Equilibration Regeneration And Maintenance Of HPLC Column

For a general reversed-phase HPLC column, it is washed and put into pure methanol (acetonitrile) or about 80% methanol (acetonitrile) water, and then both ends of the column are plugged tightly with plugs to avoid evaporation of the preservation solvent. There should be no special protection.

The maintenance of the liquid chromatographic column is divided into the balance of the chromatographic column, the regeneration of the chromatographic column, and finally the maintenance of the HPLC chromatographic column.

HPLC Column equilibration
The reversed-phase column is stored in acetonitrile/water after being tested by the factory. The new column should be flushed with 10-20 column volumes of methanol or acetonitrile. Please make sure that the mobile phase you use for analyzing the sample is miscible with acetonitrile/water. Spend enough time every day to equilibrate the column with the mobile phase, you will get the greatest “compensation” in dealing with the problem, and the life of your column will become longer!

Operation steps: Slowly increase the flow rate at the beginning of equilibrium, and equilibrate the HPLC chromatographic column with the mobile phase until a stable baseline is obtained (if the flow rate of buffer salt or ion pair reagent is low, it will take longer to equilibrate).

If the mobile phase used contains buffer salts, you should pay attention to the “transition” with pure water, that is, you must rinse with pure water for more than 30 minutes before starting the analysis every day, and then balance with the buffer salt mobile phase; after the analysis, you must rinse with pure water 30 After removing the buffer salt for more than minutes, rinse the column with methanol for 30 minutes to protect the column.

HPLC Column regeneration
Chromatographic columns that are used for a long time tend to decrease their efficiency (the number of theoretical plates on the column decreases). The chromatographic column can be regenerated, and a cheap pump should be used to regenerate the column in a qualified laboratory.

When regenerating the NH2-modified chromatographic column, since NH2 may exist in the form of ammonium ion, it should be washed with 0.1M ammonia water after washing with water, and then use water washed until the alkali solution completely flows out.

When cleaning the contaminated column, 0.05M dilute sulfuric acid can be used. If the simple organic solvent/water treatment cannot completely remove the impurities adsorbed on the silica gel surface, it is very effective to add 0.05M dilute sulfuric acid after washing.

HPLC Column maintenance
Use a pre-column to protect the analytical column, because silica gel has a certain solubility in polar mobile phase/ionic mobile phase. Please try not to exceed the pH range of 2-7.5 for most reversed-phase columns. Avoid The composition and polarity of the mobile phase change drastically.

Before use, it is necessary to degas and filter the mobile phase. If a polar or ionic buffer solution is used as the mobile phase, the column should be rinsed after the experiment and stored in methanol or acetonitrile Medium. Chloride solvents are corrosive to a certain extent, so please pay attention to them when using, and do not store such solvents in the column and connecting pipe for a long time to avoid corrosion.

Equilibration Regeneration And Maintenance Of HPLC Column

How To Solve The SPE Cartridge Problem?

 Wide application of SPE

There are a wide variety of sample substrates, such as vegetables, fruits, meat, eggs, milk, water, soil, rubber, textiles, etc., whether it is food or environmental samples, the degree of complexity is also different. Simple extraction can be used as a pre-processing method for samples with general complexity, but special pre-processing is required for particularly complex samples, such as using SPE cartridges for further purification to separate the target and impurities, and then use the chromatographic instrument.

When using the SPE pre-processing, the most annoying and maddening problems encountered by the analysis and testing engineers are whether the flow rate is slow, uneven flow rate, blocked, or unable to go down. How to solve it? Hawach would like to talk about it and also welcome to send Hawach your valuable suggestions.

The basic operation of SPE includes five steps: activation, equilibration, sample loading, rinsing, and elution. The problem is nothing more than these steps. Generally, reverse-phase or ion-exchange cartridges use methanol and water for activation and equilibrium, respectively, while normal-phase cartridges use petroleum ether or n-hexane to activate equilibrium.

