Sequential Extraction-Spectrofluorimetric Determination of Lead and Mercury Using Cryptand Ethers

Abstract

A spectrofluorimetric method for the determination of ultratrace amounts of lead and mercury is described based on the sequential extraction of the ternary ion-association complexes formed between the cation, a cryptand as the ligand and eosin as counter ion. A linear working range from the detection limit (9 ng/ml) to 250 ng/ml of lead and 12 ng/ml of mercury was obtained.

The relative standarddeviation was 3.5 % – 2.1 %. We propose that this method could be used routinely to control lead and mercury simultaneous.     

Separation and Removal of Mercury(II) from Water Samples Using (Acetylacetone)‐2‐Thiol‐Phenyleneimine Immobilized on Anion‐Exchange Resin Prior to Determination by Cold Vapor Inductively Coupled Plasma Atomic Emission Spectroscopy

Abstract

(Acetylacetone)‐2‐thiol‐phenyleneimine (H₂L) immobilized on an anion‐exchange resin (Dowex) was used for separation and removal of mercury from natural water samples and for preconcentration prior to its determination by cold vapor inductively coupled plasma atomic emission spectroscopy. The metal was eluted from the column using a solution of 10% thiourea in 0.1 M HCl. The modified resin is higly selective with an exchange capacity of 1.60 mmol g^?1. Various parameters like pH, column flow rate, and desorbing agents are optimized. The proposed method has a linear calibration range of 15–1000 ng/ml Hg(II), with a relative standard deviation at the 15 ng/ml level of 3.5%. The precision of the method (evaluated as the relative standard deviation obtained after analyzing six series of five replicates) was ±4.2% at the 50 ng/ml level of Hg(II). The method has been used for routine determination of trace levels of mercury species in natural waters. The potential application of modified resin for the removal of mercury(II) from two natural water samples (top water and lake water) spiked with 50 ng/ml of mercury (II) was studied by ICP‐AES, and the results proved that excellent percent extraction of mercury(II) from both natural water samples was obtained by column method using modified resin.     

Spectrophotometric Determination of Mercury(II) by Flow Injection Analysis

Abstract

A new spectrophotometric FIA method for total mercury determination in water is proposed for the 5-40ng ml range. The method is based on the inhibitory effect of Hg(II) in the catalytic action of iodides on the As(III)-Ce(IV) reaction. By means of preconcentration techniques using KMnO₄ traps, ppt levels of mercury in water can be detected.     

Determinated of Trace Amounts of Mercury by Non-Disperse Atomic Fluorescence Method

Abstract

A rapid and sensitive cold vapor method for the determination of trace mercury by non-disperse atomic fluorescence measurement is proposed. Mercury vapor generated from solution was swept into the nozzle (the funnel type of glass tube) by nitrogen, and the atomic fluorescence (AF) of mercury in the gas mixture was detected by a non-dispersive AF method using a solar-blind photomultiplier. The detection limit obtained was 0.5 ng per 5 ml sample solution.     

Voltammetric Determination of Aluminium in Haemodialysis Concentrates Using the Adsorption of the Al(III)-1,2-Dihydroxyantraquinone-3-sulphonic Acid Complex in Presence of Calcium

Abstract

This paper describes a method for the quantitative determination of aluminium in haemodialysis concentrates, based on the adsorption on a static mercury drop electrode of the Al-1,2 dihydroxyantraquinone-3-sulphonic acid complex. The signal was notably increased in presence of calcium. The electrolysis was carried out at -0.900 V. After 60 sec the aluminium contents were measured by differential pulse voltammetry. In these conditions aluminium can be determined in the range 0.65–38 ng/ml with a detection limit (3[sgrave]) of 0.20 ng/ml. The relative standard deviation was in all instances less than 2.1%.     

Trace Level Analysis of Mercury Using Urease in Combination with an Ammonia Gas Sensitive Semiconductor Structure

Abstract

A method for the determination of mercury(II) ions at trace levels is described. The method is based on the profound inhibitory effect of mercury on the enzyme urease. The activity of the enzyme was determined by the rate of ammonia produced from urea as followed by an ammonia gas sensitive iridium thin metalfilm-oxide-semiconductor (IrTMOS) structure. Two systems were investigated. For the initial urease activity studies, a simple microcell was used. Also, a test plate, containing dry reagent strips with all necessary chemicals was developed, making the analytical procedure very simple to perform. The test volume applied was 2 μl and the sensitivity to standards of mercury(II) ions is at least 0.005 μM (1.0 ng/ml). One sample could be analyzed in less than 8 minutes. Furthermore, the kinetics of sensor response versus enzyme activity is discussed.     

