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  • White Paper: How to minimize standard deviations by correct sample preparation

    Modern analytical methods increase precision and push detection limits to make even the smallest traces of sample components detectable. Despite this development sample preparation, which is carried out prior to the actual analysis, is frequently neglected. Errors caused by lacking accuracy in sample preparation have a much bigger impact than errors made during analysis. Just like an iceberg which is mostly hidden under water, only a small part of the sum of errors is perceived whereas the major part of potential errors is not taken into account (fig. 1). One of the reasons may be the fact that sampling and sample preparation have always been done in a traditional way which has become a routine over the years and is no longer considered as having a critical influence on the subsequent analyses.

Reports applicativi (34)

  • Determinazione delle micotossine nelle noci

    Macinazione preliminare e fine
  • Dalla pianta di cacao alle barrette di cioccolato

    Cosa sarebbe il mondo senza cioccolato? La produzione di cioccolato è un processo abbastanza elaborato, di cui un requisito fondamentale è il controllo qualità delle materie prime. La strada dalle piante di cacao alle barrette di cioccolato è lunga. A causa delle molte fasi di lavorazione, raccolta, fermentazione, essiccazione, pulitura, torrefazione, pre-frantumazione e infine la macinazione dei pennini di liquore di cacao da cui vengono estratti cacao in polvere e burro di cacao – ci possono essere differenze significative nella qualità. Il processo di controllo della qualità non comprende soltanto test di pericolosità del prodotto (es. funghi, contaminazione da metalli pesanti) o di altri ingredienti (contenuto di grassi e carboidrati) ma anche la riduzione delle dimensioni per test sensoriali sul liquore di cacao. Questo è importante perché il palato umano percepisce in modo sgradevole particelle più fini di 30 microns. 
  • Determinazione dei grassi negli alimenti e nei mangimi

    Macinazione di campioni a elevato contenuto lipidico
  • Energia rinnovabile

    Residui di legno dalle lavorazioni forestali e dalla lavorazione del legno sono solitamente trasformati in trucioli di legno. Questi possono essere utilizzati in modo diverso, in base al tipo di legno, alla corteccia, all’umidità residua, ad esempio come materia prima per pannelli truciolari o come substrato per la coltivazione di funghi. La maggior parte, comunque, viene utilizzata per la produzione di energia. La qualità del legno cippato può variare notevolmente, a seconda della sua origine e condizione. Il commercio e l’industria sono interessati alla percentuale di materia secca e al potere calorifico del legno cippato, così come il valore del prezzo dipende dal contenuto di acqua nel prodotto. Con il risultato dell’analisi che rappresenta un importante fattore economico, anche la preparazione del campione in modo rappresentativo e riproducibile ottiene importanza
  • Le barrette di cereali sono veramente sane?

    I produttori alimentari spesso promuovono i propri prodotti come “light” o come, nel caso delle barrette di cereali come “sane”. Se questo è effettivamente vero, non può che essere verificato analizzando i valori nutrizionali, una procedura che costituisce una parte importante nel controllo della qualità alimentare. I valori di grassi, acidi grassi saturi, zuccheri e sale stampati sulle confezioni rappresentano una media del contenuto di ogni sostanza e si riferiscono a 100 ml in 100 g di prodotto. Le barrette di cereali sono costituite da un mix eterogeneo di ingredienti (noci, uvetta, fiocchi d’avena, ecc..) pertanto è necessaria una completa omogeneizzazione del campione per ottenere risultati d’analisi significativi.
  • Mulino a taglienti SM 300 – Affinamento di un sistema di macinazione ben affermato

    I mulini a taglienti vengono utilizzati in diverse aree della preparazione dl campione alle analisi successive. Tipiche applicazioni includono la riduzione di combustibili da rifiuto, la macinazione di campioni di biomasse per ricerche nell’ambito delle energie rinnovabili, il controllo dei prodotti nell’abito delle normative RoHS and WEEE, o nel recupero dei materiali preziosi – la varietà di campione è notevole.
  • Perfetta omogeneizzazione con il GRINDOMIX GM 300

    La diversità degli alimenti con le spesso differenti proprietà dei prodotti rappresenta una reale competizione per i laboratori di analisi alimentari. Per le attuali analisi, i campioni – che possono essere molto tenaci a seconda della loro durezza o umidità – necessitano di essere ridotti e omogeneizzati in modo sufficientemente fine. I mulini a coltelli GRINDOMIX RETSCH sono lo strumento ideale per venire incontro ai complessi requisiti richiesta dalla preparazione di alimenti. Il
    modello GM 200 è ormai consolidato per l’omogeneizzazione di piccoli volumi di campione fino a 700 ml. Per volumi maggiori RETSCH adesso offre il nuovo GRINDOMIX GM 300 con una camera di macinazione del volume di 5000 ml.
  • Utilizzo del Cryomill per campioni con componenti volatili

