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Analytica Chimica Acta (v.742, #)

Editorial Board (pp. iii).

Preface by Hian Kee Lee Guest Editor (pp. 1-1).

Study of kinetic desorption rate constant in fish muscle and agarose gel model using solid phase microextraction coupled with liquid chromatography with tandem mass spectrometry by Oluranti Paul Togunde; Ken Oakes; Mark Servos; Janusz Pawliszyn (pp. 2-9).

Display Omitted► We model gel matrix to mimic fish tissue based on kinetic of diffusion of drugs. ► In vitro and in vivo time constant of the selected drugs was compared in fish tissue. ► SPME is demonstrated as a simple investigative tool in vivo system. ► Increasing gel concentration affects desorption rate of pharmaceuticals.This study aims to use solid phase microextraction (SPME), a simple tool to investigate diffusion rate (time) constant of selected pharmaceuticals in gel and fish muscle by comparing desorption rate of diffusion of the drugs in both agarose gel prepared with phosphate-buffered saline (PBS; pH 7.4) and fish muscle. The gel concentration (agarose gel model) that could be used to simulate tissue matrix (fish muscle) for free diffusion of drugs under in vitro and in vivo conditions was determined to model mass transfer phenomena between fibre polymer coating and environmental matrix such that partition coefficients and desorption time constant (diffusion coefficient) can be determined. SPME procedure involves preloading the extraction phase (fibre) with the standards from spiked PBS for 1h via direct extraction. Subsequently, the preloaded fibre is introduced to the sample such fish or agarose gel for specified time ranging from 0.5 to 60h. Then, fibre is removed at specified time and desorbed in 100μL of desorption solution (acetonitrile: water 1:1) for 90min under agitation speed of 1000rpm. The samples extract were immediately injected to the instrument and analysed using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS). The limit of detection of the method in gel and fish muscle was 0.01–0.07ngmL⁻¹ and 0.07–0.34ngg⁻¹, respectively, while the limit quantification was 0.10–0.20ngmL⁻¹ in gel samples and 0.40–0.97ngg⁻¹ in fish sample. The reproducibility of the method was good (5–15% RSD). The results suggest that kinetics of desorption of the compounds in fish tissue and different viscosity of gel can be determined using desorption time constant. In this study, desorption time constant which is directly related to desorption rate (diffusion kinetics) of selected drugs from the fibre to the gel matrix is faster as the viscosity of the gel matrix reduces from 2% (w/v) to 0.8% (w/v). As the concentration of gel reduces, viscosity of the gel will be reduced therefore allowing faster diffusion which invariably affect desorption time constant. Also, desorption time constant of model drugs in the fish muscle and 0.8–0.9% (w/v) gel model are similar based on free diffusion of studied compounds. In addition, in vitro and in vivo desorption time constant comparison shows that desorption time constant in an in vivo system (live fish muscle) is generally higher than an in vitro system (dead fish muscle) except for sertraline and nordiazepam. This study demonstrates SPME as a simple investigative tool to understand kinetics of desorption in an in vivo system with a goal to measure desorption rate of pharmaceuticals in fish.

Keywords: Pharmaceutical; Rate constant; Agar gel; SPME; Fish tissue; Muscle; In vitro; In vivo; Kinetic studies; Drug

Kinetic aspects of hollow fiber liquid-phase microextraction and electromembrane extraction by Astrid Gjelstad; Henrik Jensen; Knut Einar Rasmussen; Stig Pedersen-Bjergaard (pp. 10-16).

