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Acta Alimentaria
Authors: E. Schall, Zs. Bugyi, L. Hajas, K. Török, and S. Tömösközi

Quantitation of gluten in gluten-free products is a great challenge as it is hindered by several factors including the lack of certified reference materials. To resolve this problem, our research group, in cooperation with other international experts, started a series of experiments with the goal of the production of a suitable gluten reference material. As a part of this research, several different wheat cultivars and their isolated gluten proteins were characterized by different methods, including enzyme-linked immunosorbent assay (ELISA). However, we need to know the performance of the ELISA methods used for this special area of research. During the present work we investigated the accuracy and precision of two different ELISA methods for our own laboratory conditions and special sample matrices (wheat flours and gliadin isolate). We have found that the tested performance characteristics of the methods seem to be appropriate on a case-by-case basis, but the long-term measurement uncertainty is higher, which makes it difficult to evaluate the results obtained with the ELISA method for these types of samples.

Open access

Abstract  

The calorimetry exchange (CALEX) program is administered by New Brunswick Laboratory (NBL). The main objective of the program is to provide an independent verification of the internal quality control practices in nuclear material safeguards facilities making plutonium accountability measurements by non-destructive calorimetry/gamma spectrometry techniques. Facilities measure the calorimetric power, and plutonium and 241Am isotope abundances of CALEX program standards using routine accountability procedures. The measurement results as well as two other quantities (effective specific power and plutonium mass) calculated from these results are evaluated for accuracy (or bias) and precision. In this paper, a limited number of measurement results of a CALEX program standard (identified as Calex I) are evaluated with specific goals to identify a suitable method for uncertainty estimation and to identify the major contributors to the uncertainties. In order to achieve the goals, the Calex I measurement results were evaluated using two different methods: the first method confined to uncertainty estimation from random variations of the measurement results alone, and the second method providing a more comprehensive evaluation of uncertainties from both the measurements and the characterized values of the measured standard according to the Guide to the Expression of Uncertainty in Measurement (GUM). The results of this study, and a subsequent study extended to a larger number of results in the CALEX program database, are expected to provide relevant input for developing the International Target Values for plutonium measurements by the calorimetry/gamma spectrometry method.

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Abstract  

Two separation techniques for strontium determination using AnaLig® Sr01 molecular recognition technology and extraction chromatography Sr®  resin were tested. The methods performance was investigated by analysis of NPL (High Alpha–Beta 2003) intercomparison sample. The results obtained for both procedures were compared in terms of activities and recoveries. Data analysis proved a good agreement with the reference values. The AnaLig® Sr01 separation method for 90Sr determination was successfully validated with the same performance as the Sr® resin method.

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Abstract  

Two separation techniques for plutonium determination using AnaLig® Pu02 molecular recognition technology product (MRT) and extraction chromatography TRU® resin were tested. The methods performance was investigated by analysis of National Physical Laboratory (NPL-Alpha-Beta High, ABH 2003, 2005) intercomparison test samples. The results obtained for both procedures were compared in terms of activities and recoveries. Data analysis showed good agreement with the reference values. The AnaLig® Pu02 separation method for 239,240Pu, 238Pu determination was successfully validated with the same performance as the TRU® resin method.

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Abstract  

In this paper rapid separation methods for strontium determination using molecular recognition technology products 3M Empore™ Sr disc, AnaLig® Sr-01 and extraction chromatography Sr® Resin were presented and statistical tested. The methods performance was investigated by analysis of NPL (High Alpha–Beta 2003) and (High Alpha–Beta 2005) intercomparison samples. The presented results were evaluated as correct for all experimental data. We used linear regression (with regression diagnostics), t test and the mean of variable using 90Sr with 3M Empore™ Sr disc, AnaLig® Sr-01 and Sr® Resin.

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The Savannah River Site Environmental Bioassay Lab participated in the 2008 NRIP Emergency Response program administered by the National Institute for Standards and Technology (NIST) in May, 2008. A new rapid column separation method was used for analysis of actinides and 90Sr in the NRIP 2008 emergency water and urine samples. Significant method improvements were applied to reduce analytical times. As a result, much faster analysis times were achieved, less than 3 hours for determination of 90Sr and 3–4 hours for actinides. This represents a 25%–33% improvement in analysis times from NRIP 2007 and a ∼100% improvement compared to NRIP 2006 report times. Column flow rates were increased by a factor of two, with no significant adverse impact on the method performance. Larger sample aliquots, shorter count times, faster cerium fluoride microprecipitation and streamlined calcium phosphate precipitation were also employed. Based on initial feedback from NIST, the SRS Environmental Bioassay Lab had the most rapid analysis times for actinides and 90Sr analyses for NRIP 2008 emergency urine samples. High levels of potential matrix interferences may be present in emergency samples and rugged methods are essential. Extremely high levels of 210Po were found to have an adverse effect on the uranium results for the NRIP-08 urine samples, while uranium results for NRIP-08 water samples were not affected. This problem, which was not observed for NRIP-06 or NRIP-07 urine samples, was resolved by using an enhanced 210Po removal step, which will be described.

