Development of a new procedure for the determination of the reactivity of brandies used in wine fortification

The main purpose of this work was to describe and validate a new methodology for the determination of a brandy reactivity index (BRI) towards flavan-3-ol compounds in wines (catechins and condensed tannins) and to correlate this index with the amount and type of aldehydes present in those brandies. This new method consists of two main reactions: a) the ability of aldehydes to react with C8 and/or C6 positions in the phloroglucinol ring of a catechin present in excess (A ring); b) further reaction of the remaining free catechin with p-dimethylaminocinamaldehyde (DMACA) yielding to the formation of a blue compound that can be quantified by Visible spectroscopy at 640 nm. The impact of different experimental conditions such as reagent concentrations and reaction time on BRI were also evaluated. The method was validated through the determination of repeatability (intra-day variability) and reproducibility. The repeatability was considered acceptable with a CV of 11.87 %. The analysis of the reproducibility variance, S2R (11.59), the reproducibility limit R (9.5) and the reproducibility coefficient of variation, CVR (15.25 %) postulates BRI methodology to be reliable and robust.Using the developed methodology, the BRI of fourteen different commercial brandies and some pure standards aldehydes were determined. The aldehydes present in brandies, and the content of total aldehydes were determined by GC-MS and then correlated with the BRI. In general, it was observed a direct correlation between the BRI and the concentration of total aldehydes, in particular acetaldehyde.

Measurement of the Transverse Size of the Eyeball by B-Scanning Using a Linear Probe

Purpose. To evaluate the feasibility of measuring the transverse size of the eyeball by B-scan with a linear probe in patients with horizontal strabismus. Material and Methods. The study included 56 children (56 eyes) aged 2 to 15 years with previously not operated horizontal strabismus. Two independent operators used B-scan method to measure the axial length (for comparison with A-scan data) and the transverse size of the eyeball according to the proposed method. The accuracy of measurements was estimated by calculating the reproducibility limit, and indirectly by the forecast accuracy of the software system STRABO, which used the obtained values of the transverse size of the eyeball for individual dosing operations. Results. The B-scan technique was developed for measuring the transverse size of the eyeball using a contact linear probe. The measurement reproducibility limit was 0.22 mm (95% confidence interval is 0.18–0.25 mm), which does not exceed 1% of the average transverse size of the eyeball (22.03 mm). The results of the operations confirmed the accuracy of the prediction by the software system STRABO, since the correct eye position was obtained within 6 months in all cases, excluding 4 patients in whom the second stage of the surgery was postponed. That gave an indirect confirmation of the measurement accuracy of the transverse size of the eyeball using the proposed technique. Conclusion. The proposed ultrasound B-scan technique with a linear contact probe provides high accuracy and reproducibility of measurements of the transverse size of the eyeball and can be used in pediatric ophthalmological practice for calculating surgical procedures for strabismus using the individual dosing software system STRABO. Key words: transverse size of the eyeball, axial length, ultrasound B-scan, linear probe, horizontal strabismus, dosing.

The Renal Resistive Index in Allografts: Is Sonographic Assessment Sufficiently Reproducible in a Routine Clinical Setting? – Reproducibility of the Renal Resistive Index

Purpose To assess the reproducibility of the renal resistive index (RRI) in a routine clinical setting. Materials and Methods 22 patients with a kidney allograft and 19 physicians participated in our prospective study. Within 2 hours each patient was examined by 5 different physicians using 2 out of 3 different, randomly allocated ultrasound machines. Each investigator determined the hilar and parenchymal RRI of the allograft. The reproducibility and reproducibility limit of the RRI were assessed as well as Cronbach’s alpha and the intraclass correlation coefficient (ICC). The deviation of the RRI from the mean RRI over the 5 measurements was used as an indicator of reproducibility. The impact of the ultrasound machine, examiner’s level of experience, and kidney function impairment (GFR < 45 ml/min) was assessed with the Kruskal-Wallis test. The bivariate linear correlation of the minimal transplant distance from the body surface with the variance of the parenchymal RRI was analyzed. Results A reproducibility of 0.045 with a reproducibility limit of 0.124 was found for the parenchymal RRI. The ICC between RRIs was good with 0.852 for the parenchymal RRI and 0.868 for the hilar RRI. The type of ultrasound machine used was found to have a significant impact on the deviation of the parenchymal RRI (Kruskal-Wallis-Test, p = 0.003). Variance in serial parenchymal RRI measurements correlated significantly with the depth of the kidney transplant (p = 0.001). Conclusion While the RRI is generally sufficiently reproducible, the type of ultrasound machine used and the depth of the kidney transplant within the recipient’s body have a significant impact on reproducibility. Key Points: Citation Format

Precision of laboratory methods based on protein solubility in quality control of heat treated feedstuffs

