Biomedical subjects

Chunhui Deng

Publications and source records attributed to Chunhui Deng.

At least 37 records · Page 2Linked to original sources

PubMed2005

Rapid determination of C6-aldehydes in tomato plant emission by gas chromatography-mass spectrometry and solid-phase microextraction with on-fiber derivatization.

A simple, rapid, sensitive, and solvent-free method was developed for determination of plant-signalling compounds, the three C6-aldehydes hexanal, (Z)-3-hexenal, and (E)-2-hexenal, in tomato plant emission by gas chromatography-mass spectrometry (GC-MS) and solid-phase microextraction (SPME) with on-fiber derivatization. In this method, O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine (PFBHA) in aqueous solution was first headspace adsorbed onto a 65 microm poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber at 25 degrees C for 5 min, and then the fiber with adsorbed PFBHA was used for headspace extraction of tomato plant emission at 25 degrees C for 6 min. Finally, the resulting oximes adsorbed on the fiber were desorbed and analyzed by GC-MS. Extraction conditions and method validation were studied. The proposed method had low detection limit values for the three aldehydes from 0.1 to 0.5 ng/L and good precision (RSD less than 10%). In this work, the method was applied to investigation of tomato plant defense response to Helicoverpa armigera.

Adsorption↗

PubMed2005

Headspace single-drop microextraction with in-drop derivatization for aldehyde analysis.

A new technique, headspace single-drop microextraction (HS-SDME) with in-drop derivatization, was developed. Its feasibility was demonstrated by analysis of the model compounds, aldehydes in water. A hanging microliter drop of solvent containing the derivatization agent of O-2,3,4,5,6-(pentaflurobenzyl)hydroxylamine hydrochloride (PFBHA) was shown to be an excellent extraction, concentration, and derivatization medium for headspace analysis of aldehydes by GC-MS. Using the microdrop solvent with PFBHA, acetaldehyde, propanal, butanal, hexanal, and heptanal in water were headspace extracted and simultaneously derivatized. The formed oximes in the microdrop were analyzed by GC-MS. HS-SDME and in-drop derivatization parameters (extraction solvent, extraction temperature, extraction time, stirring rate microdrop volume, and the headspace volume) and the method validations (linearity, precision, detection limit, and recovery) were studied. Compared to liquid-liquid extraction and solid-phase microextraction, HS-SDME with in-drop derivatization is a simple, rapid, convenient, and inexpensive sample technique.

Journal Article↗

PubMed2005

Rapid determination of acetone in human blood by derivatization with pentafluorobenzyl hydroxylamine followed by headspace liquid-phase microextraction and gas chromatography/mass spectrometry.

In the current work, a simple, rapid, accurate and inexpensive method was developed for the determination of acetone in human blood. The proposed method is based on derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA), followed by headspace liquid-phase microextraction (HS-LPME) and gas chromatography/mass spectrometry (GC/MS). In the present method, acetone in blood samples was derivatized with PFBHA and acetone oxime formed in several seconds. The formed oxime was enriched by HS-LPME using the organic solvent film (OSF) formed in a microsyringe barrel as extraction interface. Finally, the enriched oxime was analyzed by GC/MS in electron ionization (EI) mode. HS-LPME parameters including solvent, syringe plunger withdrawal rate, sampling volume, and extraction cycle were optimized and the method reproducibility, linearity, recovery and detection limit were studied. The proposed method was applied to determination of acetone in diabetes blood and normal blood. It has been shown that derivatization with HS-LPME and GC/MS is an alternative method for determination of the diabetes biomarker, acetone, in blood samples.

Acetone↗

PubMed2005

Development of microwave-assisted derivatization followed by gas chromatography/mass spectrometry for fast determination of amino acids in neonatal blood samples.

Analysis of amino acids in blood samples is an important tool for the diagnosis of neonatal amino acid metabolism disorders. In the work, a novel, rapid and sensitive method was developed for the determination of amino acids in neonatal blood samples, which was based on microwave-assisted silylation followed by gas chromatography/mass spectrometry (GC/MS). The amino acids were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) under microwave irradiation. The controlled reaction was carried out employing BSTFA under conventional heating at 120 degrees C for 30 min. Experimental results show that microwave irradiation can accelerate the derivatization reaction of amino acids with BSFTA, and much shorten analysis time. The method validations (linear range, detection limit, precision and recovery) were studied. Finally, the method was tested by determination of amino acids in neonatal blood by the measurement of their trimethylsilyl derivatives by GC/MS in electron impact (EI) mode. Two biomarkers of L-phenylalanine and L-tyrosine in phenylketonuria (PKU)-positive blood and control blood were quantitatively analyzed by the proposed method. The results demonstrated that microwave-assisted silylation followed by GC/MS is a rapid, simple and sensitive method for amino acid analysis and is also a potential tool for fast screening of neonatal aminoacidurias.

