Description Of Chromatographic Column Installation Of Color Harmonic Column

Flush the pumps and piping of the chromatograph thoroughly with the filtered and degassed mobile phase (without buffer salts) so that the system is free of bubbles. According to the flow direction of the mobile phase marked on the chromatographic column, connect the inlet of the chromatographic column with the pipe at the pump end and the outlet of the column is not connected.

Set the flow rate of the pump to 0.1mL/min or lower, and the flow rate slowly rises to the normal flow rate (t > 5min). When the solvent flows freely from the exit of the column, set the flow rate as 0, and connect the column exit with the pipeline at the detector end.

The chromatographic column was balanced with the mobile phase and normal flow rate of 10-30 times column volume. Amino column, cyano column can be used in the positive phase environment, but also in the inverse phase environment. When it is necessary to change from the reverse phase into the positive phase or the positive phase into the reverse phase, it is necessary to use 20-30 times the column volume of THF as the transition solvent to flush the system, otherwise, it is easy to make the one-way valve of the pump blocked, abnormal pressure phenomenon.

Notes for chromatographic column use
Mobile phase: the solvent must be HPLC grade and the reagent should be as pure as possible. There is no chemical reaction with the fixed phase, the viscosity is small, and the sample has an appropriate solubility, k is required in the range of 1 ~ 10 (available range) or 2 ~ 5(the best range), k value is too small, is not conducive to the separation of k value. Too large and may precipitate the sample in the mobile phase. The mobile phase must be filtered and degassing d before use to ensure that the solvents are miscible with each other. The mobile phase must match the detector. For example, when the UV detector is used, the solvent whose cut-off wavelength is greater than the detection wavelength cannot be used.

Trace impurities can greatly degrade the performance of the column, ensuring that solvents (buffers) are miscible with each other when the mobile phase needs to be replaced. If the solvent used and the column of the solvent is not miscible, the use of transition solvent, otherwise the column will produce permanent damage. The separation of salt or buffer from the mobile phase can also permanently damage the column. The solubility of the sample in the mobile phase should be checked before each sample injection, and the sample should be dissolved in the mobile phase whenever possible.

Fixed phase: the pH value of the mobile phase should be kept between 2.0 and 8.0 (unless otherwise specified); Use pre-saturated column and guard column if necessary; When using an amino column, avoid aldehydes and ketones in mobile phase and sample.

Column packing can be divided into the following three: high pH (>8.0), silica gel dissolution. If the pH of the mobile phase is close to 2.0 or 8.0, a saturated column is required. Silica gel column: high column efficiency, high mechanical strength, but sensitive to pH, low pH (<2.0) will cause the bonding phase to hydrolyze (bond removal of functional groups).

Organic polymer packing: in the wide range of stable residual silica hydroxyl effect is small, but its column efficiency is low. Mechanical strength is not high and may shrink or swell in different solvents. In the application process, the pressure must not exceed its maximum bearing range. And mobile phase loyalty, organic solvents such as methanol. The content of isopropanol ethanol should not exceed 10%.

A new type of organic-inorganic hybrid filler with two high – purity monomers. Synthetic high purity filler which combines the advantages of silica gel and an organic polymer. High efficiency, high mechanical strength, good stability, wide ph range.  The silicon hydroxyl group can be effectively shielded for the most part. So that it has better retention of alkaline substances.

Back pressure and flow rate
Keep the back down to 3,500 psi. Avoid any sudden changes in stress. If the back pressure is high, the column can recoil, but the flow rate should be 1/5 to 1/2 of the normal flow rate. If the test pool needs to be degassed, use the back pressure governor. In order to extend the service life of the chromatographic column to the greatest extent, the velocity of flow can be adjusted according to the particle size of packing and the inner diameter of the chromatographic column. So that the back pressure does not exceed the limit.

