The Role And Application Of Membrane Filters

The membrane filter is widely used in today’s life, including ultrafiltration membrane, microporous membrane, nanofiltration membrane, microfiltration membrane, mesopore fiber ultrafiltration membrane, etc.

Role of the membrane filter
1. Treatment of solute separation and concentration in solution;
2. Often used for separation of colloidal suspension.

Application
The membrane filter is used for food, beverage, medical medicine, municipal water treatment, industrial high pure water, boiler water, seawater desalination, electronic industry ultra-pure water, wastewater treatment and reuse, material concentration and purification and other industries.

Apply the membrane filter to drinking water
The conventional treatment procedures of the water purification plant are coagulation, precipitation, and filtration. The treatment procedures are simple and only need the filtration membrane device to deal with it. In terms of energy consumption, the full-volume filtration mode of the filter membrane is adopted. Since the pressure is increased through the filter membrane, the raw water pump still needs to be considered in terms of enhancing the pressure.

Types of the membrane filter
At present, according to the form of the membrane filter, it can be divided into coil type, plate frame type, tube type, and hollow fiber type.

The Role And Application Of Membrane Filters

How To Prevent Sample Vials Fragmentation

Hawach ensures the accuracy of each sample vial and cap specification, from the initial design to the final photoelectric scanning inspection process, our strict tolerance control throughout the entire manufacturing process.

Integrity, cleanliness, and uniformity of a sample vial are critical to today’s demanding applications. To prevent contamination and avoid instrument damage, proper selection of spacer is crucial.

The pad of a sample vial may degrade resulting in sample contamination. Rubber pads only stay stable under 90 ℃, and therefore not suitable for high-temperature applications. In general, PTFE-lined silicone rubber spacers are the best choice for all temperatures.

All Hawach sample vials are manufactured under ISO9001 clean environment, and the unique packaging ensures cleanliness and safety during transportation.

How to prevent debris:
1. Select a PTFE-lined spacer to prevent the spacer material from entering the sample;
2. Almost complete removal of debris using pre-perforated spacers;
3. For highly sensitive samples, we recommend using PTFE lining spacers as the PTFE layer acts as a barrier to chemical corrosion.
The sealing of a sample vial is also an important factor affecting the experimental result.

https://www.hawachsamplevial.com/how-to-prevent-sample-vials-fragmentation/

How To Prevent Sample Vials Fragmentation

Rapid Chromatography And Flash Column

Rapid chromatography
Technology for the separation and purification of natural products and biological macromolecules. It has the advantages of easy operation, cheap price, and rapid analysis, and a few other technologies can match the rapid chromatography in the application of purifying organic matter. Rapid chromatography is a typical low-pressure technique. The chromatographic column is filled with silica gel adsorbent with the particle size of 40-60um, and the mobile phase with low viscosity needs to choose a smaller particle size.

Flash column
With the progress of Times, more and more laboratories have a higher degree of automation for separation and purification—rapid chromatograph (low and medium pressure preparative chromatography), in the pharmaceutical outsourcing companies often referred to as the flash column machine. As the name suggests, this is a replacement for the hand-crafted silicone column, which we call the flash column. With the gradual popularity of the domestic machine, the use of higher grade.

Rapid Chromatography And Flash Column

SPE Cartridge Packaging And Application

Most common SPE cartridges are injection syringes made of polyethylene, in which there are two plugs made of polypropylene or fiberglass, with a certain amount of chromatographic adsorbent (filler) between the two plugs.

SPE cartridges without sieve plate
1. Avoid “non-specific adsorption”
2. The packing is stable and can be well fixed
3. Effectively avoid “ditch effect”
4. Improved separation efficiency and sample load.

The capacity of SPE cartridges
The total amount of the target compound plus impurities that can be adsorbed must not exceed the capacity. Otherwise, some target compounds may not be absorbed in the process of sample loading, resulting in low recovery rate.

The packing of the SPE cartridges
It is chromatographic adsorbent normally: take silica gel as matrix; take high polymer as matrix; take non-polar material as main.

