How To Buy Different Classifications Of Vacuum Filtration System

The microbiological detection multi-linked vacuum filtration system is suitable for food and beverage production enterprises, pharmaceutical factories, disease control centers, medical treatment, university scientific research, or third-party testing institutions. It is suitable for the detection and filtration of the microbiological limit of the water to be tested. The principle is to install a filter membrane at a specific position in the filter device, pour the sample, and use the pressure difference generated by the vacuum pump to make the liquid pass through the filter membrane. After filtering, the filter membrane is placed in a Petri dish for cultivation.

The obvious difference from the general filtration is that the number of inspection samples is large. The use of traditional single-type filter bottles may result in lower filtration efficiency, and the use of professional microbiological detection multi-unit vacuum filtration system can filter out 3 groups at a time, 6 groups or more samples. At the same time, due to special use requirements, the requirements of microbiological testing for sterility and pollution avoidance are even higher.

There are many types of microbiological detection multi-vacuum filtration systems on the market. Customers can choose products that suit them according to these items when choosing:

The number of filtered samples: the common model classification is generally based on single, triple, and six. The main difference is the number of samples that the user can filter at a time, corresponding to 1, 3, and 6 groups, respectively. The unit needs to be filtered sample size to choose from.

At present, it is recommended that customers use the triple water microbial inspection vacuum filtration system. A vacuum suction pump is equipped with a set of triple filter brackets with three filter cups on the bracket, which can be filtered at the same time or can be closed using the valve switch lowered by the filter cup. No need for filter cups. And its big feature is that when the customer needs to increase the number of filtered samples in the future and need to expand the filter seat, only need to buy one more triple seat, through a straight connector can connect two triple seats in series, and still use only the original configuration a suction filter pump can realize the filtration work, no need to purchase additional suction filter pump.

Filter material: The filter material part can be divided into two parts, the main bracket material, and the funnel material. At present, the materials of the mainstream products are stainless steel and aluminum alloy. Both the aluminum alloy and the stainless steel can be sterilized at 121 degrees high temperature and high pressure, while the aluminum alloy has the advantages of lightweight.

The material of the stainless steel series vacuum filter body adopts cash anode aluminum alloy; funnel material types are more divided into stainless steel, glass, plastic, ceramic, etc., among which stainless steel material can be directly burned and sterilized by flame, the price of glass material is cheap, the structure of plastic material is simple and lightweight, and it is currently used. More and more widely.

How To Buy Different Classifications Of Vacuum Filtration System

Detailed Description Of Sample Vial And Material

Linear expansion coefficient refers to the length of the glass changes with each degree change in temperature. The lower the linear expansion coefficient is, the greater the temperature change the glass can bear. The classification of laboratory glass is developed by USP (United States pharmacopoeia) according to its water resistance.

[USP TYPE 1, grade A, 33 borosilicate hydrochloride glass] The most chemically inert glass is widely used in laboratories, especially for chromatographic analysis. Grade I glass is mainly composed of silicon and oxygen, containing trace amounts of boron and sodium, with the lowest solubility and linear expansion coefficient of 33.

[USP TYPE 1, class B, 51 borosilicate hydrochloride glass] It consists mainly of silicon and oxygen, contains trace amounts of boron, sodium, and more alkali metals than grade A glass, but is still suitable for laboratory use. All brown glass is grade B glass with A linear expansion coefficient of 51.

Silanized or deactivated glass
Borosilicate hydrochloric acid glass, which has been deactivated by organosilicon, has a highly hydrophobic and inert glass surface and is suitable for ph-sensitive compounds, trace analysis, and long-term sample storage.

[sample vial with screw orifice] Provides bottom evaporation, reusable, hurt less than pliers flap competitors sealing way, without additional tools, thread cover sample vial in different specifications to distinguish, the specification defined by glass packaging association (GPI), thread samples of bottle mouth, such as 9-425 sample bottleneck is about 9 mm thread diameter, thread type for 425, thread sample vial mouth and the cover pad is higher than jaw vial price.

[screw head sample vial cap pad] There is an open hole cover designed for automatic sample injection, a solid cover designed for sample storage, and an optional integrated PP cover. This piercable threaded cover is designed for a single sample injection and does not require cover pad assembly, which can save time for experiment preparation.

[sample vial with clamp] Seal with aluminum cover, relatively cheap, when properly clamped, can be used for long storage to provide the best seal, clamps can not be reused, requires a greater force clamped.

[bayonet sample vial] Seal with gland holder and remove gland holder from lid opener. It can be used together with a bayonet cap or bayonet cap. No tool is needed when using the bayonet cap. As its sealing property is not as good as that of a screw vial with clamps, it is recommended for short-time sample storage or non-volatile samples.