Amino Acids↗

PubMed2005

Diagnosis of congenital adrenal hyperplasia by rapid determination of 17alpha-hydroxyprogesterone in dried blood spots by gas chromatography/mass spectrometry following microwave-assisted silylation.

17alpha-Hydroxyprogesterone (17OHP) is considered to be the biomarker of congential adrenal hyperplasia (CAH). Screening for CAH in newborns by measuring levels of the biomarker of 17OHP has become routine. In the work, a rapid, simple and sensitive technique was developed for the diagnosis of neonatal CAH by the quantitative analysis of 17OHP in neonatal blood spots. The technique was based on microwave-assisted silylation (MAS) followed by gas chromatography/mass spectrometry (GC/MS). In the method, fast derivatization of 17OHP with N,O-bis(trimethylsilyl)trifluoroacetamide was performed by using microwave irradiation, and the trimethylsilyl derivative thus formed was analyzed by GC/MS. The results of the experiment indicate that MAS followed by GC/MS analysis is a rapid, simple and sensitive method for the determination of 17OHP in blood samples. The proposed technique has been shown to have potential as a powerful tool for the rapid diagnosis of neonatal CAH.

17-alpha-Hydroxyprogesterone↗

PubMed2005

A novel miniaturized flame ionization detector for portable gas chromatography.

A novel miniaturized flame ionization detector (FID) operated by battery, which can be used as a detector in portable gas chromatography (GC) is devised and manufactured. It is characterized by the structure of building blocks, small volume, low energy consumption, and needing only two gases, which can be used for detection of hydrocarbons in portable GC. The miniaturized detector mainly includes a porous metallic diffuser plate, bugle-figuration collector, quartz capillary flame tip, and self-heated system. The miniaturized FID is easy to fabricate and assemble because of its structure of building blocks. The FID response is linear over six orders of magnitude and the detection limit of 0.518 ng for benzene, 0.430 ng for n-dodecane, 0.473 ng for naphthalene, and 0.509 ng for n-tetradecane.

Alkanes↗

PubMed2004

Development of headspace solid-phase microextraction with on-fiber derivatization for determination of hexanal and heptanal in human blood.

Hexanal and heptanal in human blood have been regarded as potential biomarkers of lung cancer. Owing to their high volatilities and activities, it is difficult to accurately measure the two biomarkers. In the current work, headspace solid-phase microextraction (HS-SPME) with on-fiber derivatization technique was developed for quantitative analysis of hexanal and heptanal in human blood. In the proposed method, the two aldehydes in blood were headspace extracted by using a poly (dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber with O-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine (PFBHA) at 60 degrees C for 8 min. The aldehyde oximes formed on the fiber were desorbed and analyzed by gas chromatography-mass spectrometry (GC-MS). The method validations including detection limit, recovery and precision were studied. It was found that the method provided low detection limits of 0.006 nM for hexanal and 0.005 nM for heptanal, recoveries from 89% to 95% and R.S.D. values less than 8.5%. The present method was applied to quantitative analysis of hexanal and heptanal in normal blood and lung cancer blood. Hexanal concentrations from 7.33 to 15.23 microM and heptanal concentrations from 2.47 to 9.23 microM were found in the lung cancer blood, while both hexanal and heptanal in the control blood were lower than 0.6 microM. This further demonstrated that hexanal and heptanal might be the biomarkers of lung cancer. The experimental results showed that GC-MS and HS-SPME with on-fiber derivatization is a simple, rapid, sensitive and solvent-free method for determination of in hexanal and heptanal human blood.

Aldehydes↗

PubMed2004

Rapid determination of essential oil in Acorus tatarinowii Schott. by pressurized hot water extraction followed by solid-phase microextraction and gas chromatography-mass spectrometry.

