[Determination of four trihalomethanes in ship ballast water by gas chromatography-negative chemical ionization-mass spectrometry].

Ship ballast water can control the roll, trim, and draft of the ship, and thus ensuring the balance and stability of the ship in the course of sailing, and playing a vital role in the safe navigation of ships. The annual discharge of ship ballast water is very large in China. About three to five billion cubic meters of ship ballast water is discharged into offshore or inland waters every year. This water contains plankton, pathogens, and their larvae or spores. If not be handled appropriately, this will have a serious impact on the ecological environment of the discharge waters. Ballast water is usually treated by electrolysis before being discharged. Sodium hypochlorite can be generated, which can kill microorganisms; however, the by-products trihalomethanes (THMs) are cytotoxic and biotoxic. Studies have shown that THMs may cause fetal growth retardation, spontaneous abortion, or death. The concentration of THMs in drinking water is closely related to the risk of bladder cancer death. Hence, it is important to establish a method for the determination of THMs in ship ballast water. The four kinds of THMs are chloroform, dichlorobromomethane, chlorodibromomethane, and tribromomethane. At present, ship ballast water is mostly analyzed by gas chromatography (GC) using an electron capture detector (ECD) or by gas chromatography-mass spectrometry (GC-MS). Given the low boiling point of THMs, headspace injection and purge-and-trap can be used. Gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS), was adopted. NCI is a soft ionization technique that shows special response to compounds bearing electronegative elements or groups. THMs contain electronegative chlorine atoms and bromine atoms. Therefore, NCI is a good choice for their analysis. The samples were processed by the headspace injection technique. The NaCl content in 10 mL sample was optimized in headspace injection. The results showed that 3.0 g NaCl was the most suitable dosage. The analytes were separated on a DB-5MS UI capillary-column (30 m×0.25 mm×1.0 µm). The target compounds were quantified by using the external standard method in selected ion monitoring (SIM) mode. The four THMs were not only well separated but also showed a high response at 0.2 µg/L. The four THMs showed good linear relationships in the range of 0.2-50 µg/L, with correlation coefficients≥0.995. The limits of quantification (LOQs, S/N=10) were 0.1-0.2 µg/L, and the average recoveries of the four THMs were 90.3%-106.8% at the three spike levels of 0.2, 0.5, and 2.0 µg/L. The relative standard deviations were 1.4%-6.2%. The LOQs of the THMs in the GB/T 5750.8-2006 Standard Test Method of Drinking Water Organic Matter Index are 0.3-6.0 µg/L. It can be seen that the LOQs of the THMs are greatly reduced in this study. The proposed method is accurate, stable, and reliable, and it can be used for monitoring the four THMs in ship ballast water. The method was applied for the detection of 36 ship ballast water samples. In all cases, the detection rates of tribromomethane, chlorodibromomethane, dichlorobromomethane, and chloroform were 83.3%, 69.4%, 22.2%, and 19.4%, respectively. The detection values of tribromomethane, chlorodibromomethane, dichlorobromomethane, and chloroform were 34.25-221.5 µg/L, 3.52-41.87 µg/L, 1.52-8.56 µg/L, and 0.02-5.46 µg/L, respectively. Based on the analysis of several ship ballast water samples (electrolytic water), it was concluded that the greater the number of bromine atoms in the THMs, the higher are the detection rate and detection value in ship ballast water. Compared to chloroform, tribromomethane is more harmful to living beings. China has acceded to the International Convention on Ship Ballast Water and Sediment Control and Management. There is an urgent need to establish analysis methods with high sensitivity, good stability, and high accuracy in addition to determining standards and regulations for ship ballast water.

Comparative study of headspace and headspace single drop microextraction combined with GC for the determination of methanol in wine.