Column temperature
Most of the separation is done at room temperature, and if the temperature in the lab stays the same, there will be no problems. But most work environments have temperature fluctuations. The retention time of temperature equivalence separation has an effect. Even under the condition of the constant temperature of day and night, the room temperature will change greatly due to the difference in temperature between day and night. Especially when large quantities of samples are analyzed, there will be large differences. The separation of compounds is achieved by controlling the temperature. The retention time and selectivity of the column change with the change of temperature, and the peak width also change.

Preservation of chromatographic column
The preservation condition of the column will affect the life of the column. The storage solution should contain at least 20% organic solvent to prevent the growth of microorganisms. Never use buffer to store chromatographic column, wash chromatographic column with 5 times column volume of mobile phase without a buffer to remove buffer and salt.

Description Of Chromatographic Column Installation Of Color Harmonic Column

Theory, Evolution, And Methods Of Extraction Thimble

Theory
The transfer of a substance from one solvent to another by taking advantage of the difference in the solubility or the distribution coefficient of a substance in two insoluble (or slightly soluble) solvents. After repeated extraction, most of the compounds were extracted.

The solvent extraction process generally consists of extraction, washing, and reverse extraction. Generally, the process of extracting the solute from the organic phase is called extraction, the process of removing other solutes or contents from the loaded organic phase is called scrubbing, and the process of water phase parsing the solute from the organic phase is called stripping.

The distribution law is the main basis of the extraction method theory. At the same time, when a certain soluble substance is added to two kinds of insoluble solvents, it can be dissolved in two kinds of solvents respectively. The experiment proves that, at a certain temperature, when the compound and the two kinds of solvents do not have decomposition, electrolysis, association, and solvation, the ratio of the compound in the two liquid layers is a constant value. This is true regardless of the amount of material added.

Organic compounds are generally more soluble in organic solvents than in water. Extracting compounds dissolved in water with organic solvents is a typical example of extraction. During extraction, if a certain amount of electrolyte (such as sodium chloride) is added into the aqueous solution, the extraction effect can be improved by using the “salting-out effect” to reduce the solubility of organic matter and extraction solvent in the aqueous solution.

To extract the required solute completely from the solution, one extraction is usually not enough and must be repeated several times. The residual amount of the compound after extraction can be calculated by using the relation of the distribution law.

When you use a certain amount of solvent, you want to have as little left in the water as possible. In other words, it is better to divide the solvent several times and do multiple extractions than to do one extraction with the whole amount of solvent. But it should be noted that the above formula applies to solvents that are almost insoluble with water, such as benzene, carbon tetrachloride, etc. And water with a small amount of mutual solvent ether, the above formula is only approximate. But you can still qualitatively point to the expected outcome.

Instrument: dispensing funnel
Common extractants: toluene, dichloromethane, trichloromethane, gasoline, ether, straight-run gasoline, n-butanol, carbon tetrachloride.
Requirements: the extraction agent and the original solvent are immiscible.
The extractant and the solute do not react with each other.

The solubility of the solute in the extractant is much higher than that in the original solvent.
Correlation law: organic solvent is soluble in the organic solvent, the polar solvent is soluble in the polar solvent, and vice versa.

Evolution
In 1842 e. – m. Perillo studied the extraction of uranyl nitrate from nitric acid solution by ethyl ether. In 1903 l. edilanu used liquid sulfur dioxide to extract aromatic hydrocarbons from kerosene, the first industrial use of extraction.
In the late 1940s, the need to produce nuclear fuel spurred extraction research and development.

Today extraction is used in the petroleum refining industry and is widely used in the chemical, metallurgical, food, and atomic industries. For example, extraction has been used in the separation and refining of petroleum fractions, the extraction and purification of uranium, thorium, plutonium, the extraction and separation of non-ferrous metals, rare metals, precious metals, antibiotics, organic acids, alkaloids, and wastewater treatment.

