Jevgeni Parshintsev

Isolation of flavonoids from aspen knotwood by pressurized hot water extraction and comparison with other extraction techniques.

Pressurized hot water extraction (PHWE) conditions (time, temperature, pressure) were optimized for the extraction of naringenin and other major flavonoids (dihydrokaempferol, naringin) from knotwood of aspen. Extracts were analysed by GC-FID, GC-MS, HPLC-UV and HPLC-MS. The results were compared with those obtained by Soxhlet, ultrasonic extraction and reflux in methanol. Flavonoids were most efficiently extracted with PHWE at 150 degrees C and 220 bar with 35 min extraction time. Soxhlet with methanol gave slightly higher recoveries, but an extraction time of 48 h was required. Naringenin concentration was highest in knotwood (1.15% dry weight) and much lower in the sapwood. PHWE proved to be cheap, fast and effective for the isolation of biofunctional flavonoids from aspen knotwood, producing higher recoveries than 24 h Soxhlet extraction, sonication or 24 h reflux.

Ionic liquid-functionalized silica for selective solid-phase extraction of organic acids, amines and aldehydes

Three ionic liquid (IL)-functionalized silica materials, imidazolium, N-methylimidazolium and 1-alkyl-3-(propyl-3-sulfonate) imidazolium, were synthesised and applied in solid-phase extraction (SPE) of organic acids, amines and aldehydes, which are important compound families in atmospheric aerosol particles. 1-Alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica was tested as sorbent for SPE for the first time. The analytes were separated and detected by liquid chromatography-mass spectrometry (LC-MS). To confirm the results achieved by LC-MS, the acids were additionally determined by gas chromatography-mass spectrometry (GC-MS). The stability of the IL-functionalized silica materials was tested at low and high pH. The effect of the pH on the extraction was also informative of the retention mechanism of the materials. The results showed anion exchange to be the main interaction, but hydrophobic and π interactions and hydrogen bonding also played a role in the extraction. Extraction efficiencies for organic acids ranged from 87 to 110%, except for cis-pinonic acid (19-29%). Lower extraction efficiencies for amines and aldehydes confirmed that anionic exchange was the predominant interaction. Comparisons made with two commercial SPE materials--silica-based strong anion exchange (SAX) and polymer-based mixed-mode anion exchange and reverse-phase (MAX)--showed the IL-functionalized materials to offer different selectivity and better extraction efficiency than SAX for aromatic compounds. Finally, the new materials were successfully tested in the extraction of an atmospheric aerosol sample.

Interaction of a commercial lipid dispersion and local anesthetics in human plasma: implications for drug trapping by “lipid-sinks”

Interactions between Intralipid dispersion and local anesthetics (bupivacaine, prilocaine, and lidocaine) were investigated. The amount of bupivacaine (the most cardiotoxic analyte of the local anesthetics studied) entrapped in Intralipid in the presence of plasma was studied using an off-line filtration and solid phase extraction method combined with capillary zone electrophoresis for quantification of free unbound bupivacaine. To confirm interactions between the analytes and Intralipid at lower concentrations, direct injection mass spectrometry was used. The use of immobilized Intralipid chromatography-atmospheric pressure ionization–ion trap mass spectrometry in the study of interactions between drugs and Intralipid dispersion is demonstrated. Finally, interactions between Intralipid dispersion and local anesthetics were investigated by electrokinetic capillary chromatography. The electrophoretic mobility of the Intralipid dispersed phase was calculated using the iterative procedure and a homologous series of alkyl phenyl benzoates (C1–C6), and the retention factors for the analytes were determined.

Determination of organic compounds from wood combustion aerosol nanoparticles by different gas chromatographic systems and by aerosol mass spectrometry.

Organic compounds in atmospheric nanoparticles have an effect on human health and the climate. The determination of these particles is challenged by the difficulty of sampling, the complexity of sample composition, and the trace-level concentrations of the compounds. Meeting the challenge requires the development of sophisticated sampling systems for size-resolved particles and the optimization of sensitive, accurate and simple analytical techniques and methods. A new sampling system is proposed where particles are charged with a bipolar charger and size-segregated with a differential mobility analyzer. This system was successfully used to sample particles from wood pyrolysis with particle sizes 30-100nm. Particles were analyzed by four techniques: comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry, gas chromatography-time-of-flight mass spectrometry, gas chromatography-quadrupole mass spectrometry, and aerosol mass spectrometry (aerosol MS). In the chromatographic techniques, particles were collected on a filter and analyzed off-line after sample preparation, whereas in the aerosol MS, particle analysis was performed directly from the particle source. Target compounds of the samples were polyaromatic hydrocarbons and n-alkanes. The analytical techniques were compared and their advantages and disadvantages were evaluated. The sampling system operated well and target compounds were identified in low concentrations.

