Ibuprofen is one of the best-known nonsteroidal anti-inflammatory and analgesic drugs. Following the previous work, the current study is focused on estimating the effect of different chromatographic conditions on the sensitivity of thin-layer chromatography in combination with UV densitometry, i.e., the detection and quantification of ibuprofen in a wide range of its concentrations including the lowest limits of detection (LOD) and quantification (LOQ). For this purpose, a reliable and easy-to-use calculation procedure for LOD and LOQ determination is presented in this work. In addition, the impact of type plates and mobile phase composition on the LOD and LOQ, respectively, of this active substance is accurately described. The results of detection and the quantification level of ibuprofen obtained under applied chromatographic conditions confirmed the utility of silica gel plates as well as silica gel bonded phases (i.e., reversed-phase (RP) plates) in the thin-layer chromatography (TLC)-densitometric analysis of ibuprofen at a low level, i.e., from several nanograms (below one microgram) to a few micrograms/spot. Among all chromatographic systems tested, the best are those consisting of silica gel 60F₂₅₄ plates with concentrating zone (1.05583) and the mixture of n-hexane:ethyl acetate:glacial acetic acid in ratio 36:12:2 (v/v/v) as well as RP plates, i.e., RP-18F₂₅₄ aluminum plates developed with methanol:water in volume composition 40:10 (v/v). These chromatographic systems allowed quantifying ibuprofen in the amount of 0.229 µg/spot and 0.228 µg/spot, which is less than 1 µg/spot. It can be stated that different chromatographic systems in combination with UV densitometric scanning at 224 nm proposed in this work can be successfully applied for the cost-effective and sensitive determination of ibuprofen as a widely used drug component as well as a residual in domestic wastewater. It was found that the modification of silica gel as well as the layer thickness of unmodified or modified silica gel 60 can influence the quality of chromatograms and the detection/quantification of ibuprofen in both normal phase (NP) and RP systems. Therefore, to obtain the best possible LOD and LOQ values of ibuprofen with precoated layers, suitable mobile phase and chromatographic plates are required.

中文翻译：

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通过TLC-光密度法在不同色谱条件下估算布洛芬的检测和定量限

布洛芬是最著名的非甾体类抗炎镇痛药之一。继先前的工作之后，当前的研究重点是结合紫外光密度测定法评估不同色谱条件对薄层色谱法灵敏度的影响，即检测和定量布洛芬的浓度范围很广，包括最低浓度。检测限（LOD）和定量限（LOQ）。为此，本文提出了一种可靠且易于使用的LOD和LOQ确定计算程序。此外，准确描述了铭牌和流动相成分分别对这种活性物质的LOD和LOQ的影响。检测结果和在应用色谱条件下获得的布洛芬定量水平证实了硅胶板以及硅胶键合相（即反相（RP）板）在薄层色谱（TLC）中的实用性-布洛芬的低浓度光密度分析，即从几纳克（低于一微克）到几微克/点。在所有测试的色谱系统中，最好的是由硅胶60F组成的系统_254块板与浓缩区（1.05583）和的混合物Ñ正己烷：在比36冰醋酸：：12：乙酸乙酯2（v / v / v），以及RP板，即RP-18 F ₂₅₄铝板用甲醇：水以40:10的体积比（v / v）。这些色谱系统可以定量布洛芬的量为0.229 µg /点和0.228 µg /点，小于1 µg /点。可以说，这项工作中提出的不同色谱系统与224 nm的紫外光密度扫描相结合，可以成功地用于经济有效且灵敏的测定布洛芬作为广泛使用的药物成分以及生活废水中的残留物。已经发现，硅胶的改性以及未改性或改性的硅胶60的层厚度可以影响色谱图的质量以及在正相（NP）和RP系统中布洛芬的检测/定量。因此，为了获得具有预涂层的布洛芬的最佳LOD和LOQ值，需要合适的流动相和色谱板。