Highly Sensitive Determination of Traces of Co(II) in Pharmaceutical and Urine Samples Using Kinetic–Spectrophotometric Method

Abstract

A high sensitive, accurate and simple kinetic method has been developed for determination of trace of Co(II) ions, based on its strongly catalytic effect in the reaction oxidation of disodium-6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphtalenesulfonic acid (artificial color, Sunset Yellow FCF, E110 in text selected as SY) by hydrogen peroxide in borate buffer at pH of 9.5, by monitoring the rate of disappearance of SY. Reaction rate was monitored spectrophotometrically, at λ_max of the SY at 478.4 nm. The optimum operating conditions regarding reagents concentration and temperature were established. The tangent method was adopted for constructing the calibration curve, which was found to be linear over the concentration range 1.18–17.67 ng ml^?1 and 17.67–58.90 ng ml^?1 of Co(II). The limit of detection (3σ) is 0.15 ng ml^?1, and limit of quantification (10σ) is 0.5 ng ml^?1. The effects of the other ions on the reaction rate were determined for an assessment of the selectivity of the method. The developed kinetic procedure was successfully applied for the determination of Co(II) in pharmaceutical and urine samples. The unique features of this procedure are that the determination can be performed at room temperature, and the analysis time is short. The newly developed method is high sensitive, simple, inexpensive and efficient for use in the analysis of a large number of samples.     

Ultrasensitive Assay of Gatifloxacin at Picogram Level Based on its Enhancing Effect on the Myoglobin‐Luminol Chemiluminescence Reaction

Abstract

Picogram‐level gatifloxacin was determined based on its significantly catalyzed effect on myoglobin‐luminol chemiluminescence (CL) reaction in the flow injection system. The enhanced chemiluminescence intensity was linear with gatifloxacin concentration in the range from 50 ngl^?1–10 µg l^?1 (r²=0.9995), and the detection limit was 20 ng l^?1 (3σ). At a flow rate of 2.0 ml min^?1 for each line, a complete analytical process could be performed within 0.5 min, including sampling and washing, with a relative standard deviation of less than 4.0% (n=7). The proposed method was applied successfully in the determination of gatifloxacin in tablets, human serum and urine samples with the recovery from 97.4–104.5%.     

Determination of Puerarin in Pharmaceutical Injection by Flow Injection Analysis with Acidic Potassium Permanganate–Glyoxal Chemiluminescence Detection

Abstract

A simple flow injection chemiluminescence method with synergistic enhancement has been investigated for the rapid and sensitive determination of puerarin. The method is based on the enhancing effect of puerarin on the chemiluminescence emission generated by the oxidation of glyoxal with potassium permanganate in a sulfuric acid medium. The optimization of chemical variables influencing the chemiluminescence response of the method has been carried out by applying experimental design, using the proposed flow?injection manifold. Under the optimal conditions, the enhanced chemiluminescence intensity was linear with the concentration of puerarin over the range from 10.0 ng · ml^?1 to 7.0 µg · ml^?1 (R²=0.9972) with a detection limit (3σ) of 3.0 ng · ml^?1. At a flow rate of 3.0 ml · min^?1, a complete analytical process could be performed within 0.5 min, including sampling and washing, with a relative standard deviation of less than 3.0%. The proposed method was applied successfully in the assay of puerarin in pharmaceutical injection and human urine. The mechanism of chemiluminescence reaction was discussed briefly.     

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.     

LC Determination of Nosiheptide in Swine Kidney and Liver

A liquid chromatographic method was developed for determination of nosiheptide in swine kidney and liver. The tissue samples were extracted with acetonitrile and defatted with hexane. The analytes were determined at a fluorescence excitation/emission wavelength of 357/515 nm and with gradient elution program. The limits of detection and limits of quantification were 5 and 20 ng g^?1, respectively, for swine kidney and liver. The mean recoveries for nosiheptide in swine kidney and liver ranged from 70.3 to 97.4% with coefficients of variation below 11.3% at 20–100 ng g^?1 fortification levels.     

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.     

Abilities of Partial Least‐Squares (PLS‐2) Multivariate Calibration in the Analysis of Quaternary Mixture of Food Colors (E‐110, E‐122, E‐124, E‐131)

Abstract

Sunset Yellow (SY), Carmoisine (C), Ponceau 4R (P), and Patent Blue V (PB) are synthetic organic dyes which are under governmental regulations all over the world because of their toxicity and carcinogenicity.

In this study, a simple and fast analytical procedure was proposed for the simultaneous determination of food dyes (SY, C, P, and PB) in powder drinks by means the partial least‐square treatment of spectrophotometric absorbance between 450 –730 nm, taken at 10 nm intervals. The experimental calibration matrix was constructed with 27 samples. The concentration ranges considered were 2, 3, 4 µg · ml^?1 for SY, 7, 8, 9 µg · ml^?1 for C, 9, 10, 11 µg · ml^?1 for P, and 0.3, 0.4, 0.5 µg · ml^?1 for PB. The method was applied to the determination of dyes in different commercially available powder drinks. The results obtained by the application of the PLS‐2 method were statistically compared with those obtained by an HPLC method using the F and t tests. Very similar values were found by two methods. No time consuming pretreatment was needed and this method also provides rapid, accurate and economical analysis of these colors.     

