Unknown residual solvents identification in drug products by headspace solid phase microextraction gas chromatography-mass spectrometry

Summary A sensitive headspace SPME method for the extraction of residual solvents from pharmaceutical products has been developed and optimized. It was found that minimizing sample and headspace volume has a beneficial effect on extraction efficiency. At the same time the method reproducibility was seriously affected by reducing sample and headspace volume. The added air volume was not found to have any significant influence on method sensitivity. The method showed reproducibilities of less than 10% and detection limits as low as 1 ppb for benzene and dichloromethane. The headspace SPME method is around 1000 times more sensitive than static headspace. The optimized parameters were headspace volume 1.5 mL, sample volume 10 μL, and extraction time 30 min. The method was successfully applied to the identification of unknown residual solvents in three different proprietary active drug substances and was successfully applied to the confirmation of the presence of benzene in a proprietary drug substance. Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001     

Application of the solvation parameter model in method development for analysis of residual solvents in pharmaceuticals

The solvation parameter model was applied in the development of a method for the analysis of residual solvents in pharmaceuticals. The interactions between organic solvents and six different stationary phases were studied using gas chromatography. The retention times of the organic solvents on these columns could be predicted under isothermal or temperature-programmed conditions using the established solvation parameter models. The predicted retention times helped in column selection and in optimizing chromatographic conditions during method development, and will form the basis for the development of a computer-aided method.     

Ruggedness testing of gas chromatographic method for residual solvents in pharmaceutical substances

Summary Ruggedness testing is performed on a gas chromatographic method for the quantitative determination of residual solvents in steroids. Eight experimental variables or factors which were expected to influence the quantitative results were selected. These factors were divided into two independent groups, i.e. four factors related to the injection process and four factors related to separation and detection. In order to determine interaction between factors and quadratic effects, a central composite design was selected for the set-up of the experiments. Because in the method an internal standard is used, relative peak area was used as response. A deviation of up to 2.5% per factor for the quantitative results was regarded as acceptable. Other responses studied are related to the system suitability. Observed main, quadratic and interaction effects were translated into rugged intervals of the experimental variables by graphical presentation. It was found that besides main effects significant interaction effects were present, for example between the temperature of the injector and the split-flow. Interaction effects can easily result in the reduction of the rugged intervals by a factor of 2. The calculated rugged intervals were compared with the precision of the instrument or factor settings in order to estimate the ruggedness of the factors. Eventually, the maximum effect of the variation in the instrument settings on the quantitative results regarding the precision of the factor settings was found to be only 2.2%. Overall, the method proved to be rugged for most factors, except for the split-flow of the injector for which the method was only rugged to a limited extent.     

Quantification of residual solvents in antibody drug conjugates using gas chromatography

The detection and quantification of residual solvents present in clinical and commercial pharmaceutical products is necessary from both patient safety and regulatory perspectives. Head-space gas chromatography is routinely used for quantitation of residual solvents for small molecule APIs produced through synthetic processes; however residual solvent analysis is generally not needed for protein based pharmaceuticals produced through cultured cell lines where solvents are not introduced. In contrast, antibody drug conjugates and other protein conjugates where a drug or other molecule is covalently bound to a protein typically use solvents such as N,N-dimethylacetamide (DMA), N,N?dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or propylene glycol (PG) to dissolve the hydrophobic small molecule drug for conjugation to the protein. The levels of the solvent remaining following the conjugation step are therefore important to patient safety as these parental drug products are introduced directly into the patients bloodstream. We have developed a rapid sample preparation followed by a gas chromatography separation for the detection and quantification of several solvents typically used in these conjugation reactions. This generic method has been validated and can be easily implemented for use in quality control testing for clinical or commercial bioconjugated products.     

Fast capillary GC using a low thermal mass column oven for the determination of residual solvents in pharmaceuticals

A low thermal mass column oven was used for fast capillary GC analysis (high throughput) of residual solvents in pharmaceutical products. A dedicated capillary column, 20 m L x 180 microm ID x 1 microm DB-624 was programmed from 35 degrees C (30 s) to 150 degrees C at 100 degrees C/min and to 250 degrees C (30 s) at 200 degrees C/min, resulting in a total GC cycle time of less than 4 min. Complete separation of a target 20-component mixture was achieved, while method performance in terms of repeatability, sensitivity, and linearity was maintained in comparison to the generic method currently applied in our laboratories.     

