Joanna Karpińska

Derivative spectrophotometry—recent applications and directions of developments

Various aspects of application of derivative spectrophotometry in chemical analysis and in investigations of equilibria and kinetics of reactions are scrutinised. The presented paper provides useful information about state-of-the-art and possibilities offered by derivative spectrophotometry in pharmaceutical, clinical or environmental fields of analysis.

ANALYTICAL STUDY OF THE REACTION OF PHENOTHIAZINES WITH SOME OXIDANTS, METAL IONS, AND ORGANIC SUBSTANCES (REVIEW ARTICLE)

Phenothiazines substituted in the 2 and 10 positions exhibit many valuable analytical properties. They are easily oxidized in acidic medium with a number of oxidants, e.g., K2Cr2O7, NH4VO3, Ce(SO4)2, KBrO3, KIO3, KIO4, NaNO2, H2O2, and chloramine T, with the formation of colored oxidation products. This property enable certain phenothiazines to be used as redox indicators for the determination of Fe(II), Sn(II), U(IV), Mo(V), ascorbic acid, etc. Oxidation reactions of phenothiazines were also used for their determination by spectrophotometric and flow injection methods. Some ions, such as iron, vanadium, iodide, or nitrite have a catalytic effect on the oxidation of phenothiazines. Owing to these properties several catalytic methods for the determination of metals, iodide, and nitrite have been proposed. Phenothiazines react in acidic media with platinum metals, e.g., Pd(II), Ru(III), and Pt(IV), the formation of colored complexes. They also react with thiocyanate anionic complexes of metals, e.g., Co(II), Pd(II), Fe(III), Bi(III), Cr(III), Ti(IV), Nb(V), Mo(V), and U(VI). Some organic substances (e.g., picric acid, flavianic acid, alizarin S, titan yellow, brillant blue, pyrocatechol violet) form with phenothiazines colored ion-association compounds sparingly soluble in water. These complexes are the basis for an extractive spectrophotometic determination of some metals or phenothiazines.

Simultaneous determination of zinc(II), manganese(II) and iron(II) in pharmaceutical preparations.

The applicability of derivative spectrophotometry for simultaneous determination of zinc(II), manganese(II) and iron(II) in the form of PAR complexes was presented and discussed. Beers law was obeyed in range 0.025-13 ppm for zinc 1-20, for manganese and 0.025-0.2 for iron ion. The elaborated method was applied successfully for determination of mentioned ions in pharmaceutical preparation without previous separation. The error of the determination did not exceed +/-3%.

Simultaneous LC determination of some antidepressants combined with neuroleptics

A reversed-phase HPLC method with UV detection at 252 nm is presented for the simultaneous determination of some tricyclic antidepressants (amitriptyline, imipramine) and neuroleptics (chlorprothixene, thioridazine) in their quaternary mixtures. Sample analysis was performed on a bonded reversed phase C-18, 5 microm, 250 x 4.6 mm ID (Lichrospher 100RP-18) column using acetonitrile and 0.01 M aqueous solution of triethylamine (1:1) as the mobile phase at 0.9 ml/min. The pH was adjusted to 2.7 with concentrated phosphoric acid. The retention time was for imipramine, amitriptyline, chlorprothixene, and thioridazine 5.8, 6.5, 8.3, 10.8 min, respectively. The linearity was obeyed up to 15 ppm for imipramine and amitriptyline, 12 ppm for chlorprothixene and 10 ppm for thioridazine. The presented method also allows the determination of the mentioned drugs individually in their pharmaceutical preparations.

The Use of Internal Standard Method for Dertvative-Spectrophotometric Determination of Chlorpromazine Hydrochloride

ABSTRACT The use of 1, 10-phenantroline as internal standard (IS) is proposed for spectrophotometric determination of chlorpromazine hydrochloride in pharmaceutical formulations. The spectra of both compounds: analyte and internal standard are partially overlapped, so the Savitzky-Golay alghoritm was used to obtain separated signals of analyte and IS. The best parameters to generate the second-derivative spectra were: ∠λ = 10 nm (5 experimental points) and second polynomial degree. For quantification of chlorpromazine in pharmaceuticals, the zero-crossing technique was used. The values of the second-derivative peaks were measured for chlorpromazine at 256 nm and at 236 nm for IS. Analytical characteristic for proposed method was evaluated (r2=0.9990, detection limit=3.97 ng/ml). The obtained analytical results were in good agreement with results obtained using the UV-spectrophotometric Blazek method.

