Validation of an analytical method for determination of 13 priority polycyclic aromatic hydrocarbons in mineral water using dispersive liquid-liquid microextraction and GC-MS

Dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography–mass spectrometry (GC–MS) was used for the extraction and determination of 13 polycyclic aromatic hydrocarbons (PAHs) in mineral water samples. In this procedure, the suitable combination of extraction solvent (500 μL chloroform) and disperser solvent (1000 μL acetone) were quickly injected into the water sample (10.00 mL) by Hamilton syringe. After centrifugation, 500 μL of the lower organic phase was dried under a gentle stream of nitrogen, re-dissolved in chloroform and injected into GC-MS. Chloroform and acetone were found to be the best extraction and disperser solvent, respectively. Validation of the method was performed using spiked calibration curves. The enrichment factor ranged from 93 to 129 and the recovery ranged from 71 to 90%. The linear ranges for all the PAHs were 0.10-2.80 ngmL-1. The relative standard deviations (RSDs) of PAHs in water by using anthracene-d10 as internal standard, were in the range of 4-11% for most of the analytes (n = 3). Limit of detection (LOD) for different PAHs were between 0.03 and 0.1 ngmL-1. The method was successfully applied for the analysis of PAHs in mineral water samples collected from Tehran. © 2016 by School of Pharmacy Shaheed Beheshti University of Medical Sciences and Health Services

Determination of benzoapyrene in traditional, industrial and semi-industrial breads using a modified QuEChERS extraction, dispersive SPE and GC-MS and estimation of its dietary intake

A fast and simple modified QuEChERS extraction method was developed for determination of Benzo[a]pyrene (BaP) in 137 traditional (Sangak), semi-industrial (Sangak) and industrial bread samples using spiked calibration curves by GC/MS. Sample preparation includes extraction of BaP into acetone followed by cleanup with dispersive solid phase extraction. The limit of detection and limit of quantification were 0.3 ng/g and 0.5 ng/g, respectively. The values for recoveries and RSD were calculated as 110.5-119.85% and 1 ng/g. BaP content in all industrial samples was lower than LOQ. Assuming the consumption of bread in Tehran and Shiraz is limited to these kinds of breads, the daily intake of BaP in Tehran and Shiraz population through bread consumption was estimated to be 170.6 and 168.7 ng/day, respectively. This is the first report concerning contamination of bread samples with BaP in Iran

Validation of an Analytical Method for Determination of Benzoapyrene Bread using QuEChERS Method by GC-MS

A fast and simple modified QuEChERS (quick, easy, cheap, rugged and safe) extraction method based on spiked calibration curves and direct sample introduction was developed for determination of Benzo[a]pyrene (BaP) in bread by gas chromatography-mass spectrometry single quadrupole selected ion monitoring (GC/MS-SQ-SIM). Sample preparation includes: extraction of BaP into acetone followed by cleanup with dispersive solid phase extraction. The use of spiked samples for constructing the calibration curve substantially reduced adverse matrix-related effects. The average recovery of BaP at 6 concentration levels was in range of 95-120%. The method was proved to be reproducible with relative standard deviation less than 14.5% for all of the concentration levels. The limit of detection and limit of quantification were 0.3 ng/g and 0.5 ng/g, respectively. Correlation coefficient of 0.997 was obtained for spiked calibration standards over the concentration range of 0.5-20 ng/g. To the best of our knowledge, this is the first time that a QuEChERS method is used for the analysis of BaP in breads. The developed method was used for determination of BaP in 29 traditional (Sangak) and industrial (Senan) bread samples collected from Tehran in 2014. These results showed that two Sangak samples were contaminated with BaP. Therefore, a comprehensive survey for monitoring of BaP in Sangak bread samples seems to be needed. This is the first report concerning contamination of bread samples with BaP in Iran. © 2016 by School of Pharmacy

Development and Validation of a Rapid Derivative Spectrophotometric Method for Determination of Tropicamide in Eye Drops: Determination of tropicamide in eye drops

Tropicamide is an antimuscarinic agent used as eye drops for refractive examinations. The aim of this study was to develop a simple and suitable analytical method for determination of tropicamide in eye drops in the presence of excipients. A zero-crossing third and fourth derivative spectrophotometric method was described for determination of tropicamide in eye drops. The measurements were carried outat wavelengths of 263.8 and 255.4 nm for third- and fourth-derivative, respectively. The method was found to be linear (r2> 0.999) in the range of 10-100 µg/ml for tropicamide in the presence of excipients. The limit of determination was 10 mg/ml for tropicamide. The method was successfully applied for determination of tropicamide in eye drops without any interference from excipients or need to prior separation before analysis