Determination of Trace Amounts of Acetaldehyde Using a Novel Chemiluminescence Reaction

Abstract

The chemiluminescent reaction of iso-propyl alcohol with C10^?-H₂O₂ is enhanced by acetaldehyde. This provides a new method for the determination of trace amounts of acetaldehyde. The detection limit is 0.08ng/ml acetaldehyde and the linear dynamic range is 0.5ng/ml to 1000 ng/ml. The method results in good selectivity and has been satisfactorily applied to the determination of traces of acetaldehyde in waste water samples.     

Voltammetric Determination of Indigo Carmine and Amaranth on a Silver-Based Mercury Film Electrode

Abstract

The voltammetric behavior of indigo carmine and amaranth on silver-based mercury film electrodes was studied. At pH 4, reduction current peaks were observed at potential ?0.11 V (indigo carmine) and ?0.24 V (amaranth), respectively. The system showed a linear response to both of the food colorants in a concentration range of 0 to 100 ng/ml. Detected at different reduction potentials, indigo carmine and amaranth could be determined separately without interfering with each other. This method demonstrated a better reproducibility and longer life time than the existing techniques.     

Determination of Formaldehyde in Waste Water by Lucigenin Chemilummescence

Abstract

A chemiluminescence analysis has been developed for the determination of formaldehyde based on its inhibition of the chemiluminescence reaction of lucigenin-C10^?-H₂o₂. The method is sensitive, convenient and selective with a detection limit of 0.05ng/ml. The linear dynamic range is 1.0ng/ml to 0.1 μg/ml. The variation coefficient of ten determinations for 2.Ong/ml formaldehyde is 1.2%. Applications to the trace determination of formaldehyde in industrial waste waters are discussed.     

Dosage Du Mercure Dans Les Eaux Naturelles Non Ou Peu Polluees Apres Extraction Par Le Systems Pyrrolidinedithiocarba -Mate-Carbonate De Propylene

Abstract

A procedure for determination of mineral mercury in soft water and sea water is described for the concentrations in the range 5–500 ng. 1^?1. This method involves formation of the mercury-pyrrolidinedithiocarbamate complex which is extracted by propylene carbonate. The extracted mercury is reduced in this solvent by stannous chloride and quickly entrained by nitrogen. The amount of mercury is determined by atomic absorption spectrophotometry at 253. 7 nm.     

Determination of Traces of Mercury (II) and Phenylmercury by Direct Polyurethane foam Thin-Layer Spectrophotometry

Abstract

The determination of mercury and phenylmercury in the ppb concentration range using polyurethane foam (PUF) thin-layer spectrophotometry has been described. Sorption of mercury and phenylmercury into foam parallepiped loaded with diphenylthiocarbazone (dithizone) contributed to considerable improvement in the absorbance value of the colored species, being concentrated about 140 times.

The method allowed the achievement of satisfactory results, the detection limits are 5 and 10 μg per litre for mercury and phenylmercury, respectively, for 100ml sample volume. The average recovery from tap water amounts to 100% for mercury and 96.6% for phenylmercury.     

Determination of the New Ace-Inhibitor Quinapril and Its Active Metabolite Quinaprilate in Plasma and Urine by High-Performance Liquid Chromatography and Pre-Column Labelling for Fluorescent-Detection

Abstract

A sensitive and selective method for the determination of quinapril and its active metabolite quinaprilate in human plasma and urine is described. The method is based on isolation using C18 Bond Elut cartridges, pre-column derivatization with 9-anthryldiazo-methane and purification of the reaction mixture on CBA columns followed by reversed-phase high performance liquid chromatography with fluorometric detection. Calibration curves were linear between 20 ng and 1000 ng/ml of plasma (100-2000 ng for urine) for both substances, the lower limit of detection being 5-10 ng/ml.

The present assay procedure has been applied to monotoring plasma and urine concentrations in several pharmacokinetic studies in humans.     

Improved High Pressure Liquid Chromatographic Method for Phenylpropanolamine in Human Plasma

Abstract

A high-pressure liquid chromatographic analysis of phenylpropanolamine in plasma following extraction, back extraction and pre-column derivitization with O-phthalaldehyde is presented. The method is improved by the use of phenylethanolamine as internal standard. Using fluorescence detection, the method is sufficiently sensitive to quantitate 5 ng/ml in 0.5 ml plasma with a standard error of estimate of 2.7 ng/ml when calibrated over the O to 240 ng/ml range. Analysis of over 2000 clinical samples have shown the method to be highly specific and reliable.     

High Performance Liquid Chromatoraphic Determination of R-831, A New Antiallergic Agent,in Dogs and Humans

Abstract

A simple, selective and sensitive HPLC method has been developed to measure R-831 levels in dogs and humans. It is an internal standard technique with a single step extraction and one wash. Samples are chromatographed on a reversed-phase system with ultraviolet detection. The lowest detectable concentration for plasma is 25 ng R-831/ml with a 1 ml sample and the linear range is 25–8000 ng R-831/ml. The lowest detectable concentration for urine is 250 ng R-831/ml with a 0.1 ml sample and the linear range is 250–8000 ng R-831/ml. This method has been used to quantitate levels of R-831 in bioavailability and toxicity studies in dogs, and in pharmacokinetic and efficacy studies in humans.     