The application of SPE cartridges
1. Silica gel bonded phenyl: polar compounds ion exchange and adsorption extraction, such as vitamins.
2. Non-bonded silica gel: polar compound extraction.
3. Silicone bonded procyanidin: reversed-phase extraction, suitable for intermediate-polarity compounds. Positive phase extraction, suitable for polar compounds.
4. Propylamine bonded on silica gel: positive phase extraction, suitable for polar compounds.

SPE Cartridge Packaging And Application

How to Use Pipettes

Before Use

It is important to check the marks, accuracy class and graduation tails before using pipettes.

Imbibition

Use thumb and middle finger of your right hand to pinch the upper end of a pipette, then insert the lower end into the solution to a depth of 10 mm to 20 mm. Use your left hand to hold a rubber suction bulb and connect it to the upper end of the pipette. Suck the solution slowly (Notice: In case of not diluting the solution, the sucked solution cannot be reflowed to the original bottle) and use the index finger of your right hand to take the pipette out.

Turn the pipette horizontally in order to make the solution touch above the graduation and replace the inwall water. Discard the solution from the lower end of the pipette and repeat washing for three times. Finally, you can imbibe the solution to a level of 5 mm above the graduation and use the index finger of your right hand to press the upper end of the pipette immediately.

Adjust Liquid Level

Lift the pipette out of the liquid level and use filter paper to clean the outer wall water. Lose your index finger a little bit to let the solution flow out slowly, then press the upper end of the pipette. Take out of the pipette and insert it into the container to absorb the solution.

Original Data Record

Normally, the relevant original data record of the pipette can be given to two decimal places.

How to Use Pipettes

Use And Precautions Of Diaphragm Vacuum Filtration Pump

Laboratory vacuum filtration equipment is specially designed for laboratory workers to maintain solid-liquid separation of liquid samples.

Operation Procedures of Diaphragm Vacuum Pump

1. Put the glass filter flask on the stainless steel workbench, and insert the silica gel plug of the funnel base into the filter flask.
2. Use pipeline to connect the pump’s connector with the filter flask.
3. Lay the filter membrane on the funnel base, cover the filter flask and rotate gently.
4. Connect the yellow bleeder tube with the bottom drain outlet of the filter flask, and use the fixture to clamp the bleeder tube.
5. Press the power switch to start the pump.
6. Use pressure regulating valve to adjust the vacuum degree (suction) and filtering velocity.

Precautions of Using Diaphragm Vacuum Pump

1. Check the voltage on the data plate of the pump, if it is in line with local voltage.
2. Please use the pump under clean, dust-free and draughty circumstances with the temperature lower than 40℃.
3. The pump must be operated on a horizontal table.
4. Please turn off the power before install and dismantle the silicone tube.
5. Do not move, hit or lean the pump when it is on the operation.

Use And Precautions Of Diaphragm Vacuum Filtration Pump

QuEChERS Prospects

After years of development, the QuEChERS pretreatment method has been continuously improved and broadened by researchers as a simple and rapid residual pretreatment technology.

The application target also has been extended from the highest moisture content of vegetables and fruits at the very beginning to agricultural and sideline products such as meat, milk, grain, oil, etc., and then to the soil, water, pollutants, etc. in the environment, and will be more widely used in various fields in the future.

At present, the extractant and purifying agent are relatively single, and the extraction and purification effects are not ideal for complex matrix samples. Moreover, due to the instability of some pesticides, the technique of using this method to treat multi-residue experiments is not mature enough.

In future research, new extractants and purifiers will be continuously developed. The ratio of extractant, purifying agent and water addition in different samples will be continuously improved, and high-sensitivity and high-throughput testing equipment will be continuously developed. The QuEChERS pretreatment method and various detection equipment combination technologies will become more mature and better to provide better technical support for pesticide residue analysis.

For choosing your QuEChERS packet, contact Hawach!

QuEChERS Prospects

Comparison Between SPE/FLASH and HPLC Column

Columns Ahead Statement

Generally speaking, SPE/FLASH is mainly applied to the pretreatment of samples.

People can easily perceive that SPE/FLASH columns separate salt and sugar, while HPLC ones can make glucose, maltose and sucrose apart from the sugar solution, which posses more similar properties to each other than salt and sugar do. Hence, the HPLC column requires higher power of stationary phases and separating with a corresponding higher prices.

