Process Impurities Research Articles

Development and Validation of Noscapine and Its Process Impurities by HPLC and Characterization of the Degradation Impurities by 2D‐LC–MS

ABSTRACTThe present study described the development and validation of a stability‐indicating HPLC method with two‐dimensional liquid chromatography–mass spectroscopy (2D‐LC–MS) for Noscapine in the presence of its process impurities and degradation products (DPs). The separation of the drug substance from the process impurities and DPs were obtained on a Gemini NX C18 column. The method employed a gradient elution using a mixture of 10 mM di sodium hydrogen phosphate dibasic buffer and acetonitrile (80:20, % v/v) as mobile phase A and acetonitrile as mobile phase B. The drug substance degraded into nine potential DPs (DP1–DP9). Each degradation impurity was fully characterized by 2D‐LC–MS/MS in ESI ionization mode with heart‐cutting technology in the 2D‐LC–MS. The developed RS and assay HPLC method was validated for linearity, accuracy, precision, specificity, and robustness. The results were met as per the ICHQ2. The developed HPLC method shall be used to determine the related substance and assay of Noscapine; it can be used for the quality of routine production samples. The greenness assessment of the method was presented with AGREE software. The developed and validated HPLC and 2D‐LC–MS were compared with 12 analytical greenness matric approach principles and found that the method was greeness with 0.76 green score. The detailed development, validation, identification, characterization, and green assessment were discussed in the manuscript.

A comprehensive study to identify major degradation products of avermectin active ingredient using high resolution LCMS and NMR

Avermectin (AVM) is the parent molecule of the family of macrocyclic lactone compounds that are generated by the bacterium Streptomyces avermitilis which exhibits a broad spectrum of activity and potency as a parasiticide. In this study, a comprehensive forced degradation study was carried out on AVM following ICH guidelines to identify and characterize its degradation products (DPs). AVM was subjected to acidic, alkaline, oxidative, thermal, and photolytic stress conditions. Forced degraded samples were analyzed using a gradient elution on an ACE UltraCore 2.5 SuperC18 column (150 × 4.6 mm, 2.5 µm particle size) to achieve sufficient separation of the active ingredient, impurities, and degradation products. AVM was susceptible to degradation under all conditions tested, with 7 major degradation products and one critical process impurity identified. Several minor degradation products and process impurities were also identified. The DPs were identified using liquid chromatography-high resolution mass spectrometry in comparison with the tandem mass spectrometry fragmentation profile of AVM B1a. Additionally, the identity of monosaccharide B1a, 8a-OH B1a, and 26-epimer B1a were elucidated through 1D and 2D nuclear magnetic resonance spectroscopy. Understanding the stability and degradation profile of Avermectin will allow for improved drug product formulations of not only Avermectin active ingredient but also be applicable to all compounds of the avermitilis family.

Study on the Impurity Profile and its Correlation with the Production Process in the Estazolam API and Tablets.

Estazolam is a benzodiazepine drug widely used in clinical practice. Currently, estazolam tablets on the Chinese market are generic drugs. To meet the requirements of national standards and uniformity, the impurity analysis methods were developed for active pharmaceutical ingredient (API) and tablets of estazolam. A high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method was developed to achieve enhanced sensitivity and resolution for the quantitative analysis of related substances. This method was applied to determine impurity levels in generic estazolam tablets from 12 Chinese manufacturers and APIs from 4 manufacturers. The liquid chromatography-tandem mass spectrometry(LC-MS/MS) method was used to determine the impurity profiles. The impurity content and impurity profiles were used as evaluation indicators to trace the correlation between the differences in impurity profiles and the production process. The content of both 8 known and unknown impurities was quantitatively determined by the HPLC-UV method. A principal component external standard method with correction factor was used for calculation, and detailed methodological validation was performed according to ICH guidelines. The structures of impurities in Chinese marketed products and the innovator drugs were qualitatively identified by the LC-MS/MS method, and differences in impurity profiles were compared. This study identified two USP-listed process impurities, two unknown process impurities, and one non-pharmacopeial degradation product. The unknown impurities were successfully separated and preliminarily characterized. Three API process impurities were key contributors to preparation impurity profile variations. Impurity levels showed close correlation with API synthesis routes and purification processes. A novel degradation product emerged during formulation, generated under light/heat stress, but minimally impacted tablet impurity variations. The optimized HPLC method demonstrated enhanced sensitivity and separation efficiency. API manufacturers should prioritize purification process optimization for impurities exceeding 0.1% thresholds to ensure drug safety.

