Detection of amines by using the depolymerization of poly(chloroaldehydes)

A detector tube is described in which amine vapors cause decomposition of a chloral-dichloroacetaldehyde copolymer. Detection signal is based on the dissolution of the dye pinacyanole by the liberated chloroacetaldehyde monomers. Of the 77 amines tested, ammonia, allylamine, n-butylamine, isobutylamine, sec-butylamine, cyclohexylamine, diethylamine, dibutylamine, dipropylamine, and piperidine gave strongest tests. The limit of detection of diethylamine is approximately 2 μg. The sensitivity is increased about one order of magnitude if solution techniques are employed. Interferences appear to be few since 71 compounds representing 21 classes of compounds did not give a test.     

Use of Anisotropic Materials as Chemical Detectors

Abstract

The visual detection between crossed polarizers, of organic vapors on various liquid crystal films is reported. Non-selective detection is achieved in the ppm range. However, opportunities exist for bettering selectivity and sensitivity as illustrated with a combined polymer-liquid crystal detection system for amines. Also described is the detection of liquid droplets by utilizing changes in the birefringence of polycarbonate membrane filters.     

Detection and Spectrophotometric Determination of Microgram Quantities of Ethylenediaminetetraacetic Acid with Phosphomolybdic Acid

Abstract

A simple, rapid and accurate method for the detection and determination of microgram quantities of EDTA is based on the absorbance of the complex formed by its reaction with phosphomolybdic acid at pH 2. Absorbance is measured against a phosphomolybdic acid reference solution at a wave length of 690 am. The effect of time, temperature and amount of phosphomolybdic acid is studied and optimum operating conditions established. Beer's law is obeyed in the concentration range 18.6–186.0 μg ml^?1 of EDTA. Its detection limit is 18.6 μg in the solution phase and 3.72 μg in the resin phase. The relative standard deviation is ±0.445 μg. Ion exchange resin beads act as a catalyst and detection medium to improve the sensitivity and selectivity of the test.     

Electron Capture Gas Chromatography of Tertiary Amines After a Demethylation Reaction to Secondary Amines

Abstract

A gas chromatographic method for the determination of tertiary amines in micro- and nanogram amounts is presented. The tertiary amine is reacted with ethyl chloroformate to form a urethan, which is cleaved to a secondary amine. This is transformed to heptafluoro-butyramide, which makes quantitative determination with electron capture detection possible. The yields of the secondary amines for two tertiary amines were 60 and 75%. By use of internal standard technique in the entire reaction recoveries of 97.6 ± 2.2% at the 100 μg level and 100 ± 4% at the 200 ng level were obtained.     

The identification of aliphatic amines in air as their benzamides by paper chromatography

A method is described for the separation of amines as their benzamides by paper chromatography. Data are given on separations in two systems. Homologous benzamides from C₁ to C₁₀ are best separated on S & S ₂₀₄₅a paper while C₁₀ and C₁₂ are separated on 2045a paper. When radio-carbon labelled benzamides were chromatographed and placed on x-ray film for eight to ten days with subsequent development of the radioautograph, the lower limit of identification was found to be ca. 2.5 μg of each benzamide. The results of analysis for amines in two samples of air particulate matter, and one of atmospheric vapors are presented.     

Continuous Determination of Free Cyanide by Means of Membrane Diffusion of Gaseous HCN and An Electrode Indicator Technique

Abstract

A continuous measurement system for free cyanide has been developed based on the principle of diffusion across a gas-permeable membrane to affect the separation of hydrogen cyanide from the acidified sample solution. The cyanide absorbed in the alkaline indicator solution is subsequently analyzed by an indirect technique using a silver ion-selective electrode. In the concentration range of 30 to 400 μg CN^?/L, the accuracy and precision of this method is approximately two percent. The detection limit of this system is approximately 0.5 μg CN^?/L.     

Spectrofluorimetric Evaluation of Total Aliphatic and Aromatic Amines in Well Waters and Wastewaters

Abstract

A simple and rapid spectrofluorimetric method is described for the determination of aliphatic and aromatic amines on the basis of ammonia and aniline, respectively. Aromatic amines in samples were reacted at pH 5.5 with fluram immoblised on an Octadecylsilane Solid Phase Extraction (ODS-SPE) cartridge. The produced pyrrolinones were adsorbed on SPE and separated from the aliphatic amines. Analysis of these compounds was carried out by elution of SPE with 1 ml Tetrahydrofuran (THF) and determination of fluorescence intensity at excitation wavelength 400 nm and emission wavelength 475 nm. Aliphatic amines after passing from SPE were collected and reacted with fluram at pH 9.2, and extracted into dichloromethane at pH 3 and quantitated fluorimetrically.

Linear dynamic ranges and detection limits (LOD) were 1–20, 0.43 mg 1^?1 and 1-200, 0.39 μg 1^?1 for ammonia and aniline, respectively. The proposed method was successfuly applied for the evaluation of these compounds in local well waters and municipality wastewaters.     

