SIM Mode Research Articles

Determination of Selected Pesticide Residues in River Water Using SBSE Technique

The analytical procedure based on stir‑bar sorptive extraction technique, for the determination of selected pesticide residues (diazinon, malathion, cyprodinyl, penconazole, fludioxonyl, pyriproxyfen, boscalid, pyraclostrobin) is described. Analysis was performed using the commercial TwisterTM stir bar for sorptive extraction. It consists of a 2.0‑cm‑long glass‑encapsulated magnetic stir bar externally coated with PDMS. The extracts were off‑line analyzed using fast GC‑MS in SIM mode. Optimized conditions were established as follows concerning extraction time, stirring speed, aqueous medium characteristics (ionic strength and polarity) respectively: 120 min (700 rpm), addition of 4 g of sodium chloride, no addition of methanol as organic modifier, and 30 min ultrasonic desorption in acetonitrile. Recoveries ranged from 38 % to 58 % (RSD < 15 %, n = 6). Validated limits of quantification in matrix were between 1.6 ngL−1 and 548.8 ngL−1, depending on the compound.

Rapid analysis of benzalkonium chloride using paper spray mass spectrometry

A paper spray mass spectrometry (PS-MS) method for rapid and reliable analysis of benzalkonium chloride (BAC) in compound eye drops and body surface disinfectant was developed. The sample was dropped onto triangular filter paper, and high voltage (3.5kV) was applied to form an electrospray. This method can provide the composition of benzalkonium chloride in samples without pretreatment, solvent or chromatographic separation, and the analysis time is only 10s. The primary homologues C12-BAC, C14-BAC and C16-BAC of benzalkonium chloride were quantitatively analyzed using PS-MS. Samples were subjected to simple dilution and quantified using the internal standard method. Ion trap mass spectrometry was scanned using SIM mode. The linear ranges of C12-BAC, C14-BAC and C16-BAC were 1–100μgmL−1; the linear regression coefficients were 0.998–0.999; the detection limits (LODs) were 0.1μgmL−1; the limit of quantifications (LOQs) was <1μgmL−1, and the method validation indicated that the method precision and accuracy were good. Compared with HPLC-UV methods, there was no significant difference in the quantitative determination of the actual samples, but the analysis time for PS-MS is shorter (2min). In addition, reagent consumption in PS-MS is small, and no chromatographic separation is needed, suggesting that PS-MS is especially suitable for high-throughput analysis.

Comparative Study of Three Varieties of Cannabis sativa L. Cultivate in Different Region of Morocco

In this study, an experiment of hemp crops was conducted between in four different regions of the country, and concerned three varieties Santhica 27, Epsilon 68 and Futura 75. The tests were conducted in areas with geographical, climatic and soil characteristics different than European cultures, that’s why it was necessary to verify the behavior of these plants by controlling their Δ-9-THC content. Sampling, drying and Δ-9-THC evaluation in these crops were performed according to procedure B of European Regulation, and using a simplified method based on the determination of the ratio α = Δ-9- THC/CBD. The best dry matter yields, plant height and density are obtained with the variety Futura 75 in the four sites, followed by Epsilon 68 and Santhica 27. The average contents of these crops in Δ-9-THC were ranged from 0.013% to 0.027% for the variety Epsilon 68, between 0.023% and 0.035% for the variety Futura 75. Analysis of this latter variety by GC / MS SIM mode and LC/MS/MS allowed the identification of traces of Δ-9-THC. In the other hand, the ratio α has been evaluated to 0.042 and 0.047 respectively for Epsilon 68 and Futura 75 varieties which is similar to those usually obtained for hemp fiber crops and stays much lower than 0.2. The Principal Component Analysis confirms the existence of possible correlations for each variety separately. Overall, the results reveal the existence of correlations between different parameters including the one between the dry matter yield, plant height and density.

