Learn The Nature Of The Sample, Choose The Right HPLC Column

Widely used in pharmaceuticals, High-performance liquid chromatography (HPLC) is found a very effective way to determine the assay and related substances in drug substances. The scientists use them for the components’ separation of the mixed drug substance.

HPLC column is always playing an important role when you separate different compounds because of the stationary phase in its column. The sample will pass through the column with the mobile phase, and its components will be separated when coming out from the other end of the column.

Acting as a carrier in the separating process, the mobile phase will be pumped into the system by the mechanical pumps. After that, the sample will be led into the mobile phase in the column at a fixed flow speed.

When you put a mixture of the compound into the column, the compounds will be separated upon its basis of polarity. If the stationary phase is non-polar, a polar compound will be eluted first, as the non-polar compounds are attracted by the mobile phase.

According to the different column types, the stationary phase can be polar or non-polar particles. We can figure out which one is the right choice after we learn the nature of the sample we are going to analyze.

Hawach HPLC Autosampler Vials, Always Protect Against Your Sample Loss‎

For the scientists who use the chromatography vials in the lab, the vial might be just is a temporary little container that can hold a sample for a while, and then the sample can be analyzed by chromatography process safely. Yes, it is totally true, but if you choose the right vial and use it properly, you can find it can be a big help for you to get the results from your application as accurately as possible.

You can find Hawach vials for HPLC in the group of different diameter and height of the vial. The factors of both clear glass and amber glass are highly inert, but Amber glass can avoid exposure to UV light, and protect the samples which have sensitive nature. The vials are primarily used to inject samples from an autosampler, so the 2 mL vials are used more generally. During the injection process, the autosampler needle can pierce through the cap of the vials and withdraws the sample in the required amount from the vials.

From the material in the caps to the high-quality USP1 and Borosilicate glass for the vial, HAWACH continuously addresses every detail that can deliver gains for you. You can find a big range of HPLC autosampler vials and the accessories just the right solution to store and protect your samples.

Learn The Nature Of The Sample, Choose The Right HPLC Column

Retention Mechanism Of SPE Cartridge

The retention mechanism of solid-phase extraction can be divided into two categories. Most compounds apply this mechanism that fillers retain target compounds, filler retains its target component and a small amount of impurity, a small amount of impurity adsorbed on the column is removed by elution step, and finally, a suitable solvent is selected to elute the target component. According to the retention mechanism of adsorbent, it can be further divided into:

(1) Inverse phase: it comprises C18, C8, CN, Phenyl, C4, and C1. Analytics is from non-polar to moderate polarity. Matrix is water solubility. Methods are as followed: a. activation: usually activated with water-soluble organic solvents such as methanol, followed by water balance; b. elution: elution of impurities by buffer solution containing 0-50% polar solvents; c. elution: polar or nonpolar solvent elution of target.

(2) Positive phase: it comprises Silica, Florisil, Diol, and NH2. The analyte is from moderate to strong polarity. The matrix is from nonpolar to medium polarity. The specific methods are as followed: a. activate nonpolar organic solvent; b. elute nonpolar organic solvent.

(3) Cation exchange: the specific methods include activation, sample loading, and elution. Firstly, activation: when used in a sample in a nonpolar organic solvent, the sample solvent may be used to activate; when used in a sample in a polar solvent, the water-soluble organic solvent may be used after the column, then balanced with water, and finally with a buffer solution of appropriate pH value. Secondly, sample loading: the pH value of the sample solution is less than its pKa two units to ensure its charge.

(4) Anion exchange: the methods are as followed: firstly, activation: sample solvents are available for use in samples in nonpolar organic solvents; water-soluble organic solvents are available for use in samples in polar solvents, then balanced with water and, finally, with buffer solutions of appropriate pH values. Secondly, sample loading: the value pH the sample solution is greater than its pKa two units to ensure that it is charged. Third, elution: the value pH the elution solution should be less than its two units pKa.

This mechanism is used to remove impurities such as pigments in food. Fillers retain impurities without or only a very small number of target components, so after the sample began to collect the target components, then the target in the solvent is further elution, and finally combined upper sample and eluent effluents.

Retention Mechanism Of SPE Cartridge

Hawach To Talk About The Applications And Differences Filter Membrane

1. Nylon membrane
Nylon membrane is a synthetic long-chain polyamide membrane, which has a strong binding ability to nucleic acid and protein and can replace nitrocellulose membrane for molecular imprinting and hybridization experiments.

Nylon membrane features good temperature resistance, which can withstand 121℃ saturated steam hot-press sterilization for 30min, maximum working temperature is 60℃; also, it has good chemical stability, which can withstand dilute acid, dilute alkali, various organic and inorganic compounds such as alcohols, esters, oils, hydrocarbons, halogenated hydrocarbons, and organic oxides. It has the widest applications, such as aqueous solution and organic mobile phase filtration; filtration of beverage and chemical liquid; filtration of tissue culture medium, and so on.

