DB-5 Capillary Column Research Articles

농산물 중 Fenoxanil 잔류성 시험법 개발

Abstract The aim of this study is to develop residue analysis method for fenoxanil, a MBI (melaninbiosynthesis inhibitor) propionamide fungicide, had mainly been used to control rice blast, and disease ofother crops, fruits, and vegetables by using GLC/NPD and GC/MS. Extraction with acetone and partitionwith n-hexane/dichloromethane (80/20, v/v) were performed from hulled rice, soybean, Kimchi cabbage,green pepper, and apple, then column clean-up with florisil was applied. Mean recoveries were 82.2%-109.1% with less than 7.2% of coefficients of variation and limit of quantitation was set at the concentrationof 0.04 mg/kg from the five agricultural products through the determination by GLC/NPD equipped with DB-5 capillary column and single laboratory validation. As a confirmatory method, GC/MS selected ionmonitoring (SIM) was set from m/z 125.0, 188.9, and 293.0. Developed method is expected to apply thesingle residue analysis of fenoxanil in agricultural products.Key words Fenoxanil, GC-NPD/MS, Single residue

Seasonal variation in phytochemicals of essential oil from Juniperus communis needles in western Himalaya

Essential oil from Juniperus communis needles were examined in three different seasons (spring, rainy and winter) throughout the year for the analysis of yield and chemical composition. Volatiles of the needles were obtained by hydrodistillation process using clevenger type apparatus. The essential oil yield in all the seasons was not significantly changed and was found 0.29% (rainy), 0.3% (winter) and 0.33% (spring). Chemical compositions of the oils were analyzed by GC and GC-MS techniques on DB-5 capillary column resulted in identification of twenty-eight components. Identified components accounted for 91.1–93.1% of the total oils. The major class of compounds identified in present essential oil was monoterpene hydrocarbons (51.9–63.7%) with sabinene (30.1–37.1%) as the major constituent. Other compounds characterized in all the seasons were limonene (11.3–15.7%), 4-terpineol (9.1–10.5%), α-pinene (3.6–7.9%), δ-cadinene (3.7–4.6%), cis-sabinene hydrate (3.6–4.2%), myrcene (2.5–3.1%), α-terpinene (2.3–2.8%) and manool (1.3–2.2%). In this experiment winter was found to be most suitable time for the isolation of sabinene and limonene.

Morphological and Chemoprofile (Liquid Chromatography-mass Spectroscopy and Gas Chromatography-mass Spectroscopy) Comparisons of Cyperus scariosus R. Br and Cyperus rotundus L.

Background:Cyperus scariosus (CS) R.Br and Cyperus rotundus (CR) L. belongs to Cyperaceae family which is well-reputed in the traditional systems of medicine. Although they grow in different agro-climatic conditions, they are often considered to be synonymous with each other.Objective:The present study was aimed to systematically classify both the species CS and CR through their morphological features and chemical profiling using liquid chromatography-mass spectroscopy (LC-MS), gas chromatography-mass spectroscopy (GC-MS) and thin layer chromatography patterns of the rhizome extracts.Materials and Methods:A method (LC-MS analysis) has been developed on Agilent LC-MSD Trap SL mass spectrometer equipped with Waters HR C18 column (3.9 mm × 300 mm, 6 μm) using isocratic elution with acetonitrile and water (70:30% v/v ratio). GC-MS analysis was performed on a Shimadzu GC-MS-QP 2010 equipped with DB-5 capillary column (30 m × 0.25 mm × 0.25 μm).Results:Chemoprofiling of CS and CR using LC-MS and GC-MS suggested that these two are different based on their deferential spectral pattern, however, some of the common peaks were found in both the species. In addition, we also performed the preliminary phytochemical investigation of hexane and chloroform extracts of these species, which led to the isolation of stigmasterol, β-sitosterol and lupeol as major constituents in CS.Conclusion:In summary, we have developed optimal chromatographic conditions (LC-MS and GC-MS) and morphological profiles to classify both the species, that is, CS and CR. Collectively, our analytical results coupled with the morphological data clearly suggested that CS and CR are morphologically different.SUMMARY The huge demand for herbal medicine has put pressure on the supply of natural resources which ultimately results in use of substandard materials or substitution and adulteration. The medicinal plants, Cyperus rotundus L and Cyperus scariosus R.Br which belongs to cyperaceae family and extensively used in the traditional systems of medicine. Although these two species are grown in different soil conditions, Cyperus scariosus R.Br often treated as synonymous of Cyperus rotundus. Thus, the present study was undertaken to classify these two species systematically using the modern analytical techniques as a powerful tools. Further, we also carried out the preliminary phytochemical investigation of hexane and chloroform extracts of cyperus scariosus rhizomes, which resulted in the isolation of three compounds namely Sitosterol, Stigmasterol and Lupeol.

