Sample Vials Caps

A sample vials cap (or gasket), made of paper, rubber, corkwood, metal, glass fiber or plastic polymer, is placed between the two planes to strengthen the seal and prevent fluid leakage. Machined surfaces cannot be perfect so use caps to fill in irregularities. Asbestos may be present in caps for specific applications.

The function of the sample vials cap

1. Prevent damage to objects caused by the use of spring pads in the process of removing screws.
2. Increase the contact area.
3. It can be used in some special situations.
4. Increase friction.

The choice of sample vials caps material mainly depends on the following three factors: temperature, pressure, and media. According to its material and structural characteristics, caps can be divided into non-metallic caps, metallic caps, metal-non-metallic composite caps, each category of which also can be subdivided into a number of types.

Sealing sample vials cap installation requirements

1. The sealing surface shall be cleaned.
2. When the sealing cap is pressed, it is best to use a torque wrench.
3. When installing the sealing caps, tighten nuts in sequence.
4. The pre-tightening force of the sealing cap shall not exceed the design specification.

The Definition and Application of Capsule Filter

The structure of capsule filtration components is compact, which is quite convenient to use. More than that, its design could meet the highest standard of reliability, security and user convenience.

In order to satisfy numerous needs, it combines all other kinds of the filtration medium, pore size rating, and superficial area. Every capsule filter is made of compact and folded filtration components, which is sealed in a solid and disposal Polyacrylic cover.

According to the unique and advanced craft, filtration components and the cover are thermally bonded into an independent unit. It is the permanently sealed integrity structure which provides the most powerful guarantee for the filtration capability, reliability and security in the widespread fluid and applications.

Capsule filter should provide various size and different kinds of adaptors so that it could easily and quickly connect to the most filtration system.

Capsule filter could satisfy key requirements to contamination in many fields, such as pharmacy, biology, biological processing, electron, chemical industry, beverage, cosmetics and so on. In addition, it is used for controlling the particles and microbial pollution in liquid and gas, which provides reliability and convenience in testing.

Use of Standard Diaphragm Vacuum Pumps

When selecting the customer, it is recommended to first confirm the vacuum and pumping speed required for the experiment, or you can choose according to the application. The main uses of Standard Diaphragm Vacuum Pumps include the following:

1. Vacuum drying oven: It is suitable for vacuum drying oven with volume below 50 liters. The standard vacuum gauge is easy to observe the vacuum during use. The regulating valve can be easily released after pumping. Compared with the general oil pump and dry box, the most significant advantage is that there is no problem with oil backflow, oil change, and oil mist pollution.

2. Vacuum filtration: Compared with general oil-free piston pumps and diaphragm pumps, Standard Diaphragm Vacuum Pumps has the advantage of the higher vacuum, which can significantly increase the filtration speed when actually used in suction filtration. Especially for some customers with high particle content, viscous, the slow pumping rate of the ordinary suction pump, and hope to increase filtration speed and work efficiency, it is an excellent choice.

3. Air sampling: used to collect gas and can be discharged from the exhaust port of the tail to collect the gas to be sampled.

The Advantage of Bottle-top Dispensers

For safe, accurate and accurate dispensing of bases, saline solutions, acids, and some organic solvents, bottle-top dispensers are the perfect tool in the lab. Scientists set them directly on most solvent and reagent bottles for faster and easier dispensation.

Bottle-Top dispenser can dispense most of the lab reagents, such as acids, bases, saline solutions. They can dispense many organic solvents as well, such as HCl and HNO3, trifluoroacetic acid (TFA), tetrahydrofuran (THF), and peroxides.

Bottle-top dispensers can deliver accurate, precise volumes while dispensing, And on the advanced digital models, we can find accurate volume settings through a digital display.

Including safety features to reduce the risk of injury from inadvertent dispensing and splashes in the lab, bottle-top dispenser can be attached on reagent bottles to reduce poured reagent transfers. In this way, the laboratory safety is increased. At the same time, the recirculation valve system of the bottle-top dispensers improves conservation and safety of reagent.

The feature of perfect wear and damage resist makes the dispensation always go smooth. They can be disassembled and washed easily as while. With the bottle-top dispenser on your hand, reliable dispensing is at your fingers.

