Pub Date : 2015-04-27DOI: 10.2174/1874065001508010007
R. Kachave, M. Kale, R. Wagh
A rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method has been developed and fully validated for the determination of lansoprazole (LNZ) in human plasma. Pantaprazole was used as an internal standard (IS). Analytes and the internal standard were extracted from human plasma by solid-phase extraction technique using Oasis HLB, Oasis Max, Varian Bond Elute Plexa, Orochem cartridges. The reconstituted samples were chromatographed on a thermo hypurity Advance, 50 X 4.6mm, 5 µ by using acetonitrile and 2 mM ammonium acetate solution(80:20 v/v) as the mobile phase at a flow rate of 1.0 mL/min. Detection was carried out LC-MS/MS (API 3000) in negative ion mode. The calibration curves obtained were linear (R 2 -0.999) over the concentration range of 4.50- 2800.00 ng/ml for lansaprazole. The results of the intra- and inter-day precision studies were well within the acceptable limits. The overall average recoveries of analyte and IS were found to be 92.10-99.11%. The analyte were found to be stable of stability study. Developed and validated analytical method was found to be simple, rapid, specific, sensitive, precise and cost effective than reported methods. The method has been successfully applied to the investigation of a preclinical pharmacokinetic study with desired precision and accuracy along with high throughput.
{"title":"Development and Validation of a LC-MS/MS Method to DetermineLansoprazole in Human Plasma","authors":"R. Kachave, M. Kale, R. Wagh","doi":"10.2174/1874065001508010007","DOIUrl":"https://doi.org/10.2174/1874065001508010007","url":null,"abstract":"A rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method has been developed and fully validated for the determination of lansoprazole (LNZ) in human plasma. Pantaprazole was used as an internal standard (IS). Analytes and the internal standard were extracted from human plasma by solid-phase extraction technique using Oasis HLB, Oasis Max, Varian Bond Elute Plexa, Orochem cartridges. The reconstituted samples were chromatographed on a thermo hypurity Advance, 50 X 4.6mm, 5 µ by using acetonitrile and 2 mM ammonium acetate solution(80:20 v/v) as the mobile phase at a flow rate of 1.0 mL/min. Detection was carried out LC-MS/MS (API 3000) in negative ion mode. The calibration curves obtained were linear (R 2 -0.999) over the concentration range of 4.50- 2800.00 ng/ml for lansaprazole. The results of the intra- and inter-day precision studies were well within the acceptable limits. The overall average recoveries of analyte and IS were found to be 92.10-99.11%. The analyte were found to be stable of stability study. Developed and validated analytical method was found to be simple, rapid, specific, sensitive, precise and cost effective than reported methods. The method has been successfully applied to the investigation of a preclinical pharmacokinetic study with desired precision and accuracy along with high throughput.","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2015-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87545005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-03-31DOI: 10.2174/1874065001508010001
Ahmad M. El-Zinati, M. Abdel-Latif
A comparative study of the use of first derivative zero order crossing spectra for the resolution of Paracetamol and Tramadol hydrochloride in mixtures has been achieved showing the success of the first derivative method in resolving and quantifying both compounds. Using the first derivative, rather than the second derivative, results in improved signal to noise ratio. The absorption spectra of prepared mixtures were scanned in the range of 200-500 nm. The linear concentration ranges were 25-112 and 6-48 µg mL -1 for paracetamol and Tramadol hydrochloride, respectively. The method has been successfully used for prediction of concentrations of both compounds in mixtures with good selectivity, high sensitivity and extremely low relative error. Statistical comparison was performed using t-test at 95% confidence level. There was no significant statistical difference between the results obtained by the first derivative method and the accepted values for both compounds. Also, the percentage errors were very low which adds to the merits of our work in terms of both sensitivity and accuracy.
