Journal of Chemical Metrology

Avicennia officinalis L. is a medium-sized evergreen mangrove shrub belonging to the Acanthaceae family. The leaves of this plant are widely used in traditional medicine across Asia. Recently, demand for this herb and its extracts has increased, particularly for herbal product development. This study aimed to optimize the ultrasound-assisted extraction (UAE) of A. officinalis leaves and quantify luteolin-7-O-glucuronide (L7Gn) and luteolin-7-O-rutinoside (L7R) using high-performance liquid chromatography (HPLC). The optimal UAE conditions were a liquid-to-solid ratio of 10:1, extraction with 50% ethanol for 20.4 minutes, as determined by the Box–Behnken design. Under these conditions, the extract contained 124.65 mg of L7Gn and 67.22 mg of L7R per 100 g of dried leaf powder. These optimized parameters were used to validate the quantification method. Bioactive compounds from the A. officinalis leaf extract were identified by ultra-fast liquid chromatography coupled with a diode array detector. The method was then applied to quantify L7Gn and L7R in leaf samples collected from Ngoc Hien District, Ca Mau Province, Vietnam. The ethanol extracts contained L7Gn levels ranging from 2.50 to 2.91 mg/g and L7R levels ranging from 1.58 to 1.73 mg/g. This is the first study to quantify L7Gn and L7R in A. officinalis leaves. The findings provide initial scientific evidence and establish a foundation for further research on this species.

A simple, sensitive, and validated gas chromatography–mass spectrometry (GC–MS) method was developed for the quantitative determination of sulfur in topical formulations. The separation was achieved on a TR-5MS capillary column (30 m × 0.25 mm ID, 0.25 µm film thickness) using helium as the carrier gas at a flow rate of 1 mL/min. The oven temperature was maintained at 190 °C, and the total analysis time was 13 min. Detection was performed in selective ion monitoring (SIM) mode at m/z 64. The injection volume was 1 µL. The method exhibited excellent linearity within the concentration range of 0.75–15.00 µg/mL. The lower limit of detection (LOD) and quantification (LOQ) were found to be 0.25 µg/mL and 0.75 µg/mL, respectively. Mean recovery values ranged from 98% to 102%, with intra- and inter-day precisions (RSD) not exceeding 2%. Method validation was conducted in accordance with the ICH Q2(R1) guidelines. Furthermore, measurement uncertainty was evaluated following the EURACHEM approach. The validated method was successfully applied to the determination of sulfur in commercial topical formulations, demonstrating its suitability for routine quality control analysis. 

This study examined the microelement composition and antioxidant activity of nuts and dried fruits that included soya raisin, golden raisin, malayar raisin, dried apricot, dried prune, walnut, peanut, almond, dried mango, dried melon, apricot with stone, cashew, dried kiwi, dried apple, pumpkin seed, pistachio, hazelnut, and rosehip. Ethanol infusions were assessed using the DPPH and ABTS methods to evaluate their ability to eliminate radicals and determine total phenolic content. Among the tested samples, hazelnuts displayed the lowest antioxidant content alongside high toxicity levels, while cashews exhibited the weakest reactivity. To ascertain the trace element content, the samples underwent processing in microwave ovens, and concentrations of various components were measured using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The method's accuracy was further validated using a certified sample material (NIST SRM 1515, apple leaves). The concentrations observed in the samples varied as follows: Al: 4.7–172.1 mg/kg, B: 3.3–50 mg/kg, Cu: 5.6–52.6 mg/kg, Fe: 14.1–145.4 mg/kg, Mn: 0.3–51.3 mg/kg, Ni: 1.5–8.7 mg/kg, Sr: 1.75–78.5 mg/kg, and Zn: 5.8–63.9 mg/kg, and the findings were compared with existing literature on similar matrices. Overall, the results underscore the nutritional significance of hazelnuts and dried grapes as natural antioxidant sources, raise concerns about potential health risks associated with potentially toxic metal accumulation, and emphasize the necessity for ongoing analyses to ensure consumer safety. The novelty of this study lies in its analysis of both antioxidants and minerals found in nuts and dried fruits from Kazakhstan, which are significant in everyday diets, festive events, and traditional medicine.

Reference materials (RMs) are essential for ensuring metrological traceability in various fields, including environmental monitoring, chemical analysis, and the verification of alcohol breath analyzers. One critical property of RMs is their long-term stability, particularly for gas mixtures such as ethanol in nitrogen, which are stored in pressurized aluminum cylinders. This paper describes the preparation of such gas mixtures according to ISO 6142-1, utilizing differential weighing to minimize the influence of ambient conditions and ensure accurate composition. The effects of adsorption of ethanol on the internal surfaces of aluminum cylinders were experimentally investigated. Results indicate that ethanol can remain adsorbed on the cylinder walls even after evacuation, leading to measurable ethanol concentrations upon subsequent refilling with nitrogen. Repeated fillings demonstrated a decrease in ethanol levels, confirming the saturation and gradual desorption behavior. These findings underscore the necessity to consider adsorption effects in the uncertainty budget and composition calculations for low-concentration ethanol-in-nitrogen RMs.