The Concept of Flash Column Chromatography

Developed in the 1970s, flash column chromatography is the method of isolating and purifying a component from a mixture by passing the sample through the flash column filled with a gel.

The inventors of flash column chromatography were using medium pressure chromatography and short column chromatography to replace the long column chromatography. And then they found a new way of combining the pressure and short column together to avoid taking too much time and achieving poor recovery.

The technique of flash column chromatography is well known because it presents the faster flow rates of the solvent than simple gravity flow. The silica gel was used as the original gel to line the column. And the silica gel is still in practice widely nowadays.

The scientists in the lab use air pressure to drive a solvent through the silica gel column, following up with column compression. After the sample is applied, the solvent will pass the sample through the column. And then we can collect the purified components or fractions. The process often takes about 5-10 minutes.

The Concept of Flash Column Chromatography

Capsule Filters Introduction

Capsule filters, also known as the integrated filter, adopt fold-type inlet membrane, which has a large surface area and are suitable for the filtration of large-volume solutions.
Capsule filters, which are made of polypropylene, are free of adhesives and other chemicals and are not meant to contaminate the sample.
Types of capsule filters
1. RFPT filter capsules use hydrophobic polytetrafluoroethylene (PTFE) filter membrane;
2. RFPP filter capsules use hydrophilic polypropylene (PP) filter membrane;
3. RFPN filter capsules use nylon membrane.
Features of capsule filters
With housing, can be used directly, no stainless steel housing, cost savings. Simple installation, easy to use, reduce spatter and leakage. Available in various sizes and shapes (thread, hose, etc.) to meet a variety of conversion interface. Suitable for filtering 1-20 liters of laboratory filtration and all kinds of machine terminal filtration.
Application of capsule filters
1. Prefiltration of reverse osmosis and ultrafiltration;
2. Filtration of aqueous and solvent samples;
3. Filtration of chemical industry ink and fuel, development fluid;
4. Filtration of viscous liquids in the food industry;
5. Filtration of corrosive liquids in the pharmaceutical industry.
Capsule Filters Introduction

The Use of Microporous Membrane

Laboratory workers use a membrane to filter two phases. Actually, the membrane is a kind of media. According to different aperture sizes, filter membranes can be divided into the microporous membrane, ultrafiltration membrane, nanofiltration membrane and reverse osmosis membranes. Specifically, the microporous membrane is commonly used in laboratories with an aperture size of 0.1 to 1 micron. Talking about microporous membrane, it is mainly made from refined nitrocotton with moderate cellulose acetate, acetone, n-butyl alcohol, ethyl alcohol, etc. It is important to filter solvent and samples with the microporous membrane in the laboratory, basically, there are two reasonable concerns. One is to protect the chromatographic column and instrument. The other is to prevent pollution from affecting the analysis results. For example, for the ultraviolet detector, if sample concentration is low to a certain degree, the particle will cause serious noise to interfere with normal signals and finally decrease the SNR (Signal to Noise Ratio) and affect the test results.

Choose of Microporous Membrane
PTFE: Apply to all solvent, acid and salt.
Nylon: Apply to the most organic solvent and hydro solvent.
RC: Apply to water-soluble sample and an organic solvent.
PES: Apply to water-soluble sample.

Caution against Using of Microporous Membrane
1. Using a syringe with volume of fewer than 10 ml may cause burst due to high pressure.
2. Different membrane materials will produce different absorption efficiency, but do remember to choose the microporous membrane in accordance with the recommendation in operation specification.

The Use of Microporous Membrane

Preparation of Mobile Phase of HPLC Column

HPLC is the separation of sample components between the column packing and the mobile phase for mass exchange. Therefore, the mobile phase is required to have the following characteristics:

a. the flow relative to the sample has a certain solubility, to ensure that the sample components will not precipitate in the HPLC column(or remain in the column for a long time).

b. The mobile phase is inert and does not react chemically with the sample (except in special cases).

c. The viscosity of the mobile phase should be as small as possible so that a good separation effect can be obtained when using a longer analytical column; at the same time, the HPLC column pressure drop is reduced and the life of the liquid pump is prolonged (the temperature can be lowered to reduce the viscosity of the mobile phase).

d. The physical and chemical properties of the mobile phase should be compatible with the detector used. If a UV detector is used, it is best to use a solvent with a lower UV absorption.

e. The boiling point of the mobile phase should not be too low, otherwise, bubbles will be easily generated, which may make the experiment impossible.

f. After the mobile phase is prepared, it must be degassed. Removal of traces of gases dissolved in the mobile phase facilitates both the detection and prevention of trace oxygen in the mobile phase from interacting with the sample.