Measurement of Total Antimony in Marine Organisms and Waters by Stibine Generation and Atomic Absorption Spectrometry

Abstract

Antimony is reduced to stibine by sodium tetrahydroborate solution, passed through a heated silica tube and measured by atomic absorption spectrometry at 217.6 nm. Antimony is preconcentrated from water samples by lanthanum hydroxide precipitation. The detection limit is .0018 μg/ml and the rsd is 3.6% at the 0.050 μg/ml level. Interferences are discussed and the biological sample decomposition procedure evaluated. Typical results obtained for macroalgae, molluscs and fish in coastal waters are given.     

Chemiluminescence Flow Injection Analysis of Menadione Sodium Bisulfite Based on Luminol Reaction

ABSTRACT

A chemiluminescence(CL) flow system is described for the determination of menadione sodium bisulfite based on its repression on the chemiluminescence(CL) emission produced upon mixing a hexacyanoferrate(III) solution with an alkaline luminol solution in the absence of co-oxidizer. The system responds linearly to menadione sodium bisulfite concentration in the range 0-1 μg/mL with a detection limit (3σ) of 0.01 μg/mL. Relative standard deviation (RSD) of 0.16% for 0.4 μg/mL menadione sodium bisulfite (n=11). The system has been successfully applied to the determination of menadione sodium bisulfite in tablets and injections.     

Determination of Mescaline in Hallucinogenic Cactaceae by Ion-Interaction HPLC.

Abstract

An ion-interaction HPLC method is developed for the determination of mescaline in some Cactaceae species, namely Gymnocactus beguinii, Echinocactus polycephalus, Coriphanta radians, Coriphanta scolymoides, Coriphanta palmeri, Lophophora williamsii and Trichocereus pachanoi.

Mescaline is characterized by hallucinogenic properties and can be prescribed as a psychodrug.

The method makes use of a C18-reversed-phase as the stationary phase and of a 5.0 mM aqueous solution of octylamine o-phosphate as the mobile phase, with spectrophotometric detection at 230 nm.

The method is sensitive (detection limit of 35 μg/L) and matrix interference-free.

The pretreatment of the sample is performed by grinding the fresh cactus and extracting the jelly pulp obtained either with a methanolic-ammonial solution or an aqueous solution buffered at pH 4.0 (phosphate buffer).

The average amounts of mescaline found in Lophophora williamsii and in Trichocereus pachanoi were respectively 2.55 mg and 3.10 mg/g of fresh cactus.     

Determination of Folic Acid in Commercial Diets by Anion-Exchange Solid-Phase Extraction and Subsequent Reversed-Phase HPLC

Abstract

Folic acid at the μ/g level is determined in total nutritional diets by concentration on disposable commercial anion exchange columns followed by elution with a concentrated salt solution and subsequent reversed-phase HPLC with absorbance detection at 365 nm. The method is specific for folic acid with respect to some known degradants and electrochemically generated oxidation products.     

Simultaneous Analysis of Pyridoxine and Melatonin in Tablet Formulation by Derivative Ultraviolet Spectroscopy

Abstract

A method for simultaneous analysis of pyridoxine and melatonin by second and third derivative UV - spectroscopy, the “zero - crossing” technique, is described. The determination has been carried out in 0.1 mol dm^?3 hydrochloric acid solution and the concentration range of 2 – 10 μg/ml pyridoxine and 0.5 – 3.5 μg/ml melatonin. Lower limits of detection at the 95% confidence level were 0.26 μg/ml for pyridoxine and 0.05μg/ml for melatonin The advantages of the proposed method include its application for the assay and in-vitro dissolution studies of pyridoxine and melatonin from two different tablet formulations.     

Preconcentration and Spectrophotometric Determination of Chromium (VI) and Total Chromium in Drinking Water by the Sorption of Chromium Diphenylcarbazone with Surfactant Coated Alumina

Abstract

A simple and inexpensive method for determining chromium (VI) in drinking water by spectrophotometry after preconcentration with sodium dodecyl sulphate (SDS) coated alumina column is described. Chromium(VI) is reacted with diphenylcarbazide (DPC) and the Cr-DPC complex is quantitatively adsorbed onto a SDS coated alumina column from 800 ml of sample solution. The complex is then eluted with a 8 ml mixture of methanol, acetone and hydrochloric acid and determined by spectrophotometry. Total chromium can be determined after oxidation of chromium (III) to chromium (VI) by KMnO₄. The relative standard deviation (10 replicate analyses) at the 10 μg l^?1 of chromium (VI) and 10 μg l^?1 of total chromium were 3.5% and 3.4% and corresponding limits of detection (based on 3 σ) were 0.040 μg l^?1 and 0.033 μg l^?1, respectively.     

