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.     

Determination of acid volatile sulphur in river sediments by ICP-OES coupled with purge and trap method

The developed and tested method is based on the acid volatile sulphur (AVS) releasing from a sample of sediment by acidification with hydrochloric acid and sequential absorption of released hydrogen sulphide into the absorption solution of sodium hydroxide. Total sulphur absorbed in the absorption solution is subsequently determined by inductively coupled plasma optical emission spectrometry (ICP-OES) technique. The method was tested using both model and real samples of the river sediment. Obtained results were compared with the results of iodometric determination as the method routinely used for the AVS determination. In case of using ICP-OES with purge and trap, there is no spectral interference of calcium; therefore for the determination of sulphur, it is possible to use atomic emission line of sulphur S I 180.7 nm. The tested method provides the results comparable with the iodometric method within the range of tested concentrations. The detection limit (LOD) of this method is 0.09 mg· S^2? ? L^?1 in the absorption solution which corresponds to 0.23 mg S^2?·kg^?1 in a sediment. Value of LOD is comparable with the iodometric determination.     

New Spectrophotometric Method for the Determination of Titanium in Soil and Standard Geochemical Samples

Abstract

In the present communication a simple and rapid spectrophotometric method for the determination of titanium is described. The method is based on the reaction of Ti(IV) with a newly synthesized reagent, 6-(4-nitrophenylazo)-3,4,5-trihydroxy benzoic acid (NATHB), in ethanol medium at pH 3.2 to 4.2. The complex exhibits an absorption maximum at 495 nm and Beer's law is valid over the range of 0.04 – 1.00 μg.ml^?1 Ti. The molar absorptivity is 3.48 × 10⁴ dm³.mole^?1. cm^?1. Most of the foreign metal ions and anions do not produce any colorations with NATHB at selected conditions. Based on these results, a simple and direct spectrophotometric method with high selectivity and sensitivity was proposed. The method has been successfully applied for the determination of titanium in 5 soil and 3 standard geochemical samples.     

A modified radiometric method for plutonium determination in irradiated fuel

A modified radiometric method for the determination of plutonium in irradiated nuclear fuel is described. The analysis consists of total plutonium alpha-activity, activity ratio²³⁸Pu:(²³⁹Pu+²⁴⁰Pu) and burnup determination. The error of plutonium determination is practically identical with that of a classical radiometric method. The method suggested is suitable for large sample series of the same type of irradiated nuclear fuel.     

A rapid method for determining strontium-90 in urine samples

Rapid bioassay methods for ⁹⁰Sr in urine samples are needed to provide an early estimation of possible internal dose resulting from exposure to radiostrontium in the event of a radiological and nuclear emergency. In this work, a fast column separation method followed by liquid scintillation counting for detection of ⁹⁰Sr in urine was developed. Replicate spike and blank samples were analyzed for performance evaluation of the method. Using this method, a detection limit of ~10 Bq L^?1 for ⁹⁰Sr can be achieved with a sample analysis turn-around time of 4 h for a set of 12 samples. The method is adequate to meet the radiobioassay acceptance criteria and is suitable for quick dose assessment of ⁹⁰Sr exposure following a radiation emergency.     

Determination of ethamsylate in pharmaceutical preparations by irreversible biamperometry

A novel flow-injection irreversible biamperometric method is described for the determination of ethamsylate. The proposed method is based on the oxidation of ethamsylate at one platinum electrode and the reduction of permanganate at another to form an irreversible biamperometric detection system. Ethamsylate can be determined over the range 1.0×10⁻⁶-1.0×10⁻⁴ mol l⁻¹ with a sample measurement frequency of 180 samples h⁻¹. The detection limit for ethamsylate is 4.0×10⁻⁷ mol l⁻¹. The stability of the proposed method is shown by a RSD of 0.52% for 11 replicate determinations of 2.0×10⁻⁵ mol l⁻¹ ethamsylate. The proposed method was applied to the determination of ethamsylate in pharmaceutical preparations.     

