جستجوی مقالات مرتبط با کلیدواژه "hplc-uv" در نشریات گروه "شیمی"

A novel high-efficiency, reusable nanocatalyst functionalized with DABCO charge was successfully fabricated on magnetic silica. This catalyst was identified by XRD, TGA, VSM, FE-SEM, EDX, and FT-IR analyses. Fe3O4@SiO2@Mel@DABCO as a recoverable catalyst for 2-amino-4H-chromenes synthesis. Among the points that lead to the superiority of this catalyst, we can mention the use of green solvent, products with high yield (84-98%) in a short period, suitable temperature conditions, and simple collection of the reaction medium and its ability. In addition, the effectiveness of the synthesized magnetic sorbent in the microextraction method was examined. Due to the magnetic nature of the sorbents, the magnetic solid phase extraction (MSPE) was selected. Fipronil and promethrin were chosen as purpose model analytes and detected by HPLC-UV device. The results showed the LDRs in the range of 0.5-500 μg L-1 (determination coefficient higher than 0.9969). The LODs of the method were calculated to be between 0.11-0.13 µg L-1. The limits of quantification (LOQs) of the technique were also estimated to be in the range of 0.37-0.42 µg L-1. To verify the correctness of the proposed method, the relative standard deviation (RSDs%) inter-day was 2.9% and inter-day was 4.1%. The enrichment factors for fipronil and prometryn were 53 and 61, respectively. Moreover, the absolute recovery was in the range of 60-69%. The batch to batch RSD was also in the range of 3.9-4.3%. The method was successfully used to extract and determine selected pesticides in samples of tomato, cucumber, wastewater, and pear.

In this research, a simple, rapid, and reliable method was developed for isolating and quantifying the primary preservative compound (sodium benzoate (NaB)) and some water-soluble vitamins such as ascorbic acid (C) and five vitamin B compounds, including thiamine hydrochloride (B1), riboflavin-5-phosphate sodium (B2), nicotinamide (B3), pantothenic acid (B5), pyridoxine hydrochloride, (B6) in multivitamin syrup. An ODS column (temperature 35 °C) and a UV detector were used. The mobile phase was pH 3.0 phosphate buffer-methanol at a flow rate of 1.0 mL/min in a gradient elution approach. The analytes mentioned above were separated in 40 min. Method validation was reached by evaluating the detection limit (LOD) and quantification limit (LOQ), accuracy, and instrument precision. The data obtained in real sample analysis agreed with the declared values. The data obtained for under stress multivitamin syrup sample (forced degradation) confirmed no interference effects in the quantification of analytes.

Necessary diet components are vitamins as if should be existed in the food. The B vitamins and vitamin C (water-soluble vitamins) are substances required for chemical processes and substances that occur within living organisms. In this research, a simple, rapid, and reliable method was developed to isolate and quantify a primary preservative compound (sodium benzoate), some water-soluble vitamins such as ascorbic acid (C) and five vitamin B compounds. An ODS column was used with a UV detector at different wavelengths at 35 °C. The mobile phase was pH 3.0 phosphate buffer-methanol at a flow rate of 1.0 mL min−1 in a gradient elution approach. The mentioned analytes above were separated in 40 min. The linearity, limit of detection (LOD), and limit of quantification (LOQ), accuracy, and instrument precision terms were used in the method validation. The correlation factor near 1 suggests that the developed method has a good linearity range. The results show that recovery percentage was < 99.480% for all compounds. The limit for mean percentage of recovery is 98-102%, and as all the values are within the limit, it can be concluded that the proposed method is accurate. The results showed no HPLC peaks that could disturb the determination of vitamins/preservatives. The data obtained in real sample analysis were consistent with the declared values. The data obtained from subjected multivitamin syrup sample into stress testing (forced degradation) confirmed that there was no interference effects in the quantification of the analytes.

A new and fast sample preparation method was developed to extract Hippuric acid (HA), Trans,trans-muconic acid (tt-MA), Mandelic acid (MA), and m-Methylhippuric acid (m-MHA) in urine samples using Hollow polymer nanospheres (HPSs), Covalent organic frameworks (COFs), and their mixture (HPS:COF) as an adsorbent, combined with high-performance liquid chromatography-ultraviolet spectrophotometry (HPLC-UV). X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to study the features of the adsorbents. The effect of important factors such as temperature and pH of the sample, amount of sorbent, conditioning and washing solvents, type and volume of desorption solvent, sample volume, and the number of extraction cycles were investigated to achieve the optimal conditions with microextraction by packed sorbent (MEPS) procedure. The applicability of the proposed method was then validated in the laboratory. Finally, the target analytes in the urinary samples of gas station workers were examined. The data analysis showed that using an HPS:COF mixture improves the extraction efficiency in optimal conditions compared to the case where the COF adsorbent is used alone (extraction efficiency, 81-87.5%). Also, a good linear dynamic range (0.1-1000 µg/mL for m-MHA), a low detection limit (0.02 µg/mL for tt-MA), and acceptable intra-day and inter-day precision (1.4-3.6 % and 4.5-8.9 %, respectively) were obtained under similar conditions. Overall, HPS: COF-MEPS exhibited excellent extraction efficiency (85.4-93.3%) and has the potential to replace previous methods in the biomonitoring of BTEX biomarkers in urine.