对一阶导数零阶交叉光谱在对乙酰氨基酚和盐酸曲马多混合物中分离的比较研究表明，一阶导数方法在分离和定量这两种化合物方面取得了成功。使用一阶导数，而不是二阶导数，可以提高信噪比。对制备的混合物在200 ~ 500 nm范围内的吸收光谱进行扫描。对乙酰氨基酚和盐酸曲马多的线性浓度范围分别为25 ~ 112和6 ~ 48µg mL -1。该方法具有选择性好、灵敏度高、相对误差极低的优点，成功地用于预测混合物中两种化合物的浓度。统计学比较采用95%置信水平的t检验。用一阶导数法得到的结果与两种化合物的公认值之间没有显著的统计学差异。此外，错误率非常低，这增加了我们的工作在灵敏度和准确性方面的优点。
{"title":"Simultaneous Determination of Paracetamol and Tramadol in PharmaceuticalTablets by Derivative UV-Vis Absorption Spectrophotometry","authors":"Ahmad M. El-Zinati, M. Abdel-Latif","doi":"10.2174/1874065001508010001","DOIUrl":"https://doi.org/10.2174/1874065001508010001","url":null,"abstract":"A comparative study of the use of first derivative zero order crossing spectra for the resolution of Paracetamol and Tramadol hydrochloride in mixtures has been achieved showing the success of the first derivative method in resolving and quantifying both compounds. Using the first derivative, rather than the second derivative, results in improved signal to noise ratio. The absorption spectra of prepared mixtures were scanned in the range of 200-500 nm. The linear concentration ranges were 25-112 and 6-48 µg mL -1 for paracetamol and Tramadol hydrochloride, respectively. The method has been successfully used for prediction of concentrations of both compounds in mixtures with good selectivity, high sensitivity and extremely low relative error. Statistical comparison was performed using t-test at 95% confidence level. There was no significant statistical difference between the results obtained by the first derivative method and the accepted values for both compounds. Also, the percentage errors were very low which adds to the merits of our work in terms of both sensitivity and accuracy.","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"24 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2015-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74632111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-10-14DOI: 10.2174/1874065001307010022
Y. Yoshimi
It is known that the diffusive permeability of solutes within a thin layer of molecularly imprinted polymer (MIP) may be affected by specific binding of the MIP with its template molecule. This phenomenon, termed the gate effect, shows promise for the development of novel biomimetic sensors. However, the mechanism underlying this effect is still unclear; although the relationship between the specific adsorption of a template and the corresponding porosity and permeability of the polymeric film or membrane is very important, this association has not yet been examined in detail. We therefore studied this relationship using a molecularly imprinted self-supporting membrane (MISSM) possessing chiral specificity, specially developed as a tool for investigating the gate effect. Both the diffusive permeability and volume porosity of the MISSM were sensitive to the presence of the template compounds (D and L-phenylalanine) at concentrations as low as 5 µM, while, at the same time, insensitive to the enantiomer of the template. The relationship between the amount of adsorbed template and the equilibrium template concentration followed the expected Langmuir isotherm pattern, which indicates the thermodynamic homogeneity of binding sites in the MISSM. This study also demonstrated that the relative concentration of the adsorbed template in the membrane was only 3 ppm and relative site occupation was only 1% following exposure to a 5 µM concentration of the template. These results show that the gate effect may be advantageously exploited during application of MIPs in amplifiers or sensors offering high sensitivity. Molecularly imprinted polymers (MIPs) are synthetic polymers that contain specific binding sites formed by imprinting of a target molecule (or template) during the polymerization process. An MIP layer can be prepared by a simple and economical procedure (1-3). Before such MIPs may be employed as molecular recognition elements in chemical-sensing devices, however, it is necessary to develop a means of translating specific binding events at the MIP into an electric signal. The so-called gate effect, which refers to changes in the diffusive permeability of solutes within the MIP layer resulting from specific binding at the template, can be used as a mechanism for signal transference based on conductometry, utilizing changes in the ionic permeability of the MIP membrane associated with a specific interaction with the template (4-6). In this gate analogy, the template corresponds to the key while the MIP site which allows specific rebinding with the template corresponds to the keyhole. An amperometric method is also applicable, using a thin MIP layer grafted onto an electrode, in which the template can be detected by following changes in the faradic current resulting from the change in permeability of a redox marker across the MIP layer (7-11). The gate effect is a selective process capable of discriminating between