Identification and Characterization of Interaction Product Impurities and Degradation Products of Atorvastatin Hot Melt Extrusion Formulation Using LC-HRMS/MS and ATR-IR.

Hot melt extrusion (HME) technology is widely used in pharmaceutical drug development to enhance the solubility and bioavailability of drugs. Atorvastatin (ATV) is a first-line statin for preventing cardiovascular disease, it has low oral bioavailability (14%), necessitating strategies to improve its bioavailability. This study involves identifying and characterizing interaction and degradation products formed during the HME process involving ATV and hydroxypropyl methylcellulose phthalate (HPMCP-55). It mainly focuses on identifying and characterizing unknown impurities and understanding their mechanisms. A simple, efficient, and mass spectrometry compatible high-performance liquid chromatography (HPLC) method was developed on a Welch XB C18 (4.6 × 150 mm, 3.5 μm) column using gradient elution of 10 mM ammonium acetate and acetonitrile as mobile phase. Further, attenuated total reflectance infrared spectrophotometry (ATR-IR) was also employed to investigate the interaction impurities formed between ATV and HPMCP-55 (imp-1,3) and degradation products (imp-2,4) formed during the extrusion process. LC-HRMS and ATR-IR analysis confirmed significant drug-polymer interactions during extrusion. Plausible impurity structures were elucidated via MS/MS fragmentation patterns and accurate mass. In silico toxicity prediction was performed using ProTox-II for all four impurities. The study underscores the importance of characterizing HME process impurities to understand drug stability, safety, and efficacy. This comprehensive approach facilitates thorough understanding of their potential interaction with drug candidates during the early phase of pharmaceutical development.

Characterization of time-dependent dielectric degradation and breakdown in bulk hexagonal BN/Si structures

Hexagonal boron nitride (h-BN) is a promising material for designing future electronic devices because of its superior dielectric properties. In this study, we fabricated bulk h-BN (sp2-bonded BN nano-network structure) on Si substrates using magnetically confined arc discharge plasma under various conditions. The effects of process gas conditions (Ar/N2 and N2) and impurity [tungsten (W)] incorporation were discussed. Regardless of the gas conditions, the presence of W atoms was found to significantly modulate the optical energy gap, which is supported by first-principles calculations. We investigated time-dependent dielectric breakdown (TDDB) mechanisms under constant voltage stress (CVS) and constant current stress (CCS). The time evolutions of the leakage current and the applied gate voltage during the TDDB measurements were analyzed to clarify the carrier-trapping and defect-generation mechanisms toward the final catastrophic dielectric breakdown. The field acceleration factors in the CVS-TDDB lifetime prediction fell within the general trend of SiO2-based films and were found to be a weak function of the gas condition and W concentration (CW), whereas the carrier-trapping and defect-generation dynamics during electrical stress depend on the gas conditions and CW. Based on the obtained results, we propose a prediction model for bulk h-BN degradation dynamics during CVS. We found that carrier trapping into preexisting sites and the probability of defect generation were enhanced by the bombardment of ions with higher energy during the bulk h-BN formation and a larger number of incorporated W atoms. These findings provide fundamental guidelines for the reliability assessment of bulk h-BN films for various applications.

DEVELOPMENT AND VALIDATION OF A STABILITY-INDICATING HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC METHOD FOR THE QUANTITATIVE DETERMINATION OF NITAZOXANIDE AND IT’S RELATED SUBSTANCES IN ACTIVE PHARMACEUTICAL INGREDIENTS

