Chemiluminescence Determination of Organophosphorus Pesticides Chlorpyrifos in Vegetable

Abstract

A novel chemiluminescence method for the quantitative assay of the organophosphorus pesticide chlorpyrifos in vegetable samples is presented. The determination is based on the reaction of chlorpyrifos with luminol-H₂O₂ in alkaline medium with sodium chloride being enhancer. Under the optimum conditions, the increased CL intensity was proportional with the concentration of chlorpyrifos in the range of 1.0 × 10^?8 g · ml^?1 ? 1.0 × 10^?6 g · ml^?1 and the detection limit was 3.5 × 10^?9 g · ml^?1 (3σ). The relative standard is less than 3.9% for 5.0 × 10^?7g · ml^?1 chlorpyrifos (n = 7). This method has been successfully applied to the determination of chlorpyrifos residue in vegetable sample. Further study was focused on the mechanism of chlorpyrifos and the possible mechanism was proposed.     

Simultaneous Determination of Perphenazine and Amitriptyline by Derivative Spectrophotometry

Abstract

Two methods have been developed for the simultaneous determination of Amitryptiline and Perphenazine: the zero-crossing (I) and the derivative ratio spectrum (II) methods and both use the derivative spectrophotometry.

The methods have been applicable in the ranges of 1 to 30 μg·ml^?1 of Amitryptiline (I and II) and between 1 and 8 μg·ml^?1 and from 1 to 7 μg·ml^?1 of Perphenazine for the methods I and II respectively. The accuracy of the proposed methods have been studied and they have been used in the determination of Amitryptiline and Perphenazine in commercially available pharmaceuticals.     

Study on Chemiluminescence Assay of Surfactant PEG-400 Using Luminol–Hydrogen Peroxide System

Abstract

Based on the fact that nonionic surfactant polyethylene glycol-400 (PEG-400) catalyzed the chemiluminescence of luminol-H₂O₂ system, a novel and simple chemiluminescence method has been developed for the determination of PEG-400. Under the optimal conditions, the standard curve was Y = 198835X–2091.8, where the correlation coefficient (R) was 0.9999. The detection limit was 4 × 10^?5 g·ml^?1 PEG-400 and the linear range was 1.0 × 10^?4–4.0 × 10^?2g·ml^?1. The relative standard deviation was 3.2% at 2.0 × 10^?3 g·ml^?1 PEG-400 (n = 7). This method has been applied to the determination of PEG-400 in cosmetic samples with satisfactory results. Furthermore, the dynamics characteristic curve of PEG-400 in luminol-H₂O₂ system was compared to typical metallic ion and other surfactants. Moreover, the mechanism of the luminol-H₂O₂-PEG-400 chemiluminescence system was studied, assisted by fluorescence spectra and UV spectra.     

Spectrophotometric Determination of Some Fluoroquinolone Derivatives in Dosage Forms and Biological Fluids Using Ion‐Pair Complex Formation

Abstract

A simple, rapid, sensitive, and reproducible procedure for assaying norfloxacin (NOR), ciprofloxacin (CIP), and ofloxacin (OFL) was investigated. The procedure is based on the reaction of selected drugs with Sudan II (I), Congo red (II), and Gentian violet (III) in universal buffer to give soluble ion‐pair complexes. The effects of various parameters have been studied. Beer's law plots were obeyed in the concentration ranges 0.5–11 µg ml^?1, whereas Ringbom optimum ranges were 0.7–9.5 µg ml^?1. The apparent molar absorptivity (6.4×10⁴ L mol^?1 cm^?1), Sandell sensitivity (4.99 ng cm^?2), detection (0.13 µg ml^?1), and quantification (0.44 µg ml^?1) limits were calculated. The relative standard deviation for ten determinations, for samples containing 4.0 µg ml^?1, was found to be 1.40%. The influence of commonly employed excipients in the determination of the studied drugs was examined. There was no interference from degradate product results from thermal and hydrolytic treatments. The results obtained by the proposed procedure were statistically validated. The developed procedure was successfully applied to the determination of the studied drugs in dosage forms and biological fluids.     

