Generic sample preparation combined with high-resolution liquid chromatography- time-of-flight mass spectrometry for unification of urine screening in doping-control laboratories

A unification of doping-control screening procedures of prohibited small molecule substances—including stimulants, narcotics, steroids, ß2-agonists and diuretics—is highly urgent in order to free resources for new classes such as banned proteins. Conceptually this may be achieved by the use of a combination of one gas chromatography–time-of-flight mass spectrometry method and one liquid chromatography–time-of-flight mass spectrometry method. In this work a quantitative screening method using high-resolution liquid chromatography in combination with accurate-mass time-of-flight mass spectrometry was developed and validated for determination of glucocorticosteroids, ß2-agonists, thiazide diuretics, and narcotics and stimulants in urine. To enable the simultaneous isolation of all the compounds of interest and the necessary purification of the resulting extracts, a generic extraction and hydrolysis procedure was combined with a solid-phase extraction modified for these groups of compounds. All 56 compounds are determined using positive electrospray ionisation with the exception of the thiazide diuretics for which the best sensitivity was obtained by using negative electrospray ionisation. The results show that, with the exception of clenhexyl, procaterol, and reproterol, all compounds can be detected below the respective minimum required performance level and the results for linearity, repeatability, within-lab reproducibility, and accuracy show that the method can be used for quantitative screening. If qualitative screening is sufficient the instrumental analysis may be limited to positive ionisation, because all analytes including the thiazides can be detected at the respective minimum required levels in the positive mode. The results show that the application of accurate-mass time-of-flight mass spectrometry in combination with generic extraction and purification procedures is suitable for unification and expansion of the window of screening methods of doping laboratories. Moreover, the full-scan accurate-mass data sets obtained still allow retrospective examination for emerging doping agents, without re-analyzing the samples

Inventarisatie en selectie van analysemethoden voor meststoffen

In dit rapport wordt een overzicht gegeven van parameters die in meststoffen dienen te worden bepaald en de beschikbare en beschreven analysemethoden. Op basis van een aantal selectiecriteria heeft RIKILT aan LNV een voorstel gedaan voor analysemethoden voor monsters die zijn genomen in het kader van controle en handhaving van de regelgeving voor het verhandelen van meststoffen. Dit alles in het kader van een verandering in regelgeving. Per 1 januari 2008 is het Meststoffenbesluit overgeheveld naar het Uitvoeringsbesluit Meststoffenwet en daarmee ok de overheveling van Beschikking analysemethoden meststoffe

Practical estimation of the uncertainty of analytical measurement standards

Nowadays, a lot of time and resources are used to determine the quality of goods and services. As a consequence, the quality of measurements themselves, e.g., the metrological traceability of the measured quantity values is essential to allow a proper evaluation of the results with regard to specifications and regulatory limits. This requires knowledge of the measurement uncertainties of all quantity values involved in the measurement procedure, including measurement standards. This study shows how the uncertainties due to the preparation, as well as the chemical and compositional stability of a chemical measurement standard, or calibrator, can be estimated. The results show that the relative standard uncertainty of the concentration value of a typical analytical measurement standard runs up to 2.8% after 1 year. Of this, 1.9% originates from the preparation of the measurement standard, while 2.0 and 0.53% originate from the chemical and compositional stability during storage at -20 A degrees C. The monthly preparation of working calibrators stored at 4 A degrees C and used on a weekly basis, results in an additional standard uncertainty of the analyte concentration value of 0.35% per month due to compositional stability. While the preparation procedure is the major contributor to the total measurement uncertainty, the uncertainties introduced by the stability measurements are another important contributor, and therefore, the measurement procedure to evaluate stability is important to minimize the total measurement uncertainty

Sub-chronic toxicity study in rats orally exposed to nanostructured silica

Synthetic Amorphous Silica (SAS) is commonly used in food and drugs. Recently, a consumer intake of silica from food was estimated at 9.4 mg/kg bw/day, of which 1.8 mg/kg bw/day was estimated to be in the nano-size range. Food products containing SAS have been shown to contain silica in the nanometer size range (i.e. 5 – 200 nm) up to 43% of the total silica content. Concerns have been raised about the possible adverse effects of chronic exposure to nanostructured silica

A Targeted Search for Point Sources of EeV Photons with the Pierre Auger Observatory

Simultaneous measurements of air showers with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for EeV photon point sources. Several Galactic and extragalactic candidate objects are grouped in classes to reduce the statistical penalty of many trials from that of a blind search and are analyzed for a significant excess above the background expectation. The presented search does not find any evidence for photon emission at candidate sources, and combined p-values for every class are reported. Particle and energy flux upper limits are given for selected candidate sources. These limits significantly constrain predictions of EeV proton emission models from non-transient Galactic and nearby extragalactic sources, as illustrated for the particular case of the Galactic center region

Zilver nanodeeltjes in textiel

Nanodeeltjes worden in steeds meer producten toegepast. Zo wordt 'nanozilver' toegepast in textiel vanwege hun antibacteriële eigenschappen. Het is echter onzeker of de toepassing van dergelijke nanodeeltjes risico's voor de consument en het milieu met zich meebrengt. Natuur & Milieu heeft daarom verzocht een aantal textieproducten te onderzoeken op de aanwezigheid van zilver nanodeeltjes en het uitspoelen van deze deeltjes tijdens het wassen

Nano-silica in selected food items

In this study the presence of silica nanoparticles in a number of food products is analysed

Nanodeeltjes in cosmetica

Tegenwoordig worden in steeds meer producten nanodeeltjes toegepast vanwege hun speciale eigenschappen die de functionaliteit van een product kunnen verbeteren. Over de definitie van nanodeeltjes of nanomaterialen wordt momenteel discussie gevoerd. In dit rapport wordt de term nanodeeltje gebruikt in overeenstemming met de oorspronkelijke definitie, in minimaal een dimensie kleiner dan 100 nm. Nanodeeltjes worden o.a. toegepast in diverse reinigingsmiddelen en onderhoudsspray's, in sommige soorten textiel, in cosmetica en zonnebrandcremes. Het onderzoek naar mogelijke risico's van het gebruik van nanodeeltjes is echter nog in volle gang en het is dan ook nog onduidelijk of de toepassing van deze deeltjes in consumentenproducten een risico voor de consument met zich meebrengt of niet. Natuur & Milieu heeft gevraagd om een aantal cosmetica producten te onderzoeken op de aanwezigheid van anorganische nanodeeltjes. Het doel is vast te stellen of in bepaalde productem anorganische nanodeeltjes worden toegepast, en zo ja, wat de samenstelling ervan is. Indien mogelijk dient eveneens te worden vastgesteld of deze deeltjes voorzien zijn van een coating. Nanodeeltjes in cosmetica zijn soms voorzien van een coating, enerzijds om ze beter te kunnen dispergeren in het product, anderzijds als beschermend laagje bij de absorptie van zonlicht door anorganische nanodeeltjes

Chemical aspects of drinking water chlorination

Applied Science