The Importance Of Sample Vial

 If the tolerance is not strictly controlled, the marked size and wall weight of the autosampler vial may be different, which will affect the sample vial in the vial. Long it is very important for small samples.

Our strict tolerance control runs through during the entire manufacturing process, from the initial design to the final photoelectric scanning inspection process, the accuracy of the specifications of each sample bottle and bottle cap is ensured.

The integrity, cleanliness, and uniformity of the sample vial are essential for today’s demanding applications. All sample vials are manufactured in a clean environment, and the unique packaging ensures cleanness and safety during transportation.

The inconsistent thickness of the bottom of the sample vial will lead to inconsistent sample extraction and damage the injection needle. Stopping the autosampler sequence will result in wrong grabbing or dropping of sample vials and loss of precious samples.

Failure to detect a leak in the seal can result in sample loss, volatilization, or even contamination of the sample. Septa that is displaced or incorrectly positioned can cause sample loss and sample contamination.

In the face of sample bottle selection, the following three elements have to be carefully considered!

Gasket
PTFE/silica gel: Has excellent resealing characteristics. Before piercing, it has the chemical resistance of PTFE, and after piercing, the septum will have the chemical compatibility of silica gel.

PTFE/silicone (pre-notch): Provides good ventilation to prevent the formation of a vacuum in the sample vial, thereby achieving excellent sampling reproducibility. Eliminate the clogging of the bottom needle after sampling. Good resealing ability. Recommended for multiple injections.

Bottle cap
Screw cap: universal bottle cap with good sealing effect. Withstand the septum mechanically, no other tools are needed.

Jaw cover: Aluminum jaws, good sealing effect, prevent sample evaporation. High temperature experiment environment, more resistant to high temperature. It needs to be used with the capping device. The sealing effect of the bayonet cap is not as good as the screw cap and the crimp cap.

The push-type bayonet cap is very suitable for storing powder samples, not suitable for transporting liquids. If the fit of the bottle cap is very tight, it is difficult to close the bottle cap and may break; if it is too loose, the sealing effect will be poor.

Bottle body
Glass-general-purpose and acid-resistant type; brown bottles-for light-sensitive samples; silanization/deactivation-for samples that easily adhere to the wall of glass bottles and trace analysis; polypropylene-for alcohol Class samples or water-soluble solvents; micro-lined tube-for very small injection volume; high yield-for limited sample volume.

Hawach Advanced Syringe Filters And Sterile Syringe Filters

 Throughout entire syringe filters production process, Hawach always maintains the strictest levels of quality control. You will find Hawach syringe filters will never leak sample solvent, due to its medical-grade pure polypropylene housing welded with high quality membrane. Hawach have three series of syringe filters: the advanced syringe filters, the disposable syringe filters, and the sterile syringe filters.

Hawach offers syringe filters with a wide variety of membranes and pore sizes, the syringe filters will help you get the high flow rates and maximum sample loading capacities. The full visual control is available as all the Hawach filters have transparent housings.and the different colors code our disposable syringe filters for easy identification, which can make your job easier. Now,Hawach mainly introduce the advanced syringe filters and the sterile syringe filters.

As we all know, before column chromatography, using the advanced syringe filters is the fastest and simplest method for small volume filtration.

Many of the advanced syringe filters are compatible with all sorts of aqueous solution, solvent and chemical reagent. Also, the advanced syringe filters have the advantages of fast filtering speed, high purity and very suitable for analysis and operation of standard substance.

Meanwhile, the advanced syringe filters are not only suitable for gas filtration, but also can be applied for the filtration of corrosive solution without producing any extract.

Moreover, filtration sterilization is the fastest way to remove bacteria from the liquid and will cause the least effects to the solution composition. Normally, the advanced syringe filters can provide the aperture range from 0.1 μm to 5 μm. Also, the products have the features of high flow rate and low adsorption rate, and the effective filtration area can reach 6.2 c㎡.

In general, the advanced syringe filters are one of the products with the largest filtration yield and the fastest filtration speed. At the same time, most of the products can be sterilized through ethylene oxide or gamma radiation.

Clarification application of sterile syringe filter

Sterile syringe filter does not need to change mold and clean filter, which greatly saves complex and time-consuming preparation work, and is suitable for sample pre-filtration, clarification, sterilization filtration and other applications.

The sterile syringe filter is frequently used in conjunction with a disposable syringe, which has become a fast and convenient filter processing device for small volume samples with various filter diameter such as 4mm, 13 mm, 25mm, 33mm and 50 mm. Moreover, the sterile syringe filter can make full use of the pressure difference provided by the vacuum pump to handle different samples.

Property differentiation of various materials

Hawach sterile syringe filters of different materials have the properties of phase differentiation, the mixed fiber membrane has good hydrophilicity, strong chemical compatibility, low protein absorption and adsorption, and is suitable for sterilization filtration of medium and containing protein preparations; in contrast, nylon membrane also has better chemical compatibility and can be used for sterilization and filtration of biological products, culture medium and solution under the condition of pH value 1-12.