Simultaneous determination of 16 organophosphorous pesticides in vegetables, fruits and tea by gas chromatography coupled with clean-up by mesoporous alumina as solid-phase extraction adsorbent

A gas chromatographic method based on solid-phase extraction was developed for the simultaneous determination of 16 organophosphorous pesticides in vegetables, fruits and tea, including cabbage, lettuce, pumpkin, onion, tomato, turnip, apple, pear and tea. The samples were extracted with ethyl acetate, and clean-up with mesoporous alumina as solid-phase extraction adsorbent. The separation of target compounds was performed on a DB-1701 capillary column, and the quantitative analysis of the organophosphorous pesticides was carried out by gas chromatography with flame photometric detection. The results showed that the calibration curves of the 16 organophosphorous pesticides were linear in the range of 10-2 000 microg/L with good correlation coefficients (R2 > 0.997). The recoveries of the pesticides in different samples at three spiked levels ranged from 83.2% to 103.8% with the relative standard deviations of 2.0%-9.9%. This method has high sensitivity, high accuracy and good repeatability, and can be applied to the determination of the organophosphorus pesticide residues in vegetables, fruits and tea.

Preparation and aroma analysis of Chinese traditional fermented flour paste

Volatile compounds in Chinese fermented flour paste were extracted using simultaneous distillation and extraction (SDE) and analyzed using gas chromatography-mass spectrometry (GC-MS) with DB-5 and DB-WAX capillary columns. A total of 84 volatile compounds were identified, including 8 aldehydes, 19 esters, 14 acids, 17 hydrocarbons, 7 heterocycles, and 19 other trace compounds. The major volatiles included furfural, 5-methyl-2-phenyl-2-hexenal, 4-ethylguaiacol, 2-phenylacetaldehyde, ethyl hexadecanoate, isovaleraldehyde, palmitic acid, and 5-methylfurfural. Aroma compounds were investigated using gas chromatography-olfactometry (GC-O) and aroma extract dilution analysis (AEDA). A total of 27 olfactory regions were exposed and 18 aroma extracts were located. Altogether, 6 aroma compounds identified using GC-O showed higher flavor dilution factors (FD≥32), including isovaleraldehyde, furfural, pentanoic acid, 2-acetylfuran, 1-octen-3-ol, and 2-phenylacetaldehyde. Compared with soybean sauce, fermented flour paste has more esters and aldehydes, which contribute to the desired fruity, caramel, sweet, and roasted odors.

Determination of Deoxynivalenol in Poultry Feed by Three Gas Chromatographic Detection Techniques

Three different gas chromatographic detection techniques were applied for the determination of deoxynivalenol (DON) present in poultry feed samples. Extraction and cleanup procedures were kept the same for GC–FID, GC–ECD and GC–MS methods. Although all three GC methods provided good and comparable results, but more attention was focused on GC–FID due to its lower cost and easy availability in many laboratories. Therefore, a short 15 m DB-1 short column was introduced for the determination of DON in poultry feed to reduce the time of analysis and initial cost of column. An inter-laboratory study for GC–FID was performed in two laboratories using four naturally DONS-contaminated feed samples and one spiked with standard. The relative standard deviations for repeatability (RSDr) and relative standard deviations for reproducibility (RSDR) of naturally contaminated feed were in the range 5–23 and 11–24 %, respectively. The Horwitz Ratio (HORRAT) was less than 1.0 in each sample. From the spiking test, recovery, RSDr, RSDR and value of HORRAT were 93, 5, 11 and 0.6 %, respectively. For GC–FID method, limit of quantification was found to be 6 μg kg−1. Thus, GC–FID method using 15 m DB-1 capillary column is sensitive and validated analytical method for the determination of DON for poultry feed.