Detailed Description Of Sample Vial And Material

A Brief Introduction To The Extraction Thimble

Extraction thimble is an instrument for extracting nonvolatile substances from solids with a volatile solvent. It consists of three parts: reflux condenser, extractor body (with filter paper sleeve), and flask for solvent. The extracted sample is placed in a filter tube, and the solvent is heated. The steam rises from the side tube and drops into the sample through the reflux condensate tube. In this way, a relatively small amount of solvent can be used to achieve the purpose of complete extraction. Often used for fat extraction.

Use
One method of extracting compounds from solid substances is to leach the desired substances by soaking the solids in a solvent for a long period of time. The solvent dosage is large, the efficiency is not high. The extractor used in the laboratory is to use the principle of solvent reflux and siphon so that the solid material is continuously extracted by pure solvent, which not only saves solvent but also increases extraction efficiency.

The solids are ground up before extraction to increase the area of solid-liquid contact. Then the solid substance is placed in the filter paper cover and placed in the extractor. The extractor is connected to a round bottom flask with a solvent at the bottom spoon and connected to a reflux condenser tube. Heat the flask, the solvent boiling, steam rising through the extractor pipeline, after condensation drops into the extractor solvent for extraction, and solid contact when four of the top solvent than the siphon, contains extract solvent siphoned back into the flask, and therefore part extracted substances, repeat, the solid material continuously to pure by solvent extraction, extracted substance concentration in a flask.

Liquid – solid extraction is the use of a solvent mixture of solid solubility of the ingredients in big, less solubility of the impurity to achieve the purpose of the extraction and separation. One way is to put the solid material in the solvent medium and long-term immersion and reach the purpose of extraction, but this method a long time, consumption of solvent, the extraction efficiency is not high also. Another is the method of soxhlet extractor, it is using the solvent backflow and siphon principle, for continuous extraction of solid mixture components needed.

When the extraction tube under the reflux solvent in the liquid level exceeds the siphon of the soxhlet extractor, extraction solvent flow in the tube back to the round bottom flask, namely siphon. With the temperature increases, at the beginning of reflux again, before each siphon, the solid substance can be extracted by the pure hot solvent, the solvent is repeatedly used to shorten the extraction time, so the extraction efficiency is higher.

Extraction – a method of separating solute from the solvent by extracting a substance from one solvent into another, taking advantage of its different solubility in two incompatible solvents. In fact, extraction is the motion of molecules or atoms, which is the result of atoms or molecules interacting with each other.

For example, bromine, which is more soluble in carbon tetrachloride than in water, we now want to separate bromine from water by adding bromine water to the divider, adding an appropriate amount of carbon tetrachloride, fully oscillating, standing, waiting for the mixture to stratification, you can see that the majority of bromine dissolved in carbon tetrachloride. We let the lower carbon tetrachloride flow out below, and the water flows out above, and that separates the bromine from the bromine water.

As for the effect of extraction, it mainly depends on the choice of extracted substances and extractants:
The extracted substance has a greater solubility in the extractant. The extraction agent and the original solvent do not dissolve. The extractant does not react with the extracted substance. The extractant is usually an organic solvent.

A Brief Introduction To The Extraction Thimble

310rpm Water Bath, LCD Display Standard Rotary Evaporator

RE1-W-L series-standard rotary evaporator is a water bath rotary evaporator specially developed for the needs of laboratory customers. With beautiful appearance design and suitable size, 5 Liter rotovap can be operated quickly.

Rotary vacuum evaporator price 

concessions, which are suitable for schools, laboratories, research institutes, and other experiments that need companies.

Hawach provides a

 

2L/3L/5L rotary evaporator

 

with either A or B type connection.

Features of RE1-W-L series-standard 2L & 3L & 5L rotary evaporator.

1. The temperature of the RE1-W-L series-standard rotary evaporator can reach as high as 99°C for water bath experiments. The heater will stop automatically when the temperature arrives at the set figure. Rotary vacuum evaporator price is the most economic for high-speed 310rmp/min water bath.
2. Rotary speed can be adjusted by an electronic step-less speed regulation system. Rotary speed for 

2-liter rotovap and 3L rotary evaporator can be set to 310rpm/min. But that for 5-liter rotovap can only reach as high as 200rmp/min.