Furthermore, the low protein adsorption, high flow rate and a wide range of pH values of sterile syringe filter make it suitable for pre-filtration and clarification of buffer solution, liquid culture medium.

Hawach Advanced Syringe Filters And Sterile Syringe Filters

5-10L Short Path Distillation

Turnkey short path distillation is symbolized by its unique separation principle of different free paths of motion, rather than by different boiling points. Because the path light molecular vapor takes from the heating surface to the condenser tube is very short, the equipment using this working principle is called short path distillation equipment.

Hawach has various short path distillation for sale. 2L and smaller volume turnkey short path distillation is for the mini or small trial experiment;

 

5L short path distillation and 10L short path distillation kit

 

are medium-sized short path distillation equipment; 20L-50L or bigger volume is big sized

 

short path distillation for sale

 

.

Different from the structure of the 2L short path distillation kit, the receiving flask of 5L short path distillation and

 

10L short path distillation kit

 

is single-headed, because bigger volume glass parts are fragile, especially with weight pressure.

The development of turnkey short path distillation equipment adopts the working principle of molecular distillation, but with several difference listed as follows:

1. The vacuum degree is lower than that of molecular distillation;
2. Magnetic stirring replace thin-film scraper, which is much less effective than that of molecular distillation;
3. The evenness and efficiency of the heating mantle is much worse than jacketed conduction oil in molecular distillation;
4. Distance between the heating mantle and condensation tube of short path distillation for sale is farther than that of molecular distillation.
5. The efficiency of the outer small condensation tube is much lower than that of big inner coil condenser in molecular distillation;
6. Short path distillation is mainly for pre-treatment of molecular distillation or small amount separation experiment, while molecular distillation can be used in a pilot trial to medium production.

5-10L Short Path Distillation

Classification Of Stainless Steel Molecular Distillation

 1. Falling film molecular still

For the early form, the structure is simple, but due to the thickness of the liquid film, the efficiency is poor, the world is rarely used. The device USES gravity to make the material on the evaporation surface fall into a liquid film. When the material is heated, the evaporator condenses on the opposite side of the condensing surface. Falling film device for the early form, simple structure, on the evaporation surface of the formation of a thick liquid film, poor efficiency, now countries rarely used.

2. Scraping membrane molecular distillation device
In China, scraping membrane molecular distillation equipment and process application were developed in the late 1980s. The liquid film formed by the device is thin and the separation efficiency is high, but the structure is more complex than that of falling film. It takes the method of gravity to make the material on the evaporation surface into a liquid film falling down, but in order to make the liquid film on the evaporation surface thin and evenly distributed, a rotary scraper made of hard carbon or Teflon is set in the distiller.

The scraper can not only make the lower liquid layer be stirred fully but also accelerate the renewal of the liquid layer on the evaporation surface, thus strengthening the heat transfer and mass transfer process of the material. Its advantage is: the liquid film thickness is small, and along with the evaporation surface flow; The distillation material has a short residence time at the operating temperature and a low risk of thermal decomposition. The distillation process can be carried out continuously with a large production capacity.

3. Scraper molecular distillation unit (Wiped-Film Molecular Still)
Scraper technology (Wiped Film Style) USES a Smith 45 ° diagonal chute type scraper, the chute would lead to the downward movement of wall material around the distiller, through controllable scraper rotation will be able to provide a high level of thin-film hybrid, make the material produces tiny active effective movement, thus to achieve the shortest and controllable material residence time, and controllable film thickness, thus to achieve the best heat conduction, the mass transport, and separation efficiency.

The key outstanding advantages of this process are short feed liquid retention time, sufficient cooling by virtue of high vacuum performance, optimal mixing efficiency, and optimal material and heat transfer. The result of this efficient thermal separation technique is minimal product degradation and maximum product quality.

4. Centrifugal molecular distillation unit
Centrifugal molecular distillation unit centrifugal force film, thin film, high evaporation efficiency. But the structure is complex, manufacturing and operation are difficult. The device sends the material to the center of the rotating disc at high speed and forms a thin film on the rotating surface. At the same time, it is heated and evaporated to condense with the opposite condensing surface. The device is an ideal molecular distillation device at present. However, compared with the other two devices, the high-speed rotary disk is required and high vacuum sealing technology is required.

Compared with conventional distillation, molecular distillation has the following characteristics:

1. Ordinary distillation is separated at boiling temperature, while molecular distillation can be separated at any temperature as long as there is a sufficient temperature difference between the hot and cold sides. Therefore, the operating temperature of the molecular distillation is much lower than the boiling point of the material.

2. Common distillation has bubbling and boiling phenomenon, while molecular distillation is the free evaporation on the surface of the liquid film, the operating pressure is very low, generally 0.1-1pa, the heating time is very short, generally only 10 seconds to dozens of seconds.

3. The evaporation and condensation of ordinary distillation are reversible processes, and the liquid and gas phases are in dynamic phase equilibrium. In the process of molecular distillation, the molecules escaping from the heating surface directly fly to the condensing surface, and theoretically there is no possibility of returning to the heating surface. Therefore, there is no material that is difficult to be separated in molecular distillation.