Multiple headspace single-drop microextraction coupled with gas chromatography for direct determination of residual solvents in solid drug product

This paper proposed a multiple headspace single-drop microextraction (MHS-SDME) method coupled to gas chromatography with flame-ionization detection (GC-FID) for direct determination of residual solvents in solid drug product. The MHS-SDME technique is based on extrapolation to an exhaustive extraction of consecutive extractions from the same sample which eliminates the matrix effect on the quantitative analysis of solid samples. The total peak area of analyte is calculated with a beta constant which can be obtained from the slope of the linear regression that related to the peak area of each extraction and the number of extraction times. In this work, a model drug powder was chosen and the amounts of residues of two solvents, methanol and ethanol, were investigated. The factors influencing the extraction process including extraction solvent, microdrop volume, extraction time, sample amount, thermostatting temperature and incubation time were studied. 10 mg of drug powder was incubated for 3 h at 140 °C prior to the first extraction and thermostatted for 15 min at 140 °C between each extraction. Extraction was carried out with 2 μL of dimethyl sulfoxide (DMSO) as the microdrop for 5 min. The features of the method were established using standard solutions. Validation of the proposed method showed good agreement with the traditional dissolution method for analysis of residual solvents in drug product. The results indicated that MHS-SDME has a great potential for the quantitative determination of residual solvents directly from the solid drug products due to its low cost, ease of operation, sensitivity, reliability and environmental protection.     

Dispersive liquid-liquid microextraction combined with gas chromatography for extraction and determination of class 1 residual solvents in pharmaceuticals

The present study reports a new method for analyzing class 1 residual solvents (RSs), 1,1-dichloroethene (1,1-DCE), 1,2-dichloroethane (1,2-DCE), 1,1,1-trichloroethane (1,1,1-TCE), carbon tetrachloride (CT), and benzene (Bz), in pharmaceutical products using dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography-flame ionization detection (GC-FID). Unlike common DLLME methods, solvents of high boiling point were selected as dispersive and extraction solvents in order to prevent their chromatographic peaks from overlapping with those of analytes that have short retention times. Therefore N,N-dimethyl formamide (DMF) and 1,2-dibromoethane (1,2-DBE) were chosen as dispersive and extraction solvents, respectively. Analytical parameters of the proposed method were determined and good linearities and broad linear ranges (LRs) were obtained. Taking 500 mg samples, limit of detections for the tested pharmaceuticals were obtained as 0.11, 0.03, 0.05, 0.05, and 0.006 μg g(-1) for CT, 1,1-DCE, 1,2-DCE, 1,1,1-TCE, and Bz, respectively, which are considerably much lower than their permissible limits in pharmaceuticals.     

顶空固相微萃取-气相色谱法测定油脂中浸出油溶剂残留的方法研究

采用新型溶胶 凝胶富勒烯涂层的固相微萃取(SPME)探头,建立了顶空固相微萃取 气相色谱法(HS SPME GC)测定食用植物油中溶剂残留主要成分正己烷的方法,并对萃取条件进行了优化,方法的检出限为1.47μg kg(S N=5),RSD=1.9%(n=7),加标回收率为88.4%～102.1%。     

A generic static headspace gas chromatography method for determination of residual solvents in drug substance

In order to increase productivity of drug analysis in the pharmaceutical industry, an efficient and sensitive generic static headspace gas chromatography (HSGC) method was successfully developed and validated for the determination of 44 classes 2 and 3 solvents of International Conference of Harmonization (ICH) guideline Q3C, as residual solvents in drug substance. In order to increase the method sensitivity and efficiency in sample equilibration, dimethylsulfoxide (DMSO) was selected as the sample diluent based on its high capacity of dissolving drug substance, stability and high boiling point. The HS sample equilibration temperature and equilibration time are assessed in ranges of 125–150 °C and 8–15 min, respectively. The results indicate that the residual solvents in 200 mg of drug substance can be equilibrated efficiently in HS sampler at 140 °C for 10 min. The GC parameters, e.g. sample split ratio, carrier flow rate and oven temperature gradient are manipulated to enhance the method sensitivity and separation efficiency. The two-stage gradient GC run from 35 to 240 °C, using an Agilent DB-624 capillary column (30 m long, 0.32 mm I.D., 1.8 μm film thickness), is suitable to determine 44 ICH classes 2 and 3 solvents in 30 min. The method validation results indicate that the method is accurate, precise, linear and sensitive for solvents assessed. The recoveries of most of these solvents from four drug substances are greater than 80% within the method determination ranges. However, this method is not suitable for the 10 remaining ICH classes 2 and 3 solvents, because they are too polar (e.g. formic acid and acidic acid), or have boiling points higher than 150 °C, (e.g. anisol and cumene). In comparison with the previous published methods, this method has a much shorter sample equilibration time, a better separation for many solvents, a higher sensitivity and a broader concentration range.     

顶空毛细管气相色谱法测定茶多酚中有机溶剂的残留量

建立了顶空毛细管气相色谱法测定茶多酚中正己烷、氯仿、乙酸乙酯和丙酮4种有机溶剂残留量的方法.并讨论了平衡温度、平衡时间、盐效应对测定的影响.分析结果表明:该方法对上述4种有机溶剂均达到了完全分离,相关系数为0.994～0.999,检出限范围为0.065～0.268 μg/g,测定结果的相对标准偏差为0.39%～2.13%,样品的回收率为90.9%～105.3%.     