Determination of potential off-flavour in yeast extract

Yeast extracts is a kind of food ingredient for enhancing flavor, but some yeast extract samples had yeasty odour (off-flavour). The aim of this study was to detect key aroma compounds leading to the yeasty odour. Volatile compounds of 3 yeast extracts (with yeasty odour), FA and FB, LC were extracted by solid phase micro-extraction (SPME) and solvent assisted flavour evaporation (SAFE) respectively, and analysed by gas chromatography-olfactrometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA) techniques. Thirty aroma-active compounds were detected, among them 4-methylphenol, 3-methylpyridine, 3-methylbutanoic acid, propanoic acid with high FD factors (FD = 125, 125, 625, 125, ≥25), were identified as the key off-flavours responsible for yeasty and their accurate quantification were done by external standard method in SIM mode. Calculation of the OAVs revealed 3-methylbutanoic acid, 3-methylpyridine, 4-methylphenol as the key odourants in the extract. For the verification of analyzed off-flavours, sensory evaluations of aroma model were conducted by eight panelists, and the result showed that aroma recombinate had the yeasty odour profile similar with the original yeast extracts.The methods were successful for the detection of off-flavors in yeast extract and the four off-compounds analyzed were mainly responsible for the yeasty flavour.

Cryofocusing capillary microextraction of volatiles (Cryo-CMV) as a novel headspace extraction device for the analysis of volatile organic compounds and smokeless powders

A novel field sampling device for fast, sensitive, dynamic headspace sampling of volatile organic compounds (VOCs) and smokeless powders from air is described. The capillary microextraction of volatiles (CMV) is an inexpensive, preconcentration technique that results in fast sampling times (as low as 2min) with high efficiency and sensitivity. Analysis of the CMV with GC–MS is achieved with a thermal desorption probe to introduce the CMV directly into the injection port of a GC. A cryofocusing device consisting of a Peltier-cooled module that operates down to −10°C was employed to improve the extraction efficiency of the CMV for sampling both VOCs and smokeless powders.The method performance using the CMV for the analysis of 17 VOC’s, including the BTEX compounds (Benzene, Toluene, Ethylbenzene, and Xylenes) is demonstrated using the criteria established by the Environmental Protection Agency (EPA) for sorbent tube sampling of toxic organic compounds in ambient air (EPA TO-17). Experimental results with known standards yield absolute mass detection limits ranging from 2.0 to 4.6ng for the target compounds, in a 2L air sample. A 35–100% improvement in the analytical performance was achieved by sampling at −10°C, in comparison to 20°C, for most compounds. Using cryofocusing conditions, precision of 8–53 %RSD was achieved for headspace extraction for the majority of the compounds with recoveries of as much as 37% and low breakthrough. Furthermore, the headspace calibration curves show a linearity of 0.951 or better for the target compounds, suggesting the quantitation capabilities of the CMV device.The CMV method performance was further demonstrated for the detection of markers above the headspace of smokeless powder. Experimental results with known standards, yield method detection limits of 2.0ng and 1.3ng for nitroglycerine (NG) and diphenylamine (DPA), respectively, in a 2L air sampling volume followed by simultaneous SIM mode GC–MS analysis. Using cryofocusing conditions for the headspace extraction of Hodgdon smokeless powder, a 29–38% improvement in the analytical performance of NG was achieved with 18 %RSD precision, by sampling at 2.5°C to −10°C, in comparison to room temperature at 20°C.

Super-SILAC mix coupled with SIM/AIMS assays for targeted verification of phosphopeptides discovered in a large-scale phosphoproteome analysis of hepatocellular carcinoma

