Optimization of Microwave-Assisted Extraction Procedure to Determine Metal in Fish Muscles Using Box–Behnken Design

This study describes the application of response surface methodology (RSM) to develop a method for zinc, lead, manganese, nickel, iron, and copper determination by flame atomic absorption spectrometry in Snow trout (Schizothorax zarudnyi) samples after extraction by a microwave system. The effects of various parameters such as irradiation power, temperature, extraction time, and concentration of nitric acid were investigated by a fractional factorial design (2⁴⁻¹) to determine the significant parameters and their interactions. The results showed that all of the parameters were significant (p < 0.05). The RSM, based on Box–Behnken design, was employed to obtain the optimum conditions of the significant parameters. The optimal conditions could be obtained at a power of 685.0 W, temperature of 116 °C, extraction time of 38.0 min, and 2.5 (mol L⁻¹) for nitric acid concentration. The method was applied for determination of zinc, lead, manganese, nickel, iron, and copper in Snow trout (Schizothorax zarudnyi) samples.     

Optimization of Microwave-Assisted Extraction Procedure for Zinc and Iron Determination in Celery by Box–Behnken Design

This article describes the development by response surface methodology (RSM) of a procedure for zinc and iron determination by flame atomic absorption spectrometry (FAAS) in food samples after extraction by microwave system. A Box–Behnken matrix was used to find optimal conditions for the procedure through response surface study. Three variables “irradiation power and time and temperature” were regarded as factors in the optimization study. The working conditions were established as a compromise between optimum values found for each analyte. These values were 80 °C, 105 W, and 9.0 min, for temperature, irradiation power and time, respectively. The method was applied to the determination of iron and zinc in two celery samples.     

Determination of Free Amino Acids in Coated Foods by GC–MS: Optimization of the Extraction Procedure by Using Statistical Design

The development and validation of an extraction procedure for quantification of free amino acids in coated products by MTBSTFA derivatization and GC–MS detection is described. The extraction method entailed the sample homogenization with hydrochloric acid (HCl) by stirring at 40 °C followed by two centrifugation steps. The optimum combination of the extraction variables was achieved by response surface methodology. HCl concentration and volume and stirring time influenced free amino acid extraction yield. The selected optimal extraction conditions were 5 g of sample mixed to 7.5 ml of 0.1 N HCl and stirred during 90 min. Consistency between predicted and experimental values as well as in the quality parameters was observed. The calibration curves were linear within the range 5–100 μg ml^?1 with correlation coefficient values (R ² ) higher than 0.99. Detection and quantification limits of the analytical procedure ranged from 2.10^?5 to 18.10^?2 μg μl^?1 and from 8.10^?5 to 60.10^?2 μg μl^?1, respectively. Precision was 0.20–12.59 % for run-to-run and 3.38–17.60 % for day-to-day. The accuracy is between 82.99 and 115.77 %. Nineteen amino acids were analyzed in frozen-thawed and deep-fried coated products from different origin, with cysteine being the most relevant.     

Optimization of Wool Slenderizing Along with In-situ Synthesis of Silver Nanoparticles Using Box–Behnken Design

Following our previous research for simultaneous in-situ synthesis of silver nanoparticles and wool fiber fineness using sulfur-based reducing agents, here we focused on optimization of the process using response surface methodology. A Box–Behnken Design was applied to study the influence of variables including silver nitrate percentage, reducing agent concentration, temperature and time of the procedure, and their appropriate values for the highest fineness, lowest tenacity reduction and lowest color change were obtained. Here we tried to optimize the preparation conditions using a weak reducing agent namely sodium bisulfite to achieve the equivalent fineness modification but with reduced fiber damage.     

Application of Box–Behnken Design in the Optimization of In Situ Surfactant-Based Solid Phase Extraction Method for Spectrophotometric Determination of Quinoline Yellow in Food and Water Samples

In this work, a simple, rapid and sensitive method using in situ surfactant-based solid phase extraction (ISS-SPE) combined with UV–vis spectrophotometry has been developed for the preconcentration and determination of trace amounts of quinoline yellow in food and water samples. The Box–Behnken design was employed to optimize the extraction efficiency. The variables of interest were pH, surfactant volume, extraction time and NaI volume. In the optimal conditions, the calibration graph was linear in the range of 10.0–750 μg L^?1 with a correlation coefficient of 0.9982. The limit of detection (LOD) was 2.1 μg L^?1, and the preconcentration factor was calculated to be 51.8.     

