A New Chromogenic Spray Reagent for Detection and Identification of Monocrotophos

JPC – Journal of Planar Chromatography – Modern TLC - Sensitive and selective detection of monocrotophos after TLC is possible by use of vanillin as reagent. The product from alkaline...     

A New Chromogenic Spray Reagent for the Detection and Identification of Monocrotophos

JPC – Journal of Planar Chromatography – Modern TLC -     

A Novel Method for the Determination of Streptomycin Using Sodium Nitroprusside as a Chromogenic Reagent by Spectrophotometry

Abstract

A rapid and simple spectrophotometric method for the determination of streptomycin has been developed and validated. The method was based on the reaction of streptomycin with sodium nitroprusside in the alkaline medium forming a red product measured at the maximum absorption of 495 nm. The stoichiometric ratio of the product is 1:1. Beer's law is obeyed in a range of 1.87 µg mL^?1 ～ 279.8 µg mL^?1 of streptomycin and ?₄₉₅ is 6.0 × 10³ L·mol^?1 cm^?1.Under the optimum condition, the equation of linear regression is A = 0.00742 + 0.05683 C (× 10⁵ mol·L^?1), with a linear correlation coefficient of 0.9990. The detection limit (3σ/k) is 0.96 µg mL^?1, the relative standard deviation (RSD) is 2.40%, and the average recovery rate is 98.3%–102.7%. Every parameter has been optimized, and the reaction mechanism has been studied. The proposed method has been successfully applied to the determination of streptomycin for injections and tablets of pharmaceutical preparation. Analytical results obtained by this new method were very gratifying.     

Thin Layer Chromatographic Technique for Detection and Identification of Endosulfan Insecticide with m-Dinitrobenzene Reagent

JPC – Journal of Planar Chromatography – Modern TLC - Endosulfan is commonly encountered in poisoning cases in India. In TLC the compound can be detected by spraying the plate with...     

硝普钠与苯肼的反应

有氧存在下 ,硝普钠 (Na2 [Fe(CN) 5NO] )与苯肼类化合物在N ,N 二甲基甲酰胺中作用 ,发生脱肼反应 ,生成叠氮苯、苯衍生物、微量的苯胺及偶氮化合物 .对可能的反应机理进行了讨论     

硝普钠分光光度法测定头孢他啶

建立了硝普钠分光光度法测定头孢他啶的方法。实验结果表明,在碱性条件下,头孢他啶与硝普钠以1∶2的化学计量比反应形成一种红褐色产物,其最大吸收波长为528 nm。 头孢他啶在2.50~810 mg/L浓度范围内与吸光度呈良好线性关系,线性回归方程为A=0.02704+0.00218ρ(mg/L),线性相关系数r＝0.9987,表观摩尔吸收系数ε528=1.2×103 L/(mol·cm),检测限(3σ/k)为1.38 mg/L。 本方法操作简便、快速,成功用于药品中头孢他啶含量的测定。     

The Application of Ammonium Hydroxide and Sodium Hydroxide for Reagent Softening of Water

The calcium carbonate crystallization from aqueous solutions in the presence of alkali additives such as sodium hydroxide and ammonium hydroxide has been researched. It is found CaCO₃ crystallizes predominantly in the modification of aragonite in the presence of ammonium hydroxide. The calcium carbonate formation rate in an alkaline medium and the gaseous reaction products due to sorption of gas bubbles on crystal surfaces, affect the aragonite structure formation. It is shown use of ammonium hydroxide for water treatment can solve two urgent tasks such as water softening and exclusion sediment of deposits on the equipment surfaces by a calcium carbonate crystallization in the form of aragonite.     

Rapid and Convenient Method for the Determination of Sodium Nitroprusside in Aqueous Solution

Abstract

We propose a rapid and convenient method for the determination of sodium nitroprusside in aqueous solution. In alkaline medium and in the presence of dimethylsulfoxide, the concentration of the nitrite ions coming from the nitroprusside corresponds with the initial quantity of this compound.     

Utilization of Sodium Nitroprusside as an Intestinal Permeation Enhancer for Lipophilic Drug Absorption Improvement in the Rat Proximal Intestine

As advanced synthetic technology has enabled drug candidate development with complex structure, resulting in low solubility and membrane permeability, the strategies to improve poorly absorbed drug bioavailability have attracted the attention of pharmaceutical companies. It has been demonstrated that nitric oxide (NO), a vital signaling molecule that plays an important role in various physiological systems, affects intestinal drug absorption. However, NO and its oxidants are directly toxic to the gastrointestinal tract, thereby limiting their potential clinical application as absorption enhancers. In this study, we show that sodium nitroprusside (SNP), an FDA-approved vasodilator, enhances the intestinal absorption of lipophilic drugs in the proximal parts of the small intestine in rats. The SNP pretreatment of the rat gastrointestinal sacs significantly increased griseofulvin and flurbiprofen permeation in the duodenum and jejunum but not in the ileum and colon. These SNP-related enhancement effects were attenuated by the co-pretreatment with dithiothreitol or c-PTIO, an NO scavenger. The permeation-enhancing effects were not observed in the case of antipyrine, theophylline, and propranolol in the duodenum and jejunum. Furthermore, the SNP treatment significantly increased acidic glycoprotein release from the mucosal layers specifically in the duodenum and jejunum but not in the ileum and colon. These results suggest that SNP increases lipophilic drug membrane permeability specifically in the proximal region of the small intestine through disruption of the mucosal layer.     