Hawach 7 Steps Help You Choose the Right Filter Paper

1. Product No., for example BIO-1.

2. Pore size and flow rate, The bigger pore size, the quicker flow rate.
Fast: 60-100S/100ML @ 80-120μm
Medium: 100-160 S/100ML@30-50μm
Slow：160-200 S/100ML @ 1-3 μm

But filter paper is different from filter membrane, the pore size cannot be a certain value, these data only for your reference.

3. Ash content: Some filter papers need to be burned out during downstream analysis. Qualitative and quantitative filter papers are distinguished according to the ash value. Hawach Qualitative filter paper ash: <0.1%, Hawach quantitative filter paper <0.007%.

4. Basic weight:
Qualitative filter paper 80+/- 4 g.
Quantitative filter paper 97+/-7 g

5. Particle retention: 98% intercepted particle size, 11μm, 8μm, 2.0μm, Hawach offers more than 5 options.

6. Burst strength: a data to show the durable of the paper.
five options among 120 140,180,200 and 320 mm H2O

7. Dimensions: such as round, square, boat or folded, round diameter(mm) 70,90,10,125,150,180,240,270,300. Square size(mm): 60×60, 41×45.

More tips, just feel free to contact us!

Hawach High-Performance Extraction Thimbles

A more efficient way to extract compounds from solid materials—Soxhlet extraction (also known as sand extraction).

In the laboratory, Soxhlet extractor uses solvent reflux and siphon principle, so that the solid substance is continuously extracted by pure solvent, which saves solvent extraction and works more efficiently.

The first step ground the solid material before extraction to increase the area of solid-liquid contact. The second step places the solid powders in an Extraction Thimble. The third step put them in an extractor, connect its lower end to a round bottom flask which contains the solvent and connect the higher end to a reflux condenser. Now all the preparatory work is completed.

So Soxhlet extractor, extraction thimble, and the solvent are the 3 key factors for Soxhlet extraction.

Hawach offers 2 kinds of options, cellulose extraction thimbles, and glass fiber extraction thimbles.

General Soxhlet extraction, Indoor dustfall, toxic organic substances (phthalic acid), so you can choose cellulose ones.

Operating temperature above 120 °C, strong acid and other substances which cellulose extraction thimbles cannot apply to, so you can choose glass fiber ones.

You can compare price but cannot tell quality only from words and pictures. No worries, Contact us to get samples!
Hawach High-Performance Extraction Thimbles

Three Types of Bottle-top Dispensers

According to the properties of solutions, the bottle-top dispensers are divided into three types.

The first one is the basic one. It is highly applied to the common solutions, such as the non-oxidative but a strong acid/base with a lower concentration, polar organic solvent and the solutions of acid, alkali or salt. H3PO4, HCL, H2SO4, NaOH are frequent here.

The second one is the organic one. It is used for the vast majority of organic solutions and the strong acid with high concentration. Let me list some examples. There are the organic solvents containing fluorine or chlorine, chloroform, peroxide, and some other solvents.

The third one is applicable to HF solutions. The plunger of the bottle-top dispenser is made of pottery and porcelain because HF solution can corrode glass.

The process of moving solutions by the bottle-top dispenser is totally closed, which effectively prevent the solvents’ volatilization, spatter and spill. That is safer than moving solutions by cylinders. We can even transfer the solvents with high density and volatilization in the petrochemical industry.

What’s more, chloroform is usually used as solvents for most plastics. It is often used for experiments in labs. However, it is easy to volatilize and poisonous. Transferring chloroform through the bottle-top dispenser can avoid it because of the closed conditions.

C1 HPLC Columns

C1 HPLC columns are used to analyze the compounds with strong hydrophobicity and separate multifunctional compounds, which use high water content solvent to analyze the compounds with high polarity.

C1 HPLC columns are reversed phase chromatographic column. Reversed phase high performance liquid chromatography is suitable for the separation of non-polar, polar or ionic compounds.

The regeneration of C1 HPLC columns

The regeneration process must pay attention to the change of column pressure at any time. Too high column pressure will easily lead to the deformation and cracking of silica gel and the disordered connection sequence of the polar end of the bonding phase. At the same time, sufficient regeneration time should be ensured.

Sieve plate blockage and column head collapse of C1 HPLC column

The main phenomena include serious increase or instability of column pressure, trailing of the chromatographic peak, broadening of the chromatographic peak, bifurcation of chromatographic peak and convex peak, etc., which need to be removed and elastic recovery treatment.

