A poly(vinyl alcohol)–cationic cellulose (PVA–CC) copolymer encapsulated SiO2 stationary phase (PVA–CC–Sil) for hydrophilic interaction liquid chromatography (HILIC) is described. It is prepared simply by combining SiO2 with a preformed PVA–CC solution, then filtering and curing thermally, finally generating a thin PVA–CC copolymer coating onto SiO2. The preparation is easy to implement and no organic solvent is involved in. The phase shows obvious positive electrostatic character and typical HILIC character, exhibiting different selectivity relative to twelve commercial HILIC phases. Good running stability and a wide pH tolerance range (at least 10) are observed for PVA–CC–Sil. Excellent separation efficiency is obtained for model analytes (e.g. plate counts are ∼114 000 plates per m and ∼150 000 plates per m for ribose and 4-hydroxybenzoic acid, respectively). Good separation performance for saccharides of low or high degrees of polymerization by PVA–CC–Sil is also observed.

•The first fully pH-stable, quaternary ammonium functionalized HILIC stationary phase.•It offers excellent hydrophilic and positively charged characters.•The phase exhibits much lower bleeding and wider pH tolerance range.High chemical inertness of porous graphitic carbon particles (PGC) makes their surface modification rather difficult. Here a facile way is proposed to prepare a PGC stationary phase with quaternary ammonium-polyvinyl alcohol mixed functional groups for hydrophilic interaction liquid chromatography (HILIC) by generating a thin layer of polyvinyl alcohol (PVA) and poly(diallyldimethylammonium chloride) (DDAC) copolymer onto PGC particles. The phase shows obvious positively electrostatic character and typical HILIC character, exhibiting different selectivity relative to several HILIC phases and bare PGC. To the best of our knowledge, this is the first fully pH-stable, quaternary ammonium functionalized HILIC phase. It is much superior to silica-based HILIC phases in terms of wide pH tolerance (2.1–12.7) and low bleeding.A fully pH-stable, positively charged HILIC phase is firstly described by generating a thin coating of polyvinyl alcohol (PVA) and poly(diallyldimethylammonium chloride) (DDAC) copolymer onto porous graphic carbon.

We report a poly(vinyl alcohol) (PVA)-coated porous graphitic carbon (PGC, Hypercarb) packing as a novel stationary phase for hydrophilic interaction liquid chromatography (HILIC). The exterior and the pores of the PGC particles are coated with a thin layer of PVA by soaking the particles in a PVA solution, filtering, and thermally cross-linking the PVA. Such PVA coated PGC particles (5.7 μm diameter), hereinafter called PVA–PGC are stable at least through pH 1.0–12.7, can be made in <2 h, and exhibit different selectivity relative to six commercial HILIC phases and bare PGC. To our knowledge, this is the first fully pH-stable, completely neutral HILIC phase. Excellent efficiency stable is observed for polar analytes (∼70 000 and 118 000 plates/m for cytosine and resorcinol, respectively). Retention closely resembles standard HILIC behavior. Other substances can also be easily incorporated in the PVA layer; an anion exchange column can be readily made by incorporating diallyldimethylammonium chloride in the PVA coating solution. The ease of preparation without the requirement of synthetic skills or paraphernalia and the possibility of incorporating a variety of modifiers makes this a particularly versatile approach.

•An integrated device combining charge detector and electrodialytic suppressor together.•The integration device shows comparable performance with separate counterpart.•The integration device simplifies the structure configuration of IC system.An integrated device of electrodialytic membrane suppressor and charge detector (CHD) for ion chromatography (IC) is described, aiming to simplify system complexity and reduce possible extra-column dispersion as well. The device is a flow-through design consisting of five chambers isolated by ion exchange membranes and ionic screens. Two independent electric sources are used to respectively supply CHD and suppressor sections of the device, and a common electrode serves both the cathode of CHD and the anode of suppressor simultaneously. The integrated device has similar performance as a separate suppressor or a CHD while its dead volume and dispersion are reduced ∼18% and ∼37% compared with the combination of a CHD and a suppressor. To our knowledge, this is the first description of such an integrated device with dual functionalities of suppression and CHD.An integrated device of electrodialytic membrane suppressor and charge detector for ion chromatography (IC) is described. The device can simultaneously serve as suppression and detection and its performance is comparable to separate counterparts.

•A high pressure electrodialytic K2CO3 eluent generator is described.•A KHCO3 pH modifier is fabricated to online modify the pH of eluent.•K2CO3 eluent generator produces the eluent linearly with the current.An electrodialytic potassium carbonate eluent generator and its associated potassium bicarbonate eluent generator have been fabricated for ion chromatography (IC). The device can withstand high backpressure up to ∼32 MPa and no observable leakage under such pressure is found during 2 h. In the range of 0–13.7 mM, potassium carbonate concentration can be generated linearly with the applied current with a slope that is essentially Faradaic. At least 10 mM potassium carbonate can be online changed into 10 mM potassium bicarbonate via a potassium bicarbonate eluent generator, which offers an easy way to manipulate the separation selectivity. When coupled with IC system, the device demonstrated good reproducibility indicated by less than 0.52% of the relative standard deviation of the retention times.An electrodialytic potassium carbonate generator for ion chromatography has been fabricated and evaluated. It generates eluent at near-Faradaic efficiency and bears backpressure up to ∼32 MPa.

