A Practical LC-MS/MS Method for the Detection of NDMA at Nanogram per Liter Concentrations in Multiple Water Matrices

N-nitrosodimethylamine (NDMA) is one of the most important disinfection by-products (DBPs) due to its carcinogenicity even at low concentrations which correspond to the levels occurring in drinking water and wastewater effluents. Therefore, NDMA is a candidate DBP that is expected to be regulated in the near future. However, the measurement of NDMA in the low nanogram per liter range is challenging because of the limitations of analytical techniques including both the sample preparation and the LC-MS/MS. Moreover, the accuracy of most of the current methods is only tested for drinking water and no information is present for other matrices. In this study, a combination of solid-phase extraction (SPE) and LC-MS/MS method that does not require high-resolution MS or advanced techniques for sample pretreatment is developed. Moreover, important factors that affect the optimization of the SPE method are provided to enable readers to optimize their own SPE procedures if necessary. The proposed method was validated for surface water, groundwater, and wastewater samples and the method quantification limit was 2?ng/L. In addition, the proposed method was used to determine the concentration of NDMA precursors measured as NDMA formation potential (NDMAFP) throughout a drinking water treatment plant at two different sampling periods. NDMAFP decreased by approximately 40?% in both samples. The concentrations ranged between 4 and 11.5?ng/L and the presence of these low concentrations underlines the need for an easy to use, yet sensitive method for the determination of NDMA in environmental matrices.     

Effect of accelerated aging on some physical and mechanical properties of bamboo

The objective of this study was to investigate the effect of accelerated aging on compression strength, modulus of rupture, modulus of elasticity, color change, volumetric swelling, and volumetric shrinkage of bamboo specimens with and without node sections. In the study, these properties were compared with those of Scots pine and beech wood specimens. Depending on bamboo sections, the aging procedure reduced modulus of rupture, modulus of elasticity, and compression strength. Bamboo specimens showed relatively high strength properties compared to wood specimens due to having high density. Strength properties increased from bottom to top of bamboo culms. The presence of nodes in the specimens reduced compression strength and modulus of rupture but affected modulus of elasticity slightly. Remarkable color changes in specimens were observed after aging. Volumetric swelling and shrinkage of bamboo specimens exposed to aging decreased probably due to heat effect of aging procedure.     

Simultaneous Determination of Phorate and Oxyfluorfen in Well Water Samples with High Accuracy by GC-MS After Binary Dispersive Liquid-Liquid Microextraction

The potential risk of pesticides to cause harm to humans and other organisms even at trace levels calls for sensitive and accurate analytical techniques for their simultaneous qualitative and quantitative determinations. In this study, a sensitive binary dispersive liquid-liquid microextraction (B-DLLME) strategy was developed for the simultaneous determination of phorate and oxyfluorfen by gas chromatography mass spectrometry after extraction/preconcentration from aqueous solution. An experimental design was used to optimize parameters of the B-DLLME method to obtain maximum outcome. Under the optimum conditions of B-DLLME, the limit of detection (LOD) for phorate and oxyfluorfen were found to be 0.41 μg L^?1 and 0.54 μg L^?1, respectively. The detection limits correlate to about 37 and 73 folds enhancement in detection powers when compared to direct GC-MS determination of phorate and oxyfluorfen, respectively. In order to find out the applicability of developed method to real samples, recovery tests were performed for 20 μg L^?1 of phorate and oxyfluorfen spiked in well water samples. Percent recovery values were found to be 94.5% for phorate and 101.9% for oxyfluorfen.     

The Biological Control of Fusarium oxysporum,the Causal Agent of Potato Rot

This study was carried out in vivo and in vitro to search the biological control possibilities of soil borne dry rot causal agent Fusarium oxysporum causing yield losses in potato. In this study, 2 Pantoea agglomerans (BRTB and RK-92), 2 Bacillus pumilus (RK-103 and TV-67C), 7 Bacillus subtilis (BAB-140, TV-12H, TV-6F, EK?7, TV-17C, CP?1 and TV-125A), 3 Bacillus megaterium (TV-103B, TV-87A and TV-91C), 1 Ochrobactrum anthropi (A-16B), 1 Agrobacterium radiobacter (A-16) and 1 Bacillus thuringiensis subsp. kurstaki (BAB-410) bacterial and 2 Trichoderma harzianum (ET 4 and ET 14) fungal isolates tested efficacy in previous studies were used. In pot trial, the experiment was established with the most effective five bacterial strains (BRTB 66.22%; RK-103, 50.90%; BAB-140 50.00%; TV-103B 49.10%; TV-12H 48.65% and TV-6F 48.20%) and two fungal isolates (ET 4; 69.44%, ET 14; 66.66%). BRTB, the most effective bacterial strain, prevented completely the development of the pathogen. Based on the application time of BRTB, infection was not observed on seedlings on growing from tubers inoculated with pathogen 4?h after dipping into the bacterial solution. In storage treatments, BRTB was the most efficacy isolate when compared with others. As a result, BRTB strain of Pantoea agglomerans can be candidate in the biological control of F. oxysporum.