Determination of tin in indium by neutron activation with pre-irradiation separation

A method has been developed for chemical control of a short-lived radiopharmaceutical,⁵²Fe. The optimum conditions have been investigated for the simultaneous determination of microgram amounts of nickel, iron and chromium in an admixture. The method developed is applicable for the determination of 0.01 to 20 μg·ml^?1 of nickel, 0.01 to 50 μg·ml^?1 of iron and 0.05 to 50 μg·ml^?1 of chromium. A study has been made of the mutual interference of these elements at different concentrations, and also of the interference by various other cations and anions. A list has been given of the other elements that can be analysed using the supporting electrolyte. A method of routine analysis is described.     

Spectrophotometric study of the reaction of bismuth with bromopyrogallol red in the presence of tensides: The determination of bismuth and EDTA

The formation of the complex between bismuth and bromopyrogallol red in the presence of cationogenic tensides CPB or Septonex was studied. Optimal conditions for this reaction were found and a new spectrophotometric method was developed for determining bismuth in the concentration range 0.2–5.5 μg · ml^?1. On the basis of the reaction of Bi with EDTA, a new method was developed for the indirect determination of EDTA in the concentration range 0.2–6.0 μg · ml^?1.     

Spectrophotometric and Spectrofluorometric Determination of Heptaminol and mexiletine in Their Dosage Forms

Abstract

Two simple, rapid specific methods were developed for the determination of heptaminol and mexiletine and their dosage forms. The methods are based on the reaction of either heptaminol or mexiletine with acetylacetone-formaldehyde reagent to give a yellow chromophore measurable spectrophotometrically at 344 or 338 nm or flurometrically at 480 nm for heptaminol and mexiletine, respectively. The color was stable for at least 1/2 h. Beer's law was valid within a concentration range of 15–30 and 8–20 μg ml^?1 spectrophotometrically and 0.2–0.8 and 0.4–1.0 μg ml^?1 fluorometrically for heptaminol and mexiletine, respectively.     

Fluorescent Complexes of Nucleic Acids/8-Hydroxyquinoline/Lanthanum(III) and the Fluorometry of Nucleic Acids

Abstract

The ternary fluorescent complexes of nucleic acids/8-hydroxyquinoline/ lanthanum (III) were studied. Nucleic acids in the study involve natured and thermally denatured calf thymus DNA, fish sperm DNA and yeast RNA. In the range of pH 8.0–8.4 (controlled by NH₃-NH₄Cl buffer) ternary fluorescent complexes are formed which emit at 485.0 nm for calf thymus DNA and at 480.0 nm for yeast RNA (when excited at 267.0 nm) and emits at 483.0 nm for fish sperm DNA when excited at 265.0 nm. Based on the fluorescence reactions sensitive fluorometric methods for nucleic acids were proposed. Using optimal conditions, the calibration curves were linear in the range of 0.4–3.6 μg˙ml^?1 for calf thymus DNA, 0.4–4.0 μg-ml^?1 for fish sperm DNA and 0.4–4.0 μg˙ml^?1 for yeast RNA, respectively. The limits of determination (3σ) were 0.076 μg˙ml^?1 for calf thymus DNA, 0.068 μg˙ml^?1 for fish sperm DNA and 0.329 μg˙ml^?1 for yeast RNA, respectively. Five synthetic samples were determined with satisfaction.

