Quantification of residual monomer in polylactide by gas chromatographic internal standard method

An analytical method has been developed to quantitatively determine the residual lactide monomer in polylactide (PLA) using an internal standard method of gas chromatography (GC). The experimental results showed that diphenyl ether (DPE) was an appropriate internal standard for quantitative analysis of residual lactide in PLA. PLA and DPE were dissolved in dichloromethane and precipitated in hexane. At the same time, the residual lactide in PLA and DPE as an internal standard were extracted to hexane from the polymer solution. The resulting solution could be directly injected into a GC system. Therefore, the residual lactide was determined quantitatively using an internal standard method of GC. This method is practical for measuring the residual lactide content in PLA. When the lactide content is 5.0%, the relative standard deviation (RSD) of the measurements is 1.7%, while RSD is 6.9% at the low level of 0.4%, which indicates that the method is sufficiently precise.     

气相色谱/质谱测定皮革及其制品中乙二醇醚类有机溶剂的残留量

建立了同时测定皮革及其制品中12种乙二醇醚类有机溶剂残留量的气相色谱/质谱-选择离子监测方法。以乙酸乙酯为萃取溶剂,在45℃下超声萃取皮革及其制品中的乙二醇醚类有机溶剂,萃取液经固相萃取柱净化后进行气相色谱/质谱-选择离子监测法测定,外标法定量。在信噪比（S/N）=3的条件下,乙二醇单乙醚（EGEE）的检出限为0.10 mg/kg,其余11种乙二醇醚类有机溶剂的检出限均小于0.05 mg/kg。在3个加标水平下,该方法的平均加标回收率为81.2%~95.5%,相对标准偏差（RSD）为1.4%~6.6%（n=9）。该方法简便快捷,灵敏度高,检出限远远低于欧盟法规《化学品的注册、评估、授权和限制》（REACH）的限量要求,适用于皮革及其制品中乙二醇醚类有机溶剂残留量的测定,为制定相关检测标准提供了参考。     

Determination of residual monomer in polymer latex by full evaporation headspace gas chromatography

This study demonstrated a full evaporation (FE) headspace gas chromatographic technique for the determination of residual monomer in methyl methacrylate (MMA) polymer latex. A very small amount (approximately 10-30 mg) of latex was added to a sealed headspace sample vial (20 ml). A near-complete monomer mass transfer from both liquid (aqueous phase) and solid phase (polymer particles) to the vapor phase (headspace) is achieved within 5 min at a temperature of 110 degrees C. The method eliminates sample pretreatment procedures such as the solvent extraction. Thus, it avoids the risk of polymer deposition on the GC system caused by a directly injection of extraction solvent in the conventional GC monomer analysis. The present method is simple, rapid, and accurate.     

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.     

Determination of residual monomer in polymer or polymer solution by sealed glass capillary sampling

Summary Residual styrene in polystyrene and free phenol in phenolic plywood adhesive have been determined by sealing samples in glass capillary tubes. To prevent loss of sample the ends of the capillary tubes were sealed with a kind of putty made of anhydrous calcium sulfare, calcium carbonate and a small quantity of phenylmethylsilicone fluid. No volatile compounds were released from this sealing material when the capillary tubes were placed in a quartz vaporising furnace at temperatures up to 300°C.     

Determination of the residual ethanol in hydroalcoholic sealed hard gelatin capsules by static headspace gas chromatography with immiscible binary solvents

Static headspace gas chromatography (HS-GC) with immiscible binary solvents is described to quantitatively determine the residual ethanol used to seal the hard gelatin capsules by liquid encapsulated and microspray sealing (LEMS; cfs 1200, Greenwood, SC, USA). The effects of decane, dodecane, heptane, 0.1 M HCl, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidinone and dimethyl sulfoxide on the method sensitivity are compared. It is observed that the ethanol headspace concentrations can be increased by fourfolds when aliphatic hydrocarbon solvents are added into the aqueous sample solutions in a HS vial. In addition, a mathematic model based on the concentration equilibriums of liquid–liquid and liquid–gas phases is derived to quantitatively describe the ethanol headspace concentrations versus the volumes of the aliphatic hydrocarbon solvents. The proposed model fits well to the experimental data. The impacts of the oven temperatures and vial equilibration times on the ethanol headspace concentrations are also investigated. Furthermore, the potential interferences of the capsule placebo and hard gelatin capsule shells on the selectivity and quantitation of the method are discussed. The linearity is validated from 5 μg/mL to 500 μg/mL. The limit of quantitation is 5 μg/mL. The accuracy is determined to be 100.8 ± 6%. Finally, this method is successfully used to determine the residual ethanol in the sealed capsules of 5 mg and 10 mg developmental Drug A, and 100 mg and 200 mg developmental Drug B.     