2. PVDF-Polyvinylidene fluoride membrane
PVDF membrane, or polyvinylidene fluoride membrane, is a kind of solid-phase support commonly used in Western blotting. The PVDF membrane is hydrophobic, and the pore size of the membrane can be large or small. As the pore size of the membrane continues to decrease, the membrane is more firmly bound to low molecular weight proteins. For proteins larger than 20000, a 0.45um membrane is used, and for proteins smaller than 20000, a 0.2um membrane is used. The use of the PVDF membrane requires pretreatment. The purpose of methanol treatment is to activate the positively charged groups on the membrane, making it easier to bind to negatively charged proteins. With high mechanical strength, the PVDF membrane is an ideal solid support material in the imprinting method.

3. NC membrane
Nitrocellulose filter membrane (NC membrane for short) is used in Northern Blot, Southern Blot, and Western Blot. Hybridization techniques include solid-phase hybridization and liquid-phase hybridization. Solid-phase hybridization technology is currently more commonly used. First, the nucleic acid to be tested is bound to certain solid-phase support and then hybridized with the labeled probe in the liquid phase. Nitrocellulose membranes are commonly used for solid supports.

Comparison among the above three
Nylon membrane is an ideal nucleic acid solid support and there are many types; nitrocellulose membrane is currently the most widely used solid support with the cheapest price; the PVDF membrane is somewhere in between.

1. In terms of binding capacity: nylon membranes can bind DNA and RNA up to 480-600μg / cm2, and can bind nucleic acid fragments as short as 10bp; nitrocellulose membranes can bind DNA and RNA up to 80-100μg / cm2. The 200bp nucleic acid fragment has a weak binding ability; the PVDF membrane can bind DNA and RNA up to 125-300μg / cm2.

2. In terms of temperature adaptability: after the nylon membrane is baked or irradiated with ultraviolet rays, some of the pyrimidine bases in the nucleic acid can be combined with the positive charge on the membrane; the nitrocellulose membrane relies on hydrophobic interaction to bind DNA and the binding is not strong; The PVDF membrane is firmly bonded and resistant to high temperatures, and is particularly suitable for Western blotting.

3. In terms of toughness: the nylon membrane is stronger; the nitrocellulose membrane is more brittle and easily broken; the PVDF membrane is stronger.

4. In terms of repeatability:
(1)The nylon membrane can be used repeatedly for molecular hybridization. After hybridization, the probe molecules can be eluted by alkali denaturation; the nitrocellulose membrane cannot be reused; the PVDF membrane can be reused.

(2) The use of the NC membrane is also very simple. For example, no formaldehyde pretreatment is required, as long as it is infiltrated on the surface of non-ionized water to expel the air bubbles in the membrane, and then equilibrated in electrophoresis buffer for a few minutes; the NC membrane is easy to close, nor particularly strict cleaning conditions are required. The protein transferred to the NC membrane can be stored stably for a long time under appropriate conditions, but it should be noted that the pure nitrocellulose membrane is relatively brittle and easy to roll, and the operation should be careful during use.

Because it can’t stand many “tortures”. When choosing a nitrocellulose membrane, it is necessary to choose a suitable pore size. Generally, large molecular proteins above 20KD use a membrane with a pore size of 0.45um. If the membrane is less than 20KD, it is recommended to choose 0.2um. Also, note that the selection of pure NC membrane mixed with cellulose acetate (CM) -containing the NC membrane will reduce the binding force.

(3) Since the protein-bound on the NC membrane will be replaced by some detergents, use a milder Tween20 when blocking, and the concentration should not exceed 0.3%. Generally speaking, the purer the NC membrane, the higher its protein binding capacity, so it is a consideration to increase the sensitivity and resolution of WB and improve the purity of the membrane used. If the NC membrane is mixed with some cellulose acetate, which has been mentioned before, it will affect the protein binding

(4) Compared with nitrocellulose membranes, PVDF membranes have superior performance in protein retention, mechanical strength, and chemical compatibility. The typical binding capacity of commercially available nitrocellulose membrane is 80-100μg / cm2, while the binding capacity of the PVDF membrane is 100-200μg / cm2 (and the binding strength PVDF is 6 times stronger than nitrocellulose membrane!). But the biggest advantage of PVDF membranes is not only this: better mechanical strength and chemical resistance make PVDF membranes ideal for various staining applications and multiple immunoassays, and a single lane copy of the gel can be used for multiple purposes, in particular, it is necessary to do N-terminal protein sequencing.

Under fairly “severe” cleaning conditions, the PVDF membrane remains intact when the nylon or nitrocellulose membrane has been degraded, so PVDF is also the best choice for protein sequencing. But it is not suitable for fluorescence. Particular attention should be paid to PVDF membranes that require 100% methanol pretreatment (not more than 15 seconds) and then equilibrated with buffer before they can be used.

Hawach is specializing in providing different kinds of filter membranes to meet various lab requirements. Welcome to visit hawach.com for more details.

Hawach To Talk About The Applications And Differences Filter Membrane

The Difference Between Filter Paper And Chromatography

Filter paper in the chemical experiment is a relatively important supply, so, we want to be skilled in the use of filter paper, which is a necessary procedure in each of our chemical experiments. Filter paper most filter paper is made of cotton fiber, so we have to use different methods for different purposes. Moreover, because it is made of fiber, it has innumerable holes in its surface through which liquid particles can pass, whereas larger solid particles cannot.

