Journal of Chromatography B (v.903, #C)

Ophthalmate detection in human plasma with LC–MS–MS by Simon A.W.G. Dello; Hans M.H. van Eijk; Evelien P.J.G. Neis; Mechteld C. de Jong; Steven W.M. Olde Damink; Cornelis H.C. Dejong (1-6).
► The developed LC–MS/MS assay allowed measurement of low OPH levels in human plasma. ► Plasma should be deproteinized immediately to generate accurate OPH data. ► Relatively high levels of OPH were measured in human liver biopsies.Based on animal experimentations, ophthalmate (OPH) has recently been suggested as a potential plasma biomarker to probe hepatic GSH homeostasis. Up until now, the inability to accurately determine OPH concentrations in human plasma prohibited further studies of OPH metabolism in humans. This study therefore aimed to study the influence of delayed sample preparation on OPH concentrations using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Venous plasma samples from 5 healthy human volunteers were incubated for varying times (5, 30, 60 and 120 min) at temperatures of 4 °C and 37 °C to investigate potential enzymatic degradation. At 37 °C, the decrease in OPH reached significance after 120 min (74.6% (range: 56.2–100.0%; p  < 0.0001)). At 4 °C, the same trend was observed but did not reach significance. These findings indicate ongoing enzymatic activity, stressing the need for immediate sample deproteinization to obtain reliable plasma concentrations. To investigate the feasibility of the here developed method, baseline arterial plasma values of 21 patients scheduled for partial liver resection were determined to be 0.06 ± 0.03 μmol/l (mean ± s.d.). In addition, in pooled samples from 3 patients, an OPH calibration curve was spiked to arterial plasma, arterial whole blood and liver biopsy material, resulting in a linear calibration curve in all cases. Individual measurements of baseline samples revealed that both arterial whole blood and liver biopsy material contained significant levels of endogenous OPH, namely 16.1 (11.8–16.4) μmol/l and 80.0 (191.8–349.2) μmol/kg, respectively. In conclusion, the present LC–MS/MS assay enables the accurate measurement of OPH in human plasma, whole blood and liver biopsies. Freshly prepared samples and immediate deproteinization are mandatory to block enzymatic degradation.
Keywords: Hepatotoxicity; Ophthalmate; Glutathione; LC–MS/MS;

► We report a UPLC–MS/MS method for analysis of several B-vitamins simultaneously in human milk. ► Recovery rates were determined between 73 and 100%, accuracy between 96 and 102%. ► The sample preparation methods can greatly affect recovery rates. ► Analytes are quantifiable in amounts well below previously reported values.A novel, rapid and sensitive ultra-performance liquid-chromatography tandem mass spectrometry (UPLC–MS/MS) method for the simultaneous determination of several B-vitamins in human milk was developed. Resolution by retention time or multiple reaction monitoring (MRM) for thiamin, riboflavin, flavin adenine dinucleotide (FAD), nicotinamide and pyridoxal (PL) has been optimized within 2 min using a gradient of 10 mM ammonium formate (aq) and acetonitrile. Thiamin-(4-methyl-13C-thiazol-5-yl-13C3) hydrochloride, riboflavin-dioxo-pyrimidine-13C4,15N2, and pyridoxal-methyl-d3 hydrochloride were used as internal standards. A sample-like matrix was found to be mandatory for the external standard curve preparation. 13C3-caffeine was added for direct assessment of analyte recovery. Intra- and inter-assay variability for all analytes ranged from 0.4 to 7.9% and from 2.2 to 5.2%, respectively. Samples were subjected to protein precipitation and removal of non-polar constituents by diethyl ether prior to analysis. Quantification was done by ratio response to the stable isotope labeled internal standards. The standard addition method determined recovery rates for each vitamin (73.0–100.2%). The limit of quantitation for all vitamins was between 0.05 and 5 ppb depending on the vitamin. Alternative approaches for sample preparation such as protein removal by centrifugal filter units, acetonitrile or trichloroacetic acid revealed low recovery and a greater coefficient of variation. Matrix effect studies indicated a significant influence by matrix constituents, showing the importance of stable isotope labeled internal standards for analyte quantitation in complex matrices.
Keywords: B-vitamins; Human milk; Infant requirements; Lactation; UPLC–MS/MS;

Preparation, characterization, and process performance of composite fibrous adsorbents as cation exchangers for high throughput and high capacity bioseparations by Poondi Rajesh Gavara; Rosa Cabrera; Rami Reddy Vennapusa; Mariano Grasselli; Marcelo Fernandez-Lahore (14-22).
► We observed an internal functional hydrogel in a novel composite fiber. ► We found high dynamic binding capacity for lysozyme. ► High resolution was exhibited at high flow rates that can be used in purification. ► We demonstrated the superior performance during early protein capture.Fibrous materials are proposed as novel chromatographic supports depicting high throughput and high product capacity. In this work, a composite fiber harboring strong cation-exchange moieties has been investigated. Such materials were characterized by a plethora of physical methods including degree of swelling (DS), scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM), and Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR). The composite showed a high degree of grafting (∼30%) and exhibited a high swelling ratio (∼300%). Moreover, homogenous grafting and the development of an internal (functional) hydrogel were observed. The fibrous adsorbent was packed utilizing a designed “double roll” supported-structure and subsequently tested for packing efficiency and chromatography performance. The mentioned system showed similar packing efficiency of height equivalent to a theoretical plate (HETP) value and higher permeability coefficient (0.92 × 10−7  cm2) than commercial resins. Experimentally determined Peclet number (Pe) values were within the range 60–90, suggesting a close-to-plug-flow condition. Total ionic capacity of the fibrous adsorbent was determined by the transition pH method. A capacity of 6.5 mequiv./g was obtained. Moreover, a high dynamic binding capacity for lysozyme was found to be 283 mg/g. On the other hand, a bed of randomly packed fiber also demonstrated high-resolution ability when a mixture of model protein was utilized to that end. Resolution was maintained at high flow rates (up to 900 cm/h) and utilizing shorter gradient development routines. Direct sequestration of a model protein (lysozyme) was also possible from an artificial mixture containing 1.5% yeast homogenate. Summarizing, the composite fibrous adsorbents exhibited superior performance during early protein capture and intermediate-resolution applications.
Keywords: Composite fibrous adsorbent; Hydrogel; Column packing; Permeability coefficient; Dynamic binding capacity; Resolution factor;