Objective: Nitazoxanide (NAT) is a veterinary antibiotic used for the treatment of protozoal infections in livestock and sheep. The estimation of NAT, its process impurities, and degradation products have not been reported till date. In this study, we aimed to develop and validate a chromatographic separation method for the determination of NAT, its process impurities, and related substances as per International Conference on Harmonization (ICH) guidelines. Methods: Chromatographic separation of process impurities such as 2-amino-5-nitro thiazole also called NAT-related substance A, aspirin, and degradation impurities such as salicylic acid and tizoxanide (TIZ) were separated by reverse-phase high-performance liquid chromatography using gradient elution. The separation of NAT and TIZ was most critical as they are structurally similar. The mobile phase consisted of a gradient elution containing a composition of acetonitrile and 2% orthophosphoric acid solution adjusted to pH 2.5 at a flow rate of 1 mL/min. Separation was achieved on a YMC Pack C8 L7 column with a run time of 40 min. The detection was carried out using a photodiode array detector and quantification was carried out at 210 nm. Forced degradation study was also conducted to confirm the specificity. The robustness and ruggedness of the method were evaluated. Results: The relative retention times (RRT) for aspirin, salicylic acid, NAT, and TIZ were 6.33, 6.52, 22.43, and 6.45, respectively, indicating good separation. The asymmetry factor for all the peaks is ranged from 1.1 to 1.2 indicating acceptable chromatography. The % recovery from spiked studies ranged from 90% to 110% for all the impurities when spiked in the range of 50–150% of their nominal concentrations. For all the known impurities, the limit of detection ranged from 0.06 to 0.20 parts per million (ppm) and the limit of quantification ranged from 0.19 to 0.61 ppm. Conclusion: The method was validated as per ICH guidelines and further was successfully applied for the quality evaluation of NAT in bulk active pharmaceutical ingredients.

Identification, separation and structural characterization of process impurity present in Doxepin hydrochloride and quantification by using high performance liquid chromatography

This study aimed to investigate a novel process-related impurity generated during the production of doxepin hydrochloride. A new high-performance liquid chromatography (HPLC) method with a gradient program was developed, revealing that the impurity eluted at approximately 1.5 RRT of the drug substance. Liquid chromatography-mass spectrometry (LC-MS) analysis identified the impurity with a molecular mass of 474.2. Further, the impurity generated during doxepin production was isolated using column chromatography, and its structure was confirmed as a dimer of doxepin through nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, and high-resolution mass spectrometry (HRMS). The impurity was effectively separated using an HPLC system equipped with a Zorbax Eclipse Plus C18 column ((250 × 4.6) mm, 5 μm) at a column temperature of 40°C. The mobile phase, consisting of 10 mM ammonium acetate and methanol, was delivered in gradient mode, with detection at 254 nm using a diode array detector (DAD). The HPLC method was validated for specificity, linearity, precision, accuracy, and detection threshold, yielding satisfactory results.

Neural stem cell-derived extracellular vesicles purified by monolith chromatography retain stimulatory effect on in vitro scratch assay.

Neural stem cell-derived extracellular vesicles purified by monolith chromatography retain stimulatory effect on in vitro scratch assay.

Unveiling New Process Impurities in Ripasudil Hydrochloride Dihydrate: Identification, Synthesis, and Characterization

Background: Ripasudil hydrochloride or 4-Fluoro-5-{[(2S)-2-Methyl-1,4-diazepan-1-yl] sulfonyl isoquinoline hydrochloride known as K-115 is used for the treat-ment of glaucoma and ocular hypertension. In the API industry, to achieve and ensure the quality of drug substances, there is a need for impurity identification, synthesis, and char-acterization. The impurities are formed during the process, either side reaction or degrada-tion or carried over from the starting material. Objectives: The present study explores two new process impurities of Ripasudil Hydro-chloride dihydrate, specifically Impurity-1(4-fluoro-5-{[(3R)-3-methyl-4-(2-nitrolbenzenesulfonyl)-1,4-diazepan-1-yl] sulfonyl} isoquino line) and Impurity-2 (4-fluoro-N, N-dimethyl isoquinoline-5-sulfonamide). These impurities are critical to the quality of both the drug substance and the final drug product. Methods: The API crude samples were subjected to LC-mass spectrometry for the identi-fication of unknown impurities and further based on the observed mass values, a strategic synthetic route was designed for the synthesis of unknown impurities. The synthetic routes for these impurities were developed to avoid column purification, achieving high yields and purity. Results: The above synthesized impurities were subjected to spectral analysis like mass spectrometry, 1H NMR, and 13C NMR and confirmed the desired structure of the unknown impurities. So, as far as we know, the two impurities are new process impurities and have not been reported in the literature. Conclusion: The two new process impurities have been prepared and used as impurities for the method development and quality evaluation of the Ripasudil drug substance. Given the regulatory significance of Ripasudil hydrochloride, our successful synthesis and char-acterization efforts have proven to be valuable. This research offers valuable insights into the generic pharmaceutical industry