Display Omitted► A comparison of the extraction kinetics of HF-LPME and EME was performed. ► In HF-LPME, the mass transfer across the membrane was the rate limiting step. ► In EME, mass transfer across the SLM was much more rapid due to electrokinetic migration. ► Different pH conditions in the sample were investigated for HF-LPME and EME. ► Both techniques may be used in an extended pH range as compared to earlier recommendations.In this paper, extraction kinetics was investigated experimentally and theoretically in hollow fiber liquid-phase microextraction (HF-LPME) and electromembrane extraction (EME) with the basic drugs droperidol, haloperidol, nortriptyline, clomipramine, and clemastine as model analytes. In HF-LPME, the analytes were extracted by passive diffusion from an alkaline sample, through a (organic) supported liquid membrane (SLM) and into an acidic acceptor solution. In EME, the analytes were extracted by electrokinetic migration from an acidic sample, through the SLM, and into an acidic acceptor solution by application of an electrical potential across the SLM. In both HF-LPME and EME, the sample (donor solution) was found to be rapidly depleted for analyte. In HF-LPME, the mass transfer across the SLM was slow, and this was found to be the rate limiting step of HF-LPME. This finding is in contrast to earlier discussions in the literature suggesting that mass transfer across the boundary layer at the donor–SLM interface is the rate limiting step of HF-LPME. In EME, mass transfer across the SLM was much more rapid due to electrokinetic migration. Nevertheless, mass transfer across the SLM was rate limiting even in EME. Theoretical models were developed to describe the kinetics in HF-LPME, in agreement with the experimental findings. In HF-LPME, the extraction efficiency was found to be maintained even if pH in the donor solution was lowered from 10 to 7–8, which was below the pK_a-value for several of the analytes. Similarly, in EME, the extraction efficiency was found to be maintained even if pH in the donor solution increased from 4 to 11, which was above the pK_a-value for several of the analytes. The two latter experiments suggested that both techniques may be used to effectively extract analytes from samples in a broader pH range as compared to the pH range recommended in the literature.

Keywords: Hollow fiber liquid-phase microextraction; Electromembrane extraction; Supported liquid membrane; Extraction kinetics; Basic drugs

In situ solid-phase microextraction and post on-fiber derivatization combined with gas chromatography–mass spectrometry for determination of phenol in occupational air by Ali Es-haghi; Masoud Baghernejad; Habib Bagheri (pp. 17-21).

Display Omitted► SPME was applied to the sampling and extraction of phenol from occupational air. ► The feasibility of sol–gel based fibers for on-site sampling has been demonstrated. ► SPME probe can be simply taken into the clean areas of sterile preparation. ► The entry of unnecessary equipment and personnel into the clean area is avoided.A method based on solid-phase microextraction (SPME) followed by on-fiber derivatization and gas chromatography–mass spectrometry detection (GC–MS) for determination of phenol in air was developed. Three different types of SPME fibers, polar and non-polar poly(dimethylsiloxane) (PDMS) and polyethylene glycol (PEG) were synthesized using sol–gel technology and their feasibility to the sampling of phenol were investigated. Different derivatization reagents for post on-fiber derivatization of phenol were studied. Important parameters influencing the extraction and derivatization process such as type of fiber coating, type and volume of derivatizing reagent, derivatization time and temperature, extraction time, and desorption conditions were investigated and optimized. The developed method is rapid, simple, easy and inexpensive and offers high sensitivity and reproducibility. Under the optimized conditions, the detection limit of the method was 5ngL⁻¹ using selected ion monitoring (SIM) mode. The inter-day and intra-day precisions of the developed method under optimized conditions were below 10%, and the method shows linearity in the range of 20ngL⁻¹ to 500μgL⁻¹with the correlation coefficient of >0.99. The optimized method was applied to the sampling of phenol from some biologics production areas. The compared results obtained using current and standard methods were shown to be satisfactory.

Keywords: Phenol; Solid-phase microextraction; Sol–gel; Gas chromatography–mass spectrometry; Air sampling; Occupational air

Evaluation of a completely automated cold fiber device using compounds with varying volatility and polarity by Ruifen Jiang; Eduardo Carasek; Sanja Risticevic; Erasmus Cudjoe; Jamie Warren; Janusz Pawliszyn (pp. 22-29).