1)The packing is too tight and the flow rate is too slow.
You can increase the flow rate by pressurizing, or you can purchase products from manufacturers that have strict quality control on the flow rate. The Hawach experiment has a strict quality control range for the flow rate of each batch of SPE cartridges and cartridges outside the quality control range will be rejected.

2)The particle size of the filler is too small, resulting in a slower flow rate.
For example, under the same activation solvent, florisil of 100-200 mesh will be slower than that of 60-100 mesh. You can select the appropriate size of the small cartridge according to the sample matrix type and usage habits.

3)Difference in cartridge tube volume.
500mg 3mL; 500mg 6mL, the height of the filler formed by these two specifications are different. Obviously 500mg 6mL has a large diameter, a low filler height, and a relatively fast flow rate. Just like the morning peak of a subway station, there are many gates, fast passing speed, and few gates. Naturally, it is congested, with slow passing rate. The appropriate column can be selected according to the sample matrix type and usage habits.

4)Wrong order of the added solvent.
For reversed-phase small columns, if the water is accidentally used as the activation solvent, the flow rate will be very slow. Because water has poor wettability for hydrophobic reversed-phase packing, it is accidentally activated by water as methanol.

5)The activation and equilibrium solvents are immiscible.
For example, if methylene chloride is activated and the water balances the small column, everyone will find that after water is added, the flow rate will be slow enough to make you crash. This is caused by the poor miscibility of water and dichloromethane, which can be solved by adding transition solvent methanol, which can be miscible with dichloromethane or water.

6)Air enters the packing.
This reason is relatively common but also difficult to find. SPE cartridges are composed of sieve plates, fillers, and column tubes. They are not an organic whole. Therefore, during transportation, especially long-distance transportation, there will be slight loosening, leading to air entering the filler is generally not easily detected by the naked eye. The air-containing filler causes the activation solvent to flow slowly under the action of air pressure. Speaking of this, you may easily understand why the same batch of small columns may have a slight flow rate irregularity. You can use the SPE device to add positive pressure to pump out the air, and then add the solvent together.

How To Solve The SPE Cartridge Problem?

Sample Is Prone To Membrane Filter Adsorption

The filtered solvent and sample will protect the chromatographic column and liquid phase injection system. Effect on the column: because the packing particles are very fine, the inner voids in the column are very small, and the solvent and the small particles in the sample will clog the column and the sieve plate.

Effects on liquid phase injection system: solvents and small particles in the sample will increase the plug and wear of the injection valve, as well as the wear of the sapphire piston rod and piston in the pump head.

Eliminate the impact of pollution on analysis results. For the commonly used ULTRAVIOLET detector and diode array detector, if the sample concentration is relatively low, the particles will cause large noise, unstable baseline, and infect the normal signal, which will affect the detection results.

Criteria for membrane filter adsorption test

Membrane filter adsorption should be less than 2%. The Recovery or adsorption rate is calculated according to the following formula: Recovery% = A(filtration)/A(before filtration or centrifugation) ×100%. Adsorption rate = 100%-Recovery%. Where: A is UV absorbance or HPLC peak area value. If the recovery rate is between 98% and 102%, i.e. the adsorption rate is no more than 2%, the adsorption effect of the membrane filter can be ignored.

The treatment method is as follows: boil the membrane filter in water for more than 1h and then try again. Change the filter material or brand. Or imported membrane filter. The adsorption effect of the different membrane filter and different formulation process is different, so the correct conclusion should be drawn through experiments.

If the membrane filter does not adsorb the API, but the sample dissolution rate is low, the excipient adsorption API can be considered and then filtered. For varieties with obvious adsorption, the material, brand, and specification of the membrane filter used should be indicated in the internal control standard, as well as the volume of the primary filtrate to be discarded, so as to ensure the accuracy and reproducible of the test results.

