Trace determination of mutagenic alkyl toluenesulfonate impurities via derivatization headspace–GC/MS in an active pharmaceutical ingredient of a candidate drug

Determination of residual alkyl iodides and alkyl bromides as their corresponding alkyl chlorides in drug substances by headspace GC-FID

Primary and secondary alkyl iodides and primary alkyl bromides were quickly and conveniently converted into their corresponding alkyl chlorides via SN2 halide-halide substitution. The resultant alkyl chlorides simultaneously demonstrated increased volatility and stability paired with standard headspace GC-FID methodology. The derivatization was performed on both standard and sample alike and occurred during the headspace oven equilibration phase, eliminating the extra reaction step traditionally performed during many derivatization analyses. Reaction times, temperatures, and completeness of conversion were studied as well as response from common headspace solvents and application of various chloride sources. Recovery of iodomethane from four challenging substrates was studied from the trace level to approximately 1000 ppm. Recovery ranged 94-110 % from verapamil hydrochloride (2.5-1007 ppm), 95-102 % from methylnaltrexone bromide (26-1054 ppm), and 92-106 % from (S)-laudanosine (49-942 ppm). Using hydrogen chloride as the chloride source, a method for determination of residual iodomethane in (S)-N-methyl-laudanosine iodide was validated over a 0.5-24.9 μg/mL range with a 0.1 μg/mL detection limit, 91-103 % accuracy, and 3.2 % relative standard deviation.

Preparation and optimization of dummy molecularly imprinted polymer-based solid-phase extraction system for selective enrichment of p-toluene sulfonate esters genotoxic impurities

Sulfonate esters, one class of genotoxic impurities (GTIs), have gained significant attention in recent years due to their potential to cause genetic mutations and cancer. In the current study, we employed the dummy template molecular imprinting technology with a dummy template molecule replacing the target molecule to establish a pretreatment method for samples containing p-toluene sulfonate esters. Through computer simulation and ultraviolet-visible spectroscopy analysis, the optimal functional monomer acrylamide and polymerization solvent chloroform were selected. Subsequently, a dummy template molecularly imprinted polymer (DMIP) was prepared by the precipitation polymerization method, and the polymer was characterized in morphology, particle size, and composition. The results of the adsorption and enrichment study demonstrated that the DMIP has high adsorption capability (Q = 7.88 mg/g) and favorable imprinting effects (IF = 1.37); Further, it could simultaneously adsorb three p-toluene sulfonate esters. The optimal adsorption conditions were obtained by conditional optimization of solid-phase extraction (SPE). A pH 7 solution was selected as the loading condition, the methanol/1 % phosphoric acid solution (20:80, v/v) was selected as the washing solution, and acetonitrile containing 10 % acetic acid in 6 mL was selected as the elution solvent. Finally, we determined methyl p-toluene sulfonate alkyl esters, ethyl p-toluene sulfonate alkyl esters, and isopropyl p-toluene sulfonate alkyl esters in tosufloxacin toluene sulfonate and capecitabine at the 10 ppm level (relative to 1 mg/mL active pharmaceutical ingredient (API) samples) by using DMIP-based SPE coupled with HPLC. This approach facilitated the selective enrichment of p-toluene sulfonate esters GTIs from complex API samples.

Time-dependent selected reaction monitoring-based GC-MS/MS method for estimation of genotoxic impurities in new antibacterial agent: alalevonadifloxacin mesylate

Alalevonadifloxacin mesylate (ALA), pro-drug of levonadifloxacin is a new antibiotic approved in India to treat infections caused by Gram-positive bacteria. Alkyl mesylates (AMs) are known genotoxic impurities (GTI’s) formed in drug substances isolated as mesylate salts. Time-dependent selected reaction monitoring (t-SRM)-based gas chromatography tandem mass spectrometry (GC-MS/MS) method has been developed for trace estimation of AMs, namely, methyl methane sulfonate (MMS), ethyl methane sulfonate (EMS) and isopropyl methane sulfonate (IMS) in ALA. Liquid-liquid extraction (LLE) procedure using dichloromethane (DCM) as an extracting solvent was employed to extract AMs from the drug substance. Automatic selective reaction monitoring (auto-SRM) tool was applied to identify the most intense SRM pair of the ions to achieve the highest sensitivity. The method was validated in terms of specificity, linearity, sensitivity, precision, and accuracy. The limit of quantitation (LOQ) for the MMS, EMS and IMS were 5, 10, and 20 ng/g of ALA, respectively. For all analytes, the correlation coefficient (R) were greater than 0.9975 in the concentration range of 3.0–260 ng/mL. Mean recovery of all analytes was in the range of 91.77 to 97.65%.