You are here: Home > News

Requirements for samples sent by laboratory analytical instruments

Time:2018/10/24   Pageviews:0    Share:
  This is an article about Requirements for samples sent by laboratory analytical instruments. If you are interested, please contact us!

Every day, the laboratory uses instruments to test various samples, and we all know that different instruments have very different requirements for samples. Then let's take a look at the specific requirements of the laboratory analytical instruments for the samples to be sent.

Nuclear magnetic resonance spectrometer

(1) The purity of samples to be inspected should generally be >95%, without impurities such as iron filings, dust, filter paper and hair. The amount of sample to be provided for general organic matter: 1H spectrum > 5 mg, 13 C spectrum > 15 mg, and the amount of sample required for the polymer should be appropriately increased. 2ml crimp neck vials

(2) The instrument configuration can only carry out liquid sample analysis, and the sample is required to have good solubility in a certain deuterated solvent. The sampler should first select the solvent to be used. The deuterated solvents commonly used in this room are chloroform, heavy water, methanol, acetone, DMSO, benzene, o-dichlorobenzene, acetonitrile, pyridine, acetic acid, trifluoroacetic acid.

(3) Please ask the sampler to provide the possible structure or source of the sample. If you have special requirements (such as temperature, spectrum width, etc.) please explain.

2. Infrared spectrometer

In order to protect the instrument and ensure the quality of the infrared spectrum of the sample, the samples sent to the instrument for analysis must be:

(1) The sample must be pre-purified to ensure sufficient purity;

(2) The sample must be dehydrated in advance to avoid damage to the instrument and avoid interference of the water peak on the sample spectrum;

(3) Samples that are easy to deliquesce, please place your own dryer;

(4) For volatile, sublimated, heat-labile samples, please cover and close the container with a sealing cap or stopper, and must be indicated on the sample analysis task list;

(5) For toxic and corrosive samples, the user must install it in a sealed container. The sample must be marked on the obvious location of the vial label and on the analysis task list;

3. Organic mass spectrometer

It is suitable for the analysis of liquid and solid organic compound samples with a relative molecular mass of 50~2000μ. The sample should be as pure a single component as possible.

4. Gas chromatography-mass spectrometer
The gas chromatograph uses a capillary column (a packed column cannot be used).

The sample entering the GC oven must be fully vaporized over the operating temperature range of the column.

5, liquid chromatography-mass spectrometer

(1) Flammable, explosive, poisonous, corrosive samples must be noted.

(2) In order to ensure accurate and reliable analysis results, the sample is required to be completely dissolved, and no mechanical impurities are required; please refer to the solvent for the sample that is not formulated into a solution, and the concentration of the sample that has been formulated into the solution.

(3) Please provide the structural formula, molecular weight or functional group of the sample as much as possible in order to select the ionization method; if there are special requirements, please provide specific experimental conditions.

(4) When using liquid chromatography-mass spectrometry, all buffer systems should be formulated with volatile buffers such as acetic acid, ammonium acetate, tetrabutylammonium hydroxide, etc. For those who require quantitative analysis, please provide standard reference.

6. Flight time mass spectrometer

(1) Specimen type, composition and sample size

The instrument is good at measuring peptides and proteins, and can also measure other biological macromolecules, such as polysaccharides, nucleic acids and high molecular polymers, synthetic oligomers and some organic substances with relatively small molecular weight, such as C60 or C60 grafts. Wait. The sample to be tested may be single component or multi-component, but the more sample components, the more complex the spectrum and the more difficult the spectrum analysis; if there is mutual inhibition between components during ionization The effect does not necessarily guarantee that each component will peak. The amount of sample conventionally measured is about 1 to 10 picomoles per microliter.

(2) Solubility of the sample

The sample to be tested must be soluble in a suitable solvent, preferably an undissolved solid or a pure liquid. If the sample is a solution, information such as the solvent, concentration or content of the sample should be provided.

(3) Purity

For high quality mass spectra, peptide and protein samples should be protected from sodium chloride, calcium chloride, potassium hydrogen phosphate, trinitrotoluene, dimethyl sulfoxide, urea, glycerol, Tween, sodium lauryl sulfate. Wait. If the sample to be tested cannot avoid the above reagents during the pretreatment, the sample must be purified by dialysis and high performance liquid chromatography. Water, ammonium bicarbonate, ammonium acetate, ammonium formate, acetonitrile, trifluoroacetic acid, and the like are all suitable reagents for purifying the sample. After purification of the protein sample, it should be lyophilized as much as possible. The salt in the sample can be removed by ion exchange.