Determination of Benzo(a)pyrene in Water by Synchronous Fluorimetry Following Preconcentration on Sephadex Gels

Abstract

Benzo(a)pyrene (BaP) which presents native fluorescence in solution has been determined in waters by synchronous solid-phase spectrofluorimetry. The relative fluorescence intensity of BaP fixed in Sephadex G-25 gel is measured after being packed in an 1-mm silica cell. Spectral characteristics of BaP-gel system are described. The applicable concentration range was 0.52–3.45 μg.L^?1 with a relative standard deviation of 1.2% and detection limit of 0.07 μg.L^?1. The method was applied to the analysis of waters with different provenances.     

Determination of aluminum and silicon in biological materials by inductively coupled plasma atomic emission spectrometry with electrothermal vaporization

An atomic emission spectrometric method is described for the determination of trace elements in microvolume samples especially of biological materials. Based upon the arrangement of a commercial electrothermal vaporizer and a 40-MHz inductively coupled plasma, the direct determination of aluminum and silicon in human body fluids such as urine and serum and aluminum in hemodialysis solution is performed. The instrumental system involves vaporizing the sample from a modified graphite electrode followed by atomization and excitation of the vapors in the ICP discharge. Compromise experimental conditions are reported and calibration functions compared. Limits of detection in 5-μl samples were 8 pg Al and 2.5 ng Si, and after preconcentration of Al with a poly(acrylamidoxime) resin, the detection limit was 1 pg Al. Recovery of 5 μg $\text{Si}\text{ml}$ and 10 ng $\text{Al}\text{ml}$ from aqueous and synthetic standards was 80–85% and 96–103%, respectively.     

Evaluation of Fluorescamine as a Phosphogenic Derivatizing Reagent of Primary Amines

Abstract

Fluorescamine has been shown to be a promising derivatizing reagent for the room temperature phosphorescence analysis of primary amino acids. The fluorescamine concentration used for derivatization in solution was 600 μg/ml and for direct derivatization, 1160 μg/ml. For derivatized primary amino acids the limits of detection were found to be between 0.8 ng and 2.9 ng with linear dynamic ranges between 2 and 3 orders of magnitude.     

Disposable Screen-Printed Electrodes (Spe) Mercury-Free for Lead Detection

ABSTRACT

Strategies to modify screen-printed electrodes (SPE) for lead determination are reported. Dithizone was mixed with graphite ink to obtain a modified screen-printed strip to detect ppb levels of lead(II) (detection limit 12 μg/l) using square wave anodic stripping voltammetry (SWASV). In addition, screen-printed electrodes were also modified by casting a few μl of a Nafion® solution onto the working electrode surface. In this case, ppb levels of lead were detected (detection limit 15 μg/1), using potentiometric stripping analysis (PSA). The addition of an ionophore to Nafion® polymer was also investigated, but this did not yield a significant improvement.     

Isolation of Glycoalkaloids with the Chromatotron and Their Determination by High-Performance Liquid Chromatography

Abstract

An extract of Solanum laciniatum leaves was fractionated with the Chromatotron. The glycoalkaloid fraction thus obtained was analyzed by reversed-phase HPLC. The load capacity of the Chromatotron with a 2-mm layer thickness is 600 mg (as determined with cholesterol) and the recovery of solasonine from the plant extract (as determined by HPLC) is 93–96%. The HPLC method permits the detection of as little as 1.5 μg solasonine or 3.5 μg solamargine with a linear detector response up to 375 μg for the former and 250 μg for the latter.     

HPLC Assay for S-2-(3-Aminopropylamino)ethyl Phosphorothioate (WR 2721) in Plasma

Abstract

A specific HPLC assay has been developed for determination of the radioprotective drug WR 2721. The method is based on precolumn derivatization of plasma with fluorescamine, separation with a C-18 cartridge and detection by fluorescence. An external standard was used for calibration, and values were adjusted based upon recovery of added ¹⁴C-labeled WR 2721. WR 2721 had a retention time of about 13 minutes using a mobile phase of acetonitrile/water (22:78), 0.01 M in dibutylammonium phosphate, at a flow rate of 2 mL/min. Sensitivity of the assay was characterized to 2 μg/mL, and detector response was linear over the range of 2 to 1100 μg/mL. The assay requires 90 μL of plasma and has a total chromatography time of about 45 minutes. 2-(3-Aminopropylamino)ethanethiol (WR 1065) and bis- [2- (3-aminopropylamino)ethyl]disulfide (WR 33278), metabolites of the drug, and a variety of primary amines were shown not to interfere with the assay. Suitability of this assay for pharmacokinetic studies was demonstrated in preliminary experiments with a beagle dog.     

New Rapid Assay for Nafcillin by Spectrofluorimetry in Pharmaceutical Dosage

Abstract

A method for the spectrofluorimetric determination of nafcillin is proposed (λ_ex = 226 nm, λ_em = 366 nm), for concentrations between 0.10 and 1.0 μg mL^?1. The method was performed in ethanol/water medium (30% V/V), at apparent pH 6.0 provided by adding of phosphate buffer solution with pH = 6.20.

The obtained values of detection and determination limits are 0.016 and 0.054 μg mL^?1, respectively.

The method was successfully applied to assay a commercial injection containing nafcillin sodium monohydrate.