas chromatography (HS-GC) technique. The method relies on the adsorption equilibrium of methanol on BAC samples at elevated temperature. A mathematical model allows for the calculation of SSA from the methanol signal obtained during the headspace analysis. The results demonstrate high precision (relative standard deviation < 2.44%) and strong accuracy (correlation with the conventional BET-N 2 adsorption method, R² = 0.986). This method offers several advantages over traditional techniques, including ease of operation, significant time efficiency, and the the ability to perform batch determinations of SSA, as multiple samples can be processed simultaneously during the phase equilibrium step. [ABSTRACT FROM AUTHOR]

• Two amphiphilic dendritic organic small molecule gel stationary phases were prepared. • Some shape-restricted isomers and cis-trans isomers were successfully separated. • The two stationary phases prepared exhibited high molecular shape selectivity. • SiO 2 @PAE-PA and SiO 2 @PAE-ANT have RPLC/HILIC hybrid mode properties for HPLC. • Modulation of hydrophilic/hydrophobic balance alters molecule recognition ability. Geometric isomers tend to have similar polarities and differ only in molecular shape. Vigorously developing new stationary phases to meet the requirements for the separation of isomers that have similar physicochemical properties is still an urgent topic in separation science. Poly (arylene ether)-based dendrimers are known for their multifunctional branched peripheral structures and high self-assembly properties. In this paper, two amphiphilic dendritic organic small molecule gelling agents based on poly (aryl ether), PAE-ANT and PAE-PA, were prepared and conjugated to the silica surface. SiO 2 @PAE-ANT and SiO 2 @PAE-PA were used as HPLC stationary phases for the separation of non-polar shape-restricted isomers. Both stationary phases have very high molecular shape selectivity for isomers such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), tocopherols and carotenoids. Separation of cis-trans geometric isomers such as diethylstilbestrol and polar compounds such as monosubstituted benzenes and anilines can also be achieved. These two columns offer more flexible selectivity and higher separation performance than commercial C 18 and phenyl columns. There is a difference in molecular shape selectivity between the two stationary phases for the same analyte test probes. SiO 2 @PAE-ANT showed slightly better linear selectivity for non-polar shape-restricted isomers compared to SiO 2 @PAE-PA with Janus-type PAE-PA bonding phase. This separation behavior may be attributed to the ordered spatial structure formed by the gel factor on the surface of the stationary phase and the combined effect of multiple weak interaction centers (hydrophobic, hydrophilic, hydrogen bonding and π-π interactions). It was also possible to separate nucleoside and nucleobase strongly polar compounds well in the HILIC mode, suggesting that hydrophilic groups in PAE-ANT and PAE-PA are involved in the interactions, reflecting their amphiphilic nature. The results show that the ordered gelation of dendritic organic small molecule gelators on the SiO 2 surface, along with multiple carbonyl-π, π-π and other interactions, play a crucial role in the separating shape-restricted isomers. The integrated and ordered functional groups serve as the primary driving force behind the exceptionally high molecular shape selectivity of SiO 2 @PAE-ANT and SiO 2 @PAE-PA phases. Alterations in the structure of dendritic organic small molecule gelators can impact both molecular orientation and recognition ability, while changes in the type of functional groups influences the separation mechanism of shape-restricted isomers. [ABSTRACT FROM AUTHOR]

• A strategy to improve host cell protein clearance in the downstream process for therapeutic proteins using multimodal chromatography. • High throughput process development workflow used to screen resins at the polishing step and multimodal chromatography resin Nuvia cPrime identified as a promising candidate. • Host cell proteins eluted at a lower salt concentration than the therapeutic protein over multimodal chromatography when operated in bind/elute mode. • An intermediate low salt wash step on Nuvia cPrime enabled clearance of 80 % of host cell proteins including some known to be problematic and difficult-to-remove. In biotherapeutic protein production, host cell proteins (HCPs) are one of the main process related impurities which must be cleared and controlled through downstream processing. In this paper, we studied a novel therapeutic protein molecule which had a high level of HCP co-purification throughout the downstream process. Here, we focused on the polishing purification step and developed an effective strategy for improving HCP clearance using multimodal chromatography (MMC) resin, Nuvia cPrime. A high throughput process development (HTPD) workflow was used to identify the resin and process conditions which could enable significant HCP clearance while maintaining acceptable product quality and process performance. HCP analysis of gradient elution fractions on multimodal chromatography found that HCPs eluted at the beginning of the gradient, at a lower salt concentration than the therapeutic protein. Based on these findings, a step elution process involving an intermediate low salt wash was developed to clear weak-binding HCPs, while retaining the therapeutic protein on the column. This strategy was highly effective and enabled 80 % reduction in total HCP content, including some problematic and difficult to remove candidates such as Peroxiredoxin-1, Serine protease HTRA1, Clusterin and Lipoprotein lipase. [ABSTRACT FROM AUTHOR]

• A high throughput parallel batch screen with plate detection has been developed. • Sequential salt steps are used to get the first moment of elution in the gradients. • Large sets of resins, proteins and pH conditions are evaluated. • Batch retention and separability data sets are consistent with column results. • Using plate detection enables rapid chromatography gradient screens. This paper employs a high-throughput parallel batch (microtiter plate) adsorption screen with sequential salt step increases to rapidly generate protein elution profiles for multiple resins at different pHs using a protein library. The chromatographic set used in this work includes single mode, multimodal anion-exchange (MMA), and multimodal cation-exchange (MMC) resins. The protein library consists of proteins with isoelectric points ranging from 5.1 to 11.4 with varying hydrophobicities as determined by their retention on hydrophobic interaction chromatography. The batch sequential experiments are carried out using one protein at a time with a wide set of resins at multiple pH conditions, thus enabling simple microtiter plate detection. A mathematical formulation is then used to determine the first moment of the distributions from each chromatogram (sequential step elution) generated in the parallel batch experiments. Batch data first moments (expressed in salt concentration) are then compared to results obtained from column linear salt gradient elution, and the techniques are shown to be consistent. In addition, first moment data are used to calculate one-resin separability scores, which are a measure of a resin's ability, at a specified pH, to separate the entire set of proteins in the library from one another. Again, the results from the batch and column experiments are shown to be comparable. The first moment data sets were then employed to calculate the two-resin separability scores, which are a measure of the ability of two resins to synergistically separate the entire set of proteins in the library. Importantly, these results based on the two-resin separability performances derived from the batch and column experiments were again shown to be consistent. This approach for rapidly screening large numbers of chromatographic resins and mobile phase conditions for their elution behavior may prove useful for enabling the rapid discovery of new chromatographic ligands and resins. [ABSTRACT FROM AUTHOR]