Determination of131I in soil using a liquid anion exchanger and liquid scintillation technique

A simple method for rapid determination of¹³¹I in soil is described. The method is based on the specific separation and concentration of radioiodine from the soil extract with a liquid anion exchanger and measuring its radioactivity with liquid scintillation counting. The¹³¹I from soil is extracted with aqueous solution of sodium hydroxide. The method permits the determination of¹³¹I with a lower limit of detection less than 0.1 Bq/10 g of soil.     

New Spectrophotometric Method for Sulfite Determination

Abstract

A highly selective spectrophotometric method for the determination of aqueous sulfite was developed. Sulfite was found to react with o-phthaldialdehyde in presence of ammonia yielding a deep blue colored complex the absorbance of which is sensitive to trace sulfite concentrations. The method is simple, very sensitive, and convenient for the determination of as little as 5X10^?6 M sulfite. The molar absorptivity of the colored complex is about 1.2X10⁴ L cm^?1 mol^?1. The proposed method is more sensitive and selective for sulfite than the widely used Ellman reagent method. Absorbance is measured at 628 nm which is the best of the two absorption maxima that are exhibited by the compound.     

Rapid determination of actinides in urine by inductively coupled plasma mass spectrometry and alpha spectrometry: A hybrid approach

A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are split between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3 h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6 h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically greater than 90%, in contrast to other reported methods using flow injection separation techniques for urine samples where plutonium yields were 70-80%. This method allows measurement of both long-lived and short-lived actinide isotopes. ²³⁹Pu, ²⁴²Pu, ²³⁷Np, ²⁴³Am, ²³⁴U, ²³⁵U and ²³⁸U were measured by ICP-MS, while ²³⁶Pu, ²³⁸Pu, ²³⁹Pu, ²⁴¹Am, ²⁴³Am and ²⁴⁴Cm were measured by alpha spectrometry. The method can also be adapted so that the separation of uranium isotopes for assay is not required, if uranium assay by direct dilution of the urine sample is preferred instead. Multiple vacuum box locations may be set-up to supply several ICP-MS units with purified sample fractions such that a high sample throughput may be achieved, while still allowing for rapid measurement of short-lived actinides by alpha spectrometry.     

Isotope analysis of strontium by multicollector inductively-coupled plasma mass spectrometry: High-precision combined measurement of 88Sr/86Sr and 87Sr/86Sr isotope ratios

The paper describes a new high-precision method for the simultaneous precise determination of ⁸⁸Sr/⁸⁶Sr and ⁸⁷Sr/⁸⁶Sr ratios in a single portion of a geological sample by multicollector inductively coupled mass spectrometry (MC-ICP-MS). The isotope analysis is carried out with mass bias effect correction by a combination of internal normalization to the standard Zr-isotope ratio and bracketing standard method (external normalization). Our results for geochemical IAPSO and BCR-1 standard samples are in a good agreement with the published data. The reproducibility of the ⁸⁸Sr/⁸⁶Sr ratio varies from ±0.015 to ±0.05?? (depending on the sample features) and, together with the analysis accuracy, is superior to the previously reported methods of MC-ICP-MS analysis. Still ahead is only double spike thermal ionization mass spectrometry with its ±0.02?? reproducibility. However, the new method allows the simultaneous determination of ⁸⁸Sr/⁸⁶Sr and ⁸⁷Sr/⁸⁶Sr ratios and its productivity is higher by 5 to 6 times. On the other hand, in sample preparation, it is necessary to strive for at least 95% Sr yield from the chromatographic column; otherwise the sorption-desorption process may lead to a 0.6?? ⁸⁸Sr/⁸⁶Sr ratio bias relative to the true value.     

Comparison of test methods for oxygen permeability: Optical method versus carrier gas method

The oxygen permeability of films is relevant for packaging related and technical applications. An increasingly used test method for the measurement of oxygen permeability is the optical test method, because it allows a simple and cost-efficient measurement setup. This method is based on optical chemical sensors. However, not much is known about its validity. Therefore, method validation is necessary which is subject of this study. The optical method is compared with the carrier gas method for a variety of film samples. In the tested permeability range of 0.5–2500 cm³ (STP)·(m² d bar)⁻¹ both methods deviated less than 20% for zero and 50% relative humidity.     

