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1

High-performance liquid chromatography for analytical and small-scale preparative separation of (R,S)-mexiletine using (S)-(—)-(N)-trifluoroacetyl-prolyl chloride and (1S)-(—)-camphanic chloride and recovery of native enantiomer by detagging

Dixit S., Dubey R., Bhushan R.

Acta Chromatographica

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2014

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Vol. 26, no. 4

625--636

EN

A reversed phase high-performance liquid chromatographic method has been established for enantioseparation of (R, S)-mexiletine. Two volatile and thermally stable acyl chlorides, viz., (S)-(—)-(N)-trifluoro acetyl prolyl chloride and (1S)-(—)-camphanic chloride, were used as chiral derivatizing reagents. Binary composition of aqueous trifluoroacetic acid (0.1%)-acetonitrile as mobile phase was successful with ultraviolet (UV) detection at 210 nm. The method was optimized and validated for accuracy, precision, and limit of detection. The limit of detection was found to be 45 ng mL -1 and 80 ng mL -1 for the two types of diastereomers. Besides, kinetic resolution was achieved, and the experimental conditions optimized for this purpose provided diastereomeric excess up to 74% for (R)-isomer. On achieving a resolution value greater than 2, the optimized method for analytical enantioseparation was scaled-up to smallscale preparative level, and the native (R)-mexiletine was recovered by acid hydrolysis of the diastereomer.

2

Enantioseparation of amino alcohols by reversed-phase high-performance liquid chromatography using cyanuric chloride-based chiral derivatizing reagents having amino acids and their amides as chiral auxiliaries

Bhushan R., Lal M.

Acta Chromatographica

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2014

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Vol. 26, no. 3

413--427

EN

A high-performance liquid chromatographic (HPLC) method was developed for enantioresolution of amino alcohols using an indirect approach. Two sets of chiral derivatizing reagents (CDRs) having amino acids (CDRs 1–4; set A) and their amides (CDRs 5–8; set B) as chiral auxiliaries in cyanuric chloride (CC) moiety were synthesized and characterized. Diastereomers of eight amino alcohols were synthesized, under microwave irradiation, using each of the eight CDRs. The resulting diastereomers were separated by reversed-phase high-performance liquid chromatography (RP-HPLC) using C18 column and eluting mixtures of acetonitrile with aqueous trifluoroacetic acid (aq.TFA) in a linear gradient (45 min) with UV detection at 230 nm. The results (in terms of resolution Rs and retention factor k) obtained for the two sets of diastereomers were compared among themselves and among the two groups. The effects of chiral auxiliaries (in terms of acid and amides variants), constituting CDRs, on separation were also evaluated. The elution order for the diastereomers was determined. The separation method was validated for limit of detection (LOD), linearity, accuracy, precision, and recovery.

3

Wpływ modyfikatora fazy ruchomej na selektywność rozdzielenia w odwróconym układzie faz wysokosprawnej chromatografii cieczowej

Misiołek B., Klimek-Turek A., Dzido T. H.

Wiadomości Chemiczne

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2013

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[Z] 67, 1-2

133--159

EN

High performance liquid chromatography (HPLC) is an instrumental analytical technique, which is widely used for a separation and determination of a mixture of components in many samples (e.g. of biomedical, pharmaceutical, food, and environmental origin). Despite several decades of the development of this technique, some aspects of the chromatographic process are still open to questions. This is particularly related to mechanisms of retention and selectivity of a separation. Improvement of the separation selectivity can be achieved by a change of the stationary phase type and qualitative and/or quantitative composition of the mobile phase. The replacement of the stationary phase does not ensure a smooth change of selectivity and retention, however, it generates additional costs of analysis. Therefore, the optimal conditions of chromatographic separation can be easily obtained by the change of a composition of the mobile phase, i.e. the type and/or concentration of its modifier (organic solvent). This paper presents an overview of approaches to explanation and interpretation of an influence of mobile phase composition on the retention and separation selectivity in liquid chromatography systems with particular emphasis on modifier type of eluent in the reversed phase high performance liquid chromatography (RP HPLC).

4

Protein homogeneity testing by reversed-phase high-performance liquid chromatography of reduced and non-reduced samples

Minkiewicz P., Dziuba J., Niklewicz M.

Polimery

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2005

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T. 50, nr 5

379-382

EN

The concept of this study was based on the assumption that protein standards obtained using the same method may reveal heterogeneity explainable by changes in the disulphide bonding pattern. Two lots of bovine a-lactalbumin standard were subjected to reversed-phase high-performance liquid chromatography (RP-HPLC). One of them was homogenous. The other revealed the presence of two major fractions when non reduced. Neither RP-HPLC after protein reduction nor mass spectrometry showed differences between them. This indicates that one of the lots contained isomers with different locations of disulphide bonds. A comparison of RP-HPLC profiles obtained with and without reduction may be thus recommended as a tool for testing homogeneity of protein standards, especially those used in experiments involving denaturation.

