Optimization Of Method For Determination Research Articles

Optimization of QuEChERS method for determination of 315 pesticides residues: prelude to risk assessment using LC-ESI-MS/MS

Optimization of QuEChERS method for determination of 315 pesticides residues: prelude to risk assessment using LC-ESI-MS/MS

Optimization of Methods for Determination of the Encapsulation Efficiency of Doxorubicin in the Nanoparticles Based on Poly(lactic-co-glycolic acid) (PLGA)

Introduction . Drug encapsulation efficiency (EE) is the important parameter of the nanoparticle-based drug formulations. Generally, the methods for evaluation of the EE are based on separation of the free and NP-bound fractions of the drug; however, applicability of these methods for a particulate formulation needs careful consideration. Aim. The purpose of the study was to optimize the procedure for evaluation of the EE for a nanoparticle-based drug formulation taking doxorubicin loaded in the PLGA nanoparticles (PLGA-Dox NP) as a model formulation. Materials and methods. The PLGA-Dox NP were prepared by a “double emulsion” method at pH of the external aqueous phase of 7.4 or 6.4. The NP size and size distribution (PDI) were determined by photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM). For the EE evaluation of doxorubicin, the NP were separated by centrifugation (CF), ultrafiltration (UF), or gel filtration. The efficiency of NP separation by the CF method was evaluated by the PLGA content in the supernatant by capillary electrophoresis (CZE). Results and discussion. The average hydrodynamic diameter of the PLGA-Dox/7.4 and PLGA-Dox/6.4 NP (FCS) was 103 ± 10 nm and 141 ± 8 nm, respectively. According to the TEM data, the main fraction of the NP averaged 50 ± 16 nm. The EE of doxorubicin, determined after the NP separation by centrifugation at 48254.g, was 78.9 ± 1.8 % for the PLGA-Dox/6.4 and 91.5 ± 0.9 % for the PLGA-Dox/7.4 NP with the residual PLGA content in the supernatant of ~5 %. At lower acceleration the NP separation was incomplete leading to underestimation of the EE. Also, the ultrafiltration method using the filters with the NMWL of 50 and 100 kDa enabled the reliable NP separation with the minimal doxorubicin adsorption on the filter (<4 %). Separation of the NP by gel filtration led to the underestimation of the EE due to considerable desorption of doxorubicin from the NP surface. Conclusion. The optimal analytical procedures for evaluation of the EE of doxorubicin in the PLGA NP are based on the NP separation by CF at 48254×g and UF using filters with NMWL of 50 and 100 kDa.

Optimization of method for determination of Forsythia Fructus and discussion on the establishment of quality control standard for green (old) Forsythia Fructus

In order to obtain the optimum method for content determination of Forsythia Fructus (FF), a variety methods for the sample preparation of FF were evaluated by the content determination methods of Chinese Pharmacopoeia. And an optimum method was screened and as follows: 30 times with 70% ethanol solution in ultrasonic extractor for half an hour. The method can achieve the best effect of simultaneously extracting forsythoside A and forsythin. Then, a HPLC method for simultaneous determination of forsythoside A and forsythin was established by methodology. The HPLC chromatographic conditions: the mobile phase consisted of acetonitrile (A)-0.4% acetic acid solution (B) with gradient elution [0-33 min，15%A，33-43 min，15%-25%A，43-60 min，25% A] was at the flow rate of 1 mL·min⁻¹, the column temperature was 25 °C, and the detection wavelength was 330 and 277 nm. Moreover, the contents of forsythoside A and forsythin for 10 Green Forsythia Fructus (GF) and 5 Old Forsythia Fructus (OF) were determined by this method and Chinese Pharmacopoeia. The result not only displayed that the established method is effective, rapid, and simple, but also showed that the contents of forsythoside A and forsythin for GF and OF were significantly different. Which implied that the forsythoside A and forsythin limit standard for GF and OF should be controled by different values. This studies provide an important basis for the establishment of the content determination of FF and the quality control standard for GF and OF.