3.  Apart from the large double flux condensation area, there is a drop point under the condenser and also with backflow prevention design to maximize the distillation process of a 5L rotary evaporator.
4. The integral Teflon bath is equipped with a totally enclosed heating tube, which is safe and reliable.
5. This series rotary vacuum evaporator price in Hawach products is the most cost-effective.
6. It is equipped with a vacuum gauge to observe the internal vacuum at any time. When the vacuum degree reaches the bottom, we can turn off the vacuum valve to keep the vacuum degree, decrease the noise and prolong the service life of the vacuum pump.

310rpm Water Bath, LCD Display Standard Rotary Evaporator

Triple-Stage Stainless Steel Molecular Distillation

1. Overview of molecular distillation

Wiped film vacuum distillation

 

is a special liquid separation equipment, which is different from traditional distillation such as rotary evaporator and reactors,

 

stainless steel short path distillation

 

has its unique separation principle, it relies on the different average free path of molecular movement rather than the different boiling point.

Short path wiped film distillation kit

 

has its special advantages which with high distillation efficiency and low temperature physical distillation property.

 

triple-stage stainles steel molecular distillation

 

technology is widely used in distillation, purification, solvent removing, decoloration, and deodorization of many substances, especially the heat-sensitive substance.

2. Features of molecular distillation
(1). The operating temperature of the short path molecular distillation kit is far below the boiling point of the material, and the residence time of the material is really short, which is beneficial to separate materials with the high boiling point, heat sensitive and easy oxidized.
(2). The stainless steel short path distillation can effectively remove substances in liquids such as organic solvents, odors, etc, which is a very effective method for liquid desolventizing after solvent extraction.
(3). The vacuum degree of the wiped film vacuum distillation can reach below 0.1Pa ensures the material not to be oxidized easily during distillation.
(4). The triple-stage stainless steel molecular distillation can form a liquid film less than 0.5mm, which make sure that distillation with high efficiency of heat transfer.
(5). Stainless steel short path distillation with a high degree of separation can be used to separate by conventional substances that are not easily be separated.
(6). Using short path molecular distillation kit there is no boiling or bubbling phenomenon.
(7). The wiped film vacuum distillation is a physical separation method, toxic-free harmless, pollution-free and no residue, which confirms to obtain pure and safe products.
(8). The surface of the stainless steel short path distillation was contacting with materials is made of 316L stainless steel, and the exterior surfaces of the stainless steel short path distillation are made of 304 stainless steel. Which ensures the overall thermal expansion performance and thermal insulation performance of the stainless steel wiped film molecular distillation are really good.
3. Why triple-stage stainless steel molecular distillation is needed?

Stainless steel short path distillation is a distillation method operated in a high vacuum state. This method of separating liquid mixtures by using the different free path of the molecular movement of each component in the liquid material, this wiped film vacuum distillation is widely used in food, medicine, fine chemical, and other industries applications.

However, single-stage short path molecular distillation kit also has certain defects. Because single-stage stainless steel short path distillation equipment has only one heating surface and one condensation surface, for liquid materials composed by multiple mixtures entering to the wiped film vacuum distillation, there is only once distillation in the single-stage short path molecular distillation kit, which can remove most of the lightweight molecular fractions in multiple mixed liquids, and a small portion of the lightweight molecular fractions are still present in the multiple mixed liquids, due to the mixed liquid its own characteristics or the thinness of the liquid film can not be distilled sufficiently in the single-stage stainless steel short path distillation.

If there are multiple substances need to be distilled in multiple mixed liquids by single-stage short path molecular distillation kit, then the single-stage wiped film vacuum distillation must be used again and again by adding the previous distillation product to the single-stage stainless steel short path distillation equipment and reset the distillation temperature every time.

In this way not only has complicated operation and high cost, but also the product after previous distill by the wiped film vacuum distillation equipment cannot guarantee the quality and purity, due to the influence of temperature, liquid film thickness, distillation time and other factors. Therefore, the production of a multi-stage short path molecular distillation kit is very meaningful. Then the triple-stage stainless steel molecular distillation not only can get the different components from the mixed liquids at one time but also the distillation quality and purity can be improved, which can largely avoid repeated operations, labor loss and material loss.

Triple-Stage Stainless Steel Molecular Distillation

Always Ready For Your Filtration, With the Magic of Vacuum Filtration

The scientists are doing filtering in the lab almost every day. It is difficult to imagine how we can achieve effective separation without filtration tools, such as vacuum filtration, which is an essential part of many purification systems.

Before you take the vacuum filtration into practice, you should pay attention to some considerations.

First, make sure that the glass you are going to use in your vacuum filtration can stand the pressure of vacuum filtering. For this reason, the borosilicate of high-quality glass is always recommended.

