Manel Alcalà

A review of recent, unconventional applications of ion mobility spectrometry (IMS)

The applications of ion mobility spectrometry (IMS) have grown exponentially beyond its uses for explosive, illicit drug and chemical warfare agent monitoring in recent years. Instrumental developments including new drift tube materials and ionization sources have enabled the manufacturing of more sophisticated and affordable IMS equipment for the advantageous analysis of samples with no pretreatment. The most recent applications of IMS include quality control and cleaning validation procedures in the pharmaceutical industry; determinations of contaminants in food samples; clinical analyses of biological fluids; environmental analyses of contaminants in gaseous, liquid and solid samples; and (bio)process quality control monitoring. Coupling IMS with MS(n) has enabled the analysis of very complex samples and the extraction of knowledge unavailable from isolated MS measurements, especially in the polymer and petroleomic industries.

On-line monitoring of a granulation process by NIR spectroscopy

Near infrared (NIR) spectroscopy has been used in a noninvasively mode to develop qualitative and quantitative methods for the monitoring of a wet granulation process. The formulation contained API (10%w/w) and microcrystalline cellulose and maize starch as main excipients. NIR spectra have been acquired through the glass window of the fluidizer in reflectance mode without causing interference to neither the process nor the formulation. The spectral data has been used to develop a qualitative multivariate model based on principal component analysis (PCA). This qualitative model allows the monitoring of different steps during the granulation process only using the spectral data. Also, a quantitative calibration model based on partial least squares (PLS) methodology has been obtained to predict relevant parameters of the process, such as the moisture content, particle size distribution, and bulk density. The methodology for data acquisition, calibration modeling and method application is relatively low-cost and can be easily performed on most of the pharmaceutical sites. Based on the results, the proposed strategy provides excellent results for the monitoring of granulation processes in the pharmaceutical industry.

Qualitative and quantitative pharmaceutical analysis with a novel hand-held miniature near infrared spectrometer

Although miniaturisation of vibrational spectrometers began approximately a decade ago, only within the last couple of years have real hand-held Raman, infrared and near infrared (NIR) scanning spectrometers became commercially available. On the customer end the development of portable instrumentation was driven by the request for more flexibility of on-site measurements and on the manufacturer side it was supported by the potential and advantages of micro-electromechanical systems (MEMS) production and the implementation of new technologies. With reference to NIR spectroscopy the expectations for a real hand-held system (<100 g) have been recently realised by a pocket-sized spectrometer with a linear variable filter technology (LVF) as monochromator principle and the additional benefit of significantly reduced costs compared to other portable systems. For a real breakthrough and impact of this instrument, however, it had to be demonstrated that competitive analytical results can be achieved. In this respect, the present communication has put to test the performance of this micro-NIR system with reference to selected qualitative and quantitative pharmaceutical applications.

Analysis of low content drug tablets by transmission near infrared spectroscopy: Selection of calibration ranges according to multivariate detection and quantitation limits of PLS models

The content uniformity of low dose products is a major concern in the development of pharmaceutical formulations. Near infrared spectroscopy may be used to support the design and optimization of potent drug manufacturing processes through the analysis of blends and tablets in a relatively short time. A strategy for the selection of concentration ranges in the development of multivariate calibration is presented, evaluating the detection and quantitation limits of the obtained multivariate models. The strategy has been applied to the determination of an active principle in pharmaceutical tablets of low concentration (0-5%, w/w), using Fourier Transform Near Infrared (FT-NIR) transmission spectroscopy. The quantitation and detection limits decreased as the upper concentration level of the calibration models was reduced. The results obtained show that the selection of concentration ranges is a critical aspect during model design. The selection of wide concentration ranges with high levels is not recommended for the determination of analytes at minor levels (<1%, w/w), even when the concentration of interest is within the range of the model.

Determination of drug, excipients and coating distribution in pharmaceutical tablets using NIR-CI

The growing interest of the pharmaceutical industry in Near Infrared-Chemical Imaging (NIR-CI) is a result of its high usefulness for quality control analyses of drugs throughout their production process (particularly of its non-destructive nature and expeditious data acquisition). In this work, the concentration and distribution of the major and minor components of pharmaceutical tablets are determined and the spatial distribution from the internal and external sides has been obtained. In addition, the same NIR-CI allowed the coating thickness and its surface distribution to be quantified. Images were processed to extract the target data and calibration models constructed using the Partial Least Squares (PLS) algorithms. The concentrations of Active Pharmaceutical Ingredient (API) and excipients obtained for uncoated cores were essentially identical to the nominal values of the pharmaceutical formulation. But the predictive ability of the calibration models applied to the coated tablets decreased as the coating thickness increased.

Strategies for constructing the calibration set for a near infrared spectroscopic quantitation method.

Three strategies for the construction of calibration sets have been tried, with the objective to develop and to validate a NIR quantitation method. The first two approaches consist of the use of two types of samples, named: samples of laboratory obtained by mixing the ingredients that compose the drug, and doped samples obtained by under- and over-dosed production samples. In order to improve the prediction results, production samples have been added to each calibration model. The ensuing models were validated with a view to determine their fitness for purpose. However, spectral differences between the laboratory samples and doped samples resulted in spurious predictions in quantifying samples of one type using the model developed from samples of the other. Such differences were studied in depth and a third procedure has been proposed, based on a calibration model constructed with an unique type of sample (laboratory sample) for later to correct it with a few doped samples. This corrected model has a good predictive ability on production samples.