Simultaneous determination of three organophosphorus pesticides in different food commodities by gas chromatography with mass spectrometry

A sensitive and selective gas chromatography with mass spectrometry method was developed for the simultaneous determination of three organophosphorus pesticides, namely, chlorpyrifos, malathion, and diazinon in three different food commodities (milk, apples, and drinking water) employing solid‐phase extraction for sample pretreatment. Pesticide extraction from different sample matrices was carried out on Chromabond C₁₈ cartridges using 3.0 mL of methanol and 3.0 mL of a mixture of dichloromethane/acetonitrile (1:1 v/v) as the eluting solvent. Analysis was carried out by gas chromatography coupled with mass spectrometry using selected‐ion monitoring mode. Good linear relationships were obtained in the range of 0.1–50 μg/L for chlorpyrifos, and 0.05–50 μg/L for both malathion and diazinon pesticides. Good repeatability and recoveries were obtained in the range of 78.54–86.73% for three pesticides under the optimized experimental conditions. The limit of detection ranged from 0.02 to 0.03 μg/L, and the limit of quantification ranged from 0.05 to 0.1 μg/L for all three pesticides. Finally, the developed method was successfully applied for the determination of three targeted pesticides in milk, apples, and drinking water samples each in triplicate. No pesticide was found in apple and milk samples, but chlorpyrifos was found in one drinking water sample below the quantification level.     

捕集阱顶空气相色谱/质谱法测定水中的二氯一溴甲烷

建立了捕集阱顶空气相色谱/质谱测定水中二氯一溴甲烷的方法。采用正交实验设计对平衡温度、平衡时间、循环次数3个参数进行了优化,在平衡温度70 ℃、平衡时间20 min、循环次数2次的优化条件下,对水中的二氯一溴甲烷进行测定。结果显示,在0.1～10.0 μg/L范围内,二氯一溴甲烷的质量浓度和峰面积呈良好的线性关系,相关系数为0.9991。方法的检出限(S/N=3)为0.03 μg/L,定量限(S/N=10)为0.1 μg/L,回收率为83.1%～111.3%,相对标准偏差为1.7%～5.2%(n=6)。将该方法应用于水中二氯一溴甲烷的定性定量分析,效果良好。     

凝胶渗透色谱-气相色谱-质谱测定花生中乙草胺的残留量

建立了以凝胶渗透色谱(GPC)净化和气相色谱-质谱(GC-MS)技术快速测定花生中乙草胺残留量的方法.经乙腈提取,共提物中的油脂和色素经GPC去除,目标农药采用GC-MS-SIM方式进行定性和定量分析.方法的回收率90%～120%;相对标准偏差2.5%～10%.方法定量限0.005 μg/g.     

Determination of residual clopidol in chicken muscle by capillary gas chromatography/mass spectrometry

Clopidol was extracted from chicken with acetonitrile, and the extract was evaporated to about 5 mL. The concentrated solution was centrifuged and applied to a glass column filled with basic alumina. The column was eluted with methanol and the methanol was evaporated to dryness. The residue was derivatized with Sylon BFT and analyzed by gas chromatography/mass spectrometry (GC/MS). Mass characteristics of trimethylsilyl derivative of clopidol were interpreted manually. The selected-ion monitoring mode was performed at m/z 191, 248, 263, and 265. A sensitive, reproducible GC/MS method was developed for monitoring residues of clopidol in chickens. All recoveries of the drug from chicken muscle fortified at 1, 10, and 100 ng/g were > 65%, and relative standard deviations were < 15%. The detection limit was about 0.5 ng/g, and the quantitation limit was the lower limit of the standard curve, which was about 1 ng/g.     

