Wyniki wyszukiwania - Biblioteka Nauki

1

A study on optimization of sample preparation for gas chromatographic methods used in routine irradiated foodstuffs detection

100%

Virgolici M. , Medvedovici A. V. , Manea M. M. , Cutrubinis M. , Moise I. V. , Georgescu R.

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2009

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tom Vol. 54, No. 2

115-121

EN

The study is focused on the optimization and minimization of sample preparation procedures given in EN 1784 and EN 1785 standardized methods for the detection of irradiated foodstuffs which contain fats. The techniques used in this study were gas chromatography (GC) with a flame ionization detector (FID) for hydrocarbons (HC) detection and GC coupled with mass spectrometry (MS) for 2-alkylcyclobutanones detection. Our work revealed that alternative extraction and clean-up procedures as well as alternative injection modes like large volume injection can significantly reduce the total analysis time and costs with comparable results.

2

Simultaneous determination of 223 pesticides in tobacco by GC with simultaneous electron capture and nitrogen-phosphorous detection and mass spectrometric confirmation

80%

Lozowicka B. , Rutkowska E. , Hrynko I.

Open Chemistry

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2015

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tom 13

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nr 1

EN

LSE (liquid-solid extraction), MSPD (matrix solid phase dispersion) and QuEChERS (quick, easy, cheap, effective, rugged and safe) extractions followed by GC-μECD/NPD to determine 223 pesticide residues in tobacco simultaneously were developed and compared. The identities of ten model pesticides were confirmed by GC-MS/MS. The type and amount of dispersant (Florisil, silica gel and alumina), sample mass, cleanup adsorbent, and the eluent (hexane, acetone and acetonitrile) were optimized. Linearity, recovery, LOQ, LOD, and matrix effect were compared. Most recoveries were 71−120% (RSD < 18%). LOD and LOQ were much lower than the CORESTA GRLs. The best method was QuEChERS: acetonitrile extraction and dispersive solid-phase extraction using primary-secondary amine and graphitized carbon.

3

Chromatograficzne badanie oddziaływań w układach polimerowych

80%

Milczewska K. , Voelkel A.

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tom T. 85, nr 8-9

953-955

PL

Badano grupę kompozycji polimerowych, zawierających modyfikowane napełniacze, metodą odwróconej chromatografii gazowej. Właściwości poszczególnych materiałów, polimerów i napełniaczy oraz ich mieszanin opisano za pomocą parametrów Flory–Hugginsa. Podjęto próbę wyznaczenia parametru niezależnego od stosowanego związku testowego wg procedury Zhao–Choi.

EN

Silica modified with N-2-aminoethyl-3-aminopropyltrimethoxysilane (I) or octyltriethoxysilane (II) was used to fill, 5, 10 or 20%, a polybutadiene-urethane oligomer (M = 4000). This was examd. by inverse gas chromatog. to det. Flory-Huggins χ∞ 12 -parameters in 10 binary systems with solvent-type test compds. Zhao-Choi (Polymer, 42, 1075 (2001)) method was also tried to det. χ' 23 independent of the test compd. Results were consistent. The modified SiO2-filled composites interacted strongly (with CHCl3 and Et2O, lowest χ∞ 12). More II made interactions weaker (except for dichloroethane). I-modified SiO2 was effective at 5%. The χ' 23 (measure of oligomer–filler interactions) showed modified SiO2 to be most effective at 5 and 10% (363, 393 K).

4

IGC w charakterystyce powierzchni ciał stałych

80%

Voelkel A.

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tom T. 82, nr 8-9

801-802

5

Metoda poprawy precyzji analiz chromatograficznych gazów ziemnych poprzez kontrolowany sposób wprowadzania próbki na analizator w warunkach "barostatycznych"

80%

Rosłonek G. , Bojewski J. , Sobczak M.

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tom Nr 4

7-9

EN

Assumptions of a new way of introducing portions of natural gas into a chromatographic analyzing device in conditions of controlled pressure of the analyzed gas sample. Technical details of the system. Main advantages of the method.

6

The influence of aniline radicals concentration in the stationary phase on the retention in gas chromatography

80%

Nasuto R.

