Process Analytical Technology Tool Research Articles

Calibration transfer of near infrared spectrometers for the assessment of plasma ethanol precipitation process

Plasma ethanol precipitation process is an important step in the biopharmacy production process, and near infrared spectroscopy (NIRS) is an effective process analytical technology (PAT) tool in detecting the key quality attribute: the total protein (TP) content. But establishing a robust model is pretty complex. The aim of this study was to explore the calibration transfer strategy between master and slave spectrometers with the biopharmacy. Firstly, 8 batches of ethanol precipitation process were experimented. The changing spectra were collected by two spectrometers, reference values were measured by biuret method. Then, calibration transfer based on the PRS algorithm was carried out. Finally, before establishment of the optimal TP content partial least squares regression (PLSR) model of calibration transfer, rank sample set partitioning based on joint x-y distance (Rank-SPXY) and spectral pretreatment methods were selected after comparison. The determination coefficients of prediction (Rp2) and root mean squares error of prediction (RMSEP) were 0.934 and 0.8395 g/L, respectively. The results showed that Rank-SPXY-PRS was an effective calibration transfer strategy with different NIRS spectrometers. To some extent, the predictive capability of PLSR model was improved after calibration transfer, and it could provide reference for the further research in biopharmacy production process.

Induced nucleation by gassing and its monitoring for the design and operation of an MSMPR cascade

Control of the nucleation step – the first and most important step in the crystallization process – is crucial for obtaining a desired crystalline product with defined properties such as shape, size and size distribution.For batch crystallization, much effort has been made to identify and investigate the various parameters that affect the conditions under which nucleation takes place. In this context, a promising approach to control the events at the beginning of crystallization can be seen in the use of bottled pure synthetic air to induce nucleation. This process is called gassing crystallization. In this paper, for the first time gassing with synthetic air was applied to induce nucleation in a continuously operated single-stage MSMPR crystallizer. To determine the operating boundaries of an MSMPR cascade and to monitor the process, a self-constructed conductivity probe was used, which represents an inexpensive process analytical technology tool. The experimental results for the binary model system l-alanine/water demonstrate that gassing shows a great potential to carry out the nucleation step in a controlled manner, thus enabling the production of crystals with a constant product quality.

Printing pharmaceuticals by inkjet technology: Proof of concept for stand-alone and continuous in-line printing on orodispersible films

Orodispersible films (ODFs) are promising dosage forms for special patient populations like paediatrics or elderly persons. By printing active pharmaceutical ingredients (APIs) onto orodispersible films, the flexibility of drug dosing is increased and therefore provides potential for personalized medicines. Until now, only small-scale experiments have been conducted, where continuous jetting was performed,but no continuous ODF production was realized. This study deals with the technology transfer from a small-scale inkjet printing system to a pilotscale process by incorporating the same print head assembly into a continuous ODF production process. ODFs made from hydroxypropylcellulose were non-continuously printed multiple times with test ink containing a blue colorant as model drug and were compared to continuously printed ODFs. To identify optimal manufacturing conditions, parameter settings like firing frequencies, resolution, voltage, etc. were varied and these effects were analysed by UV–Vis spectroscopy, image analysis and light microscopy. During continuous production, a linear correlation between firing frequency (100 to 600 Hz) and deposited colourant content could be observed (R = 0.999) as well as for the applied voltage (90–110 V) and the ink content (R = 0.998). A minor impact of the distance between the print head and the substrate was observed. By increasing the natural resolution (50 dpi) of the print head, the deposited ink amount could be doubled. A transfer from the non-continuous production (1 layer of 1 cm × 2 cm with a resolution of 750 dpi × 750 dpi) to the continuous production (corresponding to 380 Hz firing frequency on 6 cm2 ODF) was successfully performed. Furthermore, image analysis was proven as useful tool for process analytical technology (PAT) of the continuously printed ODFs. The continuous ODF production with direct printing enabled various printing concepts, which may serve for individualized dosing in personalized medicine treatment in the near future.