Comparison Between SPE/FLASH and HPLC Column

 

The Differences Between The Filter Bag And The Extraction Thimble

The side of filter-bag where the filtrate comes out is dealt with special singeing treatment, which not only prevents the fibers from staying away from the polluted filtrate effectively but also avoids shortening the service life of the filter-bags caused by the excessive blockage of the filter holes that results in traditional roll pressing treatment.

Hawach filter bag is suitable for filtering general industrial liquids such as electroplating E, D paint, ink, paint, food, and other chemical medicinal liquids. And the bags are acid-resistant, alkali-resistant fibers which have high mechanical strength and can be used repeatedly. The filter bag applied to dust remover has excellent stability and heat resistance, which can represent the highest performance in the filter material industry. It is also the best kind of common filter materials. It has high filtration efficiency and accuracy. The commonly used filter materials are PE, PP, PTFE, PMIA, NMO, etc.

Hawach extraction thimble is a kind of cylindrical element used for filtering, which is generally used to filter gas medium and liquid medium. Compared with the filter-bag, the extraction thimble has some advantages. The extraction thimble occupies less space and is easy to clear. The extraction thimble has a longer life and lower cost.

The Differences Between The Filter Bag And The Extraction Thimble

Application Of Syringe Filters

Syringe filters are filters for standard lab samples, providing a fast, convenient and reliable way to filter samples. It is widely used in colloid separation, microanalysis, gravimetric analysis, and aseptic test.

Syringe filters handle chromatographic samples without introducing other impurities into the process. The material of the membrane and shell structure is very important. Because of the precision of the chromatographic system and the accuracy of the result analysis, it is very important to filter the samples.

Application of syringe filters
1. Sample prefiltration;
2. Clarifying and removing particles;
3. Liquid and gas filtration.

Syringe filters have different filter membranes (PTFE, PES, nylon 6, nylon 66 and PVDF) selection and each filter membrane has different apertures.
Common syringe filters include edge filters and ultrasonic filters:

An edge filter: the disadvantage of the traditional filter is easy blasting. An edge filter is suitable for ventilation, gas purification, gas sterilization, and water resistance.

An ultrasonic filter: it adopts new ultrasonic welding technology and new double-layer membrane design, which can filter large particles in advance, especially suitable for filtering large particles and multi-impurity materials.

Application Of Syringe Filters

Hawach PTFE Pleated Membrane Filter Cartridges

Hawach PTFE pleated membrane filter cartridges is made of polytetrafluoroethylene film and is widely used in gas sterilization filtration of pharmaceutical, biological products, food and beverage, and fermentation industries. The natural hydrophobic, double-layered PTFE membrane construction and 100% integrity testing ensure absolute sterilization of the media.

PTFE pleated membrane filter cartridges characteristics
1. Hydrophobic and hydrophilic PTFE membranes are available
2. Excellent resistance to organic and inorganic chemical corrosion
3. Can be used for strong solvent, strong corrosive liquid, strong oxidizing liquid, particle removal, sterilization filtration

Filter specifications
Standard sizes: 5”, 10”, 20”, 30”, 40″,…,70″
Filtration accuracy: 0.1um, 0.22um, 0.45um, 1um, 5um, 10um, 20um, 50um
The sealing ring is: silicone rubber, EPDM rubber, fluorine rubber, fluorine-containing rubber

Typical application
1. High-precision filtering of terminals in the microelectronics industry.
2. Low-temperature materials in refrigeration, such as liquid methane, liquid ammonia, and various refrigerants.
3. Weak acid corrosive materials in petrochemical production, such as water, ammonia, oil, hydrocarbons, etc.
4. Corrosive materials in chemical production, such as caustic soda, soda ash, sulfuric acid, carbonic acid, acetic acid, and ester acid.
5. Light-weight foods and pharmaceuticals that have hygienic requirements, such as beer, beverages, dairy products, and medical supplies.

Hawach PTFE Pleated Membrane Filter Cartridges

The Knowledge Of HPLC Column Packing

The common packing materials we use in HPLC columns are silica, hydroxyapatite media and polymeric resins, as many of types of packing used for gravity or low-pressure chromatography cannot stand the high pressures which are used in an HPLC separating system.