Screening Pseudomonas fluorescens strains for plant growth promoting properties and salinity tolerance

Introduction:Plant growth-promoting rhizobacteria (PGPR) are a group of plant rhizosphere inhabitants bacteria which stimulate plant growth and increase host tolerance to environmental stresses using several mechanisms. Fluorescent pseudomonads are considered as the most important plant growth promoting rhizobacteria. The aim of this study is screening Pseudomonas fluorescens strains isolated from barley rhizosphere in Bushehr province for growth stimulating properties and tolerace to salt stre. Materials and methods: 25 P. fluorscens strains were evaluated for growth stimulating properties including siderophore, indole-3-acetic acid (IAA) and hydrogen cyanide (HCN) production, inorganic phosphate solubilization and the ability to tolerate salinity levels (0, 200, 400 and 600 mM of sodium chloride) under in vitro conditions. Results: The results revealed that among the 25 strains studied, all were siderophore-producers (1.34-8.48 µM/ml) and 88% were able to produce HCN. The ability to solubilize mineral phosphate was observed in 88% of strains. Superior strains with PGP traits (B2-10, B4-6, B10, P68 and CHA0) were able to produce IAA (1.78-2.29 mg/ml). All strains were able to tolerate NaCl concentrations of 200-600 mM, however, their colony diameter decreased with increase in salinity levels. Discussion and conclusion: The current study showed that some P. fluorescens strains isolated from barley rhizosphere like B2-10, B4-6, B2-11 and B10, had plant growth-promoting characteristics and salt tolerance ability, so it can be concluded that these strains have  the potential to be applied as useful microorganisms in bifertilizers to enhance plant growth under salt stress conditions

Growth promotion and yield enhancement of barley cultivars using ACC deaminase producing Pseudomonas fluorescens strains under salt stress

Plant growth-promoting rhizobacteria containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase enzyme reduce the level of stress, ethylene and stimulate plant growth under various biotic and abiotic stress conditions. The present study aims at characterizing efficient salt-tolerant, ACC deaminase containing Pseudomonas fluorescens strains with plant growth-promoting activity isolated from the rhizosphere of barley plants and evaluating the influence of potent plant growth-promoting rhizobacteria (PGPR) isolates on growth and yield of five barley cultivars under salinity stress. Plant growth and yield in barley cultivars following inoculation with salt-tolerant, ACC deaminase producing PGPR strains under salt stress were quantified. Results indicated that under various levels of salinity (50, 100 and 150 mM NaCl) inoculation with PGPRs had positive impact on growth parameters and yield of barley cultivars including plant height, spike length, weight and number, peduncle length, number of grains per spike, 1000-grain weight and grain yield, comparing to uninoculated control plants under salinity stress. Inoculation of barley cultivars with bacteria ameliorated the negative effects of salinity and resulted in increase in growth and yield. Besides, as the salinity levels increased, growth and yield of barley cultivars decreased; however, cultivars showed different responses to salt stress. This study demonstrates the vital role of rhizobacteria containing ACC deaminase for increasing salt tolerance and consequently improving the growth and yield of barley plants under salinity stress

Growth promotion and yield enhancement of barley cultivars using ACC deaminase producing Pseudomonas fluorescens strains under salt stress

Plant growth-promoting rhizobacteria containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase enzyme reduce the level of stress, ethylene and stimulate plant growth under various biotic and abiotic stress conditions. The present study aims at characterizing efficient salt-tolerant, ACC deaminase containing Pseudomonas fluorescens strains with plant growth-promoting activity isolated from the rhizosphere of barley plants and evaluating the influence of potent plant growth-promoting rhizobacteria (PGPR) isolates on growth and yield of five barley cultivars under salinity stress. Plant growth and yield in barley cultivars following inoculation with salt-tolerant, ACC deaminase producing PGPR strains under salt stress were quantified. Results indicated that under various levels of salinity (50, 100 and 150 mM NaCl) inoculation with PGPRs had positive impact on growth parameters and yield of barley cultivars including plant height, spike length, weight and number, peduncle length, number of grains per spike, 1000-grain weight and grain yield, comparing to uninoculated control plants under salinity stress. Inoculation of barley cultivars with bacteria ameliorated the negative effects of salinity and resulted in increase in growth and yield. Besides, as the salinity levels increased, growth and yield of barley cultivars decreased; however, cultivars showed different responses to salt stress. This study demonstrates the vital role of rhizobacteria containing ACC deaminase for increasing salt tolerance and consequently improving the growth and yield of barley plants under salinity stress