Second, the filter paper is the main factor that reduces the flow rate at a different speed. That’s why we use vacuum filtration to increase the flow rate and save time. On the other hand, if the vacuum is too strong, it will damage the filter paper.

Third, you can discard, reuse, or process the residue which is left on the filter paper again, depending on what you are filtering. The filter can also catch other solid particulates, such as catalysts, salts, impurities.

Hawach is always ready to provide a wide selection of essential vacuum filtration equipment and supplies for the labs all around the world, large and small. Now, we will introduction Hawach diaphragm vacuum pumps for you from the application area, operation, and performance optimization.

Application Area of Diaphragm Vacuum Pumps

Diaphragm vacuum pump provides advanced design, high working efficiency, and long service life, which is a replacement product with high and new technology. It is mainly used in the fields of medical and pharmaceutical product analysis, filtration of pharmaceutical products analysis, fine chemical industry, biochemical pharmaceutical industry, food inspection, and so on. It is a matching product for its precision chromatographic instrument and one of the necessary equipment in the laboratory. It is light and portable, and it has a wide range of applications and high corrosion resistance, so it can meet the requirements of all kinds of working environments.

Operation of Diaphragm Vacuum Pumps
Hawach diaphragm vacuum pumps adopt novel technology and materials in the production process. It uses frictionless film body motion, and thus produces no heat and no friction loss. A self-cooling exhaust system is designed to ensure continuous operation 24 hours. The pressure adjustable design can greatly meet the vacuum degree and gas flow rate in a certain range. The bearings adopt imported classic bearings, which directly guarantee smooth operation, low noise, and high working efficiency.

Performance Optimization of Diaphragm Vacuum Pumps

1. Diaphragm vacuum pump shall be installed in a clean and ventilated place, and there shall be sufficient room around it for easy inspection, maintenance and maintenance.
2. In the connection line, the user can install the valve and vacuum gauge above the inlet of the diaphragm vacuum pump, and check the limit pressure of the diaphragm vacuum pump at any time.
3. The internal components and wetted parts of diaphragm vacuum pumps are all PTFE-coated for good corrosion resistance and electricity leakage, so there is no need to install additional leak-proof equipment.
4. The vacuum booster and backing pump are all connected on a compact base frame, which makes the ingress of fluids and particles become impossible, and thereby avoiding corrosion and human intervention.
5. The diaphragm vacuum pump is equipped with high-efficiency motors, which offer good energy efficiency and higher pumping speeds, and there is no need for setting the standard in the performance class.
6. Fit-in-place design retrofits the diaphragm vacuum pump to existing systems, optimizes the operation process, and reduces the maintenance requirements.

Always Ready For Your Filtration, With the Magic of Vacuum Filtration

HAWACH To Let You Know The QuEChERS Method Comprehensively

To discuss the disadvantages or advantages of QuEChERS, you need to compare it with other technologies. We believe that the advantages of QuEChERS are obtained by comparing with other methods in many laboratories, and its shortcomings are more from personal preferences. The so-called shortcomings are not from their inherent defects. QuEChERS has undoubtedly changed the method of sample processing in pesticide residue analysis. Even those laboratories that do not use QuEChERS will use centrifuge tube extraction or dispersion matrix extraction in their methods.

Detection limit
There is another issue of note. Before the emergence of QuEChERS, the extraction solution obtained by the pesticide residue detection method generally contains 2-5g of sample per milliliter of non-polar solvent. At this time, when GC / MS (SIM mode) is used for splitless injection, the injection volume is 1 to 3 µL, and the method detection limit is generally 10 ng/g. Now unless the tester concentrates the extraction solution again, or perhaps replaces the solvent, the general QuEChERS method produces the extraction solution in acetonitrile, which is equivalent to the only 1g of sample per ml. In order to enable it to reach the detection limit of the previous method, programmable temperature vaporization (PTV) combined with large-volume injection (LVI) of 3 to 10 µL is required.

The high cost of acetonitrile
In addition, acetonitrile is a good solvent for liquid-phase methods, but completely different for gas-phase. The use of PTV-LVI can reduce the amount of solvent entering the gas chromatography column. Therefore, if the appropriate method can be used, the use of acetonitrile will not be a disadvantage for the gas phase, but acidification of acetonitrile requires care-there are some sensitive pesticide residues will degrade in acetonitrile (perhaps at least in some batches of solvents), for which we can improve the stability of such pesticide residues by acidifying acetonitrile, but there are reports showing that it can increase column loss. Acetonitrile is more expensive than other solvents, but the QuEChERS method requires only 10 to 15 ml of acetonitrile per sample.

