A New Enrichment Method for Quantification of 5-Hydroxymethylfurfural by Indirect Flame Atomic Absorption Spectrometry in Honey and Jam Samples

Background Because of increasing amounts of 5-hydroxymethylfurfural (5-HMF) in processed foods and the complexity of the matrix, monitoring of trace 5-HMF requires accurate and reliable methods. Hence, an efficient sample pretreatment procedure is necessary for extraction and preconcentration of 5-HMF from the matrix. Objective In this study, a new and efficient sample preparation method utilizing ultrasound-assisted-cloud point extraction (UA-CPE), indirectly followed by flame atomic absorption spectrometry (FAAS), was introduced for the monitoring of trace amounts of 5-HMF in honey and jam samples. Methods With this method, hydroxylamine was used as a derivatizing agent in the presence of Mn(II) and an anionic surfactant, SDS for extraction of 5-HMF at pH 9.0. For dispersing reagents in sample solution, low amounts of mixed surfactant, triton X-45 and SDS were mixed and fast-injected into the extraction media. A cloudy solution formed, and after reaction of 5-HMF with reagents, the cloudy solution was centrifuged. The extracted 5-HMF in the surfactant-rich phase was dissolved in acidic acetone and indirectly analyzed by FAAS. Results The method showed a detection limit of 1.27 μg/L in linear working range of 4–240 μg/L, good precision (2.3–6.5%), and recovery rates (93.5–97%) after preconcentration of 70-fold. Conclusions Within this study, an accurate and reliable method for the indirect quantification of 5-HMF in selected samples was successfully developed with a sensitivity improvement factor of 30.6. Highlights The figures of merit for the developed indirect method were appropriate. The applicability of the method for the analysis of 5-HMF in processed foods was excellent.

Cloud point-dispersive liquid-liquid microextraction for preconcentration and determination of mercury in wastewater samples by methylsulfanyl thiophenol material

A efficient method based on 4-methylsulfanyl thiophenol (MSTP, C7H8S2) and ionic liquid ([BMIM][PF6]) was used for mercury (Hg) separation and preconcentration from wastewater of petrochemical industries. The 0.01 mile molar of MSTP, 80 mg of [BMIM][PF6] was diluted with 0.2 mL of ethanol (ET 98%). The mixture was injected to 10 mL of wastewater samples, shacked by ultrasonic bath for 5.0 min and cloudy solution was achieved by ionic liquid micelles at pH=7.0. The mercury ions was complexed with MSTP and extracted on micelles (IL/ET) by cloud point dispersive liquid-liquid microextraction (CP-DLLME) at 50oC before determined by cold vapor atomic absorption spectrometry (CV-AAS). The favorite extraction for mercury with low LOD (15 ng L-1) and good linear rages (0.05- 6.2 μg L-1) was achieved (RSD<5%). The main parameters such as, pH, sample volumes, amount of MSTP, amount of IL and ultra-sonic time were optimized.

Development of a New and Fast Extraction Method Based on Solvent-Assisted Dispersive Solid-Phase Extraction for Preconcentration and Trace Detection of Atrazine in Real Matrices

Background: Because of trace amounts of atrazine in water samples and the complexity of the matrix, direct trace monitoring of atrazine is not feasible by the abovementioned techniques. Hence, an efficient sample pretreatment procedure is necessary for cleanup and preconcentration of atrazine from sample matrices. Objective: In the current paper, a new and efficient sample preparation method named solvent-assisted dispersive solid-phase extraction (SA-DSPE), followed by HPLC–UV, was introduced for the monitoring of atrazine at trace levels in environmental water samples. Methods: In the present method, benzophenone was used as a sorbent for extraction of target molecules. For dispersing solid sorbents in sample solution, very low milligram amounts of benzophenone and dispersive solvent were mixed and fast-injected into the extraction media. A cloudy solution formed, and after interaction of atrazine and the dispersed solid sorbent, the cloudy solution was centrifuged. The extracted atrazine in the solid phase was dissolved in ethanol and analyzed by HPLC–UV. Results: The introduced method showed a low method detection limit (0.1 μg/L), good precision (relative SD: 3.9–6.9%), and appropriate relative recoveries (95–105%). Conclusions: Within this study, a sensitive and reliable method for the quantification of atrazine in wastewater samples was successfully developed. Highlights: The obtained figures of merit for the presented sample preparation method were appropriate. The applicability of the method for analysis of atrazine in real matrices was excellent.

