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Impurity is an unwanted substance present in the active pharmaceutical ingredients that form during the synthesis process of active pharmaceutical ingredients or any unwanted constituent that is produced besides the active ingredient during the formulation or the aging of active pharmaceutical ingredients. Even the insignificant quantity of impurity existing in the medicinal product may harm the patient life and compromises the purity and superiority of the medicinal product. According to International council for harmonisation guidelines, analytical monitoring of impurity is a prerequisite and mandatory requirement for approval of market authorization of the new drug substance. Any pharmaceutical product would be capable to serve their intended therapeutic activity when they are free from impurity. Thus, an impurity existing in an active pharmaceutical ingredient needs to be identified and quantify with the help of modern analytical approaches. This review explores the basic information concerning impurity profiling, highlights the advantages of an analytical technique and also focuses on the limitation of different analytical methods for impurity profiling with possible ways to overcome the limitation. [ABSTRACT FROM AUTHOR]

A capillary zone electrophoresis method was developed for the determination of NiII(3-OMe-salophene), a substance with anticancer activity in vitro. A fused silica capillary (56 cm × 100 µm) was used for this purpose. The method was optimized in terms of parameters affecting the electrophoretic conditions in order to optimize separation efficiency and total time of migration. The analysis was best performed using an operating buffer of 50 mM borate, adjusted to pH 9.3, mixed with acetonitrile (50%, v/v) as organic modifier. Injections were performed hydrodynamically by applying a pressure of 50 mbar for 8 s, and a 30 kV separation voltage was selected at 25 °C. Detection was carried out at 250 nm using diode array detector (DAD). The method allowed the separation of NiII(3-OMe-salophene) from four other structurally related impurities in a total migration time (tm) of 8 min. Peak identification was achieved using the standard reference of individual impurities. The purity of the migrated NiII(3-OMe-salophene) was confirmed by Ultra-violet (UV) scan overlay depending on DAD. The linear ranges for the determination of NiII(3-OMe-salophene) was 400–20,000 ng mL−1 with limit of detection (LOD) of 120 ng mL−1. Acceptable intra-day and inter-day precisions were achieved (%relative standard deviation (RSD) results were less than 0.76% and 0.30%, respectively). The proposed method was assessed for greenness and compared to reported methodologies to prove superiority.

Currently, analytical scientists are paying special attention to reducing reliance on hazardous chemicals in various analytical methods. By embracing this concept, we developed an eco‐friendly high‐performancethin‐layer chromatography (HPTLC) method as an alternative for the conventional HPLC method for the determination of an essential human micronutrient, niacin (NIA), which is used improve the lipid profile of patients. Furthermore, the proposed HPTLC method is capable of determining the structurally related impurities of NIA such as pyridine‐2,5‐dicarboxylic acid, isonicotinic acid, pyridine, and 5‐ethyl‐2‐methylpyridine, which exhibit nephrotoxic and hepatotoxic effects. The separation of this challenging mixture was achieved on HPTLC sheets using a mixture of ethyl acetate/ethanol/ammonia solution (6:4:0.05, v/v/v), and then the dried plates were scanned at 254 nm. The analytical eco‐scale assessment protocol was used to assess the greenness profile of the presented method and compare it with the reported HPLC method. The suggested method was found to be greener with regard to the consumption of solvents and the yielding of waste. The results suggest that the described method can be safely implemented for the routine analysis of NIA pharmaceutical dosage without the interference of potential impurities in quality control laboratories. [ABSTRACT FROM AUTHOR]

Dasatinib is a protein kinase inhibitor used for the treatment of chronic myelogenous leukemia and acute lymphoblastic leukemia. Dasatinib along with its six known organic impurities were separated using the reversed-phase high performance liquid chromatography with C18 column and mobile phases consisting of gradient mixture of 20 mM potassium phosphate buffer at pH 6.0 with 1-octanesulphonic acid sodium salt (0.1%, w/v), acetonitrile and ultrapure water. This method was successfully tested with liquid chromatography coupled mass-spectrometry to elucidate the chemical structure of newly formed degradation product of Dasatinib which was identified by comparing its retention time and mass-spectra with literature data. Stability-indicating characteristics of developed HPLC method was assessed using stress testing [5 N HCl at 90 °C/1 h, 5 N NaOH at 90 °C/1 h, H2O at 90 °C/1 h, 30% H2O2 (w/w) at 25 °C ± 5 °C/1 h, dry heat at 105 °C/24 h and UV (200 W h m−2) and fluorescent light (1.2 million lux-h)] and was validated as per ICH Q2(R1). For Dasatinib and its six impurities, the quantification limits, linearity and recoveries were found in range of 0.19–0.21 μg/mL, 0.2–3.0 μg mL−1 (R2 > 0.995) and 85.5–107.0%, respectively. The developed HPLC method will also suffice the suitability for impurity profiling and assay of Dasatinib in bulk drugs and pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

Degradation studies of drug give insightful information about the intrinsic stability of the molecule, the possible degradents formed during shelf life and thus, aid in the subsequent development of its stable formulation. For identification and characterization of degradents and impurities formed during stress studies, various analytical techniques are required including hyphenated techniques. Chromatographic methods play a crucial role in the field of degradation and impurity profiling. Many of these methods have been introduced for the qualitative and quantitative analysis of drugs and their formulations. This article encompasses current trends in analytical methods used for degradents, foreign matter, genotoxic impurity, and impurity profiling studies of the last five years (2013–2017). It further provides an insight into the development of various analytical methods such as hyphenated and non-hyphenated techniques those used in the analysis of pharmaceuticals. Various components used in chromatographic development such as mobile phase, buffer solutions, elution modes, columns, column temperature, and detectors are emphasized. Techniques developed by systematic Analytical Quality by Design (AQbD) approach are also discussed. Additionally, the in silico toxicity prediction studies and the methods developed for genotoxic impurity analysis are briefly explained. [ABSTRACT FROM AUTHOR]