Chlorophyll interference
Chlorophyll interference may be a potential disadvantage because even if 7.5mg GCB or 50mg ChloroFiltr adsorbent is added to each milliliter of extract, the removal rate is only 80 to 90%. For the removal of such macromolecular impurities, gel chromatography GPC has a better extraction effect than the dispersion matrix, but GPC has obvious disadvantages in terms of time, instrument cost, and reagent usage. Moreover, in the removal of fat macromolecules, the dispersion matrix extraction using C18 filler may be comparable to GPC in the freezing effect.

Liquid phase analysis
The biggest problem mainly comes from liquid phase analysis. When the ionization method is API, the ionization of the analyte will be suppressed by the impurities flowing out at the same time. Most foods do not have this problem when using QuEChERS for sample processing; but for other more complex samples, we do not know whether QuEChERS will be more suitable than other methods. Current mass spectrometry has greatly improved sensitivity, and better ion source design can minimize the occurrence of such problems, but the competition between charges during ionization is an inherent characteristic of API, which is inevitable. The isotope internal standard is not suitable for all analytes, so the inspector has to evaluate the matrix effect, and the quantitative results of LC-API-MS can only be treated with caution before finding a solution.

HAWACH To Let You Know The QuEChERS Method Comprehensively

Volume Of The Sample Vial

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.

Volume Of The Sample Vial

Superior Silica Gel Flash Column And Protect The Flash Column

Excellent Separation and Purification Performance
Superior silica gel flash column adopts high capacity silica gel for accurate filling, which gives it very excellent separation and purification performance. The surface area of high capacity spherical silica gel is 40% higher than that of ordinary spherical silica gel, and the sample size is twice that of ordinary spherical silica gel. Meanwhile, the surface area is 40% higher than normal spherical silica gel; a higher sample size means smaller, faster, and more economical chromatographic columns used for separation; less solvent use, and higher separation.

Good Reproducibility and Medical Grade Materials
Superior silica gel flash column is automatically filled with proprietary technology, the column bed is tight and uniform, and there is no “ditch flow effect “. Positive and inverse silica gel fillers with different particle sizes allow users to freely select different fast separation columns in terms of separation degree, sample size, and flow rate according to different economic and efficiency requirements. The rapid separation column is made of medical-grade polypropylene material, which avoids the dissolution contamination of separated samples by ordinary PP materials. Additionally, transparent PP material cylinders allow users to visually observe sample separation.

How to protect the column

The key to maintaining long column life is proper sample handling before injection. You must prevent pumping compounds that are very hydrophobic/different from the polarity of the mobile phase into the column, whether from the mobile phase or the sample. In particular, the introduction of particulate impurities should be prohibited.  These will eventually increase the operating pressure and is very difficult or impossible to remove.

Be sure to use a guard column, because contamination of the sample and eluent may cause an increase in column pressure and affect selectivity. For Hawach columns, we recommend using the correct type of guard column. The packing material of this column is similar to that of the chromatography column used for analysis. The guard column needs to be replaced when the column pressure increases or the column efficiency is observed to decrease.

Attention during storage:

Do not store the column in a column filled with buffer or other salt-containing eluents. Storage solvents should contain at least 20% organic solvents to prevent the growth of bacteria.

Possible causes of loss of column efficiency:

Extra peak broadening. When using columns with small diameters or short lengths, peak broadening may be more apparent. To ensure that the length and the inner diameter of the pipeline is kept small. Check the injection volume and detector to check whether the cell volume is suitable for the column volume.

The equilibration time for elution is not enough.
Incorrect column temperature.
Incorrect correction density.

An excessive elution flow rate was used. Reverse the column and use a low flow rate.

Superior Silica Gel Flash Column And Protect The Flash Column

About The HPLC Main Components And Its Column Maintenance And Use Notes

HPLC has been widely used in many fields such as food additives and pharmaceutical composition analysis due to its advantages of accurate quantitative analysis results, short analysis period, wide analysis range, and low detection limit.

Introduction of main components
Infusion system
The infusion system mainly includes an online degassing device, a high-pressure infusion pump, and a gradient elution device. The main function of the online degasser is to remove bubbles before the mobile phase enters the column. The packing particles of the liquid chromatography column are small, and the flow resistance through the 2 ~ 5 mm column is very large. Therefore, the mobile phase needs to be extracted by the high-pressure infusion pump and sent to the column.

High-pressure pumps can be divided into constant pressure and constant flow pumps according to infusion performance. Based on the mechanical structure, it can be divided into a hydraulic diaphragm pump, pneumatic amplification pump, screw injection pump, and reciprocating plunger pump.