Preparation of Mobile Phase of HPLC Column

How Does SPE Extraction Work During the Whole Process?

Activation, also known as solvation, add a suitable solvent to expand the functional groups on the adsorbent and remove possible interferences on the adsorbent.

Equilibrium, remove the activated solvent to create a suitable solvent environment for sampling. Usually, use the same solvent of the sample solution. But for the ion exchange SPE cartridges, use the contrary solvent to the sample solution.

Retention, when the sample solution passes through the adsorbent, and the force between the adsorbent and certain compounds exceeds the force between the latter and the solvent, the compounds are fixed by the adsorbent, thus called retention; washing, after sampling, some of the interfering substances are retained together with the target compound.

It is necessary to add a suitable solution to remove the interferences to the greatest extent without affecting the retention of the target compound. Usually, the sample solvent for washing does not affect the recovery rate.

Elution, the strong elution ability solvent passes through the adsorbent to interrupt the interaction between the adsorbent and the retained compound so that these compounds flow out from the adsorbent with the solvent. Usually, the elution solvent which can only elute the target compound is the best choice.

How Does SPE Extraction Work During the Whole Process?

Pipette Suction Angle

n order to facilitate the observation of the condition of the sample in the tip during the pipetting process, many users will keep the pipette at an angle of 45 degrees or even closer to the horizontal angle during the pipetting process. But this is wrong again.

1. When removing a sample that approaches or reaches the maximum volume of the tip, the large angle of the pipette can easily cause the liquid to slip into the handle of the pipette, thereby contaminating or even corroding the piston of the pipette. Causing cross-contamination of the sample;

2. The large angle of the pipette tilt will also increase the contact surface of the outer wall of the tip with the liquid so that the liquid remaining on the outer wall when the tip leaves the liquid surface is more.

It is easy to follow the inside of the tip when draining The liquid leaves the tip together, which reduces the precision of the pipetting, and for these small amounts of liquid (for example, 2 ul and 10 ul) pipettes, the damage to the accuracy is likely to be fatal!

Pipette Suction Angle

Features of Vacuum Filtration

Vacuum filtration is a method of accelerating the water filtration by taking advantage of the negative pressure created by pumping, applied disciplines of which include materials science and technology, inorganic non-metallic materials, ceramics, and ceramic material technology.

Features of vacuum filtration pump
1. Advanced design, high working efficiency and long service life;
2. No need for any working medium and no pollution;
3. Ideal vacuum degree and high air velocity;
4. The motors provided by ODM;
5. Equipped with thermal power saver;
6. Non-friction membrane body movement, no heat generation, no friction loss;
7. Designed with an automatic cooling and air exhaust system.

Features of stainless steel multi-connection vacuum filtration
1. Easy to disinfect at high temperature, resistant to high temperature and corrosion.
2. Multiple samples can be processed at the same time.

Solvent filter of vacuum filtration
1. High quality glass material;
2. Good pressure resistance;
3. Fast flow and good sealing performance;
4. The size and specification meet the international standard.

Features of Vacuum Filtration

The Product Composition of QuEChERS

The product mainly includes two parts: extraction boxes and purification boxes. Extraction boxes include salt bags and 50 ml centrifugal tubes. Due to the high transportation cost of 50 ml centrifugal tubes and the general unacceptability of customer laboratories, more customers will buy salt bags directly. In order to meet different customer needs, two kinds of products are designed, one is salt bag, the other is salt bag + 50 ml centrifugal tube. The purifying box of this kind of product is composed of adsorbent and centrifugal tube, including two specifications of 2 ml and 15 ml of the centrifugal tube. The adsorbent can be directly placed in the centrifugal tube. Another kind of product is a complete set, that is, extraction box + purification box. The customers of this combination product can do a whole set of experiments once they get it.

