Most of the sample vials are made of glass, in addition to glass, there are other materials such as polypropylene、polymethylpentene. Classification of laboratory glass is based on its water resistance USP( American pharmacopoeia).In general, USP Types II, III, and NP sodium calcium glass, chemical tolerance are not as good as borosilicate glass.
Polypropylene (also called as PP) is a hard material that can be processed into multiple colors and has good chemical tolerance and is suitable for short-term storage of most laboratory chemicals. When aromatic or halogenated hydrocarbons are used, their tolerance decreases with time. Because of the low ion content and can be cleaned with dilute acid and deionized water, PP sample vials are often used in ion chromatography. Because sealed can be directly incinerated, so PP sample vials also reduce the exposure of harmful substances.
Polymethylpentene (known as TPX) is a hard, transparent material, provided with a high melting point and a range of 0°-170°C. Because of its high transparency, TPX sample vials can replace opaque PP. Its chemical tolerance is similar to that of PP, TPX sample vials are usually used where visual samples or high temperature use is required. TPX sample vials are brittle at room temperature.
There is no exact concentration, which is determined by a variety of factors. The minimum injection concentration is generally determined by the minimum detection limit or the quantitation limit. The method for detecting the content needs to determine the quantification limit. The item for the purpose of impurity inspection needs to determine the detection limit. This limit concentration is the effective minimum injection concentration.
The highest concentration is generally verified by measuring 120% ~ 200% of the limit concentration. For example, when the sample concentration is determined to be 1mg / ml, the highest concentration can be verified to 1.2mg / ml; for example, the concentration of the sample vial impurity A control solution If it is 1μg / ml, the highest concentration can be verified to 2μg / ml.
The maximum / minimum concentration of sample vial injection is related to the following factors: 1. The detection capability of the detector. The detection capabilities of detectors such as ultraviolet, evaporative light, differential, and fluorescence vary. Among them, the sensitivity of the UV detector, the energy of the light source, the permeability of the flow cell, and the degree of cleanliness will all determine the detection capability of the UV detector. 2. The response value of the substance. The signals detected by different substances under the same detector have different sizes, which are also at a concentration of 1 mg/ml. The response values of substance A and substance B may differ by as much as 2, 10, or even 100 times. 3. Ultraviolet detection wavelength. The response value of the same substance at different ultraviolet wavelengths is different, which is related to the absorption value of the substance at that wavelength. 4. Chromatography column. Sometimes the concentration of the substance is too high to exceed the loading range of the column, which will cause the substance to form “flat peak” or peak bifurcation, shoulder peak, poor symmetry, and other separation problems, affecting the highest concentration. Some chromatographic columns will adsorb substances, and the effect may be very small when the amount is high, but at very low concentrations, the minimum detection limit that can be achieved by different sample vials may be different. 5. Verification by methodology. The concentration range actually applied to the formal inspection method should actually prove the rationality and feasibility of the concentration through a series of methodological verifications. In the methodological verification, the scope of the method should be verified by linear test, recovery test, repeatability test, specificity test, system suitability test, and a series of durability tests within the concentration range.