Due to the increased surface area, smaller-diameter beads can improve the sensitivity of separation. For an analytical HPLC column, media bead diameters are usually in the range of 1.8–5 μm. We should set the lower limit of bead size, as column pressure increases and bead diameter is reduced for a given flow rate, at the same time.

In the early time, we pack early HPLC columns with irregularly shaped silica particles to increase surface area. When scientists found that the spherical shape could provide increased efficiency and the porosity of the surface area, irregular silica was replaced by spherical porous silica.

The Knowledge Of HPLC Column Packing

What Are The Applications Of Ion-Exchange Solid Phase Extraction?

Ion-exchange solid phase extraction is widely used in biological samples and environmental monitoring.

During the extraction process, the pH of the sample is adjusted so that the solute is easily ionized. The solute is exchanged from the resin by changing the pH or increasing the strength of the competing ions during elution.

The pH of the organic base or acid is 50% protonated or ionized near the pKa. If the pH of the two units is lowered or increased, respectively, 99% of the base or acid is ionized, so the elution should also be increased or Lower the pH of the two units.

The sensitivity of ion exchange solid phase extraction is affected by pH, interionic force, flow rate and buffer ionic strength. The higher the competitive ionic strength in the sample matrix, the lower the extraction efficiency. For example, citric acid can compete for anion exchange sites.

In addition, some adsorbents can chelate with certain metal ions, such as iminodiacetic acid and Na+, which can effectively separate certain metal ions. Hawach offers you ion-exchange solid phase extraction cartridges.

What Are The Applications Of Ion-Exchange Solid Phase Extraction?

Six Major Operational Misunderstandings Using Pipettes

Pipettes are widely used in the laboratory. Proper operation and use of pipettes can improve work efficiency. What are the six common operational misunderstandings of pipettes? Pipettes are widely used in laboratories. The correct operation and the use of pipettes can improve work efficiency. What are the common 6 operating mistakes of using pipettes:

Misunderstanding 1. When assembling the tip, the force is too strong. The result is that the tip is difficult to be detached correctly: no need to use excessive force, select the tip that matches the pipette.

Misunderstanding 2. When pipetting, the pipette itself tilts: The pipetting is inaccurate and correct: vertical pipetting, slow suction and slow release.

Misunderstanding 3. Lay the pipette with a residual liquid tip. Consequence: The liquid reverses corrosion. The piston spring is correct: the pipette should be hung on the pipette holder.

Misunderstanding 4. Use a large-scale pipette to remove small volume samples. Consequences: Inaccurate pipetting. Correct: Pipettes with appropriate range should be selected.

Misunderstanding 5. directly press the second file to the correct absorption: it should be operated according to standard methods.

Misunderstanding 6. Cleaning the pipette with acetone or highly corrosive liquids: Damage to the pipette. The correct method: look at the instructions in detail, do not use corrosive liquids for cleaning. In the process of operating the pipette, be sure to avoid similar problems, bearing in mind the above six major misunderstandings.

Six Major Operational Misunderstandings Using Pipettes

Overview of QuEChERS Technology

QuEChERS, composed with Quick, Easy, Cheap, Effective, Rugged and Safe, is a latest developed sample pretreatment technology of detecting agricultural products, which was developed by one professor from the United States Department of Agriculture in 2003.

Principle

Its principle is similar to that of High-Performance Liquid Chromatography (HPLC) and Solid Phase Extraction (SPE). Both of them utilize the interaction between adsorbents and impurities of the matrix adsorbing impurities to remove impurities and realize purification.

General Steps

The steps of QuEChERS technology can be simply summarized as follows.

1. Crush samples
2. Extract and separate of acetonitrile of the single solvent
3. Add MgSO4 and other salts to remove water
4. Add ethylenediamine-N-propyl silane (PSA) or other adsorbents to remove impurities
5. Detect the supernatant

Advantages

The QuEChERS also has the following advantages. (three of the all are listed only)

1.High Recovery Rate
The recovery rate of a large number of polar and volatile pesticides is more than 85%;
2.High Accuracy and Precision
This can be modified by the internal standard method.
3.A Wide Range of Analyzable Pesticides
Including polar and non-polar pesticides, experts can apply this technology to acquire a higher recovery rate.