Voltammetric determination of morphine on stationary platinum and graphite electrodes

A voltammetric method for the determination of morphine in poppy seeds, crude morphine and pharmaceutical preparations is described. The method is based on electrochemical oxidation of morphine at a stationary graphite or platinum electrode in basic electrolyte. The mechanism of the electrochemical oxidation of morphine and its derivatives are discussed. The proposed method shows good reproducibility, and sample preparation is simple. The working ranges are 6 × 10^-5–10^-3 M with the graphite electrode and 10^-5–10^-3 M with the platinum electrode. There is no interference from various morphine derivatives or minor alkaloids at the 10^-3 M level.     

Determination of Aluminum in Drinking Waters by A.C. Oscillopolarography in a Lithium Chloride System

Abstract

A new and convenient method for the rapid determination of aluminum in drinking waters using a.c. oscillopolarography in a lithium chloride system is described in this paper. The calibration graph is linear from 5 × 10^?6 to 8 × 10^?5 mol/L with a detection limit of 5 × 10^?6 mol/L. The relative standard deviation of the method is 4.7% for 4 × 10^?5 mol/L Al. Compared with other techniques, this method has the significant advantages of simple instrumentation, no deaeration procedure required and rapid measurement. It was particularly suitable to the analysis of 10^?6 ~ 10^?5 mol/L levels of Al in drinking waters.     

Simple UV and visible spectrophotometric methods for the determination of doxycycline hyclate in pharmaceuticals

Doxycycline hyclate (DOX), a broad spectrum antibiotic with activity against a wide range of gram-positive and gram-negative bacteria, is widely used as a pharmacological agent and as an effector molecule in inducible gene expression system. Three simple, selective, rapid, accurate, precise and cost-effective spectrophotometric methods for the determination of DOX in bulk drug and in tablets have been developed and validated. First method (method A) is based on the measurement of absorbance of DOX in 0.1 M HCl at 240 nm. The second method (method B) is based on the measurement of yellow chromogen at 375 nm which is formed in 0.1 M NaOH. The third method is based on the measurement of 2: 1 complex formed between DOX and iron(III) in H₂SO₄ medium, the complex peaking at 420 nm (method C). The optimum conditions for all the three methods are optimized. Beer’s law was obeyed over the ranges 2.5–50.0, 1.50–30.0 and 10–100 g/mL for method A, method B and method C, respectively. The apparent molar absorptivity values are calculated to be 1.03 × 10⁴, 1.73 × 10⁴, and 5.21 × 10³ L mol⁻¹ cm⁻¹ for method A, method B, and method C, respectively. The Sandell sensitivity, limit of detection (LOD) and limit quantification (LOQ) values are also reported. All the methods were validated in accordance with current ICH guidelines. The developed methods were employed with high degree of precision and accuracy for the estimation of total drug content in commercial tablet formulations of DOX.     

Trace determination of gaseous chlorine: a comparison between an electrometric method and the methyl orange photometric method

Two methods for the determination of molecular chlorine in air are critically compared. An electrometric method based on measurement of the reduction current of chlorine to chloride is superior to the photometric determination based on bleaching of an acidic solution of methyl orange. The limit of detection for the electrometric method is 50 μg m^-3; the standard error of the mean is better than 2%, and the sensitivity is 5.9 μg m^-3 μ A^-1 at +50 mV applied potential versus SCE with a mercury cathode. The limit of detection for the photometric method is 300 μg m^-3; the precision is of the order of 5%, and the sensitivity is 80 μg m^-3 for an error of 1% in the absorption measurements. The accuracy of the electrometric method is good whereas the photometric method yields consistently low results. The electrometric method is less subject to interferences than the photometric method.     