A simple, rapid, efficient and inexpensive method for the determination of essential oil in a traditional Chinese medicine (TCM), Acorus Tatarinowii Schott. was developed by using pressurized hot water extraction (PHWE) combined with solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). Acorus Tatarinowii Schott. (0.050 g) was subjected to dynamic extraction with water at 50 bar, 150 degrees C and 1.0 ml/min for 5.0 min, and then the essential oil in the aqueous extract were extracted by SPME fibers at 60 degrees C for 10 min, finally the compounds on the fiber were desorbed and analyzed by GC-MS. The PHWE and SPME parameters were studied. The key active compound of alpha-asarone in the TCM samples from three different growing areas was quantitatively analyzed by external standard method. Compared to steam distillation (SD), the proposed method required little time (only 15 min) to prepare sample. Moreover, little sample mass and no organic solvent was needed. The present method provided good repeatability (R.S.D. less than 13.0%) and recovery (92% for alpha-asarone). It has been shown that PHWE-SPME-GC-MS is an alternative method for determination of essential oils in TCMs and a potential tool for TCM quality assessment.

Acorus↗

PubMed2004

Determination of acetone in human breath by gas chromatography-mass spectrometry and solid-phase microextraction with on-fiber derivatization.

Analysis of breath acetone has been used as a diagnostic tool for diabetes. Due to its nature of volatility and activity, it is very difficult to accurately measure the concentration of acetone in human breath by gas chromatography-mass spectrometry (GC-MS). To overcome this problem, we developed a new method using GC-MS and solid-phase microextraction (SPME) with on-fiber derivatization to determine acetone in human breath. Breath gas from controls and diabetic patients was collected in 3-l Tedlar bags. O-2,3,4,5,6-(Pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA) in solution was firstly adsorbed on the SPME fiber of 65 microm polydimethylsiloxane-divinylbenzene (PDMS-DVB), and then the fiber was further headspace exposed in exhaled gas in the Tedlar bag at 40 degrees C for 4 min. Finally, the formed acetone oxime on the fiber was desorbed and analyzed by GC-MS. Using external standard method, acetone in the human breath was quantitatively analyzed by measurement of its oxime. The method provided a low detection limit of 0.049 ppbv for acetone in breath, relative standard deviation (R.S.D.) value of 3.4%, excellent accuracy. In addition, the method required simple sample preparation and no organic solvent. Acetone in diabetic breath was found to be higher than 1.71 ppmv, while its concentration in normal breath was lower than 0.76 ppmv. The results show that GC-MS and SPME with on-fiber derivatization is a simple, rapid and sensitive and solvent-free method for determination of low concentration acetone in breath and analysis of breath acetone can be used as supplementary tool for diagnosis of diabetes.

Acetone↗

PubMed2004

Investigation of volatile biomarkers in lung cancer blood using solid-phase microextraction and capillary gas chromatography-mass spectrometry.

In the present work, solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) was developed for investigation of lung cancer volatile biomarkers. Headspace SPME conditions (fiber coating, extraction temperature and extraction time) and desorption conditions were optimized and applied to determination of volatiles in human blood. To find the biomarkers of lung cancer, investigation of volatile compounds in lung cancer blood and control was performed by using the present method. Concentrations of hexanal and heptanal in lung cancer blood were found to be much higher than those in control blood. The two molecules of hexanal and heptanal were regarded as biomarkers of lung cancer. By comparison of volatiles in breath and in blood, it is demonstrated that hexanal and heptanal in breath were originated from blood and screening of lung cancer by breath analysis be feasible. These results show that SPME/GC-MS is a simple, rapid and sensitive method very suitable for investigation of volatile disease markers in human blood.

Adult↗

PubMed2004

Quality assessment of Flos Chrysanthemi Indici from different growing areas in China by solid-phase microextraction-gas chromatography-mass spectrometry.

Flos Chrysanthemi Indici is a common traditional Chinese medicine (TCM). In this paper, headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was developed for quality assessment of Flos Chrysanthemi Indici from different growing areas in China. SPME parameters such as extraction fibers, extraction temperature, extraction time and sample mass were investigated to achieve identical results to those obtained by the steam distillation (SD). The selected SPME conditions were as follows: SPME fiber coated with 65-microm PDMS/DVB, extraction temperature of 60 degrees C, extraction time of 30 min and sample mass of 1.0 g. Furthermore, four active compounds (eucalyptol, camphor, borneol and bornyl acetate) presented in the TCM were applied to evaluating the quality of Flos Chrysanthemi Indici from 20 various areas. The quality assessment was successfully performed to compare the similarity value (S) between different sample vector of Flos Chrysanthemi Indici and the standard profile vector (SPV). The results showed that the proposed HS-SPME-GC-MS was an alternative technique for quality assessment of Flos Chrysanthemi Indici samples.