► The structures of purine alkaloids and their metabolites were identified. ► An LC–IT-TOF-MS method was developed and validated for in vivo study. ► Two internal standards with different concentrations were used. ► The pharmacokinetic parameters were compared between different groups. ► The metabolism of caffeine in rats was illustrated.A liquid chromatography hybrid ion trap time-of-flight mass spectrometric (LC–IT-TOF-MS) method was developed and validated for identification and simultaneous determination of the potential bioactive components from green tea in rat plasma. The plasma samples were extracted by liquid–liquid extraction with ethyl acetate and separated on Shim-pack XR-ODS II column by a gradient elution within a runtime of 8.0 min. The mobile phase consisted of A (0.1% formic acid in acetonitrile) and B (0.1% formic acid in water) at a flow rate of 0.4 ml/min. Two prototype components and one metabolite were successfully identified as caffeine, theobromine and theophylline according to their retention times, accurate molecule weight, and major fragment ions. Then they were determined with the addition of two internal standards, hypoxanthine and paracetamol. The linear range was 10–10,000 ng/ml for caffeine, 2.0–2000 ng/ml for theobromine and 1.0–1000 ng/ml for theophylline, respectively. Intra-day and inter-day precision were within 6.0% and 10.9%, and accuracy was less than 4.8% and 6.5%, respectively. The validated method was successfully applied to investigate the dynamic change rules of caffeine, theobromine and theophylline in rat plasma after oral administration of caffeine, theobromine and green tea extract. The comparative analysis of the pharmacokinetic parameters indicated that there were obvious differences between green tea extract administration and single substances administration.
Keywords: Green tea; Identification; Metabolism; Caffeine; Pharmacokinetics; LC–IT-TOF-MS;

Combining multidimensional liquid chromatography and MALDI–TOF-MS for the fingerprint analysis of secreted peptides from the unexplored sea anemone species Phymanthus crucifer by Armando A. Rodríguez; Ludger Ständker; André J. Zaharenko; Anoland G. Garateix; Wolf-Georg Forssmann; Lászlo Béress; Olga Valdés; Yasnay Hernández; Abilio Laguna (30-39).
► Multidimensional approach that introduces pH gradient IEC into venom fingerprinting. ► We report the most abundant and unprecedented diversity of peptides in a sea anemone. ► First analysis of the peptide composition of the sea anemone Phymanthus crucifer. ► The use of a new buffer for pH gradient IEC.Sea anemones are sources of biologically active proteins and peptides. However, up to date few peptidomic studies of these organisms are known; therefore most species and their peptide diversity remain unexplored. Contrasting to previous venom peptidomic works on sea anemones and other venomous animals, in the present study we combined pH gradient ion-exchange chromatography with gel filtration and reversed-phase chromatography, allowing the separation of the 1–10 kDa polypeptides from the secretion of the unexplored sea anemone Phymanthus crucifer (Cnidaria/Phymanthidae). This multidimensional chromatographic approach followed by MALDI–TOF-MS detection generated a peptide fingerprint comprising 504 different molecular mass values from acidic and basic peptides, being the largest number estimated for a sea anemone exudate. The peptide population within the 2.0–3.5 kDa mass range showed the highest frequency whereas the main biomarkers comprised acidic and basic peptides with molecular masses within 2.5–6.9 kDa, in contrast to the homogeneous group of 4–5 kDa biomarkers found in sea anemones such as B. granulifera and B. cangicum (Cnidaria/Actiniidae). Our study shows that sea anemone peptide fingerprinting can be greatly improved by including pH gradient ion-exchange chromatography into the multidimensional separation approach, complemented by MALDI–TOF-MS detection. This strategy allowed us to find the most abundant and unprecedented diversity of secreted components from a sea anemone exudate, indicating that the search for novel biologically active peptides from these organisms has much greater potential than previously predicted.
Keywords: Sea anemone; Venom; Toxin; Peptidomics; pH gradient; Mass fingerprint; Multidimensional chromatography; Phymanthus crucifer;

► We develop LC/MS/MS method for simultaneous determination of three sesquiterpene lactones in rat plasma for the first time. ► Sensitivity, recovery and reproducibility of the developed method are good. ► There are few studies on pharmacokinetics of sesquiterpene lactones, which have shown good biological activities. Therefore, it is suggested that more attentions should be paid to the research on these compounds in vivo.A rapid and sensitive liquid chromatography–tandem mass spectrometry method has been developed and validated for the determination of 1-acetoxy-6α-hydroxyeriolanolide, 1β-hydroxyalantolactone and ivangustin from Herba Inula extract in rat plasma. Plasma samples were pretreated by protein precipitation with methanol. Chromatographic separation was accomplished on a TOSOH TSKgel ODS column with mobile phase consisting of methanol and 0.3% formic acid (80:20, v/v). The detection was carried out by multiple-reaction monitoring mode under positive electrospray ionization. The quantification was performed using the transitions of m/z 309.1/185.0 for 1-acetoxy-6α-hydroxyeriolanolide, m/z 249.0/231.1 for 1β-hydroxyalantolactone and ivangustin and m/z 285.0/193.0 for diazepam, respectively. Calibration curves were linear over the concentration range of 4–800 ng/mL for 1-acetoxy-6α-hydroxyeriolanolide, 8–500 ng/mL for 1β-hydroxyalantolactone and ivangustin. The limit of detection (LOD) was 1 ng/mL for 1-acetoxy-6α-hydroxyeriolanolide, 1.6 ng/mL for 1β-hydroxyalantolactone and ivangustin (S/N = 3). The intra-day and inter-day precisions (RSD%) for the three compounds were less than 7.8% and 8.6%, and the accuracy (RE%) ranged from −4.6 to 6.8%. The method was successfully applied to pharmacokinetic studies of the three sesquiterpene lactones after oral administration of 300 mg/kg Herba Inula extract to rats, the t 1/2 of 1-acetoxy-6α-hydroxyeriolanolide, 1β-hydroxyalantolactone and ivangustin was 9.65 ± 1.43, 14.88 ± 0.82 and 13.93 ± 2.74 (h). The AUC(0−t) of 1-acetoxy-6α-hydroxyeriolanolide, 1β-hydroxyalantolactone and ivangustin was 1102.46 ± 247.04, 808.92 ± 117.53 and 990.35 ± 275.49 (ng h/mL), respectively.
Keywords: LC/MS/MS; Sesquiterpene lactones; Herba Inula; Pharmacokinetics; Rat plasma;

