scholarly journals HYDROPHOBIC AROMATIC THIO (DITHIO)COMPOUNDS AS CHROMOGENIC ANALYTICAL REAGENTS FOR PHOTOMETRIC DETERMINATION OF THIOLS BY MERCAPTO GROUP II. A UNIFIED MOLECULAR MODEL OF THE ANALYTICAL REAGENT

2020 ◽  
Vol 55 ◽  
pp. 49-57
Author(s):  
Kirill V. Veksler ◽  
◽  
Evgenia N. Volkova ◽  
Alexander G. Gontсharenko ◽  
◽  
...  
Keyword(s):  
Reaction Center ◽  
Molecular Model ◽  
Spectral Characteristics ◽  
Photometric Determination ◽  
Azo Compounds ◽  
Substitution Reactions ◽  
Mercapto Group ◽  
Sh Reagents ◽  
Analytical Reagents ◽  
Analytical Reagent

The concept of a unified molecular model is proposed for the directed synthesis of chromogenic analytical reagents for the mercapto group in ("thiol-thiol") substitution reactions (SH reagents). The unified molecular model of the SH reagent includes an aromatic chromophore-containing thio fragment covalently bound by an ordinary bond on a sulfide sulfur atom to an electrophilic, relatively soft one [in terms of the principle of hard and soft acids and bases (the HSAB principle)] reaction center. The characteristics of the analytical effect of the SH reagent are determined by the structure of the thio fragment. The required change in the reactivity and selectivity of the SH reagent are achieved mainly by varying the softness (stiffness) of the reaction center. Spectral characteristics of analytical effects, reactivity and selectivity of SH reagents (obtained earlier and synthesized for the first time in this work) – hydrophobic aromatic thio (dithio) compounds: thiocyanates, symmetric disulfides, and thiomercuric compounds – were studied in an aprotic dipolar DMF medium. In support of the concept of the unified molecular model for compounds containing identical thiofragments it was established: - spectral characteristics of the analytical effect of all three types of compounds (thiocyanates, disulfides and thiomercuric compounds) are the same in the DMF medium. - in accordance with the principle of HSAB, the reactivity increases in the sequence thiocyanate < disulfide <<thiomercuric compound, which corresponds to an increase in the softness of the reaction center in the series: -С << - S-<< -Hg-. The universality of the concept of the unified molecular model follows from consideration of the spectral and kinetic characteristics not only of Ellman reagent, but as well of thio(dithio)azo compounds, thiocyanate and thiomercuric compound containing the same 3-carboxy, 4-nitrophenylthio fragment.

scholarly journals 2-(piperidinomethyl) -4-methylphenol as an Analytical Reagent for Extraction-photometric Determination of Iron (III)

2020 ◽  
Vol 35 (3) ◽  
pp. 111-118
Author(s):  
A.Z. Zalov ◽  
◽  
Ch.K. Rasulov ◽  
K.A. Kuliev ◽  
G.I. Ibragimov ◽  
...  
Keyword(s):  
Photometric Determination ◽  
Analytical Reagent

Simultaneous Spectrophotometric Determination of Lamivudine and Stavudine using π-Acceptors as Analytical Reagents

2020 ◽  
Vol 5 (3) ◽  
pp. 234-241
Author(s):  
Sayanna ◽  
T. Veeraiah ◽  
Ch. Venkata Ramana Reddy
Keyword(s):  
Area Under Curve ◽  
Dosage Forms ◽  
Simultaneous Estimation ◽  
Determination Method ◽  
Chloranilic Acid ◽  
Spectrophotometric Methods ◽  
Analytical Reagents ◽  
Analytical Reagent ◽  
The Individual

Two new sensitive and precise spectrophotometric methods have been proposed and developed for the simultaneous estimation of lamivudine and stavudine in pure mixture and in pharmaceutical binary dosage forms. A new concept of area under curve (AUC) is proposed for simultaneous estimation of two drugs by these methods. Method A involves the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as analytical reagent and the AUC between 390 nm and 690 nm for DDQ was used for determination. Method B involves the use of p-chloranilic acid: 2,5-dichloro-3,6-dihydroxy-1,4- benzoquinone (p-CA) as an analytical reagent and the AUC between 400 and 700 nm for p-chloranilic acid was used for deter-mination. The methods developed and construction of calibration curves using two analytical reagents viz., DDQ and p-chloranilic acid are described. Optical and analytical parameters for the individual and simultaneous determination of lamivudine and stavudine using AUC are tabulated. The methods have been validated and compared with HPLC methods in terms of standard deviation, t-test and F-test.

