Separation of Chlorins and Carotenoids in Capillary Electrophoresis

The present study reports the investigation of capillary electrophoresis (CE) for the separation of the photosynthetic pigments (chlorophyll derivatives as well as carotenoids) together. Various CE methods, such as micellar electrokinetic chromatography, capillary electrokinetic chromatography, and nonaqueous capillary electrophoresis (NACE) are tested, with coated and uncoated capillary columns to evaluate optimal separation conditions using diode array detection. The effect of different type and composition of organic solvents and surfactants on the separation is discussed. Detection limits are found in the range of 1.14-2.45 ppm. According to the system suitability results, the most effective separation is observed using NACE with Aliquat 336 as cationic surfactant in coated capillary and mixture of MeOH-ACN-THF (5:4:1, v/v/v) as solvent. Quantitative evolution is investigated, and recovery percentage values are found to be 96.7-102

Separation and determination of polyaromatic hydrocarbons by capillary electrokinetic chromatography

Poliaromatik hidrokarbonların (PAH çevrede bulunma sıklığı ve insan sağlığı üzerindeki zararlı etkileri nedeniyle bu bileşikler, pek çok alanda ön plana çıkmakta ve bunların bir karışımdan ayrılarak tayinleri de önem kazanmaktadır. Bu çalışmada sodyum dodesilbenzensülfonat (SDBS), hidrofobik poliaromatik hidrokarbonların (PAH) su-organik faz ortamında elektrokinetik kromatografi yöntemi ile ayrılmalarında sahte sabit faz olarak kullanılmıştır. PAH moleküllerinin, SDBS iyonu ile solvofobik etkileşimi sonucu negatif yük kazanan PAH türleri, elektrik alan altında hareket edebilirler. Böylece farklı halka (1-5) sayısına sahip 8 adet PAH ve 3 adet aromatik bileşik içeren örnek karışımının 130.000-230.000 arası teorik plaka etkinliği ile ayırımı başarılmıştır. Geliş zamanına göre bağıl tekrarlanırlık değerleri % 1.15-1.55 RSD, pik alanına göre ise % 2-9 RSD arasındadır.  Anahtar Kelimeler: Poliaromatik hidrokarbonlar, sodyum dodesilbenzensülfonat, kapiler elektroforez, elektrokinetik kromatografi.Due to the abundance of polyaromatic hydrocarbons (PAHs) in the environment and the adverse health effects to which they have been linked, these compounds have been the focus of considerable attention in a number of areas including chemical separations. Especially, nowadays due to many advantages of the capillary electrophoresis technique (CE), detection and analyses of these kinds of compounds by using CE have become more important. In order to separate nonionic compounds in CE, an interaction with a charged carrier in the buffer should be provided. Both PAHs can be separated in CE by using additives which cause selectivity change and resolution of PAHs having the same electrophoretic mobility, not only due to electrostatic interaction but also due to a combination of other effects like hydrophobicity, hydrogen bonding, dipole-dipole interaction, etc. Sodium dodecylbenzenesulfonate (SDBS) was evaluated as potential pseudo-stationary phase for the separation of highly hydrophobic polycyclic aromatic hydrocarbons (PAHs) with electrokinetic chromatography in aqueous-organic media. PAH molecules undergo a solvophobic interaction with the SDBS ion, forming negatively charged species that can migrate in an electric field. Thus electrophoretic separations of 8 PAHs and 3 aromatic compounds having different ring numbers (1-5) were achieved with efficiencies between 130.000-230.000 theoretical plates. Reproducibilities of migration times range between 1.15 and 1.55 %RSD and peak areas between 2 and 9 %RSD. Keywords: Polyaromatic hydrocarbons, sodium dodecylbenzenesulfonate, capillary electrophoresis, electrokinetic chromatography

Investigation of Hopanoid Biomarkers in Lake Sediments by GC-MS and RP-HPLC-APCI-MS

Hopanoids are mainly derived from bacteriohopanpolyols that occur especially in bacteria, show the importance of bacterial lipid contributions in geological materials. In this work, GC-MS and RP-HPLC-APCI-MS analyses of hopanoid biomarkers in oxic and anoxic sediment samples from Lake Cadagno (Swiss Alps) and Lake Voua de la Motte (Haute Savoie, France) are presented and discussed. Samples were ultrasonically extracted, fractionated by flush chromatography on silica gel and derivatised before the analyses. Periodic acid/ sodium borohydride cleavage was used to identify highly functionalised hopanoid

Separation of Chlorins and Carotenoids in Capillary Electrophoresis

The present study reports the investigation of capillary electrophoresis (CE) for the separation of the photosynthetic pigments (chlorophyll derivatives as well as carotenoids) together. Various CE methods, such as micellar electrokinetic chromatography, capillary electrokinetic chromatography, and nonaqueous capillary electrophoresis (NACE) are tested, with coated and uncoated capillary columns to evaluate optimal separation conditions using diode array detection. The effect of different type and composition of organic solvents and surfactants on the separation is discussed. Detection limits are found in the range of 1.14–2.45 ppm. According to the system suitability results, the most effective separation is observed using NACE with Aliquat 336 as cationic surfactant in coated capillary and mixture of MeOH-ACN-THF (5:4:1, v/v/v) as solvent. Quantitative evolution is investigated, and recovery percentage values are found to be 96.7–102%