Classification Of Stainless Steel Molecular Distillation

Frequently Asked Questions When Using Adjustable Bottle-Top Dispenser

 HAWACH has summarized some FAQs for you to solve your possible problems as soon as possible.

Q1: How to use the lab adjustable bottle-top dispenser?
1. Insert the liquid inlet pipe and tighten the nut.
2. Insert the drain tube and tighten it.
3. Open the cap and place it under the drain tube.
4. Adjust the dispensing volume from zero to the corresponding value through the rotating scale.
5. Exhaust process: Make sure that the cover of the drainpipe is open, lift the piston for a certain distance, then press it down, repeat this step 1-2 times, and stop when the bubbles are completely eliminated through the observation window.
6. After exhausting, start preparing for liquid dispensing. (Note: If the exhaust has not been completely exhausted, please check whether the suction pipe or other valves are installed correctly.)
7. Adjust the dispensing volume from zero to the corresponding value through the rotating scale.
8. After use, first, press the piston to the bottom, and then adjust the knob to zero scales to lock the bottle dispenser.
9. Process: Lift the piston steadily to a higher place, and then press it to the bottom steadily, thus completing a dispensing process.

Q2: After autoclaving HAWACH bottle-top dispenser, it leaks. What’s happening?
The housing has a large amount of surface area.
Some condensation may collect as droplets just below the housing, on top of the valve block, if it is not given sufficient drying time in the autoclave.

Q3: What precautions should take when dispensing scintillation fluid?
Many scintillation fluids precipitate in the presence of water. These precipitates can impair the function of the HAWACH bottle-top dispenser. Please make sure the bottle-top dispenser is completely dry before use. Additionally, in humid climates, it may be necessary to use a drying tube to keep atmospheric moisture from contaminating your scintillation fluid.

Q4: What is the function of the recirculation valve?
The recirculation valve allows you to prime the lab adjustable bottle-top dispenser without wasting any of your chemicals. Before the first use, or after sitting for a period of time, the HAWACH bottle-top dispenser needs to be primed to remove air bubbles. With the recirculation valve, we will not waste any chemicals during the detonation process. If there is no recirculation valve, the initial initiator will be discarded.

Q5: What are the safety instructions for using HAWACH bottle-top dispenser?
1. Read and understand all the details in the user Manual before use.
2. Use protective clothing, eye protection glasses, and gloves while working with hazardous liquids.
3. Do not dispense inflammable media into plastic vessels which generates a static charge.
4. It is not suitable for concentrated  (Hydrochloric  Acid,  Fluorinated  Hydrocarbons,  Saline  Solutions,  Nitric Acid), highly concentrated alkaline solution and crystallizing solution, the liquids attacking  FEP,  PFA,  PTFE,  Borosilicate glass, organic solvents, Trifluoroacetic Acid, explosive liquids, fuming acids, Tetrahydrofuran, suspension (e.g. of charcoal) as solid particles.
5. Handle the dispenser carefully in case of an accident caused by it.
6. The nozzle should always point away from the user while dispensing. Avoid splashes.
7. Always use suitable vessels for dispensing liquids.
8. Never push down the piston while the nozzle cap is on.
9. To clean the discharge tube regularly is recommended.
10. Please do not give excess pressure while aspirating or dispensing. The glass tube may break inside. Please follow the troubleshooting guide if you find any difficulty in moving the piston up and down.
11. Please use original accessories to avoid any kind of accidents.

Q6: How to clean the bottle-top dispenser?
In order to ensure the lab adjustable bottle-top dispenser has a long service life, some maintenance and cleaning can be done in the following situations: the pipetting piston is not flexible; dispense some restrictive solutions (such as high concentration salt solution and high concentration of alkaline solution); before replacing the dispensing reagent; before sterilizing the bottle-top dispenser; replacing the pipes of the bottle-top dispenser (suction tube, return tube and dispensing tube); before long-term storage.
1. Set the scale dial to the zero position, and cover the nozzle of the dispensing tube;
2. Place the dispenser and reagent bottle in an appropriate cleaning container, and then set the scale dial to the maximum dispensing volume;
3. Rotate and remove the bottle dispenser from the reagent bottle (wear gloves to operate);
4. Place the dispensing tube on the reagent bottle mouth, and at the same time remove the dispensing tube cap and slide it back to a fixed position;
5. Move the piston handle up and down (make sure the arrow of the safety valve points to the dispensing tube) to remove the remaining solution;
6. Put a suitable special cleaning solution in the cleaning container, immerse the suction tube in it, and repeat the suction and discharge several times;
7. After repeated pipetting and cleaning with an appropriate solution (such as distilled water or acetone) for many times, take out and drain the remaining solution in the bottle dispenser;
8. Remove the suction tube, return tube, and dispensing tube from the bottle dispenser and clean them separately.

Frequently Asked Questions When Using Adjustable Bottle-Top Dispenser

Surface Modification/Bonding Phase Of FLASH Purification Column Stationary Phase

 By modifying the matrix or bonding different groups, different separation types of stationary phases are formed, usually including normal phase, reversed-phase, ion exchange, SEC, chiral, and other stationary phases.