Application of an Organophosphorus Reagent Depbt for Synthesis of Cycloheptapeptide

A cycloheptapeptide cyclo(Gly-Tyr-Gly-Gly-Pro-Phe-Pro), which was isolated and identified from one kind of Chinese medicinal herbs, was chosen as a model cyclopeptide, to evaluate an organophosphorus reagent, 3-(diethyloxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one(DEPBT) for synthesis of cyclopeptide and compared with two other organophosphorus reagents, DPPA and BOP.     

可检测有机磷农药残留的丝网印刷酶电极

制备了用于有机磷农药检测的电化学生物酶电极, 并从工作电极上修饰物的选择、测定电压的确定、生物酶电极预活化时间的选定、测定时间的选定、温度的影响、pH值的影响、底物浓度的影响、固定方法的选择、固定酶时温度和时间的影响等多方面对丝网印刷的生物酶电极进行了较为全面的研究, 应用经过优化的生物酶电极对有机磷农药乙基对氧磷进行了检测. 结果表明: 抑制率与乙基对氧磷浓度的常用对数在1.00×10^－7～1.00×10^－5 g•mL^－1范围内成线性关系, 线性回归方程为A/%＝267.2＋37.20lg[c/(g•mL^－1)], 相关系数r＝0.9882. 当信噪比为3时, 检出限为2.10 ng•mL^－1, 低于国家标准所要求的最低残留量.     

Electrochemical Detection in Liquid Chromatography: Application to Organometallic Speciation

Abstract

The development of a new technique for the measurement of organometallic species is presented. It combines the resolution of high performance liquid chromatography with sensitive electrochemical detection used in a reductive mode. Past difficulties with this detection system have been overcome including the choice of a suitable working electrode and purification of the solvent.

The redox behavior of the organometals in the chromatographic solvent was studied by cyclic voltammetry in order to optimize the detector cell potential.

A separation of organomercurials and a multielement organometal mixture demonstrate the applicability of the system. Linear calibration curves can be obtained over a wide concentration range the detection limit for trimethyllead cation is about 0.1 ng.     

硝普钠显色测定药物样品中甲巯咪唑

在溶液中NaOH浓度为6.7×10-3mol/L及0℃(冰水浴)条件下,反应时间为30 min,硝普钠与甲巯咪唑生成化学计量比为1碱性条件下硝普钠与甲巯咪唑反应生成化学计量比为1∶1的绿色产物,其最大吸收波长为610 nm。甲巯咪唑在4.8~48 mg/L浓度范围内与吸光度呈良好线性关系,线性回归方程为A=-0.0617 0.01329C(mg/L),相关系数r=0.9991;检出限为0.47 mg/L;相对标准偏差RSD=0.2%。本法成功用于测定片剂药品中甲巯咪唑的含量,平均回收率大于97.2%。     

A Novel Visible Spectrophotometric Method for the Determination of Methanol Using Sodium Nitroprusside as Spectroscopic Probe

A novel, rapid and reliable method has been established for the determination of methanol using sodium nitroprusside as a spectroscopic probe. This method indicates that the sodium nitroprusside can react with the methanol to form a colored product in the basic solution. The absorbance of the product is measured at the maximal absorption wavelength of 481 nm, and the amount of methanol can be calculated based on this absorbance. A good linear relationship of the concentration of methanol versus absorbance is observed with a linear range of 0.02‐6.0 mg mL^?1. The linear regression equation is A = 0.02484 + 0.29457C (mg mL^?1), with a correlation coefficient of 0.9991. The detection limit (3σ/k) is 0.012 mg mL^?1, while its R.S.D. is 1.5% and the recovery rate is 97.5‐102.5%. The parameters with regard to determination are optimized, and the reaction mechanism is discussed. This method has been successfully applied to determine methanol in variety of samples. Analytical results obtained by this new method were very gratifying.     

