Journal of Chemical Metrology

Harpagoside, an iridoid glycoside, is the primary active compound found in Harpagophytum procumbens DC. ex Meisn. The main goal of this work was to develop a high-performance liquid chromatographic (HPLC) method for measuring the amount of harpagoside in different cream samples that is rapid, straightforward, and accurate. Prior to chromatographic separation, liquid-liquid extraction was used for the preparation of samples, which is now the predominant extraction technique due to its simplicity, speed, and efficiency. Reversed phase C18 (5 µm × 4.6 mm × 150 mm) analytical column, methanol and water (60:40 v/v) at a flow rate of 1.1 mL/min, and a UV detector that detected at 272±1 nm were used to achieve the chromatographic separation. The linear behaviour of the proposed approach was examined in the 0.1-30 ng/mL range (r2=0.9998). The proposed method is in alignment with the criteria that is established by International Conference on Hormonisation (ICH) about the accuracy, precision, repeatability, specificity, robustness and detection and quantification. Limit of Detection and Limit of Quantification are determined to be 0.03 and 0.1 ng/mL whereas relative standard deviation was determined to be less than 3.42% for daily and hourly measurements. The suggested analytical process is a productive way to measure and routinely analyse harpagoside in creams containing Devil’s claw.

Turbidity is a key indicator of water quality influencing the proliferation of protozoa. Accurate turbidity measurements are essential for optimal water resource management and river basin planning particularly in contexts where water quality is a primary concern. Turbidity of unknown samples is usually measured by turbidity meters or spectrophotometers under one point calibration at 860 nm in the UV region. This creates a measurement limitation since the turbidity of an unknown sample should be the same or quite near turbidity to the CRM. To overcome this limitation, this work describes a new multi-point calibration method for a high-performance Lambda Spectrophotometer equipped with Gallium-Indium-Arsenic (GaInAs) detector. The calibration was carried out using three turbidity standards of 100, 500 and 1000 Nephelometric Turbidity Unit NTU which were measured in the NIR region at 1070, 1372 and 1569 nm respectively. The absorbance of each standard was measured 10 times and the CRM turbidly values were plotted against the measured absorbance values. A very good linear relationship was obtained with R2 of 1 and the linear calibration function can be used to obtain the turbidity of an unknown sample measured at each of the three used wavelengths. The type A and type B calibration uncertainty sources were quantified according to ISO GUM and the calibration results were found to be 100.14± 0.47, 498.03±1.60 and 997.81±3.54 NTU. The method has been applied for measuring turbidity of a CRM sample with a small error of approximately 1%. The developed calibration method will be useful for analytical laboratories serving the water quality in the environmental and industrial sectors.

Standardized analytical methods for determining elemental concentrations require thorough validation and estimation of measurement uncertainty. Inductively coupled plasma optical emission spectrometry (ICP-OES) is a widely used technique for multielement analysis with the ASTM E2941-14 standard specifying the analytical conditions for its application. This study aims to validate the ICP-OES method and estimate the expanded uncertainty for multielement determination in accordance with ASTM E2941-14. Method validation and uncertainty estimation were conducted following Eurachem (2014) and Eurachem-CITAC (2012) guidelines, respectively. The method demonstrated acceptable linearity, with coefficients of determination (R2) ranging from 0.9972 to 1.0000 and correlation coefficients (R) from 0.9982 to 1.0000, exceeding the acceptance criterion (R2/R ≥ 0.995). Accuracy under repeatability conditions showed coefficients of variation between 1.0% and 8.0%, indicating good consistency. Trueness evaluation revealed no significant bias, with recovery rates within the acceptable range of 100% ± 10%. Combined uncertainty values ranged from 0.0425 (silver; Ag) to 0.5156 (scandium; Sc), corresponding to relative uncertainties of 1.25% to 8.16%, respectively. Expanded uncertainties ranged from 0.0850 (Ag) to 1.0312 (Sc). The dominant sources of relative uncertainty were associated with calibration curve-based concentration measurements and volumetric equipment.

This study optimized the extraction of sesamin and 4-hydroxy-sesamin from Cinnamomum camphora residue, yielding 0.3804 % under conditions of 86 ℃, 43 min, and a 1:8.39 solid-liquid ratio. The purified compounds showed 67.86 % and 78.87 % recovery rates via recrystallization. In LPS-induced BV-2 microglia, 4-hydroxy-sesamol (10-40 μmol/L) activated autophagy, reduced iNOS, COX-2, IL-6, IL-1β, TNF-α mRNA expression, and demonstrated neuroprotection without cytotoxicity, suggesting its potential in mitigating neuroinflammation.