Determination of kepone residue in seawater by gas chromatography coupled with electron capture detector

The effects of extraction solvent, capillary column, cleanup method, co-eluted analytes and other influencing factors on the detection of kepone in seawater were investigated. The analytical method of gas chromatography (GC) coupled with electron capture detector (ECD) was established to determine kepone in seawater. In the method, liquid-liquid extraction and sulfuric acid cleanup were used in the sample pre-processing. Chromatographic analysis was performed on a DB-5 capillary column with external standard method. The kepone was extracted from a 1 L seawater sample by 50 mL dichloromethane. Sulfuric acid was used to remove the interference materials co-extracted from the sample. After cleanup, the extract was dissolved in 1% (v/v) methanol/hexane solvent and analyzed by GC-ECD. In the linear range from 5 microg/L to 100 microg/L of kepone, the correlation coefficient was 0.998 9. The average spiked recoveries were 81% - 108% with the relative standard deviations (RSDs) of 1.2% -5.1% (n = 6). The detection limit was 0.6 ng/L. This method shows good extraction efficiency, high sensitivity and good reproducibility, and is suitable for the determination of kepone in seawater.

Determination of multi-pesticides in black tea by subcritical water extraction and gas chromatography-tandem mass spectrometry

A gas chromatography-tandem mass spectrometry (GC-MS/MS) method with subcritical water extraction was developed for the determination of 21 organochlorine and pyrethroid pesticides in black tea. Under the extraction pressure of 5 MPa, the target compounds were extracted with subcritical water at the temperature of 150 degrees C for 15 min, transferred into acetone-n-hexane (1:1, v/v), and cleaned-up by an ENVI-Carb solid phase extraction (SPE) column. The GC separation was performed on a DB-5 capillary column. The pesticides were determined by MS/MS in multiple reaction monitoring (MRM) mode and quantified by matrix-matched internal standard method. The calibration curves showed good linearities in the range of 5.0-320.0 microg/L with the correlation coefficients greater than 0.99. The limit of quantification (S/N > 10) was 50 ng/g, and the limit of detection (S/N > 3) was 10 ng/g. The recoveries of pesticides spiked in the tea at three levels of 50, 100 and 200 ng/g were ranged from 70. 18% to 119.98% with the relative standard deviations (RSDs) of 5.01%-11.76%. The sensitivity, accuracy and precision of the method meet the technical standard of the pesticide determination. The method can be applied to the determination of organochlorine and pyrethroid pesticides in black tea.

Compositions, enantiomer characterization and antifungal activity of two Ocimum essential oils

Essential oil extracted from aerial parts of two Ocimum species (O. canum and O. kilimandscharicum) was investigated using gas chromatography and gas chromatography/mass spectrometry techniques on DB-5 (5% diphenyl-95% dimethylpolysiloxane) and β-cyclodextrin (6-tertiarybutyldimethylsiliyl-2,3-diethyl-β-cyclodextrin) capillary columns. Essential oil extracted from O. canum contained camphor, limonene, camphene and myrtenol as most abundant constituents among monoterpenoids, whereas β-selinene, α-selinene, maaliol and β-caryophyllene were identified under sesquiterpenoids class. On contrary, two folds higher camphor was recorded in O. kilimandscharicum. Maaliol (6.4%) was characterized in O. canum for the first time with the help of extensive 1D and 2D-NMR experiments. Therefore, maaliol can be considered as a marker constituent to differentiate both the camphor rich oils. Further, when the oils were subjected to chiral analysis on β-cyclodextrin column; a high enantiomeric excess for (1R)-(+)-camphor was recorded. This revealed a close relationship between these two species in terms of biosynthesis of single enantiomer. Apart from analysis, oils were assessed for antifungal activity against Rhizoctonia solani and Choanephora cucurbitarum. O. kilimandscharicum exhibited a complete inhibition against R. solani and C. cucurbitarum while O. canum was only effective against R. solani.

