Retention Times

Top PDF Retention Times:

Seed retention times in the New Zealand pigeon, Hemiphaga novaeseelandiae

Seed retention times in the New Zealand pigeon, Hemiphaga novaeseelandiae

offered to 10 pigeons, although only five pigeons in total (two males, two females and one of unknown sex) actually ingested fruits. Twenty fruits of a single species were placed in the usual feeding tray in the aviary in the morning before normal food was made available. We recorded the times at which fruits were eaten and the number of fruits eaten. Any fruits not consumed within 10 min of the first fruit being swallowed were removed in order to keep the range of ingestion times small for seeds in one feeding bout, and the normal food supply was placed in the feeding tray. We observed pigeons continuously until all seeds were recovered, recording the time of each defecation and the number of seeds defecated. We use the term ‘seed retention’ to encompass both seeds that were defecated and those that were regurgitated. ‘Seed passage’ refers only to those seeds that were defecated. We calculated seed retention times by subtracting the midpoint of the time between ingestion of the first and last fruits from the time of egestion.

6 Read more

LC AND LC-MS STUDY ON STRESS DECOMPOSITION BEHAVIOR OF PACLITAXEL AND ESTABLISHMENT OF VALIDATED STABILITY-INDICATING ASSAY METHOD

LC AND LC-MS STUDY ON STRESS DECOMPOSITION BEHAVIOR OF PACLITAXEL AND ESTABLISHMENT OF VALIDATED STABILITY-INDICATING ASSAY METHOD

A number of light induced degradants were observed. From a stability perspective, the largest and most interesting degradant corresponded to the 14.8 min peak which had a molecular mass identical to Paclitaxel (MW 853). Other lower level photodegradants observed in this profile included a second early eluting Paclitaxel isomer at 9.9min and three isomers of Paclitaxel minus a core carbonyl at retention times of 27.8, 30.2, and 36.4min. The product ion spectra of each of the photodegradants observed indicated a modification of the Paclitaxel core. The MS–MS product ion spectrum of the 14.8 min Paclitaxel isomer is shown in Fig. 10. Examination of the product ion spectrum of this primary photo degradant indicates the same diagnostic product ions indicative of the Paclitaxel side chain at m/z 286, 268, and 240 are present. In addition, the product ion at m/z 509, indicative of the deacetylated core, is also present. The absence of the product ion at m/z 569 indicates facile loss of a single molecule of acetic acid is favored for this Paclitaxel isomer. This is also consistent with the observation of a new product ion at m/z 794 corresponding to loss of acetic acid from the

9 Read more

DEVELOPMENT AND VALIDATION OF REVERSE-PHASE HPLC METHOD FOR ESTIMATION OF KETOCONAZOLE IN BULK DRUG

DEVELOPMENT AND VALIDATION OF REVERSE-PHASE HPLC METHOD FOR ESTIMATION OF KETOCONAZOLE IN BULK DRUG

A simple, accurate rapid and precise RP-HPLC method has been developed and validated for determination of ketoconazole in bulk drug. The RP-HPLC separation was achieved on Promosil C-18, (250 mm, 4.6 mm, 5µm) using mobile phase water : acetonitrile : buffer ph 6.8 (51:45:4 v/v) at flow rate of 1.0 ml/min at ambient temperature. The retention times were 2.713 min. for ketoconazole. Calibration plots were linear over the concentration range 1-50µg/ml. Quantification was achieved with photodiode array detection at 238 nm over the concentration range of 1-50 µg/ml. The method was validated statistically and applied successfully for the determination of ketoconazole. Validation studies revealed that method is specific, rapid, reliable, and reproducible. The high recovery and low relative standard deviation confirm the suitability of the method for the routine determination of ketoconazole in bulk drug.

7 Read more

GC Determination of Fatty Acids in Fish Supplements

GC Determination of Fatty Acids in Fish Supplements

In the current study in the analyzed food supplements, the peaks of the methylated fatty acids were identified by the retention times by comparison with the available reference standards including: methyl esters of Palmitic acid, Palmitoleic acid, Stearic acid, Oleic acid, Linoleic acid, and Linolenic acid. The quantitative analysis of the compounds was accomplished by the comparison of the chromatographic peak areas of the components of the test sample with the comparative reference standard, having a known quantity, by applying the methods of the external standard or the internal standard, and the application of the method of the assessment of the relative values of the chromatographic peak areas of analytes to the sum of the areas in all of the components of the analyzed sample, when they all were exhibited in the chromatogram, and their analytical signals were comparable in intensity.