Particle-into-liquid sampler on-line coupled with solid-phase extraction-liquid chromatography–mass spectrometry for the determination of organic acids in atmospheric aerosols

In the present study, sample collection and preparation were directly integrated with a chromatographic system by coupling a particle-into-liquid sampler for the first time on-line with solid-phase extraction-liquid chromatography-tandem mass spectrometry. Several organic acids, such as adipic, hydroxyglutaric, mandelic, vanillic, cis-pinonic, pinic, azelaic and sebacic, were used in the research. For sample pretreatment and concentration, strong anion exchange material was used in the extraction. Sampling, extraction and analysis conditions were optimized to obtain reliable information about aerosol chemical composition. To evaluate the performance of the on-line coupled system, half of each sample was analysed on-line and the other half was derivatized and analysed off-line by gas chromatography-mass spectrometry. Comparison of the two techniques with use of t-test showed the results to be in an excellent agreement. Limits of detection of studied acids in on-line system were between 0.1 and 0.9 ng. The on-line coupled system is fast and reliable and a promising tool for the real time analysis of organic acids in atmospheric aerosols.

Solid-phase extraction of organic compounds in atmospheric aerosol particles collected with the particle-into-liquid sampler and analysis by liquid chromatography-mass spectrometry.

Atmospheric aerosol particles, collected with the particle-into-liquid sampler at SMEARII station in Finland in mid-August 2007, were analysed for biogenic acids. The sample pretreatment method, comprising solid-phase extraction with anion exchange and hydrophilic-lipophilic balance materials, was optimized. Extraction efficiencies of solid-phase extraction from 10 and 20ml samples were about 100%, with average relative standard deviation of 8.9%, in concentration range from 12.5 to 50ng/ml of the acid. Extraction of aldehydes was less successful, with efficiencies from 69 to 163% and average 10% deviation. Pretreated samples were analysed by reversed phase high performance liquid chromatography with ion trap mass spectrometric detection. Limits of detection achieved for organic acids with the analytical procedure developed ranged from 9 to 27microg/l of extracted sample, while limits of quantitation were from 31 to 90microg/l. Oxidation with ozone was used for the preparation of the acid of beta-caryophyllene (beta-caryophyllinic acid), which was also studied in aerosol samples. MS(2) experiments were used to confirm the identification of trans-pinic, trans-pinonic and beta-caryophyllinic acids. Azelaic, hexadecanoic, cis-pinonic, and cis- and trans-pinic acids were quantitated in the samples with use of authentic standards, while the concentrations of trans-pinonic and beta-caryophyllinic acids were determined with cis-pinonic acid as surrogate. Also, the contribution of beta-caryophyllene oxidation products to aerosol organic carbon was evaluated. Aldehydes could not be analysed in real samples due to the insufficient extraction. The particle-into-liquid sampler proved to be suitable for the collection of aerosol particles for the elucidation of daily and diurnal variation of selected species. The optimized sample pretreatment, together with the analysis method, offer a promising approach for the study of aerosol chemical composition, where artifact formation is minimal and time resolution is good.

Development of spoilage bacterial community and volatile compounds in chilled beef under vacuum or high oxygen atmospheres.

Research into microbial community development and metabolism is essential to understand meat spoilage. Recent years have seen the emergence of powerful molecular techniques that are being used alongside conventional microbiology approaches. This enables more accurate studies on meat spoilage. The aim of this study was to investigate the influence of packaging (under vacuum and in high oxygen atmosphere) on the development of microbial communities and metabolic activities at 6 °C by using culture-dependent (cultivation, ribotyping) and culture-independent (amplicon sequencing) methods. At the beginning of shelf life, the microbial community mostly consisted of Carnobacterium and Lactobacillus. After two weeks of storage, Lactococcus and Lactobacillus were the dominant genera under vacuum and Leuconostoc in high oxygen meat packages. This indicates that oxygen favoured the genus Leuconostoc comprising only heterofermentative species and hence potential producers of undesirable compounds. Also the number of volatile compounds, such as diacetyl, 1-octen-3-ol and hexanoic acids, was higher in high oxygen packages than under vacuum packages. The beef in high oxygen atmosphere packaging was detected as spoiled in sensory evaluation over 10 days earlier than beef under vacuum packaging. Leuconostoc gelidum, Lactococcus piscium, Lactobacillus sakei and Lactobacillus algidus were the most common species of bacteria. The results obtained from identification of the isolates using ribotyping and amplicon sequencing correlated, except for L. algidus, which was detected in both types of packaging by amplicon sequencing, but only in vacuum packaged samples using the culture-based technique. This indicates that L. algidus grew, but was not cultivable in high oxygen beef using the Nordic Committee on Food Analysis standard method.

Solid phase microextraction Arrow for the sampling of volatile amines in wastewater and atmosphere.