Overview of QuEChERS Technology

Testing Report Of Glass Fiber Extraction Thimble

The thimble is utilized in extraction, so the dissolution rate of impurities is a comparatively deductive target. For the deficient data of cellulose extraction thimbles, the mental content in glass fiber ones has to be tested, and respective results of different sizes are listed.

Even though they have similar characteristics in maximum temperature, DOP retention, weight loss and composition, which separately are 600C(usually 500C for big brands), higher than 99.99% (with the condition of at least 0.3um, oil mist method GB6165-85), lower than 0.2m(m ranges from m1 to m2, and m1 means the weight after dried at use-temperature for 60 min with similar m2 – the weight after dried at use-temperature of 120 minutes.), and super-fine glass micro-fiber.

Hence, the differences between products indicate in the background response and flow pressure.

SLGET32120 Glass Fiber Extraction Thimbles
57.22 % silicon dioxide(SiO2), 0.3% iron dioxide(Fe2O3) and 14.63% aluminium oxide(Al2O3) are deducted. The flow pressure is 14 to 16 mmHg.

SLGET2590 Glass Fiber Extraction Thimbles
It has been figured out in the samplings that 16.12% calcium oxide(CaO) and 3.66% magnesium oxide(MgO). 16 to 18 mmHg of flow pressure is checked.

SLGET2870 Glass Fiber Extraction Thimbles
0.16% calcium oxide(CaO) and 0.38% sodium oxide(Na2O) exist with 18-20 mmHg flow pressure.

Testing Report Of Glass Fiber Extraction Thimble

How To Use The Bottle-Top Dispensers

This article will focus on the methods of using the bottle-top dispensers.

1. Put the intake pipe into the dispenser and then tighten the nut.
2. Put the drain pipe into the dispenser and then tighten it.
3. Take off the cap of the drain pipe and put it under the drain pipe
4. Adjust the volume from zero to numerical value by rotating scale
5. Start the exhaust process. First, we should ensure the cap of the drain pipe open. Second, we lift the piston for a certain distance and then press it down. At last, we repeat the previous steps for several times until we see the bubbles are completely eliminated through the observation window.
6. Prepare the separation after the exhaust process. And pay attention that if we always can see the bubbles, we should check whether the suction pipe or other valves are installed correctly.
7. Adjust the volume from zero to numerical value from an arbitrary direction.
8. Press the piston to the bottom, and then adjust the knob to zero scales. Lock the dispenser.
9. Transfer the liquid. The piston is lifted stably to the top and then pressed equally stable to the bottom. There is a complete separation process. In this process, we should care that if the piston is lifted too fast, there may be excessive drops dripping into the piston which will cause errors.

Lock the dispensers after separating the liquid. That’s all for using the bottle-top dispensers.

How To Use The Bottle-Top Dispensers

Learn About Quantitative Filter Papers

Quantitative filter papers are widely used for quantitative and gravimetric analysis in the lab. To make them ash-less and achieve high purity, a special production process with acid is required in production, washing with HF or HCl acids, cleaning with demineralized water followed. The specific processes make the quantitative filter papers achieve two characters: high resistance to wet state and low ash content.

Called as ash-free filter paper as well, the quantitative filter papers can be divided into three formats, ashless, hardened low ash and hardened ashless.

With 0.007% ash maximum for grades 40 to 44, ashless quantitative filter papers are ideals for a wide range of critical analytical filtration procedures.

Treated with a strong acid to remove trace metals and produce high wet strength and chemical resistance, hardened low ash quantitative filter papers have 0.015% ash maximum. These filters are particularly used for vacuum filtration, as the tough smooth surface of the filter can recover precipitates easily. Its high wet strength and chemical resistance are similar to the acid hardened ashless filter papers.

And hardened ashless quantitative filter papers, with 0.006% ash maximum, are hardened by acid. The process gives high wet strength and chemical resistance with extremely low ash content.

