Repeatability Standard Deviation Research Articles

Inter-laboratory study for extraction testing of medical devices

Biocompatibility evaluation of medical devices often relies on chemical testing according to ISO 10993–18 as a critical component for consideration. However, the precision associated with these non–targeted chemical characterization assessments has not been well established. Therefore, we have conducted a study to characterize intra–laboratory (repeatability) and inter–laboratory (reproducibility) variability associated with chemical testing of extractables from polymeric materials. To accomplish this, this study focused on two polymers, each with nine chemicals that were intentionally compounded into the materials. Eight different laboratories performed extraction testing in two solvents and subsequently characterized the extracts using gas chromatography and liquid chromatography methods. Analysis of the resulting data revealed the central 90 % range for the repeatability and reproducibility relative standard deviations are (0.09, 0.22) and (0.30, 0.85), respectively, for the participating laboratory methods. This finding implies that if the same sample was tested by two different laboratories using the same extraction conditions, there is 95 % confidence for 95 % of systems that the test results could exhibit differences up to 240 %. While the study was not designed to evaluate the relative impact of specific underlying factors that may contribute to variability in quantitation, the data obtained suggest the variability associated with analytical method alone is a substantial contribution to the overall variability. The relatively large reproducibility limits we observed may have significant implications where variability in extraction measurements can impact aspects of biocompatibility risk evaluation, such as exposure dose estimation and chemical equivalence assessments.

Automated vision-based concrete crack measurement system

Maintaining and ensuring the safety of ageing infrastructures is becoming of uttermost importance. This is particularly critical in Europe, where several infrastructures like tunnels and bridges are approaching their end-of-life. Such a condition justifies the need for a prompt recognition of the deterioration status of these structures as well as the identification of strategies for effective inspection and monitoring operations. This paper focuses on cracks, and proposes a vision-based measurement system aimed at precisely and accurately detecting cracks on concrete surfaces and measuring their geometric features. The system mainly leverages RGB-D cameras to make the pixel to real world measurement units conversion possible (by assessing the camera to target relative distance and pose), and exploits an image processing pipeline consisting of the following steps: (a) an artificial intelligence-based semantic segmentation model for identifying cracks on the target structure; (b) a ridge detection algorithm for identifying the centre line of the cracks; (c) a geometric feature extraction algorithm to extract key metrics of the crack, like its width and length. Variance analysis of the crack mean width measurement shows a repeatability standard deviation of 0.01 mm and a reproducibility standard deviation of 0.02 mm, with a Type A expanded uncertainty of 0.004 mm. The system performance is discussed in the paper referring both to lab testing activities, targeted to the assessment of its metrological characteristics, and to a real field application, i.e. concrete inspection in a tunnel. This latter application is of particular interests as it is targeted to demonstrate the robustness of the approach in harsh environments (i.e., strong presence of dust, total absence of natural light) and on surfaces whose roughness generates important light gradients and shadows (e.g., sprayed concrete).

Validation of Analytical Method for Vitamin A in Bioadhesive Ocular Cationic Nanoemulsion Loaded into Thermosensitive Gel Using RP-HPLC

Various test methods have been previously documented for determining vitamin A levels in different dosage forms. This study specifically examines an isocratic reverse phase-high performance liquid chromatography (RP-HPLC) method designed for the direct extraction of vitamin A. The objective is to validate an analytical method for quantifying vitamin A in bioadhesive cationic nanoemulsions incorporated into thermosensitive gels. The method employs isocratic RP-HPLC with a YMC-Triart C18 column (L1), dimensions of 4.6 mm × 250 nm, particle size of S-5 µm, and a UV detector at λ = 265 nm. The mobile phase consists of HPLC-grade methanol, acetonitrile, and n-hexane in a ratio of 46.5:46.5:7. Validation parameters were assessed including selectivity, linearity, accuracy, precision, limit of quantification (LOQ), and limit of detection (LOD). Correlation coefficients were determined with an R2 value of 0.9995 in the concentration range of 264–396 μg/mL (w/v). Recovery percentages ranged from 99.295% to 99.878%. Repeatability and intermediate precision relative standard deviations (RSD) were found to be 0.318% and 0.254%, respectively. The LOD was established at 2.018 μg/mL, and the LOQ was determined to be 6.114 μg/mL. The results affirm cost-effective and well-suited for the accurate measurement of vitamin A levels in bioadhesive thermosensitive gel formulations.

