Colorimetric Determination of Propofol in Bulk form,Dosage Form and Biological Fluids

ABSTRACT

Propofol is coupled with 2, 6-dichloroquinone-4-chlorimide (DCQ) in a reaction buffered at pH 9.6 to give a colored product having an analytically useful maximum at 635 nm. The factors affecting the color generation were optimized and incorporated in the procedure. The reacted propofol has a molar absorptivity of 3.9 × 10^?4 L mol^?1 cm^?1, and Beer's law is obeyed for concentrations 1-5 μg ml^?1 with detection limit 0.25 μg ml^?1. The method was found applicable to biological fluids (plasma and urine) spiked with propofol at concentration levels 1-5 μg ml^?1 for plasma and 1-5 μg 0.5 ml^?1 urine (less sensitivity is obtained with urine volumes above 0.5 ml) with detection limits 0.28 μg ml^?1 for plasma and 0.4 μg 0.5 ml^?1 urine. The average recovery for the commercial preparation (1% w/v propofol emulsion intravenous injection for infusion) was 99.54% with an RSD of 1.05%. The method was validated by an adopted HPLC method. The results obtained by the HPLC method for the commercial preparation were statistically compared with the proposed method and evaluated at the 95% confidence limits.     

Electrosorption of vitamin K1 at mercury and its determination at submicrogram levels by differential pulse voltammetry at a hanging mercury electrode

The electrochemical behaviour of vitamin K₁ has been studied in ethanolic and methanolic acetate buffers by cyclic voltammetry and differential pulse voltammetry (d.p.v.) at the h.m.d.e. and differential pulse polarography at the d.m.e. Increased adsorption occurs at the mercury electrode as the percentage of water is increased. The most sensitive signal was obtained by d.p.v. with acetate-buffered 60% methanolic solutions; vitamin K₁ could then be measured down to 10 ng ml^-1.     

Selective chemiluminescence method for monitoring of vitamin K homologues in rheumatoid arthritis patients

Vitamin K is a fat-soluble vitamin involved in blood coagulation and bone metabolism. The detection and monitoring of vitamin K homologues in rheumatoid arthritis (RA) patients is a challenging problem due to the smaller concentrations of vitamin K and the presence of several interfering medications. Therefore, this study aimed to develop a new highly sensitive and selective chemiluminescence (CL) method designated to quantify vitamin K homologues in plasma of RA patients including phylloquinone (PK, vitamin K₁), menaquinone-4 (MK-4, vitamin K₂) and menaquinone-7 (MK-7, vitamin K₂). The method was based on the unique photochemical properties of vitamin K homologues that were exploited for selective luminol CL reaction. The correlation coefficients of 0.998 or more were obtained in the concentration ranges of 0.1-100 ng mL⁻¹ vitamin K homologues. The detection limits were 0.03-0.1 ng mL⁻¹ in human plasma for vitamin K homologues. The developed HPLC-CL system was successfully applied for selective determination of vitamin K homologues in plasma of RA patients. The developed method may provide a useful tool for monitoring vitamin K homologues in different clinical studies such as RA, osteoporosis and hepatocellular carcinoma in which vitamin K is intervented.     

On-line preconcentration and determination of cobalt by chelating microcolumns and flow injection atomic spectrometry

A simple and sensitive flow injection analysis-atomic absorption spectrometric procedure is described for the determination of cobalt. The method is based upon on-line preconcentration of cobalt on a microcolumn of 2-nitroso-1-naphthol immobilized on surfactant coated alumina. The trapped cobalt is then eluted with ethanol (250 μl) and determined by flame atomic absorption spectrometry. The analytical figures of merit for the determination of cobalt are as follows: detection limit (3 S), 0.02 ng ml⁻¹; precision (RSD), 2.8% for 20 ng ml⁻¹ and 1.7% for 70 ng ml⁻¹ of cobalt; enrichment factor, 125 (using 25 ml of sample). The method has been applied to the determination of cobalt in water samples, vitamin B₁₂ and B-complex ampoules and accuracy was assessed through recovery experiment and independent analysis by furnace AAS.     