Unique Research for Developing a Full Factorial Design Evaluated Liquid Chromatography Technique for Estimating Budesonide and Formoterol Fumarate Dihydrate in the Presence of Specified and Degradation Impurities in Dry Powder Inhalation.

A simple LC method has been developed and validated for estimating budesonide (epimer B + A) and formoterol fumarate dihydrate in dry powder inhalation. The development results of this study make it very significant. The degradation and process impurities in EP and ChP were identified in addition to budesonide and formoterol fumarate. As of yet, no one has reported all impurities using a single method. It is a unique research because it analyzes APSD (Aerodynamic Particle Size Distribution), DDU (Delivered Dose Uniformity), BU (Blend Uniformity), Assay, and cleaning test samples. It enhances the quality of medicine and separates all organic impurities and isomers through a suitable stationary phase (YMC-Pack Pro C18, 150 × 4.6 mm × 3 μm). We optimized the chromatographic conditions: Injection volume was 20 μL, and flow rate was 1.0 mL/min. The wavelength was optimized at 220 nm. After experimental and validation results. An example is A, which contains sodium dihydrogen orthophosphate monohydrate, sodium 1-decane sulfonate, adjusted pH 3.0, and acetonitrile at a ratio of 80:20 (v/v), and B, which contains pH 3.0 buffer and acetonitrile at a ratio of 20:80 (v/v) respectively. In addition to being optimized, the test method was validated according to ICH Q2(R2).

ADVANCES IN GAS CHROMATOGRAPHY FOR DETECTING PROCESS IMPURITIES: A COMPREHENSIVE REVIEW ON METHOD DEVELOPMENT, VALIDATION, AND SCALABILITY

Background:Gas chromatography (GC) remains a cornerstone in analytical chemistry, extensivelyemployed for the detection and quantification of process impurities, including volatile organic compounds (VOCs) and genotoxic impurities (GTIs) in pharmaceutical and industrial applications. Main Body:This review examines the evolution of conventional GC techniques with a focus on method development and validation in line with International Council for Harmonisation (ICH) guidelines. Special emphasis is placed on nitrosamines, scalability, cost-benefit analysis, and the integration of advanced technologies, as these aspects are pivotal in addressing modern analytical challenges.Nitrosamines, due to their carcinogenic potential, have become a focal point of regulatory scrutiny, demanding highly sensitive methods for trace-level detection. Scalability ensures that laboratory-developed GC methods can meet industrial-scale requirements efficiently. The cost-benefit analysis underscores the balance between analytical precision and economic feasibility, which is critical for widespread adoption. Additionally, the integration of advanced technologies such as sustainable practices not only enhances performance but also aligns with evolving environmental and industrial needs. Conclusion: By synthesizing recent advancements, this article highlights emerging challenges and future directions for GCs role in ensuring pharmaceutical quality and safety. Citations throughout emphasize the fields progress.

Synthesis, impurity profiling, simultaneous NP-HPTLC method development, molecular modelling study and EGFR tyrosine kinase inhibitory profile: An integrated approach to characterize desethynyl erlotinib process impurity