Development and Evaluation of Process Analytical Technology (PAT) Tool For Functional Coating Weight Gain Determination By Pellet Characteristics Measurement

Development and Evaluation of Process Analytical Technology (PAT) Tool For Functional Coating Weight Gain Determination By Pellet Characteristics Measurement

Determination of reaction parameters in methanol to gasoline (MTG) process using infrared spectroscopy and chemometrics

Abstract Determination and monitoring of the reaction parameters such as “methanol conversion” and “products selectivity” in methanol to gasoline process is an essential part. Determination of these parameters are usually performed by gas chromatography or other chromatographic based methods which are considered as expensive and time consuming routes. A method for rapid and cheap determination of methanol conversion and product selectivity to aromatics and iso-paraffins in methanol to gasoline process as a route for clean gasoline production was proposed. The method can be performed off-line, on-line or at-line as a process analytical technology tool. The method consists of obtaining near infrared and mid infrared spectra from organic and aqueous fractions of methanol to gasoline reactor during the reaction. The spectroscopic data were treated using least squares support vector machine algorithm and product selectivity -to aromatics and iso-paraffins- and methanol conversion parameters were modelled. The least squares support vector machine results were obtained using radial basis function and parameter optimization was performed using the simplex method. The gas-chromatography method was used as the reference method. The root mean squared error of prediction values were 2.7 (v/v%) for aromatics, 1.4 (v/v%) for iso-paraffins and 1.5 (w/w%) for methanol conversion parameters. The proposed method compared to the existing chromatographic based techniques can provide a cleaner, faster and cheaper route with good accuracy for measurement of this catalytic reaction parameters.

Transient Temperature Monitoring of Pharmaceutical Tablets During Compaction Using Infrared Thermography.

Manufacturing of pharmaceutical tablets from powders is always accompanied by the conversion of irreversible mechanical work of compaction into heat. The heat is generated due to friction between powder particles, particles and the die wall, plastic deformation of particles, bonding, and other irreversible processes. The resulting temperature increase potentially might have significant effects on a tablet's mechanical properties, disintegration time, and drug release. In the present work, we show that using infrared thermography as a nondestructive and noncontact process analytical technology (PAT) tool to measure the tablet's rate of cooling, in contrast to the temperature evolution, can be directly related to the tablet's thermal diffusivity. Results show the potential capabilities of this technique to discriminate and toward predicting tensile strength of tablets between same formulations produced at same compaction force but experienced different process shear conditions. Correlation of the tablet's tensile strength, relative density, and rate of cooling at regular regime with respect to different process shear is also discussed.

Continuous end-to-end production of solid drug dosage forms: Coupling flow synthesis and formulation by electrospinning

Based on the concept of continuous manufacturing an end-to-end benchtop device was developed unprecedented for the production of solid drug dosage forms by connecting flow synthesis and formulation via electrospinning (ES). Together with the optimized two-step continuous-flow synthesis of acetylsalicylic acid (ASA) a water-soluble polymeric excipient (polyvinylpyrrolidone K30, PVPK30) was introduced. The resulting polymeric solution could be readily electrospun into solid nanofibers with high purity in one single step due to the excellent yet gentle drying effect of ES. The ASA-loaded fibers were electrostatically deposited onto a water-soluble pullulan sheet and the obtained double-layered films were continuously cut into orally dissolving webs (ODWs) as final dosage formulation. The synthesis as well as the dosing of the fibrous films were monitored by Process Analytical Technology (PAT) tools (IR and Raman spectroscopy) with active feedback on product quality. The successful coupling of flow synthesis and fiber formation confirms that ES enables versatile formulation of pharmaceuticals in future continuous production systems.