This property permits the separation of mixed liquid and solid substances. What’s more, the filter paper is a kind of filter tool commonly used in chemical laboratories. It is usually round in shape and made of cotton fiber. In addition, paper chromatography is based on filter paper as an inert support. Filter paper fiber and water have a strong affinity, can absorb about 22% of the water, and 6~7% of the water in the form of hydrogen bond and cellulose hydroxyl, in general conditions more difficult to remove, and filter paper fiber and organic solvent affinity are very weak.

Because the cotton fiber in filter paper has a good affinity for water, it can absorb about 22 percent of water, of which 6 to 7 percent is bound to cellulose in the form of hydrogen bonds. In general, it is very difficult to remove. Compared with the affinity with water, the cotton fiber in filter paper has a weaker affinity with organic solvents.

Therefore, in most cases, paper chromatography takes the combined water in filter paper fiber as the fixed phase, while the mobile phase is dominated by organic solvents. When the mobile phase of the organic solvent passes through the sample, the water, and the organic phase will be continuously distributed, and then with the mobile phase constantly moving, the material of various components will be continuously redistributed, further separating and purifying the material. This use of filter paper is common in chemical laboratories. Both water and alcohol can be filtered.

Filtration and filter paper chromatography are two completely different concepts. Filter paper is actually a sieve, but its hole is relatively small, on the packaging box of filter paper have instructions, the size of the aperture. Generally use a medium – hole filter paper. Filter paper does not reach the molecular level unless the molecules are very large, such as high molecular weight polymers. So filtering is generally to remove mechanical impurities.

Chromatography is actually a method to diffuse different substances in the solution in the separation, generally speaking, because different substances on the filter paperdiffusion rate are not the same, with the passage of time, to different parts of the filter paper.

Using filter paper for chromatography is also called paper chromatography. If you know anything about the experiment of separating chlorophyll in biology class, you can use paper chromatography.

The Difference Between Filter Paper And Chromatography

How To Choose The Right Membranes Of Syringe Filter?

In general, the syringe filter is used before the sample solution enters the liquid chromatography. It filters out some particles that may block the system and the chromatography column. If impurities exist in the sample and solvent, it will not only damage the chromatographic instrument and column, but also have a great impact on the analysis results. The organic phase syringe filter has a good effect on protecting the chromatographic column and the chromatographic system from contamination, and also it can improve the sensitivity and accuracy of the analysis results. But how to choose filter membranes of different materials? HAWACH describes its membranes in details for your reference.

Nylon (NY)

The universal filter membrane is suitable for the filtration of most sample solutions and solvents. The filter membrane itself has hydrophobic properties, but it is also suitable for the filtration of aqueous solutions and organic solvents, and it is often used for the filtration of HPLC and GC samples and solvents.

Polytetrafluoroethylene (PTFE)

The hydrophobic filter membrane is suitable for the filtration of organic solvent media samples (including strong acids and strong bases) and organic solvents. Although it has a hydrophobic filter, it can also be made hydrophilic by adding ethanol and deionized water. It is used in filtration of all organic solutions, especially strong solvents that other filter membranes cannot tolerate.

Polyvinylidene fluoride (PVDF)

Hydrophobic filter membrane with very low protein adsorption, low resistance and fast filtration, is especially suitable for the filtration and sterilization of biological samples. In addition, it also has high chemical compatibility, suitable for the filtration of most media.

Cellulose acetate (CA)

Hydrophilic filter membrane has uniform pore size, high porosity, low resistance, fast filtration speed, and very small adsorption, which is mainly used to filter out particles and bacteria in biological samples and water-soluble samples.

Polyethersulfone (PES)

Hydrophilic filter membrane has low resistance, fast filtration speed, low protein adsorption, especially suitable for the filtration of viscous biological and cell tissue samples. In addition, it also has good permeability, suitable for rapid filtration of large volume of aqueous samples. Its applications cover the low protein adsorption and high drug compatibility, specially designed for biochemical, inspection, pharmaceutical and sterilization filtration devices.

Glass fiber (GF)

Universal pre-filtration membrane with a pore size of 1.0 μm, is suitable for high particle content or viscous sample filtration; compared with syringe filter without GF pre-filtration membrane, the processing capacity is increased by 2-4 times.

If the above cannot meet your requirement, please contact HAWACH team.

How To Choose The Right Membranes Of Syringe Filter?

ApplicationOf QuEChERS Method In The Detection

Concept of the QuEChERS method
QuEChERS is a new multi-residue sample processing method, and has the advantages of simplicity, convenience, economy, safety, and reliability, and is mainly suitable for detection of agricultural and veterinary drugs and papaverine in various fruits, vegetables, meat, hot pot bottoms. In recent years, research scholars have carefully analyzed the QuEChERS method and gradually expanded the application range of the method. Now, the QuEChERS method has become the preferred method for the detection of hundreds of agricultural and veterinary drug residues.