Methods
Two co-existing liquid phases are formed by adding an extractant that is insoluble (at most partially soluble) with the solution to be separated. The dissolubility of each component (including the dissolution after chemical reaction) of the original solvent and the extractant is used to make them not equally distributed in the two liquid phases. For example, an aqueous solution of iodine is extracted with carbon tetrachloride. Almost all iodine is moved into carbon tetrachloride, and iodine is separated from a large amount of water.

The most basic operation is single-stage extraction. It is to make the material liquid and extraction agent contact closely in the mixing process, so that the extracted components through the interphase interface into the extraction agent, until the components in the two-phase distribution is basically balanced. After that, the liquid was separated into two layers, that is, the extraction liquid changed from the extraction agent and the raffinate changed from the material liquid. When the single-stage extraction reaches the phase equilibrium, the phase equilibrium ratio of the extracted component B is called the distribution coefficient K.

The extraction rate (the ratio between the amount of extracted components in the extraction solution and the initial amount in the raw material solution) that can be achieved by single-stage extraction for a given component is relatively low, which often fails to meet the technical requirements.

In order to improve the extraction rate, a variety of methods can be adopted:
(1) multi-stage cross-flow extraction.
(2) multistage countercurrent extraction. Continuous countercurrent extraction. In the differential contact extraction tower (see extraction equipment), the material liquid and extraction agent contact mass transfer in the process of reverse flow, is also a common industrial extraction method.

The material liquid and extraction agent, the density is called a heavy phase, the density is called the light phase. The light phase enters from the bottom of the tower and overflows from the top. The heavy phase is added from the top of the tower and exported from the bottom of the tower. When the extraction column is operated, a liquid phase filled with the whole column is called the continuous phase. The other liquid phase is usually dispersed in the form of droplets and is called the dispersed phase. The dispersed phase liquid disperses when it enters the tower, and then condenses and stratifies before leaving the tower.

Theory, Evolution, And Methods Of Extraction Thimble

The Product Features Of Bottle-Top Dispenser

Continuous pipetting can be completed quickly and easily. Connected to the PD-tip, the Hawachadjustable dosing device (continuous pipetting) is effective and durable, allowing you to perform as many as 49 repeated injections in one aspirate. PD-tips are available in 8 sizes, with a volume from 0.1 ml to 50 ml, allowing you to easily remove reagents from 2 microliters to 5 ml. Its accuracy and durability are just as good as your Expected as high.

Main features of bottle-top dispenser:
★ The liquid dispenser can be sterilized at high temperature and high pressure.
★ The silicone tube of the liquid filler is made of special materials, durable, and not easy to break.
★ Easy to use, reliable, high efficiency, small repeat error, can save the time and cost of research and experiment.
★ The material parts of the liquid contacting parts of the liquid filler are glass and polypropylene, which do not react with common chemical reagents.
★ The upper and lower one-way piston and glass plunger of the liquid filler is precision ground, and the sealing is good, which ensures the accuracy of the liquid volume.
★ Volume selection button-five gears for an easy selection to control pipetting volume.
★ Pipetting control keys-even the smallest amount of pipetting can be easily controlled.
★ Multi-function tip lock/suction key-integrated design avoids the accident of lock damage that may occur in the separate design.

The Hawach adjustable dosing device (continuous pipetting) is suitable for Hawach tips, as well as other piston tips.
-Easy to operate.
-It has been calibrated before leaving the factory.
-No maintenance.