Method validation of microcystins in water and tissue by enhanced liquid chromatography tandem mass spectrometry

A liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI–MS/MS) method has been developed and validated to identify and quantify trace levels of cyanotoxins or microcystins (MC) in water, bivalves and fish tissue with enhanced sensitivity and specificity. The method enables confirmation and quantification of six MCs (MC-LA, LF, LR, LW, RR and YR) with a single chromatographic run. The applied chromatography also allows determination of certain MC metabolites (Desmethyl-LR and -RR). By using LC-ESI–MS/MS in multiple reaction monitoring (MRM) mode, the limit of detection and quantitation for the microcystins studied, were determined to be between 0.2 and 1 pg on column (5:1 S/N ratio). These values are below the 2 pg detection limits found in the available literature.     

顶空气相色谱法测定盐酸托莫西汀中有机溶剂残留量的研究

建立了盐酸托莫西汀中有机溶剂残留量的顶空气相色谱分析方法.选用大口径HP-快速GC残留溶剂柱为分离柱,FID为检测器,外标法进行定量,并对顶空平衡温度、平衡时间、供试品溶液的制备方法对残留有机溶剂测定的影响进行了研究.甲醇、乙醚、正己烷、乙酸乙酯、四氢呋喃的线性范围分别为 0.41～8.10 μg/mL(r=0.9999)、0.15～3.00 μg/mL(r=0.9995)、0.20～4.01 μg/mL(r=0.9991)、0.32～6.35 μg/mL(r=0.9999)、0.36～7.11 μg/mL(r=0.9999);平均回收率范围96.30%～105.47%,精密度RSD(n=6)2.1%～3.7%;检出限分别为0.2、0.008、0.003、0.04、0.04 μg/mL.     

Determination of residual solvents in bulk pharmaceuticals by thermal desorption/gas chromatography/mass spectrometry

Thermal desorption (TD) techniques followed by capillary GC/MS were applied for the analysis of residual solvents in bulk pharmaceuticals. Solvents desorbed from samples by heating were cryofocused at the head of a capillary column prior to GC/MS analysis. This method requires a very small amount of sample and no sample pretreatment. Desorption temperature was set at the point about 20 degrees C higher than the melting point of each sample individually. The relative standard deviations of this method tested by performing six consecutive analyses of 8 different samples were 1.1 to 3.1%, and analytical results of residual solvents were in agreement with those obtained by direct injection of N,N-dimethylformamide solution of the samples into the GC. This novel TD/GC/MS method was demonstrated to be very useful for the identification and quantification of residual solvents in bulk pharmaceuticals.     

气相色谱/质谱法测定鱼塘中的痕量硫丹

利用气相色谱/质谱(GC/MS),测定了鱼塘中痕量的硫丹,同时实现了硫丹的定性、定量.样品提取简便、高效,无需净化.用GC/MS的选择离子记录(SIR)方式测定低浓度硫丹的含量.硫丹在0.2～1000.0μg/mL范围内呈线性,该方法的检出限为0.086μg/mL,标准添加1.0、50μg/mL硫丹的回收率为87%、92%,测定的相对标准偏差为6.2%、13.1%.本方法能够满足痕量分析的实际要求.     

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%.     

气相色谱-质谱联用法测定水果中4,6-二硝基邻甲酚

利用气质联用（GC-MS）技术建立了水果中4,6-二硝基邻甲酚（DNOC）的测定方法。以二氯甲烷提取水果样品中DNOC残留,并使用N-（特丁基二甲基硅）-N-甲基三氟乙酰胺对提取DNOC残留进行衍生化,利用GC-MS选择离子模式（SIM）测定残留DNOC衍生化产物,在苹果和梨中DNOC的添加回收率在70％～110％之间,相对标准偏差RSD〈9％（n=10）,方法的检出限为10μg/kg。     

Development and application of methods for determination of residual monomer in dental acrylic resins using high performance liquid chromatography