► Simultaneous determination of blonanserin and its metabolite in human plasma and urine by LC–MS/MS was developed with short analysis time. ► Our analytical method is sensitive and the LLOQ of blonanserin and blonanserin C in plasma and urine are as very low as 0.01 ng/ml. ► Liquid–liquid extraction is developed which is simple in sample preparation and economical. ► A structural analogue is synthesized as IS. It has a consistent matrix effect to blonanserin and blonanserin C with high and stable recovery, thus the precision and accuracy are enhanced accordingly. ► It has been successfully applied to investigate the pharmacokinetics of blonanserin and blonanserin C in humans.Blonanserin is a novel atypical antipsychotic with highly selective receptor antagonist activity to dopamine D2 and 5-HT2A. N-desethyl blonanserin (blonanserin C) is its major active metabolite in human plasma. Herein we report a new highly sensitive, selective, and rapid liquid chromatography–tandem mass spectrometry method to determine blonanserin and blonanserin C simultaneously in human plasma and urine, with N-desethyl-chlor-blonanserin (blonanserin D) as internal standard (IS). Blonanserin and blonanserin C were extracted from aliquots of plasma and urine with ethyl acetate and dichloromethane (4:1) as the solvent and chromatographic separation was performed using an Agilent Eclipse Plus C18 column. The mobile phase was composed of: acetonitrile and ammonium formate–formic acid buffer containing 5 mM ammonium formate and 0.1% formic acid (87:13, v/v). To quantify blonanserin, blonanserin C, and blonanserin D, respectively, multiple reaction monitoring (MRM) transition of m/z 368.2 → 297.2, m/z 340.2 → 297.1, and m/z 356.2 → 313.3 was performed in positive mode. The analysis time was about 5.5 min. The calibration curve was linear in the concentration range of 0.01–2 ng/ml. The lower limit of quantification reached 0.01 ng/ml. The intra and inter-day precision and relative errors were less than 8.0% and 6.6% for three QC levels in plasma and urine. The current LC–MS/MS method was validated as simple, sensitive, and accurate and has been successfully applied to investigate the pharmacokinetics of blonanserin and blonanserin C in humans.
Keywords: Blonanserin; Metabolite; HPLC–MS/MS; Human plasma; Pharmacokinetics;

Miniaturised free flow isotachophoresis of bacteria using an injection moulded separation device by Jeff E. Prest; Sara J. Baldock; Peter R. Fielden; Nicholas J. Goddard; Royston Goodacre; Richard O’Connor; Bernard J. Treves Brown (53-59).
► A new design of injection moulded free flow electrophoresis separation device has been produced. ► The new design of device has been successfully used for free flow isotachophoresis separations. ► Bacteria samples were separated and fractionated using the device.A new design of miniaturised free flow electrophoresis device has been produced. The design contains a separation chamber that is 45 mm long by 31.7 mm wide with a depth of 50 μm and has nine inlet and nine outlet holes to allow for fraction collection. The devices were formed of polystyrene with carbon fibre loaded polystyrene drive electrodes and produced using injection moulding. This means that the devices are low cost and can potentially be mass produced. The devices were used for free flow isotachophoresis (FFITP), a technique that can be used for focussing and concentrating analytes contained within complex sample matrices. The operation of the devices was demonstrated by performing separations of dyes and bacterial samples. Analysis of the output from FFITP separations of samples containing the bacterium Erwinia herbicola, a biological pathogen, by cell culturing and counting showed that fractionation of the output was achieved.
Keywords: Free flow isotachophoresis; Free flow electrophoresis; Miniaturisation; Sample preparation; Bacteria;

► Fusion M13 phage with disulfide constrained heptapeptide, C-WSFFSNI-C, as ligand to capture HBcAg. ► EBA adsorbent immobilized with fusion M13 phage can capture HBcAg with high selectivity from unclarified feedstock. ► A modified EBAC operation with recirculation of feedstock into the expanded bed has improved the uptake rate of HBcAg. ► The antigenicity of HBcAg purified by this affinity EBAC still preserved.Fusion M13 phage with disulfide constrained heptapeptide, C-WSFFSNI-C, inserted into the minor coat protein (gpIII), has been selected in the current study as ligand in direct purification of hepatitis B core antigen (HBcAg) from unclarified Escherichia coli (E. coli) feedstock. The selected fusion phage showed strong association with the surface of the core particle. In the present study, this fusion M13 phage was immobilized onto Streamline base matrix via epoxy activation and used as adsorbent to capture HBcAg from crude E. coli homogenate. The maximum binding capacity for the adsorbent was 3.76 mg/mL with equilibrium coefficient of 1.83 mg/mL. Due to the slow uptake rate of HBcAg by M13 phage-immobilized adsorbents, a modified EBAC operation with recirculation of feedstock into the expanded bed has been investigated in this study. The introduction of feedstock recirculation has led to an 18% increase in yield; however, the purity of the eluted product was reduced by 15% compared with typical EBAC operation. The level of antigenicity exhibited by the core particles purified by both EBAC operations employed in the present study was comparable to that purified using sucrose ultracentrifugation.
Keywords: M13 phage; Affinity purification; EBAC; HBcAg;