What kind of sample is prone to membrane filter adsorption

The adsorbed varieties are usually the main drugs that are insoluble in water and have undergone micronization and other treatments when making preparations. At this time, the particle size of API becomes smaller, the specific surface energy becomes larger, and the electrostatic adsorption capacity is enhanced, so the adsorption effect with the membrane filter will be more obvious.

In the solution of some small size preparations, the concentration of the main drug is low, the volume of the primary filtrate required to reach saturation increases significantly, and the interference will also increase.

Determination of content and related substances

The content and the solvent used by the relevant substances can generally make the main drug completely dissolve out of the sample, so the sample solution can be used to investigate the adsorbability. For the detection of relevant substances, if the proportion of the organic phase in the solvent is higher, more attention should be paid to whether the membrane filter will produce new impurities after filtration.

Sample Is Prone To Membrane Filter Adsorption

How To Selection The Qualitative And Quantitative Filter Paper

How To Selection The Qualitative And Quantitative Filter Paper?

Qualitative filter paper is mainly used for general qualitative analysis and for filtering precipitation or suspension in solution. Qualitative filter paper roll cannot be used for quality analysis.

Qualitative filter paper and quantitative filter paper also have three types: slow, medium, and fast. There are three points to pay attention to when filtering solutions with qualitative filter paper roll:

1. As the mechanical strength and toughness of the filter paper are relatively low, use suction filtration as little as possible. If the filtration speed must be accelerated, in order to prevent filtration failure due to filtration, when the air pump is filtered, it can be stacked in the funnel according to the suction force. 2 to 3 layers of filter paper, when using vacuum filtration, leaking. Put a layer of dense filter cloth first, then put filter paper on it to filter.

2. The filter paper is best not to filter hot concentrated sulfuric acid or nitric acid solution.

3. Generally, natural filtration is used to separate liquids and solid by using the filter paper body and the ability to trap solid particles.

Quantitative filter paper

Quantitative filter paper has a smooth surface, extremely low ash content, strong load capacity, good filtering effect, and ideal particle interception effect. Quantitative vacuum filter paper is mainly used in the gravimetric analysis trial production test and the corresponding analysis experiment in quantitative chemical analysis.

Three filter papers with different flow rates are specially designed to meet the needs of users with different purposes: fast, medium, and slow. Different types of filter papers have different physical and chemical indicators. Quantitative vacuum filter paper has different sizes and specifications, taking into account the filtration speed and particle interception effect, and is mainly used for the determination of cement marks in industrial production, environmental monitoring, and laboratory quantitative analysis.

Quantitative vacuum filter paper has good filtration absorption performance and considerable compressive strength. It is suitable for filtering industrial organic suspended liquids such as petroleum, chemical products, and industrial oils to separate solid and semi-solid impurities. For example, the supporting filter press filters various organic liquids such as transformer oil, turbine oil, molten paraffin grease synthetic resin, dioctyl sebacate, etc. It is also suitable for filtering water or other inorganic liquid suspensions.

Uses: lubricating oil refining, oil refineries, petroleum additives, catalysts, vegetable oils, water filters, paints, coatings, power capacitors, transformers, oleochemicals, fine chemicals, resins, electric power bureaus, power plants, gold mines.

The following points should be considered in the selection of filter paper:
1. The effective area is large, that is, the filter paper uses a large area, the dust holding capacity is large, the resistance is small, and the service life is long. Of course, the cost will increase accordingly.
2. Fiber diameter 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 the higher the binder content, the higher the tensile strength of the paper, the higher the filtration efficiency, the less the linting phenomenon, the lower the dust accumulation of the filter material, the good resistance, but the corresponding increase in resistance.

How To Selection The Qualitative And Quantitative Filter Paper

Conductive Tips

Conductive Tips

Hawach Scientific conductive tips can fit with most commonly HAMILTON and TECAN Automated Liquid Handling in the market. All of the conductive pipette tips are made in a 100,000 class cleaning room with an electronic beam sterilized, which ensures the Non-pyrogenic, Non- endotoxin, DNase, and RNase free.