13 Read more

RP-HPLC method development and validation for simultaneous estimation of nebivolol and valsartan in pharmaceutical dosage forms

RP-HPLC method development and validation for simultaneous estimation of nebivolol and valsartan in pharmaceutical dosage forms

A simple, Accurate, precise method was developed for the simultaneous estimation of the Nebivolol and Mobile phase containing Buffer 0.1%OPA: Acetonitrile taken in the ratio 55:45 was pumped through column at a flow rate of 1 ml/min. Buffer used in this method was 0.1% OPA buffer. Temperature was maintained at 30°C. Optimized wavelength selected was 260.0 nm. Retention time of Nebivolol and Valsartan were found to 2.227 min and 3.126 %RSD of the Nebivolol and Valsartan were and found to be 0.6 and 0.4 respectively. %Recovery was obtained as 99.94% and 100.02% for Nebivolol and Valsartan respectively. LOD, LOQ values obtained from regression equations of Nebivolol and Valsartan were 0.05, 0.16 and 0.18, 0.53 respectively. Regression equation of Nebivolol is y=10542.x+470.4, y = 13049x+16927 of Valsartan. Retention times were decreased and that run time was decreased, so the method developed was simple and economical that can be adopted in regular Quality control test in Industries. Retention times were decreased and run time was decreased, so the method developed was simple and economical that can be adopted in regular Quality control test in Industries.

8 Read more

Rapid method development in ion chromatography using quantitative structure retention relationships

Rapid method development in ion chromatography using quantitative structure retention relationships

Tyteca et al. [15] have proposed the retention factor ratio (or k-ratio) as a chromatographic similarity index, where clustered compounds based on a selected k- ratio threshold value are used for modelling. In other words, to create a cluster that could be used as a training set to form a model for the target compound, only compounds having absolute k-ratio values lower than a threshold value were included in the training set to generate a partial least squares (PLS) model. This approach resulted in low prediction errors (mean absolute error (MAE) <1 min) for the three liquid chromatography modes (HILIC, RPLC and IC), which is a sufficient level of accuracy for "scoping" method development. However, the k-ratio-based-clustering approach has a limitation in that when a new target compound is used it is not possible to identify the training set with most similar retention times due to the lack of a priori retention information for the target compound. Thus, a dual filter approach, combining the structural Tanimoto similarity (TS)-based-filter with the k-ratio filter, was also investigated using the HILIC and RPLC datasets [15]. Unfortunately, the employed dual filter approach did not improve predictions in HILIC and RPLC, presumably because the TS filter (used as the first filter) did not adequately reflect the chromatographic similarity of the compounds, possibly due to the complex mechanisms at play in HILIC and RPLC [15].

213 Read more

Electrophoretic migration of organophosphorus pesticides as a function of separation potential in micellar electrokinetic chromatography : a basis of predicting the retention factors

Electrophoretic migration of organophosphorus pesticides as a function of separation potential in micellar electrokinetic chromatography : a basis of predicting the retention factors

Abstract. Retention factors (k ′ ) in Micellar Electrokinetic Chromatography (MEKC) are very often calculated against the mobility of fully retained hydrophobic micelle markers, which are not abundant for universal use. An alternative approach was proposed to predict the k ′ values on the basis of a functional relationship between the solutes retention times and separation potentials using organophosphorus pesticides (OPPs) as reference hydrophobic compounds. The use of the proposed simple linear model was evaluated for another set of hydrophilic OPPs and its practicality was defined.

9 Read more

Estimation and evaluation of the effect of pH on ciprofloxacin in drug formulations

Estimation and evaluation of the effect of pH on ciprofloxacin in drug formulations

Another line diagram to offer the graphical representation depicting average or mean values of peak retention times in chromatograms (Presented in Appendences), a qualitative parameter has also been drawn by which one can easily understand the effect of pH treatments over different treatment in terms of qualitative identification or degeneration of the drug substance ciprofloxacin in samples. The graph (figure 2) is presented below.

7 Read more

PROFILING THE SECONDARY CHEMICAL CLASS OF IN VIVO MELIA COMPOSITA WILLD  LEAF USING ETHANOLIC FRACTION

PROFILING THE SECONDARY CHEMICAL CLASS OF IN VIVO MELIA COMPOSITA WILLD LEAF USING ETHANOLIC FRACTION

For the widespread acceptance of herbal medicines, standardization, quality control of the herbal materials, as well as evaluation of efficacy, safety and quality of the phytopharmaceutical are indispensable. [8] Identification of individual components of complex mixtures of phytochemicals requires the use of several techniques. One of the most popular methods of studying phytochemical composition is GC-MS, which allows the identification of the specific natural compounds found in a plant extracts by comparing their relative retention times and indices and their mass spectra. [9],[11]

