Accuracy, precision, and reliability of chemical measurements in natural products research

Abstract

Natural products chemistry is the discipline that lies at the heart of modern pharmacognosy. The field encompasses qualitative and quantitative analytical tools that range from spectroscopy and spectrometry to chromatography. Among other things, modern research on crude botanicals is engaged in the discovery of the phytochemical constituents necessary for therapeutic efficacy, including the synergistic effects of components of complex mixtures in the botanical matrix. In the phytomedicine field, these botanicals and their contained mixtures are considered the active pharmaceutical ingredient (API), and pharmacognosists are increasingly called upon to supplement their molecular discovery work by assisting in the development and utilization of analytical tools for assessing the quality and safety of these products. Unlike single-chemical entity APIs, botanical raw materials and their derived products are highly variable because their chemistry and morphology depend on the genotypic and phenotypic variation, geographical origin and weather exposure, harvesting practices, and processing conditions of the source material. Unless controlled, this inherent variability in the raw material stream can result in inconsistent finished products that are under-potent, over-potent, and/or contaminated. Over the decades, natural products chemists have routinely developed quantitative analytical methods for phytochemicals of interest. Quantitative methods for the determination of product quality bear the weight of regulatory scrutiny. These methods must be accurate, precise, and reproducible. Accordingly, this review discusses the principles of accuracy (relationship between experimental and true value), precision (distribution of data values), and reliability in the quantitation of phytochemicals in natural products.

Revisiting Greek Propolis: Chromatographic Analysis and Antioxidant Activity Study

“…A review publication, pertinent to chemical measurements in natural products research was also regarded [27]. Validation study was performed regarding recovery, linearity, intra-day and inter-day precision.…”

Development of a rapid and simple HPLC-UV method for determination of gallic acid in Schinopsis brasiliensis

“…According Betz et al, the accuracy test through recovery of the matrix is crucial to the development of methodologies for herbal products. The recovery test consists of adding a standard of known concentration after the extraction process in the matrix (Betz et al, 2011).…”

The clinical effectiveness and cost-effectiveness of the PROGENSA® prostate cancer antigen 3 assay and the Prostate Health Index in the diagnosis of prostate cancer: a systematic review and economic evaluation

“…74 l Accuracy is a measure of the closeness of the experimental value to the actual amount of the substance in the matrix. 133 Accuracy often depends on what is used as the true value and whether or not there is a gold standard available. Accuracy is typically assessed by spiked recovery studies in which the amount of a target compound is determined as a percentage of the theoretical amount present in the matrix.…”

“…l Precision measures how close individual measurements of a sample are to each other. 133 Precision is often measured using the CV, which is the SD of the repeated measurement divided by the mean value expressed as a percentage. Precision is subdivided into various components:…”