7. UV-visible absorption spectrometer

(1) The concentration of the sample solution must be appropriate and must be clear and transparent, without the presence of bubbles or suspended matter;

(2) The amount of solid sample is >0.2 g, and the amount of liquid sample is >2 mL;

8. Gas Chromatograph

Samples that can be directly analyzed should be volatile and thermally stable. The boiling point is generally not more than 300 ° C. If it cannot be directly injected, it needs to be pretreated.

9. Liquid chromatograph

To dry the sample, it is best to provide the structure of the component to be tested; for complex samples, provide as much of the other components as possible in the sample.

10. Elemental Analyzer

(1) Fill in the elemental analysis sample registration form and provide the theoretical content of the formula and elements or other relevant information as much as possible;

(2) The sample must be a uniform solid particle or liquid containing no adsorbed water and purified. For example, the sample is impure (including adsorbed water, organic solvent, inorganic salt or other impurities), which will affect the analysis result and make the test value and calculation. Value does not match;

(3) The sample should be of sufficient quantity to meet the linearity and sensitivity of the method and instrument.

11. Ion chromatograph

The sample to be tested may be dissolved in water, or dilute acid or dilute alkali, and the acid or base used may not contain the ions to be tested. For compounds containing the element to be tested in the sample but present in a non-ionic state in water, acid or alkali solution, the corresponding sample preparation is required.

12. Plasma atomic emission spectrometer

(1) Requirements for samples to be tested (test conditions):

1 Please inform the source, type, and properties (eg, ore, alloy, silicate, special solid solution, high polymer, etc.). List the main ingredients, impurity components and their (estimated) content as much as possible; what is the lowest (estimated) content of the elements to be tested? For the solution, please specify the medium composition (solvent, type of acid and base and its (estimated) content) , fluorine (F-) or not? Because fluorine (F-) will seriously corrode the atomizer!

2 The solid sample is prepared into a solution containing no organic matter, and the final acidity is controlled to be 1 mol, and the sample amount is 5 to 50 mL.

If it contains suspended solids or sediment, be sure to filter it; please also send the reagent blank solution at the same time to deduct the blank.

3 samples are required to be processed into a solution before being sent to the test center.

(2) Due to conditions, the following elements and certain substances cannot be analyzed:

1 The sample is heated and dissolved when acid is dissolved (for example, B, Hg, S-2, Se and Si when dissolved with hydrofluoric acid (HF));

2 ceramics, glass and other inorganic acid can not be dissolved, only alkali fusion;

3 silicone, silicone rubber, plastic products, fibers or any ashing within 500 ° C, followed by acid digestion:

A. Volatile loss;

B. Those who cannot be ashed or insoluble (eg, B, Bi, Ge, Hg, Os, Ru, Sb, Se, Sn, Tl and Si when dissolved with hydrofluoric acid (HF); special solid solution, Polymers, etc.)

13. Atomic Fluorescence Spectrometer

(1) General requirements for sample analysis:

The objects analyzed by atomic fluorescence spectrometry are arsenic (As), selenium (Se), germanium (Ge), tellurium (Te), etc. and mercury (Hg) atoms in the ionic state. The sample must be an aqueous solution or soluble in acid.

(2) Solid sample:

1 Inorganic solid sample: The sample is properly dissolved to maintain proper acidity.

Detection of arsenic (As), selenium (Se), strontium (Te), mercury (Hg), the medium is hydrochloric acid (5%, v / v);

Detecting germanium (Ge), the medium is sulfuric acid (5%, v/v);

Mercury (Hg) is detected, the medium can also be nitric acid (5%, v/v), and the detection (As) medium can also be sulfuric acid (2%, v/v). 2ml crimp neck vials

Since copper, silver, gold, platinum and other metals interfere with the elements to be tested, arsenic, selenium, tellurium and mercury in the alloy samples should not be measured by the instrument.

2 organic or biological solid samples

The sample was nitrated to a solution and maintained at the proper acidity, and the acidity of the medium was the same as that of the inorganic sample.

(3) Limit requirements of the elements to be tested in the sample

Determined by the sensitivity and analysis method of the instrument, the upper and lower limits of the sample containing the test element are 0.05μg/g~500μg/g. Samples not in this range will not be able to guarantee the accuracy and reliability of the test results.

(4) Sample size

For each element detected, the solid sample amount is required to be not less than 2 g, the liquid sample amount is not less than 20 mL, and the water sample is not less than 100 mL.

