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PubMed1999

[Separation of alkylphenols in oil field water by micellar electrokinetic chromatography].

The abundance of alkylphenols in the system of water, oil and rock is of great geochemistry significance. The analysis of alkylphenols in oil field water using micellar electrokinetic chromatography with UV detection is described. The different variables that affect separation were studied and optimized. The results show that better separation was obtained with the borate concentration of 47.5 mmol/L, the SDS concentration of 70.0 mmol/L, pH 9.15, separation current of 100 microA, capillary temperature 20 degrees C. The organic additive(beta-CD) could partly improve separation. Water sample was introduced into the capillary by pressure of 5 kPa for several seconds. Detection wavelength was 200 nm and reference wavelength at 350 nm for all experiments. For the oil field water sample, the reproducibility of directly injected oil field water after filtration through a membrane filter of 0.45 micron pore size was far from good and it's concentrations of alkylphenols were too low to be detected. Therefore, a method of separation and enrichment by a column packed with tributyl phosphate(TBP) extraction resin was applied for analysis of TZ4 oil field water. Qualitative analysis show that there are phenol, o-cresol, m-cresol and p-cresol in this water sample and phenol is the main component and it's quantity is more than other alkylphenols. It's recoveries from the oil field water were 91.5%-95.3%. The results were satisfactory.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2001

[Separation and quantitative analysis of ginkgolic acids from Ginkgo biloba leaves by reverse phase argentation high performance liquid chromatography].

AIM: To develop a reverse phase argentation high performance liquid chromatographic (RP-AHPLC) method for the separation and determination of ginkgolic acids. METHODS: Liquid chromatography-electrospray ionization mass spectrometry (LC/ESI-MS) was applied to identify ginkgolic acids from Ginkgo biloba leaves and four ginkgolic acids of the samples were separated and quantified by RP-AHPLC. Leaves were extracted with ethanol and analytes were extracted with hexane after addition of acid/salt solution and adsorbent to matrix solution. Ginkgolic acids were separated and determined within 30 minutes by RP-AHPLC under optimum chromatographic conditions. Methanol and 5% aqueous acetic acid (90:10) containing 0.03 mol.L-1 silver ion was used as mobile phase, column temperature was selected at 30 degrees C, flow rate was 1.0 mL.min-1, UV detection wavelength was at 310 nm. The spectra analysis and purity identification of chromatographic peaks of ginkgolic acids were further confirmed by means of diode array detection. RESULTS: Four ginkgolic acids were baseline separated from each other and from other interfering components. The average recovery and relative standard deviation of the method were 97.3% and 1.6%, respectively. CONCLUSION: RP-AHPLC was an excellent method for separation of homologous with different carbon atom numbers and double bond. The method is useful for the quality control of extract of Ginkgo biloba leaves.

Chromatography, High Pressure Liquid↗
PubMed2003

[Study on separation of sulfonamides by capillary high-performance liquid chromatography and electrochromatography].

AIM: To establish separation methods of five sulfonamides by using capillary high performance liquid chromatography(mu-HPLC) and electrochromatography. The effect of mobile phase varies such as methanol content, pH, buffer solution concentration and voltage on their chromatographic behavior and electroosmesis flow was investigated. Capillary electrochromatography (CEC) was compared with mu-HPLC at the same condition. METHODS: Stationary phase was ODS, mobile phase was methanol and 2 mmol.L-1 H3PO4 buffer solution (pH 3.0-7.0), voltage was 0- -15 kV, flow rate was 10 microL.min-1, pressure was approximately 70 MPa and UV detection wavelength was 254 nm. RESULTS: Separations on base line have been respectively accomplished for five sulfonamides by mu-HPLC with mobile phase of methanol-2 mmol.L-1 H3PO4 buffer solution (30:70) at pH 5.0 in 67 min, and CEC with the same mobile phase at -5 kV voltage in 25 min. CONCLUSION: Electroosmesis flow of CEC decreased with the increase in methanol content, buffer solution concentration, increased with the increase in voltage and increase slightly with the increase in pH of mobile phase. Retention values (k) of solutes to be examined decreased with increasing methanol content of mobile phase in mu-HPLC and CEC. Retention values (k) of solutes increased slightly with increasing buffer solution concentration, decreased with increasing voltage in CEC. Trimethoprim(TMP) decreased obviously with increasing voltage in CEC. The effect of pH of mobile phase on retention values (k) was more complex. Five sulfonamides were separated at the same mobile phase condition by mu-HPLC and CEC. And separation speed of CEC was much faster than that of mu-HPLC. CEC was very fit for rapid separation of sulfonamides.