Hawach conductive filter automation tips used virgin medical conductive polypropylene for liquid level detection to ensure low retention. Highly polished molds with a smooth surface to avoid sample retention, well-designed, and well-manufactured conductive pipette tip have been verified to ensure reliable liquid handling performance. Each conductive tip is inspected online and all functional parts are checked to ensure consistency, accuracy, and precision.

We have a 20μL-1000μL conductive tips volume range and with or without a filter for your option.
Conductive pipette tip OEM is also available.

Hawach conductive filter automation tips can be used for genomics, proteomics, cytomics, immunoassay, metabolomics, biopharmaceutical research, and development.

Feature of conductive tips

1. Conductive tips packed in separate holes to ensure the traceability and uniformity of the electrical conductivity of the product, improves the accuracy of the experimental results, and greatly reduces the deviation between individual products.
2. Smooth inner surface: The unique technology ensures the smooth inner surface of the 20μL-1000μL conductive tips, which greatly reduces the liquid residue.
3. Superhydrophobicity: the filter tips suction porous tissue filtration, to ensure the best performance, and has superhydrophobicity, formed a solid barrier to the aerosol, to eliminate the risk of cross-contamination of samples.
4. The outer packing with high strength bubble shell material, enlarged wall thickness, and anti-impact and anti-drop guarantee the integrity and safety of the conductive filter automation tips under harsh transportation conditions.
5. The mature 20μL-1000μL conductive tips molding process, to ensure the product has good air tightness and adaptability, improve the product in the work of mechanical precision.
6. Electron beam sterilization: safe and fast, without chemical residue. Electron beam sterilization technology is a sterilization technology can directly interact with the nuclear DNA to cut DNA molecular bonds, or chemically react with the water in the cell to form an active state, and act on the intracellular macromolecules to cause reproduction obstacles.

Conductive Tips

Mechanical Strength and Chemical Property of Hydrophilic PVDF Syringe Filters

A syringe filters, which is also called wheel filter, is kind of membrane-based device to remove the particulate impurities from small liquid samples, usually ≤ 100 ml. The scientists use the disposable hydrophilic PVDF syringe filterss are commonly in labs to achieve the fast and efficient filtration, material purification, and sometimes sterilization.

Mechanical Strength and Chemical Property of PTFE Syringe Filter

Hawach hydrophilic PVDF syringe filters is of imported film, provided with high chemical and thermal stability, fast flow rate, strong acid and alkali resistance. And it is also provides with high mechanical strength.

Syringe filter which is made of Nylon 66(Nylon 66) is characterized in the following aspects: microporous membrane has good hydrophilicity, acid and alkali resistance, antioxidants.

It is not only suitable for aqueous solution containing acid and alkali, but also for organic solvents such as alcohols, hydrocarbons, lipids, phenols, ketones and so on.

In application, it does not need to change film and clean filter, and saves complicated and time-consuming preparation work. Moreover, it is mainly used in sample pre-filtration, decontamination of particles, liquids and gases. It is a method to filter HPLC, GC small samples.

Chemical Property of Hydrophilic PVDF syringe filters

The shell is made of polypropylene (PP) material with good chemical stability and makes different colors, which is convenient for users to distinguish products of different gauge materials and avoid confusion.

Membrane of Hawach hydrophilic PVDF syringe filters adopts imported high performance filter membrane, the product quality is stable, the reproducibility is good, so it is the laboratory filtration sample ideal choice. The standard interface is convenient to connect with various syringes, and can also be directly connected to various valves.

Filtration of Hydrophilic PVDF syringe filters

Hawach hydrophilic PVDF syringe filters is suitable for strict application conditions with the following features

The large filtration area makes the treatment capacity and gas flow rate higher than other similar products. Multiple access interfaces available PTFE diaphragm and polypropylene enclosures provide excellent chemical compatibility. Thus it can be used repeatedly without risks. High temperature and high pressure sterilization make it fit for bioreactor and fermenter.