The chromatographic mode in which the polarity of the modified groups on the matrix is ​​greater than the polarity of the mobile phase is called normal phase chromatography, which relies on the different polarity of the sample to distribute between the stationary phase and the mobile phase to achieve separation. In this separation mode, the sample is eluted from the purification column in order from weak to strong polarity.

Commonly used normal phase stationary phases include unmodified silica gel; diol-based, amino, cyano-based, and other silica-based stationary phases; alumina, etc. The normal phase silica gel stationary phase is mainly used in the preliminary purification of synthetic non-polar or medium-polar intermediates. The conventional flow system is n-hexane/ethyl acetate, dichloromethane/methanol, etc.

Its advantages are simple purification and simple sample post-processing; its disadvantages are low separation performance (compared with reversed-phase immobilization), poor reproducibility, and strong adsorption and even irreversible adsorption of certain substances. In addition, some polar groups (diol groups, amino groups, cyano groups, etc.) bonded normal phase stationary phases are often used in reversed phase conditions. For polar compounds that are not strongly retained in reversed phase stationary phases such as C18, they can Obtain a good separation and purification effect.
Alumina stationary phase is divided into three types: acidic, neutral, and basic. Acidic alumina is generally pretreated with acidic solvents. It has weak cationic properties. It is easier to remain neutral and negatively charged substances on the surface, and cannot retain positively charged substances. It is mainly used in acid pigments, aldehydes, and acids.

Compound separation and purification. Alkaline alumina is usually pretreated with an alkaline solution. It has anionic characteristics and cation exchange function. It has a strong adsorption effect on polar cation samples. It is mainly used for the separation and purification of alkaline pigments, alkaloids, and other alkaline substances. Neutral alumina is not sensitive to the acidity and alkalinity of the sample and is mainly used for acid-base unstable compounds such as glycosides, aldehydes, and esters.

The chromatographic mode in which the polarity of the modified groups on the matrix is ​​less than the polarity of the mobile phase is called reversed-phase chromatography. In this separation mode, the order in which the samples are eluted is exactly the opposite of the normal phase mode: To Ruo was eluted in turn. Most of the reversed-phase stationary phases are based on silica gel matrix bonded with different bonded phases such as C18, C8, C4, C1, phenyl, and other stationary phases. They are widely used in the purification and purification of natural products, peptides, and proteins, and have excellent separation effects. , Good reproducibility, and long service life.

Ion exchange chromatography is a separation mode through the interaction between the surface ion charges of the sample molecules and the surface ion charges of the chromatography packing. The surface of the stationary phase is positively charged, and those that retain anions are called anion-exchange fillers; the surface of the stationary phase is negatively charged, and those that retain cations are called cation exchange fillers. In addition, they are classified as strong ions according to the strength of the ion binding state on the filler surface. Exchange packing and weak ion exchange packing.

The common surface groups of cation exchange fillers are sulfonic acid groups (strong cation exchange), phosphoric acid groups, carboxylic acid groups, and phenolic hydroxyl groups; the common surface groups of anion exchange fillers are primary amino groups, secondary amino groups, tertiary amino groups, and quaternary Amine group (strong anion exchange packing). When ion exchange packing is used in preparation and purification, the resin is usually used as the matrix, and there are more silica matrix and non-porous gels in analytical applications due to pressure and resolution considerations.

A chiral stationary phase is a stationary phase in which derivatives such as polysaccharides, cyclodextrins, and proteins are bonded or coated on a substrate such as silica gel, and chiral recognition and resolution of chiral substances are performed to achieve the purpose of separation and purification.

Since chiral stationary phases are very expensive, in order to protect the stationary phase as much as possible, the chemical purity of the sample is generally required. Usually, the sample is initially purified to improve the chemical purity and remove impurities that are likely to damage or adsorb the stationary phase.

Surface Modification/Bonding Phase Of FLASH Purification Column Stationary Phase

How to Select the Vacuum Filtration or Gravity Filtration？

 There are two types of filtration that are widely used in organic chemistry labs, one is called gravity filtration which is the traditional form of filtration forced by gravity. It’s easy to set, but might come out with poor results in low speed sometimes, and the other one is vacuum filtration. It pushes material through the filter in the Buchner funnel by using a pump that can generate. Both of them can remove solid impurities from an organic solution or isolate an organic solid.

Selecting the right filtration method depends on the nature of the experimental situation. Here are some tips you should think about.

As the method of removing solid impurities such as a drying agent, an undesired side product, or a kind of reactant leftover, gravity filtration can be used to collect the solid from an organic liquid. Actually, you can find that vacuum filtration can do that too, but much fast then gravity filtration.

Although the vacuum filtration is faster than the gravity one, there is something important you should know when you take the vacuum filter into use. First, the glass filter flask must not have any cracks on the bottom of the sides. Second, you have to make sure that the filter flask and the vacuum trap are clamped tightly, and they will not move during the filtration.

It’s important that the clean filter flask, the vacuum trap, and the tubing are made of thick-walled glassware. The water hoses might collapse during the vacuum process if you use the normal tubing.

