Autoadaptative sequential injection system for nitrite determination in wastewaters

A novel autoadaptative sequential injection system for the analysis of nitrite is described. The automatic determination uses a direct spectrophotometric method, based on the Griess-Ilosvay reaction. In this method the absorbance of the purple azo dye formed is measured at 555 nm. In the sequential injection operation, the sample and the reagent are aspirated and mixed by reverse flow. The sequencing and overlapping of stacked (reagent) zones as well as selection of volumes have been studied in detail. The proposed analytical system is intelligent, simple and robust, allowing for nitrite determination in a double concentration range, by a simple and automatic programmable operation change. These two ranges are 0.0-3.0 and 0.0-20.0 ppm with detection limits being 0.048 and 0.4 ppm, respectively. Next surroundings have been developed allowing autocalibration and independent monitoring of nitrite concentration. The experimental set-up has been evaluated applying it to real samples analysis of very diverse concentration samples coming from a WWTP. The throughput of the method was 12 samples per hour.     

Spectrophotometric determination of nickel with biacetyl bis(4-phenyl-3-thiosemicarbazone)

A simple method is described for the rapid spectrophotometric determination of nickel with biacetyl bis(4-phenyl-3-thiosemicarbazone). The yellow color is measured at 460 nm (? = 22,800 liters mol^?1 cm^?1) against a reagent blank at pH 2.5 in a solution containing 60% ($\text{v}\text{v}$) dimethylformamide. Beer's law is obeyed over the range 0.2–2 ppm of nickel.     

FTIR, 1H NMR,ESR, TGA and DTA Analysis of Trithiocarbonates of Captopril and 6‐Mercaptopurine as Their Palladium(II) Chloride Complexes

A simple and sensitive spectrophotometric method has been developed for the determination of the antihypertensive drug captopril and anticancer drug 6‐mercaptopurine, in their trithiocarbonate (TTC) form by using Pd(II) chloride as a coloring reagent. Captopril TTC forms a stable dark yellow colored complex with λ_max 383 nm, molar absorption coefficient 1.35 × 10⁵ l/mole/cm and a Beer's law range from 0.084‐1.26 ppm. 6‐Mercaptopurine TTC forms a stable deep yellow colored complex with λ_max 345 nm, molar absorption coefficient 6.9 × 10⁵ l/mole/cm and a Beer's law range from 0.0319 ppm to 3.519 ppm. The M: L ratio of palladium: TTC complexes were confirmed by Job's method of continuous variance and mole ratio method and was found to be 1:1 for both captopril TTC as well as 6‐mercaptopurine TTC. In addition, on the basis of, FTIR, ¹H NMR, ESR and thermal analysis data a plausible structure of mononuclear Pd(II) complex of Captopril TTC and 6‐mercaptopurine TTC has been reported.     

A simple spectrophotometric determination of endosulfan in river water and soil

Summary A simple spectrophotometric determination of endosulfan (Thiodan), a sulphur containing pesticide is described. The method is based on the liberation of sulphur dioxide from endosulfan which is subsequently absorbed into an absorbing reagent, malonyldihydrazide and estimated by using p-aminoazobenzene and formaldehyde to give a pink coloured dye which has an absorbance maxima at 505 nm. The Beer's law is obeyed in the range of 1–6 ppm for a standard solution of endosulfan. The method can be easily applied in river water and soil samples to determine endosulfan levels as low as 0.05 ppm and 0.25 ppm in river water and soil, respectively. The method is free from the interference of most of the commonly used pesticides and foreign ions.     

Spectrophotometric Determination of Sulphathiazole

Abstract

A new, rapid, simple, selective and sensitive method for the spectrophotometric determination of sulphathiazole is described. The drug forms a yellow coloured complex with Pd(II) in alkaline medium (1 M NaOH). The drug complex exhibits maximum absorbance at 410 nm, with a molar absorptivity of 1.9 × 10³ 1 mol^?1 cm^?1. Effects of molarity of NaOH, reagent concentration on the proper complex formation are discussed. The system obeys Beer's law in the concentration range of 10-160 ppm of sulphathiazole.     

