Kattel Krishna, Clogston Jeffrey D.
Nanotechnology Characterization Laboratory, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, MD 21702
Residual solvents are volatile organic chemicals that are used in the synthesis of complex drug products such as nanomedicines and manufacturing/purification of active pharmaceutical ingredients (APIs) and excipients [1]. The key methodology for analysis of residual solvents is gas chromatography (GC) with various sample introduction techniques such as static/dynamic headspace analysis, solid phase microextraction, or direct injection of the analyte into the GC [2]. Dimethyl sulfoxide (DMSO) is a polar aprotic solvent having low vapor pressure and high solubility for organic compounds and hence commonly used as a solvent in headspace-GC. DMSO is known to coelute with other organic solvents such as N-N’-dimethylformamide (DMF), N-N-Dimethylacetamide and benzyl alcohol in HS-GC. However, the headspace technique is not suitable for less volatile analytes such as DMSO as the analyte may not reach the injector and column due to lack of static equilibrium between liquid and gaseous phases. Consequently, the quantitation of high boiling/semi-volatile solvents becomes challenging. In addition, low volatility impacts the method sensitivity. Therefore, direct injection gas chromatography is the preferred method for quantitation of DMSO [3]. This protocol describes the procedure for quantitation of DMSO using direct injection gas chromatography with flame ionization detection (FID). Herein we used a PerkinElmer Clarus 690 GC. Methanol was used as the diluent and an Elite 624 (Crossbond 6% cyanopropyl phenyl 94% dimethylpolysiloxane) 0.32 mm ID x 30 m with 1.8 μm layer capillary column was used for the separation.
残留溶剂是挥发性有机化合物，用于合成纳米药物等复杂药品以及活性药物成分（API）和辅料的制造/纯化[1]。残留溶剂分析的关键方法是气相色谱法（GC），采用各种进样技术，如静态/动态顶空分析、固相微萃取或直接将分析物注入GC[2]。二甲基亚砜（DMSO）是一种极性非质子溶剂，蒸气压低，对有机化合物溶解度高，因此常用于顶空气相色谱法中的溶剂。已知在顶空气相色谱法中，DMSO会与其他有机溶剂如N-N'-二甲基甲酰胺（DMF）、N-N-二甲基乙酰胺和苯甲醇共洗脱。然而，顶空技术不适用于挥发性较低的分析物，如DMSO，因为由于液相和气相之间缺乏静态平衡，分析物可能无法到达进样器和色谱柱。因此，高沸点/半挥发性溶剂的定量变得具有挑战性。此外，低挥发性会影响方法的灵敏度。因此，直接进样气相色谱法是定量DMSO的首选方法[3]。本方案描述了使用带有火焰离子化检测（FID）的直接进样气相色谱法定量DMSO的程序。在此，我们使用了PerkinElmer Clarus 690 GC。甲醇用作稀释剂，使用内径0.32 mm、长度30 m、涂层厚度1.8 μm的Elite 624（交联6%氰丙基苯基94%二甲基聚硅氧烷）毛细管柱进行分离。