Extraction and preconcentration of residual solvents in pharmaceuticals using dynamic headspace–liquid phase microextraction and their determination by gas chromatography–flame ionization detection

The present study describes a microextraction and determination method for analyzing residual solvents in pharmaceutical products using dynamic headspace–liquid phase microextraction technique followed by gas chromatography–flame ionization detection. In this method dimethyl sulfoxide (μL level) placed into a GC liner‐shaped extraction vessel is used as a collection/extraction solvent. Then the liner is exposed to the headspace of a vial containing the sample solution. The effect of different parameters influencing the microextraction procedure including collection/extraction solvent type and its volume, ionic strength, extraction time, extraction temperature and concentration of NaOH solution used in dissolving the studied pharmaceuticals are investigated and optimized. Under the optimum extraction conditions, the method showed wide linear ranges between 0.5 and 5000 mg L⁻¹. The other analytical parameters were obtained in the following ranges: enrichment factors 240–327, extraction recoveries 72–98% and limits of detection 0.1–0.8 mg L⁻¹ in solution and 0.6–3.2 μg g⁻¹ in solid. Relative standard deviations for the extraction of 100 mg L⁻¹ of each analyte were obtained in the ranges of 4–7 and 5–8% for intra ‐ day (n = 6) and inter ‐ day (n = 4) respectively. Finally the target analytes were determined in different samples such as erythromycin, azithromycin, cefalexin, amoxicillin and co‐amoxiclav by the proposed method.     

The full evaporation technique: a promising alternative for residual solvents analysis in solid samples

The static headspace technique is the most common approach to residual solvent analysis in pharmaceutical and environmental matrices. This paper presents an alternative tool where the volatile impurities are released from the matrix by working directly on a small amount of sample at a high equilibration temperature: the so-called Full Evaporation Technique (FET). The capability of this method was evaluated on a mixture of nine solvents, which belong to Class 3 in the classification of the European Pharmacopoeia Agency for residual solvents, at various levels of concentration: ethanol, acetone, 2-propanol, methyl acetate, 2-butanone, ethyl acetate, tetrahydrofuran, 2-methyl-1-propanol, 1-butanol. Data on linearity, accuracy, precision and sensitivity are reported. Use of an internal standard proved to be necessary when using such a method. The method is then successfully applied to the analysis of solvent traces in permethylated beta-cyclodextrin.     

Residual solvents determination in drug products by static headspace-gas chromatography

Summary Two static headspace selective methods for residual solvents belonging to Class I, II and III have been developed, optimized and validated for drug products, which are insoluble in water. The methods give very good sensitivities (detection limits under 10 ppm) and precision (under 5.5% RSD) for all solvents. The detection limit for benzene was 0.1 ppm, in concordance with Pharmacopoeia requirements. During method optimization we found that sample volume and water content have a critical influence on the sensitivity. From our data, it is beneficial to choose low sample volume. If sample solubility in the organic solvent allows it, the optimum sample volume is between 0.1 and 0.3 mL. For drug products with water content greater than 7%, the increase in sensitivity produced by water presence should be taken into consideration, otherwise inconsistent recovery data and underestimation of residual solvent content will happen. The headspace vial volume has a critical influence on system precision. Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001     

Mixed aqueous solutions as dilution media in the determination of residual solvents by static headspace gas chromatography

Static headspace (HS) sampling has been commonly used to test for volatile organic chemicals, usually referred to as residual solvents (RS) in pharmaceuticals. If the sample is not soluble in water, organic solvents are used. However, these seriously reduce the sensitivity in the determination of some RS. Here, mixed aqueous dilution media (a mixture of water and an organic solvent like dimethyl formamide, dimethyl sulfoxide or dimethyl acetamide) were studied as alternative media for static HS-gas chromatographic analysis. Although it has been known that mixed aqueous dilution media can often improve sensitivity for many RS, this study used a systematic approach to investigate phase volumes and the organic content in the HS sampling media. Reference solutions using 18 different class 1, 2 and 3 RS were evaluated. The effect of salt addition was also studied in this work. A significant increase in the peak area was observed for all RS using mixed aqueous dilution media, when compared with organic solvents alone. Matrix effects related to the mixed aqueous dilution media were also investigated and reported. Repeatability and linearity obtained with mixed aqueous dilution media were found to be similar to those observed with pure organic solvents.     