     

Comparison of Ion-Pairing and Reversed Phase Liquid Chromatography in Determination of Sulfamethoxazole and Trimethoprim

Abstract

Two simple, rapid, and sensitive HPLC methods have been developed for the simultaneous determination of sulfamethoxazole and trimethoprim in their pure and dosage forms, one utilizing reversed phase HPLC and the other ion-pair HPLC. In the reversed phase HPLC method (A) the mobile phase consists of 0.05% aqueous solution of formic acid with pH adjusted to 4.5±0.2 with triethylamine : acetonitrile:tetrahydrofuran 50 : 49 : 1 (v/v), and the mobile phase pumped at flow rate of 1.0 ml min^?1. An Appolo LC18 column (5.0 µm), 250 mm length × 4.6 mm diameter, was utilized as the stationary phase. Detection was affected spectrophotometrically at 254 nm. In the ion-pair HPLC method (B) the mobile phase consisted of methanol : buffer 35 : 65 (v/v) with the buffer composed of potassium dihydrogen phosphate 0.3 M and sodium heptan sulfonic acid 5.0 mM. To 500 ml of buffer was added 2.0 ml triethylamine, and then the pH was adjusted to 5.0 with phosphoric acid, and the mobile phase was pumped at a flow rate of 1.2 ml min^?1. A Hypersil C₁₈ column (5.0 µm), 150 mm length × 4.6 mm diameter, was utilized as the stationary phase. Detection was affected spectrophotometrically at 254 nm. Linearity ranges for sulfamethoxazole and trimethoprim were 1.0–110 and 1.5–98 µg ml^?1, respectively, with method A and 0.5–100 and 1.0–125 µg ml^?1, respectively, with method (B). Minimum detection limits obtained were 0.1969 and 0.3451 µg ml^?1 for sulfamethoxazole and trimethoprim, respectively, with method A, and 0.1377 and 0.2454 µg ml^?1 with method (B). The proposed methods were further applied to the analysis of tablets containing the two drugs, and the results were satisfied.     

Post‐chemiluminescence Method of the Determination of Loperamide Hydrochloride in Human Plasma and Pharmaceutical by Using Dichlorofluorescein as Chemiluminescence Reagent

Abstract

A post‐chemiluminescence (PCL) was observed when loperamide hydrochloride solution was injected into the reaction mixture after the finish of CL reaction of alkaline N‐Chlorosuccinimide (NCS) and dichlorofluorescein. Based on this phenomenon, a simple, sensitive and fast flow injection PCL method was established for the determination of loperamide hydrochloride. The possible mechanism for the PCL reaction was discussed via the investigation of the CL kinetic characteristics, the CL spectra, the fluorescence spectra. The PCL intensity responded linearly to the concentration of loperamide hydrochloride in the range 8.0×10^?10 to 6.0×10^?7 g · ml^?1 with a linear correlation of 0.9995. The detection limit was 4×10^?10 g · ml^?1. The relative standard deviation was 2.4% for 4.0×10^?8 g · ml^?1 loperamide hydrochloride (n=11). This method has been applied to the determination of loperamide hydrochloride in human plasma and pharmaceutical samples with satisfactory results.     

Determination of Morestan Residues in Water and Foodstuffs by Transmitted Room Temperature Solid Phase Spectrophosphorimetry

Abstract

A method for the determination of the pesticide morestan by means of transmitted room temperature solid phase spectrophosphorimetry has been developed. The method is based on the native phosphorescence showed by the morestan when it is fixed in a Whatman No 4 paper as a solid support. The excitation and emission wavelengths were 362 and 527 nm, respectively. The optimum phosphorescent emission was obtained when the delay time was 0.15 ms and the gate time 12.0 ms without need of a heavy atom. The linear dynamic range was between 0.1 and 1.0 μg.ml^?1, and the detection and quantification limits were 0.03 and 0.09 μg.ml^?1, respectively. The precision of the method, expressed as the relative standard deviation of ten samples at the 0.6 μg.ml^?1 concentration level, was 3.0%. The method was applied to the determination of the pesticide in different type of waters, potatoes and vegetables.     

Simultaneous Determination of Valsartan and Hydrochlorothiazide in Tablets by High-Performance Liquid Chromatography

ABSTRACT

A method for the simultaneous determination of valsartan and hydrochlorothiazide in tablets is described. The procedure, based on the use of reversed-phase high-performance liquid chromatography, is linear in the concentration range 5.0-10.0 μg ml^?1 for valsartan and 0.5-2.0 μg ml^?1 for hydrochlorothiazide, is simple and rapid and allows accurate and precise results. The limit of detection was 1.0 μg ml^?1 for valsartan and 0.05 μg ml^?1 for hydrochlorothiazide.     

