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1.
Two simple, fast, accurate and precise methods for the determination of six phenothiazines and a number of their pharmaceutical
formulations are described. The titrimetric method involves the oxidation of the drugs by metavanadate in sulphuric acid medium
and titration of vanadium(IV) formed, with cerium(IV) using ferroin indicator and acetone as catalyst. In spectrophotometry,
vanadium(IV) formed was reacted with ferriin and the resulting ferroin measured at 510 nm. Phenothiazines in the ranges 5–100 mg
and 2.5–25.0 μg mL−1 can be determined by titrimetry and spectrophotometry, respectively, with detection limits of 0.96–2.05 mg and 0.0359–0.0565 μg mL−1, respectively. Both methods were applied successfully to the determination of the studied drugs in pharmaceutical preparations.
The reliability of the assays was established by parallel determination by the official methods of British Pharmacopoeia and
the results being statistically evaluated.
Received September 26, 2000. Revision March 25, 2001. 相似文献
2.
Spectrophotometric Determination of Prochlorperazine Maleate in Pure and Pharmaceutical Preparations
Tehseen Aman Zeeshan Majeed Asrar Ahmad Kazi Islam Ullah Khan 《Mikrochimica acta》2002,138(1-2):13-17
Prochlorperazine maleate reacts with 1-naphthylamine and sodium nitrite, after heating for 110 s at 80 °C to give an orange
red colour having maximum absorbance at 460 nm. The reaction is selective for prochlorperazine maleate with 0.01 mg/mL as
visual limit of quantitation and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer’s
law from 0.01 mg/10 mL to 0.33 mg/10 mL of prochlorperazine maleate and the relative standard deviation is 0.68%. The quantitative
assessment of tolerable amounts of other drugs is also studied.
Received September 22, 2000. Revision June 19, 2001 相似文献
3.
Tehseen Aman Shamma Firdous Islam Ullah Khan Asrar Ahmad Kazi 《Mikrochimica acta》2001,137(3-4):121-126
Phenytoin sodium reacts with o-nitrobenzoic acid in alkaline media after heating for 10 minutes at 70 °C, to give a red coloured
complex having maximum absorbance at 510 nm. The reaction is selective for phenytoin sodium with 0.01 mg/10 mL as visual limit
of quantitation and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer’s law from
0.01 mg to 3 mg/10 mL of phenytoin sodium and the relative standard deviation is 0.29%. The quantitative assessment of tolerable
amounts of other drugs is also studied.
Received May 2, 2000. Revision May 11, 2001. 相似文献
4.
Three simple and sensitive colorimetric methods (A–C) for the determination of melatonin in bulk samples and in pharmaceutical
formulations are described. They are based on the formation of coloured species by reaction of ninhydrin with the drug (method
A, λmax 397 nm) by oxidation of the indol moiety in melatonin with potassium persulphate (method B, λmax 450 nm) or by reduction of osmium (VIII) (method C, λmax 516 nm). Regression analysis of Beer-Lambert plots showed good correlations in concentration ranges between 0.8–14.2, 70.0–140.0
and 2.0–40.0 μg/mL for methods A, B and C, respectively. The molar absorptivity, Sandell sensitivity and detection limit were
calculated. For more accurate analysis, Ringbom optimum concentration ranges were calculated. The validity of the proposed
methods was tested by analysing pharmaceutical formulations containing melatonin. The relative standard deviations were ≤ 0.95%
with recoveries 99.0–101.33%.
Received October 20, 1999. Revision February 10, 1999. 相似文献
5.
Ali Z. Abu Zuhri Nidal A. Zatar Raqi M. Shubietah Hala H. Arafat 《Mikrochimica acta》2000,134(3-4):153-160
Two methods are described for quantitative determination of nizatidine. The first is a cathodic stripping voltammetric method
which is based on the accumulation of the compound at the hanging mercury drop electrode. The adsorptive stripping response
was evaluated with respect of accumulation time, potential, concentration, pH and other variables. A linear calibration graph
was obtained over the range 3.0×10−8–1.0×10−6 M with a detection limit 3.0×10−8 M after a 20s accumulation time at −0.2 V accumulation potential. On the other hand, it was found that the detection limit
could be lowered to 1.0×10−8 M after 180s accumulation time at −0.2 V accumulation potential. The relative standard deviation was in the range 1.2−2.0%
for six measurements. The tolerance amounts of the common excipients have also been reported.