Sampler
The sampler is a device that sends analytical samples to HPLC chromatographic column. It is divided into manual and automatic injectors. The manual sampler is generally equipped with a 20-100 μL quantitative loop.

HPLC chromatography column
The column uses liquid as the mobile phase and the solid phase in the broad sense as the stationary phase to separate the analytical samples. Chromatography columns can be roughly divided into normal-phase chromatography columns and reverse-phase chromatography columns according to the separation mode.

Detector
The detector converts the physical or chemical characteristics of the sample separated by the chromatographic column into measurable electrical signals, records them through the chromatogram, determines the separation effect from the peak shape in the chromatogram, and performs qualitative and quantitative analysis on the sample according to the peak time and peak area of the chromatogram of the standard and analytical sample.

HPLC column maintenance and use notes
Adjust the pH value of all the analyzed samples to the pH range suitable for the column. Avoiding overloading during injection is one of the important methods to maintain long-lasting and good column performance. If the manual injector is used for injection, the action should be fast and accurate during the injection. When the analyte composition is complex, a chromatographic protection column should be added in front of the column to protect the column. At the beginning of each analytical work, the chromatographic column should be equilibrated. The aqueous solution containing 10% of the organic solvent in the mobile phase is used for exhausting and flushing the chromatographic column and pipeline. Replace, and then equilibrate the column with a mobile phase of at least 10 column volumes until the baseline is equilibrated before injecting.

After each analysis, the buffer salt solution in the HPLC chromatographic column must be thoroughly rinsed with a certain amount of aqueous solution, and then the column should be rinsed with a solvent that has a strong elution capacity for the test substance. The amount of desolvation is at least 20 times the column volume. If the chromatographic column is not rinsed in time, impurities will accumulate in it for a long time, which will easily block the chromatographic column and reduce the efficiency of the column. In the long run, this will accelerate the reduction of column life. If the chromatographic column is not used for more than 4 days, it should be removed from the instrument and sealed tightly with a head nut. When storing the column, be careful not to vibrate or collide it strongly.

About The HPLC Main Components And Its Column Maintenance And Use Notes

The Specific Use Method Of SPE Cartridge

1. Select the SPE cartridge or filter membrane.

Firstly, according to the physical and chemical properties of the object to be measured, and the substrate of the sample, the fixed phase with strong retention ability should be selected. If the object to be tested has a negative charge, anion exchange packing can be used; otherwise, cation exchange packing can be used. If it is a neutral substance to be measured, it can be extracted with reverse phase packing. The size and specification of the SPE cartridge or membrane should depend on the concentration of the sample to be measured. For in vivo samples with low concentration, less fixed phase filler should be used to extract larger volume samples.

2. The activation
Before extraction, rinse the cartridge with a solvent filled with the cartridge or rinse the filter membrane with 5 ~ 10ml solvent. Generally, methanol and other water can be used first.
The soluble organic solvent rinses the filler because methanol wets the adsorbent surface and penetrates the non-polar silica gel bonding phase, making the silica gel easier.
Wet with water, then rinse with water or buffer. Before sample addition, SPE packing should be kept moist. If the packing is dry, the sample retention value will be reduced. However, the different drying degree of each cartridge will affect the reproducibility of the recovery rate.

3. On the sample
Generally, the following measures can be taken: (1) using 0.1mol/L acid or base regulation, pH<3 or pH>9. Centrifugal extraction of upper liquid;(2) the protein was precipitated with methanol, acetonitrile, etc., then the supernatant was taken and diluted with water or buffer solution for extraction;(3) the supernatant was taken after the protein was precipitated with acid or inorganic salt, and the pH value was adjusted for extraction;(4) after ultrasound for 15min, add water and buffer solution, and extract with supernatant. The drug concentration in the urine sample is relatively high. Before adding the sample, dilute with water or buffer solution. When necessary, acid and alkali hydrolysis reaction can be used to destroy the combination of drug and protein, and then extract. The flow rate should be controlled to 1ml/min, and the fast flow rate is not conducive to the combination of the object to be measured and fixation.

4. The elution
The cleaning solvent of reversed-phase SPE is mostly water or buffer solution. A small amount of organic solvent, inorganic salt, or pH value can be added into the cleaning solution. The cleaning fluid added to the cartridge should not exceed the volume of one cartridge, and the SPE filter membrane is 5 ~ 10ml.