A new method is introduced for the sampling of volatile low molecular weight alkylamines in ambient air and wastewater by utilizing a novel SPME Arrow system, which contains a larger volume of sorbent compared to a standard SPME fiber. Parameters affecting the extraction, such as coating material, need for preconcentration, sample volume, pH, stirring rate, salt addition, extraction time and temperature were carefully optimized. In addition, analysis conditions, including desorption temperature and time as well as gas chromatographic parameters, were optimized. Compared to conventional SPME fiber, the SPME Arrow had better robustness and sensitivity. Average intermediate reproducibility of the method expressed as relative standard deviation was 12% for dimethylamine and 14% for trimethylamine, and their limit of quantification 10μg/L and 0.13μg/L respectively. Working range was from limits of quantification to 500μg/L for dimethylamine and to 130μg/L for trimethylamine. Several alkylamines were qualitatively analyzed in real samples, while target compounds dimethyl- and trimethylamines were quantified. The concentrations in influent and effluent wastewater samples were almost the same (∼80μg/L for dimethylamine, 120μg/L for trimethylamine) meaning that amines pass the water purification process unchanged or they are produced at the same rate as they are removed. For the air samples, preconcentration with phosphoric acid coated denuder was required and the concentration of trimethylamine was found to be around 1ng/m(3). The developed method was compared with optimized method based on conventional SPME and advantages and disadvantages of both approaches are discussed.

Aliphatic and aromatic amines in atmospheric aerosol particles: comparison of three ionization techniques in liquid chromatography-mass spectrometry and method development.

A complete methodology was developed for the determination of ten aliphatic and nine aromatic amines in atmospheric aerosol particles. Before the liquid chromatography - tandem mass spectrometric separation and determination, the derivatization reaction of the analytes using dansyl chloride was accelerated by ultrasounds. From three different ionization techniques studied electrospray ionization was superior in terms of sensitivity, linearity, repeatability and reproducibility over atmospheric pressure chemical ionization and photoionization for the target analytes. The method developed was validated for the gas phase, 30 nm and total suspended atmospheric aerosol particles. The method quantification limits ranged between 1.8 and 71.7 pg. The accuracy and the potential matrix effects were evaluated using a standard addition methodology. Recoveries from 92.1% to 109.1%, the repeatability from 0.6% to 8.4% and the reproducibility from 2.3% to 9.8% were obtained. The reliability of the methodology was proved by the statistical evaluation. Finally, the developed methodology was applied to the determination of the target analytes in eight size separated ultrafine particulate (Dp=30±4 nm) samples and in eight total suspended particulate samples collected at the SMEAR II station. The mean concentrations for aliphatic amines were between 0.01 and 42.67 ng m(-3) and for aromatic amines between 0.02 and 1.70 ng m(-3). Thirteen amines were quantified for the first time in 30 nm aerosol particles.

Modified zeolitic imidazolate framework-8 as solid-phase microextraction Arrow coating for sampling of amines in wastewater and food samples followed by gas chromatography-mass spectrometry.

In this study, a novel solid phase microextration (SPME) Arrow was prepared for the sampling of volatile low molecular weight alkylamines (trimethylamine (TMA) and triethylamine (TEA)) in wastewater, salmon and mushroom samples before gas chromatographic separation with mass spectrometer as detector. Acidified zeolitic imidazolate framework-8 (A-ZIF-8) was utilized as adsorbent and poly(vinyl chloride) (PVC) as the adhesive. The custom SPME Arrow was fabricated via a physical adhesion: (1) ZIF-8 particles were suspended in a mixture of tetrahydrofuran (THF) and PVC to form a homogeneous suspension, (2) a non-coated stainless steel SPME Arrow was dipped in the ZIF-8/PVC suspension for several times to obtain a uniform and thick coating, (3) the pore size of ZIF-8 was modified by headspace exposure to hydrochloric acid in order to increase the extraction efficiency for amines. The effect of ZIF-8 concentration in PVC solution, dipping cycles and aging temperature on extraction efficiency was investigated. In addition, sampling parameters such as NaCl concentration, sample volume, extraction time, potassium hydroxide concentration, desorption temperature and desorption time were optimized. The Arrow-to-Arrow reproducibilities (RSDs) for five ZIF-8 coated Arrows were 15.6% and 13.3% for TMA and TEA, respectively. The extraction with A-ZIF-8/PVC Arrow was highly reproducible for at least 130 cycles without noticeable decrease of performance (RSD<12.5%). Headspace SPME of 7.5mL sample solution with the fabricated ZIF-8 coated Arrow achieved linear ranges of 1-200ngmL-1 for both TMA and TEA. The limit of quantitation (LOQ) was 1ngmL-1 for both TMA and TEA. The method was successfully applied to the determination of TMA and TEA in wastewater, salmon and mushroom samples giving satisfactory selectivity towards the studied amines.