     

Volatile organic compounds in watermelon (Citrullus lanatus) grafted onto 21 local and two commercial bottle gourd (Lagenaria siceraria) rootstocks

Summary

Volatile organic compounds (VOCs) are responsible for flavour development in watermelon (Citrullus lanatus). The objective of this study was to investigate the rootstock effects of 21 local bottle gourd [Lagenaria siceraria (Molina) Standl.] accessions collected from the Mediterranean region (Turkey) on the concentrations of VOCs in watermelon over 2 years. The watermelon cultivar ‘Crimson Tide’ was used as the scion and two commercial bottle gourd rootstocks were also used for comparison. The VOCs in each rootstock-scion combination were analysed using static headspace (SHS) and gas chromatography-mass spectrometry (GC-MS). A total of 24 VOCs were identified in watermelon fruit, including 11 aldehydes, seven alcohols, four ketones, one heterocyclic compound, and one acid. Acetaldehyde (25.9 – 39.5% of the total peak areas), propanal (5.0 – 8.3%), 2-propanone (2.5 – 4.9%), pentanal (2.1 – 3.6%), hexenal (14.5 – 22.6%), (E)-2-hexenal (0.4 – 2.3%), 6-methyl-5-hepten-2-one (10.0 – 19.05%), nonanal (1.6 – 4.4%), (Z)-6-nonenal (4.0 – 9.8%), (E)-2-nonenal (0.6 – 2.0%), (E,Z)-2,6-nonadienal (2.1 – 3.7%), (Z)-6-nonenol (1.0 – 3.2%), and (E,Z)-3,6-nonadienol (1.0 – 3.7%) were the most abundant VOCs found in all watermelon scions. There was no significant effect (P ≥ 0.05) of rootstock on the concentrations of acetaldehyde, propanal, pentanal, heptanal, ethanol, 1-pentanol, 2-propanone, 2-pentyl furan, or acetic acid. Propanal, 2-propanone, and acetic acid were identified as VOCs in watermelon for the first time. Hexanal, (Z)-6-nonanal, and 6-methyl-5-hepten-2-one concentrations were strongly affected by rootstock. The results showed that the local bottle gourd accessions 07-06 and 31-09, in particular, were the most promising genotypes in terms of producing favourable VOCs. Except for the local bottle gourd accessions 33-35, 01-17, and 07-04, the other 18 gourds accessions had high potential as rootstocks for breeding programmes in watermelon with regard to desirable VOC concentrations. Rootstock 31-09 should be considered for commercial production in terms of improved disease resistance, fruit yield, and fruit quality.     

Some Physicochemical Characteristics,Bioactive Content and Antioxidant Characteristics of Non-Sprayed Barberry (Berberis vulgaris L.) Fruits from Turkey

Increasing consumer demands for indigenous, non-sprayed with pesticides and less-known or “forgotten” fruits necessitate knowledge on their breeding, cultivation, biochemical content, harvesting and marketing. Anatolia is rich for wild edible fruit species and barberry is abundant throughout Anatolia. The aim of this study was to determine some important physicochemical characteristics, bioactive content and antioxidant capacity of fruits from nineteen promising barberry (Berberis vulgaris L.) genotypes grown in the Coruh valley, Northeastern Anatolia. The results indicated genotype-specific differences for most of the physicochemical characteristics, antioxidant capacity and the content of some bioactive compounds. Fruit mass ranged from 0.073 (‘Coruh-7’) to 0.267 g (‘Coruh-11’). Total phenolic content ranged from 2532 (‘Coruh-’) to 3719 mg GAE per liter fruit juice (‘Coruh-11’). The genotype ‘Coruh-12’ had the highest total monomeric anthocyanin content (1004 mg per liter fruit juice) as cyanidin-3-glucoside. The highest total antioxidant capacity was observed in fruits of ‘Coruh-8’ and ‘Coruh-9’ genotypes with all three antioxidant-determining methods. We conclude that the barberry fruits represent a good source of bioactive phytochemicals because of their high phenolic and anthocyanin contents.     

Oxidative stress, steroid hormone concentrations and acetylcholinesterase activity in Oreochromis niloticus exposed to chlorpyrifos

We investigated the endocrine disrupting effects of chlorpyrifos-ethyl which is suspected to be originated from oxidative stress. Initially, the 96 h LC₅₀ values of chlorpyrifos in juvenile and adult of Oreochromis niloticus were determined to be 98.67 μg/L and 154.01 μg/L, respectively. Sub-lethal concentrations of chlorpyrifos-ethyl (5 ppb, 10 ppb, 15 ppb) were administrated to adult fish for 15 and 30 days. Fish were then left to depurate for 15 days in pesticide-free water. Gonadal somatic indices, serum sex steroids as indicators of reproductive function and cortisol level as indicator of stress condition were measured to observe the endocrine disruption effects of chlorpyrifos-ethyl. Gonadal glutathione S-transferase and antioxidant enzyme activities and lipid peroxidation as indicators of oxidative stress were also measured. Acetylcholinesterase activity was measured as a marker of chlorpyrifos toxicity. Results showed that serum estradiol, testosteron and cortisol levels in fish exposed to chlorpyrifos were lower than those of the control fish while gonad somatic indices did not change during the experiments. After 30 days, chlorpyrifos exposure decreased GST activity, and increased SOD enzyme activity by up to 215-446% compared with the control, suggesting there was a oxidative stress. No statistically significant differences between GPx and CAT specific activities, protein contents and lipid peroxidation were determined between control and treatment groups in all exposure concentrations and periods. Acetylcholinesterase activity decreased (45.83-77.28%) in gonad tissues. After recovery serum estradiol and testosteron levels were similar to those of the control levels. An increase in the GST and SOD enzyme activities were determined. Cortisol level and AChE activity in all exposure groups decreased after the depuration period, and fish were unable to overcome the stress of chlorpyrifos. Thus, this study revealed that after chlorpyrifos treatments there exists a protective function of antioxidant enzymes against lipid peroxidation in gonad tissue of O. niloticus. There also exist lower testosteron and estradiol levels in exposed fish than those of the control fish without any alterations in oxidative stress, which is attributed to the capability of chlorpyrifos to impair steroid hormone levels.