5. Elute the object under test
5 ~ 10ml eluent with weak ionic strength but capable of washing the substance to be measured should be selected. If higher sensitivity is required, the eluent can be dried before the mobile phase recombined residue is injected. In vivo samples, after elution contains more water, can choose the freeze-drying method. The SPE filler with weak retention ability can be washed with small volume and weak eluent, and then the eluent can be analyzed by the HPLC cartridge with strong polarities, such as C18 SPE cartridge.

If the substance to be measured can be ionized, the pH value can be adjusted to inhibit the sample ionization, so as to enhance the retention of the substance to be measured in the reverse SPE filler. During elution, the pH value can be adjusted to ionize the substance and elute it with a weak solvent. After collecting the eluent, the pH value can be adjusted to achieve the best separation effect in the HPLC analysis. In the process of elution, the flow rate should be slowed down, two small volume elution instead of a large volume elution, the recovery rate is higher.

The Specific Use Method Of SPE Cartridge

Structure And Design Feature of Roll Type Filter Membrane

Instruction to Structure of Roll Type Filter Membrane
The filter membrane is divided into three types according to the structure of membrane: roll membrane, ceramic membrane, and hollow fiber membrane. Roll type membrane plays an important role in membrane filtration technology. Now let’s focus on a roll film. By the guide screen, membrane and membrane support materials stacked in turn, with the adhesive along the three sides of the two layers of membrane bond seal, the other open side and the middle through the liquid collecting pipe connection, and then winding together. The liquid containing the material flows from one end into the diversion barrier and from the other end, flowing through the liquid along with the porous supporting material and drawn from the intermediate collecting pipe.

Advantages of Roll Type Filter Membrane
Roll type filter membrane is characterized in the wide distribution of filter aperture, a large area of the single membrane, high filtering accuracy, and relatively low energy consumption. In application, it can withstand higher pressures. The operating temperature is generally not higher than 45℃, and the operating temperature of the special film reaches 80℃.

Configuration of Roll Type Filter Membrane
Hawach discloses a roll type filter membrane, the inner part of which is provided with a central filter tube, the outer side of the diaphragm layer is provided with a membrane shell, the two ends of the filter are provided with a raw water seal washer, the other end of the original water seal washer is provided with an outlet pipe, the surface of the original water seal washer is provided with an inlet and outlet water hole, the diaphragm layer includes an inlet water screen, the outer side of the inlet water screen is provided with a water production screen, and the outer side of the water production screen is provided with graphene nanometre.

The function of Roll Type Filter Membrane
The roll type filter membrane can greatly accelerate the water production speed by setting a ceramic central filter tube, and the graphene nano-film built into the diaphragm layer effectively improves the purification ability and water quality purification effect of the membrane layer. At the same time, the filter ends are buckled with raw water seal washer, which is convenient to disassemble, easy to clean up the fouling on the membrane surface, reduce the fouling plugging of the diaphragm layer, avoid the secondary pollution of the water source, and ensure our healthy life.

Adsorption Mechanism of Membrane Filter
According to the adsorption mechanism and the pore characteristics of the membrane layer and the supporting layer, it can be explained why the membrane filtration is easy to block the oily sewage for the clean water. For general solid suspended matter, particles larger than the membrane pore are intercepted (screened) on the surface of the membrane, and particles smaller than the membrane pore pass through the membrane pore, which cannot be adsorbed on these particles because of the thin film as the filter layer. Although the supporting layer is relatively thick, its pore is larger than the membrane pore and is not sufficient to produce adsorption.

Structure And Design Feature of Roll Type Filter Membrane

Several Points Should Be Considered In The Selection Of Filter Paper

Filter paper on the market can generally be divided into qualitative and quantitative. In the application of analytical chemistry, when inorganic compounds are separated by filtration to precipitate, the residue collected on the filter paper can be used to calculate the loss rate during the experiment. Qualitative filter paper produces more cotton fibers after filtration, which is an ideal choice for qualitative analysis; quantitative filter paper, especially ash-free filter paper, undergoes special processing procedures and can effectively resist chemical reactions, so the resulting impurities Less, can be used for quantitative analysis.

In addition to filter papers used in general laboratories, there are many applications of filter papers in daily life and engineering. Coffee filter paper is one of the widely used filter papers. The filter paper on the outer layer of tea bags provides high softness and high wet strength. Other air filter papers for testing suspended particles in the air, and fiber filter papers for different industrial applications.

The technical indicators of filter paper can be divided into two aspects, one is the filter characteristics of the filter paper, and the other is the physical characteristics. Filtration characteristics include air permeability, air resistance, maximum pore size, and average pore size. Physical properties include basis weight, thickness, stiffness, corrugation depth, burst resistance, resin content, etc.