Main features of the automatically adjustable quantitative dosing device
1. The use of micro-processing technology makes the operation tend to be humanized.
2. A variety of control methods, which can be controlled individually and centrally.
3. Manual control, automatic control, and external trigger control can be used to meet the needs of different occasions.
4. Using color LCD and touch screen technology, the operation interface is simple, intuitive, and clear.
5. The multi-channel driver is selected, which is suitable for the needs of different irrigation volumes and different accuracy.
6. The stepping motor drives the pump head, which is easy to control the start and stop, so it has high precision and is very suitable for quantitative filling. The straight brush motor drives the pump head, which has large output torque and is maintenance-free.

working principle of bottle-top dispenser:

Use the rotating wheel to roll the flexible hose. The fluid in the hose moves with the rotation of the wheel. Just like squeezing a hose filled with fluid with your finger, the fluid slides forward along your finger. The pump uses a rotating roller to squeeze the hose to complete the fluid delivery.

product advantages of bottle-top dispenser:

1. No pollution: the fluid only touches the pump tube, not the pump body;
2. High accuracy: high repeat accuracy and high stability accuracy;
3. Good sealing: it has the good self-priming ability, can be idling, and can prevent backflow;
4. The maintenance of the hose pump is simple: there are no valves and seals, and the hose is the most vulnerable part;
5. Can pump liquid, gas, solid or multi-phase mixture;

Hawach can provide different types of bottle-top dispensers for your choice. If you have any problem with that. Don’t hesitate to contact us.

The Product Features Of Bottle-Top Dispenser

Steps To Use Pipette Correctly

The pipette, also known as pipet, pipettor, or chemical dropper, is some kind of instrument in the laboratory. The pipette is especially for measuring the liquid volume and absorb the liquid to move it to other containers. In general, the pipette is mostly used in the biological experiment or chemical experiments.

Through a large number of designs, different degrees of accuracy and precision are achieved. Currently, the applied types range from the single-channel pipette to the complicated electronic control digital pipette. Moreover, a lot of pipettes can form partial vacuum above the liquid level within the container, and absorb or discharge the liquid by optionally adjusting the vacuum volume. However, the degrees of accuracy of measuring have significant differences according to different types of pipettes.

The world’s first micropipette was invented by the German Dr. Hans Schmitz in 1960. Afterward, Heinrich Netheler, the founder of Eppendorf company, inherited the patent right and started the commercial production of micropipette in the 1960s. In terms of the adjustable pipette, it was invented by a group of people who come from Wisconsin, the US. Among them, the main inventors include Warren Gilson, and Henry Lardy, professor of biology and chemistry at the University of Wisconsin–Madison.

Steps to use pipette correctly
The step of pre-wetting suction liquid is beneficial for viscous liquid to achieve a good effect, the operation mechanism is as follows: firstly, the pipette should inhale the sample liquid, then discharge, suction headwall will adsorb a layer of liquid, so that the surface adsorption can become saturation quickly, and then inhale the sample liquid, finally discharge the volume of the liquid.

1. Pre-use check: check the pipette mark, accuracy level, scale mark position, etc.
2. Suction: pinch the upper end of the pipette with the right thumb and middle finger, insert the lower mouth of the pipette into the solution to be absorbed, generally 10-20mm. Use the ear-ball to absorb the solution to the tube.
3. Adjust the liquid level: lift the pipette upward to leave the liquid level, the end of the pipette still resting on the inner wall of the container. The pipe body remains upright, then a sightly relaxed finger so that the solution can flow out of the tube from the lower mouth slowly, until the bottom of the meniscus of the solution and the line tangent, then immediately press the tube mouth. Remove the tip of the droplet against the wall, then move the pipette and insert it into the receiver.
4. Release solution: make the pipette upright, the lower end of the pipe should be close to the wall of the receiver bottle. Slightly loosen finger, let the solution flow slowly along with the wall o bottle, after all the solution flows, please wait for 15s to take out the pipette, in order to make the part of the solution attached to the pipe wall to flow out. If the pipette is not marked “blow”, no needs to blow out the solution remaining in the end o the pipette tip, as the pipette calibration volume does not include this part of the residual solution.

Steps To Use Pipette Correctly

How Flash Column Works

Flash refers to the saturated water and saturated water under the pressure of the container when the saturated water at high pressure enters the container at low pressure. In the process of chemical production, the flash tower can realize the rough gas-liquid separation of materials, and the flash tower can be roughly separated before entering the atmospheric furnace, so as to reduce the load of the atmospheric furnace.