Moreover,it is characterized in low adsorption, high flow rate, high total flux, bidirectional use, 100% integrity test, less dissolution Z, scale amplification, easy to identify pore size, so it can provide various specifications of outlet connection, and causes no particle release, no polyvinyl chloride.

Sterilization Performance of Hydrophilic PVDF syringe filters

Hawach hydrophilic PVDF syringe filters does not need to change film and clean filter, which saves complex and time-consuming preparation and is widely used in the laboratory. The products are mainly used in sample pre-definition, particle removal, sterilization filtration, and so on.

Hawach hydrophilic PVDF syringe filters is used with a disposable syringe, which is a quick, convenient, and reliable filter treatment device for small volume samples used in the laboratory. It is mainly used for sample filtration in chromatographic analysis, it has a good effect on protecting the chromatographic column and carrying a valve from contamination.

Mechanical Strength and Chemical Property of Hydrophilic PVDF Syringe Filters

-56°C Lyophilization Machine; LCD Display

Reasonable vacuum lyophilization machine price for laboratory benchtop lyophilizer

Laboratory benchtop lyophilizer series have 5 types of freeze drying equipment for sale. The most significant difference from small freeze dryer is that the temperature of this series freeze dryers is -56°C. And it can meet most of the needs of most clients. Before buying the lyophilization machine, we must know the important part of the lyophilizer. There are four parts consisting of a laboratory benchtop lyophilizer: refrigeration system, vacuum system, heating system, electrical instrument control system. Drying box, condenser, refrigeration unit, vacuum pump, heating/cooling device are the main components of a dryer. As we all know, the heart of the freeze dryer is the refrigeration system.

As a representative of domestic freeze dryer manufacturers, Hawach has taken the lead in this industry. Our lyophilization machine refrigeration system uses special compressors from well-known international brands. The refrigerants have also selected the internationally recognized stable, safe, and reliable R404 / R23, thereby ensuring the refrigeration effect, economy, and safety. Stability has reached the industry-leading level. While guaranteeing high quality, our laboratory benchtop freeze dryer price is still quite advantageous.

In order to provide the highest quality products, our company strictly controls the quality, especially the circuit. Our laboratory benchtop lyophilizer has leakage protection and anti-dry burning device to avoid circuit safety problems caused by improper operation or excessive consumption. Our vacuum lyophilization machine price is highly competitive when you consider quality.

The Hawach specializes in the production and export of lyophilization machine. The control of circuits and voltage has matured to meet the needs of different countries. The freeze drying equipment for sale of our company is very safe for you to use. Our laboratory benchtop freeze dryer price and quality are also proportional.

Among the series of freeze dryers, small benchtop laboratory freeze dryers are the most popular. Laboratory benchtop freeze dryer price is more suitable than the vertical freeze dryer. With limited budgets and small laboratories, the lyophilization machine is undoubtedly the best choice.

Features of lyophilization machine 56 series

1. The larger the order, the lower the vacuum lyophilization machine price.
2. The fully enclosed imported compressor has higher efficiency and low noise, which speeds up the production process.
3. A large cold trap with a pre-freezing function can realize the effective freezing process.
4. The cold trap is made of stainless steel with a coil inside, which is easy to clean and resistant to corrosion.
5. The patented design of the honeycomb tube speeds up the drying process and saves experimental time.
6. Having an electronic defrost function helps to dry the cold trap after use and prolongs the service life of the cold trap.
7. A transparent bell-type acrylic drying chamber makes the inside of the drying process clearly visible. According to the experimental requirements, it can be adjusted in real-time to achieve the maximum idealization of the experiment.
8. An international standard vacuum port can be connected to most vacuum pumps to meet the needs of different customers.
9. True color operation panel, clear and visible, easy to operate, and record the freeze-drying process with graphics and curves.
10. The large LCD screen display can record operating time, condensing temperature, sample temperature, and vacuum degree can be graphical and curved for up to 30 days.
11. The USB port can be connected to a computer for easy recording.
12. Optional: partition heating function; inert gas inlet inflation valve; -80 degrees Celsius type.
13. The larger the order, the lower the vacuum lyophilization machine price.