Determination of Thiamine in Wheat Flours Using a Validated Isocratic HPLC-Fluorescence Method Previously Optimized by Box–Behnken Design

The main purpose of this work was to optimize and validate a new isocratic high-performance liquid chromatography method for thiamine analysis in wheat flours. Thiamine was previously derivatized into thiochrome and determined by fluorescence detection (excitation wavelength, 366 nm; emission wavelength, 435 nm). The mobile phase consisted of buffer phosphate (0.02 M) and organic modifier (methanol 88 %; acetonitrile 12 %). Optimization was done using a Box–Behnken design (three factors at three levels) where organic modifier proportion (A), varying from 20 to 90 %, mobile phase pH (B), varying from 5.8 to 7.8, and flow rate (C), varying from 0.5 to 1 mL min^?1, were the studied variables. Peak width was the studied response. Optimal chromatographic conditions that minimized response were A?=?90 %, B?=?6.00, and C?=?1 mL min^?1. Using optimal conditions, thiochrome extractions with isobutanol and solid-phase extraction (SPE) employing styrene-divinylbenzene adsorbent cartridges were compared. Method validation, using thiamine standard solutions and both types of thiochrome isolation, included linearity studies, limits of detection and quantification, and calibration and analytical sensitivity quantifications. Standard addition method was employed to quantify thiamine in wheat flours. Good precision results were obtained by both extraction methods. Recoveries ranged from 63 to 65 % for isobutanol and 84 to 101 % for SPE, including sample extraction, thiamine derivatization, thiochrome purification, and chromatographic separation. Taking into account better obtained SPE recoveries, acceptable precision, and isobutanol irritant action on the eyes and skin of operator, SPE using styrene-divinylbenzene adsorbent could be chosen for routine thiamine analysis in wheat flour samples.     

Ultrasound-Assisted Extraction Followed by Solid-Phase Extraction Followed by Dispersive Liquid–Liquid Microextraction for the Sensitive Determination of Diazinon and Chlorpyrifos in Rice

Selectivity of solid-phase extraction (SPE) was combined with the concentration power of dispersive liquid–liquid microextraction (DLLME) to obtain a sensitive, low solvent consumption method for high-performance liquid chromatography determination of diazinon and chlorpyrifos in rice. In this method, rice samples were extracted by ultrasound-assisted extraction followed by SPE. Then, the SPE eluent was used as a disperser solvent in the next dispersive liquid-liquid microextraction step for further purification and enrichment of diazinon and chlorpyrifos. Under the optimal conditions, the linear range was from 5.0 to 250 μg kg^?1 for diazinon and from 2.5 to 250 μg kg^?1 for chlorpyrifos. Limits of detection of diazinon and chlorpyrifos were 1.5 and 0.7 μg kg^?1, respectively. Limits of quantitation of diazinon and chlorpyrifos were 5.5 and 3.0 μg kg^?1, respectively. The precisions and recoveries also were investigated by spiking 10 μg kg^?1 concentration in rice. The recoveries obtained were over 90 % with relative standard deviation (RSD%) below 9.0 %. The new approach was utilized to successfully detect trace amounts of diazinon and chlorpyrifos in different Iranian rice samples.     

A Box–Behnken Design for Determining the Optimum Experimental Condition of Cake Batter Mixing

The application of Box-Behnken design to establish the optimum experimental condition of cake batter mixing is important because optimal mixing can ensure the dispersion of ingredients, and the incorporation and retention of air efficiently. A Box-Behnken with three factors such as mixing time, mixing speed, and cake loading was selected to observe the effects on batter density, cake density, hardness, springiness, cohesiveness, gumminess, chewiness, and resilience. The mixing times ranged from 6 to 20 min, mixing speeds from 90 to 120 rpm, and cake loadings from three to five cakes. A total of 15 runs of experiments where three levels attributed to each factor at high, central and low, and with additional three replicated center points were conducted. Using goal settings for each response based on quality parameters attained from the best definition of each response to achieve high cake quality, an optimum and feasible experimental condition of batter mixing was obtained at 9 min of mixing time, 90 rpm of mixing speed, and three cakes loading.     

