Development of quantitative HPTLC methods for dolutegravir, lamivudine, and tenofovir disproxil fumarate in a combination pharmaceutical product using a model process published earlier for transfer of minilab TLC screening methods to HPTLC-densitometry

High-performance thin-layer chromatography (HPLTC)–densitometry methods are described for the analysis of the anti(retro)virals dolutegravir (D), lamivudine (L), and tenofovir disoproxil fumarate (TDF) in a pharmaceutical tablet product. To the best of our knowledge, no previous quantitative planar chromatography method has been reported in the literature for this combination formulation. The method for L was transferred from a thin-layer chromatography (TLC) screening method published in the Global Pharma Health Fund (GPHF) Minilab Manual designed for identification of counterfeit and substandard drug products using a model process published earlier. D and TDF are not included in the list of drugs for which TLC screening methods are published for the Minilab, but HPTLC–densitometry procedures were developed for them using the transfer process guidelines. L was analyzed simultaneously with TDF on Merck Premium Purity silica gel 60 F plates using the mobile phase ethyl acetate–methanol–acetone–concentrated ammonium hydroxide (30:7:3:1) and densitometric scanning at 254 nm. D was analyzed on a second plate by scanning at 366 nm after chromatography with the chloroform–methanol–formic acid (32:8:2) mobile phase. Data for all three drugs are shown to meet the requirements of the model transfer process for calibration curve r values, assay of tablets relative to their label values, peak purity/peak identity tests, and validation by standard addition analysis of samples spiked at 50%, 100%, and 150% of the label value of active ingredients. A TLC screening method for TDF in the combination product was developed and published online with open access.

Practical Screening Procedure for Sulfathiazole in Honey

A simple, inexpensive procedure is described for rapidly screening small samples of honey for sulfathiazole (ST), a drug formerly used but not approved in the United States for the prophylactic treatment of American foulbrood disease of bees. The method uses 2 plastic tubes arranged in tandem. The upper tube contains a bed of alumina, which removes some interfering pigments. The lower tube contains a very small bed of anion exchange resin in the HSO4- form, which traps the ST. The drug is eventually eluted and detected using the Bratton-Marshall diazotization-coupling reagents. Honey containing 0.1 ppm ST can be readily detected. An optional dye concentration step permits the detection of as little as 25 ppb ST.

Recent Advances in Thin-Layer Chromatography of Pesticides

Advances in the use of thin-layer chromatography (TLC) and high-performance TLC (HPTLC) for separation, detection, and qualitative and quantitative determination of pesticides, other agrochemicals, and related compounds are reviewed for the period 1996–1998. Analyses are covered for avariety of food, biological, and environmental samples and for residues of various pesticides, including insecticides, herbicides, and fungicides, belonging to different chemical classes. References on formulation analysis, hydrophobicity studies, and use of TLC and thin-layer radiochromatography for studies of pesticide metabolism, degradation, uptake, and related studies also are included.

Review of HPTLC in Drug Analysis: 1996-2009

Analytical methods for drug substances, formulations, and clinical samples developed and validated on HPTLC plates during the period 19962009 are reviewed. Procedures, materials, and instrumentation for the different steps in the HPTLC procedure and validation of results; applications to bulk drugs, formulations, stability studies, biological samples (e.g., urine and plasma), and hydrophobicity studies; and prospects for the use of HPTLC for drug analysis in the future are described.

Biennial Review of Planar Chromatography: 2009–2011

The most important advances in the planar chromatography published between November 1, 2009 and November 1, 2011 are reviewed in this paper. Included are an introduction to the current status of the field; history, student experiments, books, and reviews; theory and fundamental studies; apparatus and techniques for sample preparation and TLC separations (sample application and plate development with the mobile phase); detection and identification of separated zones (chemical and biological detection, TLC/MS, and TLC coupled with other methods); techniques and instruments for quantitative analysis; preparative layer chromatography; and thin layer radiochromatography. Selected applications are given in the various sections of the review, especially for modern HPTLC-densitometry.

Development and Validation of a Method for Determination of Caffeine in Diuretic Tablets and Capsules by High-Performance Thin-Layer Chromatography on Silica Gel Plates with a Concentration Zone Using Manual Spotting and Ultraviolet Absorption Densitometry

A new quantitative method using silica gel high-performance thin-layer chromatography plates with channels and a concentration zone, manual application of standards and samples, development with methanol–ethyl acetate (15 + 85) mobile phase, and ultraviolet absorption densitometry is reported for the determination of caffeine in diuretic pharmaceutical preparations. Tablet and capsule products containing potassium salicylate, acetaminophen, and salicylamide as active ingredients were analyzed to test the applicability of the new method, and precision, accuracy, linearity, limits of detection and quantitation, and selectivity were validated. The milligrams of caffeine in each tablet ranged from 48.0 to 51.0, and the milligrams in each capsule from 37.9 to 40.3. Within-day precision was 1.48 and 1.78% (n = 6), and interday precision 0.723 and 1.26% (n = 5) for analysis of 2 tablets and 2 capsules, respectively. Accuracy validation of the tablet and capsule results produced errors of 1.0 and 1.9% for spiked blank analyses and 2.6 and 3.5% for standard addition analyses, respectively. A comparative study using a caffeine standard solution and a multicomponent analgesic tablet solution containing caffeine, acetaminophen, and acetylsalicylic acid showed that manual application on the concentration zone, instrumental application on the concentration zone, and instrumental application on the silica gel gave quite similar results in terms of number of theoretical plates, resolution, limit of detection, and linearity.