Note: The cold trap area and tray size of the LFD-56-18 series are larger than the cold trap area and tray size of the LFD-56-12 series, so the water collection capacity and freeze-drying process are faster. If there are many lyophilized samples and the time required for the experiment, a lyophilizer with a large cold trap area can be preferred.

Hawach Scientific is a professional manufacturer and supplier of the lyophilization machine. It can accept customized products and strive to provide customers with the most suitable machines to help customers achieve achievements in experiments, thereby promoting scientific development. And also our vacuum lyophilization machine price is reasonable. Welcome to contact us!

-56°C Lyophilization Machine; LCD Display

90-280rpm Rotary Evaporator Parts

 As a professional rotary evaporator manufacturer, Hawach developed various slow rotating speed series lab rotary evaporator to suit different requirements of customers.

Besides the RE1 series high end rotary vacuum evaporator, Hawach also has RE120-W, RE200-W, RE280-W series mini rotary evaporator of water bath (oil bath optional), with a slower rotating speed of max. 90-120rpm, 200rpm, and 280rpm, which belongs to the economic rotary evaporator parts.

1. RE120-W series mini rotary evaporator: 90-120rpm, strut press lifting, water bath, digital display rotary evaporator

This series is most price-effective for general lab experiments. For 3L and 5L types, they are with a constant outlet for the continuous experiment.

Item #	RE120-2L-W-D1	RE90-3L-W-D2	RE90-5L-W-D3
Pictures
Volume	2L	3L	5L
Rotate Speed	120rpm	90rpm	90rpm
Display	Digital Display Temp.	Digital Display Temp.	Digital Display Temp.
Temperature	99℃

2. RE200-W series lab rotary evaporator: 200rpm, button press lifting, water bath rotary evaporator

3 different display can choose with the following details:
D1 for digital panel displaying temperature;
D2 for digital panel displaying temperature and rotating speed;
D3 for LCD displaying temperature and rotating speed.

Item #	RE200-2L-W-D1	RE200-2L-W-D2	RE200-2L-W-D3	RE200-5L-W-D2
Pictures
Volume	2L	2L	2L	5L
Rotate Speed	200rpm	200rpm	200rpm	200rpm
Display	Digital Display Temp.	Digital Display Temp.&Rot. Speed	LCD Display Temp&Rot. Speed	Digital Display Temp.&Rot. Speed
Temperature	90℃	90℃	100℃	90℃
Inlet/Outlet	Y/N
Vacuum gear	N
Rotation Power	40W	40W	40W	40W
Total Power	1.5KW	1.5KW	1KW	2KW

3. RE280-W series rotary evaporator parts: 280rpm, strut press lifting, water bath, digital display rotary evaporator

For RE280-W series rotary evaporators: the rotating speed can reach 280rpm; the temperature can reach 100℃ for water bath; effective dual-flux coil condenser increased evaporation process; Integral bath without wire which is safe and easy to clean and add water; Button-press lifting can be used to adjust the position of the rotary bottle in bath; seal ring of PTFE spring composite with the high vacuum; Temperature is shown on the outside of bath; rotary speed can be adjusted by the turning button on the panel.

	Item #	RE280-2L-W-C2
	Volume	2L
	Rotate Speed	280rpm
	Display	Digital Display Temp.
	Temperature	100℃
	Inlet/Outlet	Y/N
	Vacuum gear	N
	Rot. Power	60W
	Total Power	1.3KW

For quotation, other specifications, and customized requirements, please contact rotary evaporator manufacturer for more information.