Plentiful studies have established a close association between aberrant phosphorylation and hepatocellular carcinoma (HCC). Here, we applied a quantitative phosphoproteomics platform combining dimethylation labeling and online 3D strong cation exchange chromatography (SCX)-titanium oxide (TiO2)/RP-LTQ-Orbitrap to compare phosphoproteomes between three pairs of HCC tissues and non-tumor counterparts. This analysis yielded 7868 quantifiable phosphopeptides and numerous up- or down-regulated candidates. Increased phosphorylation of LMNA and NIPA was confirmed using specific antibodies. To expand our verification capability, we evaluated the use of LTQ-Orbitrap run in SIM/Accurate inclusion mass screening (AIMS) mode with a super-SILAC mixture as an internal standard to quantify a subset of phosphopeptide candidates in HCC tissue samples. In sample I used for discovery experiment, we successfully quantified 32 (in SIM mode) and 30 (in AIMS mode) phosphopeptides with median coefficients of variation (CVs) of 7.5% and 8.3%, respectively. When the assay was applied to other three pairs of HCC specimens for verification experiment, 40 target phosphopeptides were quantified reliably (~7.5% CV), and more than half of them were differentially expressed between tumor and adjacent non-tumor tissues. Collectively, these results indicate the feasibility of using super-SILAC mix-SIM/AIMS assays for targeted verification of phosphopeptides discovered by large-scale phosphoproteome analyses of HCC specimens. SignificanceIn this study, we developed a strategy for conducting both discovery and targeted verification of deregulated phosphoproteins in HCC tissue specimens on LTQ-Orbitrap. This strategy allowed us to generate a quantitative HCC tissue phosphoproteome dataset containing significantly deregulated phosphoproteins that represents a valuable resource for the identification of potential HCC biomarkers and/or therapeutic targets. Furthermore, our proof-of-concept experiments demonstrated the feasibility of applying LTQ-Orbitrap, operated in SIM/AIMS mode, to multiplex and targeted verification of phosphopeptides in individual tissue specimens using a super-SILAC mix as an internal phosphopeptide standard. This method could be readily applied to verify dozens of phosphopeptide candidates in a larger HCC sample set.

Determination of aliphatic amines in food by on-fiber derivatization solid-phase microextraction with a novel zeolitic imidazolate framework 8-coated stainless steel fiber

Some harmful aliphatic diamines, e.g., putrescine (Put) and cadaverine (Cad), play important roles in food safety evaluation. In this study, we proposed on-fiber derivatization solid-phase microextraction analysis of non-volatile aliphatic diamines in fish using zeolitic imidazolate framework 8 (ZIF-8) as a solid-phase microextraction (SPME) coating. It was employed to encapsulate isobutyl chloroformate (IBCF, 40°C, 15min) for aqueous extraction of Put and Cad. After that, the derivatized aliphatic amines were thermally desorbed in the GC injection port and analyzed by GC-MS. The porous and hydrophobic ZIF-8 with high surface area can increase the IBCF loading amount and prevent it from decomposing, thus increasing the amine extraction effectiveness and sensitivity. In SIM mode and using the molecular ion for quantification, the limits of detection for Put and Cad were 27.1 and 33.2μgL−1, respectively under the optimal conditions. The fiber-to-fiber reproducibility values (RSDs) for three ZIF-8 coated fibers were less than 11.4% for both Put and Cad. The extraction with the new fiber was reproducible for at least 30 cycles without a noticeable decrease of performance (RSD<10%). The new fiber was successfully applied to the detection of putrescine and cadaverine in several fish samples and showed good recoveries (78.6–104%).

Liquid chromatography-high-resolution mass spectrometry for regulated bioanalysis: bile acid and oligonucleotide quantitation as a reference.

Liquid chromatography-high-resolution mass spectrometry for regulated bioanalysis: bile acid and oligonucleotide quantitation as a reference.

시안화이온의 pentafluorobenzyl bromide (PFBBr)에 의한 유도체화 후 GC/MS 분석에 의한 차량화재 변사체 사인규명에 관한 사례연구