Analysis of Cheese Small Molecules by UPLC–QToF-MS and Multivariate Statistical Methods Using Several Extraction Procedures

Lyophylized (L) and nonlyophylized (NL) samples of two cheeses from different batches were extracted with either methanol:water (8:2, v/v) or isopropanol:water (7:3, v/v), and the extracts were analyzed by ultraperformance liquid chromatography coupled with electrospray ionization/quadruple-time-of-flight mass spectrometry (UPLC–ESI–QToF-MS) in both positive and negative modes. Chromatographic and mass spectrometric data were further compared for different samples by paired t test and principal component analysis (PCA). Mass spectra at different elution times were manually checked and major peaks tentatively identified according to their m/z values by search in available databases. A number of gangliosides and polyglycosilated ceramides were found to be the most abundant components. PCA showed samples could be clustered according to extraction procedure and cheese, and paired t test comparison also showed significant (p?<?0.05) differences between L and NL samples extracted with methanol:water. L and NL samples could only be distinguished in PCA when data from the whole chromatographic range were used. Results are discussed based on extraction solvent polarity and feasibility of PCA for comparison of cheese chemical composition after untargeted UPLC–MS analysis.     

Response surface modelling of lead pre-concentration from food samples by miniaturised homogenous liquid–liquid solvent extraction: Box–Behnken design

In this study, a new method called miniaturised homogenous liquid–liquid extraction, followed by graphite furnace atomic absorption spectrometry, was developed for the extraction and determination of lead from food samples. The procedure was based on the fast extraction of lead from an acetic acid sample solution into 0.5 mL chloroform, as an extraction solvent. After adding water into the mixture, the extracting solvent phase immediately formed a distinct water-immiscible phase below the vial, which could easily be separated, evaporated and re-dissolved in 1.0 mL nitric acid 0.1 mol L⁻¹ for further analysis. The effects of various experimental parameters in extraction step were studied using two optimisation methods, one variable at a time and Box–Behnken design. The results showed that the amount of salt and extraction time did not have effect on the extraction efficiency. Therefore, a three-level Box–Behnken experimental design with three factors, which combined the response surface modelling, was used to optimise lead extraction. Three independent variables, including pH of solution (ranging from 6.5 to 10.5), concentration of dithizone as chelating agent (ranging from 0.05 to 0.5 μg L⁻¹) and extracting solvent volume (ranging from 300 to 900 μL) were respectively coded as pH, D and V at three different levels (−1, 0 and 1). In this study, the optimum condition was determined at pH 8.4, a volume of chloroform at 0.45 mL, and concentration of dithizone at 0.5 μg L⁻¹. Under the optimum condition, the limit of detection (LOD) was 0.05 μg L⁻¹. Furthermore, the relative standard deviation of the ten replicate was <5.0%. The developed procedure was applied to the extraction and determination of lead in the food samples.     

Extraction and Preconcentration of Some Triazole Pesticides in Grape Juice by Salting Out Homogeneous Liquid–Liquid Extraction in a Narrow-Bore Tube Prior to Their Determination by Gas Chromatography–Flame Ionization Detection

