Identification and Structural Characterization of Degradation Products of Linagliptin by Mass Spectrometry Techniques.

As part of the development and production of pharmaceuticals, the purity of Active Pharmaceutical Ingredients stands as a fundamental parameter that significantly influences the quality, safety, and efficacy of the final drug product. Impurities in Active Pharmaceutical Ingredients are various unwanted substances that can appear during the whole manufacturing process, from raw materials to the final product. These impurities can stem from multiple sources, including starting materials, intermediates, reagents, solvents, and even degradation products resulting from exposure to environmental factors such as heat, light, or moisture. Their presence can potentially compromise the therapeutic effect of the drug, introduce unexpected side effects, or even pose safety risks to patients. This study aims to conduct the forced degradation of linagliptin and subsequently attempt to identify the resulting degradants. The degradation procedures were carried out in accordance with the guidelines of the International Committee for Harmonization. The degradation profile of linagliptin was investigated under various conditions, including acid hydrolysis, alkaline hydrolysis, oxidation, heat, and light exposure, utilizing ultra-performance liquid chromatography connected to a photo array detector. Identification and characterization of the degradation products were achieved using an ultra-performance liquid chromatography coupled with a single quadrupole detector mass spectrometer and also a liquid chromatography coupled with a high-resolution mass spectrometry. The identified degradation products demonstrate that linagliptin is particularly susceptible to degradation when exposed to acid and peroxide. Whereas, no significant degradation effects were observed under alkali, thermolytic, and photolytic conditions.

Impurity identification in thiamethoxam by high resolution mass spectrometry and computer assisted elucidation.

Thiamethoxam (TMX) is a widely used neonicotinoid insecticide in pest control. Identification of structurally related impurities is very important during certified reference material development and pesticide registration, thus it needs to be carefully characterized. In this study, a combined strategy with liquid chromatography-high resolution mass spectrometry and computer assisted elucidation (SIRIUS) has been developed for the impurity elucidation in TMX material. MS and MS/MS spectra were used to score the impurity candidates by isotope score and fragment tree in SIRIUS. TMX, the main component, worked as an anchor for formula identification and structure elucidation of impurity. With this strategy, four impurities were identified, including two byproducts (TMX-OCH3 and TMX-Cl) and two metabolites (clothianidin and TMX-urea). Their fragmentation pathways were concluded, and mechanism of impurity formation was also proposed. This result showed successful application of combining human intelligence with machine learning in impurity identification from chemicals.

Exploring the versatility of mass spectrometry: Applications across diverse scientific disciplines.

Mass spectrometry (MS) has become a pivotal analytical tool across various scientific disciplines due to its ability to provide detailed molecular information with high sensitivity and specificity. MS plays a crucial role in various fields, including drug discovery and development, proteomics, metabolomics, environmental analysis, and clinical diagnostics and Forensic science. In this article we are discussing the application of MS across the diverse scientific disciplines by focusing on some classical examples from each field of application. As the technology continues to evolve, it promises to unlock new possibilities in scientific research and practical applications, cementing its position as an essential tool in modern analytical science.

Semi-preparative LC-SPE-cryoflow NMR for impurity identifications: use of mother liquor as a better source of impurities.

Unambiguous structural elucidation of active pharmaceutical ingredients (API) impurities is a particularly challenging necessity of pharmaceutical development, particularly if the impurities are low level (0.1% level). In many cases, this requires acquiring high-quality NMR data on a pure sample of each impurity. High-quality, high signal-to-noise (S/N) one- and two-dimensional NMR data can be obtained using liquid chromatography-solid phase extraction-cryoflow NMR (LC-SPE-cryoflow NMR) with a combination of semi-preparative column for separation and mother liquor as a source of concentrated impurities. These NMR data, in conjunction with mass spectrometry data, allowed for quick and unambiguous structural elucidations of four impurities found at low level in the crystallized API but found at appreciable levels in the mother liquor that was used as the source for these impurities. These data show that semi-preparative columns can be used at lower than ideal flow rates to facilitate trapping of HPLC components for LC-SPE-cryoflow NMR analysis without compromising chromatographic resolution. Also, despite the complex chromatography encountered with the use of mother liquor as a source of impurities, acceptably pure analytes were obtained for acquiring NMR data for unambiguous structure elucidations.