Large scale screening and quantification of micropollutants in fish from the coastal waters of Cochin, India: Analytical method development and health risk assessment

Urban estuarine and coastal water receive several micropollutants through industrial and agricultural influxes. The bioaccumulation of these micropollutants in fish and their entry into the coastal population's food chain raises significant food safety concerns. Hence, a comprehensive analytical method was developed for ultra-trace level quantification of 345 micropollutants in fish. The optimized sample preparation method could extract compounds suitable for both GC–MS/MS and LC-MS/MS analysis simultaneously. The target list of contaminants included 278 agricultural pesticides and also 102 endocrine disruptors covering polyaromatic hydrocarbons, polychlorinated biphenyls, organochlorines, and endocrine-disrupting pesticides. The GC–MS/MS with large volume injection (LVI) technique, and LC-MS/MS operating in MRM mode, achieved an LOQ of <2.00 ng/g for most of the analytes. The extraction strategy involved tri-phase partitioning between water, acidified acetonitrile, and hexane, followed by salting out. Dispersive solid phase cleanup (dSPE) with C18, Z-Sep+, CaCl2, and MgSO4 was able to reduce the matrix influence, and the method achieved satisfactory recovery in the range of 70.0–120.0 % for all the target analytes. The repeatability and reproducibility relative standard deviation values of the measured analytes were <20.0 %, and the Horwitz ratio values were well below 2. The method was used to accurately measure the target micropollutants in fish from the Cochin estuary, the highly urbanized portion of the Vembanad Lake, and an important Ramsar site. At least one or more of the 41 different micropollutants were identified and quantified in about 90.7 % of the 108 samples analyzed. The importance of large-scale screening and trace-level quantification methods in environmental monitoring and risk assessment is underscored by the results. The risk assessment showed a moderate risk of exposure to the nearby coastal population through the food chain.

A new method to analysis synthetic acetic acid to vinegar: Hydrogen isotope ratio at the methyl site of acetic acid in vinegar by GC-IRMS

Acetic acid is the key organic substance used to verify the authenticity of vinegar. A new method for precisely determining acetic acid δDCH3 in vinegar via gas chromatography −pyrolytic-stable isotope ratio mass spectrometry (GC-P-IRMS) was established. The δDCH3 values were obtained via calibration with a series of standards. The optimised method demonstrated a repeatability standard deviation within 3 ‰. The standard deviation of accuracy of the new method compared with that of the SNIF-NMR method was within 2.6 ‰. The synthetic acetic acid δDCH3 values was −136.7 ‰ ± 29.6 ‰, and the δDCH3 value of acetic acid in vinegar was −414.9 ‰ ± 40.5 ‰, with significant isotopic distribution characteristics. This methodology serves as a supplementary method for measuring the δDCH3 value of acetic acid in vinegar. It has advantages over other methods in terms of time, sensitivity and operability. And provides a new idea for solving the problem of analyzing substances in the presence of exchangeable groups.

Type A standard uncertainty evaluation in one measurement through uncertainty propagation from voxel values’ distribution for computed tomography metrology

