This manuscript describes dynamic coating of capillaries with poly(L-lysine) (PLL) and silica nanoparticles (SiO 2 NPs) and use of the as-prepared capillaries for the separation of biogenic amines and acids by CE in conjunction with LIF detection. The directions of EOF are controlled by varying the outmost layer of the capillaries with PLL and SiO 2 NPs, respectively. Over the pH range 3.0-5.0, the (PLL-SiO 2 NP) n -PLL capillaries have an EOF toward the anodic end and are more suitable for the separation of acids with respect to speed, while the (PLL-SiO 2 NP) n capillaries have an EOF toward the cathodic end and are more suitable for the separation of biogenic amines regarding speed and sensitivity. The separations of standard solutions containing five amines and two acids by CE with LIF detection using (PLL-SiO 2 NP) 2 -PLL and (PLL-SiO 2 NP) 3 capillaries were accomplished within 10 and 7 min, providing plate numbers of 3.8 and 5.0610 4 plates/m for 5-hydroxytryptamine (5-HT), respectively. The LODs for 5-HT and 5-hydroxyindole-3-acetic acid (5-HIAA) are 32 and 2 nM and 0.2 and 1.5 nM when using the (PLL-SiO 2 NP) 2 -PLL and (PLL-SiO 2 NP) 3 capillaries, respectively. Identification and quantification of 5-HIAA, homovanillic acid, and DL-vanillomandelic acid in urine samples from a male before and after drinking green tea were tested to validate practicality of the present approach. The results show that the (PLLSiO 2 NP) 2 -PLL capillary provides greater resolving power, while the (PLL-SiO 2 NP) 3 capillary provides better sensitivity, higher efficiency, and longer durability for the separation of the amines and acids.

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The presence of impurities, particularly the API-related impurities, i.e., degradation-related impurities (DRIs) and interaction-related impurities (IRIs), may affect the quality, safety, and efficacy of drug products. Since the regulatory requirements and management strategies are required to be established and complied, sources of impurities shall be carefully classified prior to take subsequent steps such as development of analytical methods and acceptance criteria. Current international regulatory requirements for the management of impurities in pharmaceuticals were reviewed. Procedures for the identification of DPIs in pharmaceuticals, i.e., ethyl cysteinate dimer, (R)-N-methyl-3-(2-bromophenoxy)-3-phenylpropanamine, sestamibi, etc., using high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) were studied. Scheme for the establishment of analytical methods and acceptance criteria of process-related impurities (PRIs) and DRIs in accordance with the requirements of International Council for Harmonization (ICH) and algorithm to perform the identification of DPIs by using LC-MS/MS has been proposed. Practice of kinetic study to distinguish PRIs and DRIs, determination of the potential core fragments coupled with a predicted list of relevant transformations for conducting MS/MS scans, applications of stable isotope distribution patterns or natural abundances, practice of mass balance, etc., have been well demonstrated to justify the reliabilities of identification results.

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