Composition of the QuEChERS method
When the technicians establish the QuEChERS method, they mainly choose three kinds of agents, namely extractant, dehydrating agent, and purifying agent. Grasping the composition of the QuEChERS method can serve as a theoretical foundation for the analysis of the advantages and the application of the QuEChERS method.

Advantages of the QuEChERS method
The QuEChERS method features a short detection cycle, simple operation and batch production, high accuracy, and precision. The feasibility of detecting samples is very high; there are fewer solvents and waste liquids generated, and the containers and utensils can be reused multiple times without causing resource waste while reducing application costs. In a word, the QuEChERS method is convenient, fast, reliable and safe.

Application in pesticide residue detection
The first application of the QuEChERS in the detection of pesticide residues in fruits and vegetables was in 2003. The method was simple to operate and low in cost. In order to conduct more in-depth research, the researchers tested the QuEChERS method on more than a dozen different foods. In the process of using the QuEChERS method, first, extract anhydrous magnesium sulfate and sodium chloride with acetonitrile, and then purify some fruits and vegetables. The chemical solution after purification is PSA and anhydrous magnesium sulfate. According to the experimental results, it is found that the pH and stability of these fruits and vegetables have changed due to the influence of chemical solutions, especially the stability has been significantly reduced.

Lehotay et al found in the experiment that when the pH value of the pesticide is 5, agriculture has a higher recovery rate, but it has no obvious relationship with the matrix of fruits and vegetables. Afterward, on this basis, it can be determined through experiments that there are two main methods of QuEChERS, namely, acetic acid buffered QuEChERS method with greater ionic strength and citrate buffered QuEChERS method with lower ionic strength. After the confirmation of many experiments, the acetic acid buffered QuEChERS method has been internationally recognized and has become the standard test method for fruits and vegetables. Both of these methods have played an important role in food safety.

Lee et al. used dry ice instead of buffer for extraction, which improved the recovery rate of pepper pesticide residues. Chen B et al. used chloroform instead of sodium chloride to solve the problem of low recovery in polarity analysis. Hu Jingrong improved the QuEChERS method, which has the characteristics of short extraction time, low solvent consumption, and high extraction efficiency, and improves the detection efficiency. The recovery rate of 18 pesticides in Chinese cabbage was 90% ~ 108%. The detection limit of the method is 0.02 ~ 55.75μg·kg-1, and the limit of quantification is 0.1 ~ 189.23μg·kg-1.

ApplicationOf QuEChERS Method In The Detection

120rmp Water Bath, Digital Display 10L-50L Rotary Evaporator

Lab rotary evaporator is mainly used in biopharmaceutical, chemical, pharmaceutical and other related fields for liquid concentration, crystallization, drying, separation, and solvent recovery.

Optional volumetric bottle:

 

10L rotovap,

 

20L rotary evaporator

 

,

 

50L rotary evaporator

 

.

Elegant appearance, simple design, easy to install and disassemble.

Features for RE120-W1/W2 series

 

lab rotary evaporator

1. The rotating speed of 20L rotary evaporator can reach 120rmp/min;
2. Temperature can reach 99°C for water bath;
3. Effective triple-flux coil condenser of Lab rotary evaporator increased evaporation process;
4. Integral bath of made of stainless steel with a protection layer which is safe to use and easy to clean;
5. Bath position can be lifted to adjust the position of the rotary bottle in the bath;
6. Seal ring of PTFE spring composite with the high vacuum;
7. Rotating bottle of 10L, 20L and 50L available;
8. The vacuum gauge is equipped as a reference to adjust accordingly;
9. Continuous receiving flask of 50L rotary evaporator with a discharge valve is equipped on this series to achieve continuous processing without changing the bottle;
10. W1 is for main and subsidiary condenser(double reflux) with hand rotary lifting type.
11. W2 is for the single condenser(triple reflux) with automatic lifting type.
12. RE120-W1 series Lab rotary evaporator is a cost-effective one to buy rotovap.

120rmp Water Bath, Digital Display 10L-50L Rotary Evaporator

Glass Molecular Distillation B1-Type

Wiped film molecular distillation technology is a high and new separation technology popular in developed countries in the world. Molecular distillation unit is widely used in extracting effective substances from natural substances, separating effective components from Chinese herbal medicine, and purifying polymer substances that are easy to decompose or polymerize. From the characteristics of 

vacuum distillation equipment for sale, glass distilling equipment can be used in industry, agriculture, marine industry and other fields of all aspects.

B1-type molecular distillation unit – external condenser type

The basic configuration is the same as the A1 Molecular distillation unit, adding the following items to it :
The cooling system of

 

wiped film molecular distillation

1. 1pcs of the exhaust valve to adjust the inside vacuum when it needed, excellent corrosion resistance.

2. One

 

glass distilling equipment

 

condenser, the material is high borosilicate glass 3.3, the inner wall of the glass-smooth, no defects.
3. 1 pcs of Collect bottle, beautiful shape, wiped film molecular distillation reliable quality.
4. 1 set of cooling circulator on vacuum distillation equipment for sale.
5. Gear pump discharge, convenient continuous discharge and make it easy for the operator to control the glass distilling equipment discharge speed.