A simple microfluidic chlorine gas sensor based on gas-liquid chemiluminescence of luminol-chlorine system

In this work, a microfluidic chlorine gas sensor based on gas-liquid interface absorption and chemiluminescence detection was described. The liquid chemiluminescence reagent-alkaline luminol solution can be stably sandwiched between two convex halves of a microchannel by surface tension. When chlorine gas was introduced into the micro device, it was dissolved into the interfacial luminol solution and transferred to ClO(-), and simultaneously luminol was excited and chemiluminescence emitted. The emitted chemiluminescence light was perpendicularly detected by a photomultiplier tube on a certain detection region. The remarkable advantage of the detection system is that both adsorption and detection were carried out at the gas-liquid interface, which avoids the appearance of bubbles. The whole analytical cycle including filling CL reagent, sample injection, CL detection and emptying the device was as short as 30 s. The linear concentration range of chlorine gas detection with direct introduction of sample method is from 0.5 to 478 ppm. The detection limit of this method is 0.2 ppm for standard chlorine gas and the relative standard deviation of five determinations of 3.19 ppm spiked chlorine sample was 5.2%.     

Analytical investigations on cephalosporins--IV: application of Ellman's reagent

The application of 5,5'-dithiobis(2-nitrobenzoic acid) (Ellman's reagent) for the determination of microgram quantities of various selected cephalosporins in aqueous solution is described. Cephalosporin derivatives (cephalothin sodium, cephacetrile sodium, cefamandole lithium and nafate, cefoperazone sodium and ceftizoxime sodium) have to be treated with 0.5N sodium hydroxide before determination with Ellman's reagent, which reacts with free thiol groups. An aliquot of the solution is reacted with Ellman's reagent in pH 7.2 phosphate buffer and the absorbance of the resulting yellow solution is measured at 410 nm. The method, which is simple and precise, has been applied to determination of those cephalosporins in formulations, the results being compared with those obtained by the Ni-hydroxylamine method.     

A Sensitive Colorimetric Reagent for the Determination of Cyanide and Hydrogen Cyanide in Various Environmental Samples

A sensitive reagent system is proposed for the determination of cyanide and hydrogen cyanide in various environmental samples. The method is based on the conversion of cyanide into cyanogen bromide followed by its reaction with pyridine to form glutaconic aldehyde. The glutaconic aldehyde so formed is coupled with p‐aminoacetophenone forming yellow‐orange polymethine dye measured at 445 nm. The colour system obeys Beer's law in the range of 0.01–0.16 ppm of cyanide inaqeous phase and 0.002–0.03 ppm in extracting system. The molar absorptivity and Sandell's sensitivity were found to be 6.51 × 10⁵ l mol^?1 cm^?1 and 0.0001 μg cm^?2, respectively. The method has been successfully applied for the determination of cyanide in air, industrial effluent, biological samples, and in the pesticide acrylonitrile.     

Benzeneacetaldehyde-4-hydroxy-alpha-oxo-aldoxime as a new analytical reagent for the spectrophotometric determination of cobalt

Benzeneacetaldehyde-4-hydroxy-α-oxo-aldoxime is proposed as a new sensitive and selective reagent for the spectrophotometric determination of cobalt. The reagent reacts with cobalt in the pH range 8.6–9.4 to form a yellow colored 1:3 chelate which is very well extracted in chloroform. Beer's law is obeyed in the concentration range 0.05–1.3 μg ml⁻¹ cobalt. The molar absorptivity of the extracted species is 2.746×10⁴ l mol⁻¹ cm⁻¹ at 390 nm. The proposed method is highly sensitive, selective, simple, rapid, accurate and has been satisfactorily applied for the determination of cobalt in synthetic mixtures, pharmaceutical samples, biological samples and alloys.     

Spectrophotometric Determination of Iron In Wines,Vegetables, Pharmaceutical Compounds and Minerals With Mandelohydroxamic Acid (Mha)

Abstract

A new reagent, mandelohydroxamic acid (MHA), which has an easy synthesis and an high water solubility (64.48 gL^?1) is proposed for a simple, rapid, selective and sensitive method for the spectrophotometric determination of iron based upon the formation of the MHA-Fe(III) complex and its extraction into n-butanol under optimum operating conditions. A yellow color is formed when the complex is extracted from acidic aqueous medium (Vw/Vo[dbnd]5) in the organic solvent (apparent molar absortivity 1.15 10⁴ L mol^?1 cm^?1 at a wavenlength of 430 nm). the relative error is 0.5% (2 ppm of iron) and the detection limit is 0.05 g mL^?1 of Fe(III). the method has been applied to the determination of iron in wines, vegetables, pharmaceutical compounds and minerals.     

