The frustrated reviewer — Recurrent failures in manuscripts describing validation of quantitative TLC/HPTLC procedures for analysis of pharmaceuticals

Summary. Transfer of two rapid thin-layer chromatography (TLC) screening methods used to detect markedly substandard and fake pharmaceutical products to quantitative high-performance TLC (HPTLC)-densitometry methods is demonstrated using a model procedure that was published earlier. These TLC methods for diazepam and amodiaquine are contained in a Compendium of methods by Kenyon and Layloff and a Minilab method manual from Global Pharma Health Fund E.V., respectively, for use in countries with limited resources. Merck HPTLC Premium Purity silica gel 60 F 254 glass plates, automated standard and sample solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 were used for detection, identification, and quantification. Sample peak identity and purity validation were carried out by spectral comparison checks available in the winCATS software. Accuracy was estimated by the standard addition approach with overspotting standard and sample solutions. HPTLC gives better efficiency, selectivity, and resolution than TLC, and the new methods overcome the deficiencies in technology related to manual application and visual zone comparison that do not allow the Compendium and Minilab TLC procedures to support regulatory compliance actions. These new methods can be fully validated according to the International Conference on Harmonization guidelines or by interlaboratory studies if required by their applications.

Section: Discussionmentioning

confidence: 99%

Transfer of TLC screening methods designed for use in developing countries to quantitative HPTLC-densitometry methods for diazepam and amodiaquine tablets

Popovic¹,

Sherma²

2014

“…It has been shown that, with some additional training, some operators in these countries can competently perform HPTLC-densitometry [5,14] and obtain much more information and better results compared to visual semiquantitative TLC methods. If necessary, full validation of the developed HPTLC-densitometry quantitative methods can be performed according to International Conference on Harmonization (ICH) guidelines for HPTLC pharmaceutical analysis [15,16], including accuracy, precision (repeatability and intermediate precision), specificity, linearity, range, and robustness.…”

Section: Discussionmentioning

confidence: 99%

A model procedure for the transfer of TLC pharmaceutical product screening methods designed for use in developing countries to quantitative HPTLC-densitometry methods

O'Sullivan¹,

Sherma²

2012

Summary.Transfer of four rapid thin-layer chromatography (TLC) screening methods used to detect substandard and counterfeit pharmaceutical products to quantitative high-performance TLC (HPTLC)-densitometry methods is demonstrated. These methods for acetaminophen, acetylsalicylic acid, ibuprofen, and chlorpheniramine maleate are contained in a Compendium of methods developed by Kenyon and Layloff for use in countries with limited resources. The new quantitative methods use Merck HPTLC silica gel 60 F 254 glass plates, automated standard and sample application, and automated densitometry for detection, identification, and quantification. Standard and sample solution preparation and application procedures for obtaining calibration curves and bracketed samples are described. The HPTLC plates give better efficiency, selectivity, and resolution than TLC, and the new methods overcome the deficiencies in technology related to manual application and visual zone comparison that do not allow the Compendium TLC procedures to support regulatory compliance actions. These transferred methods can be fully validated according to International Conference on Harmonization (ICH) guidelines or by interlaboratory studies if their applications require. The approach described can be used to transfer the remaining Compendium methods as well as the GPHF [Global (formerly German) Pharma Health Fund E.V.] Minilab kit TLC screening methods.

“…The optimized method was validated for the determination of sulfasalazine in the presence of its impurities according to the International Conference on Harmonization (ICH) guidelines [10,11].…”

Section: Validation Of the Methodsmentioning

confidence: 99%

TLC—Densitometric Determination of Sulfasalazine and Its Possible Impurities in Pharmaceutical Preparations

Kwiecień

Piątek

Żmudzki

et al. 2015

Summary.A simple, selective, and sensitive thin-layer chromatographic-densitometric method has been developed for the determination of sulfasalazine besides its possible impurities in pharmaceutical preparations. The mobile phase was composed of ethyl acetate-methanol-ammonia 25% 10:7:3 (v/v/v), and the stationary phase was aluminum plates precoated with silica gel 60 F 254 that enabled to obtain well resolved peaks of sulfasalazine and its impurities. The developed chromatograms were analyzed densitometrically at λ = 360 nm. R F values and ultraviolet (UV) spectra were used to identify the compounds. The developed method is highly sensitive (limit of detection [LOD] = 17.11 ng spot −1 , limit of quantitation [LOQ] = 51.84 ng spot −1 ), precise (relative standard deviation [RSD] = 1.43%-4.28%), and accurate (RSD = 1.64%-4.27%). The linearity of the method was checked within the range 20-120 ng spot −1 . The method was successfully applied for the determination of sulfasalazine in pharmaceutical preparations besides its impurities. The structures of impurities present in the standard substance and in pharmaceutical preparations were established by ultra-performance liquid chromatographytandem mass spectrometry (UPLC-MS/MS) technique.