In this study, we utilized elemental analyser (EA) and gas-chromatography (GC) isotope ratio mass spectrometry (IRMS) and ultra-high-performance liquid chromatography coupled to mass spectrometry (UHPLC-MS) in a comprehensive profiling approach assessing the chromatographic impurity signatures and δ13C and δ15N isotope ratios of synthetic cannabinoids from police seizures and internet test purchases. Main target of this study was the highly prevalent synthetic cannabinoid MDMB-CHMICA (methyl (2S)-2-([1-(cyclohexylmethyl)-1 H -indol-3-yl]formamido)-3,3-dimethylbutaoate). Overall, 61 powder and 118 herbal blend (also called "Spice-Products") samples were analysed using both analytical techniques and evaluated in a joint model to link samples from a common source. As a key finding, three agglomerates of Spice-product samples with similar dates of purchase were identified in the IRMS data, possibly representing larger shipments of MDMB-CHMICA, each produced with the same precursor material, successively delivered to the European market. The three agglomerates were refined into multiple sub-clusters based on the impurity profiling data, each representing an individual synthesis batch. One of the agglomerates identified in the IRMS data was found to consist two groups of four sub-clusters, respectively, with majorly different impurity profiles, demonstrating the necessity for both analytical techniques to extract the maximum amount of information from a limited sample pool. Additionally, 31 samples containing the recently surfaced synthetic cannabinoid Cumyl-PeGaClone (5-pentyl-2-(2-phenylpropan-2-yl)-2,5-dihydro-1 H -pyrido[4,3-b]indol-1-one) were analysed for their and δ13C and δ15N isotope ratios to put the isotopic data recorded for MDMB-CHMNICA in a more global perspective. Three building blocks of precursor chemicals (indole, tert-leucine, cumylamine) potentially used for the synthesis of the two named synthetic cannabinoids were acquired from different global vendors and measured for their δ13C and δ15N isotope ratios to better understand variations in the isotopic composition of the synthetic cannabinoids and to trace their origin. Image 1 • Combination of stable isotope ratio mass spectrometry and organic impurity profiling. • Analysis of two highly prevalent synthetic cannabinoids: MDMB-CHMICA and Cumyl-PeGaClone. • Origin of precursor compounds for identification of a common source, fine structure of samples by impurity profiling. • European market seems to be supplied by larger batches of pure synthetic cannabinoid in intervals of multiple month. • Cooperation between internet-shops is expected. [ABSTRACT FROM AUTHOR]

Zidebactam (ZID) is a novel drug in clinical development; it potentiates the antibacterial activity of β-lactam antibiotics. Two reversed phase liquid chromatographic (RP-LC) methods were developed for ZID; a mass spectrometer (MS) compatible method for identification and another UV detection method for the quantification of impurities. Four impurities and three degradation products (DPs) were identified using LC–MS/MS. Both methods were developed on Hydrosphere C18 stationary phase which was found to be unique for the purpose due to its hydrophilic surface. The chromatographic separation of ZID and impurities was achieved in gradient mode using mobile phase consisting of ammonium formate in LC–MS/MS studies and ammonium dihydrogen phosphate in UV method. Acetonitrile (ACN) was employed as an organic solvent. ZID was subjected to hydrolytic, oxidative, photolytic and thermal stress conditions. The degradation was observed in acidic, basic and oxidative conditions. The UV method was validated. The method was accurate and precise to quantify impurities; accuracy was greater than 99.8% with precision of less than 4%. The method was highly sensitive to detect impurities as low as 1.4 ng on column. The developed method was employed for quality control and stability studies of the new drug substance during pre-clinical and clinical studies. The same method was also adapted for analysis of a parenteral drug product. [ABSTRACT FROM AUTHOR]

The azithromycin is a semisynthetic derivative of erythromycin A, and commercially produced by a series of chemical reaction involved Beckmann rearrangement followed by reductive methylation. Several azithromycin related compounds (ARCs) have been identified as impurity in the commercial products and the processes. These ARCs probably generated from impure starting material; a mixture of different erythromycin. Literature search revealed that approximately 90 erythromycins had been isolated and characterized so far. In current study, we have identified many new ARCs, including previously reported by detailed LC-MS/MS studies. In this study, first, the structures of ARCs were assumed by probable chemical transformation method; erythromycin A to azithromycin A; and, second, assumed structures of ARCs were confirmed by HRMS within the acceptable ppm error limit (±5 ppm) followed by MS/MS fragmentation to identify the characteristic common ion fragments and by precursor ion scan. [ABSTRACT FROM AUTHOR]

Two-dimensional liquid chromatography requires orthogonal columns and/or separation principles in the first and second separation dimension. It is sometimes not straightforward to achieve. Chiral columns could expand the toolbox for 2D-LC, but are rarely exploited for this purpose, not least due to missing understanding of retention principles under non-chiral application conditions. To gain more insight, in this study Chiralpak ZWIX(+) and ZWIX(−), based on zwitterionic quinine and quinidine carbamate selectors, were carefully characterized by molecular dynamics simulations, lipophilicity/hydrophilicity measurements of selectors, pH-dependent ζ-potential determinations, and chromatographic characterization in RPLC and HILIC modes combined with unsupervised principal component analysis to extract classification of these columns in comparison to a number of commercial benchmarks (RP, HILIC and mixed-mode columns). The results showed that these chiral columns can be classified as mixed-mode chromatography phases with balanced lipophilic-hydrophilic surface character, excess of negative net charge due to sulfonic acid groups (in spite of weakly basic quinuclidine and quinoline rings), and multimodal applicability (RP, HILIC and polar organic elution modes). Orthogonality mapping in comparison to a number of modern HILIC and mixed-mode columns revealed that Poroshell HILIC-Z (with a zwitterionic ligand on 2.7 μm core-shell particles) can be beneficially combined as second dimension with the ZWIX column for comprehensive LC × LC. The online hyphenation of this 2D-LC system with complementary detection modalities including UV (DAD for chromophoric substances), charged aerosol detection (for universal detection and calibration of non-volatile analytes) and high-resolution mass spectrometry (ESI-QTOF-MS/MS for identification) provided an advanced method for comprehensive impurity profiling, applicable for instance for amino acid pharmaceutical products. Image 1 • New insights in physicochemical character of commercial Chiralpak ZWIX columns obtained. • Negative surface charge of zwitterionic stationary phases revealed by ζ-potential determination. • Benchmarking study with commercial RP, HILIC and mixed-mode phases classifies Chiralpak ZWIX(+/-) as mixed-mode chromatography columns with multiple elution modes. • LC × LC with Chiralpak ZWIX in polar organic elution mode as 1D and Poroshell HILIC-Z in HILIC as 2D established. • Full comprehensive LC × LC with three complementary detection modes (UV, CAD, QTOF-MS/MS) for amino acid impurity profiling. [ABSTRACT FROM AUTHOR]