When water is heated at atmospheric pressure, 100℃ is the maximum temperature allowed for liquid water at that pressure. Reheating does not raise the temperature of the water but converts it into steam. The heat absorbed by water in the process of heating to the boiling point is called sensible heat, or sensible heat of saturated water. The heat required to convert saturated water into steam at the same atmospheric pressure is called latent heat.

However, if the water is heated under a certain pressure, the boiling point of the water will be higher than 100℃, so more sensible heat is required. The higher the pressure, the higher the boiling point of water, and the higher the heat content. When the pressure drops, some sensible heat is released, and this excess heat is absorbed in the form of latent heat, causing part of the water to “flash” into steam.

In fact, in the distillation calculation of the tower, each theoretical plate is required to perform such a flash calculation, but the general name is the “equilibrium stage” calculation, which is more rigorous in theory, and the content of the calculation is exactly the same. Each strict or “flash” calculation or “equilibrium stage” calculation must satisfy the following three major equilibria: mass equilibrium, energy equilibrium, and phase equilibrium. Thus, a standard “flash” calculation module can handle changes in pressure (rise or fall) as well as the exchange of heat and work.

The exchange of internal and external work and heat exchange are mainly reflected in the energy balance, while the mass balance and phase balance mainly determine the vaporization fraction and the composition of the vapor and liquid phases. In addition, the “flash” calculation has a very important and difficult task, which is to judge whether the state you specify is in the vapor and liquid phases, or just the vapor phase or liquid phase only. In addition, the calculation of liquid-liquid equilibrium generally requires the “flash” calculation, of course, some software is taken out alone, because the calculation is more difficult.

Operating principle
Flash column is when the saturated water at high pressure enters the container at low pressure and becomes saturated water vapor and saturated water under the pressure of the container due to the sudden decrease of the pressure. By taking advantage of the differences in the volatilization of the components in a liquid mixture, the method of partially vaporizing the components in the vapor phase with the medium of heat energy to enrich the light components in the liquid phase and separate them by combining the components.

Causes of flash:
When water is heated at atmospheric pressure, 100℃ is the maximum temperature allowed for liquid water at that pressure. Reheating does not raise the temperature of the water but converts it into steam. The heat absorbed by water in the process of heating to the boiling point is called sensible heat, or sensible heat of saturated water. The heat required to convert saturated water into steam at the same atmospheric pressure is called latent heat.

However, if the water is heated under a certain pressure, the boiling point of the water will be higher than 100℃, so more sensible heat is required. The higher the pressure, the higher the boiling point of water, and the higher the heat content. When the pressure drops, some sensible heat is released, and this excess heat is absorbed in the form of latent heat, causing part of the water to “flash” into steam.

The actual situation
Flash column appears in the pipeline system, easy to cause cavitation damage to the valve, you can choose anti-cavitation high-pressure valve, its characteristics are multiple throttle allocation of pressure difference, also can choose cavitation erosion material. Flash can also be used as energy for recovery of boiler drainage and geothermal power generation in thermal power plants.

How Flash Column Works

Application Of QuEChERS Method In The Detection Of Drug Residues In Foods Of Animal Origin

Who is HAWACH?
Over the years, with the consistently high-quality, professional-level technical services and excellent reputation of the products, HAWACH has won the praise of domestic and foreign customers, its products ranging from SPE/FLASH/ HPLC column, vacuum filtration, membrane filter, bottle-top dispenser, syringe filter, extraction thimble, sample vial, filter paper and etc. Also, HAWACH provides flexible QuEChERS kits, including centrifuge tubes, extraction tubes, purification tubes, and reagent bags of different specifications, to help you quickly establish standard-compliant detection methods.