► A quantitative method for three flavonoids C-glycosides of Abrus mollis extract in vivo. ► Three similar compounds were simultaneously determined with simple sample disposal. ► Application for routine pharmacokinetic and tissue distribution studies.A simple HPLC–ESI-MS method was developed for the determination of vicenin-2 (1), isoschaftoside (2), and schaftoside (3) of Abrus mollis extract in mice plasma and tissues (heart, liver, spleen, lungs, and kidneys). The separation was achieved by HPLC on a Shim-Pack CLC-ODS column with a mobile phase composed of 0.1% formic acid (mobile phase A, 72%) and methanol–isopropanol (9:1) (mobile phase B, 28%). The electrospray source of the MS was operated in the selective ion monitoring (SIM) mode at m/z 593 ([M−H]) for 1, and 563 ([M−H]) for 2 and 3, respectively. The limit of detection (LOD) of 13 was in the range of 8.5–12.6 ng/mL for plasma, and 32.5–49.4 ng/g for tissue tested. The limit of quantification (LOQ) was found to be 25 ng/mL for plasma, and 100 ng/g for tissue. The calibration curves were linear in all matrices (r 2  > 0.994) in the concentration range of 25–500 ng/mL in plasma or 100–1250 ng/g in tissue, respectively. Intra-day and inter-day precision studies demonstrate that the method is precise with coefficients of variation intra-day and inter-day below 5.9 and 7.4% for all the samples, respectively. The recoveries of three flavonoid C-glycosides ranged from 95.3 to 106.4% for plasma, and 92.6 to 107.3% for tissues. Following oral administration of A. mollis extract to mice at a dose of 72 mg/kg, the concentrations of 13 in plasma and tissues were quantifiable in bio-samples collected up to 180 min. The method described is suitable for studies on the distribution of three flavonoid C-glycosides of A. mollis extract in plasma and different tissues of mice.
Keywords: HPLC–ESI-MS; Abrus mollis; Vicenin-2; Isoschaftoside; Schaftoside; Bio-distribution;

► Chinensinaphthol methyl ether (CME) is a potential pharmacologically active ingredient isolated from the dried plants of Justicia procumbens L. (Acanthaceae). ► A sensitive and specific LC–MS/MS method was developed and validated for the analysis of CME in rat plasma using buspirone as the internal standard (IS). ► The assay was shown to be linear over the range of 0.50–500 ng/mL, with a lower limit of quantification of 0.50 ng/mL. ► The assay has been successfully used for pharmacokinetic evaluation of CME after intravenous and oral administration of 1.80 mg/kg CME in rats. ► The oral absolute bioavailability (F) of CME was estimated to be 3.2 ± 0.2% with an elimination half-life (t 1/2) value of 2.4 ± 0.8 h, suggesting its poor absorption and/or strong metabolism in vivo.Chinensinaphthol methyl ether (CME) is a potential pharmacologically active ingredient isolated from the dried plants of Justicia procumbens L. (Acanthaceae). A sensitive and specific LC–MS/MS method was developed and validated for the analysis of CME in rat plasma using buspirone as the internal standard (IS). The analyte was extracted with ethyl acetate and chromatographed on a reverse-phase Agilent Zorbax-C18 110 Å column (50 mm × 2.1 mm, 3.5 μm). Elution was achieved with a gradient mobile phase consisting of water and acetonitrile both containing 0.1% formic acid at a flow rate of 0.40 mL/min. The analytes were monitored by tandem–mass spectrometry with positive electrospray ionization. The precursor/product transitions (m/z) in the positive ion mode were 394.5 → 346.0 and 386.1 → 122.0 for CME and IS, respectively. The assay was shown to be linear over the range of 0.50–500 ng/mL, with a lower limit of quantification of 0.50 ng/mL. The method was shown to be reproducible and reliable with the inter- and intra-day accuracy and precision were within ±15%. The assay has been successfully used for pharmacokinetic evaluation of CME after intravenous and oral administration of 1.80 mg/kg CME in rats. The oral absolute bioavailability (F) of CME was estimated to be 3.2 ± 0.2% with an elimination half-life (t 1/2) value of 2.4 ± 0.8 h, suggesting its poor absorption and/or strong metabolism in vivo.
Keywords: Justicia procumbens; Chinensinaphthol methyl ether; Bioavailability; LC–MS/MS; Rat;

► 10-Methoxycamptothecin (MCPT) shows very high cytotoxicity against 2774 cell lines. ► 10-Hydroxycamptothecin (HCPT) was identified as a metabolite of MCPT in rat plasma. ► A RP-HPLC method was developed for simultaneous analysis of MCPT and HCPT. ► MCPT may mainly metabolize to HCPT in rats plasma after i.v. administration.Both 10-methoxycamptothecin (MCPT) and 10-hydroxycamptothecin (HCPT) are the natural bioactive derivatives of camptothecin (CPT) isolated from Camptotheca acuminata, and have been confirmed to possess high anti-cancer properties. In the present study, HCPT was identified as the major metabolite of MCPT in rat plasma through HPLC/photodiode array detection (PDA) and LC–MS/MS analysis. A sensitive and reliable RP-HPLC method with fluorescence detection was developed and validated for the simultaneous analysis of MCPT and HCPT in rat plasma. The parental CPT was used as an internal standard (IS). A piecewise linear function was used over lower and higher concentrations, respectively. The calibration curves were linear (r 2  > 0.999) over concentrations from 1.25 to 20 ng/mL and 20 to 320 ng/mL for both MCPT and HCPT. The method had an accuracy of 92.24–113.90%, and the intra- and inter-day precision (RSD%) were 10.05% or less for MCPT and HCPT. The stability data showed no significant degradation occurred under the experimental conditions. The mean recoveries at concentrations of 2.5, 40 and 160 ng/mL were 95.09 ± 3.94%, 98.67 ± 1.40% and 95.65 ± 2.15% for MCPT and 84.06 ± 4.39%, 84.85 ± 3.10% and 81.03 ± 4.44% for HCPT, respectively. The lower limit of quantification (LLOQ) using 0.1 mL of plasma was 1.25 ng/mL for both MCPT and HCPT. This method was successfully applied to the pharmacokinetic study of MCPT and its metabolite HCPT in rat plasma after intravenous administration.
Keywords: 10-Methoxycamptothecin; 10-Hydroxycamptothecin; Demethylation; Metabolite identification; Quantification;

