Unintended compositional changes in transgenic rice seeds ( Oryza sativa L.) studied by spectral and chromatographic analysis coupled with chemometrics methods.

Unintended compositional changes in transgenic rice seeds were studied by near-infrared reflectance, GC-MS, HPLC, and ICP-AES coupled with chemometrics strategies. Three kinds of transgenic rice with resistance to fungal diseases or insect pests were comparatively studied with the nontransgenic counterparts in terms of key nutrients such as protein, amino acids, fatty acids, vitamins, elements, and antinutrient phytic acid recommended by the Organization for Economic Co-operation and Development (OECD). The compositional profiles were discriminated by chemometrics methods, and the discriminatory compounds were protein, three amino acids, two fatty acids, two vitamins, and several elements. Significance of differences for these compounds was proved by analysis of variance, and the variation extent ranged from 20 to 74% for amino acids, from 19 to 38% for fatty acids, from 25 to 57% for vitamins, from 20 to 50% for elements, and 25% for protein, whereas phytic acid content did not change significantly. The unintended compositional alterations as well as unintended change of physical characteristic in transgenic rice compared with nontransgenic rice might be related to the genetic transformation, the effect of which needs to be elucidated by additional studies.

Study of the alarming volatile characteristics of Tessaratoma papillosa using SPME-GC-MS.

The stinkbug's volatile compositions would alter very much before and after stinkbugs were disturbed or irritated, which caused the alarming effect. An efficient headspace solid-phase microextraction sampling method was established to study the alarming volatile characteristics and potential alarming volatiles of stinkbugs (Tessaratoma papillosa) followed by gas chromatography-mass spectrometry detection. The number of volatiles identified was 16 and 22 before and after stinkbug irritation, respectively. Long-chain alkanes, alkenes, and alcohols consisted of the main volatile compositions of Tessaratoma papillosa. When stinkbugs were disturbed, the typical unsaturated volatiles were released, especially including a series of tridecane derivatives. In comparison with the volatile compounds of lichi leaf and flower (plants the stinkbug eats), it could be seen that most stinkbug alarming volatiles were synthesized by the insects themselves, and that they do not originate from their food. The different statistical alarming volatile characteristics of Tessaratoma papillosa before and after irritation were interpreted by principal component analysis in the original Chromatography Data Processing System. However, temperature and light did not affect the alarming volatile characteristics. The variety of the stinkbug alarming volatile characteristics before and after irritation was specified by common model strategy. Tridecane, [E]-2-hexenal, dodecane, [E]-2-hexen-1-ol acetate, and 2,3-dimethyl-1-pentene contributed most to the various alarming volatile characteristics before and after irritation, which might be the potential alarming volatiles. It is hoped that this work will provide useful information for insect control.

A GC-MS study of the volatile organic composition of straw and oyster mushrooms during maturity and its relation to antioxidant activity.

Mushrooms are very popular in the market for their nutritional and medicinal use. Mushroom volatiles are not only an important factor in the flavor, but also contain many antioxidant compounds. Antioxidant activity is a very important property for disease prevention. The volatile compositional characteristics of straw mushrooms (Volvariella volvacea [Bull. ex Fr.] Sing.) and oyster mushrooms (Pleurotus ostreatus [Jacq. ex Fr.] Kummer) during maturity and the mushroom antioxidant activity related to the non-volatiles and volatiles are studied by a chromatographic method in combination with a spectrophotometric method. The volatile compounds of straw and oyster mushrooms are sampled and identified by a combination sampling method, including headspace solid phase microextraction and steam distillation, followed by gas chromatography-mass spectrometry detection. Among all the volatile compounds identified, 1-octen-3-ol and 3-octanone are the two main compounds with the highest amounts in the volatile compositions of straw and oyster mushrooms. During maturity time of the straw mushrooms, the unsaturated 1-octen-3-ol peak area is reduced, whereas the saturated 3-octanone peak area is increased. However, during normal maturity time of oyster mushrooms, the peak areas of 1-octen-3-ol and 3-octanone remain at the same level. 1-Octen-3-ol has a different antioxidant activity from 3-octanone. Combining the results of antioxidant experiments of water extract and main volatile components by the use of a phosphomolybdenum spectrophotometric method, the conclusion is drawn that oyster mushrooms might possess stronger antioxidant activities than straw mushrooms.

The study of fingerprint characteristics of the emanations from human arm skin using the original sampling system by SPME-GC/MS.

An efficient and noninvasive method consisting of an original sampling device, solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) was developed to analyze volatile organic emanations from the skin of human arms. The emanations were sampled by SPME connected with the active sampling device for 30 min and transferred into GC-MS immediately for the consequent analysis. The sampling projects for 15 candidates were scheduled in both winter and spring with the same optimized conditions. Thirty-five compounds were finally identified according to various degrees of certainty. Different emission behaviors specified with principal component analysis (PCA) and similar fingerprint characteristics were observed clearly by comparisons of chromatograms of different seasons. Top ten emanations contributing to characteristics in different seasons were attempted to be described using comparisons based on common model strategy. The large amounts of experimental data were all handled by the corresponding chemometrics strategies with the homemade chromatographic data processing system. The results suggest that the analysis based on fingerprint characteristics of human skin emanations could provide useful and important clues to reveal biomarkers among the mixture of human skin emanations.

[Determination of organophosphorus pesticides in vegetables by microwave-assisted extraction/gas chromatography-mass spectrometry].

A method of microwave-assisted extraction (MAE) followed by gas chromatography-mass spectrometry (GC-MS) for the determination of organophosphorus pesticides (OPPs) in vegetables has been developed. The OPPs studied were diazinon, parathion and isocarbophos. Several extraction solvents were compared on the MAE efficiency. Dichloromethane gave good recovery, and was chosenfor the procedure. A three-level orthogonal array design was used to optimize the MAE process.Factors affecting the MAE efficiency were considered, including the solvent amount and extraction time.The linear ranges of the method were from 4 ng/g to 400 ng/g for diazinon and parathion, and from 20 ng/g to 400 ng/g for isocarbophos. The detection limits were 0.29 ng/g, 1.70 ng/g and 2.30 ng/g for diazinon, parathion and isocarbophos respectively. Two sets of spiked vegetable samples of 200.0 ng/g and 50.0 ng/g were determined. The recoveries were from 72.2% to 102.0%, and the RSDs were from 1.5% to 11.0% (n = 3). The analytical results agreed quite well with those obtained by conventional extraction with mechanical shaking (EMS). The method is fast and solvent-saving.