Learn About Quantitative Filter Papers

Pipettes & Bottle-Top Dispenser

Let me really invite the protagonist of this promotion – Pipettes & bottle-top. The pipette is one of the most commonly used popular pipettes used by the experimenters, and the bottle-top dispenser is also a common instrument used in experiments. They are clearly nice and can really help out with a lot of operational difficulties in the experiment.

Basic knowledge

In general, they are a common device for removing liquids. The pipette is suitable for removing small amounts of liquid, and the bottle-top dispenser is used to take large amounts of solution.

Scope of application

The bottle-top dispenser is suitable for general acids/bases and low concentration of strong acids/alkalis/oxidants. It can perform accurate and repeatable liquid separation operation without waste of reagents, and at the same time provide safety assurance for operators and experimental environment.

In the study of analytical testing, the pipette is generally used to measure a small amount or a small amount of liquid. Different specifications or sizes of pipettes are used with the corresponding sizes of the spearhead.

Maintain

The shapes produced by different manufacturers and are slightly different, but the maintain principle for removing liquids are basically the same：removal of pollutants timely；clean or disinfect regularly; avoid placing at high temperature to prevent deformation/leakage/misalignment.

Pipettes & Bottle-Top Dispenser

The Source And Control Of Pollution In Sampling

Source of Pollution
Potential sources of pollution include the following:
1. Pollution from the previous sample which remained in the sample vial.
2. Pollution from the sampling position.
3. Pollution from water remained on the sampling rope.
4. Pollution from the sample vial itself.
5. Pollution from the vial cap and vial neck by dust and water.
6. Pollution from laboratory workers’ hands, gloves, and improper operation.
7. Pollution from waste gas emissions inside the sampling equipment.
8. Pollution from impurities in the fixing agent.

Control of Pollution
The frequently-used measures to control pollution in sampling include the following:
1. Keep the sample vials far away from pollution to ensure high-quality data analysis.
2. Avoid churning the waters in sampling position.
3. Thoroughly clean the sample vials and equipment.
4. Store the sample vials in a safe place to prevent vial caps and vial corks from being polluted.
5. Scrub and dry the sampling ropes after sampling, and store them afterward.
6. It is quite important to avoid touching samples by hands and gloves in the sampling of microorganism.
7. After sampling, check if there are big particles inside each sample. Resampling if necessary.

The Source And Control Of Pollution In Sampling

How To Choose Syringe Filters In The Lab?

Consisting of a filter medium and housing or holder that constrains and supports the syringe filter media in the sample’s path, filters are good tools when you need removing particulates from samples in the lab.

We have three basic types of laboratory filters.

Membrane filters size rating of the membrane is determined the size of the pores. Centrifugal filters are suitable for separating such as protein or nucleic acid desalting and concentration. These devices drive the liquid through the filter through centrifugal force. And syringe filters which consist of a filter element and housing assembly are used when a sample must be filtered before entering a syringe.

To select the best filter for your process, ask yourself the following questions:

1. What are you going to filter?
2. What is the size and nature of the particles or molecules to be removed?
3. Chemical composition of your sample.
4. Viscosity.
5. Suitable temperature.

More to be concerned upon your applications:
1. To achieve the separation, what pore size or nominal molecular weight rating is required?
2. Do you need a sterilizing filtration?
3. How quickly do you need to filter?
4. Pressure-driven or vacuum-driven filtration?

Now, your knowledge is improved to obtain accurate separation of your sample, mobile phase or other liquid.

How To Choose Syringe Filters In The Lab?

The Method Of Cleaning Sample Vial

The cleaning of sample vial is very important. Usually, according to the principle of glass instrument washing and the degree of pollution to choose cleaning methods, there is no fixed mode. The specific methods are as follows:

Method one:
1. Dry the sample in the sample vial.
2. Immerse in 95% alcohol, wash twice with ultrasound and then dry, because alcohol is easy to enter 1.5mL vial, and can be soluble with most organic solvents to achieve;
3. Pour in clear water and wash twice with ultrasound.
4. Pour the lotion in the drying vial and bake at 110 degrees Celsius for 1-2 hours. It can’t bake at high temperature.
5. Cooling and preserving.

Method two:
1. Rinse the tap water several times.
2. Put it in a beaker filled with pure water and ultrasonic for 15 minutes.
3. Change the water and ultrasound for 15 minutes.
4. Finally, take out the natural air-drying.