The study presents an integrated approach to characterizing Desethynyl Erlotinib, a process impurity in the synthesis of Erlotinib, a potent EGFR tyrosine kinase (EGFR TK) inhibitor used in lung cancer treatment. A normal phase high-performance thin-layer chromatography (NP-HPTLC) method was developed and validated for the simultaneous profiling of Erlotinib and its Desethynyl Erlotinib impurity. The optimized method utilized ethyl acetate, methanol, and glacial acetic acid (9: 0.5: 0.5 v/v/v) as the mobile phase for effective separation and quantification. The method demonstrated excellent linearity for Erlotinib and its impurity over a concentration range of 200-1200 ng/spot, with R2 values of 0.9979 and 0.9998, respectively. Validation confirmed precision with intra-day and inter-day % RSD values of less than 2% and robustness. The “limits of detection (LOD) and quantification (LOQ)” were 5.18 ng/spot and 15.70 ng/spot for Erlotinib and 7.07 ng/spot and 21.43 ng/spot for the impurity. In-vitro assays against the A549 lung cancer cell line expressing wild-type EGFR tyrosine kinase (WT EGFR TK) showed that the Desethynyl Erlotinib impurity exhibits significant inhibition compared to Erlotinib, suggesting the potential toxicity of the Desethynyl Erlotinib impurity and causing side effects such as diarrhea, skin rashes and interstitial lung disease due to WT EGFR tyrosine kinase (WT EGFR TK) inhibition. Molecular docking and molecular dynamics simulations further corroborated greater stability in the Desethynyl Erlotinib impurity with WT EGFR tyrosine kinase (WT EGFR TK). Clinically, these findings highlight the importance of monitoring and minimizing impurities like Desethynyl Erlotinib to prevent adverse effects and maintain the therapeutic safety of Erlotinib in lung cancer treatment. This research underscores the necessity for rigorous quality control in Erlotinib production to ensure purity and therapeutic effectiveness.

Simultaneous Quantitative Determination of Five Process Relevant Impurities in Menatetrenone

ABSTRACTMenatetrenone, a form of vitamin K (MK‐4) is used for various pharmaceutical and agrochemical applications. Monitoring and control of process impurities is crucial in the manufacturing of pharmaceutical‐grade Menatetranone. In this article, we report a gas chromatography (GC)‐based analytical method for the detection and quantification of trace levels of five process‐related impurities in MK‐4 originating from the starting materials and reagents. A GC‐flame ionization detector (GC‐FID)‐based method is presented for simultaneous quantitative estimation of five structurally diverse compounds, some of which are conventionally analyzed by liquid chromatography. After a series of method development trials, an optimized method with a mid‐polar column dura bond‐624 (6% cyanopropyl/phenyl and 94% polydimethylsiloxane) with initial column oven temperature 150°C, detector temperature 280°C was finalized for the separation of these impurities. The developed GC‐FID‐based method was validated for specificity, the limit of detection (LOD), the limit of quantification (LOQ), linearity, range, precision, accuracy, and robustness as relevant to the International Council for Harmonization guidelines. The method was found to be highly sensitive for all the constituents with an LOD ranging from 0.05 to 0.43 pg and a limit of quantification of 0.17–1.41 pg, as estimated by the signal‐to‐noise ratios. This is the first report of an analytical method for the simultaneous quantitative determination of five process impurities of MK‐4.

A new stability indicating HPLC method with QDa and PDA detectors for the determination of process and degradation impurities of ivabradine including separation of diastereomeric N-oxides.

In this study, a new reversed phase high performance liquid chromatography method using two detectors was developed for the analysis of degradation and process impurities of ivabradine in pharmaceutical preparations. A PDA detector set to 285 nm wavelength and a QDa detector set to positive scan mode were used in the method. In the developed method, the separation process was carried out in a Zorbax phenyl column with a gradient application of a 0.075% trifluoroacetic acid, acetonitrile, and methanol mixture at a flow rate of 1.5 ml min-1. During the degradation studies, the samples were exposed to acidic, alkaline, oxidative, thermal, and photolytic conditions. Process-related impurities were separated not only without interfering with each other but also with the degradation product and ivabradine peaks, and thanks to QDa, all impurities could be identified with their molecular weights. This method, in addition to providing stability data, was also able to separate two diastereomeric N-oxide impurities which are major oxidative degradation impurities of ivabradine having a chiral center. Some additional measurements such as solubility, specific rotation, melting point and differential scanning calorimetry analysis proved the formation of the two diastereomeric N-oxide impurities under oxidative conditions. Method validation was performed according to the International Council for Harmonization guidelines and the analysis of ivabradine, its process related impurities (dehydro ivabradine, acetyl ivabradine, and hydroxy ivabradine) and a major oxidative degradation product (ivabradine N-oxide) was successfully performed by this method.