    Per la riduzione di dimensioni di molti materiali è consigliabile utilizzare un mulino criogenico invece di un mulino che opera a temperature ambiente. Il campione viene infragilito con l'azoto liquido che migliora il suo comportamento di rottura quando viene sottoposto a impatto, pressione e attrito. Inoltre, in questo modo vengono conservati i componenti volatili del campione. Il mulino Cryomill non solo è il mulino criogenico più sicuro e moderno sul mercato ma fornisce anche eccellenti risultati di macinazione.
  • Análisis de sustancias nocivas en muestras biológicas

    La molienda criogénica facilita la preparación de muestras de origen animal
  • La Fragmentación

    Por lo general se asocia a la noción "fragmentación", el machacamiento, de sustancias sólidas mediante fuerza mecánica. Pero también la división de líquidos en gotas o de gases en bollas representa un proceso de fragmentación.
  • La nueva generación de molinas planetarios de bolas

    Los más precisos resultados de trituración en el más breve tiempo se consiguen con los nuevos molinos planetarios de bolas, de Retsch. Con el PM100 y el PM200, Retsch presenta una nueva generación de molinos planetarios de bolas con uno o dos unidades de trituración, que establecen nuevos estándares de rendimiento en este segmento de la producción.
  • Materias primas renovables a la vanguardia

    Particularidades de la preparación de plantas
  • Molienda ultrarrápida y ultrafina

    El nuevo molino ultracentrífugo ZM 200 de RETSCH es un molino de rotor no sólo extremadamente rápido y cuidadoso con el material molido, sino también de uso universal gracias a su amplia gama de accesorios.
  • Eiskalt Zerkleinert

    Die meisten Probenmaterialien lassen sich durch die Wahl des geeigneten Zerkleinerungsgerätes problemlos mahlen. Die Beanspruchungsmechanismen wie Prall, Druck, Scherung, Schneiden, Reibung reichen bei Raumtemperatur aus, um das Material auf die benötigte Partikelgröße zu zerkleinern. Was aber kann man tun, wenn die mechanische Beanspruchung allein nicht ausreicht, um das Probenmaterial in möglichst kleine Partikel zu überführen? Eine Lösung dieser Problematik bietet der Einsatz von Flüssigstickstoff, der das Bruchverhalten solcher Materialien begünstigt.
  • Kolloidvermahlungen zur Erzeugung von Nanopartikeln

    Nanoteilchen, d.h. Partikel mit einem Durchmesser von weniger als 100 Nanometer, werden seit vielen Jahren von Wissenschaftlern erforscht. Zum einen lassen sie sich im „Bottom-up“ Verfahren aus Atomen oder Molekülen synthetisieren. Im “Top-Down“ Verfahren hingegen werden größere Partikel, z.B. mit Hilfe von Labormühlen, zerkleinert. Kleine Partikel weisen durch das extrem vergrößerte Verhältnis von Oberfläche zu Volumen erhöhte Oberflächenladungen auf, so dass die Partikel elektrostatisch zueinander gezogen werden. Daher können Nanopartikel nur durch Nassvermahlung (Kolloidvermahlung) erzeugt werden.
  • Komplexe Proben homogenisieren

    Messermühlen zur professionellen Probenvorbereitung im Labor

    Nahrungsmittel treten in sehr unterschiedlichen Formen und Konsistenzen auf und sind i. d. R. inhomogen. Für die Analytik werden jedoch homogene und repräsentative Proben benötigt, um aussagekräftige Ergebnisse zu erzielen. Im Rahmen der Probenvorbereitung müssen die oft sehr komplexen Proben also homogenisiert und auf eine hinreichende Partikelgröße zerkleinert werden. Dabei können die Materialien sehr stark in Bezug auf Härte und Feuchte variieren. Um den vielschichtigen Anforderungen der Probenvorbereitung von Lebensmitteln gerecht zu werden, bietet sich der Einsatz von Messermühlen an.
  • Neue Messermühle setzt Standards

    Die Messermühle GRINDOMIX GM 300 eignet sich für die schonende Zerkleinerung und Homogenisierung von Lebensmitteln. Sie kann Probenvolumina von bis zu 4,5 l schnell und reproduzierbar verarbeiten. Mit vier scharfen, robusten Klingen und einem leistungsstarken Motor mit bis zu 3 kW Spitzenleistung ist sie ideal ausgerüstet zur Homogenisierung von Substanzen mit hohem Wasser-, Öl- oder Fettanteil ebenso wie zur Zerkleinerung trockener, weicher, mittelharter und faseriger Produkte.
  • Perfekte Homogenisierung von Lebensmittelproben