  

Therefore, in summary, the products mentioned above are divided into three categories, which are as follows:
Category 1: Extraction tube + Bagged Salt Bag： + Purification tube
Category 2: Bagged Salt Bag + Purification tube containing empty tube + salt Bag
Category 3: Only empty tube, only salt, only purification tube, only adsorbent.

The Product Composition of QuEChERS

Material and Application of Extraction Thimbles

We recommend materials and applications of two kinds of extraction thimbles in Hawach.

The material of extraction thimbles

Due to different materials of extraction thimbles, two types of extraction thimbles are sold in the Chinese market. Cellulose extraction thimbles: high-grade alpha cellulose/seamless noble cellulose and linter of cotton without any binding elements(60% high-clean poplar fiber +40% refined cotton fiber).

Glass fiber extraction thimbles: the advanced special glass wool

Application differences and emphases

Cellulose extraction thimbles are particularly suitable for the extraction of indoor dust /toxic organics (phthalic acid) / natural substances, lacquer and binder analysis in paint colors, dust and tar determination in gases, and other similar simple Soxhlet extraction of organic components.

Glass fiber extraction thimbles are always used in specific Soxhlet extraction, such as temperature higher than 120℃, strong acid cellulose filter cartridge is not suitable for. Glass fiber extraction thimbles are also applicable to the detection of stationary pollution sources: flue gas, smoke, and dust, such as cadmium, nickel, tin, and fluorine, etc.

In addition, it is a highly efficient filter for dust, acid mist, beryllium, and other harmful substances, environmental /air exhaust detection, such as arsenic, dioxin, lead, asphalt smoke, sulfuric acid fog.

Material and Application of Extraction Thimbles

Material and Application of Extraction Thimbles

We recommend materials and applications of two kinds of extraction thimbles in Hawach.

The material of extraction thimbles

Due to different materials of extraction thimbles, two types of extraction thimbles are sold in the Chinese market. Cellulose extraction thimbles: high-grade alpha cellulose/seamless noble cellulose and linter of cotton without any binding elements(60% high-clean poplar fiber +40% refined cotton fiber).

Glass fiber extraction thimbles: the advanced special glass wool

Application differences and emphases

Cellulose extraction thimbles are particularly suitable for the extraction of indoor dust /toxic organics (phthalic acid) / natural substances, lacquer and binder analysis in paint colors, dust and tar determination in gases, and other similar simple Soxhlet extraction of organic components.

Glass fiber extraction thimbles are always used in specific Soxhlet extraction, such as temperature higher than 120℃, strong acid cellulose filter cartridge is not suitable for. Glass fiber extraction thimbles are also applicable to the detection of stationary pollution sources: flue gas, smoke, and dust, such as cadmium, nickel, tin, and fluorine, etc.

In addition, it is a highly efficient filter for dust, acid mist, beryllium, and other harmful substances, environmental /air exhaust detection, such as arsenic, dioxin, lead, asphalt smoke, sulfuric acid fog.

Material and Application of Extraction Thimbles

What is the Bottle-Top Dispenser?

A bottle-top dispenser is a device installed at the mouth of a solvent bottle to take a large amount of solution and has been constantly updated and improved to meet the growing operational requirements of the laboratory for more than ten years.
There are two kinds of bottle-top dispensers: mechanical (0.5 – 5ml, 1 – 10ml, 2.5 – 25ml and 5 – 50ml) and electronic (0.1 – 99.9ml).
Installation instructions of bottle-top dispensers
1. Install the suction pipe;
2. Install the return pipe;
3. Install the distribution pipe;
4. Install the reagent bottle;
5. Prepare the suction and separation;i
6. Get rid of air bubbles;
7. Quantitative liquid separation;
8. Handle after use;
9. Simple maintain and cleaning.
All-purpose/hydrofluoric acid bottle-top dispensers
They are suitable for hydrofluoric acid, strong acid, nicotinic acid, alkali, solvent and extreme dangerous liquid. The valve has no spring structure, no corrosion and metal ion contamination reagent, suitable for trace analysis. Strengthen the safety valve to prevent the release of niacin/odor chemical liquid odor.
The materials of bottle-top dispensers are mainly optical glass, Al2O3, ETFE, PFA, FEP, PTFE, platinum-iridium alloy, PP (safety helmet).
What is the Bottle-Top Dispenser?

The Overview of Filter Papers

What is Filter Paper?