Anti-Infective Agents↗
PubMed2003

[Separation of salicylic acid drugs by aqueous and nonaqueous capillary electrophoresis with conductance detector].

AIM: To develop a method for separating salicylic acid drugs by aqueous and nonaqueous capillary electrophoresis with conductance detector. METHODS: Fused-silica capillary (55 cm x 50 microns ID) was used. The effects of concentration and pH of the running buffer, running voltage and injection time were studied. Salicylic acid (SA), acetylsalicylic acid (ASA) and sulfosalicylic acid (SSA) can be separated in a 10 mmol.L-1 Tris-30 mmol.L-1 H3BO3 buffer (pH 8.0), the separation voltage and injection time were 24 kV and 10 s, respectively. But tailing peaks appeared. In order to improve the separation efficiency and the sensitivity, ethanol was used as nonaqueous solvent. RESULTS: High sensitivity and resolution for SA, ASA and SSA were obtained in ethanol media, and there was excellent linearity between peak area and concentration of the analytes in the concentration range of 0.05-100 mg.L-1, 5.0-250 mg.L-1 and 0.08-100 mg.L-1 for SA, ASA and SSA, respectively. All the correlation coefficients were over 0.995. CONCLUSION: The analysis of SA and ASA in aspirin tablets was tried and good results were obtained in ethanol media. There was higher sensitivity and separation efficiency than in aqueous media.

Aspirin↗
PubMed2003

Separation-induced receptor changes in the hippocampus and amygdala of Octodon degus: influence of maternal vocalizations.

Relatively little is known about the basic mechanisms that play a role in the vulnerability of the developing brain toward adverse environmental influences. Our study in the South American rodent Octodon degus revealed that repeated brief separation from the parents and exposure to an unfamiliar environment induces in the hippocampal formation of male and female pups an upregulation of D1 and 5-HT1A receptor density in the stratum radiatum and stratum lacunosum moleculare of the CA1 region. In the CA3 region, only the 5-HT1A receptors were upregulated; no changes were observed for D1 receptors in this region. GABA(A) receptor density in the hippocampus and amygdala was downregulated (nonsignificant trend) after parental separation. The acoustic presence of the mother during parental separation suppressed the D1 and 5-HT1A receptor upregulation in some regions of the hippocampus; no such suppressing influence was observed for the GABA(A) receptors. In the basomedial amygdala, the maternal calls enhanced the separation-induced 5-HT1A receptor upregulation in the male pups, whereas in the female pups the separation-induced receptor densities were not only suppressed by the maternal call but further downregulated, compared with the control group. These results demonstrate that early adverse emotional experience alters aminergic function within the hippocampus and amygdala and that the mother's voice, a powerful emotional signal, can modulate these effects in the developing limbic system.

Acoustic Stimulation↗
PubMed2003

Optimization of the separation of organic explosives by capillary electrophoresis with artificial neural networks.

The separation of 12 explosives by capillary electrophoresis was optimized with the aid of artificial neural networks (ANNs). The selectivity of the separation was manipulated by varying the concentration of sodium dodecyl sulfate (SDS) and the pH of the electrolyte, while maintaining the buffer concentration at 10 mM borate. The concentration of SDS and the electrolyte pH were used as input variables and the mobility of the explosives were used as output variables for the ANN. In total, eight experiments were performed based on a factorial design to train a variety of artificial neural network architectures. A further three experiments were required to train ANN architectures to adequately model the experimental space. A product resolution response surface was constructed based on the predicted mobilities of the best performing ANN. This response surface pointed to two optima; pH 9.0-9.1 and 60-65 mM SDS, and pH 8.4-8.6 and 50-60 mM SDS. Separation of all 12 explosives was achieved at the second optimum. The separation was further improved by changing the capillary to an extended cell detection window and reducing the diameter of the capillary from 75 microm to 50 microm. This provided a more efficient separation without compromising detection sensitivity.

Aniline Compounds↗
PubMed1992

[The evolution of child custody after the separation of the parents].

Following the separation of spouses, a family undergoes a reorganization process where the choice of a formula for child custody represents a major step, which child's living environment will depend on. Despite the importance of this form of custody, it seems, in the context of the crisis following separation, that decisions surrounding that choice are often taken haphazardly, without much consideration of various alternatives. On a different note, the family's profile at the time of the separation is bound to change following the pace of the child's and the parent's development. What may seem a relevant formula for a three year-old child may not necessarily be the case when the child turns eight. This article looks at the extent to which the child custody formula evolves to adjust itself to the changing needs of children and parents. Research focused on a sampling of 112 families separated for an average of four and a quarter years, with children aged 10 (N = 49) or adolescents of 15 years of age (N = 63). Data was compiled through a telephone questionnaire filled out by the parent who was the most committed to the child's custody. The description of the two categories of change (minor and major) was made according to the original child custody formula, the time lapse since the separation, the child's age and parental re-composition. Results point to three main trends: a) child custody arrangements do not evolve much over time; b) when there are changes, these are especially motivated by the needs of the parents; and c) the changes mainly result in reducing the frequency of contacts between the child and the parent without custody.