{"title":"Changes in the Porosity and Permeability of a Molecularly Imprinted Membrane Induced by the Adsorption of a Trace Quantity of Template","authors":"Y. Yoshimi","doi":"10.2174/1874065001307010022","DOIUrl":"https://doi.org/10.2174/1874065001307010022","url":null,"abstract":"It is known that the diffusive permeability of solutes within a thin layer of molecularly imprinted polymer (MIP) may be affected by specific binding of the MIP with its template molecule. This phenomenon, termed the gate effect, shows promise for the development of novel biomimetic sensors. However, the mechanism underlying this effect is still unclear; although the relationship between the specific adsorption of a template and the corresponding porosity and permeability of the polymeric film or membrane is very important, this association has not yet been examined in detail. We therefore studied this relationship using a molecularly imprinted self-supporting membrane (MISSM) possessing chiral specificity, specially developed as a tool for investigating the gate effect. Both the diffusive permeability and volume porosity of the MISSM were sensitive to the presence of the template compounds (D and L-phenylalanine) at concentrations as low as 5 µM, while, at the same time, insensitive to the enantiomer of the template. The relationship between the amount of adsorbed template and the equilibrium template concentration followed the expected Langmuir isotherm pattern, which indicates the thermodynamic homogeneity of binding sites in the MISSM. This study also demonstrated that the relative concentration of the adsorbed template in the membrane was only 3 ppm and relative site occupation was only 1% following exposure to a 5 µM concentration of the template. These results show that the gate effect may be advantageously exploited during application of MIPs in amplifiers or sensors offering high sensitivity. Molecularly imprinted polymers (MIPs) are synthetic polymers that contain specific binding sites formed by imprinting of a target molecule (or template) during the polymerization process. An MIP layer can be prepared by a simple and economical procedure (1-3). Before such MIPs may be employed as molecular recognition elements in chemical-sensing devices, however, it is necessary to develop a means of translating specific binding events at the MIP into an electric signal. The so-called gate effect, which refers to changes in the diffusive permeability of solutes within the MIP layer resulting from specific binding at the template, can be used as a mechanism for signal transference based on conductometry, utilizing changes in the ionic permeability of the MIP membrane associated with a specific interaction with the template (4-6). In this gate analogy, the template corresponds to the key while the MIP site which allows specific rebinding with the template corresponds to the keyhole. An amperometric method is also applicable, using a thin MIP layer grafted onto an electrode, in which the template can be detected by following changes in the faradic current resulting from the change in permeability of a redox marker across the MIP layer (7-11). The gate effect is a selective process capable of discriminating between","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"26 1","pages":"22-29"},"PeriodicalIF":0.0,"publicationDate":"2013-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82269917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-30DOI: 10.2174/1874065001307010012
C. Uhlschmied, C. Krieg, G. Abel, M. Popp, C. Huck, G. Bonn
For sample preparation solid-phase extraction (SPE) became very popular during the 1980s and 1990s. Because method development and its optimization is very time consuming, in most cases C18 is used as standard carrier material without knowing if it possesses the highest efficiency. Therefore detailed studies with different stationary phases are necessary for optimal recovery rates. Due to the resulting high number of samples, automation is of crucial importance. In the study described, the extraction of five monoterpenoids (myrcene, citronellal, p-cymene, menthol and thymol) out of an ethanolic solution was optimized using automated SPE. An automated robotic system, the MEA Personal Purification System ® from PhyNexus™ Inc. (http://www.phynexus.com/), was adopted for high-throughput SPE. It allows the simultaneous automatic extraction of 12 samples in parallel employing different carrier materials. Additionally, critical parameters of automation (speed, volume uptake, skipping of drying step) were variegated to obtain optimal recovery rates. Furthermore, extraction efficiency was compared with manual handling to evaluate its performance. The application of 18 different SPE carrier materials, C18 Hydra, C18 ec, C8, C4, C2, C6H5, C6H11 ec, NO2, CN, NH2/C18, Diol, HR-P, EASY, PA, Florisil ® , Davisil ® , Strata-X ® and cellulose pointed out huge differences in extraction efficiency. Finally, the optimized automated procedure was applied for the enrichment of monoterpenoides and their analysis in selected real samples including cough drops, mouthwash and bath additives by gas-chromatography mass spectrometry (GC-MS).