Pharmaceutical gel analysis by NIR spectroscopy. Determination of the active principle and low concentration of preservatives.

Near infrared spectroscopy has proved highly suitable for the analysis of pharmaceutical formulations. However, its limited sensitivity can severely restrict its scope of application. In this work, we determine the active principle and two preservatives in a pharmaceutical preparation available as a hydrogel. The matrix of the pharmaceutical preparation exhibits strong absorption in the NIR spectral region; also, the two preservatives (parabens) are very similar in chemical and spectral terms, and present at low concentrations in the pharmaceutical. These complications make it rather difficult to accurately quantify the active principle and the preservatives, which can only be accomplished by using an effective design in order to prepare the samples to be included in the calibration set and select the optimum spectral range for measuring each analyte. The evaporation of solvents during the measurement process produces increasing errors related with samples air exposition; the introductions of new samples with a wider range of the volatile components correct this effect. An ANOVA of the predictions obtained with the new models shows that correct the error due to evaporation. The proposed method was validated for the analytical control of the studied preparation.

Real-time determination of critical quality attributes using near-infrared spectroscopy: a contribution for Process Analytical Technology (PAT).

Process Analytical Technology (PAT) is playing a central role in current regulations on pharmaceutical production processes. Proper understanding of all operations and variables connecting the raw materials to end products is one of the keys to ensuring quality of the products and continuous improvement in their production. Near infrared spectroscopy (NIRS) has been successfully used to develop faster and non-invasive quantitative methods for real-time predicting critical quality attributes (CQA) of pharmaceutical granulates (API content, pH, moisture, flowability, angle of repose and particle size). NIR spectra have been acquired from the bin blender after granulation process in a non-classified area without the need of sample withdrawal. The methodology used for data acquisition, calibration modelling and method application in this context is relatively inexpensive and can be easily implemented by most pharmaceutical laboratories. For this purpose, Partial Least-Squares (PLS) algorithm was used to calculate multivariate calibration models, that provided acceptable Root Mean Square Error of Predictions (RMSEP) values (RMSEP(API)=1.0 mg/g; RMSEP(pH)=0.1; RMSEP(Moisture)=0.1%; RMSEP(Flowability)=0.6 g/s; RMSEP(Angle of repose)=1.7° and RMSEP(Particle size)=2.5%) that allowed the application for routine analyses of production batches. The proposed method affords quality assessment of end products and the determination of important parameters with a view to understanding production processes used by the pharmaceutical industry. As shown here, the NIRS technique is a highly suitable tool for Process Analytical Technologies.

Quality by design approach of a pharmaceutical gel manufacturing process, part 1: Determination of the design space

This work was conducted in the framework of a quality by design project involving the production of a pharmaceutical gel. Preliminary work included the identification of the quality target product profiles (QTPPs) from historical values for previously manufactured batches, as well as the critical quality attributes for the process (viscosity and pH), which were used to construct a D-optimal experimental design. The experimental design comprised 13 gel batches, three of which were replicates at the domain center intended to assess the reproducibility of the target process. The viscosity and pH models established exhibited very high linearity and negligible lack of fit (LOF). Thus, R(2) was 0.996 for viscosity and 0.975 for pH, and LOF was 0.53 for the former parameter and 0.84 for the latter. The process proved reproducible at the domain center. Water content and temperature were the most influential factors for viscosity, and water content and acid neutralized fraction were the most influential factors for pH. A desirability function was used to find the best compromise to optimize the QTPPs. The body of information was used to identify and define the design space for the process. A model capable of combining the two response variables into a single one was constructed to facilitate monitoring of the process.

Near-Infrared Spectroscopy for the In-Line Characterization of Powder Voiding Part II: Quantification of Enhanced Flow Properties of Surface Modified Active Pharmaceutical Ingredients

In this work, dry-particle coating was used to modify the surface properties of active pharmaceutical ingredients (APIs) having extremely poor flow properties. Near-infrared (NIR) spectroscopy was utilized as a novel approach to characterize the improved flow behavior of APIs and their blends. Acetaminophen and ibuprofen were coated with nano-sized silica at two different coating levels (0.5% and 1% w/w of the API) in dry-particle coating devices viz. magnetically assisted impaction coater (MAIC) and Hybridizer. Surface modified (dry coated) APIs were then blended with excipient (spray dried lactose monohydrate) in a V-blender. As a baseline comparison to dry coating, the silica addition was also accomplished by two commonly used industry methods, i.e., passing a portion of API with silica through a sieve (sieve blending method) or blending a portion of API powder with silica in a V-blender (preblending method). Flow results showed that dry particle coated acetaminophen as well as ibuprofen blends performed significantly better than uncoated API blends at higher API concentrations. In addition, examination of the flow intensity from NIR spectra (inverse signal to noise ratio of spectra) and its standard deviation revealed that dry particle coated blends showed better uniformity of flow as compared to the other methods. Angle of repose measurements corroborated these results, showing that the majority of the blends prepared from coated APIs stayed in either passable or fair category.