China↗

PubMed2004

Headspace solid-phase microextraction and capillary gas chromatographic-mass spectrometric determination of rivastigmine in canine plasma samples.

A simple, rapid and sensitive method for determination of rivastigmine in plasma samples was developed using headspace solid-phase microextraction (HS-SPME) and gas chromatography with mass spectrometry (GC-MS). The optimum conditions for the SPME procedure were: headspace extraction on a 65-microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber; 0.5 ml of plasma modified with 1.0 ml of sodium hydroxide-sodium carbonate solution (0.7 M:0.5M); extraction temperature of 100 degrees C, with stirring at 2000 rpm for 30 min. The calibration curve showed linearity in the range from 0.2 to 80 ng/ml with regression coefficient corresponding to 0.9965 and coefficient of the variation of the points of the calibration curve lower than 10%. The quantification limit for rivastigmine in plasma was 0.2 ng/ml. The method was applied to determination of rivastigmine in canine plasma samples from animals after a single oral administration.

Animals↗

PubMed2004

Rapid determination of acetone in human plasma by gas chromatography-mass spectrometry and solid-phase microextraction with on-fiber derivatization.

Acetone is an important volatile disease marker. Due to its nature of activity and volatility, it is a difficult task to measure the concentration of acetone in biological samples with accuracy. In this paper, we developed a novel method for determination of trace amount acetone in human plasma by solid-phase microextraction technique with on-fiber derivatization. In this method, the poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber was used and O-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA) was first loaded on the fiber. Acetone in plasma sample was agitated into headspace and extracted by solid-phase microextraction (SPME) fiber and subsequently derivatized with PFBHA on the fiber. Acetone oxime was analyzed by gas chromatography-mass spectrometry (GC-MS). Quantitative analysis of acetone in plasma was carried out by using external standard method. The SPME conditions (extraction temperature and time) and the method validation were studied. The present method was tested by determination of acetone in diabetes plasma and normal plasma. Acetone concentration in diabetes plasma was found to be higher than 1.8mM, while in normal plasma was lower than 0.017 mM. The results show that the present method is a potential tool for diagnosis of diabetes.

Acetone↗

PubMed2004

Application of HS-SPME and GC-MS to characterization of volatile compounds emitted from Osmanthus flowers.

Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was developed for characterization of volatile compounds emitted from two varieties Osmanthus flowers of O. fragrans var. latifolius and O. fragrans var. thunbergii. The SPME parameters were studied, the optimum conditions of a 65 microm carbowax/divinylbenzene (CW/DVB), extraction temperature of 22 degrees C and extraction time of 10 min were obtained and applied to extraction of the volatile emissions. Fourteen compounds released from both varieties of Osmanthus flowers were separated and identified by GC-MS, which mainly included alpha-linalool, beta-linalool, trans-linalool oxide, cis-linalool oxide, alpha-lonone, beta-lonone, capraldehyde and decalactone. By comparing their peak areas, we found that the sums of the fourteen compounds from the two Osmanthus flowers were very close, while the relative contents of individual volatile compounds in the two emissions were very different. The relative content of alpha-linalool and beta-linalool in O. fragrans var. latifolius were 39.46% and 0.51%, while in O. fragrans var. thunbergii were 9.53% and 27.71%. Due to their different relative contents, the two varieties of flower have different fragrances.

Aldehydes↗

PubMed2004

A simple, rapid and sensitive method for determination of aldehydes in human blood by gas chromatography/mass spectrometry and solid-phase microextraction with on-fiber derivatization.

Aldehydes are considered potential markers for enhanced oxidative stress and have been proposed as a diagnostic measure of cancer status. Do to their volatility and activity, it is very difficult to accurately measure aldehydes in human blood. In the present work, gas chromatography/mass spectrometry (GC/MS) and solid-phase microextraction (SPME) with on-fiber derivatization was developed for determination of aldehydes in human blood. O-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) in aqueous solution was first adsorbed by a SPME fiber, and then the aldehydes in blood samples were headspace extracted by the SPME fiber and rapidly derivatized with PFBHA on the SPME fiber. Finally, the oximes formed were desorbed and detected by GC/MS in electron ionization (EI) mode. Validation of the present method was carried out, and the method was applied to quantitative analysis of the aldehydes in lung cancer blood. The results demonstrated that GC/MS and SPME with on-fiber derivatization is a simple, rapid, sensitive and solvent-free method for the determination of aldehydes in human blood.