90-280rpm Rotary Evaporator Parts

Guide to Flash Chromatography Column (Chapter 1)

 Flash chromatography column (Flash Column) is a fast and (usually) easy method to separate complex mixtures. In some experiments, we need to perform a relatively large amount of flash chromatography column to separate about 1g of material.

The principle of chromatography column and thin layer chromatography is the same, but it can be used for the separation of preparative substances. Because we use compressed air to push the solvent through the column, it is called flash chromatography column. This not only makes the separation effect better but also shortens the column time.

Preparation and operation of flash chromatography column:

1. Determine the weight of the dry, solvent-free mixture be separated.

2. Use thin layer chromatography to select the solvent system so that the value of Rf is between 0.2 and 0.3, but if the mixture is complex, this may be unrealistic. In more complicated cases, you may need to use gradient elution. Simply put, it is to continuously increase the polarity of the solvent during the purification and elution process. However, in thin layer chromatography, you must determine which solvent system Will make the different spots in the range of Rf 0.2 ~ 0.3.

3. Determine the method used to load the sample onto the column. You have three choices: clean sample method, solution method, or silica gel adsorption method.

a.Net sample method: If the sample is a non-viscous oil, it is easiest to use the net sample method. You can use a long dropper filter to introduce the liquid into the column, and then rinse with a predetermined solvent system to wash all the components into the chromatography column.

b.Solution method: The clean sample method may sometimes cause the separation column to break. Therefore, for liquids and solids, the more common method is to dissolve the sample in a solvent and then add the solution to the separation column.

The most ideal state is that the Rf of all components in the mixture in the solvent system (usually pentane or hexane) is zero. This is difficult to achieve in most cases, so you can choose a solvent that moves only one compound in the mixture, or you can simply use the eluent of your choice. Remember: the latter two options are risky for difficult separation and purification.

c.Silica gel adsorption method: The last technique is to deposit (adsorb) compounds onto silica gel, which is useful for some liquids and all solids.

Note: Silica gel is acidic, so this step will destroy some acid-sensitive compounds, which usually need to be regenerated on the silica column.

First, dissolve the mixture in methylene chloride in a round bottom flask and add silica gel (the mass of silica gel is about twice the mass of the compound). The solution was concentrated on a rotary evaporator.

Note: Silica gel is a very fine powder and can easily be sucked into the rotary evaporator.

Plug the connector or pump protection device with glass wool to prevent solids from being sucked into the pump. Fast turning can also avoid this problem. When the solids are basically dry (when most of the solids fall off the wall of the container, the solids are already dry), remove the flask from the rotary evaporator, and then use a vacuum pump to exhaust the solvent (assuming there are no volatile substances in the mixture).

Note: Use glass wool to plug the vacuum pump connector, otherwise you may find silica gel (and your compound) enter the vacuum tube and deposit there. Once it is completely dry (no more bubbles in the solid), remove the flask from the vacuum system and scrape the solid from the wall with a clean spatula. Now, you can simply use the powder funnel to add this solid to the top of the separation column, and then rinse with the eluent (1.5mL each time).

Guide to Flash Chromatography Column (Chapter 1)

How To Use The Pipettor ?

 Many people who use pipettors for the first time think that the operation of pipettors is very simple, but it is not. The operation of the pipettor is the first step of a scientific experiment. It is a very basic experimental operation, but most people have prejudices against the operation of the pipettor. In fact, there is much knowledge about pipettor operation. The correct and reasonable use of the pipettor can make the experimental results more accurate and reliable. Let us take a look at how to ensure the accuracy of pipetting.

