mohammadreza vardast

 1,4-Dioxane, a cyclic ether commonly employed in chemical and syntheses processes as a solvent, is now a probable human carcinogen. It is frequently found as a byproduct of detergents and personal care products, so reliable analytical methods to locate and quantify it in cosmetics are important for compliance, regulatory, and public health reasons. 

 We developed an optimized headspace solid-phase microextraction (HS-SPME) method that has the modified carbon fiber as the extraction phase when coupled with GC-FID. The analytical method also allows us to take the best of liquid-liquid extraction and HS-SPME together for better sensitivity in cosmetic matrices.

The method provided adequate sensitivity, detection limit (LOD) of 0.4 μg/kg and quantitation limit (LOQ) of 1.2 μg/kg. The linear dynamic range was 1.5-300 μg/kg, R² > 0.999, precision of 5.8% as RSD at 25 μg/kg, n=6. The carbon fiber modified with aniline/pyrrole/graphene oxide extraction phase had longer extraction times, but was more efficient than conventional fibers due to its π-π modified interactions as well as more areas of contact and surface hydrophobicity.

This method for the headspace solid-phase microextration-gas chromatography-flame ionization detection (HS-SPME-GC-FID) provides a sensitive, reliable, and solvent free method for monitoring, locating, and quantifying 1,4-dioxane in cosmetics to comply with regulatory standards of monitoring carcinogens. The modified carbon fiber exhibits exceptional performance for trace-level extraction of this challenging analyte.

 Given the clinical importance and frequent use of oxytocin in serum and pharmaceutical products, along with the significant impact of improper dosage on both the therapeutic efficacy and adverse effects, this study aimed to develop and validate a dispersive liquid-liquid microextraction (DLLME) method for the rapid and precise measurement of oxytocin concentrations in these matrices.

In this study, a DLLME method was optimized using carbon tetrachloride as the extraction solvent and acetonitrile as the dispersing solvent. Various parameters, including temperature and stirring speed, were systematically investigated and optimized. Analyses were conducted using gas chromatography with flame ionization detection (GC-FID). The materials utilized included oxytocin, ethanol, methanol, acetone, dichloromethane, carbon tetrachloride, acetonitrile, and calcitonin (as the internal standard).

Analysis of oxytocin concentrations in serum and commercial vials (5 and 10 IU/mL doses) from two domestic manufacturers (Company A and B) revealed that Company A’s products more closely matched their labeled concentrations compared to those of Company B. Method validation using a German reference standard (Rotexmedica) demonstrated comparable results for domestic samples, with no statistically significant differences observed. The analytical method showed excellent performance characteristics, with a linear detection range of 0.02–60 IU/mL, a calibration equation of A = 190731C − 21483, and a correlation coefficient (R²) of 0.999.

The developed DLLME method proved to be a simple, cost-effective, and reliable technique for quality control of oxytocin pharmaceutical preparations and the measurement of serum oxytocin levels. The findings revealed significant variations in oxytocin concentrations between different commercial products available in the Iranian market and demonstrated the method’s capability for accurate quantification in biological samples.

The study is a bioequivalence study aimed at assessing the equality of pharmaceutical characteristics between two different products. This research investigates the physicochemical properties and in vitro bioequivalence of various formulations of 200 mg ibuprofen tablets available in the Iranian market and the reference brand after entering the market.

Three formulations of ibuprofen tablets, including one foreign brand as reference and two domestic brands were selected. They were evaluated for the amount of active ingredient (assay), content uniformity, dissolution test according to USP, and the calculation of the difference factor (f1) and similarity factor (f2).

The assay test results for companies G1, G2, and the reference were 106.85%, 100.44%, and 104.8% of the claimed drug amount on the label, respectively. The acceptance value (AV) in the content uniformity test was 10.22, 25.8, and 10.57 for companies G1, G2, and the reference, respectively. In the dissolution test, the average percentage dissolution at the end of 60 minutes was 88.2%, 91.96%, and 92.74% for G1, G2, and the reference, respectively. The difference and similarity factors for G1 were 16.63 and 38.28, and for G2 were 6.06 and 82.51, respectively.