Assessing the purity of model glycoconjugate vaccines by low field NMR.

Glycoconjugate vaccines are of growing importance to modern healthcare where they provide an opportunity for high efficacy prophylactic treatment against a growing number of infectious bacterial diseases. Unfortunately, their preparation is highly complex and involves multiple stages of analysis prior to product release. Such analyses must quantify the degree of successful conjugation and the amount of relevant co-expressed and co-purified process impurities (i.e. cell-wall polysaccharide). Whilst nuclear magnetic resonance (NMR) spectroscopy can be used for these assessments, the cost of high field systems is significant and hence there is a need to evaluate the performance of low-cost benchtop apparatus. Here, we set a goal of achieving a satisfactory analysis within 20 min on a series of model glycoconjugates and sought to use hyperpolarization methods based on signal amplification by reversible exchange (SABRE) to enable higher sample throughput. Our analyses demonstrate that a 1 Tesla (T) benchtop NMR can achieve satisfactory dextran-conjugation analysis results without the need for hyperpolarization, although SABRE hyperpolarization offers a route to improvement. The assessment of the common impurity cell-wall polysaccharide proved more challenging, and its hyperpolarization failed due to the necessary solvent system. At high field satisfactory analyses were possible at 10 wt%, 5 wt%, 1 wt% and 0.5 wt% loadings where the resulting signals are distinguishable. However, at 1 T signal overlap precluded simple signal integration and a T1 filter was implemented. This allowed the overlapping signal contributions to be differentiated and made quantification possible for the 10 wt% sample where signal to noise ratios remained high.

Fluorescent Reporter-Based Fiber Optic Probe for Continuous Detection of Antibodies.

Measurement of antibody and antibody fusion protein concentration is vital for process development and manufacturing. Continuous, in-line monitoring of antibody concentration could be useful in a variety of applications, such as controlling the loading of protein A columns to prevent breakthrough, monitoring bioreactor titer, and detecting leaks past ultrafiltration/diafiltration membranes. Molecule-specific monitoring techniques are advantageous for antibody detection in cell culture fluid in the presence of complex process impurities. Here we report a continuous in-line, real-time IgG monitoring platform using a fiber-optic biosensor with a replaceable sensor tip covalently functionalized with a fluor-labeled protein consisting of a pentamer of the Z domain (a more stable form of the B domain) of protein A. The sensor demonstrates concentration-dependent fluorescence enhancement in the presence of human IgG (0.01-0.75 g/L), with consistent signals during five runs each with 1 and 0.1 g/L IgG, and maintains its specificity in the presence of Chinese hamster ovary (CHO) cell culture fluid. A 5% breakthrough of a typical 10 g/L load would be detected in less than 20 s in a flowing stream emerging from a protein A column without prior sample preparation. This sensor platform may be suitable for monitoring IgG and fragment, crystallizable (Fc) fusion proteins in diverse upstream and downstream bioprocess applications.

Influence of Phosphorus on Initial and Long-Term Atmospheric Corrosion Behavior of Steel Materials