A New Spectrophotometric Method for the Determination of Arsenic in Environmental and Biological Samples

Abstract

A simple and selective spectrophotometric method has been developed for the determination of trace amounts of arsenic using azure B as a chromogenic reagent. The proposed method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine. The liberated iodine bleaches the violet color of azure B and is measured at 644 nm. This decrease in absorbance is directly proportional to the As(III) concentration, and Beer's law is obeyed in the range 0.2–10 µg ml^?1 of As(III). The molar absorptivity, Sandell's sensitivity, detection limit, and quantitation limit of the method were found to be 1.12×10⁴ l mol^?1cm^?1, 6.71×10^?3 µg cm^?2, 0.02 µg ml^?1 and 0.08 µg ml^?1, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples.     

Catalyzed Determination of Glucose with a Mimic Enzyme Constructed of Bis‐[‐6‐O‐(‐β‐ethyloic‐butanedioic Acid‐1,4‐ester‐4‐)]β‐Cyclodextrin · Fe3+

Abstract

Catalyzed determination of glucose with mimic glucose oxidase is constructed by the reaction of β‐cyclodextrin, maleic anhydride, and chloroacetic acid with iron trichloride in hydrogen peroxide. The method is simple and convenient, and sensitivity and repeatability are ideal. Beer's law is obeyed in a concentration range of 30–197 µg · ml^?1 glucose with an excellent correlation coefficient (r=0.9994), while the detection limit is 4.10 µg · ml^?1, the RSD is 0.98% (n=8). The recovery of sample is 95.8–103.1%.     

Study on the Interaction between a Novel Ionic Liquid Probe and Anionic Surfactants Using Resonance Light Scattering Spectra and Its Analytical Application

The interaction between anionic surfactants (AS) and 1‐hexadecyl‐3‐methylimidazolium bromide [C₁₆mim]Br was studied by using resonance light scattering (RLS) technique, UV‐Vis spectrophotometry and fluorometric methods. In Britton Robinson (BR) buffer (pH 6.0), [C₁₆mim]Br reacted with AS to form supermolecular complex which resulted in enhancement in RLS intensity. Their maximum RLS wavelengths were all at 390 nm. Some important interacting experimental variables, such as the solution acidity, [C₁₆mim]Br concentration, salt effect and addition order of the reagents, were investigated and optimized. Under the optimum conditions, quantitative determination ranges were 0.001–7 μg·mL^?1 for dodecyl sodium sulfate (SDS), 0.001–6 μg·mL^?1 for sodium dodecylbenzene sulfonate (SDBS) and 0.005–7 μg·mL^?1 for sodium lauryl sulfonate (SLS), respectively, while the detection limits were 1.3 ng·mL^?1 for SDS, 1.0 ng·mL^?1 for SDBS and 5.1 ng·mL^?1 for SLS, respectively. Based on the ion‐association reaction, a highly sensitive, simple and rapid method has been established for the determination of AS.     

Use of diode-array detectors for the simultaneous spectrophotometric determination of calcium and magnesium by flow injection

A method for the simultaneous flow injection spectrophotometric determination of calcium and magnesium with Arsenazo III based on the use of diode-array detector and merging zones is described. The method is applicable to the resolution of mixtures in which the chromogenic reagent has a high absorbance and its spectrum strongly overlaps those of its complexes. In resolving the mixtures, the excess reagent is considered as another component. Quantitation is based on the normal absorbance and first-derivative absorbance spectra. The method is applied to 0.2–1.5 μg ml^?1 Ca and 0.1–1.0 μg ml^?1 Mg. The analysis rate is 50 h^?1.     