Refractive index-assisted UV/Vis spectrophotometry to overcome spectral interference by impurities.

A major challenge hindering the application of techniques like UV/Vis spectrophotometry in determining concentration is spectral interference from contaminants. Since molar absorptivities vary significantly, even minuscule amounts of specific contaminants may cause relatively large errors in UV/Vis spectrophotometry based quantification. Current methods to deal with this are slow, cost-intensive, or ineffective for unknown interferents. We propose constrained refractometry as an expedient technique to aid UV/Vis spectrophotometry, avoiding large errors due to spectral interference. Based on a modified Lorentz Lorenz equation, the technique helps not only in detecting and reducing error from unknown contaminants but also in identifying the significant impurity. Experimental results show a significant reduction of error in concentration determination even for multiple unknown interfering contaminants.

HPLC-Based Analysis of Impurities in Sapropterin Branded and Generic Tablets.

This work was aimed at the definition of a chromatographic method able to separate and quantify impurities present in sapropterin-containing drugs during an accelerated stability study. The chromatographic method was applied to the orphan drug Kuvan® and to its corresponding generic sapropterin Dipharma (Diterin®), both of which are approved for the treatment of hyperphenylalaninemia-induced symptoms. The two products tested had a similar manufacture date and both had an approved stability shelf-life of three years. Samples were analyzed by HPLC at T = 0 and after six months of storage at 40 °C and 75% relative humidity. Identification of the impurities was supported by a detailed mass spectrometry and MS/MS profile. The analysis demonstrated an overall higher stability for the Diterin® formulation, which was related to a lower increase of some impurities compared to Kuvan®.

[Identification of the impurity in auramine O by high performance liquid chromatography-ion trap-time of flight mass spectrometry and preparation of the auramine O reference standard by preparative high performance liquid chromatography].

A novel and effective method was established for the qualitative analysis of impurities in auramine O samples of illegal food additives using high performance liquid chromatography-ion trap-time of flight mass spectrometry (HPLC-IT-TOF-MS). An impurity was identified in the auramine O sample using the optimized HPLC-IT-TOF-MS method. According to the exact mass of each fragment ion measured by multistage MS, the structure of the impurity was determined to be that of 4-(imino (4-(methylamino) phenyl) methyl)-N,N-dimethylaniline hydrochloride. The synthetic route of the auramine O and the source of the identified impurity were proposed. Simultaneously, a preparative high performance liquid chromatography (prep-HPLC) technique was successfully applied for the purification of the auramine O from complex samples. Prep-HPLC columns with particle sizes of 10 µm and 5 µm were used for the separation and purification with injection volumes of 1 mL and 500 µL, respectively. Finally an auramine O reference standard with 99.52% purity was obtained by secondarily purification and determined by the analytical HPLC area normalization method. Deducting the 0.34% moisture content and 0.13% ash content, the final purity of the sample was 99.05%, as determined by mass balance method. The chemical structure was examined using UV, IR, LC-MS, and NMR. The developed method is simple and efficient, and can be applied for the preparation of reference standard materials for other illegal food additives.

[Qualitative identification of impurities and principal component quantitative analysis of zearalanone on purity certified reference material].

A liquid chromatography method was established for the determination of zearalanone (ZAN) raw material. The qualitative analysis of ZAN and its trace impurities was performed by ultra performance liquid chromatography-diode array detector (UPLC-DAD) and ultra performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS), and the response factors of each impurity were calculated. The three main organic impurities in the ZAN raw material were identified as ß -zearalanol, α -zearalanol and a dehydration product of zearalanol with relative response factors of 0.5352, 0.8594 and 0.6973, respectively. The main component of the ZAN raw material was determined by the calibration factor normalization method. The purity of zearalanone was determined to be 99.6% with a standard deviation of 0.01%. This method can provide a technical support for the development of ZAN standard materials.

[Identification of the impurities in o-chlorophenyl cyclopentyl ketone samples by high performance liquid chromatography-hybrid ion trap/time-of-flight mass spectrometry and preparation of o-chlorophenyl cyclopentyl ketone standard].