Phosphorus is contained as an impurity in the manufacturing process of steel materials, and it is known to be difficult to remove it completely, and it is also thought to influence the corrosion resistance of steel materials. However, the effect of phosphorus on corrosion resistance has not been clarified, because the steel materials used in previous research reports also contain copper and chromium. The aim of the present study was to systematically examine the influence of phosphorus on the corrosion behavior from early to long-term.Fe-P binary alloys containing 0.5, 1.0 and 1.5 mass% P were used as the samples. The sample grinded with SiC and diamond paste were prepared for electrochemical measurements. Anodic polarization measurements were performed in 25℃ of boric acid-borate buffer solution (pH 8.0) containing 10 mM NaCl in a non-deaerated environment. Platinum was used as the counter electrode and an Ag/AgCl electrode (3.33 M KCl) as the reference electrode. Before the polarization measurements, the immersion potential was measured for 10 min. and then cathodically treated at -1.0 V for 10 min. The sweep rate was 20 mV/min. In addition, the surface was observed by SEM and EDS after polarization at 0.2 V for 80 s to investigate the starting point of localized corrosion of the Fe-1.5 mass% P.EDS analysis was performed on all sample surfaces before electrochemical measurement. The distribution of phosphorus concentration was not observed on Fe-0.5 mass% P, whereas horizontal banded macro-segregation of phosphorus was observed on Fe-1.0 mass% P and Fe-1.5 mass% P. Furthermore, as a result of EDS analysis with a higher magnification, intergranular segregation of phosphorus was observed only on Fe-1.5 mass% P.In the anodic polarization curves of all samples, a peak was observed in the potential range of about -0.66 to -0.39 V, which could be attributed to the active dissolution of the sample. No increase of the current density was observed in the lower potential range than about 0.05 V, suggesting that the sample surface was passivated in this potential range. On the other hand, the current value increased significantly in the potential range higher than 0.05 V, due to the occurrence of localized corrosion. The current density of Fe-1.5 mass% P increased at lower potentials than for the other samples.Polarization measurement of Fe-1.5 mass% P was conducted at a constant potential to investigate the starting point of localized corrosion. A rapid increase in anode current was observed after approximately 10 seconds. SEM observations and EDS analysis were conducted on the sample surface after the test. A number of localized corrosion of about 5 µm in size was observed on the sample surface after the test. EDS analysis showed that higher concentrations of Si and Mn were detected in the corroded areas. In addition, localized corrosion with an elongated shape was also observed on the Fe-1.5 mass% P surface. Since no alloying elements (Mn and Si) derived from inclusions were detected in the corroded areas, this localized corrosion is considered to be due to intergranular segregation of P.The exposure test of all samples was conducted at Miyakojima Island, Japan for 5 years. The corrosion loss of Fe-1.5 mass% P was the smallest compared to the other samples, suggesting that the higher the P content, the lower the corrosion loss. EPMA analysis was conducted for the cross-section of the rust layer of samples after long-term exposure. P was partly concentrated in the rust layer of Fe-0.5 mass% P, but Cl penetrated into the rust layer and reached the steel substrate. On the other hand, P was fully enriched in the rust layer of Fe-1.5 mass% P and Cl was present only on the surface of the rust layer. The protective function of the rust layer due to phosphorus enrichment may have contributed to the long-term improvement of corrosion resistance.

Development and validation of a robust RP-HPLC method to quantitate residual 2–mercaptoethylamine in drug product formulations containing amino acid additives

Development and validation of a robust RP-HPLC method to quantitate residual 2–mercaptoethylamine in drug product formulations containing amino acid additives

Identification of a Novel Process Impurity, Root Cause Investigation, and Its Control Strategy in Process Chemistry of Nevirapine API

Identification of a Novel Process Impurity, Root Cause Investigation, and Its Control Strategy in Process Chemistry of Nevirapine API

Chromatographic analysis of ponatinib and its impurities: method development, validation, and identification of new degradation product.

Ponatinib, a third-generation tyrosine kinase inhibitor, is employed in the management of adult chronic myeloid leukemia. Nevertheless, the presence of process impurities and degradation impurities linked to ponatinib may potentially influence its effectiveness and safety. Therefore, the objective of this research was to establish a robust liquid chromatography method and systematically validate it for the detection of substances related to ponatinib. The separation of ponatinib and its impurities was conducted using an Agilent 5HC-C18 chromatographic column (4.6mm × 250mm, 5μm). The mobile phase A comprised a mixture of water and acetonitrile in a 9:1 ratio, with an aqueous solution of pH 2.4 containing 2mM potassium dihydrogen phosphate and 0.4% triethylamine. Mobile phase B, consisting of acetonitrile, was eluted in a gradient fashion. The flow rate was set at 1.0mL/min, detection wavelength at 250nm, column temperature at 40°C, and injection volume at 10μL. The method demonstrated high specificity, sensitivity, solution stability, linearity, precision, accuracy, and robustness. Additionally, this research unveiled a novel compound, imp-B, generated via the oxidative degradation of ponatinib. The molecular structure of the newly discovered product was elucidated through the utilization of nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). In conclusion, the chromatographic method developed in this study has the potential to be utilized for the detection of ponatinib and its impurities, thereby offering significant insights for quality assessment in ponatinib research.