Optimization of an Analytical Method for Determination of Pyrene in Smoked Meat Products

In the present study, an analytical method was optimized for determination of pyrene by solid-phase extraction in Turkish foodstuffs including chicken and grilled meat samples. In accordance with this purpose, all of the parameters that may affect the signal of pyrene during analysis processes were optimized using high-performance liquid chromatography–mass spectrometry system. The optimized parameters for column temperature, injection volume, mobile-phase flow rate, and fragmentor potential were found to be 45 °C, 60 μL, 0.6 mL min−1, and 130 V, respectively. The optimized high-performance liquid chromatography–mass spectrometry method was applied for the determination and evaluation of pyrene in food samples that include chicken and grilled meat. The pyrene amount in meat samples was obtained in the range from 2.3 to 4.4 μg kg−1 for the normal grilled meat and chicken samples and from 12 to 135 μg kg−1 for exceedingly grilled samples. The results show that the concentration of pyrene is significantly dependent on the type of meat sample and cooking source. The limit of detection and quantitation was found to be 0.5 μg L−1 and 1.53 μg L−1, respectively.

Optimization of Method for Determination of Swelling Factor of Ispaghula Seeds

An endeavour of present study is to optimize the method for determination of swelling factor of Ispaghula seeds, so it can be determined correctly with minimum errors which will be reproducible. The polysaccharides in the mucilage of Plantago seeds constitute a diverse class of biological macromolecules with a broad range of physiochemical properties which are widely used for applications in Pharmacy and medicine. Many official and unofficial sources described different methods for determination of swelling factor with variable results. The present work is undertaken to determine the effect of parameters such as quantity of seed, volume and nature of solvent, time interval of agitation, time of measurement of result, Effect of quantity of seeds on swelling factor determination. Swelling factor of different seeds like Lepodium sativum, Althia officinalis and Occimum sanctum has been evaluated by IP method and optimised method for 24 h. Optimized method gives superlative results over IP method. Plantago seeds moistened with 1ml of 90% alcohol followed by addition of distilled water at room temperature along with every 3 h agitation shows exceptional swelling as compared to other methods and conditions.

Optimization of Digestion Method for Determination of Copper in Shrimp Paste Sample Using Flame Atomic Absorption Spectrometry

Optimization of Digestion Method for Determination of Copper in Shrimp Paste Sample Using Flame Atomic Absorption Spectrometry

A chemometric optimization of method for determination of nitrosamines in gastric juices by GC–MS

A chemometrically optimized isolation procedure combined with gas chromatography-mass spectrometry detection technique has been proposed for quantitative determination of trace levels of nitrosamines in gastric juice samples of patients with the gastrointestinal tract problems. The extraction conditions of each nitrosamine were optimized using regression modelling based on central composite design. The extraction conditions for all nitrosamines were selected to be 10.7min for extraction time, 4.2 for pH and 23 for 2-propanol percentage in extraction solution.The obtained recoveries of nitrosamines ranged from 94.0 (NDMA) to 99.3 (NDPheA) %, and the precision of this method, as indicated by the relative standard deviations was within the range of 0.7 (NDPheA) and 2.6 (NDMA) %. The detection limits obtained from calculations by using GC–MS results based on S/N=3 were found within the range from 0.3 to 1.1pg/mL. Total nitrosamine concentrations were found at the highest concentration up to 2431.12pg/mL in cancer patients, whereas they were found at the lowest concentration down to 12.18pg/mL in gastritis patients. The classification results of the gastric juice samples in different patient groups were very satisfactory, allowing 100% of patients to be correctly grouped. A new mathematical model has been developed allowing for the classification of gastric juices with a 93.1% success rate based on just the ratio of MNPIZ to DNPIZ. The ratio of MNPIZ to DNPIZ might be considered as a biomarker for the classification of gastric juices of patients and might act as an indicator of increased risk for stomach cancer.

