echemi logo
Product
  • Product
  • Supplier
  • Inquiry
    Home > Active Ingredient News > Drugs Articles > The importance of pre-treatment of laboratory samples

    The importance of pre-treatment of laboratory samples

    • Last Update: 2020-07-15
    • Source: Internet
    • Author: User
    Search more information of high quality chemicals, good prices and reliable suppliers, visit www.echemi.com

    the importance of pre-treatment of laboratory samples
    1the importance of pre-sample processing
    whether for chemical analysis of samples or in biological engineering, sample separation, purification is an essential pre-treatment stepThe quality of the sample pre-treatment will directly affect the resultsaccording to lc-GC Intmagazine's statistics on more than 1,000 laboratories around the world, modern automated analytical instruments, which take 61% of the total analysis process, make analysis simple and fastHowever, many laboratories with modern analytical instruments still use old, cumbersome sample pretreatment methodsPre-sample processing has become a bottleneck in modern analysis, which seriously hinders the analysisTherefore, to improve efficiency, it is necessary to solve the problem of sample pre-treatmentaccording to the same statistical report can be seen in the entire chromatography process, sample pre-processing generated errors of large, up to 30%, if combined with operational errors, human factors accounted for nearly 50% of the source of error in other words, if we can solve the human error caused by the error, the probability of analysis error is reduced by halfdifferent testing methods on the sample pre-treatment requirements are also differentIts main purposes are:1separate the target compound from the matrix,2Remove as many components as possible that interfere with the analysis of the target compound,3Remove the substance that causes damage to the analysis instrument as much as possible,4Concentrate the target compound to reach the detection floor of the analytical instrument, and5Adjust the pH and ion strength of the sample to meet the testing requirements of the analytical instrument2.
    The basic principle of solid phase extraction2.1adsorption target compound mode
    in the adsorption target compound pattern, the adsorption force of the SPE column to the target compound is greater than the sample base solutionAs shown in the figure below, when the sample passes through the SPE column, the target compound is attached to the solid filler surface, and most of the other sample components pass through the column with the matrixThe target compound can be washed off with an appropriate solventFor convenience, we refer to this extraction pattern as "adsorption target compound mode" or "target compound adsorption mode" In this extraction mode, the SPE column, while adsorption of the target compound, may also absorb some interferences that have an effect on the analysisTherefore, before the target compound is eluted, the SPE column is washed to effectively remove these interferencesadsorption target compound pattern can be divided into the following steps: SPE column pre-treatment (discarded column liquid) sample sPE column (discarded column liquid) SPE column washing and drying (discarded column liquid) target compound washing and drying (discarding column liquid) 2.2 adsorption impurity mode
    when the sample passes through the SPE column, the sample is absorbed by the sample We call it the "absorption impurity mode" or "impurity adsorption mode", which is used for sample purification In this extraction mode, the components of the sample after the column are collected together with the components of the column washing Unlike the target compound adsorption mode, the column washing in the impurity adsorption mode is to wash off the target compound that remains on the SPE column and keep the impurities on the SPE column can be divided into the following steps in the adsorption impurity mode: SPE column pre-treatment (discarding column liquid) sample sPE column (collected column liquid) SPE column washing (collecting column liquid into the above-mentioned test tube) 3.
    The main force sequester in solid phase extraction 3.1
    non-polar force in solid phase extraction
    non-polar force in solid phase extraction, which is produced between the hydrocarbon bond on the functional group of the solid phase extraction material and the hydrocarbon bond of the compound in the sample This force is both the familiar Van der Waal gravity or scattering force Since organic molecules are more or less present with this non-polar structure, non-polar forces are often used to absorb and separate compounds with non-polar structures from the sample matrix the non-polar SPE column used by zui do is a carbon chain composed of eighteen carbon, commonly known as C18 columns Because C18 materials are widely used in liquid chromatography, their properties are also well understood and are widely used in SPEs Generally speaking, the non-polar SPE column is more versatile Therefore, it is suitable for simultaneous extraction of a variety of different chemical properties of compounds However, its selectivity is worse than polarity or ion exchange force generally, non-polar SPE columns are more suitable for extracting target compounds that are non-polar and medium polar from polar substrates for target compounds that are adsorbed on non-polar SPE columns by non-polar force, can be eluted with solvents of non-polar properties, such as cyclic hexane Even methanol, which is more polar, has sufficient non-polar force to elude many compounds 3.2
    polar forces in solid phase extraction polar forces in solid phase extraction can occur in many solid phase extraction materials and compounds in samples Polar forces include: hydrogen bonds, even-effort/even-effort, inducing even-to-do, and so on Such as: hydroxyl, amino, pyridoxa, carbide, aromatic rings and oxygen, nitrogen, sulfur, phosphorus and other hybrid atom groups Among them, the hydrogen bond is a common polar force non-polar matrix environment is conducive to polar action between adsorbents and target compounds, polar environment is conducive to the destruction of polar forces between adsorbents and target compounds, and the high intensity of environmental ions is not conducive to polar forces between adsorbents and ananalysis it is worth pointing out that all SPE columns made of bonded silicone have polarity because the bonded silicone itself has a certain number of non-bonded -OH groups (no tails) This polarity function is more obvious in non-polar solvents are commonly used in polar extraction of elution solvents are: methanol, water, THF, isopropanol, acetic acid, acetylene, acetone, amines, high ion strength buffer or the above-mentioned solution mixture 3.3
    ion action force in solid phase extraction
    Ion action force occurs between the sample compound with the opposite charge and the SPE filler body For organic compounds, there are two types of compound symtocences that can produce ion exchange: 1 the organ group (with positive charge) that can generate cations (with positive charge) 2 The organ group (with negative charge) that can generate an ion (with negative charge) the common cations of the organ group includes: bo, Zhong, uncle, butamine common anions of the organ group include: carbide, sulfonate, phosphoric acid, etc to properly use the ion exchange column for solid phase extraction, attention must be paid to controlling the extraction environment In order to effectively use ion switching to adsorption of the target compound to the solid-phase column, two conditions must be met: 1 The pH of the environment must enable the analyte and the adsorbent to have the opposite charge 2 The environment must not contain high concentrations of competing compounds with the same charge as the analyte
    This article is an English version of an article which is originally in the Chinese language on echemi.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to service@echemi.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

    Contact Us

    The source of this page with content of products and services is from Internet, which doesn't represent ECHEMI's opinion. If you have any queries, please write to service@echemi.com. It will be replied within 5 days.

    Moreover, if you find any instances of plagiarism from the page, please send email to service@echemi.com with relevant evidence.