시안화수소는 ABS (acrylonitrile-butadiene-styrene) 등의 플라스틱류 화재시에 발생될 수 있는 유독성 기체이기에 시안화수소가 함유된 연기를 흡입하였을 경우 변사자의 혈액에서도 검출될 수 있다. 따라서 열기로 혈액 등의 생체시료의 손상정도가 강하여 일산화탄소-헤모글로빈 농도의 측정이 어려운 경우 사인규명을 위한 지표로 활용될 수 있으리라 사료된다. 본 연구의 사례는 유서와 함께 화재가 발생한 차량내에서 발견된 변사체의 사인규명과 관련이 있다. 화재사의 경우 일산화탄소-헤모글로빈 농도가 결정적인 정보를 제공하지만 열기로 심하게 손상되어 이에 대한 측정이 어려워 시안화이온을 분석하고자 하였다. 시안화이온을 양이온계면활성제와 함께 pentafluorobenzyl bromide로 유도체화 시킨 다음 기체크로마토그래피/질량분석법으로 scan mode와 SIM mode로 분석하였다. 변사체 심혈과 뇌혈에서 시안화이온이 정상 흡연자 14인의 평균값(0.041 &#xB5;g/mL)보다 높은 0.36 &#xB5;g/mL 및 1.20 &#xB5;g/mL 확인되었다. Hydrogen cyanide (HCN) is an extremely toxic gas frequently produced during the incineration of plastics, such as acrylonitrile-butadiene-styrene (ABS). A victim of a fire who has inhaled smoke could have cyanide in the blood. Therefore, cyanide could be a good marker for a post-mortem examination of a fire as well as carboxyhemoglobine (COHb) test of blood samples. For a particular fire case, a burned body with a suicide note was found inside a burned vehicle. Even though the COHb value is conclusive evidence, measuring the COHb for denatured blood might be difficult due to severe thermal denaturation or the formation of methemoglobin (MetHb). To overcome this difficulty, cyanide could be used as an indicator when investigating the death of a fire victim. In this study, gas chromatography/mass spectrometry (GC/MS) was adopted to measure the levels of cyanide in the blood through derivatization with pentafluorobenzyl bromide (PFBBr) under cation surfactant by scan and SIM mode. The concentration of cyanide in the blood of heart blood and brain of the victim was found to be 0.36 &#xB5;g/mL and 1.20 &#xB5;g/mL respectively, which was higher than the average value (0.041 &#xB5;g/mL) found in the blood of 14 people who smoked.

Analysis of chemical warfare agents in organic liquid samples with magnetic dispersive solid phase extraction and gas chromatography mass spectrometry for verification of the chemical weapons convention

A simple, sensitive and low temperature sample preparation method is developed for detection and identification of Chemical Warfare Agents (CWAs) and scheduled esters in organic liquid using magnetic dispersive solid phase extraction (MDSPE) followed by gas chromatography-mass spectrometry analysis. The method utilizes Iron oxide@Poly(methacrylic acid-co-ethylene glycol dimethacrylate) resin (Fe2O3@Poly(MAA-co-EGDMA)) as sorbent. Variants of these sorbents were prepared by precipitation polymerization of methacrylic acid-co-ethylene glycol dimethacrylate (MAA-co-EGDMA) onto Fe2O3 nanoparticles. Fe2O3@poly(MAA-co-EGDMA) with 20% MAA showed highest recovery of analytes. Extractions were performed with magnetic microspheres by MDSPE. Parameters affecting the extraction efficiency were studied and optimized. Under the optimized conditions, method showed linearity in the range of 0.1–3.0μgmL−1 (r2=0.9966-0.9987). The repeatability and reproducibility (relative standard deviations (RSDs) %) were in the range of 4.5–7.6% and 3.4–6.2% respectively for organophosphorous esters in dodecane. Limits of detection (S/N=3/1) and limit of quantification (S/N=10/1) were found to be in the range of 0.05–0.1μgmL−1 and 0.1–0.12μgmL−1 respectively in SIM mode for selected analytes. The method was successfully validated and applied to the extraction and identification of targeted analytes from three different organic liquids i.e. n-hexane, dodecane and silicon oil. Recoveries ranged from 58.7 to 97.3% and 53.8 to 95.5% at 3μgmL−1 and 1μgmL−1 spiking concentrations. Detection of diethyl methylphosphonate (DEMP) and O-Ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX) in samples provided by the Organization for Prohibition of Chemical Weapons Proficiency Test (OPCW-PT) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals.