Optimization of a fast INAA method for determination of trace concentrations of chlorine in zirconium based alloy and oxide samples

A simple, fast and sensitive instrumental neutron activation analysis (INAA) method has been optimized for the determination of trace concentrations of chlorine in five types of samples namely zirconium oxide, zircaloy 2, zircaloy 4, Zr–Nb alloy and Zr–Sn alloy samples. The samples were neutron irradiated for short duration (1 min) using pneumatic carrier facility of Dhruva research reactor at a neutron flux of 5 × 1013 cm−2 s−1 and measurement of 1,642.7 keV gamma-ray of 38Cl was carried out using a 40 % HPGe detector coupled to 8 k MCA. Concentrations of chlorine were found to be in the range of 9–575 mg kg−1. The 3σ detection limits of chlorine were in the range of 0.1–2.7 mg kg−1 for various samples.

Chemometric-Assisted Optimization of RP-HPLC Method for Determination of Some Bioflavonoids in Brassica oleracea Species and Their Antioxidative Activity

In the present work, the rapid RP-HPLC method with UV (DAD) detection for simultaneous quantification of bioflavonoids: quercetin, apigenin, catechin, epicatechin, kaempferol, and luteolin in Brassica oleracea species samples (cauliflower, broccoli, and Brussels sprouts) was developed with the aid of LC-Simulator (ACD Labs® suite) software. A series of extracts obtained with different extraction method were evaluated for antioxidant activity. The optimal conditions for separation and quantification were established after nine scouting runs entered to LC-Simulator software. The optimized separation was achieved on Hypersil GOLD aQ column with isocratic elution and mobile phase composition A:2 % acetic acid in water and B:acetonitrile in 91:9 (v/v %) ratio. The Rs values were in the range from 2.6 to 8.00, indicating good selectivity of the method. The obtained results generally show good agreement with published data. Low detection limits (0.02–0.055 μg/mL) were obtained with acceptable recoveries (90–109 %). Total time of analysis was less than 11 min; therefore, the proposed method represents significant improvement over existing methods. Extracts from Brassica vegetables, obtained using different extraction procedures, were studied for their radical scavenging effects. Scavenging of DPPH showed different kinetics at the beginning of the assay period and after 15 min from the initialization of reaction. Different kinetics suggested the presence of polymerized and/or less active antioxidants with different scavenging mechanisms for particular polyphenolic compounds.

Optimization of determination method of food preservatives sodium benzoate and potassium sorbate in milk and beverages by high performance liquid chromatogrphy

Optimization of determination method of food preservatives sodium benzoate and potassium sorbate in milk and beverages by high performance liquid chromatogrphy

Multi-response optimization of sequential injection chromatographic method for determination of lisinopril and hydrochlorothiazide

Recently, a more efficient sequential injection chromatograph (SIC) with a high pressure selection valve has been developed at our laboratory. In the current work, the newly developed SIC system was exploited to optimize and validate a new method for the separation and quantification of lisinopril and hydrochlorothiazide in pharmaceutical preparations. A multi-response optimization study was conducted to screen the effect of mobile phase composition on resolution, reagent consumption, retention time, peak symmetry, peak height and baseline. The factorial design approach was adopted and the effect factors were determined. The SIC method has proven to be a competitor to high performance liquid chromatographic methods with respect to sample frequency, reagent consumption and safety for the environment, besides instrumentation benefits with respect to inexpensiveness, simplicity and portability. Short C18 monolithic columns (30 × 4.6 mm) were used to offer a rapid and reagent-saving procedure. Miniaturized fiber optic spectrometric devices were coupled with the SIC system to provide more instrumentation portability. Satisfactory separation, peak symmetry and theoretical plates were achieved. The SIC method was also accurate (the recovery range was 98.8–101.8%), precise (the RSD range was 0.95–2.29) and sensitive (the limits of detection were below 1.5 μg mL−1).