Remember, don’t perform a vacuum filtration without a vacuum trap and always keep the trap clean. If there is something sucked in there, you will find that easier to recover it from a clean trap then from a dirty one.

If you want to collect the solid, vacuum filtration might be the best according to its high speed. If what you want to collect is the filtrate, gravity filtration methods are highly recommended.

The gravity filtration will the better choice when you have a large volume to filter. Vacuum filtration is good on the one hand because it’s pretty fast, but on the other hand, the risk of spills will increase and the speed will slow down when you need to empty the flask partway through releasing the pressure and removing the funnel. The vacuum filtration is also preferred if there is only a small amount of solids to be collected or if solid is fine.

How to Select the Vacuum Filtration or Gravity Filtration

Use Options For Extraction Thimble

 When measuring samples, the extraction amount depends not only on the polarity and thickness of the fiber coating but also on the extraction method, the volume of the water sample and the headspace phase, extraction time, stirring conditions, extraction temperature, pH, concentration and analysis of inorganic salts conditions and many other factors are related, so when using this method to analyze samples, the measurement conditions must be strictly controlled to make them exactly the same as when determining the calibration curve. Some of these parameters have been optimized to effectively improve the extraction efficiency.

Selection of glass fiber extraction thimble

The application of fiber technology to extract target compounds can use three extraction methods:
direct immersion extraction;
headspace extraction;
membrane protection extraction, three extraction methods.

Direct immersion extraction is to insert the fiber into the sample, and the analyte migrates directly from the sample matrix to the extracted fiber. It is suitable for the analysis of organic compounds in gas samples and clean water samples, but not suitable for the analysis of organic compounds in the complex sample matrix.

At present, the direct method is used for the extraction of most organic compounds, especially for the poorly volatile compounds in the water sample. The extraction head is in direct contact with the analyte during direct extraction, which is better than the headspace method.

For gas samples, the natural flow of air can make volatile compounds quickly reach equilibrium, but for liquid samples, a stable thin liquid layer will form around the fiber coating, which hinders the diffusion and migration of target compounds to the coating, so some form The stirring is very necessary. The disadvantage of applying the direct extraction method to the determination of liquid samples is that the contact between the fiber and the sample matrix will greatly shorten the service life of the fiber.

Headspace extraction is the process of exposing the fiber to the gas phase above the sealed sample and extracting the analyte that volatilizes into the headspace of the solid or liquid sample. It is suitable for analyzing wastewater, grease, humic acid, and other complex matrix samples and solid samples. Semi-volatile organic compounds. Compared with the direct extraction method, the headspace method has more advantages for volatile substances with larger diffusion coefficients.

Because part of the analyte has entered the headspace phase before extraction; here, the diffusion coefficient of the analyte is 4 orders of magnitude higher than that in the liquid phase. The interface between the gas and liquid phases is continuously updated by mechanical methods to make the analyte more Effectively adsorb to the fiber, so the time required for equilibrium is greatly shortened.

For example, for BTEX in water, the sampling time can be shortened from 5 min for the direct method to 1 min for the headspace method, and the detection limit reaches 10-9. In addition, in the headspace extraction method, the fiber does not directly contact the sample, avoiding the interference of the matrix, and the method’s reproducibility is better than that of the direct method.

As the two most commonly used extraction methods, choosing the headspace method or the direct method has no effect on the sensitivity of the method, but should be determined according to the nature of the target compound. Because for a system composed of liquid and its headspace phase, the number of analytes extracted by the fiber is closely related to the concentration of the compound in the sample, regardless of whether the fiber is in a liquid or a gas, it has nothing to do with the location of the fiber.

Only when the direct method is used to extract extremely volatile compounds, and the system does not have a headspace phase, its sensitivity is different from that of headspace extraction.

Membrane protection extraction is suitable for heavily polluted water samples. The fiber is separated from the sample by a selective membrane. The analyte can be adsorbed to the fiber through the selective membrane, while the high molecular weight compounds in the sample cannot pass through, thereby eliminating matrix interference.

Unlike headspace extraction, membrane protection method can be used for the analysis of non-volatile compounds. However, since the analyte must diffuse through the membrane before it can be adsorbed on the coating, the extraction time is longer. To shorten the extraction time, a thinner membrane can be used and the sample temperature can be increased.

Use Options For Extraction Thimble

4 Cleaning Methods Of Air And Liquid Chromatography Sample Vials

Problems caused by incomplete cleaning

There will be many problems if incomplete cleaning occurs: loss of analyte; chromatographic peaks caused by the action of solvent and septum; mechanical damage to the autosampler; sample degradation; poor repeatability of injections, etc. In short, there will be a deviation of the experimental results because the cleanliness of the chromatographic sample vial does not meet the requirements.

According to the glass instrument washing method, choose the cleaning method based on the degree of pollution. HAWACH introduced four methods to clean the chromatographic sample vials.

Method 1: alcohol cleaning
1. Pour out the test solution in the chromatography sample vial.
2. Immerse all of them in 95% alcohol, dry after ultrasonic washing twice.
3. Pour clean water and wash twice with ultrasound.
4. Pour the washing liquid in the dry bottle and bake at 110 degrees Celsius for 1 to 2 hours. Be careful not to bake at high temperatures.
5. Cool and save.