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The Lawrence Livermore National Laboratory has developed an extensive quality assurance program to provide high quality data and assessments in support of the Marshall Islands Dose Assessment and Radioecology Program. Our quality assurance objectives begin with the premise of providing integrated and cost-effective program support (to meet wide-ranging programmatic needs, scientific peer review, and build public confidence) and continue through from design and implementation of large-scale field programs, sampling and sample preparation, radiometric and chemical analyses, documentation of quality assurance/quality control practices, exposure assessments, and dose/risk assessments until publication. The basic structure of our radioassay quality assurance/quality control program can be divided into four essential elements: (1) sample and data integrity control, (2) instrument validation and calibration, (3) method performance testing, validation, development and documentation, and (4) periodic peer review and on-site assessments. While our quality assurance objectives are tailored towards a single research program and the evaluation of major exposure pathways/critical radionuclides pertinent to the Marshall Islands, we have attempted to develop quality assurance practices that are consistent with proposed criteria designed for laboratory accreditation.

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A recently introduced microtiter-plate multienzyme-inhibition assay using rabbit liver esterase (RLE), Bacillus subtilis (BS2) esterase, and cutinase from Fusarium solani pizi has been successfully transferred to high-performance thin-layer chromatography. Paraoxon, malaoxon, and carbofuran as esterase inhibitors with high, medium, and low inhibitory activity, respectively, were used to optimize method performance with regard to enzyme concentration, incubation time, and time of immersion in α-naphthyl acetate-fast blue salt B substrate. For paraoxon as strongest inhibitor, limits of detection (LOD) of 1.3, 1.2, and 540 pg per band were determined using RLE, BS2, and cutinase, respectively. Respective LODs were 7.9, 7.4, and 760 ng per band for malaoxon, and 33, 54, and 1420 ng per band for carbofuran. With regard to the LODs of strong, medium, and weak inhibitors, the detectability range is favorably reduced for the low-sensitivity cutinase (0.54–1420 ng per band) whereas it was approximately 3 × 10 4 and 5 × 10 4 for RLE and BS2, respectively.

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Abstract  

The laboratory for instrumental neutron activation analysis at the Reactor Institute Delft, Delft University of Technology uses a network of 3 gamma-ray spectrometers with well-type detectors and 2 gamma-ray spectrometers with coaxial detectors, all equipped with modern sample changers, as well as 2 spectrometers with coaxial detectors at the two fast rabbit systems. A wide variety of samples is processed through the system, all at specific optimized (and thus different) analytical protocols, and using different combination of the spectrometer systems. The gamma-ray spectra are analyzed by several qualified operators. The laboratory therefore needs to anticipate on the occurrence of random and systematic inconsistencies in the results (such as bias, non-linearity or wrong assignments due to spectral interferences) resulting from differences in operator performance, selection of analytical protocol and experimental conditions. This has been accomplished by taking advantage of the systematic processing of internal quality control samples such as certified reference materials and blanks in each test run. The data from these internal quality control analyses have been stored in a databank since 1991, and are now used to assess the various method performance indicators as indicators for the method’s robustness.

Open access

Abstract

Chloroquine phosphate (CQ) the antimalarial drug and suggested to treat the pandemic disease coronavirus (COVID-19) is often adulterated with some of the non-steroidal anti-inflammatory drugs (NSAIDs) such as paracetamol, aspirin (ASP), or both. The purpose of this study is to detect such counterfeited drugs, using a reversed phase high pressure liquid chromatography (RP-HPLC) method with fluorescence detection. Analysis was divided into three phases. In the first phase, a Plackett-Burman design (PBD) was used to screen five independent factors, namely, buffer pH, buffer concentration (mM), acetonitrile content (%), flow rate (mL/min) and triethylamine (TEA) content in the buffer preparation (%). The selected dependent variables were (resolution, symmetry of peaks and run time). The objective of the second phase was to optimize the method performance using Box-Behnken design (BBD) and desirability function for multiple response optimization to obtain the best chromatographic performance with the shortest run time. Optimal chromatographic separation was achieved on a YMC-pack pro C18 ODS-A column (15 cm × 4.6 mm, 5 µm) at room temperature The optimum mobile phase consisted of acetonitrile and 5 mM sodium dihydrogen phosphate buffer containing 0.5% triethyamine (30:70, v/v) with the pH adjusted to 3.5 using an orthophosphoric acid solution. The flow rate was maintained at 1 mL/min, and the detection was performed with a fluorescence detector fixed at 380 nm (λemission) after excitation at 335 nm (λexcitation). The third phase was method validation according to ICH guidelines, providing to be specific, precise, accurate, and robust. The method is linear over a range of 0.4–8 µg/mL for chloroquine and ASP, while for paracetamol it is linear over 16–48 µg/mL. The developed RP-HPLC method was used for quantitation of the three drugs in chloroquine dosage form samples. The method shows a great tendency in the classification between the genuine chloroquine and the adulterated ones in pharmaceutical preparations and breast milk.

Open access