Development and application of organic reagents for analysis-VII Extraction and fluorimetric determination of perchlorate ions with 2,6-di-p-tolyl-4-phenylpyrylium chloride

An extraction-fluorimetric method for the determination of micro quantities of perehlorate ions, based on their extraction into chlorobenzene with 2,6-di-p)-tolyl-4-phenylpyrylium chloride (DTPP(+)-Cl(-)) has been developed. DTPF(+)-Cl(-), a newly synthesized reagent, reacts with perchlorate ions to form 1:1 ion-pairs, which can be extracted into chlorobenzene. The ion-pair (DTPP(+)-ClO(4)(-)) has very strong yellowish-green fluorescence in chlorobenzene, with an emission maximum at 376 nm. The relationship between perchlorate ion concentration and relative fluorescence intensity is linear over the range 0.01-1.0 ppm. Several inorganic perchlorates have been determined satisfactorily by the method.     

高效液相色谱法测定糕点中的柠檬黄、日落黄

建立高效液相色谱法测定糕点中的柠檬黄、日落黄的方法。样品经水浸泡提取,于涡旋混匀器中快速混匀,浸泡放置过夜,取离心后的上清液,以甲醇和乙酸铵溶液梯度淋洗,用紫外检测器检测,柠檬黄、日落黄分别采用430 nm和482 nm检测波长。线性相关系数为0.999,柠檬黄、日落黄的检出限分别为0.4,0.3 mg/kg。样品加标回收率为72.5%~82.0%,柠檬黄、日落黄测定结果的相对标准偏差分别为4.8%和3.7%(n=5)。方法简便快捷,节省试剂,减少了杂质干扰,提高了灵敏度。     

Extraction and Spectrophotometric Determination of Arsenic in the Environment

Abstract

A simple, sensitive and selective method for the determination of microamounts of arsenic (III) in the environment is described. Arsenic forms a yellow coloured complex with N-phenylbenzo-hydroxamic acid (PBHA) at pH 4.5-5.2 which can be extracted from chloroform. The effective molar absorptivity of As-PBHA extract is 1.1 × 1mol^?1cm^?1 at 410 nm. Many common ions associated with arsenic do not interfere. The effect of pH, reagent concentration and solvent is described. The arsenic in trace quantities is estimated in the industrial effluents, soil and glass samples.     

Microscreening toxicity system based on living magnetic yeast and gradient chips

There is an increasing demand for easy and cost-effective methods to screen the toxicological impact of the growing number of chemical mixtures being generated by industry. Such a screening method has been developed using viable, genetically modified green fluorescent protein (GFP) reporter yeast that was magnetically functionalised and held within a microfluidic device. The GFP reporter yeast was used to detect genotoxicity by monitoring the exposure of the cells to a well-known genotoxic chemical (methyl methane sulfonate, MMS). The cells were magnetised using biocompatible positively charged PAH-stabilised magnetic nanoparticles with diameters around 15 nm. Gradient mixing was utilised to simultaneously expose yeast to a range of concentrations of toxins, and the effective fluorescence emitted from the produced GFP was measured. The magnetically enhanced retention of the yeast cells, with their facile subsequent removal and reloading, allowed for very convenient and rapid toxicity screening of a wide range of chemicals. This is the first report showing magnetic yeast within microfluidic devices in a simple bioassay, with potential applications to other types of fluorescent reporter yeast in toxicological and biomedical research. The microfluidic chip offers a simple and low-cost screening test that can be automated to allow multiple uses (adapted to different cell types) of the device on a wide range of chemicals and concentrations.     

Rapid Extraction Spectrophotometric Determination of Platinum Using Anisaldehyde-4-Phenyl-3-Thiosemicarbazone as a Chromogenic Reagent

Abstract

The synthesis, spectral characteristics and analytical applications of anisaldehyde-4-phenyl-3-thiosemicarbazone (APT) are described. A simple, rapid, selective and sensitive spectrophotometric method for the determination of platinum was developed based on the colour reaction between platinum (IV) and anisaldehyde-4-phenyl-3-thio-semicarbazone (APT) in the pH range 1.7 - 3.0. The yellow coloured species has an absorption maximum at 360 nm. The complexation is complete within 1 min. A five-fold excess of the reagent is required for complete complex formation. Beer's law is obeyed over the concentration range 0.1 -20 ppm of Pt(IV). The mtilar absorptivity and Sandell's sensitivity are 1.58 × 10⁴ l. mol^?1 cm^?1 and 0.0123 ug of Pt(IV) cm^?2, respectively. The effects of pH, time concentration of reagent, order of addition of reagents and the interference from various ions were investigated. The method has been employed for the determination of platinum in synthetic mixtures whose composition correspond to some alloys.     