Filter paper is a kind of semi-permeable paper barrier placed vertically above a liquid or air. It is widely applied to separate purified substances from liquids or gas. In science labs the filter papers can be used for extract solids from fluid and also is capable of removing sand from water.

Properties

Filter papers possess numerous properties. Its notably essential parameters include wet intensity, porosity, particle retention, compatibility and capacity of separation.
What is more, two mechanisms of filter papers filtration are obvious–volume and surface. Based on volume filtration the granules can be caught in the filter paper, while applying to the surface one, particles only get stuck on the surface of the paper.

Types

Here we mainly sort filter papers out of two types. One is utilized in most living conditions. People are seemingly more familiar with coffee filters, oil filters, fuel filters and even the tea bag is on the list.

  
However, another type is specialized for laboratories and sometimes named Laboratory Filters. Surprisingly, this one covers loads of subclasses such as Qualitative filter papers, Chromatography Papers, Extraction Thimbles, Glass Fiber Filters, Quartz Fiber Filter and PTFE filters.

The Overview of Filter Papers

Several Attentions about Using and Maintaining Chromatographic Columns

It is important for the experimenters to use and maintain chromatographic columns correctly. They should focus on many some things so as to protect the columns in the using process. Here we talk about several attentions.

Avoid changing pressure and temperature dramatically and any mechanical vibration. Sudden changes in temperature affect the filling conditions in the columns. And sudden changes of column pressure may loosen the fillers. Consequently, people should adjust the flow rate of the fillers slowly to protect the fillers.

Change the composition of the solvents gradually. The experimenters should change the composition of the solvents gradually, especially in the reversed-phase chromatography.

Do not backwash the columns. Generally speaking, chromatographic columns cannot be back washed. But, if the manufacturer specifies the columns can be back washed, the experimenters can remove the impurities through backwashing.

Choose a suitable mobile phase. The suitable mobile phase is chosen to avoid the destruction of the stationary phase. Sometimes it is a better way to install a pre-column which has the same substrate and little impact on the reaction, where the mobile phase will be pre-reacted before entering the analysis column.

Several Attentions about Using and Maintaining Chromatographic Columns

Product Highlights & Core Technique of Filter Membranes

Usually, there are two essential properties that end users are the most—extractability of the impurities and advantages of microporous polymer membranes.

Extractability of The Impurities

Scientific laboratories mostly apply the membrane product to filter samples, mobile phase, and chemical solvents. Hence, once the filter membranes itself dissolves some impurities during the experiment, the final results informed from customers would be affected seriously.

To conclude, products from Hawach Scientific Co., Ltd have lots of following merits.

First, all filter membranes are imported from Germany or the US so that there are proportioned materials and low contains of impurities. Second, the workshop where production is cut and packaged is highly clean.

Microporous Product Advantages

According to the Standard specification of ISO9001, the quality of Hawach Scientific Co., Ltd production is supervised rigidly and the stability keeps remarkable among article batch numbers.

Besides, with various options of disc filters and breadths, purchasers are able to choose their ideal goods. Similarly, the large majority of filter membranes materials are suitable to lab samples from areas of the world making sure that the filtering process goes orderly as it was expected.

Product Highlights & Core Technique of Filter Membranes

C8 HPLC Columns

C8 HPLC columns are used to isolate many organic compounds, which are one of the reversed phase silica gel columns.

The maintenance of C8 HPLC columns requires organic solvents. Chromatographic grade methanol is recommended and different brands of chromatographic columns should be treated differently. If the chromatographic column is stored after use and will not be used for a long time, it still needs to be saturated when reused.

Warning for using C8 HPLC columns

It is necessary to ensure that the column bed does not dry up, especially in the process of sample injection detection and column washing. Otherwise, the column will dry up and a large number of bubbles will be brought in, and even cause the column bed local collapse or central cracking.

The difference between C8 HPLC columns and C18 HPLC columns

C8 is suitable for the analysis of substances with slightly stronger polarity in weakly polar substances, and C18 is suitable for the analysis of substances with weaker polarity in weakly polar substances, but the difference is not particularly obvious. Generally, substances that can be analyzed by C8 HPLC columns can also be separated by C18.

C8 HPLC Columns

How to Use the Pipette?