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tom Vol. 72, nr 10

2303-2311

EN

Four adsorbents with chemically bounded aniline radicals on silica gel surface of concentration 2.94; 5.86; 6.47 and 7.81 mymole/m(2) were prepared. On packed chromatographic column with unmodified silica gel Si 100 and obtained adsorbents the retention times of aliphatic (C6-C12) and aromatic (benzene, toluene and m-xylene) hydrocarbons and polar organic compounds (chloroform, ethylene chloride, chlorobenzene, p-chlorotoluene and ethyl benzene) were measured. Retention times, obtained on column with packing of the highest concentration of the bounded phase, were shorter than those on column with unmodified silica gel Si 100. Thus, there exists a possibility of optimization of retention of chemical compounds by change of their phase concentration on the support surface.

7

Wyznaczanie objętości kapilary pomiarowej zaworu sześciodrożnego w chromatografii gazowej

80%

Czech K. , Słomkiewicz P. M.

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tom T. 16, nr 2

93-98

PL

Przedstawiono metodę pomiaru objętości kapilar dozowniczych, złączy gazowych i wewnętrznych kanalików zaworów sześciodrożnych używanych do pobierania próbek w chromatografii gazowej. Objętości oznaczano wagowo rtęcią. Określono wpływ temperatury zaworu sześciodrożnego z kapilarą dozowniczą na wielkość pobieranej próbki.

EN

The method of measurement of volume the sample loop, gas joints and the internal channels of six-port valves used to taking the samples in gas chromatography. The volumes were marked by weight of mercury. The effect of temperature six-port valve with sample loop on quantity of taken sample was determined.

8

Dozowanie próbek gazów do kolumny chromatograficznej o podwyższonym ciśnieniu

80%

Czech K. , Słomkiewicz P. M.

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tom T. 16, nr 2

29-33

PL

Opracowano metodę dozowania próbek gazowych do kolumn chromatograficznych o podwyższonym ciśnieniu za pomocą strzykawki i zbudowano urządzenie służące do tego celu. Wykonano badania określające przydatność skonstruowanego urządzenia w porównaniu do tradycyjnej strzykawki do próbek gazowych.

EN

The method of gas sampling by syringe to high pressure chromatography column was elaborated and the apparatus used to this aim was built. The usefulness investigations for comparison constructed device to traditional syringe to gas samples were made.

9

Chemical modification of silica surface by bonding ketoimine groups for SPE

80%

Rykowska I. , Wasik W.

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tom No. 6

41-52

EN

The applicability of silica gels, modified with ketoimine groups, in solid-phase extraction was tested. The surface characteristics of the modified silica was determined by elemental analysis, NMR spectra for the solid phases (29Si CP MAS NMR), analysis of pore size distribution of the silica support, and nitrogen adsorptiondesorption. The newly proposed sorbents with ketoimine groups were used for extraction of endocrine-disruptor compounds, extracted from water and powder milk. The properties of the sorbents were compared with commercial C18 ones.

10

Electron beam irradiation of r-SANEX and i-SANEX solvent extraction systems : analysis of gaseous products

80%

Szreder T. , Kocia R.

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tom Vol. 60, No. 4, part 2

899--905

EN

1-Octanol/kerosene mixtures and water contacted with organic solvents were used as model solutions for r-SANEX and i-SANEX extractions systems. Investigations aimed on a quantitative evaluation of gaseous products generated in these systems under exposure to an electron beam irradiation. Influence of O2, HNO3 and the presence of model ligands and complexes on the radiation chemical yields was studied. Relatively high G(H2) values (up to 420 nmol∙J-1) for the organic phase compromise the safety issues of the extraction process and should be considered on the stage of extraction apparatus design. Based on the obtained results gaseous hydrocarbons seem to have negligible impact on safety issue. The upper limit of G(H2) values in water contacted with organic phase was established to be 85 nmol∙J-1. This value is relatively low, however, the literature data indicate that G(H2) values measured in aqueous solutions are over twice higher for α-particles irradiation than for electron beam or γ-irradiation. Thus, further investigations of these systems are necessary.

