A new approach based on inversion of a partial least squares model searching for a preset analytical target profile. Application to the determination of five bisphenols by liquid chromatography with diode array detector

A brief review on application of design of experiment for the analysis of pharmaceuticals using HPLC

The quality pioneer Dr. Joseph M. Juran first proposed the idea of quality by design. According to him, pharmaceutical quality by design is an organised approach to product development that starts with predetermined goals and places an emphasis on product, process understanding, control based on reliable science and quality risk management. The quality of a product or process can typically be affected by a number of input elements. Design of experiments has been employed widely recently to understand the impacts of multidimensional and interactions of input parameters on the output responses of analytical procedures and pharmaceutical goods. Depending on the design of experiments objectives, screening, characterization, or optimization of the process and formulation, a variety of designs, such as factorial or mixture, can be used. The most popular designs used in the stage of screening or factor selection are the 2-Level Factorial and Plackett-Burman designs, both of which have two levels for each factor (k), both economical and effective, and in optimization widely used designs in this step are full factorial at three levels, central composite, Box-Behnken design. The analysis of variance, regression significance, and lack of fit of the regression model were some of the key topics covered in the discussion of the main components of multiple regression model adjustment. Design of experiments is thus the primary element of the formulation and analytical quality by design. The details about design of experiments used for the analysis of pharmaceutical formulation using HPLC.

Model inversion and three-way decompositions in the analytical quality by design strategy for the determination of phthalates BY HS-SPME-GC-MS

In this work, strategies within Analytical Quality by Design (AQbD) with tools of the Process Analytical Technology (PAT) were used in the development of a head space-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) procedure for the multiresidue analysis of four phthalic acid esters, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, dibutyl phthalate and diethyl phthalate (regulated by Commission Regulation (EU) No 10/2011). The approach is based on the fact that the intended quality of the resulting chromatograms is defined in terms of the loadings on the sample mode of a Parallel Factor Analysis (PARAFAC2) decomposition. These loadings are the ones used for the inversion of a Partial Least Squares (PLS2) prediction model that has been previously fitted. The inversion gives the experimental conditions that represent a compromise solution in terms of the desired or target values of the responses (Critical Quality Attributes, CQAs), while guaranteeing that these experimental conditions are inside the experimental domain of the Control Method Parameters (CMPs). This strategy results in experimental conditions of extraction time and temperature that lead to a chromatogram of predefined quality for the four analytes together, with the subsquent saving of time and energy. The experimental conditions achieved have been experimentally verified and figures of merit of the analytical method have been determined. The method has been applied to a case study, bottled natural and flavoured mineral water. Concentrations around 0.3 μg L-1 of dibutyl phthalate have been found in 5 of the 22 bottles of water analysed.

The inversion of multiresponse partial least squares models, a useful tool to improve analytical methods in the framework of analytical quality by design

Analytical Quality by Design (AQbD) is the adaptation of Quality by Design (QbD) when it is applied to the development of an analytical method. The main idea is to develop the analytical method in such a way that the desired quality of the Critical Quality Attributes (CQAs), stated via the analytical target profile (ATP), is maintained while allowing some variation in the Control Method Parameters (CMPs). The paper presents a general procedure for selecting factor levels in the CMPs to achieve the desired responses, characterized by the CQAs, when liquid chromatographic methods are to be used for the simultaneous determination of several analytes. In such a case, the CMPs are usually the composition of the ternary mobile phase, its flow rate, column temperature, etc., while typical CQAs refer to the quality of the chromatograms in terms of the resolution between each pair of consecutive peaks, initial and final chromatographic time, etc. The analytical target profile in turn defines the desired characteristics for the CQAs, the reason for the whole approach. The procedure consists of four steps. The first is to construct a D-optimal combined design (mixture-process design) to select the domain and levels of the CMPs. The second step is to fit a PLS2 model to predict the analytical responses expressed in the ATP (the good characteristics of the chromatogram) as a function of the CMPs. The third step is the inversion of the PLS2 model to obtain the conditions necessary to obtain the preset ATP in the corresponding CQAs. The inversion is performed computationally in order to estimate the Pareto front of these responses, namely, a set of experimental conditions to perform the chromatographic determination for which the desired critical quality attributes are met. The fourth final step is to obtain the Method Operable Design Region (MODR), that is, the region where the CMPs can vary while maintaining the quality of the CQAs. The procedure has been applied to some cases involving different analytes, all of which are regulated by the European Union due to their toxicity to human health, namely five bisphenols and ten polycyclic aromatic hydrocarbons.