PL

Wzorce białek izolowane tą samą metodą mogą wykazać heterogeniczność. Założono, że brak homogeniczności może być wyjaśniony występującymi różnicami w położeniu wiązań disiarczkowych. Dwie partie bydlęcej laktoalbuminy-a zostały poddane analizie przy pomocy wysokosprawnej chromatografii cieczowej z odwróconymi fazami (RP-HPLC). Jedna z partii była homogeniczna, a druga tworzyła dwie frakcje, jeśli przed analizą nie była zredukowana (rys. 1). Zarówno RP-HPLC jak i spektrometria mas nie wykazały różnicy między próbkami pochodzącymi z różnych partii, ale uprzednio zredukowanymi (rys. 1. i 2.). Wynik ten wskazuje, iż jedna z partii białka zawierała izomery różniące się położeniem wiązań disiarczkowych. Na podstawie niniejszego eksperymentu można polecić porównanie chromatogramów białka niezredukowanego oraz zredukowanego jako test służący badaniu homogeniczności wzorców białek. Test taki byłby szczególnie przydatny w przypadku próbek białek przeznaczonych do badań procesów denaturacji.

5

Badania nad rozdzielaniem mieszanin zawierających fenol i chlorofenole metodą wysokosprawnej chromatografii cieczowej z odwróconymi fazami (RP HPLC)

Starzyński S., Masłowska J.

Zeszyty Naukowe. Chemia Spożywcza i Biotechnologia / Politechnika Łódzka

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1999

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Z. 61

49-57

PL

W pracy przedstawiono wyniki badania czasów retencji i efekty rozdziału prostych mieszanin zawierających fenol i chlorofenole z grupy najbardziej toksycznych związków fenolowych. Badania wykonano metodą izokratycznej wysokosprawnej chromatografii cieczowej z odwróconymi fazami (RP HPLC), na kolumnach wypełnionych Lichrosorbem, modyfikowanym węglowodorowymi fazami chemicznie związanymi typu RP-8 i RP-18. Jako fazy ruchome stosowano: acetonitryt - metanol - woda (1:1:1), acetonitryl - woda (1:1 lub 2:3), i metanol - woda (3:2 lub 1:1), Dobre rozdzielenie mieszanin zawierających od 5 do 9 składników otrzymano przy wykorzystaniu di składnikowych faz ruchomych metanolu z wodą lub acetonitrylu z wodą o składzie (1:1). Opracowane warunki rozdzielania tych mieszanin w czasie od 8 do 17 min. mogą być z powodzeniem wykorzystane w praktyce do szybkich, rutynowych analiz związków fenolowych.

EN

The results of retention investigations and separations of simple mixtures of phenols and chlorophenois obtained on two columns, containing Lichrosorb, modified by RP-18 or RP-8 hydrocarbon bonded phase are presented in this work. Studies were performed by isocratic reversed-phase high-performance liquid chromatography (RP HPLC). Acetonitrile-water and methanol-water mixtures of various compositions were used as the mobile phase. Satisfactory separations of mixtures containing six to nine phenols or chlorophenols were obtained when methanol-water (1:1) or acetomtrile-water (1:1) eluents were applied as the mobile phase. The procedure is rapid (8 to 17 min.) and may be adopted for routine analysis.

6

The effect of the concentration of the ionic liquid didecyldimethylammonium lactate on the retention and separation of pyrimidine bases

Szymański M., Zapart J., Florek G., Szymański A.

Ars Separatoria Acta

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2012/2013

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No. 9/10

15--24

EN

Ionic liquids (IL) are new materials with a wide spectrum of use. Being a variable combination of an organic cation and an organic or inorganic anion, their have controllable properties. The effect of the ionic liquid added to the mobile phase on the separation of uracil derivatives is studied and demonstrated in this paper. The ionic liquid used was didecyldimethylammonium lactate, which has an advantageous effect on the separation of the analytes studied. Pyrimidine bases which were used as the test compounds are characterized by alkaline properties due to which so-called peak tailing is observed during separation. A methanol/water mixture was used as the mobile phase in the chromatographic analyses. Optimum separations were obtained for 8% levels of the organic modifier. The best separations of the test isomers were obtained for 0.01% IL added to the mobile phase. The findings obtained are evidence that the use of ionic liquids in HPLC is an efficient method for the separation of polar compounds: the duration of the analysis is shorter and the resulting peaks are sharp and symmetrical.