Aldehydes↗

PubMed2004

Rapid determination of amino acids in neonatal blood samples based on derivatization with isobutyl chloroformate followed by solid-phase microextraction and gas chromatography/mass spectrometry.

The purpose of this study was to develop a simple, rapid and sensitive analytical method for determination of amino acids in neonatal blood samples. The developed method involves the employment of derivatization and a solid-phase microextraction (SPME) technique together with gas chromatography/mass spectrometry (GC/MS). Amino acids in blood samples were derivatized by a mixture of isobutyl chloroformate, methanol and pyridine, and the N(O,S)-alkoxycarbonyl alkyl esters thus formed were headspace extracted by a SPME fiber. Finally, the extracted analytes on the fiber were desorbed and detected by GC/MS in electron impact (EI) mode. L-Valine, L-leucine, L-isoleucine, L-phenylanaline and L-tyrosine in blood samples were quantitatively analyzed by measurement of the corresponding N(O,S)-alkoxycarbonyl alkyl esters using an external standard method. SPME conditions were optimized, and the method was validated. The method was applied to diagnosis of neonatal phenylkenuria (PKU) and maple syrup urine disease (MSUD) by the analyses of five amino acids in blood samples. The results showed that the proposed method is a potentially powerful tool for simultaneous screening for neonatal PKU and MSUD.

Amino Acids↗

PubMed2003

Gas chromatography-mass spectrometry with solid-phase microextraction method for determination of methyl salicylate and other volatile compounds in leaves of Lycopersicon esculentum.

Methyl salicylate (MeSA) in many plants is a important signaling compound, which plays an important role in a pathogen-induced defense response. In this paper, gas chromatography-mass spectrometry (GC-MS) with headspace solid-phase microextraction (HS-SPME) was developed for determination of MeSA and other volatile compounds in leaves of a tomato plant (Lycopersicon esculentum). Tomato leaves were ground under liquid nitrogen and sampled by HS-SPME, with a 100 microm polydimethylsiloxane fiber, and finally analyzed by GC-MS. Eighteen compounds in the leaves of tomato plant infested by tobacco mosaic virus (TMV) were separated and identified, among them MeSA, which was quantitatively analyzed by the standard addition method. MeSA concentrations higher than 2.0 microg g(-1) fresh weight accumulated in leaves of TMV-infested tomato plant as the defense response to TMV. A similar concentration of MeSA in the leaves of MeSA-treated tomato plant was also found. No MeSA in leaves of control tomato plant was detected. These findings suggest that MeSA might be a signaling compound in the tomato plant response to TMV. The present method for determination of MeSA required only simple sample preparation and no organic solvent, and provided an excellent relative standard deviation of less than 5.0% and a low detection limit of 10 ng g(-1) fresh weight for MeSA. These results show that GC-MS-HS-SPME is a simple, rapid and sensitive method for determination of MeSA and other plant-signaling compounds in plant tissues.

Gas Chromatography-Mass Spectrometry↗

PubMed2003

Diagnosis of maple syrup urine disease by determination of L-valine, L-isoleucine, L-leucine and L-phenylalanine in neonatal blood spots by gas chromatography-mass spectrometry.

A novel method was developed for the diagnosis of maple syrup urine disease (MSUD) by the determination of L-valine, L-leucine, L-isoleucine and L-phenylalanine in dried blood spots of newborns by gas chromatography-mass spectrometry (GC-MS). The four amino acids were extracted from blood samples by methanol and derivatized by n-butanol and trifluroacetic anhydride under optimum reaction conditions. The corresponding single derivatives of the four amino acids were obtained under the optimum conditions. Their contents in blood samples were analyzed quantitatively by measurement of their derivatives by GC-MS in selected ion monitoring mode. MSUD can be diagnosed on the basis of the ratio of the total content of L-leucine and L-isoleucine to that of L-phenylalanine. The present method only took a short time to perform and required minimal sample preparation, which provided low detection limits and a relative standard deviation of less than 5.0%. The derivatization reactions of the four amino acids, L-valine, L-isoleucine, L-leucine and L-phenylalanine, with n-butanol and trifluroacetic anhydride were investigated and the optimum reaction conditions, including reaction time and temperature, were obtained and used for the determination of the amino acids in plasma samples.

Gas Chromatography-Mass Spectrometry↗