New Healthy Low-Sugar and Carotenoid-Enriched/High-Antioxidant Beverage: Study of Optimization and Physicochemical Properties

Lutein is a prominent biologically active carotenoid pigment with a polyene skeleton that has great benefits for human health. The study examined the synergistic effects of potentially functional components, including lutein carotenoid (LC), Mentha × Piperita extract (MPE), and Citrus × aurantifolia essential oil (CAEO), all three as bioactive components and antioxidants (AOs), on the physicochemical characteristics of a new low-sugar and carotenoid-enriched high-antioxidant beverage. Sucralose was utilized as a non-nutritive sweetener. Polynomial equations obtained by combined design methodology (CDM) were fitted to the experimental data of total phenolic and flavonoid contents (TPC and TFC, respectively) and antioxidant potential of the beverages using multiple regression analysis with R2 (determination coefficient) values of 0.87, 0.89, and 0.97, respectively. Estimated response values for the TPC, TFC, and antioxidant potential (determined as 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH•) scavenging activity) of the optimum beverage formulation were 41.90 mg gallic acid equivalent (GAE) per L-1, 27.51 mg quercetin equivalent (QE) per L-1, and 34.06%, respectively, with a desirability value of 0.74. The potentially functional components had a synergistic effect on the antioxidant potential. This healthy beverage can have the potential to enhance health benefits and may have therapeutic potential for diabetic patients.

Application of the "Method Operable Design Region" (MODR) approach for the development of a UHPLC method for the assay and purity determination of risperidone in risperidone drug substance and other formulations

To understand the role of analytics in drug development, regulatory bodies also started using the approach of Quality by Design (QbD) during analytical method developments. The present study deals with the development of the "Method Operable Design Region" for assay and purity determination of risperidone in risperidone drug substance and formulations usingy UHPLC. Five different column chemistries, five different pH buffers, oven temperatures from 25 to 45°C, and different organic modifier composition, column lengths and flow rates were studied and statistically evaluated using Fusion QbD software. The final method parameters were selected by performing multivariable changes in a single run and evaluated using the Monte Carlo simulation approach. The uniqueness of this method is that it is mass compatible, a total of 10 peaks are separated within a short run time of 12.0 min and it uses a "Platforming approach", which means the use of a single method for testing the drug substance, different strengths of a drug product and different formulations. The same method can be also used for the determination of the preservative (benzoic acid) in risperidone 1 mg/ml oral solution. The use of the QbD approach is aligned with the US Pharmacopeia <1220>, BP supplementary chapter 2022 and the International Conference on Harmonization Q14 guidelines for life cycle management of analytical methods.

Procedure to explore a ternary mixture diagram to find the appropriate gradient profile in liquid chromatography with fluorescence detector. Application to determine four primary aromatic amines in napkins

The purpose of this work is to develop a tool to search for a gradient profile with ternary or binary mixtures in liquid chromatography, that can provide well-resolved chromatograms in the shortest time for multianalyte analysis. This approach is based exclusively on experimental data and does not require a retention time model of the compounds to be separated. The methodology has been applied for the quantification of four primary aromatic amines (PAAs) using HPLC with fluorescence detector (FLD). Aniline (ANL), 2,4-diaminotoluene (TDA), 4,4'-methylenedianiline (MDA) and 2-aminobiphenyl (ABP) have been selected since their importance in food contact materials (FCM). In order to achieve that, partial least squares (PLS) models have been fitted to relate CMP (control method parameters) and CQA (critical quality attributes). Specifically, PLS models have been fitted using 30 experiments for each one of the four CQA (resolution between peaks and total elution time), considering 33 predictor variables (the composition of the methanol and acetonitrile in the mobile phase and the time of each one of the 11 isocratic segments of the gradient). These models have been used to predict new candidate gradients, and then, some of those predictions (the ones with resolutions above 1.5, in absolute value, and final time lower than 20 min) have been experimentally validated. Detection capability of the method has been evaluated obtaining 1.8, 189.4, 28.8 and 3.0 µg L^-1 for ANL, TDA, MDA and ABP, respectively. Finally, the application of chemometric tools like PARAFAC2 allowed the accurate quantification of ANL, TDA, MDA and ABP in paper napkins in the presence of other interfering substances coextracted in the sample preparation process. ANL has been detected in the three napkins analysed in quantities between 33.5 and 619.3 µg L^-1, while TDA is present in only two napkins in quantities between 725.9 and 1908 µg L^-1. In every case, the amount of PAAs found, exceeded the migration limits established in European regulations.