Features of the glass distilling equipment manufactured by our company

1. The evaporator of wiped film molecular distillation has a large heating area and the material can be heated quickly, which can effectively improve the working efficiency.

 

2. Most of the vacuum distillation equipment for sale is made of high-quality glass, which is convenient for the experimenter to monitor the whole process of the experiment.
3. The magnetic sealing system is adopted on the

 

molecular distillation unit

 

to ensure the tightness of the system.
4. Provide appropriate heating and cooling system according to material requirements for wiped film molecular distillation.
5. The maximum temperature inside the molecular distillation unit system can reach more than 300 degrees, and the temperature can be accurately controlled.

Glass Molecular Distillation B1-Type

Introduction Of The Bottle-Top Dispenser

The instrument is divided into two types:

Internal and external. It is the use of a syringe plunger reciprocating movement and two one-way pistons liquid quantitative, directional movement, adding liquid. The internal loading type is composed of a liquid storage bottle and liquid feeders. The liquid feeder is a plastic screw cap, and the bottle Zhi Dao cap is connected to the syringe with the outlet pipe and the inlet pipe of the one-way piston to control the inlet and outlet of the test fluid.

On the top of the bottle cap, there is a gauge marked with a metal scale and a movable positioning sleeve to control the accuracy of the amount of added liquid. Connect a glass tube with a plastic tube on the cap to export the sample. At the end of the glass bend, there is a frosted nozzle to connect the plastic suction nozzle to control the flow rate. Among them, add a liquid hole on the bottle cap, its scale positioning weight stem core is metal, with hard plastic made of jagged positioning, in the adjustment of capacity more convenient and correct.

A liquid storage bottle is a glass bottle with a screw mouth for storing test liquid. The screw head matches the screw head of the bottle cap. External loading is to install the syringe with a one-way automatic piston outlet pipe and inlet pipe together with the positioning stem and positioning sleeve with calibration marks.

The utility model relates to a self-priming adjustable glass refuser, which is composed of a positioner mounted on a bottle body, a bottle cap, a graduated bar, a graduated bar, a syringe inside the bottle body, and a compression spring mounted between the pinching hand on the top of the syringe and the bottle cap. At present, there is no compression spring in the adjustable glass liquid feeder, so it needs to be operated by both hands when it is used.

When the injection needle is pressed, the pinching hand itself cannot be reset, so it is troublesome to use. The self-imbibition adjustable glass liquid feeder is equipped with a compression spring on the pin between the pinching hand and the bottle-top dispenser cap. When the pin is pressed down, the pinching hand can automatically reset under the action of the compression spring to complete the self-imbibition function.

The upper and lower single-phase piston of the liquid feeder has been precisely ground, screened and washed, and the sealing property of the syringe jacket and core is good, thus ensuring the accuracy of the liquid dosage.

The positioning lever is marked with a container scale. As long as the positioning sleeve is moved to the scale position of the required capacity, the liquid level of the marked quantity can be injected.

It has been proved that the use of quantitative and adjustable glass feeder is convenient, reliable, efficient, and can save a lot of time and cost of research and experiment. The main part of the instrument is made of hard glass and medical plastic PP, which can resist the general acid and alkaline liquid and can be high-temperature sterilized.

Introduction Of The Bottle-Top Dispenser

Introduction Of Chemistry, Biology, And Medical Pipette

As a useful instrument used to transport a measured volume of liquid, pipettes are widely used in chemistry, molecular biology research, and the medical tests too. From electronic pipettes to mechanical pipettes, you can find Hawach pipettes available in designs for various purposes with different levels of accuracy and precision.

The principle of the pipette is to create a vacuum above the liquid-holding chamber and release some vacuum to draw up and dispense liquid. The original pipette is made of glass which is used with aqueous solutions in the chemistry field. And the piston-driven air displacement pipettes are recommended as the most accurate and precise pipettes.

When you draw up liquid, you’d better dip the tip 3 to 5 mm below the liquid surface at a 90-degree angle. When you dispense, the best way is to hold the pipette at an angle of 45 degrees and place the tip against the side of the receiving vessel. If you have liquid in the tip, remember not to wipe off or blot the tip in any way, even from the exterior, as it will tend to attract and bleed off some of the liquid, with the poor result followed.

1. In terms of specifications: because the pipette has only a few fixed specifications, its use is limited. The pipette can be measured at will, so it is widely used. It also depends on the accuracy required by your experiment. Generally, you can choose a suitable pipette for analytical experiments.

2. On the scale: the pipette has a full scale, and the pipette only has a full scale. Pipettes are prone to errors during operation. The pipette is a one-time operation with fewer errors.

In terms of accuracy: a pipette with a scale is called a pipette, a glass tube is called a pipette, or a single standard pipette. The pipette is more accurate than a pipette. Especially when transferring a 20 or 25 ml volume of solution, it is necessary to take a graduated pipette several times to get a large error! Get it all in one go with a pipette!