在丙酮增敏作用下硝普钠分光光度法测定盐酸吗啉胍

摘要：建立了可见分光光度法测定盐酸吗啉胍的新方法。研究表明,当NaOH浓度为0.13mol/L,在丙酮存在下硝普钠与盐酸吗啉胍反应生成紫色N-亚硝基类化合物,其最大吸收波长为508nm,表观摩尔吸光系数2.5×10³ L/（mol•cm）。盐酸吗啉胍浓度在0.38×10^-6~3.0×10^-4 g/mL范围内与吸光度呈现良好线性关系,线性回归方程A = 0.02292 + 0.01213c (10^-6 g/mL),线性相关系数r=0.9998,检测限(3σ/k)为0.25×10^-6 g/mL,RSD = 0.21%。本方法可用于药物样品和血清中盐酸吗啉胍含量的测定。     

Sodium Percarbonate: A Convenient Reagent for Oxidative Cleavage of A-Diketones

Sodium percarbonate has been found to be a mild and effective reagent for the oxidative cleavage of a-diketones to carboxylic acids     

Catalytic Chemosensing Assay for Selective Detection of Methyl Parathion Organophosphate Pesticide

Herein, a catalytic chemosensing assay (CCA), based on a bimetallic complex, [Ru^II(bpy)₂(CN)₂]₂(Cu^II)₂ (bpy=2,2′-bipyridine), is described. This complex integrates a task-specific catalyst (Cu^I-catalyst) and a signaling unit ([Ru^II(bpy)₂(CN)₂]) to specifically hydrolyze methyl parathion, a highly toxic organophosphate (OP) pesticide. The bimetallic complex catalyzed the hydrolysis of the phosphate ester to generate o,o-dimethyl thiophosphate (DTP) anion and 4-nitrophenolate. Intrinsically, 4-nitrophenolate absorbed UV/Vis light at λ_max=400 nm, creating the first level of the chemosensing signal. DTP interacted with the original complex to displace the chromophore, [Ru^II(bpy)₂(CN)₂], which was monitored by spectrofluorometry; this was classified as the second level of chemosensing signal. By integrating both spectroscopic and spectrofluorometric signals with a simple AND logic gate, only methyl parathion was able to provide a positive response. Other aromatic and aliphatic OP pesticides (diazinon, fenthion, meviphos, terbufos, and phosalone) and 4-nitrophenyl acetate provided negative responses. Furthermore, owing to the metal-catalyzed hydrolysis of methyl parathion, the CCA system led to the detoxification of the pesticide. The CCA system also demonstrated its catalytic chemosensing properties in the detection of methyl parathion in real samples, including tap water, river water, and underground water.     

Application of Carbon Nanotubes in the Extraction and Electrochemical Detection of Organophosphate Pesticides: A Review

Recent trends and challenges in developing carbon nanotubes (CNT) based sensors and biosensors for the detection of organophosphate (OP) pesticides and other organic pollutants in water are reviewed. CNT have superior electrical, mechanical, chemical, and structural properties over conventional materials such as graphite. At the same time CNT based sensors and biosensors are more efficient compared to the existing traditional techniques such as high-performance liquid chromatography or gas chromatography, because they can provide rapid, sensitive, simple, and low-cost on-field detection. The measurement protocols can be based on enzymatic and non-enzymatic detection. The enzyme acetylcholinesterase (AChE) is used with CNT for fabricating ultrasensitive biosensors for OP detection involving different immobilization schemes such as adsorption, crosslinking, and layer-by-layer self-assembly. This protocol relies on measuring the degree of enzyme inhibition as means of OP quantification. The other enzyme used along with CNT for OP detection is organophosphate hydrolase (OPH) which hydrolyzes the OP into detectable species that can be measured by amperometric or potentiometric methods. Different forms of CNT electrode materials can be used for fabricating such electrodes such as pure CNT and composite CNT. Due to their large surface area and hydrophobicity, CNT have also been used for the extraction and non-enzymatic electrochemical detection of OP with very high efficiency. The application of CNT and their novel properties for the adsorption and electrochemical detection of OP compounds is discussed in detail.     

Assay of Phenformin Hydrochloride in Pharmaceutics by Coupling with Sodium Nitroprusside

A novel and simple spectrophotometric method for the determination of phenformin hydrochloride using sodium nitroprusside as chromogenic reagent is developed in this paper. The experiment indicates that the sodium nitroprusside can react with the phenformin hydrochloride in a basic solution to form a product with colored N‐nitrosamines. The stoichiometric ratio of phenformin hydrochloride and sodium nitroprusside is 1:3 in the product. The maximal absorption wavelength (λ_max) of the product is 520 nm, ?₅₂₀ = 2.2 × 10³ Lmol^?1cm^?1. A Good linear relationship is obtained between the absorbance (A) and the concentration (C) of phenformin hydrochloride in a wide range of 0.20‐400 μg mL^?1. The equation of the linear regression is A = 0.03461 + 0.00907C (μg mL^?1) with a linear correlation coefficient of 0.9991. The detection limit is 0.13 μg mL^?1, and the relative standard deviation (R.S.D.) is 0.19%. The method is successfully applied to the determination of phenformin hydrochloride in tablet forms, and satisfactory recoveries are obtained.