Method 2: Formaldehyde + ultrasonic cleaning
1. Soak in methanol (chromatographically pure) and ultrasonically clean for 20 minutes, then pour the methanol to dryness.
2. Fill the chromatographic sample vial with water, ultrasonically clean for 20 minutes, and then drain the water.
3. Dry the chromatography sample vial.

Method 3: pure water + ultrasonic + ethanol cleaning
1. Rinse with tap water several times.
2. Place in a beaker poured with pure water and sonicate for 15 minutes.
3. Change the water and sonicate for another 15 minutes.
4. Soak in a beaker filled with absolute ethanol.
5. Then take out and air dry.

4 Cleaning Methods Of Air And Liquid Chromatography Sample Vials

Membrane Material And Performance Characteristics Of Filter Membrane

 In the shape of the thin and round precut disc, membrane filters are a good tool for fast and high-efficient filtration of liquid and gas samples. We can find membrane filters made of different synthetic materials for your application, such as cellulose acetate, cellulose nitrate(collodion), polycarbonate, polypropylene, and polyamide (nylon). With the exception of polycarbonate filters, most other membrane filters contain a 50–85% filtering surface.

When you are selecting the membrane filters, you may find so many options to choose from in the market. How do you know which is the right one for your application? By the way for knowing the nature of your solution to be filtered, The first thing you should pick up is the right membrane material,

If the membrane filter is being used as a vent for a gas stream, the membrane made of Hydrophobic PTFE and Polyester (PETE) is the choice; if you want to collect air particles on the membrane surface,  PTFE, Silver, PP, and glass fiber is perfect. To the liquid solution, if you are interested in particles retained on the membrane surface, Polycarbonate (PCTE) and PETE will be easy for surface retrieval and microscopy. When the filtered fluid is what you need, MCE and Nylon are perfect protein-binding capacity for sterilization, and  Cellulose Acetate, PES, PP, and PVDF have good flow rates as well.

Performance Characteristics of HAWACH Filter Membranes

HAWACH filter membranes are strong with the burst (longitudinal) and tensile (lateral) strength is monitored during the process of production. To produce the high-quality filter membranes, we guarantee to use the high purity reagents and raw materials all the time and handle HAWACH filter membranes in a high graded cleanroom to minimize ambient contamination.

HAWACH filter membranes are the thin membranes with high porosity which provides high surface area for adsorption and binding. With the perfect thermostability, all of HAWACH membranes can be sterilized by autoclaving. Depending on the different membrane polymer, the operating temperature can be up to 180°C with minimal shrinkage.

The Procedures In Where We Use The Membrane Filters

Membrane filtration is a process that can separate the suspended particulate matter from the soluble and fluid components by the pressure forcing water or any kind of carrier fluid through a porous membrane. Having specific ratings of the pore sizes, membrane filters can keep the particles that are bigger than the size of the pores through the process of surface capture, as well as the particles which are smaller than the pore size of the membrane filter, can be kept by other types of mechanisms.

Membrane filters are useful tools for different purposes, so before you select the membrane filter for the applications, it’s important to know the types of procedures you are going to have, such as cross-flow filtration, ultrafiltration, microfiltration, nanofiltration, and reverse osmosis.

The procedure of cross-flow filtration is widely used for murky liquids such as wine, juice, in the food industry. It can be used in dialysis too. With the filter surface’s material of stainless steel, textile fabric, or plastic, The microfiltration is used in biotechnology applications, such as separating water-oil emulsions and separating colloidal hydroxides.

By using low pressures and membrane filters with bigger-sized pores, nanofiltration a be used in treatments performed for drinking water such as eliminating heavy metals and softening water. And the procedure of ultrafiltration is widely used only for protein separation and the cold sterilization in the pharmaceutical industry, but also for wastewater cleaning and metal recovering in the field of metallurgy.

Being the pressure-driven process, reverse osmosis is used to treat process, drinking, and aquarium water. We can also find them in where producing juice concentrates and treating wastewater.

https://www.hawachmembrane.com/membrane-material-and-performance-characteristics-of-filter-membrane/

Similarity And Difference Of Qualitative And Quantitative Filter Paper

 Hawach is a professional lab science company. Its service industry covers many fields such as life science basic research, clinical disease diagnosis and control, development and application of biological products, pharmaceuticals, commodity inspection and quarantine, population and health, food safety, agriculture, forestry, animal husbandry, and fishery and so on.

Its main products range from the filter cartridge, bottle-top dispenser, filter paper, pipette, to flash column, HPLC column and stainless steel molecular distillation, and so on.

Qualitative analysis filter paper generally has more residual ash, which is only used for general qualitative analysis and for filtering sediment or suspended matter in solution and cannot be used for quality analysis. When filtering the sediment, we should pay attention to:

1. Natural filtration is generally used, and the filter paper body and the ability to trap solid particles are used to separate liquids and solids;
2. Due to the ordinary mechanical strength and toughness of the filter paper, it is suitable to use less suction to filter. If it is necessary to speed up the filtration speed, stack 2 ~ 3 layers of filter paper in the funnel according to the suction force when filtering by the air pump. When using vacuum suction filtration, first put a layer of dense filter cloth on the funnel, and then put filter paper on it to filter;
3. Filter paper should not filter hot concentrated sulfuric acid or nitric acid solution.

