Machine learning and deep learning for diagnosis of Polyendocrine Metabolic Ovarian Syndrome: systematic review and meta-analysis.

Liquid chromatography—including thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC/LC)—and gas chromatography (GC) are fundamental separation techniques in analytical chemistry, used for the separation, identification, and quantification of individual components in a mixture across a wide range of applications, from biochemistry, pharmaceutical, food, and environmental research to forensic analysis [,,,,]. The combination of chromatography and mass spectrometry (MS) represents the “gold standard” in modern analytical chemistry. Together, these techniques allow for the identification and quantification of substances at extremely low concentrations, even in very complex mixtures such as biological or food samples [,,,,,,]. The graphs in show the progression of published works on the applications of chromatographic methods in food and drug analysis during the first quarter of the new millennium. Based on these data, it can be said that chromatography and spectrometry are completely universal analytical techniques and extremely useful tools that are applicable in food, pharmaceutical, and environmental analysis, and capable of analyzing both simple and complex samples/matrices, as shown in . In the food industry, chromatographic systems/techniques are applied to consumer protection and quality assurance. Highly sensitive methods such as liquid chromatography–tandem mass spectrometry (LC-MS/MS) allow for contaminant analysis and residue monitoring, i.e., the detection of hundreds of different pesticides and other agrochemicals in a single sample of fruit, vegetables, and other foods, even trace amounts below the limits set by legislation, or the detection of mycotoxins, heavy metals, or other substances migrating from packaging materials (e.g., phthalates) [,,,,,,,,,]. It is important to mention that chromatography also helps to verify the authenticity of food and detect its adulteration, for example, the dilution of olive oil, the addition of synthetic sweeteners to honey, or the substitution of a declared type of meat or fish [,,,]. Pharmaceutical analysis is a field of study concerned with the qualitative and quantitative (identification, purity determination) evaluation of active pharmaceutical ingredients (APIs), excipients, and final dosage forms [,,]. This field can be understood as part of medicinal (pharmaceutical) chemistry or as a specific application of analytical chemistry. In any case, separation methods—specifically, chromatography with MS detection—have become an essential part of the process for ensuring the safety and efficacy of drugs in pharmaceutical development and manufacturing [,,,,,]. In addition, LC-MS/MS is commonly used in bioanalysis to monitor drug (and their metabolites) levels in the blood or tissues of patients during clinical trials and for proper treatment adjustment. Chromatographic methods are also used to monitor how a drug substance degrades over time due to temperature, humidity, or light, which directly determines the expiration date on the drug packaging [,,,]. In this context, it is worth mentioning the presence of LC-MS/MS methods among “omics” techniques [,,,,,,,] and the use of chromatographic methods in the fight against counterfeit medicines, as they allow us not only to determine whether a medicine contains the declared active substance, but also in what quantity and whether or not it contains dangerous additives or impurities [,].