Adolescent↗
PubMed2004

Separation of Siamese twins in Bratislava.

At the pediatric surgical clinic in Bratislava, in the year 2000, we successfully carried out the separation of Siamese twins, which we classified as "ischiopagus tetrapus"+. The pelvic ring, the gastrointestinal tract and the urogenital system were all malformed. There was a common terminal ileum and only a short segment of the large intestine with a blind end. This was a case of non-developed anal segment and rectum. Each of the twins had two kidneys and two commonly shared urinary bladders. There were two uteruses, which were both bicornuate in nature with a fallopian tube arising from each of the horns as well as an ovary. The orifices of both urinary bladders and those of the two uteruses joined into a common urogenital sinus. The external ostia of this sinus represented a bizarre fissure with a single skin fold similar to the labium majus, located dorsally at the point of fusion of the pelvic structures. The act of separation was performed in two stages. Separation of the gastrointestinal tract was urgent due to the severe ileus caused by aplasia of the anus and the rectum. This first stage procedure was performed on the third day of admission (24.2.2000) after the babies had spent a month in other health institutions. The definitive separation was carried out a month after the first procedure (28.3.2000) following the optimal stabilization of the functions of the gastrointestinal tract. The uropoietic and genital systems were separated. A new pelvic ring and a pelvic floor were formed. The anterior abdominal wall was reconstructed and plastic correction of the skin in the gluteal and perineal regions was performed. The colostomies are functioning well and the twins pass well-formed stools. Lucia has long dry intervals between mictions. Andrea has shorter dry intervals. The girls have recently celebrated their third birthday. Their mental development is excellent; they speak Slovak and Hungarian languages. They have a well-developed locomotive apparatus, without any movement impairments. (Tab. 1, Fig. 16, Ref. 10.)

Female↗
PubMed2004

[Optimization of the separation conditions of fingerprint for Rhubarb by high performance liquid chromatography].

OBJECTIVE: To optimize the separation conditions of fingerprint for Rhubarb by high performance liquid chromatography and lay the foundation of studies on its fingerprint by high performance liquid chromatography. METHODS: The reversed-phase high performance liquid chromatographic method was adopted. The samples were extracted by ultrasound and separated by a linear gradient elution on Shim-pack CLC-ODS column (6.0 mm i.d. x 150 mm, 5 microm), and then, with the methanol-1 ml/L phosphoric acid solution as mobile phase, were detected at UV 254 nm and column temperature 40 degrees C. During the linear gradient elution program, the volume fraction of methanol in mobile phase changed as follows: 0 min-5 min, 20%; 5 min-25 min, from 20% to 50%; 25 min-35 min, from 50% to 80%; 35 min-60 min, from 80% to 90%; 60 min-70 min, 90%. The flow rate was 0.8 ml/min from 0 min to 35 min, 0.6 ml/min from 35 min to 50 min and 1.0 ml/min after 50 min. RESULTS: The separation conditions described above achieved good result in the aspects of separable effect, stability, sensitivity, and reproducibility. CONCLUSION: The optimum separation conditions of fingerprint would be useful for establishing the method of fingerprint for Rhubarb by high performance liquid chromatography.

Chromatography, High Pressure Liquid↗
PubMed2004

[Management of intracanal separated instruments with the microsonic technique and its clinical outcome].

OBJECTIVE: To evaluate the clinical effect of microsonic technique on removal of intracanal separated instruments. METHODS: Forty-four teeth with 47 intracanal separated instruments, which could not be successfully managed by conventional methods, were endodontically treated with ultrasonic instruments under dental operating microscope. The success rate was calculated and the cases were reviewed 5 to 19 months after retreatment. RESULTS: Thirty-four (34/47) separated instruments in 33 (33/44) teeth were completely removed with a success rate of 75%. Thirteen separated instruments in 11 teeth, however, could not be eliminated from the canals. Root canal perforation or vertical fracture was not found. None of these teeth showed periapical deterioration in the follow-up. CONCLUSIONS: The combined use of dental operating microscope and ultrasonic instruments in endodontic treatment enriched the way of managing complicated cases of intracanal separated instruments.