The pre‐precursor market and the clandestine production of amphetamine‐type stimulants (ATS) has become more diverse in recent years. Besides α‐phenylacetoacetonitrile (APAAN) and α‐phenylacetoacetamide (APAA), glycidic acid derivatives and methyl α‐phenylacetoacetate (MAPA) are gaining importance. This conclusion is based on seizure data of police and customs. However, analytical data are needed to confirm and quantify the actual prevalence of new pre‐precursors by elucidating the percentage of seized ATS that have been produced from them. A recent study showed that APAAN use is currently declining, which supports the view that new pre‐precursors are being used. In this study, several conversion procedures using different batches of glycidic acid derivatives and a complete Leuckart reaction to produce amphetamine were carried out. The resulting organic phases were analyzed using gas chromatography − mass spectrometry to identify possible marker compounds. Three marker compounds were discovered and characterized using mass spectra and nuclear magnetic resonance spectroscopy. They were identified as phenyl‐1‐propanone, N‐(1‐phenylpropyl)formamide and 1‐phenylpropan‐1‐amine. Their prevalence was investigated by searching the markers in an amphetamine impurity profiling database to determine to what extent they occurred in amphetamine samples from recent years. Data from the central German amphetamine profiling database of more than 250 cases were used for this purpose. The yearly occurrence of the three glycidate marker compounds was determined going back as far as 2009, revealing an increasing trend from 2016 on. This article presents experimental proof that APAAN is currently being replaced by other pre‐precursors, such as glycidic acid derivatives. [ABSTRACT FROM AUTHOR]

Vaping of synthetic cannabinoids via e‐cigarettes is growing in popularity. In the present study, we tentatively identified 12 by‐products found in a pure sample of the synthetic cannabinoid Cumyl‐5F‐PINACA (1‐(5‐fluoropentyl)‐N‐(2‐phenylpropan‐2‐yl)‐1H‐indazole‐3‐carboxamide), a prevalent new psychoactive substance (NPS) in e‐liquids, via high‐resolution mass spectrometry fragmentation experiments (HRMS/MS). Furthermore, we developed a procedure to reproducibly extract this synthetic cannabinoid and related by‐products from an e‐liquid matrix via chloroform and water. The extracts were submitted to flash chromatography (F‐LC) to isolate the by‐products from the main component. The chromatographic impurity signature was subsequently assessed by ultra‐high‐performance liquid chromatography coupled to mass spectrometry (UHPLC–MS) and evaluated by automated integration. The complete sample preparation sequence (F‐LC + UHPLC–MS) was validated by comparing the semi‐quantitative signal integrals of the chromatographic impurity signatures of five self‐made e‐liquids with varying concentrations of Cumyl‐5F‐PINACA [0.1, 0.2, 0.5, 0.7 and 1.0% (w/w)], giving an average relative standard deviation of 6.2% for triplicate measurements of preparations of the same concentration and 10.5% between the measurements of the five preparations with different concentrations. Lastly, the chromatographic signatures of 14 e‐liquid samples containing Cumyl‐5F‐PINACA from police seizures and Internet test purchases were evaluated via hierarchical cluster analysis for potential links. For the e‐liquid samples originating from test purchases, it was found that the date of purchase, the identity of the online shop, and the brand name are the critical factors for clustering of samples. [ABSTRACT FROM AUTHOR]

Aclidinium bromide (ACL) is a long-acting muscarinic receptor antagonist used for the long-term treatment of chronic obstructive pulmonary disease (COPD). The aim of this study was to investigate the degradation of aclidinium bromide under stress and stability testing conditions, for which we developed and validated the first stability-indicating, specific, precise, accurate, and robust assay and related substances HPLC methods. Nine of the compounds used as reference standards were synthesized and fully characterized by 1H and 13C NMR, MS, and FTIR techniques. Two of these molecules, namely ACL-dimer and ACL-desphenyl, are novel compounds and reported herein for the first time. Hydrolysis of aclidinium resulted in major degradation via the formation of ACL-desDTG and DTGA metabolites. ACL-desphenyl and phenol were observed only under oxidative conditions at very low levels (< 0.10%), while ACL-hydroxy, known as a metabolite of aclidinium and confirmed by LC/QDa and LC/Q-TOF m/z data, formed under oxidative stress-testing conditions, UV light, and daylight. The identification of two impurities formed only when aclidinium bromide was treated with hydrogen peroxide was done by LC/QDa and LC/Q-TOF studies and the novel structures were proposed as ACL-bromophenoxy and ACL-bromothiophenyl formed via bromination of the phenyl and thiophene ring on the aclidinium, respectively. The stress and photostability testing studies showed that the aclidinium bromide drug substance is not sensitive to elevated temperature (105 °C, 10 days), slightly sensitive to daylight and UV-radiation, and it showed significant degradation under all hydrolysis and oxidizing conditions. The related substances HPLC method reported herein is also capable to monitor the potential genotoxic impurity 3-bromopropoxybenzene (3-BPB), a class 2 impurity according to ICH M7, and ensures that the impurity remains below the threshold of toxicological concern (TTC) limit, making it safe for patients. [Display omitted] • Stability-indicating related substances & assay HPLC methods for aclidinium bromide. • Evaluation, synthesis, and characterization of nine compounds by NMR, MS, and FTIR. • Degradation of aclidinium bromide studied under stress test conditions. • Identification of degradation impurities by LC-MS & discussion of formation pathways. • Four new compounds described for the first time in the literature. [ABSTRACT FROM AUTHOR]

• 2D-LC separation of oligonucleotides using IPRP separations in both dimensions. • Elution conditions are systematically discovered through iterative retention modeling. • 2D-LC separations provide both the selectivity and sensitivity needed for impurity profiling. • Application to therapeutic siRNA single strands from solid phase oligonucleotide synthesis. Oligonucleotides constitute an emerging and highly complex bioanalytical challenge and it is becoming increasingly clear that 1D methodologies are unable to fully resolve all possible impurities present in these samples. 2D-LC therefore constitutes a perfect solution wherein critical pairs can be sampled from a steep gradient 1D and separated in a shallower 2D gradient. Herein, we provide a facile 2D-LC method development approach to quickly generate high selectivity gradients utilizing ion pairing reverse phase (IPRP-IPRP). In particular we demonstrate how to iteratively generate a 12 % gradient from two training runs and then to utilize that data to predict retentions of analytes with a 2 % gradient with retention prediction errors as low as 3 and 11 %, respectively. This iterative method development workflow was applied to impurity profiling down to 1:1000 for the full-length product and phosphorothioate modified impurities. Additionally, we demonstrated the elucidation of critical pairs in complex crude pharmaceutical oligonucleotide samples by applying tailored high selectivity gradients in the second dimension. It was found that the iterative retention modeling approach allows fast and facile 2D-LC method development for complex oligonucleotide separations. [ABSTRACT FROM AUTHOR]