Recombination System Based on Cre α Complementation and Leucine Zipper Fusions

A gene encoding β-1,3-1,4-glucanase was cloned by polymerase chain reaction (PCR) from Bacillus subtilis MA139. Sequencing result showed 97% homology to the corresponding gene from Bacillus licheniformis. The open reading frame (ORF) of the gene contained 690 bp coding for a 226 amino-acid matured protein with the estimated molecular weight of 24.44 kDa. The β-1,3-1,4-glucanase gene was subcloned into an expression vector of pET28a and expressed in Escherichia coli BL21 and then purified by metal affinity chromatography using a nickel–nitrilotriacetic acid (Ni–NTA) column. The purified β-1,3-1,4-glucanase demonstrated 24.05 and 12.52 U ml^-1 activities for the substrates of barley β-glucan and lichenan, respectively, and the specific activities were 728.79 and 379.1 U mg^-1 for them, respectively. The optimal temperature and pH of the purified enzyme were 40°C and 6.4, respectively. When barley β-glucan was used as the substrate, K _m was 5.34 mg ml^-1, and K _cat showed 7,206.71 S^-1, thus the ratio of K _cat and K _m was 1,349.67 ml s^-1 mg^-1. The activity of β-1,3-1,4-glucanase was affected by a range of metal ions or ethylenediaminetetraacetic acid (EDTA).     

The synthesis and analytical capabilities of chromogenic aza-12-crown-4 as a selective reagent for lithium ion

The synthesis and analytical capabilities of a new chromogenic crown ether, 1-(2-hydroxy-5-nitrobenzyl)-1-aza-4,7,10-trioxacyclododecane, chromogenic aza-12-crown-4. Constants found for this aza-12-crown-4 were pK_a1 = 5.77, pK_a2 = 10.31, pK_ex (Li) = 10.18, and pK_ex (Na) = 12.50. The calibration curve obtained for the extraction-spectrophotometric procedure was linear from 0.3 to 2 μg ml^?1. The imprecision of the measurement was calculated from the mean value of the standard deviations of triplicate samples over the linear range and was less than 5%. Results for the determination of lithium in blood serum and urine exhibited good agreement with atomic absorption data.     

Reverse-FIA with spectrophotometric detection method for determination of vitamin C

Simple reverse flow injection analysis (rFIA) manifold with spectrophotometric detection was developed for an indirect determination of ascorbic acid. Parameters such as stability, accuracy and precision were established for the method and evaluated statistically to assess the applications of the method. Ascorbic acid in this procedure accelerates dediazoniation reaction of formed diazonium ions; hence its quantity can be determined by monitoring the derivatization product from coupling unreacted diazonium ion with phenol to give an azo dye (coupling reaction). The rFIA design was based on the injection of sodium nitrite into an acidic p-aminoacetophenon carrier stream in which diazonium ion was formed. This ion was inhibited by ascorbic acid stream before coupling with the phenol-Na₂CO₃ stream. Under optimum conditions, ascorbic acid acts in accordance with the Beer??s law at two concentration ranges 0.4?C6.5 ??g ml^?1 (R = 0.9995) and 7.0?C20.0 ??g ml^?1 (R = 0.9949), with detection limits of 0.25 ??g ml^?1. The developed method was applied to the determination of vitamin C in pharmaceutical formulations which produced satisfactory results compared with the standard methods reported in the British Pharmacopoeia.     

LC-UV Column-Switching for Quantitation of Vitamin K1 in Infant Formula

This study was undertaken in order to develop an analytical method for vitamin K₁ in infant formula. The content of vitamin K₁ was investigated by using a column-switching LC-UV method. A Certified Reference Material sample of infant formula containing 0.94 ± 0.04 mg kg^?1 of vitamin K₁ was extracted with hexane followed by enzymatic digestion of fat and precipitation of the fatty acids. The linearity of this method was calculated using five consecutive standard curves, and the coefficient of determination (r ²) was found to be 0.9995. The limit of detection (LOD) and the limit of quantitation (LOQ) was 3.31 and 11.12 μg L^?1, respectively. The accuracy of intra- and inter-day measurements was in the range from 96.67 to 108.67%, and the precision of intra- and inter-day measurements was less than 5.13%. The recoveries were 109.27 ± 5.92%, and the recoveries of inter-laboratory results were in the range from 97.59 ± 1.29 to 109.27 ± 5.92%. The newly developed method uses the optimum conditions required to determine the content of vitamin K₁ in infant formula.     

