Development and evaluation of gas and liquid chromatographic methods for the analysis of fatty amines

In contrast to the plethora of publications on the separation of fatty acids, analogous studies involving fatty amines are scarce. A recently introduced ionic‐liquid‐based capillary column for GC was used to separate trifluoroacetylated fatty amines focusing on the analysis of a commercial sample. Using the ionic liquid column (isothermal mode at 200°C) it was possible to separate linear primary fatty amines from C₁₂ to C₂₂ chain length in less 25 min with MS identification. The log of the amine retention factors are linearly related to the alkyl chain length with a methylene selectivity of 0.117 kcal/mol for the saturated amines and 0.128 kcal/mol for the mono‐unsaturated amines. The sp² selectivity for unsaturated fatty amines also could be calculated as 0.107 kcal/mol for the ionic liquid column. The commercial sample was quantified by GC with flame ionization detection (FID). An LC method also was developed with a reversed phase gradient separation using acetonitrile/formate buffer mobile phases and ESI‐MS detection. Native amines could be detected and identified by their single ion monitoring chromatograms even when partial coelution was observed. The analysis of the commercial sample returned results coherent with those obtained by GC–FID and with the manufacturer's data.     

Multiresidue method for the fast determination of pesticides in nutraceutical products (Camellia sinensis) by GC coupled to triple quadrupole MS

A method based on QuEChERS (quick, easy, cheap, effective, rugged, and safe) has been developed and validated for the determination and quantification of more than 140 pesticides in nutraceutical products obtained from green tea (Camellia sinensis). Extraction was performed with acidified acetonitrile (acetic acid 1%, v/v) and a clean‐up step using primary secondary amine (50 mg), graphitized black carbon (100 mg) and magnesium sulfate (200 mg) was needed. Pesticide determination was achieved utilizing GC coupled to triple quadrupole MS/MS using the selective‐reaction monitoring mode. The total run time was 23 min. Pesticides were quantified using matrix‐matched calibration. Recoveries ranged from 70 to 120% and relative SD was lower than 25% at 10, 50, and 100 μg/kg. LOQs were lower than 10 μg/kg. 148 pesticides were validated. The validated method was applied to commercial nutraceutical products, detecting 4,4‐dichlorobenzophenone (28 μg/kg), o,p′‐dicofol (38 μg/kg) and p,p‐dicofol (44 μg/kg) in a few samples.     

Enantiomeric distribution of major chiral volatile organic compounds in juniper‐flavored distillates

The enantiomeric ratios of chiral volatile organic compounds in juniper‐flavored spirits produced by various processing technologies in different EU countries were determined by multidimensional GC using solid‐phase microextraction and liquid–liquid extraction as a sample pretreatment procedure. In total, more than 260 compounds were detected in studied spirits from which linalool, α‐terpineol, 4‐terpineol, linalool oxides, α‐pinene, and verbenone were selected for enantiomeric separation. The significant differences in enantiomeric ratio of linalool and cis‐linalool oxide allowed us to distinguish between samples produced in Slovakia and the United Kingdom from those produced in Germany, Czech Republic, and Belgium. The pure enantiomer of trans‐linalool oxide was found only in samples from Germany. It was shown that the enantiomeric ratio is independent of the sample treatment procedure, and only small differences up to 1% were observed.     

Ruellia prostrata Poir. activity evaluated by phytoconstituents,antioxidant, anti-inflammatory,antibacterial activity,and in silico molecular functions

