Biological sample preparation method for XRF energy dispersion spectrometer

In recent years, biological sample preparation methods for XRF energy dispersion spectrometers have been used for food and various biological materials (such as plant, animal and human tissues, bones and fluids). Since most of the elements of interest are present in concentrations of ug/g and ng/g, great care should be taken to sample these materials to avoid contamination. Trace amounts and other elements of samples during contamination sampling may come from the environmental sampling operation itself, including dust in the air and sampling tools. Types of pollutants that may come from the laboratory atmosphere. The minimum requirement to prevent contamination by air dust is to have a clean work area to handle the sample. This can be provided by a laminar flow clean air workbench or at least by cleaning the glove box. Laminar flow table can never be turned off). Non-metal tools and laboratory materials should be used. Some examples of reagents leached from container walls of elements that may be another source are given. Special precautions should be taken to avoid changes in the average sample composition due to water loss. This is often a difficult experience with small tissue samples, such as biopsy samples. Necessary precautions Sample types should be stored in a closed system or frozen immediately after sampling. Also, chemical processes such as hydrolysis, REDOX reactions, fermentation, or photochemical reactions may cause changes in the average composition.

Biological sample preparation method for XRF energy dispersion spectrometer

During transportation to the laboratory, the sample should be kept cool (4 درجة مئوية) if necessary for transportation. Just a few hours. Otherwise, it should be frozen. For long-term storage, deep freezing (as low as -18 درجة مئوية) مهم. Containers made of non-wettable materials, such as Teflon, are recommended for high pressure use of polyethylene, مادة البولي بروبيلين, synthetic quartz. Surface pretreatment of beakers and containers can be carried out by chelating reagents, such as EDTA(1%6 solution), followed by the addition of inorganic acid (ultra-pure HNO3), and then thoroughly rinsed with double distilled water.

Biological materials are usually heterogeneous. When handling solid samples, they should be dried, and before preparation, it may be necessary to conduct pulverization, homogenization, and homogeneity test samples for measurement. Body fluid samples form a suspension or emulsion. For these, separation or homogenization must be considered. Various treatment methods for biomaterials include drying, lyophilization, ashing, and wet treatment for digestion.

It is usually dried in the oven or freeze-dried as a method of pre-concentration. Sample before measuring. It is important to control the temperature while the oven is drying. Some plant materials (cabbage, على سبيل المثال) will break down at temperatures higher than 85C. Do not dry biological materials at temperatures higher than 100 درجة مئوية. After drying or freeze-drying, the material is next ground and homogenized, then granulated or the equal sample is used for wet digestion (ملحوظة: biological and geological materials should not be dried in the oven at the same time). The oven should be carefully cleaned before drying the biological material.

Biological sample preparation method for XRF energy dispersion spectrometer

Ashing is used to remove organic substrate. Ashing methods include dry ashing by heating in a Muffle furnace (at 450-500 درجة مئوية) and wet ashing the mixture with oxidizing acids. Ashing the loss of volatile elements in a furnace at 450-500° C is not recommended. Dry ash is usually preferred for wet ashing with a mixture of acids (على سبيل المثال. HNO3 + HCI) as it reduces the loss of trace elements and is faster and more rapid. It is often possible to remove organic matter more thoroughly. Wet ashing can be done in the “open air method “, using an electric heating 1 and a round-bottomed flask with or without air-cooled reflux. When reducing the many system errors in the decomposition of organic materials, dissolution is carried out in a PTFE pressure projectile. Pressure decomposition requires small amounts of acid and prevents the loss of volatile elements (على سبيل المثال. زئبق, مثل, Se, ر, 1). Disadvantages Pressure bombs are designed to strictly limit the sample weight to 0.5g for safety reasons (ملحوظة: Read the manual carefully and follow the instructions before using a PTFE bomb. In recent years, wet digestion plus 1 heater has been facilitated by the introduction of laboratory microwave digestion technology. Microwave energy is absorbed directly by the acid and biomaterial, resulting in faster sample decomposition. The digestion method should be optimized and the recovery rate of elements and the precision of the process should be thoroughly tested. After wet digestion, trace amounts of the metal can be pre-concentrated.

The simplest way to prepare biological samples for XRF is to dry and pulverize the material. لكن, the detection limits are not sufficient to identify elements in concentrations below a few ppm. In this case, wet digestion is best followed by pre-concentration. The pre-concentration technique most commonly used for water analysis can also be used for biological samples, such as ion exchange in granular bead form using Chelex 100 resin, precipitation with organic reagents (على سبيل المثال. NaDDTC, APDC, DBDTC, PAN) to form strong insoluble chelates with many transition metal ions. The precipitate is filtered through a membrane or nuclear pore filter and dried and measured taking one gram of dried plant material (or about 5 grams of fresh material) for analysis with 25 ml of high purity concentrated nitric acid heated until brown smoke nitrogen oxides disappear (=40 minutes). After cooling (do not pour perchloric acid into warm water 24) acidic solution) add 10 ml of 70% perchloric acid and heat the solution again until it becomes colorless and transparent (=40 minutes). Once cooled, add 25 ml of double diluent distilled water and adjust the pH to about 5 with gaseous NH3. This is done by placing a beaker filling the bottom with the concentrated ammonium hydroxide from the solution in the dryer. If ammonia is used in the fresh dryer, the pH adjustment will take about 1 hour. During this process, check every 15 minutes with a pH test strip to measure the pH atBetween 3.5-6.0. Trace pre-concentration uses the metal to be determined (الحديد, الزنك, النحاس, الرصاص, في), precipitating the metal ions with NaDDTC solution. A cadmium carrier (10 ml of 10 ppm solution) can be added to facilitate quantitative precipitation. Usually 10-15 ml of 2%NaDDTC aqueous solution (freshly formulated) is added, then the resulting precipitate is left to rest for about 20 دقائق. Filter the resulting precipitate through a nuclear pore filter, dry and measure directly. The digestive mixture contains 10 grams of sodium molybdate (as a catalyst), dissolved in 150 ml of double distilled water and 150 ml of H2SO4 (cone). After cooling, 70% of 200ml is added to perchloric acid. Place 1 gram freeze-dried or 5 grams of fresh blood or tissue into a round-bottomed flask (150 ml volume) و 40 ml of the digestive mixture. The mixture and sample are then heated at 160C for about 1 hour. The solution obtained should be clear. After cooling (never pour perchloric acid into a warm acidic solution) and diluting it six times with water, the solution should be boiled to remove the chlorine. After cooling, use gaseous NH3 to about 5(see method above). For pre-concentration of trace metals use NaDDTC solution to determine the (الحديد, الزنك, النحاس, الرصاص, في) precipitation of metal ions (الحديد, الزنك, النحاس, الرصاص, في) precipitation. A cadmium carrier (10ml of 10 ppm solution) can be added to facilitate quantitative precipitation.

Biological sample preparation method for XRF energy dispersion spectrometer

10-15 ml of 2%NaDDTC aqueous solution (freshly prepared) is usually added and the resulting precipitate is left to rest for about 20 دقائق. Filter the resulting precipitate through a nuclear pore filter, dry and measure directly