In this work, headspace single-drop microextraction (HS-SDME) method and headspace (HS) method were developed and compared to determine methanol by gas chromatography with flame ionization detector (GC-FID). Several factors influencing extraction efficiency, such as extraction time, temperature, sample volume, stirring rate and extraction solvent were investigated and the optimal conditions could be obtained using 2.0 µL DMF as extractant, 45 °C as heating temperature, 5 min as extraction time, 6 mL sample volume and 1.5 g KCl as addition of salt. The obtained dynamic range of HS-SDME-GC-FID was from 0.05 to 2 mg·L-1 with the limit of detection (LOD) of 0.001 mg·L-1 and that of HS-GC-FID was from 10.0 to 400.0 mg L-1 with LOD of 0.5 mg·L-1. The relative standard deviations (RSD) of HS-SDME-GC-FID was 1.9% (n = 5, C = 0.005 mg·L-1), 4.8%(n = 5, C = 0.02 mg·L-1) and 3.3%(n = 5, C = 0.1 mg·L-1), then the RSD of HS-GC-FID was 4.4%(n = 5, C = 5 mg·L-1), 5.8%(n = 5, C = 20 mg·L-1) and 4.0%(n = 5, C = 40 mg·L-1). Clearly, compared with HS-GC-FID, HS-SDME-GC-FID possessed lower LOD and better reproducibility and both of them were applied to determine methanol in imported wine and the recoveries for the spiked samples were between 83.99 and 117.24%. Overall, HS-SDME approach was confirmed to be a more sensitive and efficient sample pretreatment method and could separate matrix effectively.

Optimization of Technology of Moslae Herba Processed with Ginger Juice and Analysis of Its Volatile Components by HS-GC-MS / 中国实验方剂学杂志

Objective:To optimize the processing technology of Moslae Herba processed with ginger juice, and to explore the changes of its volatile components in processing process. Method:The volatile components in Moslae Herba, ginger juice and Moslae Herba processed with ginger juice were extracted by steam distillation. Volatile components in these products were analyzed by HS-GC-MS and identified by NIST 11 standard mass spectra library. Gas chromatographic conditions were as following:HP-5MS elastic quartz capillary column(0.25 mm×30 m, 0.25 μm), helium as the carrier gas, flow rate of 1.0 mL·min-1, injector temperature at 250℃, sample quantity of 0.2 μL, split ratio of 50:1, temperature program for initial temperature at 40℃, up to 60℃ with the heating rate at 5℃·min-1, keep 2 min, up to 160℃ with the heating rate at 5℃·min-1, keep 3 min, finally rise to 250℃ with the heating rate at 25℃·min-1, keep it for 2 min and finish, mass spectrometry conditions were as following:electron impact ionization(EI), electron collision energy of 70 eV, ion source temperature at 230℃, the interface temperature at 280℃, quadrupole temperature at 150℃, no delay of solvent, electronic multiplier voltage at 2.188 kV, taking full scan mode, scanning range of m/z 35-550.Taking frying time, solid-liquid ratio and moistening time as factors, orthogonal test was adopted to optimize the processing technology with the comprehensive score of relative contents of thymol and carvacrol, number of volatile components and extracting amount of volatile oil as index. Result:A total of 27 volatile components were detected in Moslae Herba. There were 81 volatile components in Zingiberis Rhizoma Recens. The processed products of orthogonal test(No. 1-9) had 31, 38, 29, 35, 38, 33, 34, 22 and 26 volatile components, respectively. Extracting amount of volatile oil was in the order of Moslae Herba processed with ginger juice > Zingiberis Rhizoma Recens > Moslae Herba. The best processing technology was as following:moistening Moslae Herba with equal volume of ginger juice for 6 h, stir-frying for 8 min. Conclusion:Processing has certain impact on the extracting amount of volatile oil in Moslae Herba and the types of volatile components. This optimized technology is stable and feasible, which can provide experimental data for the quality evaluation of processed products of Moslae Herba, and lay a foundation for clarifying its processing mechanism.