Adult↗
PubMedDate not supplied

Optimization of enantiomeric separations in capillary electrophoresis by applying a design of experiments approach.

During early-phase pharmaceutical development, it is important to find an initial separation of enantiomeric compounds quickly in order to determine the enantiomeric purity of chiral drug substances. Highly selective screening methods are necessary to analyze the products to discover a satisfactory separation of the enantiomeric compounds. A screening approach based on the use of mixtures of multiple cyclodextrins in chiral capillary electrophoresis was employed to find the initial separation of chiral compounds. In a later phase of development, these complex methods need to be simplified for transferability. This study describes the simplification of the complex mixture of cyclodextrins into a single or dual system of only the enantioselective cyclodextrins. This was achieved by applying fractional factorial experimental designs to select the cyclodextrins that were responsible for the enantiomeric separation and response surface modeling designs for the optimization of the separation. In order to obtain robust methods, the concentration of the chiral selector, together with other important electrophoretic method parameters such as the concentration of the background electrolyte, pH, and run voltage, were optimized by employing a Box-Behnken experimental design.

Algorithms↗
PubMed2004

Separation and quantification of viral double-stranded RNA fragments by capillary electrophoresis in hydroxyethylcellulose polymer solutions.

Capillary electrophoresis (CE) is an analytical technique widely utilized to resolve complex mixtures of nucleic acids. CE uses a variety of polymers in solution that act as a molecular sieve to separate nucleic acid fragments according to size. It has been shown previously that purified dsDNA can be resolved efficiently by solutions of hydroxyethylcellulose (HEC) polymer, providing a rapid and high resolution method of separation. We have applied this separation technique to viral double-stranded (ds) RNA segments derived from rotavirus process samples. HEC polymers of various molecular masses and concentrations were identified and compared for their ability to separate dsRNA based on the extent of expected polymer network formation. The HEC polymer exhibiting the most desirable separation characteristics was then used for subsequent optimization of various method parameters, such as, injection time, electric field strength, dye concentration and capillary equilibration. The optimized method was then applied to the quantification of genome concentration based on a representative segment of the rotavirus genome. This study demonstrated that purified viral dsRNA material of known concentration could be used to generate an external standard curve relating concentration to peak area. This standard curve was used to determine the concentration of unknown samples by interpolation. This novel RNA quantification assay is likely to be applicable to other types of virus, including those containing dsDNA.

Cellulose↗
PubMed1997

[Separation of flavonol isomers by packed column supercritical fluids chromatography].

Flavonol isomers, which differ only in the position of hydroxyl group substitute on their chemical structures, showed different chromatographic behaviors. These polar compounds, in general, can be analyzed by high performance liquid chromatography. In this paper, the separation of flavonol isomers by home-set up packed column supercritical fluid chromatograph with carbon dioxide modified by ethanol containing 0.5% (V/V) phosphoric acid as mobile phase is described. The effects of temperature, pressure, composition of mobile phase and packed column type on the separation were studid. The addition of phosphoric acid to the mobile phase, which can not result in corrosion on the chromatographic system, enabled flavonol to elute from the column, and showed that the composition of the mobile phase was the most pronounced factor influencing the separation. Three columns were evaluated for the separation. It showed that the phenyl-bonded silica column was the best and the ODS column was the worst for the isomers separation. Increasing pressure shortened the retention time of each compound with good resolution, and higher temperature led to longer retention time.

Chromatography, Supercritical Fluid↗
PubMed2005

Capillary electrophoretic separation of enantiomers of amino acids and amino acid derivatives using crown ether and cyclodextrin.

The capillary zone electrophoresis using (+)-18-crown-6-tetracarbonic acid as a chiral selector was a suitable method for the enantiomeric separation of racemates of amino acids and of some amino acid derivatives (esters, dipeptides). The influence of the chemical structure of the compounds on the separation was investigated. After optimization of the separation conditions, baseline separations were obtained for most racemates. The addition of acetonitrile and TBAB yielded an improvement of the separation. Improved selectivity was further observed by the application of a cyclodextrin, HP-beta-CD, in combination with the crown ether.

Amino Acids↗
PubMed2005

[Application in capillary electrophoresis-based two-dimensional separation system].

An on-column, etched fused-silica porous junction interface was designed and fabricated, and an integrated two-dimensional separation platform involving on-line coupling of capillary isoelectric focusing (CIEF) with capillary electrophoresis (CE) was constructed by the interface. The primary advantages of this novel porous junction interface over previous designs are no dead volume, simplicity, ruggedness and convenience of column switching. This interface is particularly well suited for on-line coupling of CE-based multiple dimensional separation system. The feasibility and performance of the 2D CIEF-CE system constructed by such an etched porous junction were evaluated by the separation of soluble extracts of an antler. The results indicated that the total separation time was less than 1 h, and the 2D CE separation system was found to increase the resolving power and overall peak capacity over single dimension mode.