Special note for C1 HPLC column: if it is not a special case. Other methods are feasible. It is best not to backflush the column and remove the sieve plate.

Structure of HPLC Column

The empty column is assembled from column joints, column tubes and filters.
The HPLC column joints are constructed with a low dead volume. The column joints are threaded assemblies at both ends, with 7/16-inch external threads on one end and 3/16-inch internal threads on the other end (standardized at home and abroad). The 7/16-inch external thread is connected to the 1/4-inch column tube (Φ6.35mm) and placed in the middle for sealing. The 3/16″ internal thread is connected to the 1/16″ (Φ 1.57mm) connecting tube, and a pressure ring is placed in the middle for the seal of the column joint. In order to minimize the dead volume outside the column, when installing the column, use a Φ1.57mm connecting tube to insert the hollow screw into the ring, and then tighten the hollow screw. The pressure ring is pressed and deformed by the hollow screw and then hung on the connecting pipe (the length of the pipe exposed after the connecting pipe passes through the pressure ring should be strictly controlled to 2.5 mm long or other fixed sizes).

In the column joints at both ends, a stainless steel filter (or strainer) is placed at each end of the HPLC columntube to block the column packing from being washed out of the column by the mobile phase. Each component of the empty column is made of 316# stainless steel, which can withstand the general solvent effect. However, since the chloride-containing solvent is corrosive to it, it should be noted that the solvent and the connecting tube cannot be stored for a long time to avoid corrosion.

Filter Membranes Technology

Overview of The Technology

Under the help of various permeable filter membranes, membrane technology provides engineering strategies to transport selected substances between two different portions.

To speak in a general way, filter membranes technology is utilized in processing
separating gas or fluid streams in a mechanical way.

Applications

Membrane processes do not require heating so that it consumes less energy than traditional thermal separation technology named distillation, sublimation, and crystallization. Due to its purified physical processing ability, both permeate and retentate portions can be involved.

Specifically, cold separation with the membrane is universally applied to the food, biology and pharmaceutical industries. Moreover, membranes make some separations be realized, which is not imaginable with the thermal methods.

Two Basic Models(to distinguish mass transfer)
In currently available filter membranes, there are two transporting approaches occur successively, especially existing in the ultra-filtration.

1.the solution-diffusion model
With the solution-diffusion model, transporting happens merely in diffusive condition.
*Be careful that the demanded component has to be dissolved in advance.

2.the hydrodynamic model
To operate hydrodynamically, transportation is accomplished in a convective environment, which requires smaller pore dimensions than other two isolated components’ diameters.

HPLC Column Silicone Matrix Properties and Scope of Application

Hawach introduced the properties and application range of HPLC column stationary phase in the silica gel matrix.

Silica gel matrix:

Silica gel, weakly acidic, has a strong memory, used to separate non-polar, weakly acidic compounds, oils, etc.;

C18, a silica-based uncapped reversed-phase C18 column with high bond and density, low loss, high recovery, etc.

C8 octyl, the retention of non-polar compounds is weaker than C18;

CN Cyano, a silica-based cyanopropyl column with moderate polarity for reversed phase or normal phase separation, suitable for carbohydrates and cationic compounds;

NH2 amino group, silica-based aminopropyl stationary phase, used for the separation of phenol and phenolic pigments, petroleum hexaphenol, sugars, drugs and metabolites;

PSA-propyl ethylenediamine, a stationary phase similar to NH2, PSA has two amino groups, which is more ion exchangeable than NH2, and PSA can also chelate with metal ions for extracting metal ions;

SAX strong anion exchange, bonded with quaternary ammonium salt functional groups, mainly used for the separation of weak anionic compounds;

COOH carboxyl group, the bonding functional group is a carboxylic acid, used for the separation of quaternary ammonium salts or other strong cations;

PRS propane sulfonic acid, the bonding functional group is a sulfonic acid, used for weak cations, widely used in the analysis of malachite green;

SCX strong cation exchange, bond, and the functional group is benzenesulfonic acid, used for separation of organic base compounds and biological macromolecule desalting.

How do We Process SPE Cartridges?