High-Performance Liquid Chromatography/Mass Spectrometry Analysis of Botanical Medicines and Dietary Supplements: A Review

This article reviews research on the qualitative and quantitative analysis by high-performance column liquid chromatography/mass spectrometry (LC/MS) and LC/tandem mass spectrometry (LC/MS/MS) of botanical drugs, drug substances or preparations, and finished botanical products. In addition, LC/MS and LC/MS/MS techniques and commercial instruments are described and compared briefly, and prospects for future use of these methods for the analysis of botanicals are suggested. Some applications of direct MS without LC are also described.

Recent Advances in the Thin-Layer Chromatography of Pesticides: A Review

Advances in the applications of thin-layer chroma-tography (TLC) and high-performance TLC for the separation, detection, identification, and determination of pesticides, other agrochemicals, and related compounds are reviewed for the period 2000–2002. Analyses are described for a variety of samples, such as food, biological, and environmental samples, and for residues of pesticides of various types, including insecticides, herbicides, and fungicides, belonging to different chemical classes. References are included for residue analysis, hydrophobicity studies, and the use of TLC and thin-layer radiochromatography for studies of pesticide metabolism, degradation, uptake, and related topics.

Pesticide Residue Analysis (1999–2000): A Review

The literature of pesticide residue analysis is reviewed selectively for the period 1999–2000. Analyses of a wide range of pesticide classes and sample types, as well as some related organic pollutants, are covered. Studies of exposure and monitoring as well as pesticide degradation, persistance, leaching, mobility, and metabolism studies are included.

Recent Advances in Thin-Layer Chromatography of Pesticides

Advances in the applications of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) for the separation, detection, and qualitative and quantitative determination of pesticides, other agrochemicals, and related compounds are reviewed for the period 1998–2000. Analyses are covered for a variety of samples, such as food, biological, and environmental, and for residues of pesticides of various types, including insecticides, herbicides, and fungicides, belonging to different chemical classes. References on formulation analysis, hydrophobicity studies, and the use of TLC and thin-layer radiochromatography (TLRC) for studies of pesticide metabolism, degradation, uptake, and related studies are also included.

Using High Performance Thin Layer Chromatography-Densitometry to Study the Influence of the Prion [RNQ+] and Its Determinant Prion Protein Rnq1 on Yeast Lipid Profiles

The baker's yeast Saccharomyces cerevisiae harbors multiple prions that allow for the creation of heterogeneity within otherwise clonal cell populations. However, in many cases, the consequences of prion infection are entirely unclear. Predictions of prion-induced changes in cell physiology are complicated by pleotropic effects, and detection is often limited to relatively insensitive cell growth assays that may obscure many physiological changes. We previously showed that silica gel high performance thin-layer chromatography-densitometry (HPTLC) can be used to empirically determine prion-induced changes in lipid content in yeast. Here, we conduct pair-wise quantifications of the relative levels of free sterols, free fatty acids, and triacylglycerols [petroleum ether-diethyl ether-glacial acetic acid (80:20:1, v/v/v) mobile phase and phosphomolybdic acid (PMA) detection reagent]; steryl esters, methyl esters, and squalene [hexane-petroleum ether-diethyl ether-glacial acetic acid (50:20:5:1, v/v/v/v) and PMA]; and phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol (chloroform-diethyl ether-acetic acid (65:25:4.5, v/v/v) and cupric sulfate-phosphoric acid) in otherwise clonal prion-infected ([RNQ+]) and prion-free ([rnq-]) cells in both stationary- and logarithmic-growth phases. We detected multiple statistically significant differences between prion-infected and prion-free cells that varied by growth phase, confirming our pr evious observations that prions exert distinct influences on cell physiology between stationary- and log-phase growth. We also found significant differences between cells expressing or lacking the Rnq1 protein which forms the [RNQ+] prion, providing new clues to the as yet unresolved normal biological function of this prion-forming protein. This investigation further emphasizes the utility of HPTLC-densitometry to empirically determine the effects of prions and other presumed innocuous gene deletions on lipid content in yeast, and we expect that additional analyses will continue to resolve the physiological effects of prion infection.

Biennial Review of Planar Chromatography: 2013-2015

The most important advances in planar chromatography published between November 1, 2013 and November 1, 2015 are reviewed in this paper. Included are an introduction to the current status of the field; student experiments, books, and reviews; apparatus and techniques for sample preparation and TLC separations; detection and identification of separated zones; quantitative analysis; preparative layer chromatography; and thin layer radiochromatography. Selected applications are given in the various sections of the review.