11

Simultaneous determination of 11 preservatives in cosmetics and pharmaceuticals by matrix solid-phase dispersion coupled with gas chromatography

80%

Liu Y.-f. , Zhang J.-l. , Nie X.-f. , Zhang P. , Yan X.-q. , Fu K.-f.

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2020

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tom Vol. 32, no. 3

203--209

EN

A convenient method was developed for simultaneous determination of 11 preservatives in cosmetics and pharmaceuticals. Matrix solid-phase dispersion had been optimized as the sample pretreatment technology, using Florisil as a dispersant, anhydrous sodium sulfate as a dehydrant, formic acid as an additive, and n-hexane and ethyl acetate as eluents successively, and followed by gas chromatography–flame ionization detection on a TR-5 capillary column. Experimental results showed that 11 preservatives were baseline separated within 22 min. Good linearities were observed in the concentration range of 0.53–250 μg/mL for all analytes, and there were also minor differences. All correlation coefficients (r) were more than 0.995. The average recoveries at 3 levels of spiked samples ranged from 80% to 124% with 0.9–12% intra-day RSD and 1.8–12% inter-day RSD. The limits of detection were less than 0.18 μg/mL for all analytes. Besides, there was no obvious matrix effect on the analytes. The conclusion was that the developed method was simple, cheap, accurate, precise, and environment-friendly, in addition to existing little matrix effects. It could be recommended to determine 11 preservatives individually or in any their combinations to not only in liquid and gel cosmetics but also in liquid medicine and ointment.

12

Polyaniline-polypyrrole coating for solid phase microextraction

80%

Vickackaite V. , Ciuvasovaite V.

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tom 5

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nr 3

727-738

EN

A procedure for direct electrochemical deposition of polyaniline-polypyrrole blend coating on the surface of stainless steel wire was suggested. Incorporation of polyaniline and polypyrrole into the blend coating was confirmed by infrared spectroscopy. Key parameters (pyrrole, aniline, dopant and sulphuric acid concentrations and deposition potential) influencing the coating’s mechanical stability and surface homogeneity were optimised and thermostability of the coating was investigated. A possibility to apply the coating as a new fibre for solid phase microextraction was demonstrated. The coating showed better selectivity toward aromatic, hydrophobic compounds. [...]

13

Some remarks on gas chromatographic challenges in the context of green analytical chemistry

80%

Wardencki W. , Namiesnik J.

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2002

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tom 11

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nr 2

EN

As researchers involved in chromatography for 30 years we would like to present three approaches of implementation of principles of green chemistry into gas chromatography

14

Application of dispersive liquid—liquid microextraction for the analysis of organophosphorus pesticides in Hawthorn (Crataegus pinnatifida var. major) juice samples

70%

Ren Q. , Xia T.

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2016

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tom Vol. 28, no. 3

403--414

EN

Dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography equipped with flame photometric detection (GC—FPD) is introduced to extract and determine the fifteen organophosphorus pesticides (OPPs) in hawthorn (Crataegus pinnatifida var. major) juice samples. Some parameters affecting the DLLME efficiency, such as the type and volume of extraction and dispersive solvents, extraction time, and salt concentration, were studied and optimized. The optimized extraction and dispersive solvents are trichloroethane and acetonitrile, respectively. Good linearity was ranged from 0.5 to 100 ng mL−1 with correlation coefficients from 0.9991 to 0.9999. The limits of quantification (LOQs) varied from 0.15 to 0.3 ng mL−1, and the limits of detections (LODs) ranged from 0.05 to 0.1 ng mL−1. The relative standard deviations (RSDs) varied from 1.0% to 2.8% (n = 6) with the relative recoveries in the range of 85.6–119.1%. The method was successfully applied in the determination of OPPs in ten commercial hawthorn juice samples. The chlorpyrifos was detected in one sample.

15

Development of ultrasound-assisted extraction followed by solid-phase extraction followed by dispersive liquid–liquid microextraction followed by gas chromatography for the sensitive determination of diazinon in garden parsley as vegetable samples

70%

Rezaee M. , Khalilian F. , Pourjavid M. R.