Method three:
1. Soak in methanol for 20 minutes, then dry the methanol.
2. Fill the sample bottle with water, wash it with ultrasound for 20 minutes, and then dry it.
3. Finally, the sample vial will be dried.

The Method Of Cleaning Sample Vial

The History Of Flash Column Chromatography

Flash column chromatography method is to separate the constituents from the mixture and thus purify it. In a word, flash column chromatography makes the samples go through the column which is filled with gel to achieve separation.

In the beginning, the founder of flash column chromatography, Mr. Still together with his colleagues had been using medium pressure chromatography and short column chromatography to replace long column chromatography. Later they decided to combine the above two methods to overcome the defects of time-consuming and low recovery.

Initially, the gel used for filling the column is silica gel, and it is still widely applied nowadays. Laboratory workers use air pressure to push the solvent through the silica gel column, and then use the same solvent to make the sample go through the column. At last, they collect purified constituent. The whole process costs about 5 to 10 minutes.

Since the first outcome of silica gel flash column chromatography, it has been widely applied in the field of organic chemistry. Compared with high-performance liquid chromatography, the resolution ratio of flash column chromatography has reached the medium level.

The History Of Flash Column Chromatography

PVDF Membrane Filter Media Introduction

The hydrophilic polyvinylidene fluoride membrane filter is commonly used for the purification and filtration such as tissue culture media, additives, and other sterilization filtration solvents, chemical raw materials, aseptic processing of reagents, and for filtration of high-temperature liquid, etc.

Features:
PVDF is with high mechanical strength, high tensile strength, good heat resistance, and chemical stability, low protein adsorption rate; strong negative electrostatic and hydrophobic; hydrophobic and hydrophilic. However, it cannot tolerate acetone, DMSO, THF, DMF, dichloromethane, chloroform, etc.

Applications:
The Hydrophobic and hydrophilic PVDF membrane filter and syringe filters are mainly used for gas filtration and high-temperature liquid filtration;
The hydrophilic polyvinylidene fluoride membrane Filter available from membrane filters discs and membrane filter roll.
The hydrophilic polyvinylidene fluoride syringe filter available of non-sterile and sterile filters, complete filter size and pore size in supply for customers choice.

PVDF Membrane Filter Media Introduction

Introduction of Sampling System for Cationic Chromatographic Columns

The cation chromatography column is a kind of high-performance liquid chromatography, which is a liquid chromatography method for analyzing anions and cations. The method has the advantages of good selectivity, sensitivity, rapidity, and simplicity, and can simultaneously measure various components.
The catalytic column injection system
There are three main types of ion chromatography injections: pneumatic, manual, and automatic injection.

First, the manual injection valve
The manual injection uses a six-way valve, which works in the same way as HPLC, but the injection volume is larger than HPLC, generally 50 μL. The sample is first filled with a metering tube in a low-pressure state, and when the valve is rotated clockwise to another position, a sample of a fixed volume stored in the metering tube is sent to the separation system.

Second, the pneumatic injection valve
The pneumatic valve is powered by certain helium or nitrogen gas pressure. After the two-way four-way loading of the quantitative tube, sampling and injection are carried out, which effectively reduces the error caused by the different movements of the manual injection.

Third, automatic injection
The autosampler is automatically controlled by the chromatography workstation to perform a series of manipulations such as sampling, injection, and cleaning. The operator only needs to load the samples into the storage machine in sequence. The working steps of the disc type autosampler are as follows:

(1) The motor drives the storage tray to rotate, and the sample to be analyzed is placed directly below the sampling needle.
(2) The motor rotates forward, the screw moves the slider downward, inserts the sampling needle into the sample plastic cover, the slider continues to move down, pushes the bottle cap into the bottle, and the sample flows through the pipe under the cap extrusion Sample valve quantitative tube, complete the sampling action.
(3) The injection valve is switched to complete the injection.
(4) The motor is reversed, the screw moves the slider up, and the sampling needle returns to the original position.
The automated injection can achieve a wide range of sample injections.

Introduction of Sampling System for Cationic Chromatographic Columns