Additive manufacturing of prototype elements with process interfaces for continuously operating manufacturing lines

Rapid prototyping based on in silico design and 3D printing enables fast customization of complex geometries to multiple needs. This study utilizes, additive manufacturing for rapid prototyping of elements for continuously operating mixing geometries including interfaces with process analytical technology (PAT) tools, to show that 3D printing can be used for prototyping of both parts of production line and PAT interfacing solution. An additional setup was designed for measuring the dynamic calibration samples for a semi-quantitative near infrared (NIR) spectroscopic model. The powder was filled in a small calibration chamber and in-line NIR spectra of calibration samples were collected from moving material while mimicking the powder flow dynamics in a typical continuous mixer. This dynamic powder mixing system was compared with a static powder calibration model where the NIR probe was placed at different positions on a static sample. Principal component analysis (PCA) revealed that the 3D printed device with dynamic measurement of the NIR spectra had more potential for quantitative analysis. With the prototype continuous mixer, two differently placed process interfaces for NIR spectroscopic monitoring of the powder mixing were evaluated. With this approach, the importance of positioning the process analytical tools to assess the blend uniformity could be demonstrated. It was also observed that with the longer mixing geometry, a better mixing result was achieved due to a larger hold up volume and increased residence time.

Quality Assurance of Model Infant Milk Formula Using a Front-Face Fluorescence Process Analytical Tool

Front-face fluorescence spectroscopy (FFFS) was evaluated as a quality assurance process analytical technology (PAT) tool for infant milk formula (IMF) manufacture. Batches of first-stage IMF (60:40 whey protein:casein ratio) powder were produced with protein:fat:lactose ratios of 1.3:3.6:7.3, differing only in heat treatment applied prior to spray drying (72, 95, or 115 °C for 15 s). Each IMF powder was stored at 15 ± 2 °C and 37 ± 2 °C and analyzed at months 0, 3, 6, and 12. Partial least squares (PLS) models were developed for IMF in both powder and liquid states using FFFS spectra to predict pre-drying heat treatment temperature, soluble protein content, and storage time. Models developed using tryptophan emission spectra for IMF powder predicted storage time, pre-drying heat treatment temperature, and soluble protein content with RMSECV values of 0.3 months, 8.3 °C, and 1.01 g protein/100 g powder, respectively. IMF powders were rehydrated to 13% total solids and analyzed using the vitamin A emission spectra. Models developed for rehydrated IMF predicted storage time and pre-drying heat treatment temperature with RMSECV values of 1.5 months and 6.7 °C, respectively. Surface free fats were predicted with an RMSECV range of 0.12–0.20% (w/w of powder) in rehydrated IMF. PLS discriminant analysis models developed for both powder and liquid IMF samples successfully discriminated for storage temperature. This preliminary study demonstrates the strong potential of FFFS as a PAT tool for IMF quality assurance.

Process analytical technology for cheese manufacture

SummaryRecent research on the development and application of process analytical technology (PAT) for cheese manufacture is reviewed in this article. PAT is a framework for innovative process manufacturing and quality assurance, which has been widely investigated for dairy processing applications, where particular processing challenges arise due to the variations in the physiochemical properties of milk. Cheese manufacturers are increasingly considering the adoption of a PAT approach to facilitate manufacture of cheese with enhanced product quality, safety and process efficiency. However, to date adoption of PAT in the dairy industry has been limited due to challenges associated with development and validation of calibration models, instrument variability, sanitary design and compatibility with processing environments. New technical developments in PAT tools, advances in chemometric modelling, robust data management tools and improved understanding of critical product and process parameters will facilitate further adoption of a PAT approach in cheese manufacture.

Effect of Technically Relevant X-Ray Doses on the Structure and Function of Alcohol Dehydrogenase and Hen Egg-White Lysozyme.

The effect of different irradiation doses on the structure and activity of lyophilized powders of Hen Egg-White Lysozyme (HEWL) and alcohol dehydrogenase (ADH) was investigated using these substances as models for robust and sensitive proteins, respectively. Three doses were selected to cover the ranges of radio-sterilization (25kGy), treatment of blood products (25Gy) and annual background radiation dose (approximately 2mGy). The results offer an initial screening of different irradiation doses and support the development of X-ray imaging methods as non-destructive process analytical technology (PAT) tools for detecting the visible particulate matters in such products. HEWL and ADH were exposed to X-rays in the solid state. The effect of irradiation was determined directly after irradiation and after storage. Structural changes and degradation were investigated using SAXS, SDS-PAGE and HPLC-MS. Protein functionality was assessed via activity assays. Lower irradiation doses of 25Gy and 2mGy had no significant impact on the structure and enzyme activity. The dose of 25kGy caused a significant decrease in the enzyme activity and structural changes immediately after irradiation of ADH and after storage of irradiated HEWL at -20°C. The results emphasize the importance of careful selection of radiation doses for development of X-ray imaging methods as PAT tools inspection of solid biopharmaceutical products.