Ruellia prostrata Poir. has been used historically as an anti-cancer, wound healing agent and to treat gonorrhea. We aimed to determine the phytochemicals present in ethyl acetate extract of R. prostrata Poir. (EAERP). We sought to determine the antioxidant, anti-inflammatory, and antibacterial activities in vitro, and toxicity properties in vivo. We also analyzed the Prediction of Activity Spectra for Substances (PASS), physicochemical, ADMET, and drug-likeness properties of phytochemicals in EAERP. To determine phytoconstituents, preliminary phytochemical screening and GC–MS were performed, while FT-IR was used to identify functional groups. The antioxidant activity was evaluated using a DPPH scavenging assay, whereas BSA denaturation and RBC hemolysis inhibition were used to assess anti-inflammatory activity. An agar-well-diffusion assay was performed to estimate the antibacterial activity. Brine shrimp lethality bioassay and oral delivery of EAERP of single-dose were performed to determine cytotoxicity and acute toxicity, respectively. The phytochemical screening revealed the presence of phenols, triterpenoids, saponins, steroids, amino acids, and fat and fixed oils. FT-IR analysis of EAERP showed the presence of many functional groups: alcohols/phenols, carboxylic acids, aldehydes, alkanes, esters, amines, amides, aromatic hydrocarbons, sulfoxides, and alkyl halides. GC–MS revealed the presence of 39 phytoconstituents including steroids, consistent with compounds and functional groups found in preliminary screening and FT-IR. EAERP showed dose-dependent antioxidant activity with an IC₅₀ value of 21.402 µg/mL and anti-inflammatory activity with an IC₅₀ value of 20.564 µg/mL in RBC hemolysis inhibition and 21.115 µg/mL in BSA denaturation assays. EAERP also exhibited dose-related antibacterial activity. EAERP exerted cytotoxicity with an LC₅₀ value of 17.619 μg/mL and acute toxicity with an LD₅₀ value of 4095.328 mg/kg without any adverse effects. The PASS server also predicted that the phytoconstituents of EAERP have antioxidant, anti-inflammatory, and antibacterial activities with probable activity (Pa) ranging from 0.310 to 0.717. Analysis of physicochemical, ADMET, and drug-likeness properties revealed the drug-able efficacy and safety of most compounds. The findings of this study indicated that R. prostrata Poir. contains phytoconstituents with potent antioxidant, anti-inflammatory, and antibacterial activities. Taken together, our measurements suggest that R. prostrata Poir. is a prime candidate for further exploration as a potential therapeutic agent.     

Development of GC–MS/MS method for environmental monitoring of 49 pesticide residues in food commodities in Al-Rass,Al-Qassim region,Saudi Arabia

The harmful effects of pesticide residues are a threat to our health. Therefore, the current study aimed to validate a simple method for the determination of pesticide residues in commonly consumed fruits and vegetables from Al-Rass, Al-Qassim region, Saudi Arabia. A total of 1430 samples were collected from a local market and then analyzed for monitoring of 49 pesticide residues. A quick, easy, cheap, effective, rugged, and safe (QuEChERS) multi-residue extraction method followed by gas chromatography equipped with triple-quadrupole mass spectrometry (GC–MS/MS) was successfully implemented. This 17-min-run analytical method detects and quantifies pesticide residues with acceptable validation performance parameters in terms of sensitivity, selectivity, linearity, the limit of quantification, accuracy, and precision. The linear range of the calibration curves ranged from 10 to 300 µg/L, all the pesticide LODs ranged from 0.0005 to 0.0024 mg/kg, and the pesticide LOQs ranged from 0.0011 to 0.0047 mg/kg. The recovery values at the three fortification levels ranged from 78 % to 107 %, and the precision values (expressed as RSD%) were less than 20 % for all of the investigated analytes. The results showed that 138 (9.65 %) of the analyzed samples were contaminated with pesticide residues, 40 (2.80 %) of the analyzed samples exceeded the maximum residue limit (MRL) of the European Commission regulations (EC) for pesticides residues, 98 (6.85 %) of the analyzed samples were contaminated with residues below the MRL, and 1292 (90.35 %) of the analyzed samples were pesticide residue-free. Coriander contained the highest percentage (46.88 %) of pesticide residues, particularly tetradifon that representing 18.75 % noncompliance with the MRL, followed by parsley, with 20.59 % pesticide residues (10.29 % non-compliance). Multiple pesticide residues were observed most frequently in tomatoes and dates which were contaminated with buprofezin and ethion respectively.     