QuEChERS highlights
Compared with traditional solid phase extraction and other methods, the QuEChERS method is fast, efficient, environmentally friendly, stable and durable, and has been used in animal-derived foods including antibiotics, pesticides, and illegal drugs. With the further development and improvement of the QuEChERS method, it will become the most convenient and commonly used method in the field of drug residue analysis in the future.

Detection of drug residues in foods of animal origin
At present, there are hundreds of drugs that may have residual risks in the livestock and poultry and aquaculture processes, so there is an urgent need to establish an efficient, simple, stable, and reliable detection method. The QuEChERS method is a promising choice for solving this problem.
Veterinary medicine can prevent and treat animal diseases and is widely used in livestock and poultry farming. Its residue in animal food will bring greater risks to food safety. The public report on the detection of veterinary drug residues in animal tissues using the QuEChERS method was first seen in 2005. Fagerquist et al. used the QuEChERS method to detect β-lactam antibiotic residues in cattle kidneys. Water and acetonitrile were used as extraction reagents, and C18 was used as an adsorbent for fast removal and then analyzed by liquid chromatography-tandem triple quadrupole mass spectrometry (LC-MS / MS).

Pérez-Burgos et al. found that beef samples were extracted by the QuEChERS method, and then added C18, PSA, and MgSO4 for d-SPE adsorption purification. Finally, the LC-MS / MS was used to analyze and detect cephalosporin antibiotics. The results show that, compared with the traditional SPE method, the new method has higher sensitivity and can meet the requirements of relevant EU regulations.

Antiparasitic drugs
Antiparasitic drugs are also commonly used in livestock and poultry farming, and their residual animal-derived foods will also cause great harm to human health, so they need to be included in the scope of supervision and testing. Kinsella et al. used a modified QuEChERS method to detect the insect repellent monetil and its sulfone derivatives in lamb and goat milk. A one-step enrichment process was added to the method to improve sensitivity. Graded mass spectrometry (UPLC-MS / MS) analysis showed that the recovery rates of the two targets were 108% -109%, and good chromatographic separation results were obtained within 13 minutes.

Application Of QuEChERS Method In The Detection Of Drug Residues In Foods Of Animal Origin

310rpm Water Bath, LCD Display Horizontal Condenser Rotary Evaporator

RE1-W-L series-horizontal condenser is a water bath type rotary vacuum distiller with the effective horizontal condenser. Since the vacuum suction head is horizontally located, the vacuum pump can be conveniently connected to the suction head. This design facilitates the evaporating gas to directly enter the condensing tube quickly, thus improving the working efficiency of rotary vacuum distiller.

This series 

rotovap price is very favorable compared with other water bath rotary evaporators. Because the horizontal condenser design requires a bigger space, big size like 5-liter rotovap, 10L rotovap, 20-liter rotovap, and 50L rotovap do not adopt this design.

Features of RE1-W-L series-horizontal condenser rotary vacuum distiller

1. Water bath horizontal condenser rotary vacuum distiller has a temperature range of RT-99°C. With automatic overheat protection function to prevent the material from changing due to excessive temperature.
2. Rotovap price for RE1-W-L series-horizontal condenser is very cost-effective.
3. Unlike the big size 

20L rotovap and 50-liter rotovap, a horizontal condenser rotary vacuum distiller has the fastest rotating speed of 310rmp/min, which can be used for most crystalization experiment.

4. Backflow prevents the design of a rotary vacuum distiller makes experiment more efficient and prevents sample liquid from coming into the pump to break.
5. With vacuum gauge, effectively prevent the vacuum pump liquid into rotary vacuum distiller.
6. Sealing parts: choose the latest fluorine rubber and PTFE composite material imported, through special processing, enhance the sealing, anti-corrosion and wear resistance.
7. Efficient horizontal condenser tube, with double reflux condenser of large condensation area, which improves the distillation efficiency.

310rpm Water Bath, LCD Display Horizontal Condenser Rotary Evaporator