THE SPECTROPHOTOMETRIC SIMULTANEOUS DETERMINATION OF AMITRYPTYLINE AND CHLORPROMAZINE HYDROCHLORIDES IN THEIR BINARY MIXTURES

The application of the Vierordts method and derivative spectrophotometry for simultaneous determination of amitryptyline (AMT) and chlorpromazine (CPM) hydrochlorides in their binary mixtures are presented. Both methods allow to determine the components without their isolation. By derivative spectrophotometry, amitryptyline hydrochloride can be determined in the range of 2–15 μg/ml and chlorpromazine hydrochloride between 2–53 μg/ml. The acceptable error was obtained when the ratio analyte:second component ranges from 3:1 to 50:1 for amitryptyline and 0.1 : 1–0.8 : 1 for chlorpromazine. The Vierordts method can be applied for resolution of the studied mixture when the ratio analyte : second component is in the 3:1–45:1 and 11:1–57:1 range for amitryptyline and chlorpromazine, respectively.

Investigation of novel material for effective photodegradation of bezafibrate in aqueous samples

A novel composite with an enhanced photocatalytic activity was prepared and applied to study the removal of bezafibrate (BZF), a hypolypemic pharmaceutical, from an aqueous environment. For the enhancement of titanium dioxide photoactivity a fullerene derivative, 2-(ferrocenyl) fulleropyrrolidine (FcC60), was synthesized and applied. Obtained composite was found to show a higher catalytic activity than pristine TiO2. Therefore, high hopes are set in composites that are based on carbonaceous nanomaterials and TiO2 as a new efficient photocatalysts.

Photocatalytic Decolourization of Direct Yellow 9 on Titanium and Zinc Oxides

The photodecolourization of Direct Yellow 9, a member of the group of azo dyes which are commonly used in the various branches of the industry, was investigated. The photostability of this dye was not previously examined. Photocatalytic degradation method was evaluated. Solar simulated light ( W/m2), titanium dioxide, and zinc oxide were used as irradiation source and photocatalysts, respectively. Kinetic studies were performed on a basis of a spectrophotometric method. Degradation efficiency was assessed by applying high performance liquid chromatography. Disappearance of a dye from titanium dioxide and zinc oxide surfaces after degradation was confirmed by thermogravimetry and Raman microscopy. Direct Yellow 9 was found to undergo the photodegradation with approximately two times higher efficiency when zinc oxide was applied in comparison with titanium dioxide. A simple and promising way to apply the photocatalytic removal of Direct Yellow 9 in titanium dioxide and zinc oxide suspensions was presented.

Simultaneous Determination of Levomepromazine Hydrochloride and Its Sulfoxide by UV‐Derivative Spectrophotometry and Bivariate Calibration Method

Abstract Two spectrophotometric methods are proposed for the simultaneous quantification of levomepromazine hydrochloride (LV) and its main degradation product levomepromazine sulfoxide (LV‐SO). One of them is based on the first order derivative spectra generated by the Savitzky‐Golay algorithm (third‐order polynomial degree, Δλ=10 nm). Determination of levomepromazine hydrochloride and its sulfoxide was realized by measurements of amplitudes of derivative spectra at 332 nm and 278 nm, respectively. The Beer law was obeyed in the concentration range 1.5–50 µg/mL for LV and 2.5–50 µg/mL for LV‐SO. The second of the proposed methods utilized the bivariate calibration algorithm. The determination was performed at 302 nm for levomepromazine and at 334 nm for sulfoxide. The elaborated methods allowed determination of LV in the concentration range 1.0–25 µg/mL while LV‐SO was determined in the concentration range 2.0–50 µg/mL.

Analytical problems with the determination of coenzyme Q10 in biological samples

The article discusses analytical problems related to the determination of coenzyme Q10 in biological samples. The assaying of coenzyme Q10 in complex samples, such as plasma, tissues, or food items requires meticulous sample preparation prior to final quantification. The process typically consists of the following steps: deproteinization, extraction, and ultimately reduction of extract volumes. At times drying under a gentle stream of neutral gas is applied. In the case of solid samples, a careful homogenization is also required. Each step of the sample preparation process can be a source of analytical errors that may lead to inaccurate results. The main aim of this work is to point to sources of analytical errors in the preparation process and their relation to physicochemical properties of coenzyme Q10. The article also discusses ways of avoiding and reducing the errors.