Application of solid phase microextraction on dental composite resin analysis by Ven-Shing Wang; Ta-Yuan Chang; Chien-Chen Lai; San-Yue Chen; Long-Chen Huang; Keh-Ping Chao (88-94).
► DI-SPME coupled with LC-UV was developed for the analysis of TEGDMA, UDMA and Bis-GMA in saliva. ► This simple method showed above 10-fold greater sensitivity than the direct injection method. ► The DI-SPME method achieved good accuracy and precision for both intra- and inter-day assays. ► A mass transfer model was developed to describe the sorption kinetic of analyte for DI-SPME.A direct immersion solid phase microextraction (DI-SPME) method was developed for the analysis of dentin monomers in saliva. Dentine monomers, such as triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA) and 2,2-bis-[4-(2-hydroxy-3-methacryloyloxypropoxy) phenyl]-propane (Bis-GMA), have a high molecular weight and a low vapor pressure. The polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber with a medium polarity was employed for DI-SPME, and 215 nm of detection wavelength was found to be optimum in the chromatogram of HPLC measurement. The calibration range for DI-SPME was 0.30–300 μg/mL with correlation coefficients (r) greater than 0.998 for each analyte. The DI-SPME method achieved good accuracy (recovery 96.1–101.2%) and precision (2.30–8.15% CV) for both intra- and inter-day assays of quality control samples for three target compounds. Method validation was performed on standards dissolved in blank saliva, and there was no significant difference (p  > 0.2) between the DI-SPME method and the liquid injection method. However, the detection limit of DI-SPME was as low as 0.03, 0.27 and 0.06 μg/mL for TEGDMA, UDMA and Bis-GMA, respectively. Real sample analyses were performed on commercial dentin products after curing for the leaching measurement. In summary, DI-SPME is a more sensitive method that requires less sample pretreatment procedures to measure the resin materials leached in saliva.
Keywords: SPME; PDMS/DVB; HPLC; Dentin monomer; Saliva;

Determination of 22 synthetic cannabinoids in human hair by liquid chromatography–tandem mass spectrometry by Melanie Hutter; Stefan Kneisel; Volker Auwärter; Merja A. Neukamm (95-101).
► A LC–MS/MS method for the quantification of synthetic cannabinoids in human hair was developed. ► The method is accurate, precise, selective and specific with good linearity and a lower limit of quantification of 0.5 pg/mg. ► In authentic hair samples from chronic consumers two to six synthetic cannabinoids were present simultaneously. ► The highest measured concentration was approximately 1100 pg/mg JWH-081.Herbal mixtures of the “Spice“-type contain a variety of synthetic cannabinoids. To prove the contact of a person with synthetic cannabinoids in a previous period of up to several months, hair testing is ideally suited. A rapid, simple and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) assay was developed to determine 22 synthetic cannabinoids in human hair. The synthetic cannabinoids JWH-007, JWH-015, JWH-018, JWH-019, JWH-020, JWH-073, JWH-081, JWH-122, JWH-200, JWH-203, JWH-210, JWH-250, JWH-251, JWH-398, AM-694, AM–2201, methanandamide, RCS-4, RCS-4 ortho isomer, RCS-8, WIN 48,098 and WIN 55,212-2 were extracted from 50 mg hair by 3-h ultrasonification in ethanol. The extracts were analysed on a triple-quadrupole linear ion trap mass-spectrometer in scheduled multiple reaction monitoring mode (sMRM). The method was fully validated and proved to be accurate, precise, selective and specific with satisfactory linearity within the calibrated range and a lower limit of quantification of 0.5 pg/mg for 20 compounds. Authentic hair samples from chronic consumers showed the presence of two to six synthetic cannabinoids in the same segment. In the first segment, concentrations of up to 78 pg/mg JWH-081 were present. In segmented hair, the concentrations of most substances increased from the first (proximal) to the third segment. The highest concentration was ca. 1100 pg/mg JWH-081. The results of segmental hair analysis in chronic users suggest incorporation of the drugs in head hair via side-stream smoke condensation as a major route. In summary, the method can be used to prove the contact with herbal mixtures containing synthetic cannabinoids and thus contributes to an efficient abstinence control.
Keywords: Spice; Hair analysis; LC–MS/MS; Cannabimimetic; Herbal mixtures;

► Bioanalysis of oxyntomodulin with 2D-LC–MS/MS using RPLC ion pair chromatography. ► Linear range of 1–1000 ng/mL method validation. ► Showed utility of method with intravenously dosed rat samples.Polypeptide therapeutics present a challenge for quantitative analysis when using immunoassays or recently, liquid chromatography–tandem mass spectrometry because of their structural similarities to endogenous proteins and peptides in plasma. In this assay, a Waters Oasis® mixed-mode anion exchange (MAX) microelution modified solid phase extraction (SPE) method coupled with two-dimensional reversed phase ion pair chromatography–tandem mass spectrometry was used for the validation and analysis of oxyntomodulin in rat plasma. Oxyntomodulin (OXM) and its isotope labeled internal standard were extracted from rat plasma and analyzed with a chromatographic run time of 8 min. Modified SPE, two-dimensional liquid chromatography coupled with 3-nitrobenzyl alcohol as a mobile phase additive, and monitoring of multiply charged SRM transitions (+7 charge state) of OXM were necessary to achieve a lower limit of quantification of 1 ng/mL. The method was validated with a linear range of 1–1000 ng/mL, with average R 2 of 0.992, and reversed calculated residuals between −8.6% and 6.0%. Precision and accuracy for inter- and intra-day were determined to be ±17%. Following a complete validation, the method was applied to show utility using rat plasma samples that were intravenously dosed with oxyntomodulin.
Keywords: Two-dimensional liquid chromatography; Polypeptide; LC–MS/MS; Plasma; Ion pair; Multiply charged;

► Anti-lysozyme DNA aptamer affinity chromatography column was prepared for HPLC. ► DNA aptamers were covalently immobilized on the surface of monolithic column. ► Lysozyme was extracted in a single step by the aptamer monolithic column.A DNA aptamer based high-performance affinity chromatography is developed for selective extraction and screening of a basic protein lysozyme. First, a poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolithic column was synthesized in situ by thermally initiated radical polymerization, and then an anti-lysozyme DNA aptamer was covalently immobilized on the surface of the monolith through a 16-atom spacer arm. The target protein lysozyme but non-target proteins can be trapped by the immobilized anti-lysozyme DNA aptamer. In contrast, lysozyme cannot be trapped by the immobilized oligodeoxynucleotide that does not contain the sequence of the anti-lysozyme DNA aptamer. The study clearly demonstrates the trapping of lysozyme by the immobilized anti-lysozyme DNA aptamer is mainly due to specific recognition rather than simple electrostatic interaction of positively charged protein and the negatively charged DNA. The inter-day precision was determined as 0.8% for migration time and 4.2% for peak area, respectively. By the use of aptamer affinity monolith, a screening strategy is developed to selectively extract lysozyme from chicken egg white, showing the advantages of high efficiency, low cost and ease-of-operation.
Keywords: Aptamer; Affinity chromatography; Lysozyme; HPLC;