Display Omitted► We accomplished full automation by coupling the miniaturized cold fiber extraction device to commercial autosampler. ► The use of the septumless head injector improved robustness and precision ► The device provides improved extraction efficiencies for both aqueous and solid complex matrix samples.A fully automated cold fiber solid phase microextraction device has been developed by coupling to a GERSTEL multipurpose (MPS 2) autosampler and applied to the analysis of volatiles and semi-volatiles in aqueous and solid matrices. The proposed device was thoroughly evaluated for its extraction performance, robustness, reproducibility and reliability by gas chromatograph/mass spectrometer (GC/MS). With the use of a septumless head injector, the entire automated setup was capable of analyzing over 200 samples without any GC injector leakages. Evaluation of the automated cold fiber device was carried out using a group of compounds characterized by different volatilities and polarities. Extraction efficiency as well as analytical figures of merit was compared to commercial solid phase microextraction fibers. The automated cold fiber device showed significantly improved extraction efficiency compared to the commercial polydimethylsiloxane (PDMS) and cold fiber without cooling for the analysis of aqueous standard samples due to the low temperature of the coating. Comparing results obtained from cold fiber and commercial divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber temperature profile demonstrated that the temperature gap between the sample matrix and the coating improved the distribution coefficient and therefore the extraction amount. The linear dynamic range of the cold fiber device was 0.5ngmL⁻¹ to 100ngmL⁻¹ with a linear regression coefficient ≥0.9963 for all compounds. The limit of detection for all analytes ranged from 1.0ngmL⁻¹ to 9.4ngmL⁻¹. The newly automated cold fiber device presents a platform for headspace analysis of volatiles and semi-volatiles for large number of samples with improved throughput and sensitivity.

Keywords: Sample preparation; Solid-phase microextraction (SPME); Automated cold fiber device; Solid sample preparation; GC/MS

Vacuum-assisted headspace solid phase microextraction: Improved extraction of semivolatiles by non-equilibrium headspace sampling under reduced pressure conditions by Elefteria Psillakis; Evangelia Yiantzi; Lucia Sanchez-Prado; Nicolas Kalogerakis (pp. 30-36).

Display Omitted► Pressure dependence of HSSPME under non equilibrium sampling conditions. ► Faster extraction rates for HSSPME under vacuum conditions. ► Higher sensitivity within short sampling times and under mild conditions. ► Proposed procedure enables sampling of all compounds amenable to HSSPME.A new headspace solid-phase microextraction (HSSPME) procedure carried out under vacuum conditions is proposed here where sample volumes commonly used in HSSPME (9mL) were introduced into pre-evacuated commercially available large sampling chambers (1000mL) prior to HSSPME sampling. The proposed procedure ensured reproducible conditions for HSSPME and excluded the possibility of analyte losses. A theoretical model was formulated demonstrating for the first time the pressure dependence of HSSPME sampling procedure under non equilibrium conditions. Although reduced pressure conditions during HSSPME sampling are not expected to increase the amount of analytes extracted at equilibrium, they greatly increase extraction rates compared to HSSPME under atmospheric pressure due to the enhancement of evaporation rates in the presence of an air-evacuated headspace. The effect is larger for semivolatiles whose evaporation rates are controlled by mass transfer resistance in the thin gas film adjacent to the sample/headspace interface. Parameters that affect HSSPME extraction were investigated under both vacuum and atmospheric conditions and the experimental data obtained were used to discuss and verify the theory. The use of an excessively large headspace volume was also considered. The applicability of Vac-HSSPME was assessed using chlorophenols as model compounds yielding linearities better than 0.9915 and detection limits in the low-ppt level. The repeatability was found to vary from 3.1 to 8.6%.

Keywords: Sample preparation; HSSPME; Evaporation rates; Reduced pressure sampling; Non-equilibrium sampling

Semi-automated in vivo solid-phase microextraction sampling and the diffusion-based interface calibration model to determine the pharmacokinetics of methoxyfenoterol and fenoterol in rats by Joanne Chung Yan Yeung; Inés de Lannoy; Brad Gien; Dajana Vuckovic; Yingbo Yang; Barbara Bojko; Janusz Pawliszyn (pp. 37-44).