Based on the assay test, all three companies fall within the acceptable range of 90% to 110% of the label, confirming their compliance. In the content uniformity test, which requires an AV below 15, only brands G1 and the reference were approved. All brands were able to release more than 80% of the drug in the tolerance test. Additionally, concerning factors f1 and f2, which should respectively be below 15 and 50, only company G2 was confirmed. According to the results of the in vitro bioequivalence test, none of the generic brands examined have the ability for complete substitution with the reference brand. For company G1, the observed difference in dissolution may be related to differences in the type of coating between the test and reference products; in this case, an in vivo test is also necessary to demonstrate bioequivalence between these two products.

Polyethylene glycol (PEG) solution is used as a laxative for the treatment of constipation in children. Due to the preparation of this solution as a compounding ingredient and solution instability as well as unavailability of the exact expiration date of compounding ingredients, it is necessary and important to investigate the stability of PEG solution.

In order to assess the stability of PEG solution, the prepared solutions were stored in various environments (ambient light and temperature, oven, refrigerator and exposed to constant light) for twelve months. Then, they were evaluated for changes in the physical appearance and odor, pH, electrical conductivity, viscosity, refractive index, and microbial contamination over twelve months.

No change in color, turbidity and odor as well as no microbial growth was observed among any of the samples during the study period, which indicates no polymer precipitation and no microbial contamination. Moreover, there was almost no change in FTIR spectra of all samples over the study period. Samples stored in the refrigerator underwent significant changes in pH, refractive index and viscosity after three months, while samples stored in the oven and exposed to light underwent significant changes from the first month.

Considering the destructive effects of light and temperature on PEG solution stability, which can accelerate the aging process, release organic acids and reduce the pH of the solution, the prepared PEG solutions are recommended to be packaged in dark glass containers (due to incompatibility with many plastic containers), stored at a temperature below 25 ° C (preferably in the refrigerator) and finally used up to one month after product preparation.

Amiodarone is an anti-arthritis drug (III) used to treat various types of arrhythmias. Determining the concentration of this drug in the blood of patients is important for the administration of this drug and its interaction with other drugs (due to its high interaction with other drugs). It is necessary to use precision instruments such as HPLC with expensive detectors, but the analysis is often time-consuming and the methods of extraction have a high cost. Therefore, the liquid-liquid extraction method for rapid and accurate measurement of this medication was used in serum.

The liquid-liquid extraction method was used with a variety of solvent extraction and different types of solvent. After selecting suitable solvents and optimizing various experimental parameters, this method was used to extract and measure the concentration of amiodarone in Blood serum.

The results showed that carbon tetrachloride is suitable as a solvent extraction and acetonitrile is suitable as a solvent, and their optimal volume is 75 and 200 μl, respectively, and the optimal volume of the serum is 100 μl and the appropriate pH is in the two extraction steps 1 and 6. Mean calibration curve of Amiodarone is linear in the range of 0.05-0.0 μg / ml and has a relative standard deviation of 3.79%.

The results indicate that this method is suitable for measuring amiodarone in blood serum and reduces the time and cost of the analysis to a satisfactory level and has a good repeatability. With this method, it is easy to measure the effect of serum tissue in measuring amiodarone.

In this study, a magnetic molecular imprinted polymer was used to measure the diltiazem drug. Based on the structure and pharmaceutical agent group, methacrylic acid was selected as a monomer for Diltiazem. Ethylene glycol de-methacrylate and azobisisobutyronitrile were used as cross-linkers and polymerisation initiators, respectively. Also, chloroform was used as a porogenic solvent. In order to investigate the polymer absorption capacity, a high-performance liquid chromatography system was used which had an absorption capacity of 9.59 mg / g. This allows the measurement and analysis of this drug in biological fluids and separates them from various wastewater.

Methacrylic acid (MAA), ethylene glycol de-methacrylic acid (EGDMA), and azobisisobutyronitrile (AIBN) were obtained from Sigma Aldrich while Diltiazem was obtained from Sobhan-Dar Company. Serum samples were prepared from the medical diagnostic laboratory in Urmia. High-performance liquid chromatography with UV detector was used to determine the concentration of drug in existing samples by experimental method.

The results indicate that this drug is well absorbed by the synthetic polymer, and shows the results of repeated etiology and re-use of this polymer for the drug. It is possible to use this polymer for 5-6 times and it has a capacity of 9.50 mg / g of drug per gram of polymer.

Polymer molecular membrane can act as a good absorbent for absorbing and measuring this drug with respect to the structure of the drug. Therefore, methacrylic acid has been used as polymerization monomer and has shown good results for drug absorption.Keywords: Determination, Polymer Molecular Imprinted, Diltiazem