Chlorodesmethyldiazepam Fluorimetric Determination in Pharmaceutical Formulations and in Aqueous Media

Abstract

A direct fluorimetric method for the determination of chlorodesmethyldiazepam was proposed. The fluorescence process was pH dependent. The dynamic range for the method was 1.6–12 µg ml^–1. A linear relationship between the fluorescence intensity and the concentration of chlorodesmethyldiazepam solution was obtained with r ² of 0.9958. The detection limit for the method was found to be 0.224 µg ml^–1. The method has successfully applied to the determination of chlorodesmethyldiazepam in pure, authentic, and aqueous samples.     

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.     

FLOW - Injection Determination of Traces of Sulfide by the Brilliant Green - Sulfide Reaction with Spectrophotometry Detection

Abstract

A flow injection system is proposed for the rapid and sensitive determination of trace amounts of sulfide based on the addition reaction of sulfide with Brilliant Green at pH 7 and 25 C°. The effect of important parameters, such as reagent concentration, pH, reagent flow rate, sample volume, temperature and length of the reaction coil are reported. Sulfide in the range of 40 - 2000 ng·ml^?1 can be determined at a rate of 40 ± 5 samples per hour. The limit of detection was obtained as 2.0 ng of sulfide. The relative standard deviation for the determination of 100 ng·ml^?1 of sulfide is 0.8%. A system is proposed for elimination of potential interferences. The method was applied to the determination of sulfide in synthetic samples and in spring water.     

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.     

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.     

A novel chemiluminescence reaction system for the determination of lincomycin with diperiodatonickelate(IV)

A sensitive and high selective chemiluminescence (CL) method was developed for the determination of lincomycin in acid medium using diperiodatonickelate as a reagent. The mechanism leading to luminescence is discussed by comparing the spectra of fluorescence and CL. Relative CL intensity is linear in the range from 8.0 ng mL^?1 to 1.0 µg mL^?1, the limit of detection is 2.5 ng mL^?1 (3σ), and the relative standard deviation is 4.0% at 0.1 µg mL^?1 of lincomycin (n?=?7). The method was successfully applied to the determination of lincomycin in injections, human urine, and in serum samples.     

Colorimetric Determination of Lead Using Gold Nanoparticles

A combined homogeneous assay and colorimetric determination method using gold nanoparticles was developed for rapid determination of lead(II) in contaminated natural waters. The presence of lead(II) in the colloidal gold suspension causes a change in the absorbance of the suspension. An increase in the absorption property at 595 nm is accompanied by a change in the size of the gold nanoparticles. High concentrations of lead cause aggregation of the gold colloids. Colloidal gold nanoparticles were synthesized using tannic acid as the reducing agent; this reagent allowed selective determination of lead in 10 µL of water, with a detection limit of 310 ng mL^?1 with an analysis time of 5 min. The coefficient of variation for lead(II) within the working range of the assay (520 ng mL^?1–13 µg mL^?1) varied from 1.3% to 9.2%. The limit of detection using this method with a sample volume of 50 µL was 60 ng mL^?1. The coefficient of variation for lead over the working range of the determined concentrations (80 ng mL^?1–25 µg mL^?1) varied from 0.2% to 9.3%, while the values for the inter-day assay (n = 8) were less than 10%. The method was employed for the analysis of river, lake, marsh, and spring water; the recovery of lead was determined to be 72.5%–130% for 10 µL of water and 93.6%–114.7% for 50 µL.     

Determination of Pantoprazole, Rabeprazole, Esomeprazole, Domperidone and Itopride in Pharmaceutical Products by Reversed Phase Liquid Chromatography Using Single Mobile Phase

A simple, sensitive, and precise high performance liquid chromatographic method for the analysis of pantoprazole, rabeprazole, esomeprazole, domperidone and itopride, with ultraviolet detection at 210 nm, has been developed, validated, and used for the determination of compounds in commercial pharmaceutical products. The compounds were well separated on a Hypersil BDS C18 reversed-phase column by use of a mobile phase consisting of 0.05 M, 4.70 pH, potassium dihydrogen phosphate buffer - acetonitrile (720:280 v/v) at a flow rate of 1.0 mL min^?1. The linearity ranges were 400–4,000 ng mL^?1 for pantoprazole, 200–2,000 ng mL^?1 for rabeprazole, 400–4,000 ng mL^?1 for esomeprazole, 300–3,000 ng mL^?1 for domperidone and 500–5,000 ng mL^?1 for itopride. Limits of detection (LOD) obtained were: pantoprazole 147.51 ng mL^?1, rabeprazole 65.65 ng mL^?1, esomeprazole 131.27 ng mL^?1, domperidone 98.33 ng mL^?1 and itopride 162.35 ng mL^?1. The study showed that reversed-phase liquid chromatography is sensitive and selective for the determination of pantoprazole, rabeprazole, esomeprazole, domperidone and itopride using single mobile phase.     

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.     