► Simple, sensitive and rapid LC–MS/MS method has been developed and validated. ► The method was applied for tissue distribution study. ► Recovery of both compounds were above 81% in all tissue and plasma. ► The assay demonstrated a high degree of suitable precision and accuracy. ► Protein precipitation was applied in an assay using LC–MS/MS.Endoplasmic reticulum (ER) stress is associated with various human diseases. Phenylbutyric acid (PBA) is a well-known chemical chaperone that regulates ER stress. The main objective of this study was to develop a simple, rapid, and sensitive method for the simultaneous determination of phenylbutyric acid and its metabolite, phenylacetic acid (PAA). A LC–MS/MS analysis using negative electrospray ionization was used. Samples were analyzed by multiple reaction monitoring (MRM) in 15 min of total run time, using d11-PBA and d7-PAA as internal standards. The limit of quantification was 1 μg/g for tissue and 0.8 μg/mL for plasma. Recoveries for plasma and tissues were higher than 81% for both PBA and PAA. The inter-day and intra-day accuracy and precision were within ±15%. We then further successfully validated this method by applying it to determine the tissue distribution of PBA and its metabolite PAA after i.p. injection of PBA at a dose of 500 mg/kg in mice. The maximum concentrations of PBA and PAA in plasma and tissues were seen at 15 min and 45 min, respectively. The PBA plasma concentration was 15-fold higher than the concentration in the kidney, whereas the PAA plasma concentration was 6-fold higher than the concentration in the liver. The area under the curve decreased in the order of plasma > kidney > liver > heart > muscle > lung for PBA and plasma > liver > kidney > heart > muscle > lung for PAA. The tissue to plasma ratio ranged from 0.007 to 0.063 for PBA and 0.016 to 0.109 for PAA. In summary, the LC–ESI-MS method developed in this study is simple, sensitive and reliable.
Keywords: Phenylbutyric acid; Phenylacetic acid; Tissue distribution; Pharmacokinetic; Mass spectrometry;

High-throughput assay for simultaneous quantification of the plasma concentrations of morphine, fentanyl, midazolam and their major metabolites using automated SPE coupled to LC–MS/MS by Sussan Ghassabian; Seyed Mojtaba Moosavi; Yarmarly Guerra Valero; Kiran Shekar; John F. Fraser; Maree T. Smith (126-133).
► An on-line robotic SPE was used to extract eight analytes from plasma. ► Basic analytes were extracted using a basic loading and an acidic elution. ► Only 11.5 min is required for extraction and quantification of each sample. ► Using a sensitive detector, the LLOQ of <3.5 ng/mL were achieved for all analytes. ► The method was validated and applied successfully in a clinical study.A rapid LC–MS/MS assay method for simultaneous quantification of morphine, fentanyl, midazolam and their major metabolites: morphine-3-β-d-glucuronide (M3G), morphine-6-β-d-glucuronide (M6G), norfentanyl, 1′-hydroxymidazolam (1-OH-MDZ) and 4-hydroxymidazolam (4-OH-MDZ) in samples of human plasma has been developed and validated. Robotic on-line solid phase extraction (SPE) instrumentation was used to elute the eight analytes of interest from polymeric SPE cartridges to which had been added aliquots (150 μL) of human plasma and aliquots (150 μL) of a mixture of two internal standards, viz. morphine-d3 (200 ng/mL) and 1′-hydroxymidazolam-d5 (50 ng/mL) in 50 mM ammonium acetate buffer (pH 9.25). Cartridges were washed using 10% methanol in ammonium acetate buffer, pH 9.25 (1 mL, 2 mL/min) before elution with mobile phase comprising 0.1% formic acid in water (A) and acetonitrile (B) with a flow rate of 0.6 mL/min using an 11.5 min run time. The analytes were separated on a C18 X-Terra® analytical column. The linear concentration ranges were 0.5–100 ng/mL for fentanyl, norfentanyl and midazolam; 1–200 ng/mL for 4-hydroxymidazolam, 2.5–500 ng/mL for 1′-hydroxymidazolam and 3.5–700 ng/mL for morphine, M3G, and M6G. The method showed acceptable within-run and between-run precision (relative standard deviation (RSD) and accuracy <20%) for quality control (QC) samples spiked at concentrations of 80% and 50% of the ULOQ, 3 times higher than the LLOQ, and also at the LLOQ. Furthermore, analytes were stable in samples (after mixing with internal standard) for at least 48 h in the autosampler (except for 4-hydroxymidazolam which decreased by 22% after 24 h), 5 h at room temperature and after three cycles of freeze and thaw. No autosampler carry-over was observed and the absolute recovery (the area ratio of analyte in plasma relative to that in ammonium acetate buffer 50 mM, pH 9.25) was in the range 40% (midazolam) to 110% (morphine). The assay was applied successfully to the measurement of the analytes of interest in plasma samples from patients on extracorporeal membrane oxygenation (ECMO).
Keywords: Morphine; M3G, M6G; Fentanyl; Norfentanyl; Midazolam (MDZ), 1-OHMDZ; 4-OHMDZ; On-line SPE; LC–MS/MS;