β-Cyclodextrin Assisted Liquid–Liquid Microextraction Based on Solidification of the Floating Organic Droplets Method for Determination of Neonicotinoid Residues

An efficient and environment-friendly microextraction method, namely, β-cyclodextrin assisted liquid–liquid microextraction, based on solidification of the floating organic droplets method coupled with HPLC is investigated for the sensitive determination of trace neonicotinoid pesticide residues. In this method, β-cyclodextrin is used as a disperser solvent, while 1-octanol is selected as an extraction solvent. β-cyclodextrins was found to decrease interfacial tension and increase the contact area between the organic and water phases with the help of centrifugation. A cloudy solution was rapidly formed and then centrifuged to complete phase separation. Various key parameters influencing extraction efficiency were systematically investigated and optimized; they include salt addition, concentration of β-cyclodextrin, and volume of extraction solvent (1-octanol). Under optimum conditions, good linearity was obtained with coefficient for determination (R2) greater than 0.99. A low limit of detection, high enrichment factor, and good recovery (83 – 132) were achieved. This proves that the proposed method can be applied to determine trace neonicotinoid pesticide residues in natural surface water samples.

Extraction and Determination of Trace Amounts of p-Coumaric Acid in Vinegar, Carrot Juice, and Seed Extract from Silybum marianum (L.) Gaertn

In this study, for the monitoring and quantification of p-coumaric acid (p-CA) in vinegar, carrot juice, and seed extract from the plant species Silybum marianum (L.) Gaertn, an efficient and low-cost analytical method has been applied. For this purpose, a dispersive liquid–liquid microextraction (DLLME) method, followed by UV-Vis spectrophotometric detection, was used. To form a cloudy solution, a binary mixture containing ethanol as a disperser solvent and chloroform as an extraction solvent was rapidly injected by syringe into a sample solution containing p-CA. After centrifugation, dilution of the obtained organic phase was done with the proper amount of ethanol, and the phase was transferred into a micro cell for subsequent measurement. Some effective parameters for the DLLME method, such as the volume of disperser solvent and extraction solvent, pH, and salt concentration were inspected by a 24 full factorial central composite design using design Export Software. Under the optimized conditions, linearity was between 10 and 150 ng/mL, and the LOD was 2.3 ng/mL. The results of the proposed method were similar to the obtained results using a GC with flame-ionization detection method.

Preconcentration of nickel in waters by vortex assisted dispersive liquid-liquid microextraction

The present work describes the attempt for the preconcentration of nickel ions by using vortex assisted dispersive liquid-liquid microextraction from aqueous samples. In this method, a small amount of chloroform is rapidly injected by syringe into the water sample containing nickel ions complexed by diethyldithiocarbamate (DDTC).This forms a cloudy solution. The cloudy state is the result of chloroform fine droplets formation, which are dispersed in bulk aqueous sample. Therefore, Ni-DDTC complex is extracted into the fine chloroform droplets and vortex agitation takes place during six minutes. After optimization of experimental variables and determination of analytical characteristics, the method is evaluated for application in real samples. HPLC is used as separation and detection system.

Biodiesel as a Plasticizer of a SBR-Based Tire Tread Formulation

The solubility parameter of a series of methyl esters of fatty acids, the components of biodiesel, was calculated using the group incremental method proposed by Van Krevelen. The solubility parameter of biodiesel was compared with that of a series of rubbers like EPDM, butyl rubber, polyisoprene, polybutadiene, SBR (with different content of styrene), and nitrile rubber (with different content of acrylonitrile) showing that biodiesel is an effective solvent of all the above mentioned rubbers with the exclusion of nitrile rubber. Indeed, it was experimentally verified that polyisoprene, polybutadiene and SBR are easily soluble in biodiesel while polystyrene gives a cloudy solution. Considerations on the solubility parameter of the biodiesel and of a series of rubbers have led to the conclusion that biodiesel behaves essentially as an internal lubricant in a diene rubber matrix, the same situation occurs with the common aromatic mineral oil plasticizer known as T-RAE. The experimental evaluation of biodiesel as plasticizer in an SBR-based rubber compound in comparison to an aromatic mineral oil have led to the primary conclusion that biodiesel is reactive with the sulphur curing agent subtracting sulphur to the crosslinking polymer chains and leading to a vulcanizatewith lower moduli, tensile and hardness and higher elongationsin comparison to a reference compound fully plasticized with an aromatic mineral oil. However, biodiesel seems a good low temperature plasticizer because the low elastic modulus observed is desired in a winter tire tread for a good grip on snow and ice. The present work is only an exploratory work, and the tire tread formulation with biodiesel was not optimized.

Field Determinations of Pentachlorophenol in Water Using UV/Vis Spectroscopy

Pentachlorophenol (PCP) is an organochloride pesticide banned in many countries due to its broad-spectrum toxicity. Current methods for monitoring PCP in environmental water require expensive laboratory equipment, limiting field monitoring. Two field methods for screening the concentration of PCP in environmental water are described herein. The first involves filtering the sample and calculating the indicative concentration from the absorbance at 320 nm. Alternatively, the sample can be acidified with concentrated hydrochloric acid to produce a fine suspension. This cloudy solution can be matched to a photo card for field estimation of concentration, or calculated more accurately from the absorbance at 450 nm. The useable ranges for these methods are 2 ppb to 100 ppm for the un-acidified method and 4 ppm to 1000 ppm for the acidified method. Results indicate that aquatic humic substances and natural turbidity present in environmental water do not compromise the results.