    Nahrungsmittel treten in sehr unterschiedlichen Formen und Konsistenzen auf und sind in der Regel inhomogen. Für die Analytik werden jedoch homogene und repräsentative Proben benötigt, um aussagekräftige Ergebnisse zu erzielen. Für diese Aufgabe sind die Messermühlen Grindomix GM 200 und GM 300 von RETSCH die idealen Instrumente.
  • Probenvorbereitung von Böden

    Bestimmung von anorganischen Inhaltsstoffen in Bodenproben

    In Industrienationen mit hoher Besiedlungsdichte und einem begrenzten Angebot an Industrie- und Gewerbegebieten unterliegt die Nutzung von Gebäuden und Flächen einem dauerhaften Wandel. Daher sind Bodenuntersuchungen für Investoren, Behörden und Privatpersonen unumgänglich. Umweltanalytische Untersuchungen bilden die Basis, um Gefährdungen aufzuzeigen und damit Menschen und eingesetztes Kapital zu schützen. Bei SGS Institut Fresenius in Herten werden bis zu 400 Bodenproben am Tag aufgearbeitet und analysiert. Hierbei wird sehr genau darauf geachtet, dass geltende Normen und Verordnungen eingehalten werden. In Deutschland gilt die BbodSchV, wobei die Analytik auch auf die Vorschriften anderer Länder angepasst wird.
  • Probenvorbereitung von Futtermitteln für die NIR Analytik

    In der Haltung von Nutztieren hat die Qualität der Futtermittel einen bedeutenden Einfluss auf die Produktivität. Darüber hinaus bringt Tiernahrung die am stärksten schwankenden Kosten, die mit der Haltung von Nutztieren verbunden sind, mit sich. Deshalb ist eine zuverlässige Analyse von Futtermitteln und Futterinhaltsstoffen der beste Weg, ein ausgewogenes Fütterungsprogramm zu gewährleisten und gleichzeitig die Wirtschaftlichkeit des Betriebs zu optimieren.
    Die Nah-Infrarot-Spektroskopie ist die wichtigste Analysenmethoden bei Futtermitteln zur Bestimmung von Daten wie Proteingehalt, Feuchte, Fett und Asche. Der Vorteil gegenüber klassischen Methoden wie z.B. Kjeldahl ist, dass mehrere Parameter gleichzeitig bestimmt werden können. Außerdem ist die NIR-Spektroskopie ein schnelles Verfahren, das kein Verbrauchsmaterial und keine Reagenzien benötigt. Deshalb wird sie immer dort eingesetzt, wo ein hoher Probendurchsatz und eine große Flexibilität erforderlich sind. Die Identifizierung und Qualifizierung der Rohstoffe sowie die quantitative Analyse von Fertigprodukten können innerhalb weniger Sekunden durchgeführt werden, um höchste Produktqualität und -sicherheit zu gewährleisten.
    Eine viel diskutierte Frage im Zusammenhang mit der NIR-Spektroskopie ist die Notwendigkeit der Probenvorbereitung. Der Anwender steht häufig vor dem Problem zu entscheiden, wann eine Probenvorbereitung erforderlich ist und wann nicht.
  • Pesticide analsis of soil - not without sample preparation

    The use of pesticides in agriculture makes it possible to plant extensive mono cultures and often leads to substantial yield increases of food and feed crops. Demand and application have grown steadily over the years, leading to increased contamination of the soil due to the toxic nature of pesticides. Soils save the toxins and their decomposition products so that wildlife is also affected by them. Among the undesired side effects are damages to useful plants and insects like bees. The wind carries pesticides to uncontaminated areas such as fields used for organic farming. Rain also transports the chemicals away from their original area of application to waters and groundwater. Although in most cases the limit values for particular pesticides and their decomposition products are not exceeded, the cumulative effect on humans and animals has not been thoroughly investigated so far. The possible accumulation of pesticides in the food chain could be a source of health hazards; therefore strict quality control of soils is indispensable.
  • Sample Division of Large Volumes

    Representative sampling of large sample volumes is an integral part of the physical and chemical analysis of bulk goods and has a decisive influence on the quality of the results. Extraction of a sample from the bulk is not always carried out in a way to ensure representativeness. This is a widespread flaw in the quality control process with a negative impact on the subsequent analysis results. Therefore, more attention should be paid to the correct sampling procedure. Sample division is often considered as a labor-intensive process which not always leads to representative results. RETSCH provides some convenient solutions which help to improve working conditions and thereby the quality of the sampling process.
  • Quick and reproducible grinding of feedstuff

    Grain, compound feeds or feed pellets occur in a variety of forms; compound feeds are usually inhomogeneous. Feedstuff is analyzed, for example, to determine the nutritional value, to detect hazardous substances or genetically modified ingredients. To ensure meaningful and reliable analysis results, representative and homogeneous samples are required. Therefore, sample preparation involves homogenization and size reduction of the material to a defined particle size. RETSCH laboratory mills are perfectly suited for this process.
  • Detection of genetically modified organisms (GMO) in food and feed