The second is a spectrophotometric method which is based on the formation and extraction of the ion-pair complex formed between
nizatidine and either bromocresol green or bromothymol blue. The extracted colored ion-pair complexes absorb at 416 nm. The
effect of different factors such as: type of organic solvent, pH, reagent concentration, number of extraction times, shaking
time, temperature and the tolerance amount of the common excipients have been reported. The calibration graph was linear in
the range 6.0×10−7–1.8×10−5 M with a detection limit of 6.0×10−7 M and molar absorptivity of 2.1×104 lċmol−1ċcm−1 when using bromocresol green, while the calibration graph was linear in the range 3.0×10−7–1.1×10−5 M with a detection limit of 3.0×10−7 M and molar absorptivity of 3.2×104 lċmol−1ċcm−1 when using bromothymol blue. The spectrophotometric methods offer alternative methods with reasonable sensitivity, selectivity
and accuracy with relative standard deviation in the range 2.1−6.0% and 1.2−4.7% (for six measurements) when using bromothymol
blue and bromocresol green, respectively. The proposed two methods were applied for the determination of nizatidine in commercially
available dosage forms. A comparison between the voltammetric and the extraction-spectrophotometric methods was also reported.
Received April 19, 1999. Revision August 30, 1999. 相似文献
6.
A procedure for the colorimetric assay of praziquantel has been developed. The method is based on the formation of charge-transfer
complexes with p-chloranil (I), dichloronitrophenol (II), 2,3-dichloro-5,6 dicyano-p-benzoquinone (III), 7,7,8,8-tetracyanoquinodimethane
(IV) and tetracyanoethylene (V) as π-acceptors to give highly coloured species. The coloured products are measured spectrophotometrically
at 550, 425, 460, 844 and 393 nm for I, II, III, IV and V, respectively. Optimization of the different reaction conditions
is described. The colour system obeyed Beer’s law in non-aqueous media in the concentration range 2.0–48 μg ml−1. It was stable for at least 4.0 h. The detection limit was found to be 0.6 μg ml−1. Applications of the procedure to the analysis of various pharmaceutical samples gave reproducible and accurate results.
Further, the validity of the procedure was confirmed by applying the standard addition technique. The total average recovery
was 100.2%.
Received June 10, 2000. Revision December 23, 2000. 相似文献
7.
Four simple and sensitive visible spectrophotometric methods (A–D) have been described for the assay of nimesulide (NMD)
either in pure form or in pharmaceutical formulations. Methods A and B are based on the oxidative coupling between the reduced
product of NMD (RNMD) and p-N,N-dimethyl phenylenediamine dihydrochloride (DMPD) in presence of chloramine – T (CAT) or 3-methyl-2-benzothiazolinone
hydrazone hydrochloride (MBTH) in presence of ferric chloride (Fe III) to form coloured products with λmax at 540 nm and 600 nm respectively. Method C is based on the diazotization of RNMD with excess nitrous acid (HNO2) and estimating the consumed HNO2 with cresyl fast violet acetate (CFVA). Method D is based on the formation of the coloured charge-transfer complex, when
RNMD is treated with metol (p-methyl aminophenol sulphate, PMAP) in presence of potassium dichromate. All variables have been
optimized and the reaction sequence is presented. The concentration measurements are reproducible within a relative standard
deviation of 1.0%. Recoveries are 98.6–100.2%.
Received February 5, 1998. Revision February 20, 1999. 相似文献
8.
《Analytical letters》2012,45(3):417-423
Abstract A spectrofluorimetric method was developed for the determination of gatifloxacin. The emission peak for gatifloxacin was recorded at 495 nm upon excitation at 291 nm. The fluorescence process was pH dependent. The dynamic range for the method was 16–80 ng ml?1with detection limit of 3.97 ng ml?1. A linear relationship between the fluorescence intensity and the concentration of gatifloxacin solution was obtained with r 2 of 0.9968. The method has successfully applied to the determination of gatifloxacin in pure, authentic and aqueous samples. 相似文献
9.
Two simple and sensitive methods for the determination of indapamide in pure and in dosage forms are developed. These methods
are based on the oxidation of indapamide with iron(III) in acidic medium. The liberated iron(II) reacts with 1,10-phenanthroline
(Method A) and the ferroin complex is colorimetrically measured at λmax 509 nm against reagent blank. Method B is based on the reduction of Fe(III) by the drug. Iron(II) forms a colored complex
(λmax 522 nm) with 2,2′-bipyridyl. Optimization of the experimental conditions is described. Beer’s law is obeyed in the concentration
range 1.0–12 μg ml−1 and 4.0–18 μ g ml−1 for A and B, respectively. The apparent molar absorptivity and Sandell sensitivity for method A is 3 × 104 L mol−1 cm−1 and 0.0188 μ g cm−2, while for method B is 2.3 × 104 L mol−1 cm−1 and 0.0159 μg cm−2. The detection and quantification limits are calculated. The developed methods are applied successfully for the determination
of indapamide in pure and in tablet form without interference from common excepients.
Received November 10, 2000. Revision April 6, 2001. 相似文献
10.