Here are some options about how do we process SPE cartridges:

1. Vacuum Manifold

Mostly we would process SPE cartridges by using an SPE vacuum manifold together with a vacuum source. So let’s talk about it more specifically here. First, we remove the O-rings from the threaded vacuum attachment stem and place the threaded vacuum attachment stem through the hole in the side of the glass block.

Then we place the black O-ring onto the stem, and follow with the Teflon washer with its uneven side towards the O-ring and screw the valve body onto the stem, after which we tighten the body onto the stem and screw the vacuum gauge.

Last, we slide the bleed valve onto the valve body and follow with the retaining nut and tighten the nut. Following completion of vacuum gauge and valve assembly, the glass block is placed into the corresponding safety tray. The appropriate assembly polypropylene collection rack is then placed and we can install a liquid waste tray between the source and the glass block manifold.

2. Positive Pressure

This technique applies a proper syringe to work with the SPE cartridge connector in the right size. A positive pressure system could also be applied to process multiple cartridges immediately.

3. Vacuum Side-arm Flask

A vacuum side-arm flask, together with a water tap, makes full use of the Venturi effect. We could also apply the standard vacuum source.

Pipette Aspiration Rate and Storage

Hawach introduces pipettes from the pipetting speed of the pipette and precautions during storage.

First, the rate of liquid absorption. It is often seen in the laboratory that in order to “improve efficiency”, the user quickly releases the thumb during aspiration, which causes the liquid to quickly rush into the tip.

As everyone knows, this forces the liquid to form a turbulent state after entering the tip, so that for small and medium-range pipettes, a vapor mist that is invisible to the naked eye will enter the inside of the pipette, for a large-scale pipettes.

You will see the liquid flush directly into the inside of the pipette. The end result is contamination or even corrosion of the piston of the pipette, which is prone to cross-contamination of the sample and has an impact on accuracy.

The Solvent Filter Device

A few days ago, I wrote a summary of the filter membrane. Many customers said that no product had no truth. So what I wrote today is a product that needs to be used in combination with microporous filter membrane – the solvent filter device.

Technical parameters

The solvent filter device also called a solvent filter unit, solvent filter kit, chromatographic solvent filter.T he main components of the solvent filter device are triangle accumulator bottle (1L) sand core filter head, filter cup (300ml), fixed clamp, dust cover, rubber hose, rubber hose linker, and can be equipped with different filter kit and solvent direct extraction adapter.

Main features

The solvent filtration device of the high-quality glass material is with hard mechanical properties, poor resistant to more than 280 ℃ temperature; Smooth appearance and transparent glass with no bubbles ensure a uniform wall thickness.

The solvent filtration device with good pressure resistance and interchangeability can be used for high temperature and high-pressure sterilization.

The size and specification meet international standards and can be matched with foreign brands. International standard size, through the ISO9001 certification, can be matched with a variety of foreign brands; This product also has fast flow, standard grinding mouth, and good sealing performance.

Characteristics of Bottle-Top Dispenser

As an indispensable experimental instrument for laboratory liquid operation, the bottle-top dispenser has the following characteristics.

(1) The setting operation is simple, and the protective gloves can be worn to operate directly in the process of operation. In addition, it has an efficient set locking device, which can avoid the occurrence of unexpected volume changes in the operation process to the greatest extent.
(2) Its performance is stable and the calibration is convenient.
(3) For the large-capacity liquid distributor, it also has the function of micro-adjustment, which can ensure the accuracy of liquid distribution when large amounts of liquid are distributed.
(4) It can achieve a fast volume setting and has a precise calibration design.
(5) It is equipped with a smooth and precise piston, which can slide up and down, making the operation more convenient and comfortable.
(6) Bottle-top dispenser is equipped with a safety cap for drainage pipe, which can avoid contact with reagents. This unique design makes it easy for operators to install or disassemble even when wearing gloves.
(7) The suction tube is transparent and suitable for reagent bottles of various sizes.

Hawach Filter Papers Material

Proper selection of a properly functional filter medium or filter not only ensures the integrity of the sample preparation process, but also facilitates accurate and reliable experimental results, and is more conducive to accelerating the development process, creating benefits and saving costs.

Ash content

The residual ash content of the filter media (such as cotton cellulose qualitative filter paper) after burning at 900 ° C in air. “Ashes” is essential for gravimetric experiments. The smaller the ash content of the filter media, the lower the impurity background, which also contributes to the cleanliness of conventional samples. The essential difference between qualitative filter paper and quantitative filter paper (including ashless filter paper) is the size of the ash value.