Preparation and characterization of fragrance by extracting the essential oils from different raw materials

The extraction is a simple process and it is widely used to extract the fragrances in fragrance industries from essential oils. There are number of compounds (i.e. flowers, oils, leaves etc.) from which we can prepare the fragrance by extracting the essential oils from them. In this work, we have prepared the fragrance from the essential oils by the liquid-liquid extraction process, where the essential oil presented as the concentrated hydrophobic liquid containing volatile aroma compounds. We used the combination of Gas chromatography and Mass spectrometry (GC/MS) characterization techniques to make our product more useful, convenient and compitative with the other fragrance available in the market. This study would be helpful to understand the preparation of the fragrance from the concentrated hydrophobic liquid type essential oils which contains volatile aroma compounds by using a significant liquid-liquid extraction process.     

Determination of phthalate esters in liquor samples by vortex‐assisted surfactant‐enhanced‐emulsification liquid–liquid microextraction followed by GC–MS

A novel method using vortex‐assisted surfactant‐enhanced‐emulsification liquid–liquid microextraction has been developed for the extraction of phthalate esters (PAEs) in Chinese liquor samples prior to analysis by GC–MS. In the proposed method, a high‐density extraction solvent (carbon tetrachloride) was dispersed into samples with the aid of a surfactant (Triton X‐100) and vortex agitation, resulting in a short extraction equilibrium (30 s). After centrifugation, a single microdrop of solvent was easily collected for GC–MS analysis. Key factors that affected the extraction efficiency were optimized. Under the optimum conditions, linearity was found in the range from 0.05 to 50 μg/L. Coefficients of determination varied from 0.9938 to 0.9971. LODs, based on an S/N of 3, ranged from 4.9 to 13 ng/L. Enrichment factors varied from 140 to 184. Reproducibility and recoveries were assessed by testing a series of three liquor samples that were spiked with different concentration levels. Finally, the proposed method was successfully applied to the determination of PAEs in 16 Chinese liquor samples. In this work, high‐density‐solvent vortex‐assisted surfactant‐enhanced‐emulsification liquid–liquid microextraction was applied for the first time for the extraction of PAEs in Chinese liquor samples and was proved to be simple, rapid, and sensitive.     

毛细管气相色谱法测定工作场所空气中3种多环芳烃

采用毛细管气相色谱法测定工作场所空气中3种多环芳烃(萘、萘烷和四氢化萘)的含量。样品采用活性炭管采集,二硫化碳解吸20min,用DB-FFAP毛细管气相色谱柱分离,火焰离子检测器检测。3种多环芳烃在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.05~0.5 mg·L-1之间。以空白样品为基体进行加标回收试验,所得回收率在89.3%~97.5%之间,测定值的相对标准偏差(n=6)在2.2%~5.4%之间。     

毛细管柱气相色谱法测定食品中甜蜜素

应用毛细管柱气相色谱法测定了食品中甜蜜素。选择弱极性的DB-5型毛细管色谱柱(0.53mm×30m,1.0μm)作为分离柱,采用氢火焰离子化检测器。对固体样品的处理方法改用粉碎机打碎,并按样品的类别分别用水或经石油醚提取去脂后,再用水超声提取,离心分离并过滤后取其滤液供色谱分析。甜蜜素的质量浓度在0.01~1.0g·L-1范围内与峰面积呈线性相关,检出限(3S/N)为1ng。在3个浓度水平进行加标回收试验,回收率在90.9%~99.5%之间,测定值的相对标准偏差(n=5)在2.9%~6.8%之间。按此法测定了30个食品样品中甜蜜素的含量,所得测定值与欧盟标准方法(EN 12857)测定值相符。     

固相萃取-气相色谱法测定饮用水中12种农药

提出了固相萃取-气相色谱法测定饮用水中12种农药残留量的方法。取水样250mL过固相萃取柱,用乙酸乙酯、正己烷各5mL洗脱,经无水硫酸钠脱水,采用DB-5MS毛细管色谱柱分离,电子捕获检测器检测。溴氢菊酯的线性范围为0.05~0.5mg·L-1,其他农药的线性范围均在0.01~0.1mg·L-1。溴氰菊酯的检出限为24.2ng·L-1,其他农药的检出限均低于10ng·L-1。12种农药的加标回收率在70.0%~110%之间,相对标准偏差(n=6)均小于10%。