Essential oil composition of Reseda lutea from Iran

The genus Reseda is one of the herbs in the Resedaceae family [1]. In Iran, this genus is represented by 10 species, including Reseda lutea L. [1]. R. lutea, known as yellow mignonette or wild mignonette, has economic importance. It has been used as a medicinal plant, in salads, in the carpet and rug industry as a source of natural dye, in animal husbandry as a grazing plant and stock food source, in honey production, in combating erosion, and as a primary succession plant [2, 3]. On the other hand, the species is regarded as a weed in some parts of the world, especially in cultivated areas [4]. Sener et al. also reported that the extract of R. lutea possesses pharmacological activities against insects, brine shrimp, nematodes, and microorganisms [5]. Likewise, Nakhatov et al. isolated some alkaloids from the epigeal parts of R. lutea [6]. In this study, due to its economic importance and wide distribution in Iran, the essential oil composition of R. lutea was investigated for the first time. The essential oil components obtained from the aerial part of R. lutea are listed in Table 1, where the percentage and Kovats indices of the components are given. As shown in Table 1, analysis of the aerial parts oil of R. lutea resulted in the identification of 42 constituents, representing 95.6% of the oil. The main constituents of the oil were benzonitrile (17.9%), (Z)-phytol (13.0%), n-heptacosane (7.5%) -ionone (6.2%), hexahydrofarnesyl acetone (5.1%), and palmitic acid (4.6%). The aerial parts of R. lutea were collected during the flowering stage in the Alamut region, province of Qazvin, Iran, in May 2010. Voucher specimens (No. 8273) have been deposited at the Herbarium of the Research Institute of Forests and Rangelands (TARI), Tehran, Iran. The aerial parts (133.0 g) of the plant were subjected to hydrodistillation using a Clevenger-type apparatus and extracted by diethyl ether for 3 hrs. After decanting, drying over anhydrous sodium sulfate, and evaporating of the solvent, the corresponding yellow colored oil was recovered in a yield of 0.05% w/w. GC-FID analysis was performed on a Shimadzu 15A gas chromatograph equipped with a split/splitless (ratio 1:30) injector (250 C) and a flame ionization detector (250 C). Nitrogen was used as the carrier gas (1 mL/min), together with a DB-5 capillary column (50 m 0.2 mm, film thickness 0.32 m). The column was kept at 60 C for 3 min and then heated to 220 C with a 5 C/min rate and kept constant at 220 C for 5 min. Relative percentage amounts were calculated from the peak area using a Shimadzu C-R4A chromatopac data processor without the use of correction factors. GC-MS analysis was performed using a HewlettPackard 5973 with an HP-5MS column (30 m 0.25 mm, film thickness 0.25 m). The column temperature was kept at 60 C for 3 min and programmed to 220 C at a rate of 5 C/min and kept constant at 220 C for 5 min. The flow rate of helium as carrier gas was 1 mL/min. MS were taken at 70 eV, mass range 30 to 350 amu, and scan time 2 scans/sec. The compounds were identified by comparison of the Kovats indexonan HP-5MS column with those reported in [7] and the NIST library, and by comparison of their mass spectra with either the Wiley library or with published mass spectra [7–9]. The Kovats indices for all the components were determined according to the Van Den Dool method using n-alkanes as standards [10].