The similarity between Qualitative and Quantitative Filter Paper
The type and specification of qualitative filter paper are basically the same as that of quantitative filter paper, which provides fast, medium speed and slow speed.

In the production process of filter paper, the raw materials are treated with various acids such as hydrochloric acid, and the impurities in the paper fiber were removed by distilled water so that the residual ash after burning remains little, which has little effect on the analysis results and brings beneficial for precise quantitative analysis.

Difference between Qualitative and Quantitative Filter Paper
The difference between quantitative filter paper and qualitative filter paper is in the ash amount produced after ashing. The qualitative filter paper may not exceed 0.13%, and the quantitative filter paper may not exceed 0.0009%. Ash free filter paper is a quantitative filter paper, which provides with ashless than 0.1 mg, this weight is negligible on the analytical balance. Note that both quantitative filter paper and qualitative filter paper are cellulose filter paper, which cannot be used to other types of filter paper such as glass microfiber filter paper.

HAWACH specially designs three kinds of filter papers with different flow rates to meet the needs of users with different uses: fast, medium speed, and slow speed. Different types of filter paper have different physical and chemical indexes. HAWACH quantitative filter paper has different sizes and specifications, taking into account the filtration speed and particle interception effect. It is used for particle collection in food analysis, soil analysis, and air pollution monitoring. It is also used for inorganic analysis in the construction industry, minerals, and steel industry.

https://www.hawachfilterpaper.com/similarity-and-difference-of-qualitative-and-quantitative-filter-paper/

The Interview Of QuEChERS Method Developer To Clear Your Doubts

 QuEChERS method is a rapid sample preparation technology for agricultural product testing for years and it’s Indispensable for many testers. HAWACH is dedicated to facilitating the experiment process by providing the extraction tube and purification tube. HAWACH has summarized the interview of the QuEChERS method developer for us to know it better and learn from it.

Three biggest improvements
Q1: QuEChERS was first introduced in 2003. Until now, what do you think are the three biggest improvements in this method?

A: In the design stage of QuEChERS, we conducted many experiments on a wide range of representative pesticides and samples to evaluate each extraction and purification step.

The original 2003 version of QuEChERS was good for the analyte and its matrix, even better than the current version. When we validated the method for hundreds of pesticides in different samples, we found that about 10 pesticides were easily affected by PH, and the use of PH 5 buffer was a good solution in the process. In the following method, we also pay attention to the use of a buffer. This is the first improvement of the method (the shortcoming is that the use of buffer will also lead to an increase in some impurities, so we would rather call this to adjust the method).

Secondly, the addition of C18 filler and PSA can significantly improve the purification effect of some samples, especially those rich in oil, such as olive oil, which will not cause the loss of the test substance. Lehotay regrets the failure to unify the use of C18 in AOAC2007.01 and EN 15662: AOAC official method 2007.01 does not mention that C18 can be added, but the EU standard method EN 15662 does. Some chemists have taken the method of freezing to reduce the interference of lipids, which can also remove some impurities introduced in the previous extraction. The freezing method is equivalent.

Finally, for the removal of impurities such as chlorophyll and carotenoids, a small amount of graphitized carbon black as described in CEN standard method 156627 or ChloroFiltr adsorbent can be added, which will cause about 25% of certain planar structure pesticide loss. Another thing that needs to be added is that when you encounter cereals that contain more fat, you can increase the amount of PSA.

Expanded scope of application
Q2: Although QuEChERS was originally a method for extracting multiple pesticide residues in fruits and vegetables, it has been used in more and more fields (such as vet drugs, PAHs, and antibiotics) and tests more different samples (such as plasma, meat, soil). These methods may not have been tested in the room as carefully as you did before. Do you think this is overdone?

A: We are very happy that QuEChERS can be expanded and used in different fields. According to the use effect of the method in the work, it is a case-by-case basis. In all newly developed methods, everyone must pay attention to assess their effectiveness.

From the beginning, we did not patent the QuEChERS, first because we felt that chemical methods or matrix extraction could not be patented (after all, Tswett had used sorbent for chromatographic separation before using capillaries).

Second, we all think that if you don’t intervene in this, the QuEChERS method will be used in more fields. Neither we nor our team has benefited from the commercialization of QuEChERS.

Both the AOAC method 2007.01 and the CEN standard method EN15622 are validated methods. The adjusted version is acceptable as long as it is fully validated and suitable for use. However, we have noticed that in the development of certain methods and the limited number of verification tests, although the spiked samples can obtain good and stable recovery rates, for real samples with strong interactions between certain matrices and analytes or instrument maintenance problems in the routine analysis may lead to exceptions.