According to the guide to the expression of uncertainty in measurement, ‘type A evaluation’ generally requires repeated measurements, which are time-consuming for CT scans. To solve this problem, we developed a method for estimating the standard deviation of measurement results in one measurement through uncertainty propagation, which can be regarded as repeatability standard deviation to evaluate the type A standard uncertainty. The method first fits the CT voxel value distribution, uses the ISO50 method to determine the spatial distribution of surface points from the voxel value distribution and edge shape interpolation, and then derives the measurement results by fitting geometric parameters with the least square algorithm. Finally, the standard deviation of the measurement results is evaluated according to the distribution of the surface point position through uncertainty propagation. We performed simulations and experiments using the hole-plate with 28 holes to compare the uncertainty evaluated by our method and the type A standard uncertainty evaluated on the basis of a series of observations obtained under repeatability conditions. Both simulation and experimental results show that these two uncertainties follow the same statistical variation pattern. The Pearson correlation coefficients of the two uncertainties in simulation and experiment are 0.79 and 0.33, respectively, indicating that the uncertainty evaluated by the proposed method can directly replace the type A uncertainty or provide a reference similar to type A uncertainty for the evaluation of the combined uncertainty.

Detection of arsenic and lead ions in water through validation of the electrothermal atomic absorption method

The validation of the electrothermal spectrometry method for Arsenic and lead determination in water samples guarantees the quality of analytical data. The study was carried out at AQLAB. A theoretical and technical investigation was applied to ensure the reliability and accuracy of the analytical method. Parameters such as INEN standards, Eurachem international standards, AQLAB internal documents and environmental standards were used to validate the process. Several readings were performed on different samples to make calibration curves for As and Pb, evaluate the method's linearity, and obtain information on the slope, intercept and determination coefficient. Statistical calculations were used to determine the limit of detection and quantification, repeatability, reproducibility, trueness and uncertainty. The results show that the hypotheses were fulfilled, calibration curves with determination coefficient higher than 0.995, repeatability standard deviation lower than 16%, calculated F &lt; critical F (4.96), calculated t student &lt; theoretical (2.23), trueness was between 100.29-110.18 and 99.64-107.92%, uncertainty was 20% range 0.005 to 0.10 mg/L and 15% range 0.01- 0.20mg/L, limit of detection was 0.001 and 0.005 mg/L and limit of quantification was 0.01 and 0.02mg/L, respectively. Therefore, the validation method was robust and accurate. Keywords: water samples, analytical data, reliable results, Arsenic, Lead, validation

Detection of arsenic and lead ions in water through validation of the electrothermal atomic absorption method

The validation of the electrothermal spectrometry method for Arsenic and lead determination in water samples guarantees the quality of analytical data. The study was carried out at AQLAB. A theoretical and technical investigation was applied to ensure the reliability and accuracy of the analytical method. Parameters such as INEN standards, Eurachem international standards, AQLAB internal documents and environmental standards were used to validate the process. Several readings were performed on different samples to make calibration curves for As and Pb, evaluate the method's linearity, and obtain information on the slope, intercept and determination coefficient. Statistical calculations were used to determine the limit of detection and quantification, repeatability, reproducibility, trueness and uncertainty. The results show that the hypotheses were fulfilled, calibration curves with determination coefficient higher than 0.995, repeatability standard deviation lower than 16%, calculated F &lt; critical F (4.96), calculated t student &lt; theoretical (2.23), trueness was between 100.29-110.18 and 99.64-107.92%, uncertainty was 20% range 0.005 to 0.10 mg/L and 15% range 0.01-0.20mg/L, limit of detection was 0.001 and 0.005 mg/L and limit of quantification was 0.01 and 0.02mg/L, respectively. Therefore, the validation method was robust and accurate. Keywords: water samples, analytical data, reliable results, Arsenic, Lead, validation.

Two-dimensional grating interferometer with nanometer accuracy

A two-dimensional grating interferometer with the nanometer accuracy is proposed, which employs a transmissive two-dimensional diffraction grating and a corner cube prism in its optical configuration. The distinctive features of this optical path configuration are as follows: (i) Fourfold optical subdivision is achieved based on the principle of secondary diffraction, enhancing optical subdivision capability. (ii) The utilization of a corner cube prism configuration enables parallel retroreflection of diffracted light, facilitating ease of optical alignment. Utilizing a two-dimensional transmissive grating with a period of 4 µm (resulting in an optical signal period of 1 µm after fourfold optical subdivision), the two-dimensional grating interferometer achieves measurement resolutions better than 8 nm along the x and y directions. Within a 100 µm range, the grating displacement errors are superior to ±38 and ±36 nm. The repeatability (standard deviation of error) during a reciprocating motion with a 4 µm stroke is superior to 14 nm. The proposed two-dimensional grating interferometer enables nanoscale resolution measurements, showcasing notable linear measurement capabilities and repeatability. It finds potential applications in ultra-accuracy positioning and machining equipment. The utilization of gratings with smaller periods holds the promise of realizing picometer-level measurement potential.