•A facile way to prepare decarboxylic-functionalized weak cation exchanger.•Simultaneous separation achieved for alkali, alkaline earth and transition metals.•It can be extended as an easy way to prepare other kinds of WCX.A novel weak cation exchanger (WCX) with dicarboxyl groups functionalized has been developed by clicking mercaptosuccinic acid onto silica gel. The simple synthesis starts with modification of silica gel with triethoxyvinylsilane, followed by efficient coupling vinyl-bonded silica with mercaptosuccinic acid via a “thiol-ene” click reaction. The obtained WCX demonstrated good separation and high selectivity towards common metals. Simultaneous separation of 10 alkali, alkaline earth and transition metals was achieved within 12 min. Ion exchange and complex mechanism dominates the separation process. Its utility was demonstrated for determination of metals in tap water.A facile and green way is proposed to prepare dicarboxyl-functionalized weak cation exchanger via a “thio-ene” click reaction. It demonstrated good ability for simultaneous separation of metals.Figure optionsDownload full-size imageDownload as PowerPoint slide

Multiple layers of polyvinyl alcohol (PVA) coating are generated onto silica gel by thermal immobilization to form a stationary phase applied for hydrophilic interaction liquid chromatography (HILIC). It offers an easy way to manipulate the thickness of PVA coating and the obtained stationary phase demonstrated high efficiency and high chemical stability.

An arginine-functionalized stationary phase for hydrophilic interaction liquid chromatography (HILIC) has been prepared for the first time by clicking arginine onto silica gel. It offers an efficient separation of organic acids, nucleotides and sugars. More interestingly, it exhibited excellent selectivity and enrichment toward acidic glycopeptides, even at a ratio of 1:150 to non-glycopeptides.

•Graphene nanoplatelet was first used as an SPE sorbent for phthalate ester.•The sorbent demonstrated better performance relative to commons sorbents.•Graphene nanoplatelet sorbent can be recyclable.Graphene nanoplatelet (GN) as a solid-phase extraction (SPE) sorbent in combination with high performance liquid chromatography has been used for the determination of five phthalate esters (PAEs) in aqueous solution. The operation parameters affecting the extraction efficiency were optimized. Comparative studies showed that GN was superior to other common SPE sorbents in terms of recovery and adsorption capacity. Under optimization conditions, detection limits of 0.09–0.33 ng mL−1 were achieved for five PAEs and enrichment factors of 402–711 for the analytes were obtained. The proposed method was successfully applied for the determination of PAEs in tap water and drink samples with recoveries ranging from 87.7% to 100.9%.Graphene nanoplatelet was proved to be a highly efficient SPE sorbent for determination of phthalate esters in aqueous solution.

•Synthesis of MIP sorbents via streptomycin template was proposed.•MIP demonstrated high specific recognition for aminoglycosides antibiotics (AAs).•MIP has applied for the determination of AAs in honey sample.Aminoglycoside antibiotic (AA)-selective molecularly imprinted polymer (MIP) sorbent was synthesized by polymerization of methacrylic acid and ethylene glycol dimethacrylate in the presence of streptomycin as template molecule. The MIP sorbent was in detail characterized and its performance was evaluated by selecting four model AAs including streptomycin, gentamicin, spectinomycin and dihydrostreptomycin. Relative to non-imprinted polymer (NIP), the MIPs exhibited much higher recognizable capacity and specificity to the AAs and negligible adsorption for non-AAs as well. In combination of hydrophilic interaction liquid chromatography–tandem mass spectrometry (HILIC–MS/MS), the MIP sorbent-based solid phase extraction (SPE) was able to effectively determine the residue of four model AAs in honey samples with recovery ranging from 90% to 110%. The limit of detection (and the limit of quantitation) of streptomycin, gentamicin, spectinomycin and dihydrostreptomycin was 4.5 (15.0), 2.4 (8.0), 6.0 (20.0) and 1.8 (6.0) μg/kg, respectively. Relative standard deviations of intraday and inter-day assay under three spiked levels were 4.4–12.0% and 6.8–14.6%, respectively.

•An easy way for preparing amide stationary phase for HILIC was presented.•The amide stationary phase demonstrated good HILIC performance.•Good separation of inorganic anions was achieved on the column.A novel amide stationary phase (ASP) for hydrophilic interaction liquid chromatography (HILIC) has been prepared via the Click chemistry method. It was based on the strategy that the amino group of Asparagine was easily transferred to the corresponding azido group and then clicked onto terminal alkyne-silica gel in the presence of Cu(I)-based catalyst. For the tested polar compounds including nucleosides and nucleic acid bases, ASP-based column has demonstrated good performance in terms of separation efficiency and column stability, and the retention mechanism was found to match well the typical HILIC retention. In addition, the ASP described here showed much better selectivity in separation of inorganic anions under ion chromatography mode relative to other kinds of commercial ASP.