    Genetic engineering opens up new possibilities in areas such as medical research, development of alternative fuels or global food supply. It is used to modify the characteristics of plants in order to increase the crop yield, improve defense against predators, pesticides or draught, but also increase concentrations of essential vitamins. However, with regards to food the use of genetic engineering is a fairly controversial issue. Moreover, food and feed stuff are subject to rigorous quality control processes to prevent humans and animals from potential harm.
  • Sample Preparation and Analysis of Arsenic in Rice

    Considerable care must be taken when analyzing a sample like rice in order to achieve an accurate result. The major source of error when analyzing a bulk material comes not from the analytical measurement itself, but from the sample handling, i.e., sampling, sample division, grinding, digestion, etc.
  • Renewable energies on the rise

    Sample preparation of vegetable-based raw materials with laboratory mills

    Thanks to the increasing usage of biomass as a source of energy, the analysis of these materials in the context of R&D and quality control gains importance, too. Due to the complex properties of plant materials, adequate sample preparation can be rather a challenge.
  • Sample preparation of feeds and forage for NIR analysis

    The feed quality has a decisive influence on the productivity of livestock farming. However,  high-quality forage considerably adds to the costs of stock breeding. Consequently, economic considerations focus on the quality and quantity of the components used in the production process. This includes reliable analyses of feedstuff and ingredients from receipt of goods to final inspection as the best way to ensure a balanced feeding of the animals while keeping cost and profit orientation in focus.
    Near Infrared Spectroscopy (NIR) is the most important analytical method for the determination of protein content, moisture, fat and ash in feeds and forage. The advantage over classical methods such as Kjeldahl is the simultaneous determination
    of several parameters. Moreover, NIR spectroscopy is a quick method, which requires neither consumables nor reagents.
  • White Paper: Representative Analysis Results Require Adequate Sample Preparation

    A faultless and comparable analysis is closely linked to an accurate sample handling. Only a sample representative of the initial material can provide meaningful analysis results. Rotating dividers and rotary tube dividers are an important means to ensure the representativeness of a sample and thus the reproducibility of the analysis. Correct sample handling consequently minimizes the probability of a production stop due to incorrect analysis results. Thus correct sample handling is the key to effective quality control.
  • CryoMill - Cryogenic grinding was never more convenient or efficient

    Some sample materials have properties which make size reduction at ambient temperature impossible. If, for example, very elastic materials need to be ground or volatile components have to be preserved for further analysis, it is essential to carry out cryogenic grinding. The use of liquid nitrogen helps to embrittle the sample, thus improving its breaking properties, and preventing volatile substances from escaping due to the frictional heat produced by the grinding process.
  • Powerful Cutting Mill

    The SM 300 excels especially in the tough jobs where other cutting mills fail. It has a freely selectable speed range from 700 to 3,000 rpm with high torque. The mill is convenient to operate and easy to clean. Reliable and extremely efficient sample preparation in the laboratory is now guaranteed with the SM 300.
  • Preparation of Soil, Sewage Sludge and Sediment Samples in a Wastewater Treatment Laboratory

    The preparation of a mixture of organic and inorganic samples holds some difficulties: whereas sand, clay and stones can usually be ground to homogeneous samples with suitable laboratory mills, the high energy input can cause samples with organic components such as fat or starch to cake. Carsten Bunn, a laboratory technician at the waste water treatment laboratory BRW, has to deal with this problem every day. He treats samples which are taken from the sand traps of the wastewater treatment plants and consist of exactly that mixture. The sediments of household and industry waste water not only contain sand, clay or leaves but anything that people nowadays dispose of through the sewer system: cellulose, hair and especially food residues.
  • Representative results require adequate sample preparation

    The following situation is typical for many production plants: After a routine quality check, the production process is stopped or an already produced batch is suspended, because the analysis results were not within the relevant critical values. But does the tested product really deviate from the specifications? The quality control managers are convinced of this because modern analysis instruments provide results with very low tolerances. The sample in question was tested several times and the result was confirmed. The question is why the product does not match the specifications although the production parameters have not been changed in any way.
    The possibility that the tested product is indeed deficient cannot be excluded. However, it is often not the product itself which causes irregular analysis results but a lack of understanding of the steps which come before the analysis.
  • Air Jet Sieving of Bulk Materials

    Particle size analysis and particle size distribution are important criteria for the quality  control of bulk materials. In a running production process, the results of a quality check must be available quickly to allow for immediate adjustment of the production parameters. Depending on the expected particle size and sample volume, different sieving methods and sieving machines are suitable for analysis. The method used for particle size analysis is primarily determined by the fineness of the material to be sieved. For dry sieving of samples with particle sizes below 40 microns, air jet sieving is the method of choice.

Referenze (6)

Test Reports (56)