Sustainable Recovery of Anthocyanins and Other Polyphenols from Red Cabbage Byproducts.

The objective of this work was to develop a sustainable process for the extraction of anthocyanins from red cabbage byproducts using, for the first time, apple vinegar in extractant composition. Our results showed that the mixture 50% (v/v) ethanol-water, acidified with apple vinegar, used in the proportion of 25 g of red cabbage by-products per 100 mL of solvent, was the best solvent for the preparation of an anthocyanin extract with good stability for food applications. The chemical characterization of this extract was performed by FTIR, UV-VIS, HPLC-DAD, and ICP-OES. The stability was evaluated by determining the dynamics of the total polyphenol content (TPC) and the total monomeric anthocyanin pigment content (TAC) during storage. On the basis of the statistical method for analysis of variance (ANOVA), the standard deviation between subsamples and the repeatability standard deviation were determined. The detection limit of the stability test of TPC was 3.68 mg GAE/100 g DW and that of TAC was 0.79 mg Cyd-3-Glu/100 g DW. The red cabbage extract has high TPC and TAC, good stability, and significant application potential. The extracted residues, depleted of anthocyanins and polyphenols with potential allelopathic risks, fulfill the requirements for a fertilizing product and could be used for soil treatment.

Limonun evde işlenmesi sırasında bazı insektisitlerin kalıntılarının değerlendirilmesi

The goal of this study was to assess the residues of some insecticides (abamectin, buprofezin, etoxazole) applied on the lemon fruits during its cultivation and to investigate the consequence of household processing such as peeling, jam production, freezing and storage on the residues. A multi-residual analysis method based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure and liquid chromatography coupled with triple quadrupole mass spectrometry was used. Mean recovery (measure of trueness; 70-120%), precision (as repeatability and interim precision relative standard deviation &amp;lt;20%) and limit of quantification (0.01 mg/kg &amp;lt; MRLs) were in accordance with the criteria set in the international guideline. Lemon samples were purchased from Bursa markets in April 2018. The experimental studies and statistical evaluations were conducted at Bursa University Agriculture Faculty (Bursa -Türkiye) between 5 May 2018-30 July 2022. The results revealed that pesticide residues mostly dispersed on the peel, therefore, peeling step decreased the residue level by 90-100% in the pulp of the fruit. Fruit juice and jam production operations decreased the residue level by 87- 100%. Processing factors were less than 1 for fruit juice and jam processing, on the other hand, it was greater than 1 for the separation, grating, freezing and storage of the peels.

A new approach to detecting sugar syrup addition to honey: Stable isotope analysis of hexamethylenetetramine synthesised from honey monosaccharides (fructose and glucose)

One of the most common types of adulteration of honey involves the addition of invert sugar syrups. A new method was developed to measure the stable isotope ratios of carbon and carbon-bound non-exchangeable (CBNE) hydrogen from specific molecular positions in fructose and glucose in honey. This was achieved through periodate oxidation of the sugars to produce formaldehyde, followed by reaction with ammonia to form hexamethylenetetramine (HMT). The preparation was simplified, optimized, and validated by isotopic analysis of replicate syntheses of HMT from fructose, glucose, sugar syrup and a representative authentic honey sample. The optimized method had a repeatability standard deviation from 1.5‰ to 3.0‰ and from 0.1‰ to 0.4‰ for δ2H and δ13C, respectively. This methodology has advantages over alternative isotopic methods, for measuring CBNE hydrogen isotope ratios in sugars, in terms of time, sensitivity and operability and offers a complementary method to differentiate authentic honey from invert sugar syrups.