10 Read more

Development and Validation of Analytical Method for Simultaneous Estimation of Cefixime and 
      Ofloxacin in Bulk and Tablet Dosage Form by RP-HPLC Method

Development and Validation of Analytical Method for Simultaneous Estimation of Cefixime and Ofloxacin in Bulk and Tablet Dosage Form by RP-HPLC Method

Accepted: 29 Dec 2014 The objective of present work was to develop and validate a simple, accurate,precise HPLC method for the estimation of cefixime and ofloxacin. The chromatographic separation was achieved on a Hypersil BDSC18 column (4.6x250 mm,5µmparticlesize). Different mobile phase systems in different proportions were tried. For HPLC method a mobile phase consisting of Methanol and Water (70:30) produced symmetric peak shape with good resolution for both the drugs. Next, the drugs were chromatographed under different flow rates from which a flow rate of 1.0 ml/min was selected. The retention times of cefixime and ofloxacin were found to be 2.96 min and 4.15 min, respectively.The proposed method was found to have excellent linearity in the concentration range of 20- 80mg/ml with correlation coefficient r2=0.999 and 0.999 for cefixime and ofloxacin repectively.The method was validated for linearity, precision, LOD, LOQ and robustness.The proposed method optimized and validated as per ICH guidelines.

6 Read more

Comparative study of organic solvent and water-soluble lipophilic extractives from wheat straw I: yield and chemical composition

Comparative study of organic solvent and water-soluble lipophilic extractives from wheat straw I: yield and chemical composition

A capillary column with thin films was used for the GC analyses. It was found that the column was able to separate all classes of extractives and individual compounds. Identifi- cation of the components was based on a comparison of their retention times or mass spectra with authentic com- pounds by mass fragmentography (5970 Series, Hewlett Packard) (data not shown) or with library spectra. Equal amounts of the standards gave peak areas in ratios of 1.00 : 0.88 : 0.86 : 0.93 : 0.85 : 0.74 : 1.00 : 0.78 : 0.60 for fatty acid, azelaic acid/maleic acid, resin acid, sterol, wax, steryl ester, monoglyceride, diglyceride, and triglyceride, respectively. The ratios were reproducible and were not notably affected by small variations in injection, detector temperature, in- jection volume, or carrier gas flow. The use of these nine appropriate standards compensates for some of the discrimi- nation possibly occurring with GC analysis and provides a control measure within each chromatogram. The FID re- sponse was assumed to be the same for the component group and the corresponding standard. In other words, the indi- vidual peak area of each fatty acid, azelaic acid or maleic acid, resin acid, sterol, wax, steryl ester, monoglyceride, diglyceride, and triglyceride in samples was divided by 1.00, 0.88, 0.86, 0.93, 0.85, 0.74, 1.00, 0.78, and 0.60, respectively, before calculating their concentrations in the samples.

6 Read more

Volatilizable Biogenic Organic Compounds (VBOCs) with two dimensional Gas Chromatography-Time of Flight Mass Spectrometry (GC GC-TOFMS): sampling methods, VBOC complexity, and chromatographic retention data

Volatilizable Biogenic Organic Compounds (VBOCs) with two dimensional Gas Chromatography-Time of Flight Mass Spectrometry (GC GC-TOFMS): sampling methods, VBOC complexity, and chromatographic retention data

The peaks for 18 of the 21 standard compounds met the PSC and were positively identified based on their chromatographic retention times and mass spectra (Ta- ble S4, Supplement); the peak for one additional stan- dard compound was positively identified based on its mass spectral and retention time data, though was too small to meet the PSC. The 18 compounds included all 10 of the PSC-satisfying standard compounds found in the Fig. 4 chromatogram. In Fig. 5, the number of ten- tatively identified peaks meeting the PSC totaled 312 (Table S4, Supplement). Compared to the Fig. 4 chromatogram, the Fig. 5 chromatogram evidenced the presence of the following numbers of additional com- pounds: six monoterpenes; 30 oxygenated monoter- penes; 26 sesquiterpenes; 10 oxygenated sesquiter- penes. As compelling evidence of the complexity of the VBOC group, among the 312 tentative identifica- tions, there are nine examples of multiple peaks match- ing well as the same compound: (1) four peaks as E,E-2,6-dimethyl-1,3,5,7-octatetraene; (2) two peaks as 3-methyl-undecane; (3) two peaks as γ -terpinene; (4) three peaks as d-verbenol; (5) two peaks as trans- 1-methyl-4-(1-methylethly)-2-cyclohexen-1-ol; (6) two peaks as β-cubebene; (7) two peaks as germacrene D; (8) two peaks as longipinocarvone; and (9) four peaks as caryophyllene oxide.