Hawach cotton fiber filter paper

Hawach’s qualitative and quantitative filter papers (including ashless filter paper) are made from high-quality cotton cellulose. These cotton fibers are specially treated to ensure that the α-cellulose content is above 98%. The cellulose filter paper is suitable for conventional filtration, particle retention up to 30um, minimum to 2μm, divided into multiple flow rate levels, and a variety of cut-off particle size/flow rate combinations to meet laboratory application needs.

Hawach ashless quantitative filter papers has an unparalleled high purity and is suitable for chemical analysis and specific gravity. This type of filter paper has the smallest metal background. Other cellulose such as lignocellulose, sheepskin fiber, and other metal backgrounds will be slightly higher, and some varieties add wet strength agents in order to increase the strength of the filter paper.

Therefore, when choosing any kind of filter media (not only cellulose filter media), we must not only choose the “chemical compatibility table of the media and the outer casing”, but also must consider the material of the filter media, the purity of the material. How, because it affects the integrity of the physicochemical information of the sample you are analyzing.

Structure of HPLC Column

The empty column is assembled from column joints, column tubes and filters.
The HPLC column joints are constructed with a low dead volume. The column joints are threaded assemblies at both ends, with 7/16-inch external threads on one end and 3/16-inch internal threads on the other end (standardized at home and abroad). The 7/16-inch external thread is connected to the 1/4-inch column tube (Φ6.35mm) and placed in the middle for sealing. The 3/16″ internal thread is connected to the 1/16″ (Φ 1.57mm) connecting tube, and a pressure ring is placed in the middle for the seal of the column joint. In order to minimize the dead volume outside the column, when installing the column, use a Φ1.57mm connecting tube to insert the hollow screw into the ring, and then tighten the hollow screw. The pressure ring is pressed and deformed by the hollow screw and then hung on the connecting pipe (the length of the pipe exposed after the connecting pipe passes through the pressure ring should be strictly controlled to 2.5 mm long or other fixed sizes).

In the column joints at both ends, a stainless steel filter (or strainer) is placed at each end of the HPLC columntube to block the column packing from being washed out of the column by the mobile phase. Each component of the empty column is made of 316# stainless steel, which can withstand the general solvent effect. However, since the chloride-containing solvent is corrosive to it, it should be noted that the solvent and the connecting tube cannot be stored for a long time to avoid corrosion.

Pipette Maintenance Rules

Pipettes are common and necessary laboratory equipment in the laboratory, and the experimenter must be very cautious about their daily use. However, many people will ignore the related maintenance and maintenance of the pipette after use.

Precautions for maintenance:

1. Regularly clean the pipette, soapy water or 60% isopropyl alcohol is an effective way to clean the pipette, then rinse with distilled water, and finally dry naturally.
2. Before high-temperature sterilization, make sure the pipette can adapt to high temperatures.
3. If not used, adjust the range of the pipette to the value scale to keep the spring in a relaxed state to protect the spring.
4. Calibrate by repeating the method of weighing distilled water several times in a 20-25 degree environment.
5. Check for leaks during use. The method is to take the liquid and then hang it vertically for a few seconds to see if the liquid level is falling. If there is liquid leakage, the reasons are as follows:

a) whether the spring piston is normal;
b) whether the gun heads match;
c) If it is a volatile liquid (as is the case with many organic solvents), it may be a problem of saturated vapor pressure.

You can pipette several times and then pipette. For the pipette, not only must it be carefully protected during use, but also should pay attention to some maintenance items of the pipette after use. Only when the use is consistent before and after use can make the pipette have a longer service life and better efficiency.
Pipette Maintenance Rules

Hawach QuEChERS Solutions

Package 1 QuEChERS extracting pesticide residues from plants
Extraction box: 50 ml centrifuge tube + AOAC/EN salt pack
2 kinds of buffer salts: General buffer salt for phase-separation and pH-adjustment;
Anhydrous magnesium sulfate completely separates water in the matrix from the acetonitrile extract.