Study on biological monitoring indicators of exposure to 1,2-dichloroethane and its determination method in blood

To investigate the feasibility of using the concentration of 1,2-DCE in blood as a biological monitoring indicators and build the determination method of 1,2-DCE in blood. Dose-response relationship of the exposure of 1,2-DCE and the level of 1,2-DCE in rat blood were investigated using the Pearson's correlation analysis. The concentration of 1,2-DCE in blood was determined using Headspace Sampler-Gas Chromatography-Mass Spectrometer (HS-GC-MS). 3.0 ml blood sample diluting with 2.0 ml 1,2-DCE standard serial solution was placed in 15 headspace bottles respectively and heated at 80 ℃ for 20 min.The vapor upon the headspace bottle was separated by capillary column and the concentration of 1,2-DCE was determined by massspectrum in SIM mode to draw a standard work curve. The within-run precision and the between-run precision were calculated by the relative standard deviation (RSD) of the concentration of 1,2-DCE in blood which was determined 6 times in a day and 6 times within 3 days respectively. The recovery rate was calculated by P=(C2 -C0)/C1 × 100%. When the treatment groups were exposed at dosage of 1,472, 2,550, 3,093, 3,976, and 4 418 mg/m(3), the average concentration of 1,2-DCE in rat blood was 24.1,231.6,344.3,395.1,538.5 μg/L. There was a positive correlation between the concentration of 1,2-DCE in rat blood and the exposed level of 1,2-DCE.The equation of dose-response relationship was y=0.162x -195.8,r=0.982 2,P=0.003 and the precision of exposure experiments was 7.04% -13.15%. 1,2-DCE contents within 0.259 -2 587 μg/L showed a good linear relationship and the regression equation was y=47 901x -357 446, r= 0.999 8. When the blood containing 0.259 μg/L 1,2-DCE was determined for six times, the average peak/peak signal-to-noise ratio was 56.55. The limit of detection (LOD) was 0.014 μg/L and the limit of quantification (LOQ) was 0.046 μg/L. The within-run precision was 1.23% -2.76% and the between-run precision was 2.21% -4.64%. The average recovery rate was 93.3% - 98.6%. The concentration of 1,2-DCE in blood could be used as a biological monitoring indicator. The method of the concentration of 1,2-DCE in blood determining by HS-GC-MS was characterized by high sensitivity, wide linear range, small interference, high precision and easy operation.

Structure prediction of methyoxy-polybrominated diphenyl ethers (MeO-PBDEs) through GC–MS analysis of their corresponding PBDEs

It is hard to quantify the trace pollutants in the environment without the corresponding reference standards. Structure identifications of unknown organic pollutants are thus of great importance in environmental analysis. As for polybrominated diphenyl ethers (PBDE) with one substituent of methoxyl group, there are 837 congeners, but only 32 standards are commercially available. In this work, an effective method based on gas chromatography coupled with mass spectrometry (GC–MS) was proposed to predict the potential structures of methoxylated polybrominated diphenyl ethers (MeO-PBDEs). The mass fragmentation pattern using SIM mode not only provided the useful information on the substitution position of methoxyl group, the number of Br atoms, but also guaranteed the high sensitivity for trace analysis. Br distribution patterns of the unknown MeO-PBDEs were revealed by a linear regression model with dummy variables which described the retention time relationship between MeO-PBDEs and the corresponding PBDEs on different types of GC columns. This method was successfully used to identify three new MeO-PBDEs metabolites of BDE-28 as 4-MeO-BDE-22, 4′-MeO-BDE-25 and 4-MeO-BDE-31 in the pumpkins. Therefore, the newly developed structure prediction model based on GC–MS behavior is helpful in the evaluation of unknown PBDE metabolites in the environment.