Method operable design region obtained with a partial least squares model inversion in the determination of ten polycyclic aromatic hydrocarbons by liquid chromatography with fluorescence detection

A chromatographic method with the Analytical Quality by Design (AQbD) methodology is developed for the simultaneous determination by HPLC-FLD of ten PAHs (naphthalene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, perylene, benzo[b]fluoranthene, and benzo[a]pyrene), widely spread in the environment. The construction of the Method Operable Design Region (MODR) is conducted, for the first time, via the inversion of a multiresponse Partial Least Squares (PLS2) model, which is needed to maintain the correlations among the Critical Method Parameters (CMP), among the Critical Quality Attributes (CQA), and the covariance between one another. The five CMP considered were the composition of the mobile phase (water, methanol, acetonitrile), flow rate, and column temperature. The eight CQA were linked to resolution between peaks recorded in the same emission wavelength (greater than 1.4) and the total time (less than 15 minutes). By systematic use of experimental design and parallel coordinates plots to explore the Pareto optimal front obtained with the PLS2 model inversion, the computed MODR is formed by convex combinations of eight specific settings of Critical Method Parameters that have a mobile phase with percentages of water between 37 and 38 %, of methanol from 13 and 22 %, and of acetonitrile between 41 and 49 %, together with a flow rate between 1.47 and 1.50 mL min^-1, and column temperature between 41.9 and 44.0 °C in their adequate combinations. All the chromatographic peaks are well resolved, with total time varying between 12.96 and 15.66 min inside the estimated MODR and the analytical method is accurate with CCβ between 0.9 and 7.0 µg L^-1 with probability of both false positive and false negative equal to 0.05.

Chromatographic Applications in the Multi-Way Calibration Field

In this review, recent advances and applications using multi-way calibration protocols based on the processing of multi-dimensional chromatographic data are discussed. We first describe the various modes in which multi-way chromatographic data sets can be generated, including some important characteristics that should be taken into account for the selection of an adequate data processing model. We then discuss the different manners in which the collected instrumental data can be arranged, and the most usually applied models and algorithms for the decomposition of the data arrays. The latter activity leads to the estimation of surrogate variables (scores), useful for analyte quantitation in the presence of uncalibrated interferences, achieving the second-order advantage. Recent experimental reports based on multi-way liquid and gas chromatographic data are then reviewed. Finally, analytical figures of merit that should always accompany quantitative calibration reports are described.

Simultaneous determination of 9 environmental pollutants including bisphenol A in vegetable oil by solid phase extraction-liquid chromatography-tandem mass spectrometry

In this study, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method with solid phase extraction was established for the simultaneous determination of bisphenol A, bisphenol F, bisphenol S, 4-nonylphenol, n-nonylphenol, octylphenol, n-octylphenol, perfluorooctane sulfonate acid and perfluorooctanoic acid in vegetable oil. The sample was extracted with ammonia acetonitrile solution (1 : 9, V/V) by ultrasonication. And the obtained extract was purified by using a PRIME HLB solid phase extraction column. The identification and quantification of the compounds was performed by liquid chromatography-tandem mass spectrometry in multiple reaction monitoring (MRM) mode. The internal standard method was used for quantitative analysis. Under optimal experimental conditions, the limits of quantitation of bisphenol A, bisphenol F, bisphenol S, 4-nonylphenol, n-nonylphenol, octylphenol and n-octylphenol in vegetable oil were 1.0 μg kg-1. The limits of quantitation of perfluorooctane sulfonic acid and perfluorooctanoic acid in vegetable oil were 0.1 μg kg-1. The average spiked recoveries of the method were in the range of 89.2-117.1% with the relative standard deviations (RSD) of 2.9-9.8% (n = 6). This method is sensitive, versatile and reproducible, and is suitable for the simultaneous determination of bisphenol A, bisphenol F, bisphenol S, 4-nonylphenol, n-nonylphenol, octylphenol, n-octylphenol, perfluorooctane sulfonate acid and perfluorooctanoic acid in vegetable oil.