Package 2 QuEChERS cleaning up the extracted mixture via absorption action
Purification box: 2 ml/15ml Purification tube with the adsorbent (PSA, GCB, C18, anhydrous magnesium sulfate) inside.
PSA can be used to remove polar interferences, such as adsorbed carbohydrates, organic acids, and pigments etc.
GCB adsorbs chlorophyll, mainly for high potency fat and pigment fruits and vegetables, such as eggplant, green vegetables, carrots etc.
C18 removes non-polar interferences, for example, avocado.
Anhydrous magnesium sulfate removes moisture from the substrate and is widely used in various foods.

Package 3 QuEChERS extracting and purifying the pesticide residues.
Extraction tube 1EA + Purification tube 2EA.

Package 4 Prevents local heat dissipation caused by salt agglomeration; makes the pH of the whole system more uniform; thus making the extraction better and saving extraction time.

Ceramic homogenizer 2ml/15ml/50ml three specifications

Easy, straightforward and almost can start without any training. Except for those 4 options, standard adsorbents, salt packs, ceramic homogenizers, etc. can also be customized or purchased separately.

The Solvent Filter Device

A few days ago, I wrote a summary of the filter membrane. Many customers said that no product had no truth. So what I wrote today is a product that needs to be used in combination with microporous filter membrane – the solvent filter device.

Technical parameters

The solvent filter device also called a solvent filter unit, solvent filter kit, chromatographic solvent filter.T he main components of the solvent filter device are triangle accumulator bottle (1L) sand core filter head, filter cup (300ml), fixed clamp, dust cover, rubber hose, rubber hose linker, and can be equipped with different filter kit and solvent direct extraction adapter.

Main features

The solvent filtration device of the high-quality glass material is with hard mechanical properties, poor resistant to more than 280 ℃ temperature; Smooth appearance and transparent glass with no bubbles ensure a uniform wall thickness.

The solvent filtration device with good pressure resistance and interchangeability can be used for high temperature and high-pressure sterilization.

The size and specification meet international standards and can be matched with foreign brands. International standard size, through the ISO9001 certification, can be matched with a variety of foreign brands; This product also has fast flow, standard grinding mouth, and good sealing performance.

Extraction Thimble Installation and Application

Extraction thimbles are a kind of cylinders used for filtering gas medium or liquid medium, which are divided into three categories in accordance with the material: cellulose, glass fiber and quartz fiber.

Cellulose exaction thimbles are mainly used for general Soxhlet extraction and filtering indoor toxic organic matter and dust.

Glass fiber exaction thimbles apply to the condition that is not suitable for cellulose exaction thimbles, such as the temperature higher than 120 ℃, or the strong acid environment.

Quartz fiber exaction thimbles cannot be made in China.

The installation of exaction thimbles

It is divided into vertical hoisting, oblique installation at a specific Angle, flange installation, etc, and the commonly used automatic cleaning methods of which include high-pressure gas pulse back blowing and mechanical vibration.

The application of exaction thimbles

An exaction thimble dust remover has appeared in Japan, some European and American countries as early as the 1970s. In recent years, it is widely used in cement, steel, electric power, food, metallurgy, chemical and other industrial fields with the advantages of large effective filtration area, low-pressure difference, low discharge, small volume, and long service life.

How to Choose the Right Bottle-Top Dispenser?

The bottle-top dispensers are a useful tool to dispense reagents, media, chemicals, and solutions from bottles, containers, and into other vessels. With components of filling tube, piston or pump, discharge valve, and discharge tube, the bottle-top dispenser is a popular chemical method for transferring in many labs.

We can dispense a liquid accurately and precisely in a safe way by using the dispenser. You may concern about the chemical compatibility, viscosity, volume, frequency when selecting the bottle-top dispenser for your lab, and the budget too.

There are some important design features you should consider when you purchase the bottle-top dispensers, such as recirculation valve, autoclavable, and volume setting mechanism.

Recommended by in many labs, the bottle-top dispenser can recirculate the liquid as the scientist primes the dispenser. The feature can lower the cost by less chemical splashing and liquid lost. The fully autoclavable dispensers should be considered If autoclaving is required.

Make sure if the valves of the dispensers need to be loosed before autoclaving. The volume adjustment knob, volume adjustment dial, and electronic with premium dispensers are three designs of volume setting mechanism which is widely used in the lab.