•Novel aspartic acid HILIC materials were developed via click chemistry method.•Click AA showed higher selectivity and coverage than commercial materials.•A uniform method for glycopeptide enrichment was developed via Click AA.A novel hydrophilic interaction chromatography (HILIC) material was developed via clicking aspartic acid onto silica gel (termed as Click AA). The material demonstrated highly hydrophilic property and was used as solid phase extraction sorbent for selective enrichment of glycopeptides. By optimization of extraction conditions, Click AA exhibited high selectivity to glycopeptides with various peptide length and different types of glycans, which was much superior to similar commercial products. The application of Click AA to simulated proteomic samples further proved its specialty toward glycopeptides.

A simple way was proposed to prepare reverse phase open tubular column (OTC) for capillary electrochromatography (CEC) by dynamically coating cationic latex particles with C10 functional groups onto the fused silica capillary with surface sulphonation. The latex particles are bounded into the capillary wall via electrostatic attraction force and demonstrate good stability under test conditions. Relative bare silica capillary, reverse electroosmotic flow (EOF) is generated for the OTC due to the existence of cationic latex particles onto the capillary. Preliminary separation of aromatic compounds on an OTC with 50 i.d. has been demonstrated.Highlights► A simple way to prepare reverse phase open tubular electrochromatography column was presented. ► Cationic nanoparticles with dual function groups of C10/quaternary ammonium were synthesized. ► Good separation of aromatic compounds by open tubular column has been demonstrated.

A silica based amino stationary phase was prepared by immobilization of propargylamine on azide-silica via click chemistry. This readily prepared click amino stationary phase demonstrated good selectivity in separation of common inorganic anions under ion chromatography (IC) mode, and the triazole ring in combination with free amino group was observed to play a major role for separation of the anions examined. On the other hand, the stationary phase also showed good hydrophilic interaction liquid chromatography (HILIC) properties in the separation of polar compounds including nucleosides, organic acids and bases. The retention mechanism was found to match well the typical HILIC retention.

An anion open tubular column (OTC) by coating cationic latex particle onto the silica capillary with surface sulfonate functionalized has been prepared and evaluated. The performance of the OTC was observed to be superior to that of those prepared by the bare silica capillary without sulfonation in term of separation efficiency. To increase the surface area of the capillary, acid and base-based etching method for treating silica capillary wall was carried out and compared. An OTC with multiple layers was prepared by alternatively coating cationic and anionic latex particles aiming to further increase the column capacity. The anion OTC with size of 50 μm i.d.×1 m long demonstrated good separation of common inorganic anions with high efficiency (e.g. for NO2−, its theory plate number is 11655 plate/m).Highlights► A simple way for preparing anion exchange open tubular column was presented. ► Acid and base etching methods were quantitatively compared. ► The open tubular column demonstrated good separation of inorganic anions.

A novel cascade electro-osmotic pump (EOP) has been fabricated by alternately connecting a cation monolithic column and anion monolithic column in series. In this manner, the change of electric polarity between each stage of the cascade EOP is easily achieved and the pressure output of the EOP could be greatly enhanced without increase of the applied voltage.

Ion chromatography (IC) is one of the most powerful analysis technologies for the determination of charged compounds. A novel click lysine stationary phase was prepared viaCu(I) catalyzed alkyne-azide 1,3-dipolar cycloaddition (CuAAC) and applied to the analysis of inorganic ions. The chromatographic evaluation demonstrated good performance (e.g. the plate number of thiocyanate is ∼50000 plates m−1) and effective separation ability for the common inorganic anions with aqueous Na2SO4 eluent. The separation mechanism was observed to be mainly dominated by ion exchange interaction. The retention of these analytes is highly dependent on the pH value of eluent. Compared with the lysine stationary phase prepared via the conventional manner, the click lysine exchanger demonstrated shorter retention time and better ion separation characteristics under the same chromatographic conditions, which is a great advantage for rapid separation and analysis of inorganic ions.

A novel silica-based strong anion exchanger was developed for ion chromatography by copolymerizing methyltrichlorosilane and 3-chloropropyltrichlorosilane. The method allows the column capacity to be easy control simply by adjusting the ratio of silanes. The unwanted residual silanol groups onto the surface of silica gel could also be greatly reduced by this strategy. The effective column capacity of the column used was measured to be 50.8 μequiv/column (2.03 μequiv/cm). The exchanger was characterized by solid state CP/MAS 13C NMR and elemental analysis and its separation performance was evaluated for the separation of common inorganic anions. The results showed that the column had good separation efficiency (e.g. the plate number of nitrite is 80,000/m) and the separation mechanism was observed to be dominantly governed by ion exchange mechanism. The utility of the column was demonstrated for the determination of nitrite and nitrate in saliva sample.