A method for the identification of relevant impurities in illegal o-chlorophenyl cyclopentyl ketone drug was developed. Identification of impurities could help regulation of this illegal drug and allow the sources of samples of the drug to be identified. An efficient and effective method for qualitatively analyzing samples using high performance liquid chromatography-hybrid ion trap/time-of-flight mass spectrometry (HPLC-IT/TOF MS) was developed. The o-chlorophenyl cyclopentyl ketone fragmentation pathway during HPLC-MSn was determined by analyzing a standard by HPLC-IT/TOF MS. The optimized HPLC-IT/TOF MS method allowed two impurities in o-chlorophenyl cyclopentyl ketone samples to be identified. According to the exact mass data of MSn and the element composition analysis, two impurities were identified as o-chlorobenzoic acid anhydride and 1,2-di-o-chlorobenzoylcyclopentene. The synthetic route of the o-chlorophenyl cyclopentyl ketone samples was proposed by analysis of these impurities. The established method made it easy to identify impurities and find the source of this illegal drug. A method for the preparation an o-chlorophenyl cyclopentyl ketone reference standard from actual samples using preparative HPLC was also developed. The mobile phase was methanol-water (85:15, v/v) and flow rate was 8 mL/min. The purity of the obtained standards, determined by analytical HPLC, was 99.53%. This method is simple, efficient, and can be used for the preparation of other illegal drugs.

Compatibility study of a parenteral microdose polyethylene glycol formulation in medical devices and identification of degradation impurity by 2D-LC/MS.

Polyethylene glycol (PEG) based formulation and polyvinylchloride (PVC) tubing are frequently used for drug delivery and administration. The compatibility of a parenteral drug microdose formulation in intravenous infusion (IV) devices was studied to support the clinical determination of absolute bioavailability by the microdosing method. The investigational microdose formulation containing PEG was found prone to significant loss of potency within hours of storage in the PVC IV tubing due to degradation. Degradation occurred only when both PEG and PVC tubing were present. The degradation product could not be detected by LC/MS due to the significant interference from the high concentration of PEG (4%) matrix and the extremely low level of drug (0.6ppm). To obtain structural information of the degradation impurity and understand the cause of the degradation, a simple heart-cutting 2D-LC/MS approach was utilized to effectively separate the impurity from the complex PEG oligomers and overcome the matrix interference, enabling mass spectrometric analysis of the impurity. An oxidation- dominated mechanism was proposed in which the combination of PEG auto-oxidation and dehydrochlorination of the PVC tubing yielded an oxidative environment that enhanced radical propagation and accelerated degradation of the investigational parent drug.

Current situation and the trend in impurity profiling of chemical drugs / 药学学报

Impurity profiling is one of the most important activities in both assuring drug safety and improving the quality of domestic drugs. Since the basic strategy of impurity profile control was put forward in 2010, a mature control procedure for impurity profile in drugs has been formed in China after nearly ten years of continuous efforts. The progress in impurity profiling before 2010 and from 2010 to 2015 have been reviewed. Since 2015, the concepts, analytical techniques and the application of these techniques in this field have developed rapidly. As a result, the progress in impurity profiling of chemical drugs since 2015 was reviewed in this paper. And the views on future development of impurity profiling in drugs were also put forward.

Evaluation of a compact mass spectrometer for routine support of pharmaceutical chemistry.

The suitability of a recently introduced inexpensive, compact mass spectrometer detector is evaluated for supporting pharmaceutical chemistry investigations. While high performance/high cost MS detectors dominate the marketplace, there is growing recognition of the need for a small, inexpensive MS detector with reduced capabilities for supporting synthetic chemistry investigations, where reduced sensitivity and unit mass resolution are often suitable for solving routine problems. In this study, the fundamental performance characteristics of the recently introduced Advion compact mass spectrometer were evaluated, investigating the use of the instrument for routine product and impurity identification, reaction monitoring, evaluation of potential genotoxic impurities and study of high molecular weight biomolecules. In general, the results of the evaluation show this compact and inexpensive mass spectrometer to be well suited for providing reliable support for pharmaceutical chemistry investigations, with sub-nanogram limit of detection and impurity identification below 0.1% being possible in some instance.