固相萃取法(SPE)在20世纪80年代和90年代非常流行。由于方法开发和优化非常耗时，在大多数情况下，C18被用作标准载流子材料，而不知道它是否具有最高的效率。因此，有必要对不同固定相进行详细的研究，以获得最佳回收率。由于由此产生的大量样品，自动化是至关重要的。在本研究中，采用自动固相萃取的方法对从乙醇溶液中提取五种单萜类化合物(月桂烯、香茅醛、对伞花烯、薄荷醇和百里香酚)进行了优化。采用PhyNexus™Inc. (http://www.phynexus.com/)的自动化机器人系统MEA Personal Purification system®进行高通量SPE。它允许同时自动提取12个样品平行采用不同的载体材料。此外，自动化的关键参数(速度，体积吸收，跳过干燥步骤)是多样化的，以获得最佳的回收率。并将其提取效率与人工处理进行比较，评价其性能。采用C18 Hydra、C18 ec、C8、C4、C2、C6H5、C6H11 ec、NO2、CN、NH2/C18、Diol、HR-P、EASY、PA、Florisil®、Davisil®、Strata-X®和纤维素等18种不同的SPE载体材料，萃取效率差异较大。最后，将优化后的自动化流程应用于咳药水、漱口水和沐浴液添加剂等实际样品的单萜类化合物富集及气相色谱-质谱(GC-MS)分析。
{"title":"Evaluation of Commercial Solid-Phase Extraction (SPE) Carrier Materials for the Selective Automated Enrichment of Monoterpenoides and their Analysis in Cough Drops, Mouthwashes and Bath Additives by Gas- Chromatography Mass Spectrometry (GC-MS)","authors":"C. Uhlschmied, C. Krieg, G. Abel, M. Popp, C. Huck, G. Bonn","doi":"10.2174/1874065001307010012","DOIUrl":"https://doi.org/10.2174/1874065001307010012","url":null,"abstract":"For sample preparation solid-phase extraction (SPE) became very popular during the 1980s and 1990s. Because method development and its optimization is very time consuming, in most cases C18 is used as standard carrier material without knowing if it possesses the highest efficiency. Therefore detailed studies with different stationary phases are necessary for optimal recovery rates. Due to the resulting high number of samples, automation is of crucial importance. In the study described, the extraction of five monoterpenoids (myrcene, citronellal, p-cymene, menthol and thymol) out of an ethanolic solution was optimized using automated SPE. An automated robotic system, the MEA Personal Purification System ® from PhyNexus™ Inc. (http://www.phynexus.com/), was adopted for high-throughput SPE. It allows the simultaneous automatic extraction of 12 samples in parallel employing different carrier materials. Additionally, critical parameters of automation (speed, volume uptake, skipping of drying step) were variegated to obtain optimal recovery rates. Furthermore, extraction efficiency was compared with manual handling to evaluate its performance. The application of 18 different SPE carrier materials, C18 Hydra, C18 ec, C8, C4, C2, C6H5, C6H11 ec, NO2, CN, NH2/C18, Diol, HR-P, EASY, PA, Florisil ® , Davisil ® , Strata-X ® and cellulose pointed out huge differences in extraction efficiency. Finally, the optimized automated procedure was applied for the enrichment of monoterpenoides and their analysis in selected real samples including cough drops, mouthwash and bath additives by gas-chromatography mass spectrometry (GC-MS).","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"39 1","pages":"12-21"},"PeriodicalIF":0.0,"publicationDate":"2013-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90056215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-04-19DOI: 10.2174/1874065001307010006
Chin-Tong Tan
Ion chromatography (IC), utilizing an ion exclusion column coupled to a conductivity detector (CD) via a post column reactor, had been evaluated for quantifying the Total Carbon dioxide (TCO2) level in equine plasma. The concentrations obtained from the analysis of the ASE linearity set correlated with the results obtained when the measurement was done using a Beckman EL-ISE ® instrument (R 2 = 0.998). Equine blood was analyzed using both instruments and the averaged absolute difference for 30 samples was 0.4 mM. The IC method was considered suitable for use to determine the compliance of 36 mM available CO2 per liter of plasma concentration threshold stated in the Malayan Racing Association's (MRA) Regulations.