Environmental pollution of polybrominated diphenyl ethers from industrial plants in China: a preliminary investigation

Although numerous studies have shown the presence of polybrominated diphenyl ethers (PBDEs) in various environmental media, attention to their distribution in the environmental media surrounding industrial facilities is limited. In this study, eight PBDEs congeners (BDE-28, -47, -99, -100, -153, -154, -183, -209) were investigated in surface soils and water samples collected from commercial PBDE manufacturers, flame-retardant plastic modification plants and waste electrical and electronic equipment recycling facilities in China. Analysis of target compounds was performed using the model NCI GC-MS in SIM mode. The concentrations of ∑8PBDEs varied from 193.1 to 22,004.3 ng/L in water samples and from 1209.3 to 226,906 ng/g dry wt in surface soils, respectively. More severe PBDE contamination, when compared with previously reported data, was found in industrial areas in this study. This indicates that these industrial areas are highly polluted with PBDEs. BDE-209 was the predominant congener, accounting for more than 94% in this study, except for a 68.75% portion at one site. Our results show that PBDE manufacturing and flame-retardant plastic modification plants, easily overlooked by the public, are two primary PBDE pollution sources although they affect surrounding areas. Further research is needed, aimed at managing industrial PBDE emissions and eliminating environmental PBDE pollution, to investigate the material flows and environmental fates of PBDEs in all stages of the life cycle.

Application of dynamic headspace and gas chromatography coupled to mass spectrometry (DHS-GC-MS) for the determination of oxygenated volatile organic compounds in refinery effluents

The paper presents a new procedure for the determination of oxygenated volatile organic compounds in postoxidative effluents from the production of petroleum asphalt using dynamic headspace coupled to gas chromatography-mass spectrometry in SIM mode.

Capillary isotachophoresis with ESI-MS detection: Methodology for highly sensitive analysis of ibuprofen and diclofenac in waters

The possibilities of reaching higher sensitivity in capillary electrophoretic analyses of complex samples with ESI-MS detection were investigated on the example of analysis of diclofenac and ibuprofen in waters. The applied separation approach is based on application of isotachophoresis that ensures permanent stacking of analytes until they reach the detector. Investigation of the possibilities of MS detector optimization have shown that optimization of fragmentor voltage and working in the SIM mode with collection of data for multiple fragments both increases the method specificity and approx. doubles its sensitivity. Combination with an offline SPE preconcentration step resulted in very high sensitivity of the described methodology with a reached LOD below 2 × 10−12 M, corresponding to analyte levels of 0.6 ng L−1 of diclofenac and 0.4 ng L−1 of ibuprofen. The results demonstrate that CE-MS, particularly when performed in the ITP mode, has the potential to reach sensitivities comparable to HPLC-MS.

A pilot survey of 2- and 3-monochloropropanediol and glycidol fatty acid esters in baby formula on the Canadian market 2012–2013

Occurrence of 2- and 3-monochloropropanediol esters and glycidol esters (MCPDEs and GEs) in 34 baby formulae on the Canadian market was examined. Products were purchased in 2012 and again in 2013. GEs – esters of palmitic, stearic, oleic, linoleic and linolenic acids – were determined via direct analytical approach by stable isotope dilution analysis (SIDA) LC–MS/MS using glycidol-d5 labelled standards. For the analysis of MCPDEs (expressed as free MCPD equivalents), one 2-MCPD-d5 and one 3-MCPD-d5 labelled diesters were employed using indirect analytical approach. MCPDs were determined by SIDA GC–MS in SIM mode. 2- and 3-MCPDEs were detected (at levels >2ng/g and >6ng/g, expressed as free monochloropropanediol (MCPD) equivalents respectively) in 15 samples in 2012 and in 14 samples in 2013. The levels of 2-MCPDs reached maxima of 47ng/g in 2012 samples and 32ng/g in 2013 samples. The levels of 3-MCPDs reached maxima of 89ng/g in 2012 samples and 80ng/g in 2013 samples. The levels of sum of MCPDs detected in 2013 samples were lower as compared to 2012, with respective means of 26 and 43 and maxima of 108 and 135ng/g. The ratio of 3- to 2-MCPD in samples varied from 1.6 to 3.6 with the median of 2.56. GEs were detected (at levels >2ng/g for each individual GE expressed as glycidol equivalent) in 12 samples in 2012 and in 8 samples in 2013. The levels of GEs expressed as glycidol equivalents reached maxima of 70ng/g in the 2012 samples and 40ng/g in the samples collected in 2013 with respective means of 21ng/g and 20ng/g.