Studies on pollutants: A new reagent for the detection of fluoride

A new solid analytical reagent is reported for the detection and semiquantitative determination of traces of fluoride. A blue (λ_max 590 nm) trypan blue dye is liberated from an insoluble zirconium-trypan blue complex by the action of fluoride in dilute acetic acid medium. The detection limit is 0.8 ppm and the range of semiquantitative determination is 0.8 to 8 ppm. The method is simple and can be conveniently used for field detection of fluoride in polluted waters.     

Synthesis of New Reagent Benzyloxybenzaldehydethiosemicarbazone (BBTSC): Selective,Sensitive and Extractive Spectrophotometric Determination of Pd(II) in Water Samples and Synthetic Mixtures

A new reagent, benzyloxybenzaldehydethiosemicarbazone (BBTSC) was synthesized and a new method was developed for the simple, highly selective and extractive spectrophotometric determination of palladium(II) with BBTSC at wave length 365 nm. The metal ion formed a yellow colored complex with BBTSC in acetate buffer of pH 5.0, which was easily extractable into cyclohexanol with 1:1 (Metal: Ligand) composition. The method obeys Beer's law in the range of 5–60 ppm. The molar absorptivity and Sandell's sensitivity were found to be 0.4 × 10⁴ Lt. mol^?1 cm^?1 and 0.02661 μg cm^?2, respectively. The correlation co‐efficient of the Pd(II)‐BBTSC complex was 0.9657, which indicated an excellent linearity between the two variables. The repeatability of the method was checked by finding the relative standard deviation (RSD) (n = 10), which was 0.321% and its detection limit 0.016875 μg.mL^?1. The instability constant of the method was calculated by Asmus' method as 3.5714 × 10^?4. The interfering effect of various cations and anions were also studied. The proposed method was successfully applied for the determination of palladium(II) in synthetic and water samples. The results were compared with those obtained using an atomic absorption spectrophotometer, testing the validity of the method.     

Solvent extraction and spectrophotometric determination of uranium(VI) with pyridine-2-carboxaldehyde 2-hydroxybenzoylhydrazone

Pyridine-2-carboxaldehyde 2-hydroxybenzoylhydrazone (PAHB) is proposed as an extractant for the separation and spectrophotometric determination of uranium(VI). The optimum extraction conditions have been evaluated by studying various parameters such as pH, diluents, equilibration time and reagent concentration. PAHB forms yellow colored complex with uranium(VI) in the pH range of 3.5-4.6 which can be extracted by isobutyl methyl ketone. The extracted complex exhibits an absorption maximum at 375 nm. Beer's law was obeyed in the concentration range 1.0-5.6 ppm of uranium(VI). The nature of the extracted species (1:2) was determined by log D-log c plot. The proposed method permits selective separation of uranium(VI) from its binary mixtures. The method is also applied for the estimation of uranium in multicomponent mixtures and monazite sand.     

生化芯片上的光纤消逝波吸收光度检测

生化芯片上探测器的总体性能将影响整个芯片分析系统的检出限、检测速度和适用范围等指标,是芯片分析系统的一个关键部分.针对生化芯片检测区的检测体积小、样品剂量少以及与生化芯片集成等特殊要求,设计了易于集成在芯片内的,用分光光度法对混合后液体的消逝波吸收光谱探测的方法.     

On-chip sample pretreatment using a porous polymer monolithic column for solid-phase microextraction and chemiluminescence determination of catechins in green tea

A porous polymer monolithic column for solid-phase microextraction and chemiluminescence detection was integrated into a simple microfluidic chip for the extraction and determination of catechins in green tea. The porous polymer was prepared by poly(glycidyl methacrylate-co-ethylene dimethacrylate) and modified with ethylenediamine. Catechins can be concentrated in the porous polymer monolithic column and react with potassium permanganate to give chemiluminescence. The microfluidic chip is reusable with high sensitivity and very low reagent consumption. The on-line preconcentration and detection can be realized without an elution step. The enrichment factor was calculated to be about 20 for catechins. The relative chemiluminescence intensity increased linearly with concentration of catechin from 5.0 × 10(-9) to 1.0 × 10(-6) M and the limit of detection was 1.0 × 10(-9) M. The proposed method was applied to determine catechin in green tea. The recoveries are from 90% to 110% which benefits the actual application for green tea samples.