Spectrophotometric determination of lithium ion with the chromogenic crown ether, 2″,4″-dinitro-6″-trifluoromethylphenyl-4′-aminobenzo-14-crown-4

A spectrophotometric method of determining alkali metal ions with a chromogenice crown ether reagent was found to be more selective and sensitive than an ion-pairing method based on the same size of crown ether cavity. It is shown that in the ion-pairing method, the sensitivity toward lithium ion was 5.685 × 10^?4 absorbance/mg l^?1, with sodium interfering at 300 mg l^?1. The chromogenic crown ether, 2″,4″-dinitro-6″-trifluoromeethylphenyl-4′-aminobenzo-14-crown-4, was much superior to benzo-14-crown-4. The sensitivity of the chromogenic crown ether was 1.69 × 10^?3 absorbance/mg l^?1. This represents a three-fold increase in sensitivity and less reagent is needed (2 × 10^?4 M for the chromogenic method versus 1.4 × 10^?3 M for ion-pairing). Interference from sodium decreased to 3000 mg l^?1. The reagent was used to determine lithium ion in treated blood serum samples in both a batch and flow injection method and results were compared with data obtained with atomic absorption; excellent agreement was obtained in all cases.     

Spectrophotometric determination of nitrite in polluted waters using 3-nitroaniline

Nitrite reacts with 3-nitroaniline in the presence of hydrochloric acid to form a diazonium cation, which is subsequently coupled with N-(1-naphtyl)ethylenediammonium chloride to form a stable purple azo dye. The method is suitable for the determination of 0.01–0.80 μg ml^?1 nitrite. The reactions are very fast and require no control of temperature. The observed molar absorptivity and Sandell's sensitivity of the azo dye are 4.9 × 10⁴ l mol^?1 cm^?1 and 9.4 × 10^?4 μg cm^?2, respectively. The method is free from most interferences. The method has been applied successfully to polluted river water.     

Phenanthroline method for quantitative determination of surface carboxyl groups on carboxylated polystyrene particles with high sensitivity

This study developed a phenanthroline method for quantitative determination of surface carboxyl groups on carboxylated polystyrene (PS‐COOH) particles based on the coordination between the carboxyl groups and Fe²⁺. The ratio of the carboxyl groups, which is determined by conductometric titration method, to Fe²⁺ coordinated with the particles, which is determined by phenanthroline method, is 4.7, i.e. n_COOH = 4.7 × Δn_Fe²⁺. The Lambert–Beer law is obeyed in the range of 0–60 × 10^?9 mol/ml for the amount of surface carboxyl on the particles. The detection limit of the method is 2 nmol COOH/ml. The average standard deviation of the experiments is 4.4%. The relative deviation of the data obtained with this method is lower than 7% compared with that obtained with the conductometric titration method. The weight of the sample necessary for phenanthroline method is only about 0.1% of that necessary for conductometric titration method. It has been demonstrated that the phenanthroline method is suitable for quantitative determination of low amount of surface carboxyl groups on PS‐COOH particles due to its high sensitivity. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of 18F‐Difluoromethylarenes from Aryl (Pseudo) Halides

A general method for the synthesis of [¹⁸F]difluoromethylarenes from [¹⁸F]fluoride for radiopharmaceutical discovery is reported. The method is practical, operationally simple, tolerates a wide scope of functional groups, and enables the labeling of a variety of arenes and heteroarenes with radiochemical yields (RCYs, not decay‐corrected) from 10 to 60 %. The ¹⁸F‐fluorination precursors are readily prepared from aryl chlorides, bromides, iodides, and triflates. Seven ¹⁸F‐difluoromethylarene drug analogues and radiopharmaceuticals including Claritin, fluoxetine (Prozac), and [¹⁸F]DAA1106 were synthesized to show the potential of the method for applications in PET radiopharmaceutical design.     

Determination of Thallium in Soil

Abstract

A new spectrophotometric method is described for the determination of thallium in soil by extraction of Tl(III) with a toluene solution of N,N′-diphenylbenzamidine after acidification with 0.2–4.0 M HCl, and reaction of the extract with Crystal violet in the presence of 0.01–0.8 M HCl. The value of molar absorptivity of Tl(III)-X-CV complex (where X = Cl or Br; CV = Crystal violet) in toluene is 7.00 × 10⁴ 1 mole^?1 cm^?1 at the absorption maximum of 610 nm. The detection limit of the method is 20 ng ml^?1. The present method is free from interference of almost metal ions commonly associated with Tl. The method has been applied for analysis of the metal to soils.