Essential oil composition of Anchusa italica from Iran

The family Boraginaceae consists of about 100 genera and 2000 species distributed in the temperate zone, especially in the Mediterranean and tropical regions [1]. Five species of the genus Anchusa (Boraginaceae) are found in Iran [2]. The Borage plants are one of the most important folk medicine plants in Iran. They are of value in treating common cold symptoms, depression and stress, and are anti-inflammatory and antibacterial [3, 4]. Anchusa italica Retz. plants, named “Gav zaban” in Persian, grows in the mountains of some provinces of Iran. The people of that area use the leaves and flowers of A. italica specifically to treat flu symptoms. The anti-influenza activity of alcoholic and aqueous extracts of A. italica has been investigated in a previous report [3]. The findings of this study indicated that A. italica exhibited activity against the influenza virus. In other research, a qualitative phytochemical analysis of 55 Iranian plants, especially A. italica, has been performed for the presence of alkaloids, tannins, saponins, and flavonoids [4]. The results showed the existence of alkaloids, saponins, and flavonoids. The extract of A. italica plant has also been used as an emollient. Likewise, poly[3-(3,4-dihydroxyphenyl)glyceric acid] from A. italica roots has been reported [5]. The lipids and lipophilic components of seeds of three Boraginaceae species, including A. italica, have also been studied [6]. The seed oil of A. italica contains significant quantities of -6 and -3-octadecatrionic acids. In this study, the essential oil composition of A. italica from Iran was investigated for the first time. The essential oil constituents from the aerial part of A. italica are listed in Table 1, in which the percentages and Kovats indices of the components are given. As shown in Table 1, the oil of the aerial parts of A. italica consist of 34 compounds, representing 91.4% of the oil. The main constituents of the oil were diisobutyl phthalate (14.6%), dibutyl phthalate (9.0%), and hexahydrofarnesylacetone (8.1%). The aerial parts of A. italica were collected during the flowering stage in the Alamut region, Province of Qazvin, Iran, in May 2010. Voucher specimens (No. 88274) have been deposited at the Herbarium of the Research Institute of Forests and Rangelands (TARI), Tehran, Iran. The aerial parts (150.0 g) of A. italica were subjected to water distillation using a Clevenger-type apparatus and extracted by diethyl ether for 3 h. After decanting, drying over anhydrous sodium sulfate, and evaporating the solvent, we recovered the corresponding yellowish colored oil in a yield of 0.02% w/w. GC-FID analysis was performed on a Shimadzu 15A gas chromatograph with a split/splitless (ratio 1:30), injector (250 C) and a flame ionization detector (250 C); nitrogen was used as the carrier gas (1 mL/min). A DB-5 capillary column (50 m 0.2 mm, film thickness 0.32 m) was used. The column was kept at 60 C for 3 min, then heated to 220 C with a 5 C/min rate and kept constant at 220 C for 5 min. Relative percentage amounts were calculated from the peak area using a Shimadzu C-R4A chromatopac data processor without the use of correction factors. GC-MS analysis was performed using a Hewlett-Packard 5973 with an HP-5MS column (30 m 0.25 mm, film thickness 0.25 m). The column temperature was kept at 60 C for 3 min and programmed to 220 C at a rate of 5 C/min and kept constant at 220 C for 5 min. The flow rate of helium as carrier gas was 1 mL/min. MS were taken at 70 eV, mass range 30 to 350 amu, and scan time 2 scans/sec.

Analysis of cracking gas compressor fouling by pyrolysis gas chromatography-mass spectrometry

The fouling from the different sections of the cracked gas compressor in Daqing Petrochemical Corporation was analyzed by pyrolysis gas chromatography-mass spectrometry (Py/GC-MS). All the samples were cracked in RJ-1 tube furnace cracker at the cracking temperature of 500 degrees C, and separated with a 60 m DB-1 capillary column. An electron impact ionization (EI) source was used with the ionizing voltage of 70 eV. The results showed the formation of fouling was closely related with cyclopentadiene which accounted for about 50% of the cracking products. Other components detected were 1-butylene, propylene, methane and n-butane. This Py/GC-MS method can be used as an effective approach to analyze the causes of fouling in the petrochemical plants.

Changes in eggshell ultrastructure of Falco naumanni and Tyto alba exposed to pesticides and polychlorinated biphenyls (PCBs)

Changes in the quality of eggs of birds exposed to environmental contaminants have been described, but few reports concern eggshell ultrastructure. In this study, infertile or addled Lesser Kestrels (Falco naumanni) and Barn owls (Tyto alba) eggs were collected from the polluted area of Gela plain (Sicily) during 2007, and compared in terms of organophosphate and organochlorine pesticides, and PCBs levels, and eggshell ultrastructure as determined by scanning electron microscopy. Pesticide and PCB residues in eggs were determined by Gas chromatography/ mass spectrometry (GC/MS) [GC Agilent 7890A/MS Agilent 5975C (Agilent technologies) using a DB-5 capillary column in the selected ion monitoring mode]. The GC/MS analysis revealed that eggs contained measurable amounts of some pesticides and PCBs. There was a low detection of organophosphate pesticides while the most abundant organochlorine residues detected were p,p’ DDT, p,p’ DDE, and Hexachlorobenzene. While, the most abundant PCBs detected congeners were PCB 138, 153, 170, 180, and 187. Although the general structure of the eggshell layers was maintained, the results showed ultrastructural differences in mammillary and palisade eggshell layers between high level and low level contaminated eggs in Tyto alba. Furthermore, mammillary cores of the eggshell had an increased distance between themselves with respect to well organized structures present in uncontaminated egg. In this paper we verify the presence of environmental contaminants in the eggs and document structural changes in bird of prey eggshells. The data could suggest that some contaminants can contribute to reduced reproductive performance (infertile or addled egg) by structural changes in the eggshell. The alteration in morphological disposition of mammillary cores could also suggest an impairment of gas exchange.

