Method development on automated sample preparation system for content uniformity and assay testing in a product with multiple APIs and new strategy for quick development and application.

Automation of analytical sample preparation and testing is always attractive due to its high efficiency and continuous operation, but it can also be very challenging due to the operational complexity and method development. Studies focused on method development in automated systems are extremely rare and little has been published on the subject. In this paper, we investigate several unique and advanced aspects of this subject.

Assay of active pharmaceutical ingredients in drug products based on relative response factors: Instrumentation insights and practical considerations.

Relative Response Factors (RRFs) can be used for quantitation of one compound against another and it is widely used for Impurity analysis of pharmaceutical products; however, the application in potency assay is limited. Through an extensive study shown in this paper, it can be concluded that using the "RRF methodology" for potency assay is much more challenging compared to impurity analysis, due to the much tighter criteria required for potency analysis. The effects of instrument settings, which are rarely discussed or recognized in current HPLC analytical method development and quality release testing, are discussed.

Determination of individual homologues and total content of benzalkonium chloride by reversed-phase high-performance liquid chromatography using a short butyl column.

Benzalkonium chloride (a mixture of alkylbenzyldimethylammonium chlorides that usually contains C-10, C-12, C-14, and C-16 homologues), commonly known as BKC, is used as a bacteriostatic agent in many household, food, and drug products. In this paper, we report a simple, rapid, robust, and stability-indicating reversed-phase HPLC method using a short butyl (C4) column for the simultaneous determination of each individual homologue content, as well as the total concentration of individual homologues in commercial bulk raw material batches of BKC samples. The chromatographic separation was performed on a 5 cm ACE C4 column with mobile phase consisting of water, acetonitrile, and potassium chloride.

Development and validation of a stability-indicating RP-HPLC method for assay of alphamethylepoxide and estimation of its related compounds.

Alphamethylepoxide (16alpha-methyl-Delta1,4-pregnadiene-9beta-11beta-oxide-17alpha,21-diol-3,20-dione) is a key intermediate for the synthesis of various active pharmaceutical ingredients of steroid compounds. A stability-indicating reversed-phase high-performance liquid chromatographic (RP-HPLC) method for the assay of alphamethylepoxide and estimation of its related compounds has been developed and validated. It can accurately quantitate alphamethylepoxide in the presence of numerous structurally related compounds (including the beta-epimer, known as betamethylepoxide).

Development and validation of a stability-indicating RP-HPLC method to separate low levels of dexamethasone and other related compounds from betamethasone.

Betamethasone (BM) is an active pharmaceutical ingredient (API) or an intermediate which is used to manufacture various finished pharmaceutical products. Betamethasone is also used as a starting material to manufacture other APIs that are related to this steroid family. It is quite a challenging task to separate dexamethasone (DM) peak (the alpha epimer) and other structurally related compounds from BM.

Quantitation of trace betamethasone or dexamethasone in dexamethasone or betamethasone active pharmaceutical ingredients by reversed-phase high-performance liquid chromatography.

Adequate separation is essential for the quantitation of trace amounts of dexamethasone that are typically found in betamethasone active pharmaceutical ingredients and vice versa. In this paper, we describe three simple and efficient high-performance liquid chromatography methods from which true baseline separations between betamethasone and dexamethasone are achieved even when the concentration ratios between these two epimers are larger than 2000:1. One method is developed on a 5 cm ACE C8 column that uses water and acetonitrile as the mobile phase and 20 mM beta-cyclodextrin as the mobile phase additive.

Efficient method development strategy for challenging separation of pharmaceutical molecules using advanced chromatographic technologies.

In this paper, we describe a strategy that can be used to efficiently develop a high-performance liquid chromatography (HPLC) separation of challenging pharmaceutical molecules. This strategy involves use of advanced chromatographic technologies, such as a computer-assisted chromatographic method development tool (ChromSword) and an automated column switching system (LC Spiderling). This process significantly enhances the probability of achieving adequate separations and can be a large time saver for bench analytical scientists.

Development and validation of a stability-indicating reversed-phase high performance liquid chromatography method for assay of betamethylepoxide and estimation of its related compounds.

Betamethylepoxide (16beta-methyl-Delta(1,4)-pregnadiene-9beta-11beta-oxide-17alpha,21-diol-3,20-dione) is a key intermediate for the synthesis of various active pharmaceutical ingredients (APIs) of steroid compounds. A stability-indicating reversed-phase HPLC method for assay of betamethylepoxide and estimation of its related compounds has been developed and validated. This method can accurately quantitate betamethylepoxide in the presence of numerous structurally related compounds (including the alpha-epimer, known as alphamethylepoxide).

Enhanced sensitivity electrochemical assay of low-molecular-weight heparins using rotating polyion-sensitive membrane electrodes.

Use of a novel rotating polycation-sensitive polymer membrane electrode yields sensors that can serve as simple potentiometric titration endpoint detectors for the determination of three FDA approved low-molecular-weight heparin (LMWH) anticoagulant drugs (Fragmin, Normiflo, and Lovenox). The rotating electrode configuration dramatically improves the reproducibility and increases the sensitivity for LMWH determinations by protamine titration. At a rotation speed of 3000 rpm, electrodes with optimized thin (50 microm) polymer membranes doped with dinonylnaphthalene sulfonate (DNNS) respond to low levels of protamine (<2 microg mL(-1)) with good precision (+/-1 mV, N=10), when protamine is infused continuously into a Tris-buffer solution, pH 7.