Chemical attribution signatures (CAS) can be used to obtain useful forensic information and evidence from illicit drug seizures. A CAS is typically generated using hyphenated chemical analysis techniques and consists of a fingerprint of the by-products and additives present in a sample. Among other things, it can provide information on the sample's origin, its method of production, and the sources of its precursors. This work investigates the possibility of using multivariate CAS analysis to identify the synthetic methods used to prepare seized fentanyl analogues, independently of the analogues' acyl derivatization. Three chemists working in two labs synthesized three different fentanyl analogues, preparing each one in duplicate by six different routes. The final collection of analogues (96 samples) and two intermediates (16 + 32 samples) were analysed by GC-MS and UHPLC-HRMS, and the resulting analytical data were used for multivariate modelling. Independently of analogue structure, the tested fentanyls could be classified based on the method used in the first step of their synthesis. The multivariate model's ability to classify unknown samples was then evaluated by applying it to six new fentanyl analogues. Additionally, seized fentanyl samples was analysed and classified by the model. Image 1 • Fentanyl analogues and its precursor, NPP and ANPP were analysed. • A model that could reliably predict the method of fentanyl synthesis were developed. • Seized fentanyl analogues were analysed and its synthetic method determined. [ABSTRACT FROM AUTHOR]

Background: Impurities in commonly used illicit drugs raise concerns for unwitting consumers when pharmacologically active adulterants, especially new psychoactive substances (NPS), are used. This study examines impurities detected in illicit drugs seized in one Australian jurisdiction.Methods: Queensland Health Forensic and Scientific Services provided analytical data. Data described the chemical composition of 9346 samples of 11 illicit drugs seized by police during 2015-2016. Impurities present in primary drugs were summarized and tabulated. A systematic search for published evidence reporting similar analyses was conducted.Results: Methamphetamine was the primary drug in 6608 samples, followed by MDMA (1232 samples) and cocaine (516 samples). Purity of primary drugs ranged from ∼30% for cocaine, 2-CB and GHB to >90% for THC, methamphetamine, heroin and MDMA. Methamphetamine and MDMA contained the largest variety of impurities: 22 and 18 variants, respectively. Drug adulteration patterns were broadly similar to those found elsewhere, including NPS, but in some primary drugs impurities were found which had not been reported elsewhere. Psychostimulants were adulterated with each other. Levamisole was a common impurity in cocaine. Psychedelics were adulterated with methamphetamine and NPS. Opioids were quite pure, but some samples contained methamphetamine and synthetic opioids.Conclusions: Impurities detected were mostly pharmacologically active adulterants probably added to enhance desired effects or for active bulking. Given the designer nature of these drug cocktails, the effects of the adulterated drugs on users from possible complex multi-drug interactions is unpredictable. Awareness-raising among users, research into complex multi-drug effects and ongoing monitoring is required. [ABSTRACT FROM AUTHOR]

In this work, the most discriminating synthesis‐related impurities found in samples from seizures and controlled synthesis of the synthetic cannabinoid MDMB‐CHMICA (methyl (S)‐2‐(1‐(cyclohexylmethyl)‐1H‐indole‐3‐carboxamido)‐3,3‐dimethylbutanoate) were characterized. Based on 61 available powder samples of MDMB‐CHMICA, 15 key‐impurities were assessed, isolated in larger quantities via flash chromatography and structurally elucidated and characterized via high resolution mass spectrometry and nuclear magnetic resonance spectroscopy. Apart from verifying the relation of the impurities to the major component, the interpretation of their chemical structures with distinct structural elements provided first insights into the manufacturing process and the precursor compounds used. Following liquid chromatography mass spectrometry analysis of the 15 key‐impurities, the 61 seized samples of MDMB‐CHMICA were evaluated and classified via multivariate data analysis based on the corresponding relative peak areas. In a second part of this work, stability tests and multiple controlled syntheses of MDMB‐CHMICA were carried out to better understand variations in impurity signatures and to assess the significance of variations in the impurity patterns of seized samples. The last coupling step of the amino acid with 1‐(cyclohexylmethyl)‐1H‐indole‐3‐carboxylic acid was performed using the coupling agents oxalyl chloride, thionyl chloride, and HATU. Furthermore, the impact of reaction time and temperature on the impurity profile were investigated. Overall, eight new impurities were found in the controlled syntheses and two degradation products of MDMB‐CHIMCA were found in the course of the stability tests. Replicates of a synthesis conducted on the same day showed similar impurity signatures; on different days they showed discriminable signatures. The use of different coupling reagents or conditions gave clearly distinguishable impurity signatures. [ABSTRACT FROM AUTHOR]

Although analytical HPLC-technique can be considered as a well-accepted versatile approach for the drugs' separation, quantification, as well as impurity profiling, its regular adoption shows increasing environmental concerns provoked by high energy-consumption, instrument and solvents costs, and generated wastes. Regarding such concepts, the decision to move into greener alternatives has become inevitable. High performance thin-layer chromatography (HPTLC) has been drawing scientists' attention as a powerful greener candidate to replace HPLC. HPTLC-plates offer improved resolution and shorter analysis time through reduced silica particles' size. HPTLC's silica stationary phase is characterized mostly by the ability to be renewed and re-invented endlessly which is the core of the sustainability concept. In consequence, HPTLC is characterized by its ability for simultaneous analysis of many samples in a parallel manner, resulting in high sample throughput, and lower solvent and energy consumption per sample when compared with HPLC. Furthermore, the usage of HPTLC stead of HPLC could save environmental resources since no or few sample pre-treatments such as solid phase extraction or liquid-liquid extraction are required when compared with HPLC. Additionally, HPTLC is well suited to quantify several organic compound and profiling of their impurities as it could perfectly handle "dirty" samples without pre-treatment such that both polar and non-polar impurities can be detected even if sitting on the eluent front. The presented contribution is dedicated to spot the light on the opportunities existing for HPTLC as a promising sustainable alternative to HPLC in drugs' analysis and impurity profiling purposes. A model mixture containing Ebastine (EBS) and Phenylephrine hydrochloride (PHE), marketed as Ebast DC® tablets, was utilized in the study. Firstly, an HPTLC-method was developed and then validated for the simultaneous analysis and purity assessment of the named two drugs. Consequently, the obtained results were then compared with those of a previously reported HPLC-method from a green chemistry perspective. • HPTLC is a promising sustainable alternative to HPLC in drugs' analysis and impurity profiling purposes • The first HPTLC-method developed for the simultaneous analysis of Ebastine and phenylephrine HCl. • HPTLC and green analytical chemistry (GAC) could be two sides of an ecofriendly coin. • HPTLC-densitometric method represents an advantageous green method for determination of EBS and PHE in presence of their common impurities. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Impurity profiling in pilot-scale batches of preclinical anticancer candidate, IIIM-290. • Identification, isolation/synthesis and characterization of process-related impurities. • Analytical method validation by HPLC. Abstract IIIM-290, an orally bioavailable preclinical candidate is effective in human xenograft models of leukemia, colon and pancreatic cancer. The promising preclinical data of this lead candidate has shown its potential for clinical development. As a part of its preclinical development, impurity profiling of pilot scale batches is one of the most important component of the CMC documentation. Herein, we report impurity profiling, its quantification in different scale-up batches and analytical method validation. Three impurities ranging from 0.09 to 1.25% in preclinical anticancer candidate, IIIM-290 were detected by validated HPLC method. The impurities (Imp-A , Imp-B and Imp-F) were isolated from the partially purified batch of IIIM-290 using semi-preparative HPLC. Isolated impurities were characterized by 1H, 13C NMR, FTIR and ESI–MS spectral data. Based on the characterization data, the sources of these impurities were identified as unreacted starting material (Imp-A), impurity from botanical raw material (Imp-B ; impurity carried from starting material) and the chemically transformed product (Imp-F) of Imp-B , respectively. [ABSTRACT FROM AUTHOR]

