An easy and short-time TLC-densitometric method was developed for the separation of metronidazole, secnidazole, ornidazole, tinidazole, and 2-methyl-5-nitroimidazole and for the determination of metronidazole and tinidazole in Metronidazole Polpharma and Tinidazolum Polpharma tablets. Analyzes were performed on chromatographic plates precoated with silica gel 60F254 using the optimal mobile phase: chloroform + methanol + diethylamine in a volume ratio of 9:1:1. The method has been validated. The intraday and interday precision values for the three different concentrations ranged from 0.99% to 1.48% and 0.89% to 1.76%, and the precision values ranged from 1.13% to 2.48% and 0.95% to 2.49% for metronidazole and tinidazole, respectively. The limit of quantification (LOQ) was 0.036 and 0.066 µg/spot for metronidazole and tinidazole, respectively. The mean recovery was 103.1% and 100.6% for metronidazole and tinidazole, respectively. The content of metronidazole and tinidazole in tablets in relation to the content declared by the manufacturer was 101.3% and 99.8%, respectively. The obtained results were verified using the pharmacopoeial method. The presented method is fast, sensitive, precise, selective, accurate and robust. It allows for the analysis of several samples on one chromatography plate at the same time.

TLC and HPTLC in normal (NP) and reversed (RP) phase systems combined with densitometry were used to analyze caffeine, propyphenazone and paracetamol. Normal phase analyses were performed on five different stationary phases (chromatographic plates), testing three mobile phases. Reversed-phase analyses were performed on four different chromatographic plates using three mobile phases. Thus, it was checked whether analyses using TLC chromatographic plates could be as sensitive as those performed on HPTLC plates. For all analyzed biologically active substances, the limit of detection (LOD) was calculated, i.e. a parameter that describes the method sensitivity. It has been shown that using both TLC and HPTLC plates, it is possible to develop chromatographic conditions that enable the detection of caffeine, propyphenazone and paracetamol in amounts ranging from a dozen to several dozen µg/spot. In the reversed-phase (RP) system, lower LOD values for all tested compounds were obtained using TLC than HPTLC. However, using analyses in the normal phase system (NP), similar (of the same order) LOD values are obtained for caffeine, propyphenazone and paracetamol, both when using TLC and HPTLC plates. Therefore, for economic reasons, TLC plates should be recommended for analyses of caffeine, propyphenazone and paracetamol, which are several times cheaper than HPTLC plates.

New TLC-densitometric method have been developed for the identification and quantification of paracetamol (PA), propyphenazone (PP) and caffeine (C) of Saridon tablets using the NP-TLC technique combined with densitometry. This method allows for the simultaneous determination of PA, PP, and C in the same sample. Among all tested chromatographic conditions, the mixture consisting of chloroform + toluene + ethyl acetate + ethanol + acetic acid (18:18:7.5:5.0:0.3, v/v) and silica gel 60F254 plate proved to be the most effective for the separation of three tested active pharmaceutical ingredients (APIs) and substances related to paracetamol. The fully validation of the proposed NP-TLC method proves that it is specific, precise, accurate, robust and sensitive. The percentage content in relation to the content declared by the manufacturer is for propyphenazone 99.8%, paracetamol 101.6% and caffeine 100.8%, which are in accordance with pharmacopoeial requirements. The results presented indicate the possibility of using the developed method in the routine control of pharmaceutical preparations containing these APIs. The proposed method is economical and more sensitive compared to the previously proposed planar methods for the simultaneously determination of PA, PP and CAPIs. Will be an What is more, the presented method may be anaxcellent excellent economical alternative when HPLC method is unavailable for such determination.

This study explores the dynamics of liquid holdup in a lab-scale co-current two-phase upflow moving packed bed reactor, specifically examining how superficial gas velocity influences the line average external liquid holdup at a fixed superficial liquid velocity. Utilizing Gamma-ray Densitometry (GRD) for precise measurements, this research extends to determining line average internal porosity within catalyst particles and the overall external bed porosity. Conducted with an air-water system within a bed packed with 3 mm extrudate porous particles, the study presents a novel methodology to calculate liquid holdup, grounded in Beer–Lambert's law. Findings reveal a decrease in liquid holdup corresponding with increased superficial gas velocity across axial and radial locations, with a notable transition from bubbly to pulse flow regime at a critical velocity of 3.8 cm/sec. Additionally, the lower sections of the packed bed exhibited higher external liquid holdup compared to the middle sections at varied gas velocities. The liquid holdup distribution appeared uniform at lower flow rates, whereas higher flow rates favored the middle sections.