Cathodic stripping voltammetry of pipemidic acid and ofloxacin in pharmaceutical dosages and human urine

Sensitive cathodic stripping voltammetric methods have been developed for two quinolone antibacterial drugs, pipemidic acid (PIP) and ofloxacin (OFL) using hanging mercury drop electrode as working electrode vs. Ag/AgCl reference electrode. The methods were developed for the determination of drugs individually as well as simultaneously. 0.1 M and 0.01 M hydrochloric acid was used as medium for PIP and OFL, respectively, 0.1 M potassium chloride was used as base electrolyte. Reduction waves were observed for PIP within ?700 mV to ?800 mV and for OFL within ?1100 mV to ?1200 mV. Linear calibration ranges for PIP and OFL were observed within 10–100 μg ml^?1 with detection limits of 50 ng ml^?1 and 1 μg ml^?1, respectively. Relative standard deviations (RSD) for the analysis of 10 gµg ml^?1 of PIP and OFL (n = 6) were 0.5% and 1.4%, respectively. The presence of glucose, lactose, sorbitol, gum arabic, starch, magnesium stearate, methylparaben and propylparaben did not affect the determinations of both PIP and OFL. The methods were used for the analysis of pharmaceutical preparations and the results indicated relative deviation of 0.5–5.5% from labeled values with RSD within 0.49–2.5%. PIP and OFL could also be determined simultaneously, and were determined from spiked human urine.     

Novel Method for Selective Spectrophotometric Determination of Titanium(IV) with Water Extract of Slippery Elm Leaf as a New Reagent

Abstract

A novel spectrophotometric method for the determination of titanium(IV) by using a new reagent, water extract of slippery elm leaf is developed. In 0.05 M hydrochloric acid, titanium(IV) reacts with this reagent to form a yellow product. The formed product shows maximum absorbance at 415 nm with a molar absorptivity value of 0.68×10⁴ l mol^–1 cm^–1 and the method was linear in the 0.2–6 µg ml^?1 concentration range. The detection limit value was found to be 0.0131 µg ml^?1. The proposed method was simple, low cost, selective, and sensitive. It was applied to the analytic samples with satisfactory results.     

Spectrophotometric and First Derivative Spectrophotometric Determination of Magnesium with 1-Hydroxy-2-Carboxyanthraquinone

Abstract

1-Hydroxy-2-carboxyanthraquinone reacts with magnesium in ethanol-water mixtures to form a red complex having an absorption maximum at 490 nm in alkaline medium. A detailed study of the characteristics of this complex has been carried out and a spectrophotometric method for the determination of magnesium at the 0.4–4.0 μg ml^?1 level is proposed. The method has been sensitized by employing first derivative spectrophotometry. By the use of the derivative approach magnesium can be determined between 0.08–0.40 μg ml^?1. Statistical analysis of the results is also described.     

Spectrophotometric determination of iron(III) with EDTA tetrahydrazide

The tetrahydrazide of ethylenediamine tetraacetic acid (NH₂NH)₄-EDTA was synthesized from the EDTA ester and hydrazine hydrate in ethanolic solution, the resulting (NH₂NH)₄-EDTA being recrystallized in 60% ethanol. When the spectrophotometric study of the iron(III) (NH₂NH)₄-EDTA complex in aqueous solution was made two absorption maxima at 530 and 450 nm at pH 4.5 and 11.0, respectively, were found. Beer's law is obeyed in the range 1.0–20.0 μg Fe(III) ml^?1 at 530 nm and pH 4.5 and 0.5–12.0 μg Fe(III) ml^?1 at 450 nm and pH 11.0, the molar absorptivities being 1.95 × 10³ 1 mol^?1 cm^?1 at 530 nm and 3.35 × 10³ 1 mol^?1 cm^?1 at 450 nm, respectively. The Ringbom optimal interval falls between about 3 and 18 μg Fe(III) ml^?1 at 530 nm and about 2–14 μg Fe(III) ml^?1 at 450 nm. The reaction between the metal and the ligand was also investigated. The method has been successfully applied to the determination of iron in talcs.