17 Read more

LC-MS/MS Based Metabolomics to Identify Biomarkers Unique to Laetiporus sulphureus

LC-MS/MS Based Metabolomics to Identify Biomarkers Unique to Laetiporus sulphureus

Abstract: LC/MS/MS technique, employing QTOF mass analyzer, was used for comparative metabolomic fingerprinting of seven edible mushroom varieties (P.ostreatus, L.edodes, L.sulphureus, A.campestris, T.clypeatus, T.microcarpus and T.letestui). The aim was to identify biomarkers unique to L.sulphureus which might be responsible for the pharmacological claim of the mushroom by the Kaffa people in Ethiopia. As an outcome of the data mining and pre-treatment step using Markerview TM software, positive and negative ionization data matrices of 71,083 and 54,856 peaks, respectively, were obtained. Regardless of the ionization mode, the principal component analysis (PCA) of the data set representing the seven edible mushrooms each in triplicate revealed a unique separate clusters for L.sulphureus, documenting differences in LC-MS profiles associated with the sample. Based on plot profile, only 14 and 27 peaks representing monoisotopic ions unique to L.sulphureus at the positive and negative ionization mode respectively were obtained. All the pre-selected biomarkers were searched from METLIN metabolite database, but only one peak at 13.41 min with m/z of 471.3468 and 469.3348, positive and negative ionization, respectively were tentatively identified as 18α-glycyrrhetinic acid (commonly called Enoxolone). This metabolite was verified by comparing the retention time, MS and MS/MS data spectra of authentic standard and sample obtained from Peakview TM software. Mass frontier software was used to generate possible fragmentation and rearrangement mechanisms of the parent ion. In conclusion, 18α-glycyrrhetinic acid might be one of the compounds responsible for the biological claim of the local people.

13 Read more

Effect of Biscuit Baking Conditions on the Stability of Microencapsulated 5 Methyltetrahydrofolic Acid and Their Physical Properties

Effect of Biscuit Baking Conditions on the Stability of Microencapsulated 5 Methyltetrahydrofolic Acid and Their Physical Properties

cuits, which is baked at higher temperature, is caused by Maillard reaction. The golden brown color in biscuits turned to intense red and dark when baked for short times at 200˚C and 220˚C (Table 4). This is in agreement with previous report that showed an increase in oven tem- perature decreases the lightness of biscuit, independent of heat transfer mode of oven temperature to the product (>190˚C) [27]. Further heating time, such as 9 and 12 min at 200˚C and 220˚C led to almost charring of the biscuit surface.

8 Read more

Application of Cationic Tapioca to Unmodified Pearl Corn Starch – A Papermaking Handsheet Study

Application of Cationic Tapioca to Unmodified Pearl Corn Starch – A Papermaking Handsheet Study

While strength analyzation was the major purpose for conducting this experiment, other e also examined including drainage and retention of the starch in the sheets. Drainage was considered because too much starch could cause issues with drying of the sheet, if drainage is too slow, the CSF number will be low, and the sheet will not be dry ough by the time it reaches the dryers. This would require an increase of vacuum suction, thus an increase of energy usage and operational cost. Therefore, TAPPI CSF tests were computed with the addition of starch in the pulp. Retention of starch in the sheet is also a necessary factor to be tested because when the starch passes through the sheet it ends up in the process water, creating food for bacteria and increase in biological activity. Starch was added to pulp and filtered through a vacuum filtration up, then the water sucked through the sheet was analyzed through ash content to analyze the amount of starch that did not remain in the sheet.

7 Read more

Determination of Some Components of Balanites Aegyptiaca Oil by Chromatographic Methods

Determination of Some Components of Balanites Aegyptiaca Oil by Chromatographic Methods

The soap solution obtained after saponification was acidified with concentrated hydrochloric acid ( 36 % 10 mL ). The fatty acids generated were then extracted with petroleum ether three times ( 100 mL total ) . The fatty acids solution was washed several times with distilled water until free from acid ( neutral to methyl orange indicator). The ether was removed in vaccue (25-30°C ) . Preparation of fatty acid methyl ester 6

5 Read more

LC-ESI-MS profile, antioxidant activity and cytotoxic screening of Oligomeris linifolia (Vahl) Macbr. (Resedaceae)