A Brief Introduction to Hawach Qualitative Filter Papers

Qualitative filter papers usually apply to filter at atmospheric pressure, which uses the ability of the material to remove particles to separate the liquid and solid of the sample. It covers most of the laboratory applications, is used commonly for liquid clarification and, sometimes, for qualitative analysis and purification of the deposits.

In the industrial filtration, it is commonly used to separate solids or extract liquids from solution as a filter material, not as chemical analysis filter paper. The Hawach qualitative filter paper has two categories: standard grade products and wet strength grade products. Users can select from either product depending on their requirements.

Standard Grade qualitative filter papers

Standard grade qualitative filter paper is frequently used in conventional filtration. There are several models of its different particle retentions and filtration speeds.

Usually, the slow filtration speed ones which have stronger separation ability by high adsorption are suited for the chemical analysis. In industrial, medium particle retention, medium filtration Speed models are especially suits to the analysis. Besides, the fast filter paper is thicker and has a higher load which can be used for filtering culture media and colloid substances.

C18 HPLC Columns

C18 HPLC columns are the reversed phase columns, high purity silica gel skeleton, single function high-density bonding, excellent peak shape, extremely high stability, suitable for the separation and analysis of amphoteric and acidic compounds.

Application of C18 HPLC column

1. Good separation of neutral, acidic, amphoteric and partial alkaline compounds;
2. Especially suitable for the analysis of acidic and amphoteric small molecular compounds;
3. Can be used to maintain the stability of the compound;
4. Can be used to change the separation selectivity.

The installation and use of C18 HPLC columns

Rotate the column heads at both ends of the column and connect them to the instrument according to the direction of fluid flow on the label of the column. When the column is not in use, screw on both ends of the column.

Sample and mobile phase

To avoid blockage of C18 HPLC columns, the sample and mobile phase are filtered by a filter membrane before use. The mobile phase is a mixture of the organic phase and water phase, such as methanol-water, acetonitrile-water.

It is best to install a protective column to prevent impurities and protect C18 HPLC column.

Knowledge of Filter Papers

Filter paper has excellent filtration property and strong absorption performance on liquid. Scientific workers use filter paper as a kind of media in analytical laboratories to separate solution from solid. Currently, there are mainly three kinds of filter papers which can be purchased in domestic market: quantitative filter papers, qualitative filter papers, and chromatography qualitative filter paper.

During the manufacturing processes of quantitative filter paper, the pulp is processed by hydrochloric acid and hydrofluoric acid. After washed by distilled water, most of the impurities inside the paper fiber can be filtered so that the filter paper is fit for precise quantitative analysis.

Types of Filter Paper

Domestic produced quantitative analysis filter paper falls into three types: fast speed, medium speed, and low speed. They are marked with a blue belt (fast speed), white belt (medium speed) and red belt (low speed) respectively. Commonly, there are two shapes of filter papers you find in the market: round and square. The former one is always with the diameter of 9 cm to 18 cm, while the latter one is with the dimension of 60 cm x 60cm and 30 cm x 30 cm.

General Notes of Using Filter Paper

1. Make use of natural filtration to separate the liquid from solid.
2. Considering of low mechanical strength and tenacity of filter paper, make sure of using less suction filtration.
3. It is better not to filter hot concentrated sulfuric acid or hot concentrated nitric acid through filter paper.

GF Filter Membrane

A GF filter membrane is made of 100% borosilicate glass fiber, with capillarity fiber structure, which can absorb more water than the same fiber filter paper, with fast flow rate, high bearing capacity, high-temperature resistance, and can very well retain fine particles.

A GF filter membrane has the characteristics of non-hygroscopicity and biological inertness and is resistant to chemical corrosion of most solvents and reagents except hydrofluoric acid and high concentration of the acid-base solution.

Application
1. Used for daily air pollution monitoring;
2. The collection of high-efficiency fine particles;
3. Used for water pollution analysis;
4. Dust collection in the air.

A GF filter membrane without binder is usually used for filtering fine particles, which is divided into six grades: A, B, C, D, F, and H.

Binder can enhance the mechanical strength of a GF filter membrane that is mainly used to filter coarse particles (such as macromolecular substances and dust). In order to avoid chemical reactions with the filtered substances, the glass fiber with the inorganic binder is selected when filtering organic substances and the glass fiber with an organic binder is selected when filtering inorganic substances. The most common grades are 6, 8, 9, and 10.