(5) Other

14. Differential scanning calorimeter

Solid samples do not decompose or sublime over the temperature range tested, nor are volatiles produced. Sample size: a single test of inorganic or organic materials of not less than 20mg, the drug is not less than 5mg. Please indicate the test conditions (including: detection temperature range, rising and cooling rate, constant temperature time, etc.) when delivering samples.

15. Thermogravimetric Analyzer

Sample amount: not less than 30 mg. Please indicate the detection temperature range, experimental atmosphere (air, N2 or Ar), heating rate, gas flow rate (if special requirements are required).

16. X-ray powder diffractometer

The sample to be inspected may be in the form of a powder, a block, a film, and the like. The powder sample requirement is about 0.2g (depending on its density and diffraction ability); the bulk sample is required to have an approximate plane with an area of ??less than 45px × 45px; the film sample requires a certain thickness, the area is less than 45px × 45px; other samples Consult the laboratory.

17.X-shot single crystal diffractometer

The sample to be inspected must be a single crystal. When selecting a crystal, pay attention to the smoothness, color and transparency of the selected crystal surface. No small crystals are attached, and there are no defects such as defect overlap, cleavage damage, and cracks. The length, width and height of the crystal are all 0.1~0.4mm, that is, the diagonal length of the crystal is not more than 0.5mm (large crystals can be sampled by cutting method, and small crystals should be considered for diffraction ability).

18. Transmission electron microscope

Due to the high voltage limit of the electron microscope, the transmitted electron beam can only penetrate thin samples with a thickness of several tens of nanometers or less. Except for the fine-grained sample, which can be directly sampled by the medium dispersion method, the preparation methods of other samples mainly include physical thinning (ion and double spray thinning, etc.) and ultra-thin sectioning. In general, the sample preparation process that requires the physical thinning method must be completed by the user himself (the department that does not have the conditions for the sample preparation can rent the relevant equipment of the room). 2ml crimp neck vials

The preparation of ultra-thin slice samples requires complicated processes such as pre-treatment, embedding, and slicing, and the cycle is long (about one week). Because the instrument is a high-resolution electron microscope, in order to ensure the performance of the instrument and to play its high-resolution image observation characteristics, it is currently mainly accepted in the field of materials.

Field emission scanning electron microscope

The sample to be inspected must be dry solid, block, flake, fibrous or powder. It should have certain chemical and physical stability, and will not volatilize or deform under vacuum and electron beam bombardment; it is non-magnetic, radioactive and corrosive. Sample preparation of biological soft tissue containing more water requires the user to carry out the fixation, washing, dehydration and replacement with isoamyl acetate before the critical point drying. Finally, the chamber is subjected to critical point drying treatment.

The image sample should be pre-sprayed with gold film. Under normal circumstances, the sample should be as small as possible (≤10x10x5mm is more convenient). The powder sample needs about 1 gram each. Nano-samples generally require ultrasonic dispersion and spray ultra-fine gold films.

20. Scanning electron microscope - X-ray energy spectrometer

The sample to be inspected must be a dry solid, in the form of a block, a sheet, a fiber, a granule or a powder. It should have certain chemical and physical stability, and will not volatilize or deform under vacuum and electron beam bombardment; it is non-magnetic, radioactive and corrosive. For biological soft tissue samples with a large amount of water, the user is required to perform fixation, washing, dehydration, and replacement with isoamyl acetate before the critical point drying.

Finally, the chamber is subjected to critical point drying treatment. The image observation sample should be pre-gold plated, and the component analysis sample must be coated with carbon film. Under normal circumstances, the sample volume should not be too large (≤ 5x5x2mm is more suitable).

21. Electron probe 2ml crimp neck vials

Samples for quantitative analysis must be smoothed and cleaned. If the sample can not be surface smoothed and polished (which will affect the analysis accuracy), it should be explained in advance. For the convenience of testing and saving the machine, the sample should be cut into small pieces first, and the sample cannot be cut. It must be discussed with the tester first.

The test points on the analysis surface should be marked first. When the test position is not marked, only the representative and flat position test is selected during the test. The liquid sample must be concentrated and dried first. The sample to be analyzed must be a solid with stable physical and chemical properties under high-energy electron bombardment, no decomposition, no explosion, no volatilization, no radioactivity, no magnetism. It is best to indicate what elements the sample may contain when delivering samples. The sample must be sprayed with a carbon film. 2ml crimp neck vials

This is the end of the introduction of Requirements for samples sent by laboratory analytical instruments. I hope it can help you.


Send Inquiry Live Chat Back To Top