{"title":"Evaluation of Ion Exclusion Chromatography as a Method for Determining the Total Carbon Dioxide (TCO2) Concentration in Equine Plasma","authors":"Chin-Tong Tan","doi":"10.2174/1874065001307010006","DOIUrl":"https://doi.org/10.2174/1874065001307010006","url":null,"abstract":"Ion chromatography (IC), utilizing an ion exclusion column coupled to a conductivity detector (CD) via a post column reactor, had been evaluated for quantifying the Total Carbon dioxide (TCO2) level in equine plasma. The concentrations obtained from the analysis of the ASE linearity set correlated with the results obtained when the measurement was done using a Beckman EL-ISE ® instrument (R 2 = 0.998). Equine blood was analyzed using both instruments and the averaged absolute difference for 30 samples was 0.4 mM. The IC method was considered suitable for use to determine the compliance of 36 mM available CO2 per liter of plasma concentration threshold stated in the Malayan Racing Association's (MRA) Regulations.","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"11 1","pages":"6-11"},"PeriodicalIF":0.0,"publicationDate":"2013-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74707898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-08-24DOI: 10.2174/1874065001206010039
N. Agnihotri
Hydroxy-2-(4'-methoxyphenyl)-4-oxo-4H-l-benzopyran (HMPB) forms a yellow colored (1:3) complex with niobium (V), which is extracted into dichloromethane from 1.04-4.40 molL -1 HClO4 solution showing an absorption maximum at 398 - 412 nm (figure curve A: 1.0 μg Nb ml -1 versus blank; curve B: blank versus DCM) with Beer's law range of 0-1.3 μg Nb ml -1 , molar absorptivity of 3.764 10 4 L mol -1 cm -1 and the detection limit as 0.036 μg ml -1 . The results are highly reproducible with a standard deviation of ± 0.0037. The linear regression equation is Y=0.399X + 0.006 and the correlation coefficient, r = 1.0004 The method is free from the interference of a large number of analytically important elements. The proposed method handles satisfactorily the analysis of several samples of varying complexity. the niobium concentration range of 0-1.3 μg Nb ml -1 , with a molar absorptivity and Sandell's sensitivity of 3.764 10 4 L mol -1 cm -1 and 0.0025 μg Nb cm -2 , respectively at 405 nm. The linear regression equation of the method is Y=0.399X + 0.006 and the correlation coefficient, r = 1.0004. The method is highly reproducible with a standard deviation of ± 0.0037 and the detection limit 0.036 μg ml -1 . Out of a number of
羟基-2-(4′-甲氧基苯基)-4-氧- 4h -l-苯并吡喃(HMPB)与铌(V)形成黄色(1:3)配合物，从1.04-4.40 mol -1 HClO4溶液中提取到二氯甲烷中，在398 - 412 nm处吸收最大(图曲线a: 1.0 μ Nb ml -1相对空白;曲线B:空白与DCM)，比尔定律范围为0 ~ 1.3 μ Nb ml -1，摩尔吸光度为3.76410.4 L mol -1 cm -1，检出限为0.036 μ ml -1。结果重复性好，标准偏差为±0.0037。线性回归方程为Y=0.399X + 0.006，相关系数r = 1.0004，该方法不受大量重要分析元素的干扰。所提出的方法能令人满意地处理不同复杂程度的几种样品的分析。铌的浓度范围为0 ~ 1.3 μg Nb ml -1，在405 nm处的摩尔吸光度和桑德尔灵敏度分别为3.76410.4 L mol -1 cm -1和0.0025 μg Nb cm -2。方法的线性回归方程为Y=0.399X + 0.006，相关系数r = 1.0004。方法重复性好，标准偏差为±0.0037，检出限为0.036 μ ml -1。从…中
{"title":"Extractive Spectrophotometric Determination of Niobium (V) Using 3- Hydroxy-2-(4'-Methoxyphenyl)-4-Oxo-4H-l-Benzopyran as a Complexing Agent","authors":"N. Agnihotri","doi":"10.2174/1874065001206010039","DOIUrl":"https://doi.org/10.2174/1874065001206010039","url":null,"abstract":"Hydroxy-2-(4'-methoxyphenyl)-4-oxo-4H-l-benzopyran (HMPB) forms a yellow colored (1:3) complex with niobium (V), which is extracted into dichloromethane from 1.04-4.40 molL -1 HClO4 solution showing an absorption maximum at 398 - 412 nm (figure curve A: 1.0 μg Nb ml -1 versus blank; curve B: blank versus DCM) with Beer's law range of 0-1.3 μg Nb ml -1 , molar absorptivity of 3.764 10 4 L mol -1 cm -1 and the detection