► Development of an LC–MS/MS-method for the determination of pyridoxal-5′-phosphate in whole blood. ► The method is characterized by short run times and simple sample preparation. ► Validated showed precision CV < 5%, mean recovery of 98%, no significant matrix effects and an LLOQ of 4 nmol/l. ► The method showed an excellent correlation with an existing HPLC method.Vitamin B6 is a cofactor in numerous biologic processes that include gluconeogenesis, neurotransmitter synthesis and amino acid metabolism. The aim of this study was to develop a method to measure the concentration of the biologically active form of vitamin B6 (pyridoxal-5′-phosphate, PLP) in whole blood with stable isotope dilution LC–ESI-MS/MS and compare this new procedure with an established HPLC method based on derivatization of pyridoxal-5′-phosphate. 50 μl of stable isotope (PLP-d3) was added to 250 μl of sample, followed by deproteinization with 10% trichloroacetic acid. After centrifugation, 20 μl of the supernatant was injected into the LC–ESI-MS/MS. Reversed phase chromatography was performed on a UPLC system, using a Waters™ Symmetry C18 column, with a gradient of 0.1% formic acid in methanol. PLP was measured on a tandem MS with a mass transition of 247.8 > 149.8 in the positive ion mode with a collision energy of 14 eV. The chromatographic run lasted 4 min. The method was linear from 4 to 8000 nmol/l. The intra-day and inter-day precision ranged between 1.7–2.8% and 3.0–4.1%, respectively. The mean absolute matrix-effect was 99.3% [97–102%]. The relative matrix-effect was 98.8%. The mean recovery was 98% [89–103%]. The lower limit of quantification was 4 nmol/l. The comparison of the LC–ESI-MS/MS method with our current HPLC method yielded the following equation: LC–ESI-MS/MS = 1.11 [confidence interval, CI: 1.03–1.20] × HPLC + 4.6 [CI: −1.3 to 11.0] (r 2  = 0.94). This LC–ESI-MS/MS based method is characterized by simple sample processing and a short run time. The comparison with the current HPLC method is excellent although a significant proportional bias was detected. To conclude, the LC–ESI-MS/MS method is an appropriate method to determine PLP in whole blood.
Keywords: Method validation; Vitamin B6; Pyridoxal-5′-phosphate; LC–ESI-MS/MS; Whole blood;

► We developed a rapid second-tier test for acylcarnitines and amino acids. ► We evaluated response factors and matrix effects not previously report in NBS. ► Fast chromatographic separation of acylcarnitines and amino acids in 3.1 min. ► Our method allows for differential diagnosis of MSUD and other disorders. ► We provide chromatographic separation of C4 and C5 isomers.We have developed a high resolution liquid chromatographic separation with electrospray ionization (ESI) mass spectrometry detection for the combined analysis of twelve acylcarnitines and seven amino acids commonly measured in newborn screening heritable metabolic disorders. Samples were prepared by punching 3.2 mm disks out of dried blood spots and extracting with a mixture of methanol and 0.1% formic acid containing stable isotopically labeled internal standards. Analysis was performed on an UHPLC system using a HILIC amide, 2.1 mm × 50 mm, 1.7 μm column. A normal phase gradient, employing 10 mM ammonium acetate in 90:10 acetonitrile/water for mobile phase B and 0.1% formic acid in water for mobile phase A, was used. Optimized multiple reaction monitoring (MRM) was used for detection of amino acids and acylcarnitines on a Waters Premier mass spectrometer. Quantification of analytes was performed using internal calibration by fortification of sodium heparin whole blood with analytes at appropriate levels to encompass the range around the reported cut-off values. The method was fully validated with respect to precision, accuracy, recovery, linearity, matrix suppression and extraction robustness. Precision and accuracy were evaluated over 3 days and determined to be acceptable with an overall precision within 10% and accuracy within 15% of theoretical for all analytes except for acetylcarnitne at one fortified level, which quantitated 21.8% lower than the expected value. This method is suitable as a second-tier test for newborn screening of specific disorders associated with abnormal levels of acylcarnitines and amino acids, potentially reducing false positive cases and shortening the time to diagnosis.
Keywords: Newborn screening; Second-tier test; Acylcarnitines; Amino acids UHPLC;

► Therapeutic drug monitoring is beneficial whilst using tyrosine kinase inhibitors. ► Dried blood spot (DBS) is a simple and less invasive blood sampling technique. ► High throughput method for DBS analysis was developed using LC–MS/MS. ► The method proved to be accurate and precise in a wide concentration range. ► A good correlation between drug levels measured in plasma and in DBS was observed.Imatinib, dasatinib and nilotinib are three tyrosine kinase inhibitors currently used to treat Bcr-Abl1 positive chronic myelogenous leukaemia (CML). However, achieving maximum benefit with these drugs may require optimal dosing and adherence to therapy. In those cases, therapeutic drug monitoring (TDM) can be a useful tool in managing patients with CML. The paper presents simple and high throughput method for simultaneous determination of all three TKIs in dried blood spot (DBS) samples from CML patients. DBS samples were prepared by applying 10 μL of spiked whole blood onto an Agilent DBS cards. Whole blood spot was punched out of the card, transferred to a well in a 96-well Captiva ND Lipids filter plate. After the addition of isotopically labelled internal standard, the drug was extracted with 0.1% formic acid in methanol. The collected extract (1 μL) was injected onto a Phenomenex Kinetex 50 mm × 2.1 mm C18 column and eluted with acetonitrile gradient into a triple quadrupole ESI–MS/MS Agilent 6460 operated in positive mode. The total run time was only 2.6 min. The method was validated in terms of linearity, selectivity, specificity, accuracy, precision, absolute and relative matrix effect and stability. The effect of haematocrit (Hct) on the accurate concentration determination was also examined. The method was linear in the range of 50–5000 μg/L for imatinib and nilotinib and in the range of 2.5–250 μg/L for dasatinib, with correlation coefficient values higher than 0.997. Lower limits of quantification (LLOQ) were 50 μg/L for imatinib and nilotinib and 2.5 μg/L for dasatinib. The method proved to be accurate (% bias < 13.2) and precise (CV < 10.3%) on intra- as well as on inter-day basis. Sample matrix (% ME = 94.5–106.7) and different Hct values had no significant effect on the accuracy of measured concentrations. Samples proved to be stable whilst stored on DBS cards at room temperature or in the refrigerator; however, at 40 °C the stability of dasatinib was compromised. The method presented was successfully applied to clinical samples.
Keywords: Imatinib; Dasatinib; Nilotinib; DBS; LC–MS/MS;