Purpose: Impurity profiling of seized illicit methamphetamine (MA) provides information on MA manufacturing methods in clandestine laboratories, and this drug intelligence supports formulation of strategies to control MA abuse. In the present study, we developed a simultaneous chiral analysis method for MA and its precursors using supercritical fluid chromatography-tandem mass spectrometry equipped with an enantioselective stationary phase.Methods: Chromatographic conditions were optimized by systematic investigation of the flow rate, temperature, back pressure, co-solvent, additive, and mobile phase composition. The ability of the developed method was evaluated using standard and authentic illicit MA.Results: The use of a chiral selector in the stationary phase allowed for simultaneous chiral differentiation of MA and its precursors including ephedrine, norephedrine, chloropseudoephedrine, methylephedrine, dimethylamphetamine, and amphetamine. Sufficient limit of detection, repeatability of retention time, and linearity were achieved. A switching valve interfacing a chromatograph and a mass spectrometer enabled analyzing large amounts of MA directly. The application to the authentic illicit MA samples was achieved and revealed the existence of impurities, which was not detected by conventional gas chromatography-mass spectrometry.Conclusions: The developed supercritical fluid chromatography-tandem mass spectrometry method could be a powerful analytical tool for MA impurity profiling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Orbitrap and SIRIUS were combined for impurity identification. • Isotope score and fragment tree were used for chemical structure elucidation. • Eighteen impurities were identified in thiacloprid. Comprehensive impurity identification in agrochemicals is one key prerequisite for their safety evaluation and certified reference material development. Thiacloprid (THI), belonging to the first generation of neonicotinoids, has been among the most frequently used and detected insecticides. Herein, a novel protocol was developed for the impurity profiling of THI with liquid chromatography-high resolution mass spectrometry (orbitrap) and de novo identification tool (SIRIUS). With MS and MS/MS spectra, the calculated SIRIUS, isotope, fragment tree, and Zodiac scores were used to rank the chemical structure candidates. THI, the main component, was taken as a reference for chemical structure elucidation of impurities by the shared neutral loss and fragmented ions. Finally, 18 impurities were all elucidated and divided into five groups according to their structural difference and 14 impurities were reported for the first time without CAS number. Two impurities were verified with standards by retention time and UV spectrum. This work showed the success of combining de novo identification tool with human intelligence in impurity profiling of THI. [ABSTRACT FROM AUTHOR]

The organic impurity profile of 3,4-methylenedioxyamphetamine (MDA) synthesised from helional via the "twodogs" method was examined to identify route-specific and condition-specific impurities. The synthesis used a condensation reaction, followed by a Beckmann rearrangement, then Hofmann rearrangement, and then conversion to a hydrochloride salt. Two chlorinating agents were investigated for the Hofmann rearrangement reaction, trichloroisocyanuric acid (TCCA) and sodium hypochlorite. Three route-specific impurities were identified in MDA using TCCA, and two of these impurities were condition-specific such that the impurities that formed were dependent on the alcohol used as solvent. Three additional impurities were identified as non-route-specific as they have previously been identified in MDA synthesised from 3,4-methylenedioxycinnamic acid or piperonal. These non-route-specific impurities were also identified in MDA synthesised using sodium hypochlorite. No impurities were detected in MDA hydrochloride. This study identified route- and condition-specific organic impurities in MDA synthesised via the "twodogs" synthetic route using helional as starting material. The results in this study provide further understanding into the illicit synthesis of MDA and highlight the expanding nature of precursors used for illicit drug manufacture. It provides valuable information to decision makers to enact legislative measures and restrict precursors of concern. [ABSTRACT FROM AUTHOR]

A newly developed single quad mass spectrometry (MS) detector was coupled to a ultra-high performance liquid chromatography (UPLC) system and implemented in the routine quality control (QC) and impurity analysis of four therapeutic peptides, namely bleomycin sulfate, tyrothricin, vancomycin HCl and bacitracin, which were selected given their multi-component drug nature and their closely structurally related impurity profiles. The QC and impurity profiling results obtained using the ultra-high performance liquid chromatography ultraviolet/mass spectrometry (UPLC-UV/MS) detection system were analyzed against the results obtained using traditional high performance liquid chromatography-ultraviolet detection (HPLC-UV) methods derived from pharmacopoeial methods. In general, the used stationary phases of sub-2 µm particle (UPLC) technology resulted in lower limits of detection and higher resolution separations, which resulted in more detected impurities and shorter overall run times contrasting the traditional HPLC columns. Moreover, online coupling with a single quad MS detector allowed direct peak identification of the main compounds as well as small impurities, hereby increasing the information content without the need of reference standards.

Advances in biotechnology and the chemical synthesis of peptides have made biopharmaceuticals and synthetic peptide drugs viable pharmaceutical compounds today and an important source for tomorrow's drugs and therapies. Unfortunately, also falsifications and counterfeit versions of these powerful and promising drugs are offered illegally via the internet. Since these falsified preparations are produced outside the legally required quality systems, end-users have no guarantee regarding the efficacy and safety of these products. Although falsified samples of biotherapeutics were already analysed, looking at a specific aspect of their quality or identity, no systematic studies have been performed regarding the presence of different impurities or possible contaminations. Therefore, in order to obtain a better understanding of the potential health risks related to the usage of falsified polypeptide drugs we performed a systematic screening of the ten most frequently encountered falsified peptide drugs on the Belgian market acquired from three different suspected illegal internet pharmacies. The screening incorporated the analysis of the active pharmaceutical ingredient (API), API-related impurities, small molecule contaminants (defined as organic small molecules not belonging to the other categories), elemental impurities and residual solvents. This comprehensive study showed that these type of falsified drugs not only have a high variation in amount of drugs per unit and a low purity (ranging between 5% and 75% for cysteine containing peptides), but also contained the known toxic class one elemental impurities arsenic (As) and lead (Pb). One sample was contaminated with Pb while multiple samples were found with concentrations up to ten times the ICH toxicity limit for parenteral drugs. Subsequent speciation of As confirmed the elevated concentrations for As and demonstrated that all As was present in the more toxic inorganic form. Together with the (sometimes) high amount of peptide impurities and the inherent dangers associated with the use of unauthorized peptide drugs (such as doping peptides or preclinical drugs) this study confirms the reported potential health risks patients/users take when resorting to falsified peptide drugs. Moreover, the presence of the carcinogen As and the known accumulation in human tissues of Pb raises questions about potential sub-acute to chronic toxicity due to the long term administration of these falsified peptide drugs. [ABSTRACT FROM AUTHOR]