Study on feasibility of determination of glucosamine content of fermentation process using a micro NIR spectrometer

N-acetyl-d-glucosamine (GlcNAc) is a microbial fermentation product, and NIR spectroscopy is an effective process analytical technology (PAT) tool in detecting the key quality attribute: the GlcNAc content. Meanwhile, the design of NIR spectrometers is under the trend of miniaturization, portability and low-cost nowadays. The aim of this study was to explore a portable micro NIR spectrometer with the fermentation process. First, FT-NIR spectrometer and Micro-NIR 1700 spectrometer were compared with simulated fermentation process solutions. The Rc2, Rp2, RMSECV and RMSEP of the optimal FT-NIR and Micro-NIR 1700 models were 0.999, 0.999, 3.226 g/L, 1.388 g/L and 0.999, 0.999, 1.821 g/L, 0.967 g/L. Passing-Bablok regression method and paired t-test results showed there were no significant differences between the two instruments. Then the Micro-NIR 1700 was selected for the practical fermentation process, 135 samples from 10 batches were collected. Spectral pretreatment methods and variables selection methods (BiPLS, FiPLS, MWPLS and CARS-PLS) for PLS modeling were discussed. The Rc2, Rp2, RMSECV and RMSEP of the optimal GlcNAc content PLS model of the practical fermentation process were 0.994, 0.995, 2.792 g/L and 1.946 g/L. The results have a positive reference for application of the Micro-NIR spectrometer. To some extent, it could provide theoretical supports in guiding the microbial fermentation or the further assessment of bioprocess.

Development of a New Punch Head Shape to Replicate Scale-Up Issues on a Laboratory Tablet Press III: Replicating Sticking Phenomenon Using the SAS Punch and Evaluation by Checking the Tablet Surface Using 3-D Laser Scanning Microscope

Sticking is a common observation in the scale-up stage on the punch tip using a commercial tableting machine. The difference in the total compression time between a laboratory tableting machine and a commercial one is considered one of the main root causes of scale-up issues in the tableting processes. The proposed “Size Adjusted for Scale-up punch” can be used to adjust the consolidation and dwell times for commercial tableting machine. As a result, the sticking phenomenon is able to be replicated at the pilot scale stage. As reported in this article, the quantification of sticking was done using a 3-D laser scanning microscope to check the tablet surface. It was shown that the sticking area decreased with the addition of magnesium stearate in the formulation, but the sticking depth was not affected by the additional amount of magnesium stearate. It is proposed that the use of a 3-D laser scanning microscope can be applied to evaluate sticking as a process analytical technology tool, and so sticking can be monitored continuously without stopping the machine.

Monitoring mAb cultivations with in-situ raman spectroscopy: The influence of spectral selectivity on calibration models and industrial use as reliable PAT tool.

Raman spectroscopy is a suitable monitoring technique for CHO cultivations. However, a thorough discussion of peaks, bands, and region assignments to key metabolites and culture attributes, and the interpretability of produced calibrations is scarce. That understanding is vital for the long-term predictive ability of monitoring models, and to facilitate lifecycle management that comply with regulatory guidelines. Several fed-batch lab-scale mAb mammalian cultivations were carried out, with in situ Raman spectroscopy used for process state estimation and attribute monitoring. The goal was to evaluate its use as a process analytical technology (PAT) tool to detect residual glucose and lactate levels, understand their dynamics and interconversion, and eventually estimate key performance culture and product quality attributes. Glucose and lactate models were optimized up to 0.31 gL-1 with 3 Latent Variables (LVs) and 0.19 gL-1 (2 LVs) accuracy, respectively. Glutamine and product titer models, were not specific and accurate enough, even though indirect calibrations were obtained with a RMSEP of 0.12 gL-1 (4 LVs) and 0.29 gL-1 (5 LVs), respectively. A critical discussion and details about the extensive work done in calibration development and optimization are provided. Namely, considering a risk-based selection of variability sources impacting sample spectra, executing designed experiments with spiked cultivations, and using advanced chemometric procedures for variable selection and model cross validation. A strategy is presented to evaluation Raman spectroscopy as a reliable PAT technology fit-for industrial use. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:659-670, 2018.