Animals↗
PubMed1992

ON- and OFF-pathways form separate neural substrates for motion perception: psychophysical evidence.

We have tested the hypothesis that in humans the signals carried by ON- and OFF-pathway respectively are processed for the perception of motion by two distinct physiological substrates. In vertebrates, onset of a bright visual stimulus is signaled to the CNS by ON-center retinal ganglion cells; onset of a dark stimulus is transmitted by OFF-center cells. We chose apparent motion generated by successive presentation of two adjacent lines as a stimulus. Lines presented on a bright background were either darker or brighter than this background. Delayed onset of a pair of bright or dark lines elicits apparent motion at the same time fulfilling the constraint of stimulating either ON- or OFF-center ganglion cells, respectively. We determined the threshold delay needed for subjects to perceive the temporal order of the onset of the two lines for various angular separations. The threshold delay for a pair of bright lines stayed low for separations from 2' to 7'. The threshold delay for a pair of dark lines was low only within a narrow range of separations centered around 3'. The variation of thresholds with line distance must reflect the existence of a limited processing zone for the perception of motion. The diameter of the processing zone for bright lines is about twice as large as that for dark lines. This suggests that in humans the separation of ON- and OFF-pathways extends to the early stages of motion perception. To test this hypothesis independently, thresholds were determined when a bright and a dark line were presented in succession. This was done for a separation of 3' where thresholds for a pair of lines with equal contrast are similarly low. Temporal order was perceived correctly only when the delay was at least two to four times as high as the threshold delays found for the equal contrast stimuli.

Humans↗
PubMed2005

Enhancement of oxygen transfer and nitrogen removal in a membrane separation bioreactor for domestic wastewater treatment.

Biological nitrogen removal in a membrane separation bioreactor developed for on-site domestic wastewater treatment was investigated. The bioreactor employed hollow fiber membrane modules for solid-liquid separation so that the biomass could be completely retained within the system. Intermittent aeration was supplied with 90 minutes on and off cycle to achieve nitrification and denitrification reaction for nitrogen removal. High COD and nitrogen removal of more than 90% were achieved under a moderate temperature of 25 degrees C. As the temperature was stepwise decreased from 25 to 5 degrees C, COD removal in the system could be constantly maintained while nitrogen removal was deteriorated. Nevertheless, increasing aeration supply could enhance nitrification at low temperature with benefit from complete retention of nitrifying bacteria within the system by membrane separation. At low operating temperature range of 5 degrees C, nitrogen removal could be recovered to more than 85%. A mathematical model considering diffusion resistance of limiting substrate into the bio-particle is applied to describe nitrogen removal in a membrane separation bioreactor. The simulation suggested that limitation of the oxygen supply was the major cause of inhibition of nitrification during temperature decrease. Nevertheless, increasing aeration could promote oxygen diffusion into the bio-particle. Sufficient oxygen was supplied to the nitrifying bacteria and the nitrification could proceed. In the membrane separation bioreactor, biomass concentration under low temperature operation was allowed to increase by 2-3 times of that of moderate temperature to compensate for the loss of bacterial activities so that the temperature effect was masked.

Biomass↗
PubMed2005

[Preparation of vancomycin chiral stationary phase and study of racemate separation].

By adopting the bifunctional group reagent methylene-di-paraphenylene iso-cyanate (MDI), a ring antibiotic chiral stationary phase (CSP) was prepared in non-aqueous dimethylfomamide (DMF) with vancomycin which is a macrocyclic glycopeptide antibiotics bonded on gamma-amidopropyl silica gel. It was used in the chiral separation in high performance liquid chromatography. The results showed that vancomycin CSP synthesized in this way can be well used in enantiomer separation of the chiral compounds in normal and reversed-phase. It can be confirmed that the separation capability in reversed-phase is better than that in normal phase. Seventeen pairs of enantiomers were separated in reversed-phase mode, and the results showed a wide range of application. The phosphorus buffer system was better than the triethylamineacetic acid buffer system. The resolution of some chiral drugs such as D,L-dansyl amino acid has certain rule, and provides information about absolute configuration. The aging or denaturalization can not happen in the CSP when phase system was transformed, so it has some stability. The mechanism of the separation was analyzed and found to be the same as that of Armstrong.

Anti-Bacterial Agents↗