3. Measure out and measure in: pipettes are used to accurately measure a certain volume of solution. A pipette is a meter-out instrument used only to measure the volume of the solution it emits. The pipette is a straight glass tube with a scale to know the volume of the liquid being measured. According to JJG196-2006, the type mark on the pipette: measuring type: In; measuring type: Ex; blowing type: Blow out.

A pipette is a precise pipette, which is more complicated to use; a pipette is a coarse pipette, which is simpler to use. So labs need to use them in different situations.

The use of pipettes is limited because they are available in a few fixed sizes. The pipette can be measured at will, so it is widely used. It also depends on the accuracy required by your experiment. Generally, you can choose a suitable pipette for analytical experiments.

Introduction Of Chemistry, Biology, And Medical Pipette

What are the low-level errors in the laboratory "jokes"?

Once, after extracting genomic DNA samples from human blood several times, I ran out of 70% ethanol and prepared a new bottle. As a result, DNA always disappears in the final step of washing. Oh my god, I made 70% ethanol into 70% water.

Brief Description Of Flash Column Chromatography

Flash column chromatography, also known as a flash column, is a fast separation method, but it does not sacrifice resolution as others have said.
In the general column chromatography process, it is usually accompanied by lateral diffusion, which will greatly reduce the resolution, so when walking the column, you should try to shorten the column chromatography time, especially to avoid the column overnight. The purpose of the flash column, that is, without sacrificing exchange efficiency (adsorption and desorption), use the fastest possible flow rate to reduce this lateral diffusion.

Flash column is not blindly pressurized to achieve the fastest flow rate; the flow rate has certain requirements. Regardless of the thickness of the column, the flow rate is generally adjusted to the rate of eluent reduction in the column is 2cm/min. This is an experience speed, adjustments to it should consider the balance of exchange efficiency and lateral diffusion.

Similarly, VLC (Vacuum Column Chromatography) is also a very good column chromatography technique. It uses TLC’s “multiple unfolding” techniques so that the two samples to be separated immediately overlap (on TLC). Get better separation. Unfortunately, such good technology, some people think that it is used for rough separation.

For synthetic and medicinal chemistry, it is often necessary to screen a large number of potential compounds in the early stage. Once the relevant active compounds are found, the compounds need to be mass-produced. At this time, the previous milligram-level synthetic preparation methods need to be modified and upgraded to develop a new set of synthetic purification preparation process to meet the clinical testing and application of a large number of later compounds. In this process, the process development of compound purification is a very important link; on the other hand, in the field of natural products, when high value-added monomers are found, how to obtain the target monomers in large quantities through purification means has been These are the core problems that need to be solved.

The process development mentioned above for purification and preparation, whether in the field of medicinal chemistry of natural products, is a problem that requires scientists to spend a lot of manpower and material resources to explore and solve. Generally, improvements are made in two aspects: 1. Change the synthetic route and try to use the recrystallization method to reduce the cost; 2. Use column chromatography above 100 grams to prepare purification technology.

In addition to the transformation of the synthetic route of the process, efficient column chromatography amplification technology is also a very critical step. In terms of the linear gradient method used, more solvent is consumed in practical applications. Therefore, the optimization of the method is urgently needed and very necessary. The success of the project is often closely related to this. Through the optimization of the method, we can isolate the most samples with the least time and solvent consumption.

Isocratic or step gradient methods are used for optimization. On the other hand, a column with higher column efficiency can help increase the sample load and speed up the separation.

Contains 5 simple steps:
TLC spot plate to test various mobile phase combinations; use a column with higher column efficiency; create a linear gradient method based on the TLC spot plate information; based on the results of the previous gradient method, use the gradient method to optimize; gradually increase the loading volume, to find the best sample loading range, while ensuring that the linear velocity of the method does not change.

This method can greatly reduce the time and solvent consumption, thereby reducing the cost of the final product. The use of the step gradient method greatly increases the efficiency of scale-up production, while reducing the consumption of solvent and time costs. On the other hand, for reversed-phase preparation, the optimization of the five-step method is also applicable.

Brief Description Of Flash Column Chromatography

Dragon Boat Festival

The Dragon Boat Festival is the fifth day of the fifth lunar month of each year in China, also known as the Duanyang Festival, Noonday Festival, May Festival, etc.; the Dragon Boat Festival is a traditional festival to commemorate Qu Yuan. Kaoru Atractylodes, Radix Angelicae Dahurica, the custom of drinking realgar wine. "Dragon Boat Festival" is one of China's national leg
al holidays and is included in the World Intangible Cultural Heritage List.

Dragon boat racing is an indispensable part of the Dragon Boats Festival, held all over the country. Dragon boats look like Chinese dragons. A team of people rows a dragon boat together. At the front of the boat, one team member beats a drum to encourage his teammates. It is said that the winning team will bring luck and happiness to the people of their village.

One of the customs of the China Dragon Boat Festival is eating Zongzi which is a kind of food made with sticky rice and is wrapped with reed or bamboo leaves. It has different shapes and fillings. In the northern part of China, people use red jujube as fillings. But in the southern part of China, people use beans, fresh meat, or egg yolk as fillings.