Two high-performance liquid chromatographic methods for determination of residual monomer in dental acrylic resins are described. Monomers were detected by their UV absorbance at 230 nm, on a Nucleosil C18 (5 microm particle size, 100 A pore size, 15 x 0.46 cm i.d.) column. The separation was performed using acetonitrile-water (55:45 v/v) containing 0.01% triethylamine (TEA) for methyl methacrylate and butyl methacrylate, and acetonitrile-water (60:40 v/v) containing 0.01% TEA for isobutyl methacrylate and 1,6-hexanediol dimethacrylate as mobile phases, at a flow rate of 0.8 mL/min. Good linear relationships were obtained in the concentration range 5.0-80.0 microg/mL for methyl methacrylate, 10.0-160.0 microg/mL for butyl methacrylate, 50.0-500.0 microg/mL for isobutyl methacrylate and 2.5-180.0 microg/mL for 1,6-hexanediol dimethacrylate. Adequate assay for intra- and inter-day precision and accuracy was observed during the validation process. An extraction procedure to remove residual monomer from the acrylic resins was also established. Residual monomer was obtained from broken specimens of acrylic disks using methanol as extraction solvent for 2 h in an ice-bath. The developed methods and the extraction procedure were applied to dental acrylic resins, tested with or without post-polymerization treatments, and proved to be accurate and precise for the determination of residual monomer content of the materials evaluated.     

Determination of endothelin-1 in rats using a high-performance liquid chromatography coupled to electrospray tandem mass spectrometry

A sensitive and specific liquid chromatography tandem mass spectrometry method with electrospray ionization for the determination of endothelin-1 in rat plasma and lung effluents has been developed and validated. Detection was achieved by an Applied Biosystems MDS Sciex API 2000 triple quadrupole mass spectrometer coupled to an Agilent 1100 LC system. The limit of detection and the limit of the quantification of ET-1 in matrix buffer was estimated at 40 pM and 1 nM, respectively. The precision and accuracy for both intra- and inter-day determination of the analyte ranged from 2.5% to 14.7% and from 104.2% to 113.3%, respectively. No significant relative matrix effect was observed. Stability of ET-1 established in a bench-top, autosampler, long-term storage stability as well as freeze/thaw cycles shown no significant degradation products in the samples. The results of the method validation indicated that this method is applicable for the determination of the ET-1 concentration in an effluent from the isolated lung preparation as well as in vivo in plasma samples to evaluate ET-1 as a potential biomarker of the progression of pulmonary endothelial dysfunction and pulmonary hypertension in rats induced by a monocrotaline injection.     

固相萃取-气相色谱-质谱联用法测定水中的硝基苯类有机污染物的分析方法研究

建立了固相萃取、毛细柱气相色谱-质谱、内标标准曲线法使用选择离子(SIM)监测采集数据定量分析水中硝基苯类有机化合物的分析方法.通过对固相萃取柱的选择、固相萃取条件(样品溶液的pH、上样速率、上样体积、洗脱液选择及配比)的优化,得出了最佳实验条件.始漏体积达1.5 L.回收率大于80%.检出限为0.015～0.045 μg/L.RSD在1.1%～5.9%之间.     

Determination of trace elements in residual oil by high-resolution inductively coupled plasma mass spectrometry

An analytical method using high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for rapid simultaneous determination of 20 elements, including Na, Mg, Al, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, and Pb elements, in residual oil was described. The sample was dissolved in HNO₃ by microwave digestion, and then the above 20 elements in the solution were analyzed directly by HR-ICP-MS. Most of the spectral interferences could be avoided by measuring in the high-resolution mode. The matrix effect caused by the sample-digesting solution and corrected by Sc, Rh, and Bi as the internal standard elements was studied in detail. The optimum condition of the determination was also tested and discussed. The result showed that the detection limits of the method were in the range of 0.014 to 11.6 μg L⁻¹; the relative standard deviation was less than 3.8% and recoveries in the samples were in the range of 88.4% to 108.0%. This method can be used to determine the trace elements in residual oil with the features of accurate, rapid, and convenient determination.