Display Omitted► In vivo SPME was used for PK studies of fenoterol and methoxyfenoterol in rats. ► New diffusion-based calibration interface model was used for calibration. ► Automated sampling system was used for in vivo studies. ► This is the first time in vivo SPME was successfully used for studies of hydrophilic drugs. In vivo solid-phase microextraction (SPME) can be used to sample the circulating blood of animals without the need to withdraw a representative blood sample. In this study, in vivo SPME in combination with liquid–chromatography tandem mass spectrometry (LC–MS/MS) was used to determine the pharmacokinetics of two drug analytes, R,R-fenoterol and R,R-methoxyfenoterol, administered as 5mgkg⁻¹ i.v. bolus doses to groups of 5 rats. This research illustrates, for the first time, the feasibility of the diffusion-based calibration interface model for in vivo SPME studies. To provide a constant sampling rate as required for the diffusion-based interface model, partial automation of the SPME sampling of the analytes from the circulating blood was accomplished using an automated blood sampling system. The use of the blood sampling system allowed automation of all SPME sampling steps in vivo, except for the insertion and removal of the SPME probe from the sampling interface. The results from in vivo SPME were compared to the conventional method based on blood withdrawal and sample clean up by plasma protein precipitation. Both whole blood and plasma concentrations were determined by the conventional method. The concentrations of methoxyfenoterol and fenoterol obtained by SPME generally concur with the whole blood concentrations determined by the conventional method indicating the utility of the proposed method. The proposed diffusion-based interface model has several advantages over other kinetic calibration models for in vivo SPME sampling including (i) it does not require the addition of a standard into the sample matrix during in vivo studies, (ii) it is simple and rapid and eliminates the need to pre-load appropriate standard onto the SPME extraction phase and (iii) the calibration constant for SPME can be calculated based on the diffusion coefficient, extraction time, fiber length and radius, and size of the boundary layer. In the current study, the experimental calibration constants of 338.9±30mm⁻³ and 298.5±25mm⁻³ are in excellent agreement with the theoretical calibration constants of 307.9mm⁻³ and 316.0mm⁻³ for fenoterol and methoxyfenoterol respectively.

Keywords: In vivo; solid-phase microextraction; Pharmacokinetics studies; Diffusion-based calibration; Automation; Fenoterol; Methoxyfenoterol

Role of precursors and coating polymers in sol–gel chemistry toward enhanced selectivity and efficiency in solid phase microextraction by Habib Bagheri; Hamed Piri-Moghadam; Tayebeh Ahdi (pp. 45-53).

Display Omitted► On-line sol–gel capillary microextraction was used for investigating the roles of precursors and coatings. ► Ten different sorbents intended to contain different precursors were prepared. ► The evaluation of the selectivity and efficiency of the prepared sorbents examined using different classes of compounds.To evaluate the selectivity and efficiency of solid phase microextraction (SPME) fiber coatings, synthesized by sol–gel technology, roles of precursors and coating polymers were extensively investigated. An on-line combination of capillary microextraction (CME) technique and high performance liquid chromatography (HPLC) was set up to perform the investigation. Ten different fiber coatings were synthesized in which five of them contained only the precursor and the rests were prepared using both the precursor and coating polymer. All the coatings were chemically bonded to the inner surface of copper tubes, intended to be used as the CME device and already functionalized by self-assembly monolayers of 3-(mercaptopropyl)trimethoxysilane (3MPTMOS). The selected precursors included tetramethoxysilane (TMOS), 3-(trimethoxysilyl)propylmethacrylate (TMSPMA), 3-(triethoxysilyl)-propylamine (TMSPA), 3MPTMOS, [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane (EPPTMOS) while poly(ethyleneglycol) (PEG) was chosen as the coating polymer. The effects of different precursors on the extraction efficiency and selectivity, was studied by selecting a list of compounds ranging from non-polar to polar ones, i.e. polycyclic aromatic hydrocarbon, herbicides, estrogens and triazines. The results from CME–HPLC analysis revealed that there is no significant difference between precursors, except TMOS, in which has the lowest extraction efficiency. Most of the selected precursors have rather similar interactions toward the selected analytes which include Van der Walls, dipole–dipole and hydrogen bond while TMOS has only dipole–dipole interaction and therefore the least efficiency. TMOS is silica but the other sorbents are organically modified silica (ORMOSIL). Our investigation revealed that it is rather impossible to prepare a selective coating using conventional sol–gel methodologies. The comparison study performed among the fiber coatings contained only a precursor and those synthesized by a precursor along with coating polymer proved that the extraction efficiency obtained for all coatings are the same. This is an indication that by selecting the appropriate precursor there is no need to use any coating polymer. In overall, a fiber coating in sol–gel process could be synthesize with no coating polymer which leads to faster, easier, cheaper and more controllable synthesis.