Magnetic layered double hydroxides for the sensitive dispersive solid phase microextraction of hippuric acid in urine samples prior to HPLC-UV analysis

The core- shell structural layered double hydroxide (Fe3O4-SiO2-EN@Zn-Al-LDH) was successfully synthesized and applied as a solid sorbent in the magnetic dispersive micro solid-phase-extraction (M-DµSPE) method. It was combined with high-performance liquid chromatography for the trace analysis of hippuric acid (HA) from urine samples. The obtained magnetic layered double hydroxides (LDHs) were characterized by XRD, FT-IR, VSM, FE-SEM, and BET techniques. The characterization analysis indicated that Fe3O4- SiO2- EN@ Zn-Al-LDH has a sufficient surface area and good saturation magnetism. The affecting variables on the extraction of HA by the proposed method were optimized. Excellent adsorption capacity (127.8 mg g−1), wide linearity dynamic range (0.015–500 µg mL−1), and satisfactory limits of detection and quantification (0.055 and 0.014 µg mL−1, respectively) could be obtained under optimum conditions. The good repeatability and low relative standard deviation (7.2 %), low carry-over (2.7%), good matrix effect (93.6%), high reusability (up to 19 times), and an acceptable percent recovery value (97.2%) proved the selectivity and applicability of the proposed method for the extraction of the trace levels of HA in real urine samples.

New Method for Quality Assurance of Asphalt Pavements Using a Low-Activity Nuclear Density Gauge

A method was developed for measuring the density of finished asphalt pavement layers using a low-activity nuclear density gauge (LNDG) that is exempt from licensing and other nuclear regulatory burdens in the United States. The gauge using this method, LNDG/TM, requires operating in transmission mode—inserting the gamma-ray source at 0.5 in. (12.5 mm) into the asphalt layer. This method is fast and less destructive than the industry-accepted core-extraction (CE) method—CE followed by laboratory density measurement. This paper presents the measurement principles, method, and properties of this gauge. For evaluating the method, several laboratory and field studies were conducted in North Carolina, USA. For surface course measurements, the repeatability standard deviation of the measurement was 0.3 lb/ft3 (5 kg/m3), and the reproducibility standard deviation was 0.5 lb/ft3 (8 kg/m3). The measurement sensitivity is similar to that of the CE method. The depth of measurement of the gauge is about 2 in. (50 mm). For layers with mean texture depth from 0.5 to 1 mm, the density error is less than 2 lb/ft3 (32 kg/m3). The LNDG/TM requires a density correlation method to provide accurate measurements. Following this method, LNDG/TM density measurements showed a good correlation (correlation coefficient = 0.9) and agreement (root mean square error = 1.3 lb/ft3 [21 kg/m3]) to that using the CE method. These findings indicate that LNDG/TM is a promising alternative to the CE method and has the advantage of testing more locations for acceptance testing.

Clinical application of a new method for determination of the erythrocyte sedimentation rate using the BC-720 automated hematology analyzer.

The erythrocyte sedimentation rate (ESR) is a nonspecific inflammatory indicator and is widely used in clinical diagnosis. Westergren is the gold standard method recommended by the International Committee for Standardization of Hematology (ICSH), but it is time-consuming and inconvenient and has biosafety risks. A new alternate method for ESR (Easy-W ESR) measurement was designed and integrated into the Mindray BC-720 series automated hematology analyzer to meet the clinical needs of hematology laboratories for efficiency, safety, and automation. In this study, the performance of the new ESR method was evaluated based on the ICSH recommendations on modified and alternate ESR methods. Methodological comparisons using the BC-720 analyzer, TEST 1, and the Westergren method were performed to assess repeatability, carryover, sample stability, reference range validation, factors influencing the ESR, and clinical applicability in rheumatology and orthopedics. The correlation between the BC-720 analyzer and the Westergren method was good (Y=2.082 + 0.9869X, r=0.9657, P > 0.0001, n=342), carryover was <1%, the repeatability standard deviation was ≤1 mm/h, and the coefficient of variation (CV) was ≤5%. The reference range meets the manufacturer's claim. For rheumatology patients, the BC-720 analyzer showed a good correlation with the Westergren method (Y=1.021X-1.941, r=0.9467, n=149). For orthopedic patients, the BC-720 analyzer also showed a good correlation with the Westergren method (Y=1.037X + 0.981, r=0.978, n=97). This study verified the clinical and analytical performance of the new ESR method, indicating that the results are very similar to those obtained using the Westergren method.