LC-ESI-MS profile, antioxidant activity and cytotoxic screening of Oligomeris linifolia (Vahl) Macbr. (Resedaceae)

profile was as follows: 95% A (5 min), 95-90% A (10 min), 90- 50% A (55 min), 50-95% A (65 min), and 95% A (70 min). The injection volume was 10 μL. The flow rate (0.6 mL/min) was split 1:1 before the MS interface with negative ion mode parameters (source temperature 150 °C, desolvation temperature 350 °C, cone gas flow 50 L/h, cone voltage 50 eV, capillary voltage 3 kV, and desolvation gas flow 600 L/h). Spectra were recorded in the ESI negative mode between 50-1000 m/z. The peaks and spectra were processed using the Maslynx 4.1 software. The flavonoids isolated from O. linifolia in our previous study (Hussein et al., 2013), together with other pure flavonoids, obtained from Phytochemical and Plant Systematic Department, were used as reference samples. Known compounds were confirmed by comparing their retention times and mass spectra with standards. Unknowns were tentatively identified by comparing their mass fragmentation pattern with literatures.

5 Read more

ANALYTICAL METHOD DEVELOPMENT AND
VALIDATION FOR BRINZOLAMIDE AND TIMOLOL MALEATE IN API AND COMBINE PHARMACEUTICAL DOSAGE FORMS BY RP-HPLC.Pakir PranayaDOWNLOAD/VIEW

ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR BRINZOLAMIDE AND TIMOLOL MALEATE IN API AND COMBINE PHARMACEUTICAL DOSAGE FORMS BY RP-HPLC.Pakir PranayaDOWNLOAD/VIEW

A Standard solution of Brinzolamide and Temolol maleate working standard was prepared as per procedure and was injected five times into the HPLC system. The system suitability parameters were evaluated from standard Chromatograms obtained by calculating the % RSD of retention times, tailing factor, theoretical plates and peak areas from five replicate injections.

8 Read more

Chemical Compositions and Anticancer Potential of`Essential Oil from Greenhouse-cultivated Ocimum basilicum Leaves

Chemical Compositions and Anticancer Potential of`Essential Oil from Greenhouse-cultivated Ocimum basilicum Leaves

eucalyptol was further confirmed by co-chromatography with authentic standards (Sigma-Aldrich) under the same chromatographic conditions mentioned above. GC-FID analysis was also carried out to obtain qualitative complementary results to those obtained by GC-MS as well as to obtain quantitative measures of the identified compounds. GC-FID was carried out on a ThermoQuest gas chromatograph coupled to an FID detector equipped with a split-splitless injector (split ratio 1:30) and HP-5 capillary column (Crosslinked 5 % PH ME Silicone, 30 m×0.32 mm×0.25 μm film thickness). One microlitre aliquots were autoinjected into the GC-FID system and analyzed using the same linear temperature program applied in the GC- MS analysis above. The carrier gas was nitrogen (N 2 99.99 %) and the flow rate was 1 ml/min. Each sample was analyzed triplicate. Essential oil constituents were identified by calculating the linear retention index of each constituent relative to (C8-C20) n-alkanes mixture (which was analyzed separately by GC-FID using the same column) and applying Van Den Dool Eqn. [25] .

6 Read more

Potential Of Biomass Energy For Generation Of Electricity: Model For Small Rural Area Makori In District Karak Kpk And Comparison Of Power Generation From Sewage Sludge Of Makori Village With That Of Bara River In Peshawar

Potential Of Biomass Energy For Generation Of Electricity: Model For Small Rural Area Makori In District Karak Kpk And Comparison Of Power Generation From Sewage Sludge Of Makori Village With That Of Bara River In Peshawar

Waste obtained from living organisms, including plants and animals is known as Biomass. Energy derived from biomass can be used as a direct source of energy or by converting it into a fuel called as bio fuel. Renewable energy resources have become potential entrant for the achievement of future energy needs keeping in view the current energy requirement and the diminishing sources of fuel. Biomass, being a renewable energy source, is one of the most capable alternatives to the conventional energy resources including mineral oil and natural gas. To exploit biomass in more cost-effective and proficient way, research work is in progress all over the world. Pakistan being a developing country, where fulfillment of energy requirements is a big challenge; power generation using biomass can be useful in order to overcome the energy shortfalls. This paper describes power generation potential of the waste water of small rural area Makori in District Karak, KPK. It considers the possibility of bio gas run power plant near MOL Production facility. In order to analyze sewage sludge laboratory analysis was performed. Daily sewage sludge discharge data was recorded from the flow meter available at MOL Production facility. Biogas potential was calculated using 10, 20 and 30 days retention time. It was estimated that 261915 m3, 524474m3 and 605559m3 of methane can be produced in a year and the power production was estimated to be 91 kW, 182 kW and 210 kW respectively.

7 Read more

Show all 10000 documents...