The correct use of pipettors

1. Different types of micropipettes have their own suction volume ranges. Please use the appropriate range of micro pipettor according to the volume of the solution to be taken.
2. When setting the volume, rotate from low to high, first surpass the desired set value by at least 1/3 turn, and then reverse to the set value; turn from high to low, then directly turn to the set value OK. Do not turn the volume adjustment ring beyond the use range of lowest or highest.
3. The installation of the pipettor tip should adopt the rotary installation method. Place the tip of the pipettor close to the pipettor tip. While pressing down gently, the pipettor in the handle rotates 180 degrees counterclockwise. Do not use excessive force to avoid damaging the pipettor and affecting its extreme accuracy.
4. When transferring liquid, the liquid to be transferred should be sucked and released 2-3 times, so that a homogeneous liquid film can be formed on the inner wall of the tip to ensure the accuracy and accuracy of the pipetting work.
5. When aspirating liquid, the tip immersed in the liquid should be at an appropriate depth, and the liquid aspiration process should be kept as unchanged as possible. Do not immerse the micro pipettor body in the solution.

In the process of sampling and adding samples, it should be noted that the pipettor tip cannot touch other objects to avoid contamination. When aspirating general liquid, press the button with your finger to the first position, keep the micro pipettor as vertical as possible, immerse the micro pipettor in the solution, and then slowly release the button.

After waiting for 1 second, lift the tip off the liquid surface and stay on the wall for 1~3 seconds to make the drop on the outside of the tube tip slip off. Do not release the button too fast, so as to prevent the solution from rushing into the straw and corroding the piston.

When pipetting viscous or volatile liquids, it is easy to cause large volume errors. The following methods are recommended to improve pipetting accuracy. To suck a high-viscosity test solution, please cut the outlet of the micro pipettor head with a blade or scissors first, and pre-moisten it before sucking. Before pipetting the liquid, repeatedly pipettor the liquid several times to pre-wet the tip. When aspirating or discharging liquid, Z stays for a few seconds, especially when pipetting a larger volume of liquid.

Using the reversed-phase pipetting method, press to the second gear when aspirating and slowly release the control button, and part of the liquid remains in the tip. After absorbing the acid or liquid, the micro pipettor should be disassembled, all parts should be rinsed clean, and then the correct combination should be restored to the original state after drying.

6. When discharging liquid, keep a certain inclination, stick the suction head to the inner wall of the container and press the button steadily to the diyi stop point. After 1 second, press the button to the second stop point to discharge the remaining liquid. Press the button while lifting the sampler so that the tip is rubbed against the container wall to release the button. Then use the ejection function of the pipettor itself to discard the tip to the recycling device or waste device, and dispose of it properly.

Pipettor maintenance

1. Regular calibration and maintenance should be carried out according to the use frequency and use environment of the laboratory micro pipettor, and Z should be adjusted and maintained once every quarter.
2. Before starting work every day, check whether there is dust or dirt on the outer surface of the pipettor. If there is, wipe it off carefully. Do not use fire to grill any part of the micro pipettor, and do not absorb solutions with a temperature higher than 700C to avoid steam intrusion and corrosion of the piston.
3. After general use, clean with distilled water and neutral detergent or 60% isopropanol. Then wash it repeatedly with distilled water, remove detergent or isopropanol, and dry. A certain amount of lubricant can be used at the piston after cleaning.
4. In case of severe contamination, refer to the relevant instructions of the pipettor to disassemble the sampler and clean it. The autoclaved part of the pipettor should be autoclaved, but it should not be overheated or placed under pressure to avoid deformation and damage to the pipettor.
5. Check the accuracy of the pipettor by yourself regularly, and send it to the factory for repair if there is any problem.

Pipettors are mainly used in scientific research departments such as environmental protection, medicine, food hygiene, etc., for sampling or adding liquid in biochemical analysis and laboratory tests. It is a piston-type straw that works by using the principle of air discharge.

The capacity of the pipettor is determined by the distance that the piston moves in the piston sleeve, and the liquid is sucked out of the container and moved to a measuring instrument in another container. Correct operation and the use of pipettors can improve work efficiency and prevent fewer errors.

How To Use The Pipettor ?