Determination of Residual Solvents in Faeces Bombycis Extract by GC / 中国药师

Objective:To establish a method for the determination of solvent residues in faeces bombycis extract by GC .Meth-ods: A GC-headspace injection method was adopted to detect the residual organic solvents in the extract of faeces bombycis .A DB-5MS (30 m ×0.25 mm ×0.25 μm) quartz capillary column was used as the chromatographic column;nitrogen was used as the carrier gas at a flow rate of 0.6 ml· min-1;the injector temperature was 200℃;the detector was a flame ionization detector( FID) with the temperature of 250℃;the temperature program included two phases:the initial temperature was set at 40℃for 10 min, and then risen to 200℃at a rate of 5℃· min-1 and maintained for 5 min;the equilibrium temperature of headspace was 95℃;the equilibrium time was 30 min;the capillary temperature was 110℃;the injection ring temperature was 125℃.Results:The linear range of acetone , 2, 3-dimethylpentane, 3-methylhexane, heptane, 2,2-dimethylhexane, p-xylene, m-xylene, O-xylene and 2,4,6-collidine was 101-3 034μg· ml-1 , 100-2 995 μg· ml-1 , 107-3 197 μg· ml-1 , 101-3 019 μg· ml-1 , 99-2 962 μg· ml-1 , 45-1 358 μg· ml-1 , 44-1 325μg· ml-1, 47-1 411 μg· ml-1 and 104-3 130 μg· ml-1, respectively, and the average r was all above 0.992.The recovery of the method met the requirement , and the blank solvent showed no interference .Eight samples were all accordance with the requirements after the examination .Conclusion:The headspace injection method for the determination of residual organic solvents in the extract of faeces bombycis is simple and reliable .

Determination of Residual Organic Solvents in Paclitaxel by Capillary GC / 中国药师

Objective:To establish a capillary GC method for the determination of residual organic solvents in paclitaxel. Meth-ods:The standard solution and test solution was respectively injected into an HP-INNOWAX sillica capillary column by headspace in-jection. The chromatograms were recorded with an FID. The injection port and detector temperature was 250℃ and 300℃, respective-ly, the initial column temperature was kept at 35℃ for 5 min, and then was risen to 260℃ at the rate of 25℃/min. Results:The four residual organic solvents could be separated completely. The resolution and sensitivity were acceptable. Conclusion: The method is proved to be simple, rapid, sensitive and reliable, and can be used in the determination of residual organic solvents in paclitaxel.

Determination of Residual Organic Solvents in Letrozole by Headspace Capillary Gas Chromatography / 中国药房

OBJECTIVE: To establish headspace capillary gas chromatography for the content determination of residual solvents in letrozole, such as chloroform, ethanol, acetone, ethyl acetate, DMF and isopropanol. METHODS: Dissolved in dimethyl sulfoxide, chloroform, ethanol, acetone, ethyl acetate, DMF and isopropanol in letrozole were determined by headspace gas chromatography with HP-5 capillary gas chromatography. ECD was applied for chloroform, while FID was applied for the other residual solvents. RESULTS: The liner ranges of chloroform, ethanol, acetone, ethyl acetate, DMF and isopropanol were 1.028～10.28 mg?L-1(r=0.999 9), 94.68～946.8 mg?L-1 (r=0.999 7), 94.64～946.4 mg?L-1(r=0.999 7), 110.64～1 106.4 mg?L-1(r=0.999 7), 15.12～151.2 mg?L-1(r=0.999 6), 116.48～1 164.8 mg?L-1(r=0.999 5), respectively. The average recoveries of the residual organic solvents ranged from 97% to 102%. The detection limits were 20～90 ?g?L-1. The residual levels of the six organic solvents in three batches of samples were all up to the standard stipulated in Chinese Pharmacopeia. CONCLUSIONS: The method is simple, sensitive, accurate and reliable for the content determination of residual organic solvents in letrozole.