Purification and differential biological effects of ginger-derived substances on normal and tumor cell lines by James Almada da Silva; Amanda Blanque Becceneri; Hêmily Sanches Mutti; Ana Carolina Baptista Moreno Martin; Maria Fátima das Graças Fernandes da Silva; João Batista Fernandes; Paulo Cezar Vieira; Márcia Regina Cominetti (157-162).
► We describe an optimization of [6]-, [8]- and [10]-gingerol purification. ► We demonstrate their specific anti-proliferative activities against tumor cells. ► [6]-, [8]- and [10]-gingerol can be used as models for anticancer drug design.This study describes an optimization of [6]-, [8]- and [10]-gingerol isolation and purification in semi-preparative HPLC scale and their anti-proliferative activity. The gingerols purification was carried out in HPLC system using a Luna-C18 and the best mobile phase evaluated was MeOH/H2O (75:25, v/v). This new methodology for the gingerols isolation was very effective, since considerable amounts (in the range of milligrams) with a good purity degree (∼98%) were achieved in 30 min of chromatographic run. [6]-, [8]- and [10]-Gingerol purified by this methodology inhibited the proliferation of MDA-MB-231 tumor cell line with IC50 of 666.2 ± 134.6 μM, 135.6 ± 22.6 μM and 12.1 ± 0.3 μM, respectively. These substances also inhibited human fibroblasts (HF) cell proliferation, however in concentrations starting from 500 μM. In conclusion, our results demonstrate an optimization of gingerols isolation and their specific anti-proliferative activities against tumor cells, suggesting their use as important models for drug design in an attempt to develop new compounds with fewer side effects when compared to conventional chemotherapy.
Keywords: Zingiber officinale; HPLC; Gingerols; Ginger; Cell proliferation; Cancer; MDA-MB-231;

Fishing human monoclonal antibodies from a CHO cell supernatant with boronic acid magnetic particles by L. Borlido; A.M. Azevedo; A.G. Sousa; P.H. Oliveira; A.C.A. Roque; M.R. Aires-Barros (163-170).
► Boronic acid and Protein A functionalized magnetic particles were studied. ► A human monoclonal antibody was selectively purified from a CHO supernatant. ► The performance of boronic acid particles was mainly affected by the adsorption pH. ► The particles were successfully re-used in a multi-cycle operation.In this work we have evaluated the potential of boronic acid functionalized magnetic particles for the one-step capture of a human monoclonal antibody (mAb) from a Chinese hamster ovary (CHO) cell culture supernatant. For comparison, Protein A coated magnetic particles were also used. The most important factor influencing the overall process yield and product purity in boronic acid particles was found to be the binding pH. Basic pH values promoted higher purities while resulting in decreased yields due to the competing effects of molecules such as glucose and lactate present in the cell culture supernatant. After optimization, the particles were successfully used in a multi-cycle purification process of the mAb from the CHO feedstock. Boronic acid particles were able to achieve an average overall yield of 86% with 88% removal of CHO host cell proteins (HCP) when the binding was performed at pH 7.4, while at pH 8.5 these values were 58% and 97%, respectively. In both cases, genomic DNA removal was in excess of 97%. Comparatively, Protein A particles recorded an average overall yield of 80% and an HCP removal greater than 99%. The adsorption of the mAb to the boronic acid particles was shown to be mediated by strong affinity interactions. Overall, boronic acid based purification processes can offer a cost-effective alternative to Protein A as the direct capturing step from the mammalian cell culture.
Keywords: Magnetic particles; Boronic acid; Monoclonal antibody; Affinity purification; Downstream processing;

Quantitative profiling of glucosinolates by LC–MS analysis reveals several cultivars of cabbage and kale as promising sources of sulforaphane by Katsunori Sasaki; Makiko Neyazaki; Kazutoshi Shindo; Toshiya Ogawa; Masaki Momose (171-176).
► We upgraded the LC–MS system with a reversed-phase C30 column for glucosinolates. ► This method is a suitable tool for profiling glucosinolates contained in Cole crops. ► The solid phase extraction tool (96-well plate) speeded up preparation time. ► We searched widely among cabbage and kale varieties for high glucoraphanin content. ► GR contents of 3 cabbage and 6 kale cultivars compared with the highest broccoli.Sulforaphane is an isothiocyanate well known for its potential health benefits. With the aim of finding sulforaphane supply sources, its precursor, glucoraphanin, was widely searched for among Brassica oleracea varieties. Quantitative profiling of seven glucosinolates by LC–MS analysis was performed on 6 cultivars of broccoli, 32 of cabbage and 24 cultivars of kale. The glucoraphanin levels found in three cultivars of cabbage and six cultivars of kale were comparable with, or even higher than, the highest of broccoli (119.4 mg/100 g FW). The most promising group belonged to the black kale, Cavolo nero. Use of a C30 column and an ammonium formate buffer in LC–MS and a micro plate solid phase extraction technique was highly effective.
Keywords: Glucosinolate; Glucoraphanin; Sulforaphane; Broccoli, Cabbage; Kale; Brassica oleracea; Cole; LC–ESI-MS;

High-performance liquid chromatography/tandem mass spectrometry for simultaneous determination of four dicaffeoylquinic acids in rat plasma by Yongbing Sun; Lan Xu; Qi Wang; Shuangfeng He; Hesong Huang; Wugang Zhang; Gang Li; Yulin Feng; Xiaojian Luo (177-181).
► Four dicaffeoylquinic acids were the major components of Ainsliaea fragrans cham. ► A C18 column (150 mm × 2.1 mm, 1.8 μm) was applied to separate the four analytes. ► A specific HPLC–MS/MS method was developed to support the pharmacokinetics study.A specific and reliable HPLC–MS/MS method was developed and validated for the simultaneous determination of four dicaffeoylquinic acids (DCQA): 3,4-DCQA, 1,5-DCQA, 3,5-DCQA and 4,5-DCQA. The analytes were separated on a C18 column (150 mm × 2.1 mm, 1.8 μm) and a triple-quadrupole mass spectrometry equipped with an electrospray ionization (ESI) source was applied for detection. The plasma sample was prepared by a liquid–liquid extraction method and the recovery for the four analytes was around 80%. The calibration curves were linear over a concentration range of 10.6–1060.0 ng/mL for 3,4-DCQA, 19.2–1920.0 ng/mL for 1,5-DCQA, 14.0–2900.0 ng/mL for 3,5-DCQA, 9.7–970.0 ng/mL for 4,5-DCQA. The intra-day and inter-day precision was less than 15% and the relative error (RE) were all within ±15%. The validated method was successfully applied to a pharmacokinetics study in rats after oral administration of the extracts of Ainsliaea fragrans cham (a traditional Chinese herb).
Keywords: HPLC–MS/MS; Dicaffeoylquinic acid; Pharmacokinetics; Rat plasma;