1. Capacity setting
For the adjustable pipette, it is usually operated in the range of 10% to 100%. The optimal pipetting capacity is in the range of 35% to 100%. At this time, it is less affected by the operation technique and can better protect the pipetting. Accuracy and precision. For example, to remove 600 uL of liquid, it is best to choose a 100 to 1000 uL adjustable pipette instead of 500 to 5000 uL.

2. Install the tip
Installation method: Insert the lower end of the pipette vertically into the tip, turn it left and right, and tighten it.

Be careful not to use excessive force, otherwise, the internal components will be loose, and even the knob of the adjustment scale will be stuck or the pipette sleeve will be bent.

3. Rinse the tip
When an organic solvent or a highly volatile liquid is removed, a volatile gas forms a negative pressure in the sleeve chamber, causing leakage. Rinse the pipette tip 4 to 6 times to make the gas in the sleeve room saturated, and the negative pressure disappears automatically, which can effectively prevent liquid leakage. However, do not rinse the tip when the sample temperature is very high or low.

4. Aspirate
There are two ways to aspirate: positive aspiration, reverse aspiration.
Positive aspiration refers to the normal method of aspiration. Press the button to the first step to release the solution and release the button. Press the first gear first, then press most of the liquid, then press the second gear to discharge the remaining liquid.

Reverse aspiration refers to pressing the button directly to the second gear and then releasing it so that more liquid will be inhaled. Just press the first gear when the liquid is discharged. The multi-inhalation liquid can compensate for the surface adsorption inside the tip. The reverse aspiration is generally used in combination with the pre-flushing and aspirating method and is suitable for viscous liquids, volatile liquids and small volume pipetting.

5. Draining
There are three ways of draining: draining along the inner wall, draining above the liquid level, and draining below the liquid level. The usual “draining along the inner wall” steps can be seen below:

(1) Stick the tip of the nozzle to the inner wall of the container and keep it inclined from 10° to 40°, and smoothly press the button to the first gear. After a slight stop, press the second gear to discharge the remaining liquid; when discharging dense or viscous liquid, stay The time is a little longer.
(2) Press the button and lift the pipette to lift the tip of the container out of the container wall.
(3) Release the button.

6. Remove the tip
The tip can be removed by pressing the tip ejector with a little force. If the tip is installed too tightly, it can be removed by hand. Discard the tip into a suitable waste collector.

How to Use the Pipette?

QuEChERS for Agricultural Residue Pretreatment

The average sample addition recovery rate of QuEChERS method is higher than 85%, with fewer impurities interfering with the detection of the target substance, a small amount of solvent, simple and fast operation, which will be the preferred pretreatment method for routine detection of pesticide residues in small laboratories around the world.

In addition to the QuEChERS method, currently commonly used methods for the pretreatment of agricultural residues in food include:

1. Solid phase extraction (SPE)；
2. Solid phase microextraction (SPME)；
3. Gel permeation chromatography (GPC)；
4. Supercritical fluid extraction (SFE)；
5. Matrix solid-phase dispersion extraction (MSPDE)；
6. Accelerate solvent extraction (ASE).

Improvement

Some improvements to the QuEChERS method are intended to ensure the effective extraction of ph-sensitive compounds (such as phenoxycarboxylic acids), minimize the degradation of unstable compounds (such as alkaline or acidic unstable pesticides), and expand the range of food substrate types that can be used with QuEChERS method.

The application prospect

Hawach QuEChERS method can be applied to the extraction and purification of various molecular structures and polar pesticide residues. The method is simple, rapid, accurate and sensitive.

QuEChERS for Agricultural Residue Pretreatment

The Introduction of Bottle-top Dispensers

The bottle-top dispenser, also known as the bottle-top pipette, is an instrument for accurately measuring liquid medicine. It is widely used in the biological and chemical fields, as well as in clinical medicine, industrial and commercial laboratories.

Bottle-top dispenser material

Generally, the main materials of the bottle-top dispensers are as follows: optical glass, Al2O3, ETFE, PFA, FEP, PTFE, platinum-rhodium alloy, PP, and the like.