Keywords: Capillary microextraction; Sol–gel technology; Precursors; Coating polymer; High performance liquid chromatography

Preconcentration of aqueous dyes through phase-transfer liquid-phase microextraction with a room-temperature ionic liquid by Hsiu-Liang Chen; Shuo-Kai Chang; Chia-Ying Lee; Li-Lin Chuang; Guor-Tzo Wei (pp. 54-58).

.Display Omitted► We propose a new method of solvent microextraction. ► The new method utilizes the ion-pair behavior of ionic liquid in solvent extraction ► The new method can be employed for the extraction of charged species. ► High enrichment factors can be obtained from the proposed method.In this study, we employed the room-temperature ionic liquid [bmim][PF₆] as both ion-pair agent and an extractant in the phase-transfer liquid-phase microextraction (PTLPME) of aqueous dyes. In the PTLPME method, a dye solution was added to the extraction solution, comprising a small amount of [bmim][PF₆] in a relatively large amount of CH₂Cl₂, which serves as the disperser solvent to an extraction solution. Following extraction, CH₂Cl₂ was evaporated from the extractant, resulting in the extracted dyes being concentrated in a small volume of the ionic liquid phase to increase the enrichment factor. The enrichment factors of for the dye Methylene Blue, Neutral Red, and Methyl Red were approximately 500, 550 and 400, respectively; their detection limits were 0.014, 0.43, and 0.02μgL⁻¹, respectively, with relative standard deviations of 4.72%, 4.20%, and 6.10%, respectively.

Keywords: Room-temperature ionic liquid; Fluorescent dyes; Preconcentration; Phase-transfer liquid-phase microextraction

In-vial liquid–liquid microextraction-capillary electrophoresis method for the determination of phenolic acids in vegetable oils by Nur Bahiyah Abu Bakar; Ahmad Makahleh; Bahruddin Saad (pp. 59-66).

Display Omitted► In-vial LLME was developed for extraction of phenolic acids in vegetable oils.► After the extraction, phenolic acids were separated using CE.► The proposed method is “green” (minimum amounts of solvents) and rapid (less steps).An in-vial liquid–liquid microextraction method was developed for the selective extraction of the phenolic acids (caffeic, gallic, cinnamic, ferulic, chlorogenic, syringic, vanillic, benzoic, p-hydroxybenzoic, 2,4-dihydroxybenzoic, o-coumaric, m-coumaric and p-coumaric) in vegetable oil samples. The optimised extraction conditions for 20g sample were: volume of diluent ( n-hexane), 2mL; extractant, methanol: 5mM sodium hydroxide (60:40; v/v); volume of extractant, 300μL (twice); vortex, 1min; centrifugation, 5min. Recoveries for the studied phenolic acids were 80.1–119.5%. The simultaneous determination of the phenolic acid extracts was investigated by capillary electrophoresis (CE). Separations were carried out on a bare fused-silica capillary (50μm i.d.×40cm length) involving 25mM sodium tetraborate (pH 9.15) and 5% methanol as CE background electrolyte in the normal polarity mode, voltage of 30kV, temperature of 25°C, injection time of 4s (50mbar) and electropherograms were recorded at 200nm. The phenolic acids were successfully separated in less than 10min. The validated in-vial LLME-CE method was applied to the determination of phenolic acids in vegetable oil samples (extra virgin olive oil, virgin olive oil, pure olive oil, walnut oil and grapeseed oil). The developed method shows significant advantages over the current methods as lengthy evaporation step is not required.