limit as 0.036 μg ml -1 . The results are highly reproducible with a standard deviation of ± 0.0037. The linear regression equation is Y=0.399X + 0.006 and the correlation coefficient, r = 1.0004 The method is free from the interference of a large number of analytically important elements. The proposed method handles satisfactorily the analysis of several samples of varying complexity. the niobium concentration range of 0-1.3 μg Nb ml -1 , with a molar absorptivity and Sandell's sensitivity of 3.764 10 4 L mol -1 cm -1 and 0.0025 μg Nb cm -2 , respectively at 405 nm. The linear regression equation of the method is Y=0.399X + 0.006 and the correlation coefficient, r = 1.0004. The method is highly reproducible with a standard deviation of ± 0.0037 and the detection limit 0.036 μg ml -1 . Out of a number of","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"8 1","pages":"39-44"},"PeriodicalIF":0.0,"publicationDate":"2012-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82034090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-08-08DOI: 10.2174/1874065001206010022
I. Ahmad, Ambreen Hafeez, N. Akhter, F. Vaid, Kiran Qadeer
The kinetics of photolysis of cyanocobalamin (CC) by visible radiation in the presence of riboflavin (RF) at pH 2.0-12.0 has been studied. A specific two-component spectrophotometric method has been used for the simultaneous assay of CC and its photoproduct, hydroxocobalamin (HC), at 525 and 550 nm, without any interference from RF. The apparent first-order rate constants for the photolysis of CC in the presence of 1-5 � 10 -5 M concentrations of RF at pH 2.0- 12.0 range from 0.46 (pH 7.0) to 4.22 � 10 -3 min -1 (pH 3.5). The second-order rate constants for the bimolecular interaction of these vitamins are in the range of 8.66 (pH 7.5) to 45.20 M -1 min -1 (pH 2.0). The rate-pH profile indicates a gradual decrease in rate in the acid pH range followed by the slowest rate and maximum stability around pH 7-8. Thus the cationic form of CC is more susceptible to photolysis compared to the neutral form. The increase in rate in the alkaline region is probably due to the hydrolysis of the amide groups. The kinetic results indicate that RF acts as a sensitizer in the photolysis of CC and in this way promotes the degradation of the molecule. Thus the presence of RF in CC solutions adversely affects the stability of vitamin B12.
研究了核黄素(RF)存在下，在pH 2.0 ~ 12.0范围内可见光光解氰钴胺素(CC)的动力学。采用一种特殊的双组分分光光度法，在525和550 nm处同时测定CC及其光产物羟钴胺素(HC)，不受RF干扰。在pH 2.0- 12.0条件下，1-5 μ 10 -5 μ M浓度的RF存在下，CC光解的一级表观速率常数范围为0.46 (pH 7.0)至4.22 μ 10 -3 min -1 (pH 3.5)。这些维生素的双分子相互作用的二级速率常数在8.66 (pH 7.5)至45.20 M -1 min -1 (pH 2.0)之间。速率-pH曲线表明，在酸性pH范围内，速率逐渐降低，其次在pH 7-8附近速率最慢，稳定性最大。因此，阳离子形式的CC比中性形式更容易光解。在碱性区速率的增加可能是由于酰胺基团的水解。动力学结果表明，RF在CC光解过程中起敏化剂的作用，从而促进了分子的降解。因此，CC溶液中RF的存在会对维生素B12的稳定性产生不利影响。
{"title":"Effect of Riboflavin on the Photolysis of Cyanocobolamin in AqueousSolution","authors":"I. Ahmad, Ambreen Hafeez, N. Akhter, F. Vaid, Kiran Qadeer","doi":"10.2174/1874065001206010022","DOIUrl":"https://doi.org/10.2174/1874065001206010022","url":null,"abstract":"The kinetics of photolysis of cyanocobalamin (CC) by visible radiation in the presence of riboflavin (RF) at pH 2.0-12.0 has been studied. A specific two-component spectrophotometric method has been used for the simultaneous assay of CC and its photoproduct, hydroxocobalamin (HC), at 525 and 550 nm, without any interference from RF. The apparent first-order rate constants for the photolysis of CC in the presence of 1-5 � 10 -5 M concentrations of RF at pH 2.0- 12.0 range from 0.46 (pH 7.0) to 4.22 � 10 -3 min -1 (pH 3.5). The second-order rate constants for the bimolecular interaction of these vitamins are in the range of 8.66 (pH 7.5) to 45.20 M -1 min -1 (pH 2.0). The rate-pH profile indicates a gradual decrease in rate in the acid pH range followed by the slowest rate and maximum stability around pH 7-8. Thus the cationic form of CC is more susceptible to photolysis compared to the neutral form. The increase in rate in the alkaline region is probably due to the hydrolysis of the amide groups. The kinetic results indicate that RF acts as a sensitizer in the photolysis of CC and in this way promotes the degradation of the molecule. Thus the presence of RF in CC solutions adversely affects the stability of vitamin B12.","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2012-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85820124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-08-08DOI: 10.2174/1874065001206010028
M. Sasaki
Simultaneous determinations exploiting the rates of reactions of different analytes with a common reagent, often referred to as differential kinetic analysis, is efficiently implemented in the flow analyser. To this end, specific strategies for pumping, commuting and/or detecting have been proposed. This review critically discusses the potentialities, limitations and application ranges of the different flow systems designed to accomplish differential reaction- rate methods, with emphasis to those involving spectrophotometric and luminometric detection.
{"title":"Differential Reaction-Rate Methods in Flow Analysis","authors":"M. Sasaki","doi":"10.2174/1874065001206010028","DOIUrl":"https://doi.org/10.2174/1874065001206010028","url":null,"abstract":"Simultaneous determinations exploiting the rates of reactions of different analytes with a common reagent, often referred to as differential kinetic analysis, is efficiently implemented in the flow analyser. To this end, specific strategies for pumping, commuting and/or detecting have been proposed. This review critically discusses the potentialities, limitations and application ranges of the different flow systems designed to accomplish differential reaction- rate methods, with emphasis to those involving spectrophotometric and luminometric detection.","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"8 1","pages":"28-38"},"PeriodicalIF":0.0,"publicationDate":"2012-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82830926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-16DOI: 10.2174/1874065001206010015
L. Dubey, I. Chianella, I. Dubey, E. Piletska, M. Whitcombe, S. Piletsky
Affinity polymeric adsorbents useful for the separation of compounds which are derivatives of phenols, heterocycles and other compounds containing two polar moieties were prepared by a covalent imprinting approach. Such separation, for example, would facilitate the analytical detection and quantification of each individual compound especially when present in complex sample matrix. The synthetic method, utilised for the preparation of the polymers, is based on co-polymerization of diacrylate esters of hydroxyphenols (catechol, resorcinol and hydroquinone) with an appropriate cross-linker followed by alkaline hydrolysis of the esters and release of the corresponding phenol. The resulting swellable materials contain cavities with adjustable size and orientation of two carboxylic groups suited for the binding of molecules with appropriate size and complementary orientation of polar groups. In contrast to conventional MIPs the synthesized polymers have selectivity not only for the phenolic templates, but also for a group of compounds with suitable orientations of polar functionalities, such as aromatic nitrogen, amino or hydroxyl groups. Polymers demonstrated different affinity to ortho-, meta- and para-isomers of hydroxyphenols, hydroxypyridines and diazine heterocycles.