Range of Application

The bottle-top dispensers are mainly used for general acid and alkali, low concentration of strong acid and alkali, salt, and other liquids should be used with caution. The next thing to say is the banned solution, such as:

(1) The liquid that reacts with ETFE, FEP, PEA, PTFE, Al2O3: sodium azide
(2) The liquid that corrodes optical glass: hydrofluoric acid (HF)
(3) Liquid (H2O2) which acts as a catalytic decomposition of platinum-rhodium alloy
(4) Nicotinic acid, trifluoroacetic acid, tetrahydrofuran
(5) Explosive liquid: carbon disulfide
(6) Suspension: carbonaceous solution
(7) Limiting solution: concentrated hydrochloric acid, nitric acid, chlorinated hydrocarbons and fluorinated hydrocarbons and liquids which can form precipitates can cause the piston to stick or cause clogging (such as crystallization solution or concentrated alkaline solution).

The Introduction of Bottle-top Dispensers

Different Applications of Qualitative and Quantitative Filter Paper

The biggest feature of filter paper is paper with good filtration performance. At present, the filter papers produced in China mainly include quantitative analysis filter paper, qualitative analysis filter paper and chromatographic qualitative analysis filter paper.

Quantitative filter papers are cellulose filter papers, as are qualitative filter papers. They are not suitable for other types of filter paper, such as glass microfiber filter paper.

1. The general qualitative filter for filtering solution, chloride, sulfate and so do not need the qualitative test of numerical calculation; and quantitative filter paper is used for numerical calculation of the precision filter.

Qualitative analysis filter paper generally has more residual ash, which is only used for general qualitative analysis and for filtering precipitation or suspension in solution but can not be used for quality analysis.

The types and specifications of qualitative analysis filter paper are basically the same as those of quantitative analysis filter paper, indicating fast, medium and slow speed, but printing fast, medium and slow words.

2.Quantitative analysis filter paper in the manufacturing process, the pulp is treated with hydrochloric acid and hydrofluoric acid and washed with distilled water. Most of the impurities in the paper fibers are removed, so the residual ash after burning is very small, which has little effect on the analysis results. It is suitable for precise quantitative analysis.

Different Applications of Qualitative and Quantitative Filter Paper

How to Prevent the HPLC Column Failure

The improper use of chromatographic columns will make the columns decrease or lose effectiveness.
Generally speaking, the columns always have problems at the end of them. If we can install a short column with the same stationary phase as the analysis column in front of analysis column, which is about five to thirty millimeter, the column will have a longer lifetime. Although the effectiveness with a short protective column is less, the final result is worthwhile.
The chromatographic columns’ lifetime usually can reach two years and more when used correctly. One kind of the columns that are based on silica gel only can be used in pH values ranging from two to nine. Some adsorptive substances will be retained on the top of the column, especially some colored substances after used for a long time. For the new columns, the filler at the top of the columns may decrease and collapse, which reduce the column efficiency. And under this circumstance, the experimenters can restore the efficiency of the columns through adding fillers. 
It is better to rinse the columns with eluent with strong eluting power after each work. When hydrochloric acid buffer solution is used as mobile phase, salt-free mobile phase is used to rinse. The compounds containing halogen family may corrode stainless pipes. It is inappropriate to be exposed to them for a long time.
How to Prevent the HPLC Column Failure

Summary of Hawach Filter Paper

Hawach Scientific is a modern enterprise contains well integration of R&D, production, sales, and after-sales services.

We have a sales team for filter paper, after more than 16 years promotion, the high praise from the market for our quality and services, filter papers have various size and functions, here are our summary for filter papers:

1. Lab filter paper: Qualitative filter paper and Quantitative filter paper, we have the full size of filter paper for you choose, accept OEM and customized size. Right now, Hawach Qualitative filter paper we can customize max diameter is 750mm, Quantitative filter paper max diameter is 300mm;
2. Asphalt filter paper: Special filter paper for Asphalt filtration, 400mm diameter, 350g/m2, 50pcs/pk, we also can accept OEM and customized size;
3. Sugar filter paper: Special filter paper for Sugar, our regular size is 185mm, we also can accept OEM and customized size;
4. Wine filter paper: Special filter paper for Wine, 80g/m2, Medium speed, 7-10um, have very good performance for wine, we also can accept OEM and customized size;
5. Hawach Filter paper has a round disc, sheet square, Roll type.

Hope the above contents are clear enough for you to understand our filter papers, any questions or help you need, please don’t hesitate to contact us.

Thank you and have a nice day.

Summary of Hawach Filter Paper