《Analytical letters》2012,45(16):1321-1334
Abstract Methotrexate, 4-amino-10-methyl folic acid, is one of the drugs belonging to the folic acid antagonists that is widely used for the treatment of cancer and psoriasis 1, 2 相似文献
11.
Carmen Cruces-Blanco Antonio Segura Carretero Silvia Fernández Peinado Alberto Fernández Gutiérrez 《Mikrochimica acta》2000,134(1-2):107-111
A spectrofluorimetric method for the determination of methyl paraben based on derivatization with the labelling reagent dansyl
chloride (DNS-Cl), is presented. The effect of the reaction variables (pH, DNS-Cl concentration, temperature, reaction time)
and instrumental parameters, has been examined. A linear calibration graph in the ng/ml range has been established. The limit
of detection is 18 ng/ml with relative standard deviation less than 3%. The proposed method has been satisfactorily applied
to determination of the paraben in two pharmaceutical preparations.
Received May 25, 1999. Revision October 20, 1999. 相似文献
12.
Cathodic adsorptive stripping voltammetry (CASV) was applied for the determination of rutin in pharmaceuticals, human urine,
and blood serum. An electrochemical stripping procedure for trace measurements of rutin was developed based on the adsorption
of the Cu2+-rutin complex on a hanging mercury drop electrode and applied to the quantification of the drug. Cyclic voltammetry was used
to characterize the interfacial and redox behavior of the adsorbed Cu2+-rutin complex. Experimental and instrumental parameters for quantitative determination were optimized, and a detection limit
of 4.9 × 10−9 mol · L−1 in presence of Cu2+-ions for quantification of rutin under optimum conditions was derived. The sharp peak of the adsorbed Cu2+-rutin complex associated with an effective interfacial accumulation of this compound facilitates the determination of rutin
in biological fluids with good recoveries. The degree of interference from potentially present metal ions and organic compounds
on the CASV signal for Cu2+-rutin complex was evaluated. 相似文献
13.
Ewa Bobrowska-Grzesik 《Mikrochimica acta》2001,136(1-2):31-34
Derivative spectrophotometry was applied for the simultaneous determination of amoxycillin and clavulanic acid in pharmaceutical
preparations: “Augmentin” inj. and tablets and “Amoksiklav” drops and tablets, in solutions after hydrolysis with sodium hydroxide.
As the absorption spectra overlap strongly (amoxycillin λmax = 247 nm and 290 nm, clavulanic acid λmax = 258 nm) the first and the second derivative spectrophotometric procedure was elaborated for their determination. Amoxycillin
was determined at λ = 257.9 nm (1-st derivative spectra) or λ = 273 nm (2-nd derivative) while clavulanic acid at λ = 280.3 nm
(1-st derivative) or λ = 285 nm (2-nd derivative spectra). The Beer’s law is obeyed in the range of 0.004–0.04 mg/ml for amoxycillin
and 0.002–0.02 mg/ml for clavulanic acid.
Received December 6, 1999. Revision August 1, 2000. 相似文献
14.
Leonardo Sena Gomes Teixeira Antônio Celso Spínola Costa Júlio César Rosa Assis Sérgio Luis Costa Ferreira Mauro Korn 《Mikrochimica acta》2001,137(1-2):29-33
A new sensitive method exploiting solid-phase spectrophotometry is proposed for the determination of cobalt in pharmaceutical
preparations. The chromogenic reagent 1-(2-thiazolylazo)-2-naphthol (TAN) was immobilized on C18 bonded silica loaded into
a home-made cell with 1.5 mm of optical path for cobalt determination. Cobalt(II) reacts with TAN on C18 material, at pH 6.0–7.5,
to give a coloured complex which has maximum absorption at 572 nm. In this way, the sample was passed through the cell and
Co(II) ions were quantitatively retained on the solid-phase. After the direct measurement of light-absorption in the solid
phase, only the cobalt was eluted with 0.1 mol L−1 hydrochloric acid. The cell was washed with water and then another sample solution could be passed through the cell. The
procedure allowed the determination of cobalt in the range of 10–160 μg L−1 with coefficient of variation of 4.7% (n=10) and apparent molar absorptivity of 2.62 × 106 L mol−1 cm−1 using sample volume of 3-mL.
Received May 15, 2000. Revision August 28, 2000. 相似文献
15.
A rapid and quantitative procedure for the determination of dithionite based on the reduction of naphthol yellow S in ammonia
containing solution and measurement of the absorbance of the product formed at 502 nm is described. The mechanism of the reaction
is discussed and its analytical application is shown to be possible in a concentration range of dithionite between 16.7 and
133.1 mg l−1 (1.3 × 10−4 and 1.04 × 10−3 mol l−1). The procedure was applied to the determination of dithionite in commercial formulations used in the household. In a 0.5 g
sample of decolorant, dithionite was found to be present at concentrations between 25 and 35% (w/w), which can be determined
without interference of its decomposition products. The results are shown to be in good agreement with those of polarographic
determinations.