For example, the first thing we should doubt is the application of QuEChERS in soil analysis, because a stronger extraction environment is needed at this time-pressurized extraction (PLE) or Soxhlet extraction instead of manual extraction, to overcome strong adsorption of soil-sediment. Many foods do not have such a strong force, so hand extraction has a satisfactory recovery rate.

Other uses
Q3: QuEChERS was originally designed for trace pesticide residue analysis. The laboratories using this technology are mainly pesticide laboratories, who are very familiar with the collection of representative samples and data statistics. But now QuEChERS has been used by many non-pesticide laboratories for a variety of samples for trace analysis. Such laboratories often lack experienced professionals like previous pesticide analysts, so do you think the QuEChERS method will have a negative rap because the sample collection in the process is not representative?

A: Yes, not just QuEChERS. In fact, we must consider the sample requirements when using all detection methods. Whether it is in our earliest paper, or in future papers and reports, we have repeatedly emphasized that sample collection and homogenization are inseparable steps in the QuEChERS step, because it also helps to obtain smaller sample particle sizes and subsequent shaking extraction.

For pesticides
Q4: I have heard that there are more than 400 pesticides that can apply QuEChERS in different matrix analysis so far. In addition to the planar ring-shaped pesticides that can be strongly adsorbed by the graphitized carbon black in the dispersion matrix extraction, are there other types of pesticides that may not (perhaps the recovery rate will be very low) adopt the official QuEChERS method? If so, do we have any solutions?

A: Anastassiades and his colleagues have developed a database that allows the systematic collection and online retrieval of the recovery data generated in the framework of cooperative or stand-alone verification experiments. This database currently stores more than 150,000 data on the recovery of more than 650 pesticides and their metabolites in 115 different foods, which also includes other common multi-pesticide methods. Recycling data is indeed a good source of information for inspectors who need to know in a timely manner whether the recycling of methods in different pesticide-food combinations is normal.

Of course, there are still many pesticides that cannot be extracted by the QuEChERS method. Traditionally, these pesticides usually need to be analyzed by a separate detection method. Anastassiades is working hard to find suitable testing conditions for this type of pesticide.

Special problems that occur in the QuEChERS application
Q5: In the initial acetonitrile extraction, a certain amount of heat will be generated when adding anhydrous magnesium sulfate. In a sense, these heats can increase the extraction speed or extraction efficiency, but on the other hand, too much heat will cause some thermal instability or loss of volatile pesticide residues. In practice, how do you coordinate this contradiction? Perhaps, this is not worth mentioning at all?

A: We have proved that the method has a good recovery of hundreds of pesticides and different test substances. Heat may cause potential degradation of the few previously mentioned pesticides, but the acidic environment helps keep these pesticides stable. When using frozen samples, the temperature after extraction can be very moderate.
Any more questions, please contact HAWACH.
(The end)

https://www.hawach.com/the-interview-of-quechers-method-developer-to-clear-your-doubts/

Sterilization And Non-sterilization Of Syringe Filter

 Here is the basic method of using a syringe filter that you should know before you use it. First, you need to load the sample into the syringe. You can attach the filter by twisting it carefully. If you can find a Luer lock on the syringe, fix it firmly but not over-tighten.

The next step is to hold the syringe and the syringe filter vertically and make the membrane wet evenly, preventing air blocks and promotes high flow rates. Then you can press the syringe plunger very slowly and push the sample through the filter.

You’d better discard the first 0.25-0.5ml of the sample as it might be higher contamination in the first few drops of the sample. If you feel the back pressure ever increasing heavily, it’s time to change another syringe filter because the filter might have plugged. The filter housing will burst if you try to keep pressing it.

With syringe filters, particles which you don't need, and cause contamination and clogging of sensitive instrumentation, will be easily removed. By using the syringe filters. you will find more consistent and reliable results and less downtime of your equipment.

Due to too many options available and the many sample/analytical parameters that need to be considered, it is a big challenge to find the appropriate syringe filter with high quality. If you use the wrong filter, you might get the unexpected wrong results, find the premature column blocking, or drive the instrument out of work sometimes.

Appearance Attraction of Syringe Filter

Hawach syringe filter is beautiful, light, and clean, it is the first choice for filtering HPLC、GC small sample. And it is composed of fixtures and membranes, which can be reused by replacing microporous membranes and cleaning and sterilizing the fixture.

Sterilization and Non-sterilization Features of Syringe Filter

According to sterilization methods, Hawach syringe filter can be divided into sterilization and non-sterilization. Sterilizing syringe filter is a fast, convenient, and reliable filter processing device for small volume samples commonly used in the laboratory. It is mainly used for sterilizing and filtering of laboratory biological fluid, medium, and media additives.

Sterilized syringe filter has nine membrane types: MCE、PVDF、PES 、PTFE、PP、Nylon、CA、Glass Fiber and Hydrophobic PTFE. Sterilized syringe filter provides with 5 diameter specifications optional: 4 mm, 13mm、 25mm、33mm and 50 mm.

And sterilized syringe filter also provides with gamma-ray disinfection and sterilization, and causes no heat source. What’s more, it is easy to tear open type sticker single independent packaging; it has unique and easy to open outer box design, and it is not easy to pollute with easy-tracking procedures.