Acta Chromatographica

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2023

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tom Vol. 35, no. 4

347--353

EN

A new pretreatment method termed ultrasound-assisted extraction (UAE) which is combined with solid-phase extraction which is combined with dispersive liquid-liquid microextraction (SPE-DLLME) followed by gas chromatography-flame ionization detector (GC-FID) analysis has been developed for the determination of diazinon in garden parsley as vegetable samples. The analyte was extracted from garden parsley sample using ultrasound-assisted extraction followed by solid-phase extraction followed by dispersive liquid-liquid microextraction. Various parameters that affect the efficiency of the extraction techniques have been optimized. The calibration plot was linear in the range of 5.0–1,000 μg kg⁻¹ with detection limit of 1.0 μg kg⁻¹ for diazinon in garden parsley samples. The results confirm the suitability of the UAE-SPE-DLLME-GC-FID as a sensitive method for the analysis of the targeted analyte in garden parsley samples.

16

Isolation and characterisation of bacteria degrading polycyclic aromatic hydrocarbons : phenanthrene and anthracene

70%

Nzila A. , Sankaran S. , Al-Momani M. , Musa M. M.

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tom Vol. 44, no. 2

43--54

EN

The aim was to isolate and characterise bacteria that can be used to degrade phenanthrene and anthracene. Bacteria were isolated by enrichment of contaminated soil in mineral medium. Growth profiles were assessed by colony forming units (CFU). Electron microscopy and 16S rRNA gene sequencing were employed to characterise these bacteria. Growth profiles were quantified by analysing the culture doubling time, and both the quantification of utilisation of aromatic compounds and the detection of phenanthrane metabolites were carried out by gas chromatography and mass-spectrometry. Two co-cultures of phenanthrene- and anthracene-biodegrading bacteria (PHEN-Cult and ANT-Cult, respectively) were isolated and characterised. The two co-cultures grew rapidly, reaching maximum counts of 1010 CFU/mL, within 2–10 days. The doubling time (dt) fell between 0.5–1.5 day (at PHEN and ANT concentrations of 1–100 ppm), making them among the most active PAH degrading microorganisms described so far. PHEN-Cult consists of two strains, Pseudomonas citronellolis, PHC3Z1A, and Stenotrophomonas maltophilia, JPHC3Z2B, while ANT-Cult is made of Ralstonia pickettii, JANC1A and Thermomonas haemolytica, JANC2B. Both co-cultures were more active at pH 7, 0–4% NaCl, and 37–40°C. They were also able to utilise naphthalene, salicylic acid and catechol. Starting with 100 ppm, within 15 days, 50–75% of PHEN and ANT were degraded, and the following were the PHEN metabolites that were identified: 3-naphthyl-allyl alcohol, phthalic acid ethyl diester, 2-hydroxybenzalpyruvic acid-methyl ester. These bacteria are appropriate for the removal of PHEN and ANT in contaminated environments, thus further studies are warranted to establish their ability to remove these PAHs in pilot and large scale.

17

Studies on carcinogenic PAHs emission generated by vehicles and its correlation to fuel and engine types

70%

Kumar V. , Kothiyal N. C. , Saruchi

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nr 1

48-58

EN

The objective of this study was to find major PAHs produced in ambient air from the automobile exhaust as a function of fuels (diesel, petrol, and biodiesel) and engine type qualitatively and quantitatively. The recovery range was found between 30% and 70%. The study was carried out on two, three, and four wheelers. Biodiesel samples tested in the study were synthesized indigenously from different starting raw materials and analyzed for PAHs concentration in the exhaust on a Honda genset (EBK 2000AC Model). Biodiesel samples were blended with diesel in different ratio (25:75, 35:65 and 45:55) to investigate the exhaust behavior. Biodiesel was blended with Diesel the concentration of almost all PAHs reduces in comparison to pure Diesel exhaust. B(a)A and B(a) P was the common PAH found in higher concentration in almost all fuels. FTIR results indicate esterification of vegetable oil and NMR results indicate a complete conversion of oils into biodiesel.