Chemical attribution signatures (CAS) associated with different synthetic routes used for the production of Russian VX (VR) were identified. The goal of the study was to retrospectively determine the production method employed for an unknown VR sample. Six different production methods were evaluated, carefully chosen to include established synthetic routes used in the past for large scale production of the agent, routes involving general phosphorus-sulfur chemistry pathways leading to the agent, and routes whose main characteristic is their innate simplicity in execution. Two laboratories worked in parallel and synthesized a total of 37 batches of VR via the six synthetic routes following predefined synthesis protocols. The chemical composition of impurities and byproducts in each route was analyzed by GC/MS-EI and 49 potential CAS were recognized as important markers in distinguishing these routes using Principal Component Analysis (PCA). The 49 potential CAS included expected species based on knowledge of reaction conditions and pathways but also several novel compounds that were fully identified and characterized by a combined analysis that included MS-CI, MS-EI and HR-MS. The CAS profiles of the calibration set were then analyzed using partial least squares discriminant analysis (PLS-DA) and a cross validated model was constructed. The model allowed the correct classification of an external test set without any misclassifications, demonstrating the utility of this methodology for attributing VR samples to a particular production method. This work is part one of a three-part series in this Forensic VSI issue of a Sweden-United States collaborative effort towards the understanding of the CAS of VR in diverse batches and matrices. This part focuses on the CAS in synthesized batches of crude VR and in the following two parts of the series the influence of food matrices on the CAS profiles are investigated. [ABSTRACT FROM AUTHOR]

Impurity profiling has been used as a useful tool for analyzing nearly every drug class currently known on the illicit market. Impurities present within seized samples have the potential to determine source of origin, route of synthesis used, as well as provide a useful clue into the potential reaction mechanisms that are present for each synthetic procedure. Perhaps the most well studied of these impurity profiles exists for methamphetamine, including information to more than one route of synthesis. Within the present study, a complete synthesis of methamphetamine was performed, including a reductive amination of phenylpropanone (P2P) using methylamine hydrochloride and sodium triacetoxyborohydride (STAB) rather than the conventional aluminum mercury amalgam commonly found in the literature. During the analysis of the final product from this reaction, a major impurity within the reaction, bis(1-phenylpropan-2-yl)amine (m/z 253), was detected by GC-MS as well as direct-infusion ESI-MS. This impurity has been previously reported as a Leuckart route-specific impurity. Its detection within the reductive amination of P2P points towards the use of impure methylamine hydrochloride containing some traces of acid, and provides further insight into the reductive amination of P2P. In both the Leuckart reaction and this reductive amination via STAB, the presence of acid and ammonia leads to this impurity. [ABSTRACT FROM AUTHOR]

Abstract: The analysis of organic impurities plays an important role in the impurity profiling of methamphetamine, which in turn provides valuable information about methamphetamine manufacturing, in particular its synthetic route, chemicals, and precursors used. Ultra‐high‐performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) is ideally suited for this purpose due to its excellent sensitivity, selectivity, and wide linear range in multiple reaction monitoring (MRM) mode. In this study, a dilute‐and‐shoot UHPLC–MS/MS method was developed for the simultaneous identification and quantitation of 23 organic manufacturing impurities in illicit methamphetamine. The developed method was validated in terms of stability, limit of detection (LOD), lower limit of quantification (LLOQ), accuracy, and precision. More than 100 illicitly prepared methamphetamine samples were analyzed. Due to its ability to detect ephedrine/pseudoephedrine and its high sensitivity for critical target markers (eg, chloro‐pseudoephedrine, N‐cyclohexylamphetamine, and compounds B and P), more impurities and precursor/pre‐precursors were identified and quantified versus the current procedure by gas chromatography–mass spectrometry (GC–MS). Consequently, more samples could be classified by their synthetic routes. However, the UHPLC–MS/MS method has difficulty in detecting neutral and untargeted emerging manufacturing impurities and can therefore only serve as a complement to the current method. Despite this deficiency, the quantitative information acquired by the presented UHPLC–MS/MS methodology increased the sample discrimination power, thereby enhancing the capacity of methamphetamine profiling program (MPP) to conduct sample‐sample comparisons. [ABSTRACT FROM AUTHOR]

Abstract: α‐Phenylacetoacetonitrile (APAAN) is one of the most important pre‐precursors for amphetamine production in recent years. This assumption is based on seizure data but there is little analytical data available showing how much amphetamine really originated from APAAN. In this study, several syntheses of amphetamine following the Leuckart route were performed starting from different organic compounds including APAAN. The organic phases were analysed using gas chromatography–mass spectrometry (GC–MS) to search for signals caused by possible APAAN markers. Three compounds were discovered, isolated, and based on the performed syntheses it was found that they are highly specific for the use of APAAN. Using mass spectra, high resolution MS and nuclear magnetic resonance (NMR) data the compounds were characterised and identified as 2‐phenyl‐2‐butenenitrile, 3‐amino‐2‐phenyl‐2‐butenenitrile, and 4‐amino‐6‐methyl‐5‐phenylpyrimidine. To investigate their significance, they were searched in data from seized amphetamine samples to determine to what extent they were present in illicitly produced amphetamine. Data of more than 580 cases from amphetamine profiling databases in Germany and the Netherlands were used for this purpose. These databases allowed analysis of the yearly occurrence of the markers going back to 2009. The markers revealed a trend that was in agreement with seizure reports and reflected an increasing use of APAAN from 2010 on. This paper presents experimental proof that APAAN is indeed the most important pre‐precursor of amphetamine in recent years. It also illustrates how important it is to look for new ways to identify current trends in drug production since such trends can change within a few years. [ABSTRACT FROM AUTHOR]

A HPLC-UV-CAD method with a HILIC column for impurity profiling of the 99mTc chelating agent bicisate has been developed and evaluated. Bicisate and its impurities were separated by means of isocratic elution on a zwitterionic stationary phase using a mixture of 7.5 mmol/L trifluoroacetic acid and acetonitrile (47.5:52.5 V/V) as the mobile phase. Five different bicisate batches of a manufacturer were tested using the method. In addition LC–MS experiments were conducted in order to identify the impurities. The predominant impurities found were the oxidation product (disulfide), the monoester of ethylene dicysteine and an unknown compound with an m/z of 293 in ESI positive mode. A new degradation product of bicisate, bicisate lactam, was identified during sample solution stability assessment. [ABSTRACT FROM AUTHOR]