About The New Features Of Hawach HPLC Columns

Conventional C18 HPLC columns are operated under high-water mobile phase conditions for a long time, and the phenomenon of “column collapse” often occurs, causing the retention time and resolution of the analyte to drop sharply. The Hawach HPLC column is based on high-purity silica gel and is produced by a unique polar modification technology. By introducing polar groups, the surface is more easily wetted by water, thus effectively avoiding this phenomenon. In addition, Hawach HPLC columns perform equally well under high organic mobile phases, which can accelerate the desolvation process in LC-MS testing, thereby effectively improving the detection sensitivity of LC-MS. The mobile phase of the Hawach HPLC column can be used from a 100% aqueous phase to 100% organic phase, making method development easier.
 

Hawach HPLC columns not only retain the performance of traditional silica-based reversed-phase HPLC columns but also add some new features:
1. The surface of the packing has polar groups, suitable for separation under high water mobile phase conditions;
2. Enhanced retention of hydrophilic and polar compounds;
3. Unique selectivity and excellent resolution;
4. Reduce the interaction between basic compounds and residual silanol, and improve the symmetry of chromatographic peaks;
5. pH range 1.5-10, suitable for analysis of acid and alkali compounds.

Areas for Application
High performance liquid chromatography is particularly suitable for the separation and analysis of macromolecules, high boiling point, strong polarity, thermal stability compounds, as well as biological activities and a variety of natural products, which make up for the deficiency of gas chromatography. In recent years, with the rise of life science, the effect of high performance liquid chromatography is more obvious.

1. Change in retention time. The retention time may be changed due to the following reasons: if the column temperature change is large, it is required that the column be kept in a constant temperature state. If the isometric and gradient are not fully balanced, a mobile phase equilibrium column of at least 10 times column volume is required. If the column is contaminated, rinse the column daily.

2. Reduction in retention time. When the flow rate increases, it is best to check the pump and reset the flow rate. When the sample is overloaded, it is better to reduce the sample quantity.

3. Extension in retention time. When the flow rate drops, it may be pipeline leakage, at this time, it is best to replace the pump seal ring and remove the pump bubble. When the active point on the silica gel column changes, it is better to use a mobile phase modifier, such as triethylamine, or use alkali to purify the column.

4. The appearance of acromion or bifurcation. When the sample volume is too large, it is better to use the mobile matching sample, and the total sample volume is set to less than 15% of the first peak. When the column collapses or forms a short-circuit channel, it is better to replace the column with a weaker corrosive condition.

About The New Features Of Hawach HPLC Columns

Detail And Instruction Of SPE Cartridge

Solid phase extraction (SPE) cartridge is a kind of sample pretreatment device developed from the chromatography column for extraction, separation, and concentration. It is mainly used for the pretreatment of target compounds in various food, agricultural and animal products, environmental samples, and biological samples.SPE technology has been widely used in many GB/T and industry analysis standards.

SPE technology is based on the theory of liquid-solid chromatography and adopts selective adsorption and elution to enrich, separate, and purify the samples. It is a physical extraction process including liquid phase and solid phase. It can also be approximated as a simple chromatographic process. The more common method is to make the liquid sample solution through the adsorbent, retain the measured substance, then choose the appropriate strength of the solvent to wash away the impurities, and then use a small amount of solvent to quickly elute the measured substance, so as to achieve the purpose of rapid separation, purification, and concentration. It can also selectively absorb interfering impurities and allow the measured substances to flow out. Or at the same time adsorb impurities and the measured substance, and then use an appropriate solvent to selectively elute the measured substance.

Most common SPE cartridges are injection syringes made of polyethylene, which are equipped with two polypropylene or fiberglass stoppers filled with a certain amount of chromatographic adsorbent (filler). The upper end of the SPE cartridge is open, and the lower end is the outlet. The liquid is discharged from the outlet after it passes through the adsorbent. According to the space volume above the classical spe column packing, the SPE column can be divided into 1 mL, 3 mL, 6 mL, 10 mL, 15 mL, 20 mL, 30 mL, 60 mL, etc. There are also spe columns of special specifications produced according to specific application requirements. Viewed from the outside of the spe column, the classic SPE cartridges are similar to the syringe and is straight. Another spe column has a funnel at the top, which allows more samples to be loaded at one time during manual operation.

The sieve plate SPE cartridge is a new type of monolithic SPE cartridge. This product USES the secret technology exclusive process to C18 and C8 bonded silica gel packing for special treatment, so that it has high mechanical strength and toughness, no need to add polyethylene porous baffle as support in the SPE cartridge. The product of the secret proprietary technology “monolithic SPE cartridge is the earliest monolithic SPE cartridge in the domestic and foreign markets.
Solid phase extraction column without sieve plate

Product advantages of SPE cartridges :
1. The packing is stable and can be fixed well, without common problems such as loose packing.
2. The integrated design of the whole packing effectively avoids the “ditch effect”.
3. You can choose to pay with a particle size as low as 8-10, which greatly improves the efficiency of separation and the amount of carrying samples.
The capacity of spe column refers to the adsorption capacity of spe column filler. For the solid phase extraction column based on silica gel, its capacity is generally 1~5 mg/100 mg, that is, the column capacity is 1%~5% of the packing mass.