A fast and simple extraction and preconcentration method for some triazole pesticides has been developed using a homogeneous liquid–liquid extraction method performed in a narrow-bore tube. The extraction is based on phase separation of a water-miscible organic solvent from aqueous solution in the presence of a salting out agent. In this work, the homogeneous solution of water and acetonitrile (water-soluble extraction solvent) was broken by addition of 30 %, w/v, sodium chloride (salting out agent). After sonication, a small volume of acetonitrile was collected on top of the tube and the extracted analytes in the collected phase were determined by gas chromatography–flame ionization detection. The effect of various experimental parameters including kind and volume of the water-soluble organic solvent, amount of salt, length and diameter of tube, and pH of sample solution was investigated. Under the optimum conditions, calibration graphs were linear over the range of 3–5,000 μg L^?1. Relative standard deviations were less than 5.4 % for six repeated determinations (C?=?100 μg L^?1). Furthermore, the limits of detection (S/N?=?3) and quantification (S/N?=?10) were obtained in the ranges of 0.60–4.8 and 1.9–16 μg L^?1, respectively. This method is very simple and rapid, requiring less than 10 min for sample preparation. It has been successfully utilized for the analysis of triazole pesticides in the grape juice samples.     

Development of Multiresidue Analysis for 21 Synthetic Colorants in Meat by Microwave-Assisted Extraction–Solid-Phase Extraction–Reversed-Phase Ultrahigh Performance Liquid Chromatography

A novel ultrahigh performance liquid chromatographic method is developed for analysis of 21 synthetic colorants with different acid–base property, solubility, and polarity. The meat samples were extracted by microwave-assisted extraction followed by cleanup with solid-phase extraction. The effective separation of the colorants in meat matrixes was achieved, and no interfering peaks could be detected at the retention time of the analytes. The calibration curves showed good linearity with correlation coefficients of 0.9940–0.9999. The limits of quantification were 0.48–7.19 μg/kg. The average recovery of the 21 analytes from meat samples spiked with 25 and 75 μg?kg^?1 was 61.29–116.1 % with relative standard deviation (RSD) of <11 %. For blank beef sausage spiked with 50 μg?kg^?1 for each analyte, the intraday precision (as RSD) for 21 analytes was 1.45–9.21 % for six determinations within a day. This method has the advantages of being rapid, sensitive, accurate, and with high-throughput and can be applied for multiresidue analysis of meat samples, including six allowable azo food colorants, ten banned azo food colorants, four banned triphenylmethanes, and rhodamin B food colorant.     

A Simple and Selective Analytical Procedure for the Extraction and Quantification of Lutein from Tomato By-Products by HPLC–DAD

Lutein, a yellow dihydroxylated carotenoid, is present in many dietary supplements due to its biological properties. Currently, lutein is extracted from marigold flowers by expensive and time-consuming processes. Since tomatoes contain significant levels of lutein, in this study we have examined the feasibility of using tomato by-products as an alternative, low-cost source of this carotenoid. The determination of this carotenoid was performed by high-performance liquid chromatography–diode array detection, after selective extraction from tomato waste product samples. Lutein levels ranged from 9.9 to 10.5 μg/g dry weight. Tomato waste products may be indicated as an alternative commercial source of lutein for food fortification and/or dietary supplements.     

One-Step QuEChERS-Based Approach to Extraction and Cleanup in Multiresidue Analysis of Sulfonylurea Herbicides in Cereals by Liquid Chromatography–Tandem Mass Spectrometry

A one-step quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based approach to extraction and cleanup in multiresidue pesticide analysis is presented for the first time. The experiment was designed to detect 23 sulfonylurea herbicides in a complex cereal matrix. The challenge was to choose the optimal conditions of one-step extraction and cleanup. Chitin, diatomaceous earth, and octadecyl were investigated as cleanup sorbents. Chitin, citrate buffer, and 1 % formic acid in acetonitrile yielded the best results. The effectiveness of sulfonylureas extraction was evaluated at three different spiking levels (0.005, 0.05, and 0.5 mg kg^?1) in wheat, rye, and oat using liquid chromatography–tandem mass spectrometry. The one-step QuEChERS provided recoveries in the 70–120 % range for 23 sulfonylureas in all cereal matrices. Matrix effects were evaluated and were not significant for all herbicides, showing suppression or enhancement (between ?19 and 13 %). Precision, calculated as relative standard deviation (RSD), was below 20 %. A linear dependence was observed in the range of 0.005–2.0 mg kg^?1, and the correlation coefficient was R ² > 0.999. Expanded measurement uncertainty was estimated to be between 9 and 24 %, on average. The validated method was employed in analysis of 89 real grain samples.