Comprehensive on-line two-dimensional liquid chromatography (LCxLC) is expected to generate impressive peak capacities, which makes it a method of choice for the analysis of complex samples such as pharmaceuticals. A comparative study of different sets of chromatographic conditions including stationary phase, pH additive and organic modifier was carried out with two real pharmaceutical samples in order to find out the best analytical conditions for implementation of one or several generic on-line LCxLC separations. Our choice was based on the evaluation of both degree of orthogonality and practical sample peak capacity under linear gradient conditions. The potential of 190 combinations of chromatographic systems was compared. A set of 3 RPLCxRPLC configurations was found to be very attractive for both samples and in good agreement with the findings of a previous study carried out with 17 model compounds, thereby supporting the idea of using generic LCxLC conditions in the pharmaceutical area. The three selected 2D-systems were implemented for the on-line RPLCxRPLC-UV/MS analysis of two pharmaceutical samples. It was shown, for each sample, that these 2D-systems were able to generate an effective peak capacity close to 1000 in less than 50 min. For each sample, baseline separation was obtained for every known compound and furthermore a large number of unknown impurities could also be separated and identified. Finally, in the proposed conditions, the total number of compounds detected was significantly improved from one RPLC separation to one RPLCxRPLC separation. Only a small additional gain was observed by performing a second RPLCxRPLC separation or even a third one. [ABSTRACT FROM AUTHOR]

We report a new High Performance Liquid Chromatography-Mass Spectrometry (HPLC–MS) method to rapidly detect and quantify meglumine by-products (specifically reducing sugar(s) and nitrogen impurities) that could be present in the meglumine samples. Meglumine is a secondary amine obtained from glucose and it is an excipient used as counter-ion in several pharmaceutical formulations, especially when the concentration of the active pharmaceutical ingredient (API) is so high that the sodium is not a suitable option. Moreover, the increased use of meglumine is related to its ability to improve solubility in aqueous solutions due to the presence of a large number of hydroxyl groups. Thus, even if meglumine is widely used as excipient in pharmaceutical formulations, its impurity profile has never been fully evaluated. Here, we propose the use of a commercial agent that specifically reacts with carbonyl compounds, 1-(4-aminobenzyl)-1,2,4-triazole, with the aim of improving the detection of reducing sugars, such as glucose, after an easy derivatization procedure. Finally, we describe the method validation and the analysis of the impurity profile of meglumine samples from different manufacturers. [ABSTRACT FROM AUTHOR]

The development of new active pharmaceutical ingredients (API) requires accurate impurity profiling. Nowadays, reversed-phase HPLC (RPLC) on C18 stationary phase is the method of first choice for this task and usually employed in generic screening methods. However, this method sometimes fails, especially when the target analyte is not sufficiently retained, making impurity analysis difficult or even impossible. In such cases, a second method must be available. In the present paper, we compare the merits of RPLC on C18 phase to those of previously optimized alternative methods, based on the analysis of a large and diverse set of small-molecule drug candidates. Various strategies are considered: RPLC on C18 phase but with different mobile phase composition (acidic or basic), RPLC with a pentafluorophenyl stationary phase, or mixed-mode HPLC with both bimodal and trimodal stationary phases. First, method performances were compared in terms of response rate (proportion of compounds eluted) and peak shapes for a large set of synthetic drugs (140) with structural diversity and their orthogonality was evaluated. Then a subset of compounds (25) containing varied impurity profiles was used to compare the methods based on the capability to detect impurities and evaluate the relative purity of the API. [ABSTRACT FROM AUTHOR]

To achieve the most complete impurity profiling of synthetic drugs with a single chromatographic technique, high resolution is required, which may be gained with a combination of high efficiency and versatile selectivity, allowing to separate most similar analytes. Compared to a single-column chromatographic method, coupling complementary stationary phases promises both an increase in efficiency and an increase in selectivity possibilities. With supercritical fluid chromatography (SFC), the use of long columns is facilitated by the low viscosity of the mobile phase. In this paper, we investigate the interest of coupling two achiral stationary phases (Acquity UPC 2 HSS C18 SB and Nucleoshell HILIC) that were previously observed to have excellent complementarity in SFC to carry out impurity profiling on 25 individual drug substances containing varied numbers and amounts of impurities. The single-column gradient methods are compared to tandem-column gradient methods with the two possible ordering of columns (C18 phase in first or second position) based on selectivity, peak capacity, sensitivity, UV-estimated purity of the active pharmaceutical ingredient and number of impurities detected with UV-estimated concentration >0.04%. It appears that it could be more beneficial to have two columns coupled in a single analysis than two consecutive methods with the single columns. The overall analysis time are nearly the same, but with more informative chromatograms in about 35% cases. [ABSTRACT FROM AUTHOR]

Separation of morphine and its impurities (related substances specified in relevant European Pharmacopoeia monographs, as well as the other naturally occurring coextracted alkaloids) was obtained within a close retention window on a reverse phase HPLC column, eluted with optimized gradient, consisting of methanol and 5 mM ammonium formate, adjusted to pH 10.2. Systematic optimization of the chromatographic conditions was carried out using design of experiments. According to their mass spectra, known and specified impurities were identified and tentative structures for unknown impurities were proposed. MS analyses were performed in positive ionization mode using heated electrospray ionization. Fragmentation patterns of the eluted compounds under optimized mass spectrometry conditions indicated that all detected impurities are structurally related to morphine. [ABSTRACT FROM AUTHOR]

Macrolides are multicomponent drugs whose impurity control is always a challenge demanding analysis method with good sensitivity and selectivity. Three separate, sensitive, accurate liquid chromatography tandem mass spectrometry methods (LC–MS) were developed for the measurement of three 16-membered ring macrolides (josamycin, josamycin propionate and midecamycin acetate) and related substances in commercial samples. The characteristics of impurities in macrolides were summarized as useful guidance for the impurity analysis of this class of drugs. For each drug, a large number of unknown components have been detected with the high-sensitive MS detector and possible structures of the majority of them were postulated based on the summarized fragmentation rules of 16-membered ring macrolides. A QSRR model was constructed by multilinear regression to predict the retention times of identified impurities which were not detected by the LC–MS methods, without obtaining their reference standards. Satisfactory performance was obtained during leave-one-out cross-validation with a predictive ability ( Q 2 ) of 0.95. The generalisation ability of the model was further confirmed by an average error of 2.3% in external prediction. The best QSRR model, based on eight molecular descriptors, exhibited a promising predictive performance and robustness. [ABSTRACT FROM AUTHOR]

