The extraction is divided into liquid phase extraction (LLE) and solid phase extraction (SPE). SPE technology is a column chromatography separation process. The technology is a combination of liquid-solid extraction and column liquid chromatography. The combination of this technology improves the disadvantage of the low recovery rate of the analyses by traditional liquid-liquid extraction method, improves the recovery efficiency, makes the separation between the interferer and the analyses more effective, reduces the sample pretreatment process, and is simple to operate, time-saving and labor-saving.
Common method
SPE is the separation principle of selective adsorption and selective elution by liquid chromatography. The more commonly used method is to make the liquid sample solution pass through the adsorbent to retain the substance to be measured, and then select the appropriate strength of the solvent to flush the impurities, and then use a small amount of solvent to quickly elution of the material to be measured, so as to achieve the purpose of rapid separation and purification and concentration. It can selectively adsorb interfering impurities and let the measured substance flow out. Or adsorb both impurities and the material to be measured, and then use the appropriate solvent to selectively elution of the material to be measured.
SPE Technology Brief Introduction
2019年6月23日星期日
How to Choose Pipette — Product Performance
When purchasing pipette, the following aspects should be considered
1. High-quality performance
2. Unique Volume Control System
3. Consistent accuracy and repeatability
4. Reliable and durable
5. Human body engineering
1. High-quality performance
2. Unique Volume Control System
3. Consistent accuracy and repeatability
4. Reliable and durable
5. Human body engineering
The following will take the human body engineering of the pipette as an example, and outline the matters needing attention when purchasing the pipette.
The following points can be considered:
Firstly, the short distance of the thumb to complete a fluid transfer cycle means a higher degree of comfort.
Secondly, comparing the thumb force required by the same range of pipette to complete drainage (must press to the end), which is the key to affect comfort. The less the force, the less the risk of finger injury caused by long-term use.
Thirdly, loading and unloading suction head, the more labor-saving the better;
Fourthly, the weight of the pipette is moderate, too heavy will increase the burden of the hand, but too light also often means that the material may be unsatisfactory;
Fifthly, other auxiliary design, such as grinding design of shell and finger hook design, can help to further improve comfort.
Accuracy and repeatability
For the vast majority of users, it is both difficult and unnecessary to test product performance before purchase. Therefore, it is mainly based on the technical data provided by the manufacturer. But the following two points should be paid more attention to by users:
Firstly, do not easily believe the seller’s verbal commitment, must consult the manufacturer’s written materials;
Secondly, the brand which has a great influence on the global market of pipettes provides more reliable technical data.
Secondly, the brand which has a great influence on the global market of pipettes provides more reliable technical data.
Reliable and durable
In this respect, it mainly depends on the material used in the pipette. For the shell, it should have high impact resistance, corrosion resistance and low thermal conductivity (such as PVDF material); for the piston, there are mainly three kinds of materials in the market: stainless steel, ceramic and plastic. Stainless steel has good mechanical properties and long service life, but it is not suitable for strong acid and alkali transfer. Ceramics have high corrosion resistance, but poor mechanical properties. Of course, high-quality materials often mean higher prices, so we need to consider the factors of the purchase price and life.
Vacuum Filtration Operation
The vacuum filtration operation, that is, suction filtration, is an operation of reducing the pressure in the suction filter bottle by means of an air pump to achieve the purpose of solid-liquid separation. The device requires a Buchner funnel, a suction filter bottle, a hose, an air pump, a filter paper, and the like.
Principle: The suction pump is used to reduce the pressure in the suction bottle.
Purpose: To achieve the purpose of solid-liquid separation
Device
Brinell funnel, suction filter bottle, hose, air pump, filter paper
process
1. Install the instrument and check whether the connection between the Buchner funnel and the suction filter bottle is tight, and whether the air pump connection port is leaking;
2. Trim the filter paper so that it is slightly smaller than the Buchner funnel, but cover all the holes, and add distilled water to make the filter paper and the funnel tightly connected;
3. Turn on the air pump switch, pour the solid-liquid mixture, and start suction filtration.
4. After filtering, first take out the suction filter bottle and then close the suction pump.
5. Try to make the material to be filtered in the center of the Buchner funnel to prevent it from passing through the gap between the funnel and the filter paper.