Occurrence of palytoxin-group toxins in seafood and future strategies to complement the present state of the art

Palytoxin (PlTX) and palytoxin-like (PlTX-like) compounds in seafood have been raising scientific concern in the last years. The constant increase in record numbers of the causative dinoflagellates of the genus Ostreopsis together with the large spatial expansion of this genus has led to intensification of research towards optimization of methods for determination of PlTX presence and toxicity. In this context, identification of seafood species which could possibly contain PlTXs constitutes an important issue for public health protection. In the present paper, worldwide occurrence of PlTX-like compounds in seafood is reviewed, while potential future strategies are discussed. PlTX has been reported to be present in several species of fish, crustaceans, molluscs and echinoderms. In one occasion, PlTX has been identified in freshwater puffer fish whereas all other records of PlTXs refer to marine species and have been recorded in latitudes approximately between 43°N and 15°S. PlTX determination in seafood has relied on different methodologies (mainly LC-MS, mouse bioassay and hemolysis neutralization assay) that have evolved over time. Future recommendations include systematic screening of PlTX in those species and areas where PlTX has already been recorded implementing updated methodologies.

Use of constrained mixture design for optimization of method for determination of zinc and manganese in tea leaves employing slurry sampling

A slurry suspension sampling technique has been developed for manganese and zinc determination in tea leaves by using flame atomic absorption spectrometry. The proportions of liquid-phase of the slurries composed by HCl, HNO 3 and Triton X-100 solutions have been optimized applying a constrained mixture design. The optimized conditions were 200 mg of sample ground in a tungsten carbide balls mill (particle size < 100 μm), dilution in a liquid-phase composed by 2.0 mol L −1 nitric, 2.0 mol L −1 hydrochloric acid and 2.5% Triton X-100 solutions (in the proportions of 50%, 12% and 38% respectively), sonication time of 10 min and final slurry volume of 50.0 mL. This method allowed the determination of manganese and zinc by FAAS, with detection limits of 0.46 and 0.66 μg g −1, respectively. The precisions, expressed as relative standard deviation (RSD), are 6.9 and 5.5% ( n = 10), for concentrations of manganese and zinc of 20 and 40 μg g −1, respectively. The accuracy of the method was confirmed by analysis of the certified apple leaves (NIST 1515) and spinach leaves (NIST 1570a). The proposed method was applied for the determination of manganese and zinc in tea leaves used for the preparation of infusions. The obtained concentrations varied between 42 and 118 μg g −1 and 18.6 and 90 μg g −1, respectively, for manganese and zinc. The results were compared with those obtained by an acid digestion procedure and determination of the elements by FAAS. There was no significant difference between the results obtained by the two methods based on a paired t-test (at 95% confidence level).

Photosynthetic carbohydrate metabolism in wheat (Triticum aestivum L.) leaves: optimization of methods for determination of fructose 2, 6-bisphosphate.

The accurate measurement of fructose 2,6-bisphosphate from plants such as wheat is fraught with difficulty. Extraction and assay methods for fructose 2,6-bisphosphate that give near 100% recovery of the metabolite, and a linear response with volume have therefore been developed for extracts prepared from wheat leaves of different ages. Amounts of fructose 2,6-bisphosphate in different regions of leaves generally showed a positive correlation with chlorophyll content. Measurements of sucrose and starch in third leaves harvested at different times of the diurnal cycle demonstrated that sucrose is the major form in which photosynthate is stored in the leaf, but starch can account for up to about 30% of the stored carbohydrate. Virtually all of the carbohydrate accumulated as starch and sucrose during the day was degraded at night. Amounts of fructose 2,6-bisphosphate were generally lower in extracts prepared from leaves harvested in the light than in the dark. Additionally, there was no change in either the amount of fructose 2, 6-bisphosphate or the ratio of sucrose to starch in samples prepared from leaves harvested at different times of the day. These results are broadly consistent with a role for fructose 2,6-bisphosphate in the regulation of sucrose synthesis and the partitioning of carbohydrate between sucrose and starch in wheat leaves.