Metal Analyses in Environmental and Pharmaceutical Samples by Capillary Electrophoresis with Methyl 3-Amino-3-(pyridin-3-yl)propanoate Dihydrochloride as a New Ion-Pairing Reagent

Separation and determination of some common metal ions was achieved with methyl 3-amino-3-(pyridin-3-yl)propanoate dihydrochloride (MAPP) as an ion-pairing reagent and pyridine as a detectable counter-ion for indirect UV detection at 254 nm. The effects of the complexing reagent and chromophore concentrations, applied voltage, and organic solvent content on the separation were investigated. The optimized separation was carried out in a running electrolyte containing 16 mM MAPP and 20 mM pyridine at pH 4.0 and was successfully applied to the qualitative and quantitative analysis of Li+, Na+, Mg2+, Ca2+, Ba2+, Ni2+, and Zn2+ in pharmaceutical vitamin preparations and various water samples

Capillary electrokinetic separation of polycyclic aromatic hydrocarbons using cetylpyridinium bromide

Polycyclic aromatic hydrocarbons (PAHs) including isomeric pairs were separated in capillary electrokinetic chromatography using a cationic surfactant cetylpyridinium bromide (CPBr) as additive. With addition of 2 mM CPBr into the running electrolyte, dynamic coating occurs in the capillary and EOF is reversed. Changes of electroosmotic and electrophoretic mobilities with increasing CPBr concentration were investigated. Under optimum separation conditions, running electrolyte contains 50% MeCN, 20 mM acetate, and 40 mM CPBr at pH = 4.0. Using high concentration of organic solvent, aggregation of surfactants into micelles is prevented. Significant retentions indicate solvophobic, n- and π-electron interactions between CPBr monomers and PAHs

Effect of cetyltrimethylammonium bromide on the migration of polyaromatic hydrocarbons in capillary electrokinetic chromatography

The separation of different ring numbered polyaromatic hydrocarbons (PAHs) was accomplished by using cetyltrimethylammonium bromide (CTAB) in capillary electrokinetic chromatography. In order to increase the solubilities and selectivities of PAHs, acetonitrile (ACN) was used as an organic modifier. Under the optimised conditions, 11 aromatic compounds were separated within 14.5 min in a running electrolyte containing 10 mM phosphate, 30 mM CTAB, and 40% ACN at pH 6.0. The effects of CTAB and ACN concentrations, voltage and pH on the resolution were investigated. Reproducibilities of migration times range between 0.55 and 1.27 R.S.D.% and peak areas between 1.02 and 7.23 R.S.D.%. Limit of detections (LODs) range between 0.09 and 2.24 μg ml−1. This new and fast separation method of PAHs was applied to cooked oil sample

Direct determination of valproic acid in biological fluids by capillary electrophoresis with contactless conductivity detection

Capacitively coupled contactless conductivity detection (C(4)D) is a new technique providing high sensitivity in capillary electrophoresis (CE) especially for small ions that can otherwise only be determined with indirect methods. In this work, direct determination and validation of valproic acid (VPA) in biological fluids was achieved using CE with C(4)D. VPA is of pharmacological interest because of its use in epilepsy and bipolar disorder. The running electrolyte solution used consisted of 10mM 2-(N-morpholino)ethane sulfonic acid (MES)/dl-histidine (His) and 50microM hexadecyltrimethylammonium bromide (HTAB) at pH 6.0. Caproic acid (CA) was selected as internal standard (IS). Analyses of VPA in serum, plasma and urine samples were performed in less than 3min. The interference of the sample matrix was reduced by deproteinization of the sample with acetonitrile (ACN). The effect of the solvent type and ratio on interference was investigated. The limits of detection (LOD) and quantitation (LOQ) of VPA in plasma samples were determined as 24 and 80ng/ml, respectively. The method is linear between the 2 and 150microg/ml, covering well the therapeutic range of VPA (50-100microg/ml)

Enantioseparation of baclofen with highly sulfated β-cyclodextrin by capillary electrophoresis with laser-induced fluorescence detection

The enantioseparation of baclofen (4-amino-3-p-chlorophenylbutyric acid) was achieved by CE-LIF with highly sulfated -CD (HS--CD) as chiral selector. Naphthalene-2,3-dicarboxaldehyde was used for the derivatization of nonfluorescent baclofen. HS--CD (2%) containing 50 mM borate buffer at pH 9.5 was chosen as the optimal running electrolyte and applied to the analysis of baclofen enantiomers in human plasma. The linearity of calibration curves (R 2 0.998) for R-(-) and S-(+)-baclofen was in the 0.1-2.0 M concentration range. After a simple ACN-protein precipitation, the LOD of baclofen in plasma sample was found as low as 50 nM