Quantitative Analysis of Dimethyl Formamide Residues in Acrylic Fiber by GC

In this article, acrylic fiber which was from factory production lines was chosen as samples. The method consisted of extraction of Diethyl Formamide (DMF) via using solid-liquid extraction technique and Gas Chromatograph (GC) analysis. DMF in acrylic fiber were extracted by distilled water, separated though DB-17 capillary column and detected by Flame Ionization Detector (FID). By means of external standard method quantitative analysis was accurately investigated. Detection limit was 3 ppm and recovery rate of DMF was in the range of 94% and 98%. These results showed that this test method was of high precision and sensitivity, which achieved the enterprise production requirements.

Determination of Dihydroxyacetone and Glycerol in Fermentation Process by GC after n-Methylimidazole Catalyzed Acetylation

A gas chromatographic method that accurately measures glycerol and dihydroxyacetone from a fermentation broth is described in this paper. The method incorporates a sample derivatization reaction using n-methylimidazole as catalyst in the presence of acetic anhydride. Resulting derivatives are separated on a DB-5 capillary column and flame ionization detector. Results show that 10 μL n-methylimidazole and 75 μL acetic anhydride are sufficient to complete the acetylation for glycerol and dihydroxyacetone at room temperature for 5 min. The present method exhibits good linearity at a concentration range of 1-100 g/L with excellent regression (R(2) > 0.9997). The limits of detection are 0.025 and 0.013 g/L for dihydroxyacetone and glycerol, respectively. The method has been successfully applied to the monitoring and control of the fermentation process, and recoveries are in the range of 95.5-98.8% with relative standard deviations below 1%.

Determination of alkyl methanesulfonates in doxazosin mesylate by gas chromatography-mass spectrometer

High sensitive rapid gas chromatography-mass spectrometry method for the determination of four carcinogenic alkyl methanesulfonates viz. methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate in doxazosin mesylate has been presented by using selective ion monitoring mode. The optimum separation was achieved between methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate on a DB-5 (30 m×0.32 mm×1.0 μm) capillary column under programming temperature. Acetonitrile, water and ammonia (90:9:1 v/v/v) mixture was used as diluent. Various factors involved in the gas chromatography-mass spectrometry method development are also presented. This method was validated as per International Conference on Harmonization guidelines. The limit of quantitation of methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate is 6 ppm with respect to 30 mg/ml of doxazosin mesylate.

GC-ECD/MS를 이용한 농산물 중 Captan, Folpet, Captafol 및 Chlorothalonil의 잔류분석법

A gas chromatographic (GC) method was developed to determine residues of captan, folpet, captafol, and chlorothalonil, known as broad-spectrum protective fungicides for the official purpose. All the fungicide residues were extracted with acetone containing 3% phosphoric acid from representative samples of five agricultural products which comprised rice, soybean, apple, pepper, and cabbage. The extract was diluted with saline, and dichloromethane partition was followed to recover the fungicides from the aqueous phase. Florisil column chromatography was additionally employed for final cleanup of the extracts. The analytes were then determined by gas chromatography using a DB-1 capillary column with electron capture detection. Reproducibility in quantitation was largely enhanced by minimization of adsorption or thermal degradation of analytes during GLC analysis. Mean recoveries generated from each crop sample fortified at two levels in triplicate ranged from 89.0~113.7%. Relative standard deviations (RSD) were all less than 10%, irrespective sample types and fortification levels. As no interference was found in any samples, limit of quantitation (LOQ) was estimated to be 0.008 mg/kg for the analytes except showing higher sensitivity of 0.002 mg/kg for chlorothalonil. GC/Mass spectrometric method using selected-ion monitoring technique was also provided to confirm the suspected residues. The proposed method was reproducible and sensitive enough to determine the residues of captan, folpet, captafol, and chlorothalonil in agricultural commodities for routine analysis.