Flow-injection spectrophotometric determination of ascorbic acid by reduction of vanadotungstophosphoric acid

Ascorbic acid may be determined spectrophotometrically at 360 nm based on reduction of vanadotungstophosphoric acid using flow-injection analysis. The carrier stream was distilled water and the reagent streams were buffer solution (pH 3.0), 1.735 × 10^?3 M dodecatungstophosphoric acid and 1.735 × 10^?3 M sodium vanadate. The injection rate was 80 h^?1. The calibration graph was linear up to 80 μg ml^?1 ascorbic acid and the relative standard deviation for the determination of 20 μg ml^?1 ascorbic acid was 1.5% (n=10). The detection limit was 1.0 μg ml^?1 ascorbic acid, based on an injection volume of 250 μl. The system was applied to the determination of ascorbic acid in vitamin C tablets.     

Simultaneous determination of cobalt and chromium by ion chromatography with chemiluminescence detection and its application to glass analysis

A method is described for the simultaneous determination of very low levels of Co and Cr by high performance ion chromatography coupled with a chemiluminescence detection system. 0.1M K₂SO₄ solutions, adjusted to pH 3.0, were used as eluent to separate Co(II) and Cr(III) between them and from interferents. The detection system was the chemiluminescence of luminol/ H₂O₂ in alkaline medium catalyzed by such transition metals. Using a matrix solution analogous to soda-lime silica glass (dissolved in acids) calibration graphs were linear up to 0.5 ng ml^–1 for cobalt and up to 250 ng ml^–1 for chromium. The corresponding calculated detection limits (3 s) in such matrix were 0.05 ng ml^–1 and 15 ng ml^–1 for Co and Cr, respectively. The relative standard deviations were 1.4% at 0.5 ng ml^–1 Co level and 2.8% at the 200 ng ml^–1 Cr level. No interferences were observed from the more common metals, particularly those present in glass samples. The ion chromatography/ chemiluminescent method proposed has been successfully applied to the analysis of Co and Cr in glasses.     

Determination of clarithromycin in rat plasma by HPLC-UV method with pre-column derivatization

A novel high-performance liquid chromatographic (HPLC) method using pre-column derivatization and UV detection at 275 nm for the determination of clarithromycin in rat plasma has been validated. Clarithromycin was extracted from plasma sample spiked with internal standard (erythromycin) under alkaline condition with ethyl ether and derivatizated with trimethylbromosilane. The analyses were run on a C₁₈ column, maintained at 40 °C during elution, using a mobile phase comprised of potassium dihydrogen phosphate (50 mM, pH 6.8, contained 0.7% triethylamine), acetonitrile, and methanol (30:45:25, v/v/v). The standard calibration curve for clarithromycin was linear (r² = 0.9998) over the concentration range of 0.1-10 μg ml⁻¹ in rat plasma. The limit of detection (LOD) and limit of quantitation (LOQ) was 30 ng ml⁻¹ and 0.1 μg ml⁻¹ respectively. The intra- and inter-day assay variability range was 2.6-7.4% and 3.3-8.5%, respectively. This method has been successfully applied to a pharmacokinetic study of clarithromycin in rats.     

Determination of ultra-trace levels of cobalt by ion chromatographic separation and chemiluminescence detection

A luminol chemiluminescence detection/flow injection analysis technique coupled with ion chromatography (IC) has been examined for the selective determination of cobalt (II) at pg ml^?1 levels. A barium chloride solution was used as an eluent in the IC to separate cobalt(II) from interferents. When a 100-μ1 sample injection volume was used, the detection limit was 1.0 pg ml^?1 cobalt; the minimum detectable amount of cobalt was 100 fg. The calibration graph was linear above 10 pg ml^?1 and the linear dynamic range extended over six orders of magnitude. The relative standard deviation for ten replicate measurements of 30 pg ml^?1 cobalt was 3.8%. The results of the analysis of a synthetic sample corresponding to a boiling-water reactor coolant and some commercially available copper(II) standard solutions are given.     

Polarography of disodium pentacyanonitrosylferrate(II): Part 2. Determination at Therapeutic Levels in Serum,Plasma, and Whole Blood

Disodium pentacyanonitrosylferrat(II) (sodium nitroprusside) is determined at therapeutic (ng ml^?1) levels in plasma, serum and blood with conventional and high-performance differential pulse polarography (d.p.p. and h.p.d.p.p.) at a dropping mercury electrode or a static mercury drop electrode. Serum or plasma (3 ml) is treated with perchloric acid containing 1 mg ml^?1 potassium hexacyanoferrate(II), centrifuged for 10 min and subjected to polarography. For spiked serum, calibration graphs are linear over the range 30–1000 ng ml^?1 sodium nitroprusside, regardless of the polarographic technique; the estimated detection limit is 15 ng ml^?1 (5 × 10^?8 M). Calculated therapeutic levels range from 100 to 1000 ng ml^?1. Similar results were obtained for spiked plasma. A similar procedure is suitable for whole blood and was used to study the in-vitro degradation of sodium nitroprusside (200 ng ml^?1) on incubation at 37°C. The in-vitro loss is rapid (t_{$\text{1}\text{2}$} ≈ 6 min) but meaningful in-vivo levels can be obtained when the blood is collected in a 0.9% sodium chloride solution at 0°C. Thiocyanate, the main metabolite of nitroprusside, and thiosulphate, which is a potential antidote for cyanide, do not interfere.     