Purpose: To achieve the purpose of solid-liquid separation
Brinell funnel, suction filter bottle, hose, air pump, filter paper
1. Install the instrument and check whether the connection between the Buchner funnel and the suction filter bottle is tight, and whether the air pump connection port is leaking;
2. Trim the filter paper so that it is slightly smaller than the Buchner funnel, but cover all the holes, and add distilled water to make the filter paper and the funnel tightly connected;
3. Turn on the air pump switch, pour the solid-liquid mixture, and start suction filtration.
4. After filtering, first take out the suction filter bottle and then close the suction pump.
5. Try to make the material to be filtered in the center of the Buchner funnel to prevent it from passing through the gap between the funnel and the filter paper.
Selection of Extraction Thimble
The extraction thimble is mainly applied in the lab experiment involved with Soxhlet Extraction to ensure complete extraction. There are three types of extraction thimbles available – cellulose extraction thimble, glass fiber extraction thimble, and quartz fiber extraction thimble.
Cellulose Extraction Thimble
The cellulose extraction thimble is made of high-quality cotton linters and seamless cellulose. It could be used in most Soxhlet extraction devices. One of its obvious features is the fast flow because of the high porosity. Also, its temperature tolerance is up to 100 degrees, based on outstanding mechanical strength and retention. Generally, it is applied in the determination of fats and lipids in the meat, dust particles in the air and oils.
Glass Fiber Extraction Thimble
The glass fiber extraction thimble is made of borosilicate glass fibers. Compared with the cellulose one, it could undertake the temperature above 120 degrees and be used for the strong acidic solutions or gas. Thus, it is mainly applied in the detection of smoke and dust, extraction of the strong acidic solutions, and emission controls.
Quartz Fiber Extraction Thimble
The quartz fiber extraction thimble is made of quartz or silica fibers. Its temperature resistance is even much higher than the glass fiber one, which could be up to 900 degrees. It could be used in air sampling and exhaust gas monitoring.
Calibration Specification for Bottle-Top Dispenser
The bottle-top dispenser is widely used in the chemical and biological industry for the acid, alkali, saline solutions, and organic solvents with fast speed and high accuracy. Along with the increasing demand for the bottle-top dispenser, the calibration for it is getting more inevitable and necessary.
Conditions for Calibration
Before the calibration is conducted, the environmental conditions need to be guaranteed in the first place. The ambient temperature should be maintained as (20±5)℃, which changes no more than 1℃ per hour. Meanwhile, the relative humidity needs to be kept from 40% to 70% and changes less than 10% per hour. Also, the power supply should be (220±22)V.
Under GB6682-2008 Analysis of Experimental Water Specifications And Test Methods, distilled or deionized water is the required water for calibration.
Before the calibration is conducted, the environmental conditions need to be guaranteed in the first place. The ambient temperature should be maintained as (20±5)℃, which changes no more than 1℃ per hour. Meanwhile, the relative humidity needs to be kept from 40% to 70% and changes less than 10% per hour. Also, the power supply should be (220±22)V.
Under GB6682-2008 Analysis of Experimental Water Specifications And Test Methods, distilled or deionized water is the required water for calibration.
Factors to Be Evaluated
During the calibration for the bottle-top dispenser, two decisive factors affect the final calibration result, which is capacity calibration value and measurement repeatability. Usually, the calibration point is at 10%, 50% and 100% volume scale of the dispenser’s capacity. Each calibration point needs to be measured for 6 times repeatedly so that the workers could obtain an accurate capacity error coefficient in the end.
