Propolis is a resinous natural product collected by honeybees (Apis mellifera and others) from tree exudates that has been widely used in folk medicine. The present study was carried out to investigate the fatty acid composition, chemical constituents, antioxidant, and xanthine oxidase (XO) inhibitory activity of Jordanian propolis, collected from Al-Ghour, Jordan. The hexane extract of Jordanian propolis contained different fatty acids, which are reported for the first time by using GC-FID. The HPLC was carried out to identify important chemical constituents such as fatty acids, polyphenols and α-tocopherol. The antioxidant and xanthine oxidase inhibitory activities were also monitored. The major fatty acid identified were palmitic acid (44.6%), oleic acid (18:1∆9cis, 24.6%), arachidic acid (7.4%), stearic acid (5.4%), linoleic acid (18:2∆9–12cis, 3.1%), caprylic acid (2.9%), lignoceric acid (2.6%), cis-11,14-eicosaldienoic acid (20:2∆11–14cis, 2.4%), palmitoleic acid (1.5%), cis-11-eicosenoic acid (1.2%), α–linolenic acid (18:3∆9–12–15cis, 1.1%), cis-13,16-docosadienoic acid (22:2∆13–16cis, 1.0%), along with other fatty acids. The major chemical constituents identified using gradient HPLC-PDA analysis were pinocembrin (2.82%), chrysin (1.83%), luteolin-7-O-glucoside (1.23%), caffeic acid (1.12%), caffeic acid phenethyl ester (CAPE, 0.79%), apigenin (0.54%), galangin (0.46%), and luteolin (0.30%); while the minor constituents were hesperidin, quercetin, rutin, and vanillic acid. The percentage of α-tocopherol was 2.01 µg/g of the lipid fraction of propolis. Antioxidant properties of the extracts were determined via DPPH radical scavenging. The DPPH radical scavenging activities (IC50) of different extracts ranged from 6.13 to 60.5 µg/mL compared to ascorbic acid (1.21 µg/mL). The xanthine oxidase inhibition (IC50) ranged from 75.11 to 250.74 µg/mL compared to allopurinol (0.38 µg/mL). The results indicate that the various flavonoids, phenolic compounds, α-tocopherol, and other constituents which are present in propolis are responsible for the antioxidant and xanthine oxidation inhibition activity. To evaluate the safety studies of propolis, the pesticide residues were also monitored by LC-MS-MS 4500 Q-Trap. Trace amounts of pesticide residue (ng/mL) were detected in the samples, which are far below the permissible limit as per international guidelines. 相似文献
Stir bar sorptive extraction (SBSE) is a microextraction technique, introduced to overcome the problem of limited extraction capacity and fragile fiber coatings inherent in the solid phase microextraction technique. The major limitations of the SBSE technique are that only polydimethylsiloxane has been commercially available, this reduces its use to non-polar analytes, and its tedious reconstitution step which can lead to loss of analytes and introduction of impurities. The current trend has been aimed at the use of other materials, some of which are commercially available, such as restricted access materials, carbon adsorbents, molecularly imprinted polymers, ionic liquids, microporous monoliths, sol–gel prepared coatings and dual phase material. This has greatly helped in widening the applications of SBSE for pesticide analysis in fruits and vegetables and other matrices. The introduction of a thermal desorption unit which eliminates the reconstitution step of the stir bar in organic solvents before instrumental analysis has helped to automate the extraction method online with gas chromatography. This paper reviews the use of SBSE in pesticide residues analysis in fruits and vegetables, with a view on sample preparation steps, method optimization and validation of analytical figures of merit. 相似文献
A facile,rapid and sensitive spectrophotometric method was developed for the determination of carbaryl in itsformulations,water and grain(rice and wheat)samples with newly synthesised reagent.The proposed method wasbased on the alkaline hydrolysis of carbaryl pesticide and thus resulted 1-naphthol was coupled with diazotised4,4'-methylene-bis-m-nitroaniline in basic medium(pH 9)to give red colored product having λ_(max)480 nm for dia-zonium method(DM)or 1-naphthol reacts with 4,4'-methylene-bis-m-nitroaniline in the presence of oxidising agentpotassium dichromate(K_2Cr_2O_7)to give red colored product having λ_(max)510 nm for oxidation method(OM).Theformation of colored derivatives with the coupling agent is instantaneous and stable for 48 h(DM)and 32 h(OM)respectively.Beer's law was obeyed in the concentration range of 0.2—10.0 μg·mL~(-1)for DM and 0.2—0,150μg·mL~(-1)for OM.The proposed methods are sensitive,easy to operate and permitted for the determination of car-baryl with detection limits of 0.028 μg·mL~(-1)for DM and 0.024 μg·mL~(-1)for OM respectively.The experimentalresults indicate that the procedure can eliminate the fundamental interferences caused by other pesticides andnon-target ions,which made the methods more sensitive and selective.The method was applicable to the determina-tion of carbaryl residue in water and food grain samples up to μg level. 相似文献