The capacity of spe column refers to the adsorption capacity of spe column filler. For the solid phase extraction column based on silica gel, its capacity is generally 1~5 mg/100 mg, that is, the column capacity is 1%~5% of the packing mass. The capacity of bonded silica gel ion exchange adsorbent filler is expressed in meq/g, that is, the capacity per gram of filler is X mg equivalent. The packing capacity is usually between 0.5 and 1.5 meq/g.

Column capacity must be considered when selecting spe column. Because the sample matrix we are dealing with is often complex, such as food, biological samples, and so on. In spe, the adsorbent will absorb impurities of the same nature while adsorbing the target compound. Therefore, when considering the column capacity should be the target compound plus the total amount of impurities that can be adsorbed should not exceed the column capacity. Otherwise, some of the target compounds may not be adsorbed during the sample loading process, resulting in a low recovery rate.

The use of SPE cartridge
The simplest spe can be done manually by attaching a syringe to the top of the spe column and squeezing the liquid out of the column. In addition, positive or negative pressure spe devices can also be used for spe operations on bulk samples. With the development of science and technology and the increase of sample quantity, more and more analytical laboratories begin to use automatic spe, especially multi-channel spe for batch sample processing.

Hawach has different types of SPE cartridges for your choice. If you like our product, don’t hesitate to contact us. We will reply as soon as we can. Looking forward to your reply.

Detail And Instruction Of SPE Cartridge

Advantages Processing Of Membrane Filter

Using the filter membrane device does not need flocculation chemical treatment, nor does it need evaporation separation, only need the pressure to separate the solid and liquid in the water, which is a major feature of the filter membrane treatment.

Application of drinking water
In MF, UF, NF, and RO, RO has not been used except for desalination applications. Almost all the salt is removed by RO, and the treated water is pure water that none of the salt has, even purer than distilled water, which of course cannot be used as drinking water. If it is to be used, it is necessary to add salt which is beneficial to human health, and there is no condition to meet this requirement.

The removal of salt by NF is second only to that of RO, but the removal rate is also very high. NF is generally used as soft water and is not suitable for drinking water due to the above reasons. Thus, the membranes used for water treatment should be MF and UF membranes. Such membranes are used primarily to remove colloids and plankton, to remove insoluble iron and manganese, and to remove fungi.

However, in order to prevent the bacteria from regenerating in the clear water, the sterilization process cannot be eliminated. Given the degree to which UF removes the molecular weight of the substance, it does not have the ability to remove organic solvents such as ozone and ethylene trihalide, which form a thin film on the membrane surface that may be removed in the future and maybe examined in the future.

In the type of membrane, external pressure hollow system or tube membrane is suitable for use. If the external pressure membrane is adopted, the raw water of the sedimentation tank can be directly connected with the membrane for treatment. In order to prevent membrane holes from being blocked, the floating substances in the original water should be removed before flowing into the membrane.

Drinking water application
The conventional treatment procedures of the water treatment plant are condensation, precipitation, and filtration. In the water treatment plant of membrane separation, the treatment procedures are simple and only need to be treated by the filter membrane device when the raw water meets the treatment conditions of the filter membrane. (when the water quality deteriorates, the conventional treatment or micro-screen treatment is still needed.)In terms of energy consumption, the filter membrane is used for full filtration. Since the pressure is increased through the filter membrane, the raw water pump still needs to be considered in increasing the pressure.

Advantages of processing
From the experience of using membrane in the past, the raw water (river water, reservoir water, and nutrient-rich lake water) used for drinking water was treated with MF membrane without coagulant, and compared with the conventional treatment of coagulation, precipitation and filtration with a coagulant, the former and the latter treated water quality was equal to or exceeded.

Membrane separation technology is used to provide only the necessary operating pressure for the raw water supply, and only a long running time is needed to flush the filter membrane, no other process. At present, there are various processes for coagulation, precipitation, and filtration water treatment, so the dosing rate cannot be set. In this case, it is easy to automate the operation of the membrane device and achieve unattended management, while it is not easy to automate routine processing.

Using a filter membrane water plant, the membrane device occupies a small area, and it is easy to reduce the area of the plant by half for the conventional treatment of the same amount of water. The remaining place can be equipped with an activated carbon treatment devices. As a result of the filter membrane water, plants can be unmanned, the staff living in the building and supporting facilities can be cut.

At present, the service life and price of the filter membrane are unknown, and the total cost is not easy to calculate. However, from the point of view of the membrane treatment of electricity and pharmaceutical costs are small, compared to the conventional treatment of high maintenance and management costs of the situation has great advantages.

As the membrane treatment does not require dosing, the amount of sludge is reduced, so it is easy to treat. Whether this is the case is still in the research stage, with no clear results.

Advantages Processing Of Membrane Filter