Blowfly Larval Tissues as a Secondary Detector for Determining Paraquat‐Related Death in Rabbit Carcass

Paraquat poisoning is commonly associated with suicide or homicide in Malaysia. In a case involving advanced body decomposition, pathological analysis regarding the cause of death may become difficult or almost impossible. Insects serve as common alternative matrix for poison detection in forensic analysis. Paraquat detection via secondary bioaccumulation in fly larvae tissue has never been reported. In this study, tissues from blowfly larvae collected from a rabbit carcass with paraquat poisoning were analyzed for secondary bioaccumulation. Larvae samples were collected and analyzed using liquid-liquid extraction. The detection was performed via reduction of quaternary ammonium presence in paraquat and analyzed using gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring mode (SIM mode). GC-MS showed the elution of reduced paraquat was at retention time 12.8min. Blowfly larvae tissue has proven useful as a secondary detector in paraquat-related deaths.

In situ determination of the syringyl/guaiacyl ratio of residual lignin in pre-bleached eucalypt kraft pulps by analytical pyrolysis

Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550°C, using a 60m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans-4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans-isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.

Gas Chromatography-Mass Spectrometric Method for Simultaneous Separation and Determination of Several Pops with Health Hazards Effects

The hazards effect of persistent organic pollutants, POPs, on the human health has lead us to modify the ASTM method D-5175 to enhance both sensitivity and selectivity of their simultaneous separation. As their separation is difficult- due to the similarity in their chemical and physical properties- that lead to co-elution in extraction, we proposed a validated method for their simultaneous determination using liquid/liquid microextraction followed by GC/MS in the SIM mode. The method is advantageous since the time needed for the chromatographic analysis of all analytes is less than 17 min. Method Detection Limits (MDLs) and Limit of Detection (LODs) reached sub- ppb levels and in many cases are lower than those achieved in the standard test method ASTM D-5175 for many analytes. Besides, three pesticides namely: Hexachlorocyclopentadiene, p,p’-DDE and trifluralin have been added to the method with good accuracy and precision. Application to several environmental samples has been successfully assessed and supported by proficiency testing samples provided from Absolute Standards®, Inc.

Otimization of extraction solid phase method for determination of atrazine by gas chromatography

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-striazina), a herbicine from the family of s-triazine, widely used all over the world, has been detected in ground and surface waters in worrying levels of concentration. This compound has a low potential for bioaccumulation, moderate adsorption and mobility in soil. One way 1 Dra.; Fisica; Professora do Colegio Estadual do Parana; Endereco: Avenida Joao Gualberto, 250, Alto da Gloria, CEP: 80030-000, Curitiba, Parana, Brasil; E-mail: crisneiverth@yahoo.com.br Ambiencia Guarapuava (PR) v.11 n.2 p. 475 482 Jan./Abr. 2015 ISSN 1808 0251 Recebido para publicacao em 09/05/2012 e aceito em 16/10/2014 DOI:10.5935/ambiencia.2015.02.14nt Ambiencia Revista do Setor de Ciencias Agrarias e Ambientais V.11 N.2 Jan./Abr. 2015 476 is to determine atrazine is by Gas Chromatography coupled to Mass Spectrometry (CG-MS), using for the sample preparation the extraction in solid phase (SPE), which eliminates interferences and pre-concentrates the sample into a single step. This research aimed to develop a methodology for analysis of atrazine in water using Solid Phase Extraction in Gas Chromatography coupled with the Mass Spectrometry. The recovery was studied at two concentration levels (0.2 and 2.0 mg L-1), comparing the SIM and MS / MS. For quantification, the SIM method showed a better recovery (98% and 105%) and coefficient of variation (1.6%) at a concentration of 2.0 mg L-1. The detection limit of the SIM mode was 0.20 ng L-1 and the method was tested in surface water and leachate water of undisturbed soil columns of three headwaters. Only two samples of leachate water had concentrations of atrazine above those permitted by law (2.0 mg L-1).