Keywords: Phenolic acid; Capillary electrophoresis; In-vial liquid–liquid microextraction; Vegetable oil

Simultaneous determination of ultraviolet filters in aqueous samples by plunger-in-needle solid-phase microextraction with graphene-based sol–gel coating as sorbent coupled with gas chromatography–mass spectrometry by Hong Zhang; Hian Kee Lee (pp. 67-73).

Compared with commercial SPME fibers, the sol–gel graphene coating exhibited different selectivity for five UV filters with the log P values in the range of 3.18 and 5.95. Extraction conditions: each UV filter at 10μgL⁻¹ concentration in aqueous sample, pH=5, 40-min extraction time, room temperature, direct sampling 0% NaCI, 1000rpm, n=3.Display Omitted► Five UV filters are simultaneously determined by plunger-in-needle SPME-GC–MS. ► Novel sol–gel graphene is used as sorbent. ► OAD is employed to optimize extraction parameters.A simple, sensitive and selective method for the simultaneous determination of five ultraviolet (UV) filters: benzophenone, octyl salicylate, homosalate, 3-(4-methylbenzylidene) camphor, 2-hydroxy-4-methoxybenzophenone in aqueous samples was developed. The analytes were extracted by plunger-in-needle solid-phase microextraction with graphene as sorbent, then silylated on-fiber with N-methyl-N-(trimethylsilyl)trifluoroacetamide, and analyzed by gas chromatography–mass spectrometry. Factors affecting the performance of extraction and derivatization steps were thoroughly evaluated. For the optimization of extraction conditions, six relevant factors (parameters) were investigated, including sample pH, salt concentration, extraction time, extraction temperature, stirring speed and sampling mode. In the first stage, a two-level orthogonal array design OA₈ (2⁷) matrix was employed to study the effect of six factors. Based on the results of the first stage, three factors were selected for further optimization with a univariant approach during the second stage. Under the final optimized conditions, the method limits of detection for the five UV filters were determined to be in the range of 0.5 and 6.8ngL⁻¹ (at a signal/noise ratio of 3) and the precision (% relative standard deviation, n=5) was 0.8–5.6% at a concentration level of 1μgL⁻¹. The linearities for different analytes were 10–10,000 or 1–5000ngL⁻¹. The coefficients of determination for the calibration curves were all greater than 0.994. Finally, the proposed method was successfully applied to the extraction and determination of the UV filters in river water samples.

Keywords: Ultraviolet filters; Plunger-in-needle solid-phase microextraction; Graphene; Gas chromatography–mass spectrometry; Derivatization

Development and application of a new solid-phase microextraction fiber by sol–gel technology on titanium wire by Ali Es-haghi; Seyed Maryam Hosseini; Zahra Monsef Khoshhesab (pp. 74-79).

Display Omitted► Novel solid-phase microextraction fibers were prepared. ► Sol–gel technique was used for making fibers. ► Sol–gel was coated on the titanium wire substrate. ► The new fibers are robust, unbreakable with temperature and solvent stability. ► The fibers were used for extraction of BTEXs from aqueous samples.Novel solid-phase microextraction fibers were prepared based on sol–gel technique. Commonly used fused silica substrate was replaced by titanium wire which provided high strength and longer fiber life cycle. Titanium isopropoxide was employed as the precursor which provides a sol solution containing Ti–OH groups and shows more tendencies to the molecularly similar group on the substrate. Three different polymers, poly (dimethylsiloxane) (PDMS), poly(ethylenepropyleneglycol)-monobutyl ether (Ucon) and polyethylene glycol (PEG) were employed as coating polymer in preparing three different fibers. The applicability of these fibers was assessed for the headspace SPME (HS-SPME) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water sample followed by gas chromatography–mass spectrometry (GC–MS). Effects of different parameters such as fiber coating type, extraction condition, desorption condition were investigated and optimized. Under the optimized conditions, LODs and LOQs of 0.75–10μgL⁻¹ (S/N=3) and 1–20μgL⁻¹ (S/N=10) were respectively obtained. The method showed linearity in the range of 10–25,000μgL⁻¹ with correlation coefficient of >0.99. The relative standard deviation was less than 8%.