Portable Smartphone Platform Based on Aggregation-Induced Enhanced Emission Carbon Dots for Ratiometric Quantitative Sensing of Fluoride Ions.

The development of an instrument-free, on-site, real-time, sensitive, and visualized fluoride-ion (F-) content rapid detection strategy is crucial to ensuring the health of the population. Smart microdevices that are portable, directly read, and easy to operate have recently attracted much attention. Herein, a ratiometric fluorescent probe (AA-CDs@[Ru(bpy)3]2+)-based smartphone sensing platform was developed for the detection of F-. The red fluorescent ruthenium bipyridine [Ru(bpy)3]2+ molecule was chosen as the reference signal, and the carbon dots (AA-CDs) with Al3+ aggregation-induced enhanced emission (AIE) were designed as the response signal. The ratiometric probe fluorescence changed continuously from red to cyan in response to different concentrations of F-, and the red-green-blue (RGB) channel values of the fluorescence image were extracted through the smartphone color recognition application (APP). There was a linear relationship between the blue-red (B/R) ratio and the F- concentration, with a limit of detection (LOD) of 1.53 μM, far below the allowable content of F- in drinking water prescribed by the World Health Organization. The F- content was rapidly detected on-site with satisfactory repeatability and relative standard deviation using several water and toothpaste samples as the real sample. The platform features low cost, portability, easy operation, and good stability, selectivity, and repeatability, which provides a powerful tool for the visual quantitative detection of smartphone-based microsensing platforms possibly in the fields of environmental protection, diagnosis, and food safety assessment.

Validation of the CompactDryTM "Nissui" TCR for Rapid Enumeration of Aerobic Bacteria in a Variety of Matrixes: AOAC Performance Tested MethodSM 082201.

CompactDry™ "Nissui" TCR are ready-to-use dry media sheets using a chromogenic medium for the enumeration of mesophilic aerobic bacteria in foods in as little as 24 h. The CompactDry "Nissui" TCR method was validated to achieve AOAC Performance Tested MethodsSM certification. The performance of the CompactDry "Nissui" TCR was compared to that of USDA/FSIS MLG 3.02, FDA BAM Chapter 3, and SMEDP Chapter 6 for 11 matrixes. All 11 matrixes were tested by CompactDry incubation at 35 ± 1°C for 24 ± 2 and 48 ± 3 h. The three dairy matrixes were also evaluated by CompactDry incubation at 32 ± 1°C for 24 ± 2 and 48 ± 3 h and additionally at 72 ± 3 h for nonfat dry milk. After log10 transformation of the data, the standard deviation of repeatability (sr) was similar between CompactDry "Nissui" TCR and the respective reference methods, and method equivalence based on the 90% confidence interval of the difference of means being within (-0.5, 0.5) was demonstrated for all matrixes, incubation temperatures, and incubation times in the method developer and independent laboratory studies. The method was shown to be robust, and data are presented supporting product consistency and 18-month shelf life. The CompactDry "Nissui" TCR method was validated for the determination of mesophilic aerobic bacteria in a variety of matrixes with incubation at 35 ± 1°C for 24 ± 2 and 48 ± 3 h and for dairy matrixes also at 32 ± 1°C for 24 ± 2, 48 ± 3, and 72 ± 3 h. The CompactDry "Nissui" TCR method is equivalent to the USDA/FSIS MLG 3.02, FDA BAM Chapter 3, and SMEDP Chapter 6 reference methods and is suitable for Performance Tested MethodsSM certification for the matrixes tested.