HPLC Measurement of Cyclosporine in Blood Plasma and Urine and Simultaneous Measurement of its Four Metabolites in Blood

Abstract

A high performance liquid chromatographic assay has been developed for the estimation of cyclosporine and its four major metabolites in blood and for cyclosporine alone in plasma and urine samples. This assay employs a rapid and very reproducible solid-liquid extraction system. Isocratic chromatographic conditions allow the simultaneous measurement of cyclosporine and its four major metabolites in blood. The method is linear up to 2500 ng/ml and the minimum quantifiable limit for cyclosporine is 30 ng/ml, when 1 ml of sample is analyzed.     

Revised HPLC Determination of Atenolol in Plasma and Urine

Abstract

An HPLC method for analysis of atenolol in human plasma and urine is presented. Based on alkaline extraction, acid backextraction and reverse phase ion-pair chromatography this method is quite specific for atenolol. For a 0.5 ml plasma sample the sensitivity ranges from 20 ng/ml in fasted healthy volunteers to 50 ng/ml in various groups of patients. A sensitivity in urine of 1.0 mcg/ml was sufficient for all samples studied. As presented this method has been used in several clinical pharmacokinetic studies involving hundreds of samples.     

Routine Determination of a New 1–4 Dihydropyridine,Oxodipine, in Human Plasma by High Performance Liquid Chromatography with Electrochemical Detection

Abstract

A rapid, specific and reproducible high-performance liquid chromatographic routine assay with electrochemical detection was developed for the determination of Oxodipine in human plasma.

After extraction at alkaline pH by cyclohexane, Oxodipine and its internal standard were chromatographied on a reversed-phase column.

Calibration curves were linear over a concentration range of 1–50 ng/ml with relative errors within-day or between-day not exceeding 8% at any level.

The limit of detection was 30 pg injected based on a signal-to- noise ratio of 7. However, the reliable limit of quantification was 1 ng/ml using 1 ml of human plasma.

A dual-electrode coulometric detector was operated in a screening mode of oxidation, providing a greater specificity and reducing background noise.

This method allowed the complete follow-up of clinical pharmacokinetic studies and drug monitoring in patients.     

Electron Capture Gas Chromatography of Nitrazepam in Human Plasma as Methyl Derivative

Abstract

A method for quantitative determination of nitrazepam in human plasma in the range 5 - 100 ng/ml is presented.

Nitrazepam is extracted with benzene from plasma samples of 0.5 ml, methylated with methyl iodide and determined gas chromatographically with an electron capture detector of ⁶³Ni-type.

Acid dissociation constants of nitrazepam are determined and the partition properties studied with benzene, methylene chloride and diethyl ether as organic phases.

The selectivity of the method with respect to the metabolites has been thoroughly studied.     

Rapid Determination of Bupropion in Human Plasma by High Performance Liquid Chromatography

Abstract

A high performance liquid chromatographic (HPLC) technique has been developed for the determination of bupropion hydrocloride (Bup) in human plasma, using a reversed-phase method, with UV detection at 250 nm.

The internal standard 5-(P-methylphenyl)-5-phenylhydantoin (MPPH), was used as an aid to quantitation. The plasma was deprotemized with acetonitrile and the clear supernatant was directly injected in the chromatographic system. The lower limit of quantitation was 5.0 ng/ml using only 100 μl of plasma sample.

Linear regression analysis for the calibration plots obtained on five different days over a two-week period for the the two ranges used (10–250 ng/ml and 250–2000 ng/ml) in plasma indicated excellent linearity and reproducibility. The mean recovery of spiked Bup in plasma samples over the concentrations studied was found 96.5 ± 3.14%.

The method revealed that more than 30% of Bup was lost when the supernatant was stored at room temperature for 24 hrs.     

Indirect Mercury Speciation in Biological Tissues by Closed‐Vessel Microwave‐Assisted Digestion and Flow‐Injection Cold‐Vapor Atomic Fluorescence Detection

Abstract

A simple and rapid method based on closed vessel microwave‐assisted extraction was developed to determine total, inorganic mercury and organomercury in biological tissues. Total mercury was extracted using HNO₃:H₂O₂ (4:1) mixture. In a separate subsample, extraction of mercury species was carried out with tetramethylammonium hydroxide (TMAH). The total and inorganic mercury analyses were carried out by flow‐injection cold‐vapor atomic fluorescence spectrometry (FI‐CV‐AFS). The organomercury concentration was calculated by difference. Considering a sample amount of 0.2 g, the detection limits were 4 and 26 ng/g for total and inorganic mercury, respectively. The accuracy of the procedures was checked by analyzing certified reference materials and recovery studies of spiked fish tissues.