18

Oznaczanie migracji eta-Caprolaktamu z wyrobów z tworzyw sztucznych metodą chromatografii gazowej

70%

Groman A. , Guberska J.

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1999

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tom T. 44, nr 9

618-622

PL

Opracowana metoda dotyczy migracji eta-kaprolaktamu (KL) z wyrobów z tworzyw sztucznych kontaktujących się z żywnością do różnych wodnych płynów modelowych (woda, roztwory alkoholu etylowego - 15-proc. i kwasu octowego - 3-proc.)- Jako wzorzec wewnętrzny zastosowano 1,6-heksa-nodiol. W określonych warunkach, czasy retencji (t,) KL i 1,6-heksanodiolu wynosiły odpowienio 19,4 i 17,2 min (rys. 1). Opracowano również warunki oznaczania migracji KL do oleju słonecznikowego (ekstrakcja wodą, dodanie wzorca wewnętrznego do oleju przed ekstrakcją). Wykrywalność opracowanych metod wynosi 3 mg/kg płynu modelowego, podczas gdy limit migracji specyficznej w przypadku KL jest równy 15 mg/kg. Błąd względny opisanych metod nie przekracza 10%, a względne odchylenie standardowe RSDr jest mniejsze niż 8.

EN

eta-Caprolactam migrated from plastic packaging materials into food simulants (water, aqueous 15% ethanol, and aqueous 3% acetic acid) was determined by GC. 1,6-Hexanediol was used as the internal standard. Under specified conditions, the retention times of s-caprolactam and 1,6-hexanediol were 19.4 and 17.2 min, respectively (Fig. 1). Migration of eta-caprolactam into sunflower oil (extraction with water and addition of the internal standard prior to the extraction) was also studied. The detectability of the method was found to be 3 mg/kg food simulant. For eta-caprolactam, the specific migration limit is 15 mg/kg. The relative error of the method was found to be maximum 10%, and the relative standard deviation was lower than 8.

19

Liquid phase microextraction techniques combined with chromatography analysis: a review

70%

Dugheri S. , Mucci N. , Bonari A. , Campagna M. , Montalti M. , Arcangeli G. , Ubiali D. , Marrubini G. , Cappelli G.

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tom Vol. 32, no. 2

69--79

EN

Sample pretreatment is the first and the most important step of an analytical procedure. In routine analysis, liquid–liquid microextraction (LLE) is the most widely used sample pre-treatment technique, whose goal is to isolate the target analytes, provide enrichment, with cleanup to lower the chemical noise, and enhance the signal. The use of extensive volumes of hazardous organic solvents and production of large amounts of waste make LLE procedures unsuitable for modern, highly automated laboratories, expensive, and environmentally unfriendly. In the past two decades, liquid-phase microextraction (LPME) was introduced to overcome these drawbacks. Thanks to the need of only a few microliters of extraction solvent, LPME techniques have been widely adopted by the scientific community. The aim of this review is to report on the state-of-the-art LPME techniques used in gas and liquid chromatography. Attention was paid to the classification of the LPME operating modes, to the historical contextualization of LPME applications, and to the advantages of microextraction in methods respecting the value of green analytical chemistry. Technical aspects such as description of methodology selected in method development for routine use, specific variants of LPME developed for complex matrices, derivatization, and enrichment techniques are also discussed.

20

PURITY DETERMINATION OF THE STARTING MATERIALS USED IN THE SYNTHESIS OF PHARMACEUTICAL SUBSTANCES

70%

Groman A. , Stolarczyk E. , Mucha M.

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nr 1

29-35

EN

High requirements on the API quality mean that the quality control of the starting material is crucial to the manufacturing process of drug substances. Three sensitive methods for the purity determination of the following starting materials: ethylene glycol (method I), 3-acetylpyridine (method II) and 4-chloromethyl-5-methyl-1,3-dioxol-2-one (method III) used in the synthesis of selected drug substances were developed using GC-FID techniques. All the methods were validated according to the International Conference on Harmonization guidelines. The correlation coefficient values were found about 0.99. The obtained RSD values from the replicate injections in the range of 20 - 120% of the nominal concentration ensured the precision.