Sorption of arsenic,antimony and bismuth on glycolmethacrylate gels with bound thiol groups for direct sampling in electrothermal atomic absorption spectrometry

Batch sorption of arsenic, antimony and bismuth from solutions in 1 M sulphuric acid has distribution coefficients of 10⁴–10⁵. Quantitative sorption on the hydrophilic methacrylate gel containing thiol groups (Spheron Thiol) is possible within 60 min for bismuth or arsenic and 120 min for antimony. Conditions for the electrothermal atomization of arsenic sorbed on Spheron Thiol and injected into the graphite tube as a suspension are optimized. The sensitivities possible are 3.2 ng As ml^-1, 13 ng Sb ml^-1 and 2.8 ng Bi ml^-1; the coefficient of variation for 10 ng of As is 4%. Complete recovery of 40 ng As ml^-1 added to solutions of 5% KCI or 5% MgCl₂ and to river water was obtained.     

A rapid determination of propiverine and its N-oxide metabolite in human plasma by high performance liquid chromatography-electrospray ionization tandem mass spectrometry

A simple, fast and sensitive high-performance liquid chromatography (HPLC)-electrospray ionization (ESI) tandem mass spectrometric method (LC-MS/MS) has been developed for determination of propiverine and propiverine N-oxide metabolite in human plasma using oxybutynin as internal standard. Instead of extracting propiverine from plasma using organic solvents, which should be separated from the aqueous phase and evaporated before injecting the sample into the chromatograph, plasma sample containing propiverine and N-oxide was directly injected after precipitating proteins with acetonitrile. Numerous compounds in the plasma did not interfere with the highly specific multiple reaction monitoring in tandem mass spectrometric detection following C₈ reversed-phase chromatographic separation under conditions that eluted propiverine, N-oxide and oxybutynin within 2 min (0.1% formic acid in water/acetonitrile, 25:75, v/v). The LC-MS/MS method and an alternative LC-MS method, using methyl-t-butyl ether extraction and selected ion monitoring, were validated over 1-250 ng ml⁻¹ of propiverine and 2 to 500 ng ml⁻¹ of N-oxide, and successfully applied in a pharmacokinetic study. The lower limit of quantitation was 1 ng ml⁻¹ for propiverine and 2 ng ml⁻¹ for N-oxide in both methods.     

Effect of matrix modifier and furnace material on the determination of traces of fluoride by electrothermal molecular absorption spectrometry of aluminum monofluoride

In the determination of fluoride by AlF absorbance measurements, the interference from strontium nitrate is avoided by using magnesium nitrate or barium nitrate added to aluminum solution as the matrix modifier. The effects of the graphite-furnace material on AlF absorbance are investigated. Glassy carbon and synthetic carbon gave longer furnace lifetimes and better sensitivity than the other materials tested. The maximum sensitivity (4.2 μg ml^?1 fluoride for 0.0044 absorbance with a 10-μl injection) was obtained with synthetic carbon. The r.s.d, was <5% for 0.1 μg ml^?1 fluoride (n=10). Na⁺, K⁺, Pb²⁺, Zn²⁺, Cu²⁺ and Ag⁺ did not affect the measurements up to 500 μg ml^?1, but Ni²⁺, Co²⁺, Fe²⁺, Sr²⁺ and especially Ca²⁺ depressed the absorbance.     