Quantity: refers to the mass of filter paper per square meter, unit: g / m?
Thickness: refers to the thickness of the filter paper, excluding the corrugated depth. Unit: mm.
Air resistance: the resistance of filter paper to airflow. It is represented by the pressure drop value obtained by passing 100 liters of filter paper through 85 liters of air in one minute. The unit is mbar. Or the water column height (mm).
Corrugation depth: the depth of the groove pressed to strengthen the longitudinal stiffness of the filter paper, the unit is mm. In general, the value is 0.2mm.
Air permeability: the amount of air passing through the filter paper per unit time under a certain area and certain pressure (20 mm water column). The unit is L / m2 · s.
Nominal filtration accuracy: refers to the retention capacity of the filter paper to particles of a certain size, and the particle size of the tiny spheres when 50% can be retained or filtered out Unit: μm.
Maximum pore size: the void size calculated by the pressure when the first bubble emerges from the filter paper sample during the test. Unit: μm.
Average pore diameter: The pore diameter calculated by pressure when “dense” bubbling is called the average pore diameter. The unit is: μm.
Resin content: The percentage of resin in the weight of filter paper. Generally 10% ~ 30%.
Stiffness: the deformation resistance of filter paper. Unit: mg.
Burst: the maximum pressure that the filter paper can withstand per unit area. Unit: kPa.

1. The effective area is large, that is, the use area of the filter paper is large, the dust holding capacity is large, the resistance is small, the service life is long, and of course, the cost increases accordingly.
2. The finer the fiber diameter, the better the interception effect, and the correspondingly higher filtration efficiency.
3. The content of the binder in the filter material is high, the tensile strength of the paper is high, the filtration efficiency is high, the lint phenomenon is less, the dust background of the filter material is small, the resistance is good, but the resistance increases.

Several Points Should Be Considered In The Selection Of Filter Paper

Syringe Filters Increase Sensitivity And Accuracy Of Analysis Results

Brief introduction

Syringe filters can be found in the chromatographic analysis to filter mobile phases and samples. The presence of impurities in the sample and solvent will not only cause damage to the chromatographic instrument and column, but will also greatly affect the analysis results. Organic phase syringe filters have a good effect on protecting the column and the chromatographic system from contamination, and can improve the sensitivity and accuracy of the analysis results. It is widely used in pharmaceutical analysis, food testing, environmental monitoring, protein removal and sterility testing.

Components

The shell is made of polypropylene (PP) with excellent chemical stability, made of different colors, which is convenient for users to distinguish between products with different specifications and avoid confusion. The filter membrane adopts high-performance filter membrane with stable product quality and good reproducibility, which is an ideal choice for laboratory filtration samples. The standard interface is convenient to connect with various syringes, and it can also be directly connected to the syringe of the valve, which can be directly injected after filtering.

Membrane materials determine the effectiveness of the filtration, and Hawach always implements high quality standard and humanized services, different syringe filters are available according to customer demand. The consistency between the production filter batches is good, from the raw materials to the production process and to the incoming and outgoing warehouse delivery management, the whole process has strict quality control, to the greatest extent to ensure the quality and use value of the product. Commonly membranes of various specifications such as PES、PTFE、Nylon、MCE、GF、PVDF、CA are provided, and the pore size range from 0.1μm to 5μm, the diameter includes 4 mm、13mm、17mm、25mm、30mm、47mm etc.

Syringe filters made of PTFE membrane has excellent chemical resistance, high temperature resistance, strong acid resistance, strong alkali resistance, strong hydrophobicity. Besides, hydrophilic membrane and hydrophobic membrane are all provided to meet different liquid filtration requirements. Polyvinylidene fluoride membrane is hydrophobic, which is featured in low moisture absorption, easy constant weight, and oxidation resistance. It is also design of thread interface.

Main features

The pore size is relatively uniform, the porosity is high, there is no medium shedding, the texture is thin, the resistance is small, the filtration speed is fast, the adsorption is very small, the price is low, but it is not resistant to organic solutions and strong acid and alkali solutions.

Uses: The pharmaceutical industry needs autoclaved water injection to filter out particles during large infusion.

For sterilization of heat-sensitive drugs (biochemical preparations such as insulin ATP and coenzyme A), use a 0.45 micron filter (or 0.2)

Medicine and health, using the thin film method to test the C-AmP, C-GmP and bloodworm of human body fluids, the determination of E. coli groups in drinking water, surface water and well water, and the detection of industrial and mining dust 0.8-5.0 microns.

Syringe Filters Increase Sensitivity And Accuracy Of Analysis Results