scholarly journals 6,7- AND 7,8-DIHYDROXYBENZOPYRYLIUM DERIVATIVES: SYNTHESIS, PROPERTIES AND ANALYTICAL APPLICATION (REVIEW)

2021 ◽  
Vol 26 (2(78)) ◽  
pp. 48-55
Author(s):  
A. N. Chebotarev ◽  
S. V. Toporov ◽  
D. V. Snigur ◽  
D. A. Barbalat
Keyword(s):  
Atomic Absorption ◽  
Spectral Characteristics ◽  
Chemical Properties ◽  
Photometric Determination ◽  
Detection Methods ◽  
Micellar Phase ◽  
Highly Sensitive ◽  
Synthesis Properties ◽  
Composition Structure

The present review is devoted to a class of organic analytical reagents 6,7- and 7,8-dihydroxybenzopyrylium derivatives: their synthetic pathways, physicochemical properties, state in solutions, and analytical applications are described. Anion nature influence on spectral characteristics and some physico-chemical properties of 6,7-dihydroxybenzopyrylium derivatives was noted. Pathways of acid-base transformations in aqueous solutions of 6,7-dihydroxybenzopyrylium derivatives were described. It has been shown that derivatives of 6,7- and 7,8-dihydroxybenzopyrylium are capable for complexation with a number of p-, d-, and f-elements (Cu (II), Ga (III), In (III), Tl (III), Ge (IV), La (III), titanium subgroup, Bi (III), Mo (VI), W(VI) and others). Information on their composition, structure and analytical characteristics is summarized. It is noted that with the 6,7-dihydroxybenzopyrylium derivatives the simple and highly sensitive methods for the direct spectrophotometric and extraction-photometric determination of Ga(III), In(III), Tl(III), Ti(IV), Zr(IV), Hf(IV), Mo(VI), Ge(IV), Bi(III), Cu(II) have been developed. It is noted that 6,7-dihydroxybenzopyrilium derivatives complexes with Mo(VI) and Cu(II) are effectively extracted by Triton X‑100 micellar phase, which forms the basis for highly sensitive combined spectrophotometric and atomic absorption methods for their determination. The simplicity of targeted synthesis of 7,8- and 6,7-dihydroxybenzopyrylium derivatives opens the way to their use in the development of combined cloud point extraction and liquid-liquid microextraction with spectrophotometric or atomic absorption detection methods for the determination of a number of p- and d-elements.

Simultaneous Spectrophotometric Estimation of Azithromycin and Ofloxacin using π-Acceptors as Analytical Reagents

2020 ◽  
Vol 13 (5) ◽  
pp. 5082-5089
Author(s):  
Veeraiah T ◽  
Ravi M ◽  
Ch Venkata Ramana Reddy
Keyword(s):  
Simultaneous Determination ◽  
Area Under Curve ◽  
Dosage Forms ◽  
Simultaneous Estimation ◽  
Chloranilic Acid ◽  
Spectrophotometric Methods ◽  
Analytical Reagents ◽  
Analytical Reagent ◽  
The Individual

In this study, two sensitive and precise spectrophotometric methods have been developed for the simultaneous determination of azithromycin and ofloxacin in pure mixture and in pharmaceutical binary dosage forms. A new concept of area under curve (AUC) is proposed for simultaneous estimation of two drugs by these methods. Method A involves the use of DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) as analytical reagent and the AUC between 390nm and 690nm for DDQ was used for determination. Method B involves the use of p-CA (p-chloranilic acid: 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) as an analytical reagent and the AUC between 400nm and 700nm for p-CA was used for determination. The methods developed and construction of calibration curves using two analytical reagents viz., DDQ and p-CA are described. Optical and analytical parameters for the individual and simultaneous determination of azithromycin and ofloxacin using AUC are tabulated. These methods have been validated and compared with HPLC methods in terms of standard deviation, t-test and F-test.

Sign in / Sign up

Export Citation Format

Share Document