THE USE OF CARBOXYMETHYL ETHOXYLATE SURFACTANT TO DISSOLVE VITAMIN K1 AND TO OBTAIN LOW INTERFACIAL TENSION AND STABLE EMULSION SYSTEMS

Abstract

The presence of vitamin K₁ in human body is important for preventing the hemorrhagic disease. Due to its very long side chain, vitamin K₁ is highly insoluble in water. We have successfully dissolve a substantial amount of vitamin K₁ in solutions of a commercial surfactant containing carboxymethyl ethoxylates (Hüls B433) and obtained low interfacial tension (IFT) and stable emulsion systems. This paper will present the details of these experiments. The solubilization of vitamin K₁ was estimated from UV absorption. The IFT values were measured by using a spinning drop apparatus and all particle sizes were determined by using laser light scattering. By using the Hüls B433 surfactant and an optimum amount of CaCl₂, we can dissolve vitamin K₁ in water and obtain low IFT systems in the order of 10^?2 dyne/cm. The emulsions obtained in these systems are stable and contain droplet sizes below 65 nm. The dissolution of vitamin K₁ and the IFT behavior in these systems follow the rules for crude oil and prefer larger surfactant micelles.     

Evaluation of continuous hydride generation combined with helium and argon microwave induced plasmas using a surfatron for atomic emission spectrometric determination of arsenic,antimony and selenium

The direct coupling of continuous hydride generation with both Ar and He microwave induced plasmas (MIP) sustained in a surfatron has been optimized for the simultaneous determination of arsenic, antimony and selenium with atomic emission spectrometry. While a discharge tube of quartz was found suitable for the Ar plasma, the use of an Al₂O₃ tube led to improved performance of the He plasma. The He MIP was found to be less tolerant to the introduction of hydrogen than the Ar MIP, and correspondingly the hydride generation should be operated at a lower flow rate of 0.5% NaBH₄ solution. The introduction of the H₂O vapour produced during hydride generation into both discharges was found to greatly decrease the sensitivities and to degrade the measurement precision. It could be effectively removed with trapping by concentrated H₂SO₄. The detection limits (3σ) for As, Sb and Se are 1, 0.4 and 1 ng ml⁻¹ with the Ar MIP, and 2, 0.3 and 6 ng ml⁻¹ with the He MIP, respectively. The calibration curves are linear over three decades of concentration. The mutual interferences from As(III), Sb(III), Se(IV), Bi(III) and Sn(IV) were found to be negligible at interferent concentrations below 1 μg ml⁻¹ and in most cases the tolerable interferent concentrations are up to 20 μg ml⁻¹. The proposed method has been applied to the determination of As, Sb and Se in tea samples at μg g⁻¹ levels.     

Synthesis and characterization of carboxymethyl cellulose-silver nanoparticle (AgNp)-silica hybrid for amylase immobilization

Carboxymethyl cellulose-silver nanoparticle (AgNp)-silica hybrids have been synthesized in a modified Stöber process. The hybrid synthesis was optimized to obtain an efficient immobilization matrix for diastase alpha amylase, a multimeric enzyme of high technological significance. The synthesized hybrids were characterized using FTIR, XRD, SEM, TGA and BET studies. The enzyme immobilization was done by adsorption and using the immobilized enzyme, the hydrolysis of soluble starch has been optimized in comparison to free enzyme. The optimum usable pH for the immobilized enzyme ranged from pH 4 to 5, while pH 5 was optimum pH for the free enzyme activity. The kinetic parameters for the immobilized, (K _M = 3.4610 mg ml^?1; V _max = 6.3540 mg ml^?1 min^?1) and free enzyme (K _M = 4.1664 mg ml^?1; V _max = 4.291 mg ml^?1 min^?1) hydrolysis indicated that the immobilization at the nanohybrid has significantly improved the catalytic property of the enzyme. In the immobilized state, the enzyme remained usable for many repeated cycles like our previous material, gum acacia-gelatin-AgNp-silica. Storage experiments indicated that the immobilization has increased the stability of the enzyme and also that AgNps play a role in stabilizing the immobilized enzyme.     

Flow injection chemiluminescence determination of carbaryl using photolytic decomposition and photogenerated tris (2,2′-bipyridyl)ruthenium(III)

A flow injection (FI) system combined with two photochemical processes is developed for the sensitive and rapid determination of carbaryl. It is based on the on-line photo-conversion of carbaryl into methylamine which subsequently reacts with Ru(bpy)₃³⁺ generated through the on-line photo-oxidation of Ru(bpy)₃²⁺ with peroxydisulphate. The linear concentration range of application was 0.04-4.0 μg ml⁻¹ of carbaryl, with an R.S.D. of 1.2% (for a level of 0.50 μg ml⁻¹) and a detection limit of 0.012 μg ml⁻¹. The sample throughput was 200 injections per hour. The applicability of the method was demonstrated by determining carbaryl in commercial formulations, water, soil, grain and blood serum.