Abstract A multi-residue method was developed to determine pesticides in foods using analyte protectants to compensate for matrix effects. Promising analyte protectants and combinations of these analyte protectants were evaluated for masking active sites in gas chromatography systems. The optimal combination of analyte protectants was determined to be the mixture of polyethylene glycol and olive oil. Calibration curves for analyte protectants in both neat solvents and matrix-matched standards were compared and similar response enhancement was observed. This result suggests a convenient calibration method using a combination of analyte protectants in neat solvent instead of the conventional matrix-matched standards calibration method. 相似文献
Three types of solvent extraction methods (by soxhlet, sonicator and microwave) for pesticide recoveries in solid matrices were compared and evaluated using the standard addition method. Variables (solvent and extraction time) for the optimization of microwave assisted extraction (MAE) were also studied. Three organochlorine pesticides (BHC, DDE, and Dildrin) were chosen for this particular study because of their great presence in the soil where the samples were collected and their positive association with the risk of breast cancer. Comparison of the results obtained indicates that the efficiency of extraction varies, depending on the matrices and the pesticides analyzed. The study focused on the variation in the extraction quantities of different methods in different matrices. The extraction conditions were optimized for MAE with a single matrix (bark) and applied to the rest in order to study the variability in results. Gas chromatography with an electron capture detector (GC–ECD) was used for analysis of the extracts. The results show that even though the use of MAE improved extraction in some of the matrices studied, the extraction method must be optimized whenever a new matrix is evaluated. A statistical comparison indicated that pesticide recoveries and method reproducibility of microwave extraction compared less favorably with the conventional soxhlet method in some of the matrices, whereas the sonicator method was not found to be as efficient as the others. 相似文献
GC-MS investigations were carried out to elucidate the aging behavior of unsaturated fatty acids in fingerprint residues and to identify their degradation products in aged samples. For this purpose, a new sample preparation technique for fingerprint residues was developed that allows producing N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatives of the analyzed unsaturated fatty acids and their degradation products. MSTFA derivatization catalyzed by iodotrimethylsilane enables the reliable identification of aldehydes and oxoacids as characteristic MSTFA derivatives in GCMS. The obtained results elucidate the degradation pathway of unsaturated fatty acids. Our study of aged fingerprint residues reveals that decanal is the main degradation product of the observed unsaturated fatty acids. Furthermore, oxoacids with different chain lengths are detected as specific degradation products of the unsaturated fatty acids. The detection of the degradation products and their chain length is a simple and effective method to determine the double bond position in unsaturated compounds. We can show that the hexadecenoic and octadecenoic acids found in fingerprint residues are not the pervasive fatty acids Δ9-hexadecenoic (palmitoleic acid) and Δ9-octadecenoic (oleic acid) acid but Δ6-hexadecenoic acid (sapienic acid) and Δ8-octadecenoic acid. The present study focuses on the structure identification of human sebum-specific unsaturated fatty acids in fingerprint residues based on the identification of their degradation products. These results are discussed for further investigations and method developments for age determination of fingerprints, which is still a tremendous challenge because of several factors affecting the aging behavior of individual compounds in fingerprints.