Received April 26, 2001. Revision August 2, 2001. 相似文献
16.
Pilar Viñas Carmen López-Erroz Francisco Joseé Cerdán Natalia Campillo Manuel Hernández-Córdoba 《Mikrochimica acta》2000,134(1-2):83-87
A new fluorimetric procedure for the determination of thiamine using flow injection analysis is proposed. The method is based
on the derivatization reaction of the primary amine group with o-phthalaldehyde in the presence of 2-mercaptoethanol using fluorimetric detection. The calibration graph based on peak area
was linear in the range 0.2–6 ng mL−1. The detection limit was close to 0.1 ng mL−1. The method was applied to the determination of the vitamin in commercial pharmaceutical preparations.
Received March 31, 1999. Revision October 15, 1999. 相似文献
17.
Islam Ullah Khan Tehseen Aman Muhammad Asif Iqbal Asrar Ahmad Kazi 《Mikrochimica acta》2000,134(1-2):27-31
Fluoxetine hydrochloride reacts with benzoyl peroxide and potassium iodide, after heating for 1 min at 30 °C, to give a blue
colour having maximum absorbance at 570 nm. The reaction is selective for fluoxetine with 0.01 mg/mL as visual limit of quantitation
and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer’s law from 0.1 mg/10 mL to
2.0 mg/10 mL of fluoxetine and the relative standard deviation is 0.68%. The qualitative assessment of tolerable amounts of
other drugs is also studied.
Received September 21, 1998. Revision September 10, 1999. 相似文献
18.
The anodic polarographic behaviour of nilvadipine was studied by using direct-current (DC), polarography and differential-pulse
polarography (DPP). Nilvadipine, being a dihydropyridine derivative, exhibits well-defined anodic waves over the whole pH
range of the Britton-Robinson buffers (BRb). In BRb of pH = 4, the diffusion-current constant was 6.45 ± 0.07 μA · mM−1. The current-concentration plots are rectilinear over the ranges 1.6–12.8 and 0.2–12.8 μg/ml for DC polarography and DPP,
respectively, with minimum detectability of 0.05 μg/ml (1.3 × 10−7 M) in case of the latter technique. The proposed method was successfully applied for determination of the drug in commercial
capsules containing the drug, the percentage recoveries being in good agreement with the label claim. Furthermore, the method
was applied for the determination of the drug in spiked human urine, the percentage recovery being 96.84 ± 2.83.
Received January 25, 2001 Revision June 18, 2001 相似文献
19.
Combined analytical procedures consisting of wet digestion step followed by instrumental determination – differential pulse
cathodic stripping voltammetry (DPCSV) or electrothermal atomic absorption spectrometry (ETAAS) – as well as a direct analysis
method – slurry sampling ETAAS – for the determination of Cd, Co, Cr, Cu, Fe, Ni and Pb in milk, cheese and chocolate are
described and compared. Wet digestion using a mixture of HNO3-HClO4-H2O2 is proposed for complete matrix decomposition prior to trace analyte determinati on by DPCSV or ETAAS. A mixture of HNO3-H2O2 is used for slurry preparation. Optimal instrumental parameters for trace analyte measurements are presented.
The reliability of the procedures has been verified by analyzing standard reference materials. Results obtained are in good
agreement with the certified values and the relative standard deviations (for these results) are in the range 5–10% for wet
digestion DPCSV or ETAAS and 3–9% for slurry sampling ETAAS in the range of 2 μgċg−1 (Cd) to 12 μgċg−1 (Fe).
Received August 24, 1999. Revision January 20, 2000. 相似文献
20.
Saadia M. El-Ashry Fathalla Belal Mohamed M. El-Kerdawy Dalia R. El Wasseef 《Mikrochimica acta》2000,135(3-4):191-196
A simple and sensitive spectrophotometric method is described for the determination of some phenolic antibiotics namely:
cefadroxil, amoxicillin and vancomycin. The method is based on the measurement of the orange yellow species produced when
the drugs are coupled with diazotized benzocaine in triethylamine medium. The method is applicable over the range of 0.8–12 μg/ml
for cefadroxil, 2–16 μg/ml for amoxicillin and 2–18 μg/ml for vancomycin. The formed compounds absorb at 455 nm for both cefadroxil
and amoxicillin and at 442 nm for vancomycin. The proposed method has detection limits of 0.018 μg for cefadroxil, 0.0034 μg
for amoxicillin and 0.0156 μg for vancomycin.
The stoichiometric ratio for the studied compounds was found to be 1:1 and a proposal of the reaction pathway was made. The
proposed method was applied for the analysis of the cited drugs in their pharmaceutical preparations. The results are in good
agreement with those obtained by the official methods.
Received February 7, 2000. Revision June 14, 2000. 相似文献