In the present work, switchable hydrophilic solvent-based extraction (SHSE) followed by high performance liquid chromatography with UV detection (HPLC-UV) was used to determine free amino acids in fertilizer samples. During the phase transformation of SHSE, the organic phase appeared to effectively capture the target analytes. In this extraction technique, 200 μL of a water-immiscible solvent (dipropylamine) is used, which can be solubilized in the acidic aqueous phase. Phase separation is then brought about by the addition of sodium hydroxide. The variables affecting this method were optimized to achieve the best extraction efficiency. The optimized conditions included: volume of sample 25 mL, volume of extraction solvent 200 μL, and extraction time 2 min. Under the optimal experimental conditions, good detection limits (0.0006-0.0021 µmol ml-1), linearities (R2 > 0.997), and precision (relative standard deviation less than 5.0%) were obtained. Finally, the developed method was successfully applied to the determination of target analytes in different types of fertilizer samples and acceptable recoveries (> 97.2%) were obtained.

A facilitated, precise, specificmethodology to determine the amount of total selenium in selenium-enriched biomass of Saccharomyces cerevisiae was designed and implementedusing high-performance liquid chromatography technique and UV detection (HPLC-UV). In this research study, a novel chromogenic reagent of 4, 5-Diamino-o-xylene (DAX) was evaluated for off-line pre-column selenium (IV) complexation. The complex of Se (IV) was eluted isocratically on BRISA LC2 C18 (250×0.46 mm, 5 µm, Teknokroma) analytical column. The mobile phase used was a degassed solution of deionized water and acetonitrile solution in a ratio of 50:50 (v/v) at a flow rate of 1.0 mL/min. UV-Vis detector at 340nm was used for complex detection. The method parameters were validated according tothe ICH Q2 (R1) requirements. The linearity was established over the dynamic range of 25-700 µg L-1 (r2=0.9994). The relative standard deviations (RSDs) were 1.1% for within-day determination (n=6) and 1.8% for between-day determination (n=6). The detection limit (LOD) and quantitation limit (LOQ) were found to be 8.0 and 25 μg L-1, respectively.

We successfully synthesized TMU-24 as metal-organic framework (MOF) and employed as an effective sorbent for preconcentration of the letrozole (LTZ) from biological samples. Using high-performance liquid chromatography with UV detector (HPLC-UV) coupling with solid-phase extraction (SPE) a sensitive, fast, and simple method for deteing of LTZ has been developed. The optimal conditions, such as pH, type of eluent solvents, contact time amount of adsorbent, and adsorption capacity were discussed. Under the optimized conditions, relative recoveries (RR) and preconcentration factor (PF) of the LTZ was obtained in the range of 92.4–99.6% and 33 respectively. Under the optimal conditions, LTZ can be determined with a limits of detection (LODs) 0.5 μg L-1 (based on S/N = 3), a linearity in the range of 1–250 μg L-1, and a reasonable linearity of 0.995. Also, the experimental adsorption isotherms models were investigated. The developed method was successfully used to the analysis of LTZ in urine samples.

AgNPs-Tragacanth conjugate gel as an eco friendly and low cost membrane was applied for the effective electromembrane extraction (EME) of Tenofovir disproxil fumarate, an important acidic and high polar (log p=1.25) antiviral drug, followed by HPLC-UV determination. The effect of various parameters on the extraction efficiency including the presence of AgNPs, tragacanth gum concentration, gel thickness, pH values of the donor and acceptor phases, applied voltage, extraction time and agitation rate were investigated and optimized. The best extraction efficiency was obtained with: 2.5% w/v of tragacanth gum, 4.0 mm gel thickness, donor phase pH = 7.0, acceptor phase pH = 8.0, applied voltage: 30 V, extraction time: 15 min and agitation rate: 500 rpm. During method validation under the optimized conditions good linearity dynamic range (LDR) between 10-750 ngmL-1 with coefficient of determination (R2) =0.999 was obtained. Limit of detection (LOD) and Limit of quantitation (LOQ) were estimated to be 5.55 ng mL-1 and 10 ng mL-1, respectively. According to the validation results, the RSD values for intra and inter-day precisions were in the range of 0.53 to 10.04% and the relative error (RE %) ranged between -2.31 to 8.20% Finally the applicability of this method in real samples was confirmed by an acceptable performance in extraction and determination of TDF in human plasma samples.