Fast analysis of multiple pesticide residues in apple juice using dispersive liquid–liquid microextraction and multidimensional gas chromatography–mass spectrometry

A method for the rapid trace analysis of 24 residual pesticides in apple juice by multidimensional gas chromatography–mass spectrometry (MD-GC/MS) using dispersive liquid–liquid microextraction (DLLME) was developed and optimized. Several parameters of the extraction procedure such as type and volume of extraction solvent, type and volume of dispersive solvent and salt addition were evaluated to achieve the highest yield and to attain the lowest detection limits. The DLLME procedure optimized consists in the formation of a cloudy solution promoted by the fast addition to the sample (5 ml) of a mixture of carbon tetrachloride (extraction solvent, 100 μl) and acetone (dispersive solvent, 400 μl). The tiny droplets formed and dispersed among the aqueous sample solution are further joined and sedimented (85 μl) in the bottom of the conical test tube by centrifugation. Once extracted, all the 24 pesticides were directly injected and separated by a dual GC column system, comprising a short wide-bore DB-5 capillary column with low film thickness connected by a Deans switch system to a second chromatographic narrower column, with identical stationary phase. The instrumental setting used, in combination with carefully optimized operational fast GC and MS parameters, markedly decreased the retention times of the targeted analytes. The total chromatographic run was 8 min. Mean recoveries for apple juice spiked at three concentrations ranged from 60% to 105% and the intra-repeatability ranged from 1% to 21%. The limits of detection of the 24 pesticides ranged from 0.06 to 2.20 μg/L. In 2 of a total of 28 analysed samples were found residues of captan, although at levels below the maximum limit legal established.

Automated on-line in-tube solid-phase microextraction coupled with HPLC/MS/MS for the determination of butyrophenone derivatives in human plasma

This paper describes a fully automated on-line method combining in-tube solid-phase microextraction (SPME) in which sample clean-up and enrichment are conducted through an open tubular fused-silica capillary column and high-performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS) detection for the determination of six butyrophenone derivatives (moperone, floropipamide, haloperidol, spiroperidol, bromperidol, and pimozide) in human plasma samples. The six butyrophenones were extracted by repeatedly aspirating and dispensing plasma sample solutions on a DB-17 capillary column (60 cm x 0.32 mm i.d., film thickness 0.25 microm). The analytes retained on the inner surface of the capillary column were then eluted into an acetonitrile-rich mobile phase using a gradient separation technique. Extraction efficiencies ranged from 12.7% to 31.8% for moperone, spiroperidol, and pimozide, and from 1.08% to 4.86% for floropipamide, haloperidol, and bromperidol. The regression equations for all compounds showed excellent linearity, ranging from 0.05 to 50 ng/0.1 mL of plasma, except for moperone and spiroperidol (0.01 to 50 ng/0.1 mL). The limits of detection and quantification in plasma for each drug were 0.03-0.2 and 0.1-0.5 ng/mL, respectively. The intra- and inter-day coefficients of variation for all compounds in plasma were not greater than 13.7%.

Gas Chromatography Residue Analysis of Bifenthrin in Pears Treated with 2% Wettable Powder.

This study was conducted to monitor the level of bifenthrin residues in pear sprayed with 2% bifenthrin wettable powder (WP) at the recommended rate at four different schedules prior to harvest. The target analyte was extracted with acetone, partitioned into dichloromethane, and then purified by florisil chromatographic column. The residue determination was performed on a DB-5 capillary column using GC with electron capture detector (ECD). Linearity of this method was quite good (r2 = 0.9951) in the concentration ranged from 0.2 mg/kg to 10 mg/kg. Recovery test was carried out at two concentration levels, 0.2 mg/kg and 1.0 mg/kg, in three replicates, and their rates were from 82.9% to 107.2%. No quantitative bifenthrin was detected in pear of all kinds of treatments including the treatment sprayed 4 times until 7 days before harvest. This sensitive and selective method can be used to monitor the trace residual amounts of bifenthrin in pear in a quite low concentration level.