Simultaneous preconcentration and determination of malachite green and fuchsine dyes in seafood and environmental water samples using nano-alumina-based molecular imprinted polymer solid-phase extraction

Molecular imprinted polymer for determination of malachite green (MG) and fuchsine basic (FU) dyes by spectrophotometry has been used, to develop a novel simultaneous extraction and preconcentration method. Molecularly imprinted layer-coated nano-alumina (MIP@Nano-Al₂O₃) as adsorbent was prepared by surface molecular imprinting technique, and characterised by FTIR spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis (EDAX) and thermogravimetric analysis (TGA). The method is based on simultaneous extraction of MG and FU dyes from aqueous solution by using molecularly imprinted polymer and measuring the absorbance at 617 and 546 nm for MG and FU, respectively. Parameters which affect the extraction efficiency such as pH, volume of eluent and amount of adsorbent were investigated and optimised. Linear calibration curves were obtained in the range of 2–750 ng mL^?1 for MG and 1–240 ng mL^?1 for FU under optimum conditions. Detection limit based on three times the standard deviation of the blank (3S_b) was 0.655 and 0.245 ng mL^?1 (n = 10) for MG and FU, respectively. The relative standard deviation (RSD) for 100 ng mL^?1 of MG and FU was 2.35 and 3.06% (n = 7), respectively. The method was applied to the simultaneous determination of the dyes in different seafood and environmental water samples.     

Determination of Danofloxacin and Marbofloxacin in Milk Samples by Micellar Liquid Chromatography with Fluorescence Detection

Abstract

A simple, rapid, and sensitive analytical method has been developed for the determination of two fluoroquinolones, danofloxacin and marbofloxacin, in bovine milk samples. Separation and quantification were performed by micellar liquid chromatography with fluorescence detection (MLC?FD), using sodium dodecyl sulfate (SDS) as a surfactant. The influence of the principal factors, namely, the micelle concentration, the amount of organic modifier, tail‐reducing agents, the pH, and the temperature were studied. The suitable condition was found to be 75 mM SDS?10 mM phosphate buffer–18 mM tetrabutylammonium bromide/3% (v/v) 1‐propanol at pH 3.0 for the separation of marbofloxacin, danofloxacin, and tosufloxacin (internal standard) in about 20 min. The linear concentration range of application was 1.8–30.0 ng · mL^?1 for danofloxacin and 16–120 ng · mL^?1 for marbofloxacin, and the relative standard deviation ranged between 4.9 and 2.7%. The limit of detection found for danofloxacin was 0.5 ng · mL^?1 and 5 ng · mL^?1 for marbofloxacin. These values were lower than the maximum residue limits (MRLs) established by the European Union for these compounds in bovine milk. It was applied to check the eventual existence of these compounds above these limits on commercial milk samples. The validation method was completed with spiked milk samples. Recovery levels obtained were 90.3–108.2%.     

Custom-Made C18 Column for Simultaneous Determination of Endocrine Disrupting Substances in Water by Diode-Array and Fluorescence Detectors

A C₁₈ stationary phase was synthesized for a custom-made HPLC column. When compared to a commercial C₁₈ column, better chromatographic performances were obtained. This column was successfully applied for simultaneous determination of p,p′-DDT, o,p′-DDT, benzo(a)anthracene, benzo(b)fluoranthene, and benzo(a)pyrene in waters by high performance liquid chromatography coupled with dual detectors (diode array and fluorescence detectors) combined with solid phase extraction. Low method detection limits were obtained, i.e., p,p′-DDT: 0.5 µg L^?1, o,p′-DDT: 1 µg L^?1, benzo(a)anthracene: 2.5 ng L^?1, benzo(b)fluoranthene: 5 ng L^?1, and benzo(a)pyrene: 2.5 ng L^?1. High recoveries that ranged from 82 to 94% were obtained for all compounds.     

Simultaneous Determination of Gallium(III) and Indium(III) in Urine and Water Samples with Cloud Point Extraction and by Inductively Coupled Plasma Optical Emission Spectrometry

A simple, sensitive, and selective method for the determination of gallium and indium in different samples at trace levels is presented. This method was based on complexation of analyzes with 2-(5-bromo-2- pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in the presence of t-octylphenoxy-polyethoxyethanol (Triton X-100). After phase separation, the analyzed concentrations were determined by inductively coupled plasma optical emission spectrometry. Quantitative extraction of gallium and indium was performed at pH 7.0, 1.7 mmol L^?1, 5-Br-PADAP, 1.3% (w/v) Triton X-100 and at 75°C. The relative standard deviations (RSD) of this method were between 0.3% and 1.6% (C = 20 ng mL^?1, n = 9). The calibration curve is linear over the concentration range 6–200 ng mL^?1 for gallium and 2–200 ng mL^?1 for indium, respectively. The limits of detection (LOD) for gallium and indium were 0.72 and 0.28 ng mL^?1, respectively. The results showed the developed method was not susceptible to matrix effects, providing recoveries between 98% and 102%. The accuracy of the developed method was evaluated by the analysis of spiked certified reference materials. The developed method was successfully applied to gallium and indium determination in urine and lake water with satisfactory results.