Process analytical technology for monitoring pharmaceuticals freeze-drying – A comprehensive review

ABSTRACTThe goal of this paper is to review the available process analytical technology tools for monitoring the batch freeze-drying process for pharmaceuticals. These systems aim evaluating in-line product temperature, sublimation flow rate, and values of some model parameters in such a way that it can be used for in-line or off-line process optimization. A detailed survey of the systems proposed in the literature is presented, grouping them on the basis of monitored variable, namely, product temperature, heat flux to the product, sublimation flux, and, finally, other variables. The advantages and drawbacks of the techniques are critically assessed, taking into account the possibility of using them not only at lab-scale but also at production scale, beside, obviously, the possibility of getting reliable measurements of the desired variables.

Potential of Near-Infrared Chemical Imaging as Process Analytical Technology Tool for Continuous Freeze-Drying.

Near-infrared chemical imaging (NIR-CI) is an emerging tool for process monitoring because it combines the chemical selectivity of vibrational spectroscopy with spatial information. Whereas traditional near-infrared spectroscopy is an attractive technique for water content determination and solid-state investigation of lyophilized products, chemical imaging opens up possibilities for assessing the homogeneity of these critical quality attributes (CQAs) throughout the entire product. In this contribution, we aim to evaluate NIR-CI as a process analytical technology (PAT) tool for at-line inspection of continuously freeze-dried pharmaceutical unit doses based on spin freezing. The chemical images of freeze-dried mannitol samples were resolved via multivariate curve resolution, allowing us to visualize the distribution of mannitol solid forms throughout the entire cake. Second, a mannitol-sucrose formulation was lyophilized with variable drying times for inducing changes in water content. Analyzing the corresponding chemical images via principal component analysis, vial-to-vial variations as well as within-vial inhomogeneity in water content could be detected. Furthermore, a partial least-squares regression model was constructed for quantifying the water content in each pixel of the chemical images. It was hence concluded that NIR-CI is inherently a most promising PAT tool for continuously monitoring freeze-dried samples. Although some practicalities are still to be solved, this analytical technique could be applied in-line for CQA evaluation and for detecting the drying end point.

In situ monitoring of cocrystals in formulation development using low-frequency Raman spectroscopy

In recent years, to guarantee a quality-by-design approach to the development of pharmaceutical products, it is important to identify properties of raw materials and excipients in order to determine critical process parameters and critical quality attributes. Feedback obtained from real-time analyses using various process analytical technology (PAT) tools has been actively investigated. In this study, in situ monitoring using low-frequency (LF) Raman spectroscopy (10–200 cm−1), which may have higher discriminative ability among polymorphs than near-infrared spectroscopy and conventional Raman spectroscopy (200–1800 cm−1), was investigated as a possible application to PAT. This is because LF-Raman spectroscopy obtains information about intermolecular and/or lattice vibrations in the solid state. The monitoring results obtained from Furosemide/Nicotinamide cocrystal indicate that LF-Raman spectroscopy is applicable to in situ monitoring of suspension and fluidized bed granulation processes, and is an effective technique as a PAT tool to detect the conversion risk of cocrystals. LF-Raman spectroscopy is also used as a PAT tool to monitor reactions, crystallizations, and manufacturing processes of drug substances and products. In addition, a sequence of conversion behaviors of Furosemide/Nicotinamide cocrystals was determined by performing in situ monitoring for the first time.