This review describes the recent trends in analytical perspectives of impurity profiling and forced degradation of pharmaceutical drug and drug products used for the treatment of hypertension. Hypertension classes include diuretics, angiotensin receptor blocker, β adrenergic blocker, calcium channel blocker. Description based on use of various chromatographic methods, stationary phase, column, detectors are mentioned. Recent advancement in the field of impurity and stability study are focused on drugs belonging to these categories. [ABSTRACT FROM AUTHOR]

For the first time, a comprehensive investigation of the impurity profile of the synthetic thyroid API (active pharmaceutical ingredient) liothyronine sodium (LT 3 Na) was performed by using reversed phase HPLC and advanced structural elucidation techniques including high resolution tandem mass spectrometry (HRMS/MS) and on-line hydrogen-deuterium (H/D) exchange. Overall, 39 compounds were characterized and 25 of these related substances were previously unknown to literature. The impurity classification system recently developed for the closely related API levothyroxine sodium (LT 4 Na) could be applied to the newly characterized liothyronine sodium impurities resulting in a wholistic thyroid API impurity classification system. Furthermore, the mass-spectrometric CID-fragmentation of specific related substances was discussed and rationalized by detailed fragmentation pathways. Moreover, the UV/Vis absorption characteristics of the API and selected impurities were investigated to corroborate chemical structure assignments derived from MS data. [ABSTRACT FROM AUTHOR]

Pyrimethamine is an important antiparasitic drug in the treatment of malaria and toxoplasmosis and is often used in combination with either sulfadoxine, sulfalene, or sulfadiazine. Determining the content of pyrimethamine and investigating the related substances is currently possible applying either a compendial monograph utilizing thin layer chromatography as well as liquid chromatographic methods used by the respective manufacturers. To provide a simple method which is capable of determining the content of pyrimethamine and of resolving four of its potential synthetic impurities a very simple, cheap, precise, and accurate isocratic RP-HPLC method was developed. All analytes can be separated within a total runtime of 30 min and the method was linear within the concentration ranges of 0.12-0.740, 0.104-0.621, 0.120-0.710, 2.0-11.8, and 1.01-5.80 µg mL for pyrimethamine, impurity A, impurity B, impurity C, and impurity D, respectively. These substances were separated by employing a Eurospher-II CH column (250 × 4.6 mm, 5 µm particle size), a mobile phase being a mixture of a 0.05 M KHPO buffer solution (pH 2.6) and methanol in the ratio 40:60 (v/v). The analysis was carried out at 30 °C, applying a flow rate of 1.2 mL min, and a detection wavelength of λ = 215 nm. The coefficients of determinations ( R ) for the five analytes were greater than 0.994 for pyrimethamine and all impurities. Results of recovery studies were within the range of 89.1-105.1% for all substances. In all tested genuine batches of pyrimethamine raw material impurities within the specified limits were present which is concurrent with results obtained from using the present manufacturer's method. [ABSTRACT FROM AUTHOR]

Developing a robust analytical HPLC–UV method to characterize a drug candidate during an early stage of development is a major challenge when not all impurity standards are available. Here, we report our efforts to devise an efficient strategy for HPLC method development using continuous screening of analytical parameters without impurity standards. This strategy uses small incremental changes in the mobile phase pH and column temperature to trace each impurity on an overlay chromatogram. We tested this method using benzocaine as the active pharmaceutical ingredient (API), and compounds with similar structures to represent unknown impurities. Despite the coelution of peaks, results identified the number of impurities and indicated the starting point and parameter variables of the ensuing optimization step. Further, we demonstrated that the retention time of each peak as a function of mobile phase pH accounts for the apparent pKaof known and unknown compounds in the presence of an organic solvent. This information is critically important to the selection of a robust pH range for HPLC methods. [ABSTRACT FROM AUTHOR]

The volatile chemical constituents in complex mixtures can be analyzed using gas chromatography with mass spectrometry. This analysis allows the tentative identification of diverse impurities of an illicit methamphetamine sample. The acquired two-dimensional data of liquid-liquid extraction was resolved by multivariate curve resolution alternating curve resolution to elucidate the embedded peaks effectively. This is the first report on the application of a curve resolution approach for chromatogram fingerprinting to identify particularly the embedded impurities of a drug of abuse. Indeed, the strong and broad peak of methamphetamine makes identifying the underlying peaks problematic and even impossible. Mathematical separation instead of conventional chromatographic approaches was performed in a way that trace components embedded in methamphetamine peak were successfully resolved. Comprehensive analysis of the chromatogram, using multivariate curve resolution, resulted in elution profiles and mass spectra for each pure compound. Impurities such as benzaldehyde, benzyl alcohol, benzene, propenyl methyl ketone, benzyl methyl ketone, amphetamine, N-benzyl-2-methylaziridine, phenethylamine, N, N,α-trimethylamine, phenethylamine, N,α,α-trimethylmethamphetamine, N-acetylmethamphetamine, N-formylmethamphetamine, and other chemicals were identified. A route-specific impurity, N-benzyl-2-methylaziridine, indicating a synthesis route based on ephedrine/pseudoephedrine was identified. Moreover, this is the first report on the detection of impurities such as phenethylamine, N,α,α-trimethylamine (a structurally related impurity), and clonitazene (as an adulterant) in an illicit methamphetamine sample. [ABSTRACT FROM AUTHOR]

In this study, an experimental design matrix was created and executed to test the effects of various real-world factors on the ability of (1) the accelerated diffusion sampler with solid phase micro-extraction (ADS-SPME) and (2) solvent extraction to capture organic chemical attribution signatures (CAS) from dimethyl methylphosphonate (DMMP) spiked onto painted wall board (PWB) surfaces. The DMMP CAS organic impurities sampled by ADS-SPME and solvent extraction were analyzed by gas chromatography/mass spectrometry (GC/MS). The number of detected DMMP CAS impurities and their respective GC/MS peak areas were determined as a function of DMMP stock, DMMP spiked volume, exposure time, SPME sampling time, and ADS headspace pressure. Based on the statistical analysis of experimental results, several general conclusions are made: (1) the amount of CAS impurity detected using ADS-SPME and GC/MS was most influenced by spiked volume, stock, and ADS headspace pressure, (2) reduced ADS headspace pressure increased the amount of detected CAS impurity, as measured by GC/MS peak area, by up to a factor of 1.7–1.9 compared to ADS at ambient headspace pressure, (3) the ADS had no measurable effect on the number of detected DMMP impurities, that is, ADS (with and without reduced pressure) had no practical effect on the DMMP impurity profile collected from spiked PWB, and (4) solvent extraction out performed ADS-SPME in terms of consistently capturing all or most of the targeted DMMP impurities from spiked PWB. [ABSTRACT FROM AUTHOR]