Research and application of direct mercury analyzer (DMA-80) quickly determination of total mercury contents in dietary supplements

The Direct Mercury Analyzer (DMA-80) was studied and investigated to quickly and&amp;nbsp;accurately determine the total mercury content in health supplements. The method shows&amp;nbsp;high specificity, and the calibration curve has a good correlation coefficient with R2 greater&amp;nbsp;than 0.995; the limit of detection (LOD) and limit of quantification (LOQ) were 1.88 &amp;micro;g/kg&amp;nbsp;and 6.26 &amp;micro;g/kg, respectively; The relative repeatability standard deviation (RSRr) was in the&amp;nbsp;range of 2.46 - 7.34% and the recovery (R) was in the range of 85.7 - 100%. The method&amp;nbsp;was applied to evaluate the mercury content in 39 health supplement samples taken in Hanoi&amp;nbsp;city. The initial research results indicated preliminary&amp;nbsp;mercury&amp;nbsp;contamination in 13 health&amp;nbsp;supplement products on the market in the range of 5.41 - 450 &amp;micro;g/kg. &amp;nbsp;

Intelligent use of ethanol for the direct quantitative determination of methanol in alcoholic beverages

A gas chromatography flame ionization detector (GC-FID) method based on the use of ethanol as an internal standard was developed and in-house validated for the direct determination of methanol in ethanol containing products (alcoholic beverages and rectified ethyl alcohol) with ethanol concentrations from 6.5 % to 96.6 % by volume. Validation of the method was performed in terms of linearity, limit of detection (LOD), limit of quantification (LOQ), recovery, repeatability, intermediate precision, trueness, uncertainty and matrix effect. The method showed satisfactory results, considering the parameters of linearity (R2 ≥ 0.999), LOQ and LOD (0.5 and 1.5 mg/L, correspondingly), recovery (95–105 %), standard deviation of repeatability (2.6 %), standard deviation of intermediate precision (3.4 %) and relative expanded uncertainty (with coverage factor k = 2 and confidence level P = 95 %) of method (7.4 %). The developed method has been applied to 23 samples of different types of alcoholic beverages (brandy, gin, rum, calvados, whiskey, bourbon, vermouth, slivovice, tsikoudia, sake, tequila, grappa, mulled wine, strong drink, grain spirit, nalewka, cocktail, krupnik, bitter and sweet tinctures, sweet, herbal and egg liquors). The absence of matrix effect associated with ethanol volume concentration and presence of non-volatile compounds in studied alcoholic beverages was proven.

Comparative Analysis of Resting Heart Rate Measurement at Multiple Instances in a Single Day.

Resting Heart Rate (RHR) is used as an indicator of cardiovascular health and overall fitness. Clinically, RHR is measured from beat-to-beat heart rate data during the day when the body is at rest (RHRrest), typically for ≥ 5 minutes. In this paper, we have compared the RHR measurements done at multiple instances in a single day namely, [Formula: see text], RHR immediately after waking up (RHRmorning) and RHR during sleep (RHRsleep). The significance of measuring RHRsleep and why it can be used as a potential replacement for the conventional methods is analysed through an experimental study in this paper. The results obtained using the proposed method stands out in terms of repeatability. RHR measurements were taken for 3 instances on a single day for 9 subjects on 5 alternate workdays. A comparative analysis was performed by measuring the repeatability coefficient (RC) and Standard Deviation (SD) on the RHR measurements taken during multiple instances for each subject separately. The average RC and SD over the 5 alternate workdays was 5 bpm and SD was 2 bpm for RHRslep. For RHRrest and RHRmorning, the average RC was 12 bpm and 11 bpm and the average SD was 5 bpm and 4 bpm respectively, which is comparatively higher. Hence this method can be potentially adopted instead of the conventional methods as the RHRsleep parameter is more reliable and precise due to its repeatable nature.