Some of feedstuffs used as raw materials in feed industry contain anti-nutritional factors that negatively influence their quality. One of them is soybean, which is, prior to oil extraction, referred to as full-fat soybean (FFSB). Anti-nutritional factors in raw FFSB can be destroyed by moderate heating, but both over- and under heat processing limits the availability of soybean amino acids. Among laboratory procedures that are available for assessing the degree of FFSB heat treatment, two methods, i.e. Protein dispersibility index (PDI) and protein solubility in potassium hydroxide (PSKOH), are based on protein solubility, which was claimed to be the most reliable indicator of the degree of FFSB heat treatment. This paper presents the results of an inter-laboratory study conducted to establish precision of the PDI and PSKOH methods by determining their reproducibility limits. Five samples of FFSB were heat-treated at temperatures between 110 and 164 ?C and analyzed by six laboratories for PDI and PSKOH. Established reproducibility limit for PDI method of 8.87 index units found in this study appeared to be too wide, indicating a low precision of this method. PSKOH method produced very good reproducibility limit of 8.56% and could be recommended as a preferred method for FFSB quality control in feed laboratories.

Comparisons of temperature, pressure and humidity measurements by balloon-borne radiosondes and frost point hygrometers during MOHAVE-2009

We compare coincident, in situ, balloon-borne measurements of temperature (T) and pressure (P) by two radiosondes (Vaisala RS92, Intermet iMet-1-RSB) and similar measurements of relative humidity (RH) by RS92 sondes and frost point hygrometers. Data from a total of 28 balloon flights with at least one pair of radiosondes are analyzed in 1-km altitude bins to quantify measurement differences between the sonde sensors and how they vary with altitude. Each comparison (T, P, RH) exposes several profiles of anomalously large measurement differences. Measurement difference statistics, calculated with and without the anomalous profiles, are compared to uncertainties quoted by the radiosonde manufacturers. Excluding seven anomalous profiles, T differences between 19 pairs of RS92 and iMet sondes exceed their measurement uncertainty limits (2 σ) 31% of the time and reveal a statistically significant, altitude-independent bias of 0.5 ± 0.2 °C. Similarly, RS92-iMet P differences in 22 non-anomalous profiles exceed their uncertainty limits 23% of the time, with a disproportionate 83% of the excessive P differences at altitudes >16 km. The RS92-iMet pressure differences increase smoothly from −0.6 hPa near the surface to 0.8 hPa above 25 km. Temperature and P differences between all 14 pairs of RS92 sondes exceed manufacturer-quoted, reproducibility limits (σ) 28% and 11% of the time, respectively. About 95% of the excessive T differences are eliminated when 5 anomalous RS92-RS92 profiles are excluded. Only 5% of RH measurement differences between 14 pairs of RS92 sondes exceed the manufacturer's measurement reproducibility limit (σ). RH measurements by RS92 sondes are also compared to RH values calculated from frost point hygrometer measurements and coincident T measurements by the radiosondes. The influences of RS92-iMet Tand P differences on RH values and water vapor mixing ratios calculated from frost point hygrometer measurements are examined.

Method validation by collaborative trial for the quantification of binary mixtures containing polyamide and a novel polypropylene/polyamide bicomponent fibre

A method for the quantification of a novel polypropylene/polyamide bicomponent fibre in binary mixtures with polyamide was subjected to validation by collaborative trial. Considering the probable acceptance of the novel fibre in Europe, this method would allow market surveillance and antifraud controls needed for consumer protection. The aim of the study was to extend the scope of application of method 11 of Directive 96/73/EC. The method foresaw selective dissolution of the polyamide component using 75% m/m sulfuric acid at room temperature for 1 h. In order to ensure accurate quantification of the blends, two additional rinsings of the residue with the reagent used for the dissolution had to be included in the washing procedure of method 11. Following ISO 5725, a balanced uniform level test was performed, with the participation of seventeen European laboratories, on loop twisted carpet samples of three levels of concentration. The trueness was evaluated considering, as reference, data values obtained from manual separation. The bias varied from 0.06 to 0.49%. Repeatability and reproducibility limits were in the range 0.70–1.04% and 0.97–1.87%, respectively. In agreement with the members of the European Network of National Experts on Textile Labelling, the optimized method was judged fit-for-purpose and the reproducibility limit was established at 2%. Based on this study, the novel fibre can be inserted in the scope of application of method 11 as the insoluble component ( d factor 1.005) and polyamide as the soluble one, provided that modifications are adopted.

Evaluation of Analytical Methods Used for Regulation

Regulatory analysis requires methods for analysis for 3purposes: surveillance, to detect problems; monitoring, to follow trends; and compliance, to enforce specifications (standards, action levels, tolerances). Each purpose requires a different weight to be assigned to the relative importance of the scientific characteristics of methods of analysis: systematic error, repeatability, reproducibility, limit of determination, and specificity. Evaluation consists of balancing the level of scientific requirements against the practical considerations of cost, time, and level of (raining required. In trace analysis, FDA utilizes recovery limits of 80-110% at ≥0.1 ppm and 60-100% below. The criterion for acceptable reproducibility (total of between- and within-laboratories) of methods of analysis can be represented by a relationship between coefficient of variation and concentration. The results of collaborative studies show that 10% outliers must be tolerated, but above 20% is excessive. Other new, important criteria for evaluation of methods at trace levels are % false positives, false negatives, and the magnitude of the blank.