{"title":"Selective Recognition of Bifunctional Molecules by Synthetic Polymers Prepared by Covalent Molecular Imprinting","authors":"L. Dubey, I. Chianella, I. Dubey, E. Piletska, M. Whitcombe, S. Piletsky","doi":"10.2174/1874065001206010015","DOIUrl":"https://doi.org/10.2174/1874065001206010015","url":null,"abstract":"Affinity polymeric adsorbents useful for the separation of compounds which are derivatives of phenols, heterocycles and other compounds containing two polar moieties were prepared by a covalent imprinting approach. Such separation, for example, would facilitate the analytical detection and quantification of each individual compound especially when present in complex sample matrix. The synthetic method, utilised for the preparation of the polymers, is based on co-polymerization of diacrylate esters of hydroxyphenols (catechol, resorcinol and hydroquinone) with an appropriate cross-linker followed by alkaline hydrolysis of the esters and release of the corresponding phenol. The resulting swellable materials contain cavities with adjustable size and orientation of two carboxylic groups suited for the binding of molecules with appropriate size and complementary orientation of polar groups. In contrast to conventional MIPs the synthesized polymers have selectivity not only for the phenolic templates, but also for a group of compounds with suitable orientations of polar functionalities, such as aromatic nitrogen, amino or hydroxyl groups. Polymers demonstrated different affinity to ortho-, meta- and para-isomers of hydroxyphenols, hydroxypyridines and diazine heterocycles.","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"9 1","pages":"15-21"},"PeriodicalIF":0.0,"publicationDate":"2012-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88898327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-03-26DOI: 10.2174/1874065001206010001
E. M. Kuskoski, J. Ríos, J. M. Bueno, R. Fett, A. Troncoso, A. Asuero
The GC-MS analysis of phenolic compounds present in guarana (Paullinia cupana), an important product of the Amazonian forest consumed in supplements or in soft drinks has been the subject of study. The therapeutic properties and possible protective effects reported for guarana and derivative products could be associated with the antioxidant activity of their phenolics content. The purpose of this study is i) to provide molecular structural information about the composition of guarana in phenolics; ii) to ascertain the effect of solvent type on the extraction procedure; and iii) to determine the antioxidant activity of powders, pericarp, pulp seeds, capsules and bar from Paullinia cupana, as oxygen radical absorbance capacity with fluorescein (ORACFL). Three more phenolic compounds, Quercetin, (+)-Catechin and (- )-Epicatechin have been identified in this report as trimethylsilyl (TMS) derivatives. The amount of total phenolics found in plant materials containing guarana varied from 25.10 to 124.99 mg of gallic acid/g dry sample whereas that the antioxidant activity ranged from 441.5 to 1468.3 μmol TEAC/g dry sample. A high correlation was found between the estimated phenolic contents and the TEAC values (r = 0.937, P< 0.01) for all the types of guarana samples tested.
{"title":"Capillary Gas Chromatography-Mass Spectrometry (CGC-MS) Analysis and Antioxidant Activities of Phenolic and Components of Guarana and Derivatives","authors":"E. M. Kuskoski, J. Ríos, J. M. Bueno, R. Fett, A. Troncoso, A. Asuero","doi":"10.2174/1874065001206010001","DOIUrl":"https://doi.org/10.2174/1874065001206010001","url":null,"abstract":"The GC-MS analysis of phenolic compounds present in guarana (Paullinia cupana), an important product of the Amazonian forest consumed in supplements or in soft drinks has been the subject of study. The therapeutic properties and possible protective effects reported for guarana and derivative products could be associated with the antioxidant activity of their phenolics content. The purpose of this study is i) to provide molecular structural information about the composition of guarana in phenolics; ii) to ascertain the effect of solvent type on the extraction procedure; and iii) to determine the antioxidant activity of powders, pericarp, pulp seeds, capsules and bar from Paullinia cupana, as oxygen radical absorbance capacity with fluorescein (ORACFL). Three more phenolic compounds, Quercetin, (+)-Catechin and (- )-Epicatechin have been identified in this report as trimethylsilyl (TMS) derivatives. The amount of total phenolics found in plant materials containing guarana varied from 25.10 to 124.99 mg of gallic acid/g dry sample whereas that the antioxidant activity ranged from 441.5 to 1468.3 μmol TEAC/g dry sample. A high correlation was found between the estimated phenolic contents and the TEAC values (r = 0.937, P< 0.01) for all the types of guarana samples tested.","PeriodicalId":90363,"journal":{"name":"The open analytical chemistry journal","volume":"103 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2012-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79525857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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