Proton transfer reaction of a new orthohydroxy Schiff base in protic solvents at room temperature

Ground and excited state inter- and intramolecular proton transfer reactions of a new o-hydroxy Schiff base, 7-ethylsalicylidenebenzylamine (ESBA) have been investigated by means of absorption, emission and nanosecond spectroscopy in different protic solvents at room temperature and 77 K. The excited state intramolecular proton transfer (ESIPT) is evidenced by a large Stokes shifted emission (approximately 11000 cm(-1)) at a selected excited energy in alcoholic solvents. Spectral characteristics obtained reveal that ESBA exists in more than one structural form in most of the protic solvents, both in the ground and excited states. From the nanosecond measurements and quantum yield of fluorescence we have estimated the decay rate constants, which are mainly represented by nonradiative decay rates. At 77 K the fluorescence spectra are found to be contaminated with phosphorescence spectra in glycerol and ethylene glycol. It is shown that the fluorescence intensity and nature of the species present are dependent upon the excitation energy.     

顶空气相色谱-质谱法同时测定蜂蜜中57种挥发性有机溶剂残留

建立了顶空气相色谱-质谱(HS-GC/MS)同时测定蜂蜜中57种挥发性有机溶剂(包括烷烃类、芳香烃类、醇类、酮类、酯类、醚类)残留量的分析方法。蜂蜜样品在密封的顶空瓶中用水溶解后,在顶空仪中于80 ℃下平衡30 min,使气-液两相达到动态平衡。采用DB-624毛细管色谱柱(60 m×0.25 mm×1.40 μm)对57种有机溶剂进行分离,GC/MS测定,外标法定量。该方法对于烷烃类、芳香烃类和醚类挥发性有机溶剂在0.005～0.2 μg、酯类0.05～2.0 μg、酮类0.5～20 μg、醇类2.5～100 μg范围内线性关系良好,相关系数均大于0.996。对于烷烃类、芳香烃类和醚类挥发性有机溶剂在1.0～20 μg/kg、酯类10～200 μg/kg、酮类100～2000 μg/kg、醇类500～10000 μg/kg添加范围内的平均添加回收率为61.0%～113.1%,相对标准偏差为1.9%～9.8%。对于烷烃类、芳香烃类和醚类挥发性有机溶剂的检出限为1.0 μg/kg、酯类10 μg/kg、酮类100 μg/kg、醇类500 μg/kg。该方法操作简单、快速,灵敏度和准确度高,适用于蜂蜜样品中多种挥发性有机溶剂残留量的同时检测。     

Determination of residual solvents and reagents in X-ray contrast media by automatic static headspace capillary gas chromatography

A specific, sensitive, and simple method for the quantitation of residual methanol, 2-propanol, 2-butanol, 2-methoxy-1-ethanol, 1-chloro-3-methoxy-2-propanol, 3-chloro-2-methoxy-1-propanol, and 1,3-dimethoxy-2-propanol in two non-ionic X-ray contrast media, has been developed. The headspace of a 25 % w/V aqueous solution of contrast media, obtained at 90–110°C in 15 min, was injected onto a capillary column coated with cyanopropyl, phenyl, dimethylpolysiloxane polymer. The internal standards used were 2-pentanol and 3-methoxy-1-butanol. The limits of detection were below 5 μg/g. The repeatability of the method at 50 μg/g of each solvent was below 5 %; and at 100 μg/g of the methoxypropanol compounds and 2-methoxy-1-ethanol, below 10 % (RSD, N = 5).     

Analysis of organic solvents in printing inks by headspace gas chromatography – mass spectrometry

Static headspace analysis by gas chromatography has been found to be a suitable method for the analysis of organic solvents in printing inks. Experimental conditions for the analysis have been optimized, and the accuracy and relative standard deviation of the method has been determined. The solvent content of 29 printing inks has been measured.     

AMicro-sized headspace GC technique for determination of organic volatile impurities in water-insoluble pharmaceuticals

Summary A micro-sized headspace technique is presented for determination of organic volatile impurities (OVIs) in water-insoluble pharmaceuticals. Its main features include reduction of the amounts of sample of drug and sample dissolution medium, from 100–200 mg and 1–5 mL, respectively, in the traditional headspace method to 5–30 mg and 100 μL in the micro-sized headspace method, and shortening the headspace equilibration time from 45–60 min to 5–10 min. The validity of method has been examined both experimentally and theoretically. The relative standard deviation of the analysis and the linearity of method satisfied the requirements of the United States Pharmacopoeia. It was found that headspace equilibrium conditions have little influence on the sensitivity of the method, and that the presence of different amounts of drug substance in the sampling solution has little effect on the analytical results, in contrast with the traditional headspace GC method.     

气相色谱—傅里叶变换红外光谱联用技术用于分析工业丙酮中的杂质

本文提出了一种气相色谱－傅里叶变换红外光谱联用技术分析工业丙酮杂质成份的方法，该方法采用ＦＦＡＰ毛细管柱，柱长２５ｍ，内径０．２５ｍｍ，膜厚０．３３μｍ，占总面积１．１６％的１２种杂能够被分离和鉴定。