Keywords: BTEX; HS-SPME; GC–MS; Sol–gel technology; Titanium wire

Solid phase microextraction and LC–MS/MS for the determination of paliperidone after stereoselective fungal biotransformation of risperidone by Mariana Zuccherato Bocato; Rodrigo Almeida Simões; Leandro Augusto Calixto; Cristiane Masetto de Gaitani; Mônica Tallarico Pupo; Anderson Rodrigo Moraes de Oliveira (pp. 80-89).

Display Omitted► We developed a new LC–MS/MS method employing the polar organic mode to analyze risperidone and its chiral metabolites. ► We optimize a SPME procedure to extract these analytes from liquid culture medium. ► The method was validated and SPME showed to be a useful tool to be used in biotransformation studies. ► The biotransformation results showed that it is possible to obtain a drug in its enantiomeric pure form.The present work describes for the first time the use of SPME coupled to LC–MS/MS employing the polar organic mode in a stereoselective fungal biotransformation study to investigate the fungi ability to biotransform the drug risperidone into its chiral and active metabolite 9-hydroxyrisperidone (9-RispOH). The chromatographic separation was performed on a Chiralcel OJ-H column using methanol:ethanol (50:50, v/v) plus 0.2% triethylamine as the mobile phase at a flow rate of 0.8mLmin⁻¹. The SPME process was performed using a C18 fiber, 30min of extraction time and 5min of desorption time in the mobile phase. The method was completely validated and all parameters were in agreement with the literature recommendations. The Cunninghamella echinulata fungus was able to biotransform risperidone into the active metabolite, (+)-9-RispOH, resulting in 100% of enantiomeric excess. The Cunninghamella elegans fungus was also able to stereoselectively biotransform risperidone into (+)- and (−)-9-RispOH enantiomers at different rates.

Keywords: Solid phase microextraction; Chiral analysis; Stereoselective fungal biotransformation; Polar organic mode; Paliperidone; Risperidone

Ice photolysis of 2,2′,4,4′,6-pentabromodiphenyl ether (BDE-100): Laboratory investigations using solid phase microextraction by Lucia Sanchez-Prado; Konstantina Kalafata; Sanja Risticevic; Janusz Pawliszyn; Marta Lores; Maria Llompart; Nicolas Kalogerakis; Elefteria Psillakis (pp. 90-96).

Display Omitted► BDE-100 is photo-processed in ice solid samples. ► Ice photolysis kinetics for BDE-100 is similar to the one observed in water. ► Similarities in photoproduct arrays between ice and liquid water phases. ► CF-photo-SPME at 0°C allowed the detection of more photoproducts.Here, we report for the first time a laboratory investigation into the photochemical degradation of 2,2′,4,4′,6-pentabromodiphenyl ether (BDE-100) in ice solid samples using an artificial UV light source. Solid phase microextraction (SPME) was used as a sensitive extraction technique for monitoring trace amounts of the hydrophobic pollutant and its photoproducts. The results showed that ice photolysis kinetics for BDE-100 is similar to the one observed in the aqueous counterpart. The eight photoproducts identified consisted of brominated diphenyl ethers with lower bromine content and polybrominated dibenzofurans, suggesting two important photodegradation pathways for BDE-100 in ice solid samples: (i) stepwise reductive debromination and (ii) intramolecular elimination of HBr. Similarities in photochemical product arrays observed in the ice and water photolysis of BDE-100 were attributed to a similar mechanism for photochemical decomposition for both phases. Possible involvement of the water molecules in the reactions has been excluded by performing photolysis in D₂O ice solid and water samples. Taking advantage of the high preconcentration factor obtained with SPME at low temperatures, a SPME fiber cooled with liquid carbon dioxide down to 0°C was used as a photoreaction support for BDE-100 allowing the identification of a greater number of photoproducts.

Keywords: Ice photolysis; Organic pollutants; Brominated flame retardants; CF-photo-SPME

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Analytica Chimica Acta (v.742, #)