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  • Author or Editor: Arkadiusz Pomykalski x
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The cyclooxygenase inhibitors lornoxicam, meloxicam, piroxicam, and tiaprofenic acid have been separated by normal- and reversed-phase TLC by ascending and horizontal development with suitable mobile phases on silica gel and silanized gel. The substances were identified by UV illumination at λ = 254 nm and by use of dyeing reagents. Meloxicam and tiaprofenic acid were determined in pharmaceutical preparations by videodensitometric TLC on silica gel and ascending development with toluene-acetic acid-methanol, 11 + 1 + 0.5 ( v/v ), as mobile phase. The range of linearity was 0.5–5.0 μg per spot for both drugs. The method was applied satisfactorily to pharmaceutical preparations. Results from quantitative analysis were assessed statistically by determination of the correlation coefficient for the calibration equation obtained from the calibration procedure. The RSD for quantitation of meloxicam and tiaprofenic acid were 5.8 and 5.9%, respectively.

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The chromatographic separation of fenbufen, ibuprofen, ketoprofen, diclofenac sodium, mefenamic acid, and tiaprofenic acid has been investigated. Normal-phase chromatography on silica gel by the ascending and horizontal techniques, and reversed-phase chromatography on octadecyl-bonded silica gel (RP-18) in horizontal chambers, were performed with suitable mobile phases. The substances were identified by UV illumination at λ = 254 nm and by use of dyeing reagents. Reversed phase chromatography with phosphate buffer, pH 5.73–10% CTMA-Br in methanol, 3.5 + 6.5 ( v/v ), as mobile phase enabled better separation of the six drugs than normal-phase mode. A simple videodensitometric TLC method on silica gel RP-18 was developed and validated for quantitative determination of fenbufen in tablets. The limits of detection and quantification were determined by videodensitometry at λ = 254 nm. A calibration plot was constructed in the range 2.0–12.0 μg/5-μL spot and was linear with a good correlation coefficient (0.9926). RSD for quantitation of fenbufen were from 2.44 to 3.10%. The method was applied satisfactorily to pharmaceutical preparations.

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3-Mercapto-5-(2′-hydroxynaphthylazo-1′)-1,2,4-triazole (metrian); 3-mercapto-5-(3′,4′-dihydroxyphenylazo-1′)-1,2,4-triazole (metriap); 3-mercapto-5-(2′,4′-dihydroxy-3′-carboxyphenylazo-1′)-1,2,4-triazole (metriarez-γ), and 2-mercapto-5-(2′,4′-dihydroxy-5′-carboxyphenylazo-1′)-1,3,4-thiadiazole (metidarez-β) have been used to determine, by different methods, milligram quantities of Fe(II) and Zn(II), present together in pharmaceutical preparations, both multivitamin preparations and preparations containing microelements. Results from ion chromatography (IC) were compared with those from classical spectrophotometry (D 0 ), derivative spectrophotometry (D 1 and D 2 ), and atomic absorption spectrometric (AAS). Results were analyzed statistically and compared with the declared amount. The advantages of the proposed method for determination of Fe(II) and Zn(II) include its excellent precision and the reproducibility of the results.

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A new, accurate, rapid TLC method has been established for determination of timolol maleate (Timohexal 0.1%, Timoptic 0.25%) and betaxolol hydrochloride (Betoptic 0.5%) in ophthalmic solutions. The selectivity of the separation of these drugs has been investigated by TLC on silica gel 60F 254 , silanized C 8 silica gel, and aluminum oxide 60 F 254 plates with ascending and horizontal development. Suitable conditions for separation were use of silica gel with ethyl acetate-methanol-25% aqueous ammonia, 80 + 18 + 2 ( v/v ), as mobile phase. The substances were visualized by UV irradiation at λ = 254 nm or by spraying with suitable reagents. Detection and quantification of timolol maleate and betaxolol hydrochloride were performed densitometrically at λ = 300 nm and λ = 218 nm, respectively, and videodensitometrically at λ = 254 nm. Results from quantitative analysis were statistically assessed by use of the calibration procedure, a calibration equation, the correlation coefficient ( R 2 ), and relative standard deviation.

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