In-line Fourier-transform infrared spectroscopy as a versatile process analytical technology for preparative protein chromatography

Fourier-transform infrared spectroscopy (FTIR) is a well-established spectroscopic method in the analysis of small molecules and protein secondary structure. However, FTIR is not commonly applied for in-line monitoring of protein chromatography. Here, the potential of in-line FTIR as a process analytical technology (PAT) in downstream processing was investigated in three case studies addressing the limits of currently applied spectroscopic PAT methods. A first case study exploited the secondary structural differences of monoclonal antibodies (mAbs) and lysozyme to selectively quantify the two proteins with partial least squares regression (PLS) giving root mean square errors of cross validation (RMSECV) of 2.42 g/l and 1.67 g/l, respectively. The corresponding Q2 values are 0.92 and, respectively, 0.99, indicating robust models in the calibration range. Second, a process separating lysozyme and PEGylated lysozyme species was monitored giving an estimate of the PEGylation degree of currently eluting species with RMSECV of 2.35 g/l for lysozyme and 1.24 g/l for PEG with Q2 of 0.96 and 0.94, respectively. Finally, Triton X-100 was added to a feed of lysozyme as a typical process-related impurity. It was shown that the species could be selectively quantified from the FTIR 3D field without PLS calibration. In summary, the proposed PAT tool has the potential to be used as a versatile option for monitoring protein chromatography. It may help to achieve a more complete implementation of the PAT initiative by mitigating limitations of currently used techniques.

Is the adjustment of the impeller speed a reliable attempt to influence granule size in continuous dry granulation?

As the field of continuous manufacturing of solid pharmaceutics is developing, the interest in implementing continuous granulation methods is growing. Process analytical technology tools should be integrated to ensure the monitoring of the product quality and therefore enforce control strategies.Three single materials which are often used in dry granulation and additionally two formulations, one containing ibuprofen and the other acetaminophen were processed at various process parameters. They all differed in their compaction and fracture behavior. A statistical analysis of the influence of process parameters was executed, to work out which parameters could be used for a granule size control approach in continuous dry granulation. Thereby, the specific compaction force and the impeller speed were found to be significant factors in each design of experiment. However, the impeller speed was evaluated as the only suitable parameter to control granule size, as an impact on granule density is unlikely. Nevertheless, some restrictions such as an upper impeller speed limitation to avoid excessive fines and a lower speed limitation to impede a downturn of the throughput, have to be considered. Furthermore, a decreasing median granule size was observed at higher throughputs for plastically deforming materials and formulations.

Headspace solid-phase microextraction (HS-SPME) combined with GC–MS as a process analytical technology (PAT) tool for monitoring the cultivation of C. tetani

Vaccine production is a biological process in which variation in time and output is inevitable. Thus, the application of Process Analytical Technologies (PAT) will be important in this regard. Headspace solid - phase microextraction (HS-SPME) coupled with GC–MS can be used as a PAT for process monitoring. This method is suitable to chemical profiling of volatile organic compounds (VOCs) emitted from microorganisms. Tetanus is a lethal disease caused by Clostridium tetani (C. tetani) bacterium and vaccination is an ultimate way to prevent this disease. In this paper, SPME fiber was used for the investigation of VOCs emerging from C. tetani during cultivation. Different types of VOCs such as sulfur-containing compounds were identified and some of them were selected as biomarkers for bioreactor monitoring during vaccine production. In the second step, the portable dynamic air sampling (PDAS) device was used as an interface for sampling VOCs by SPME fibers. The sampling procedure was optimized by face-centered central composite design (FC-CCD). The optimized sampling time and inlet gas flow rates were 10 min and 2 m L s−1, respectively. PDAS was mounted in exhausted gas line of bioreactor and 42 samples of VOCs were prepared by SPME fibers in 7 days during incubation. Simultaneously, pH and optical density (OD) were evaluated to cultivation process which showed good correlations with the identified VOCs (>80%). This method could be used for VOCs sampling from off-gas of a bioreactor to monitoring of the cultivation process.