During the calibration for the bottle-top dispenser, two decisive factors affect the final calibration result, which is capacity calibration value and measurement repeatability. Usually, the calibration point is at 10%, 50% and 100% volume scale of the dispenser’s capacity. Each calibration point needs to be measured for 6 times repeatedly so that the workers could obtain an accurate capacity error coefficient in the end.
Normally, the internal of recalibration for the bottle-top dispenser is supposed to be less than a year.
Hawach Scientific Qualitative Filter Paper
Hawach Scientific product quality in strict accordance with ISO9001:2000 quality system certification procedures, and from now on we have exported to more than 120 countries.
Overview of qualitative filter paper, analysis laboratory commonly used filter paper as a filter medium, so that the solution and solid separation.
Qualitative filter paper generally has a large amount of residual ash, which is only used for general qualitative analysis and filtration of precipitation or suspended substances in solution, not for quality analysis.
The types and specifications of qualitative filter paper are basically the same as those of quantitative analysis filter paper, which means fast, medium and slow speed. Instead, the characters of fast, medium and slow speed are printed. However, when the filter paper is not used for quantitative and qualitative analysis on the filter paper box, it should be noted that:
(1) The general use of natural filtration, the use of filter paper and the ability to trap solid particles, so that the liquid and solid separation;
(2) As a result of the filter paper mechanical strength and toughness are less as far as possible with the method of filtration, such as must accelerate the filtration speed, in order to prevent filter failure, in order to prevent filtering through the air pump filtration, according to the size of the suction in the funnel stack 2 ~ 3 layers of filter paper, in the vacuum filtration, in the leakage. At first, pad a layer of dense press cloth, and then put filter paper to filter;
(3) Filter paper had better not filter hot concentrated sulfuric acid or nitric acid solution.
Products classify
1. Standard Grades Qualitative Filter Paper
BIO-1 , Particle Retention 11um , Ash Content 0.1% , 84g/m2
BIO-2 , Particle Retention 8um , Ash Content 0.1% , 84g/m2
BIO-4 , Particle Retention 20um , Ash Content 0.1% , 84g/m2
BIO-5 , Particle Retention 2.5um , Ash Content 0.1% , 84g/m2
BIO-6, Particle Retention 3um , Ash Content 0.1% , 84g/m2
2. Wet Strengthened Grades
These extremely strong filter papers have a high wet strength due to the addition of a small quantity of chemically stable resin.
BIO-91 ,Separating Property PbSO4 , Filtration Seconds 35-70 , pore size 10um ,Basis Weight 84 g/m2 ,Ash Content 0.13%.
BIO-113 ,Separating Property Fe(OH)3 , Filtration Seconds 35 , pore size 30um ,Basis Weight 64 g/m2 ,Ash Content 0.13%.
Specification :
Diameter available : 70/90/110/125/150/180mm.
Sheet : 600×600,650×650,800×800,850×850,900x900mm.
Hawach Scientific Qualitative Filter Paper
Overview of qualitative filter paper, analysis laboratory commonly used filter paper as a filter medium, so that the solution and solid separation.
Qualitative filter paper generally has a large amount of residual ash, which is only used for general qualitative analysis and filtration of precipitation or suspended substances in solution, not for quality analysis.
The types and specifications of qualitative filter paper are basically the same as those of quantitative analysis filter paper, which means fast, medium and slow speed. Instead, the characters of fast, medium and slow speed are printed. However, when the filter paper is not used for quantitative and qualitative analysis on the filter paper box, it should be noted that:
(1) The general use of natural filtration, the use of filter paper and the ability to trap solid particles, so that the liquid and solid separation;
(2) As a result of the filter paper mechanical strength and toughness are less as far as possible with the method of filtration, such as must accelerate the filtration speed, in order to prevent filter failure, in order to prevent filtering through the air pump filtration, according to the size of the suction in the funnel stack 2 ~ 3 layers of filter paper, in the vacuum filtration, in the leakage. At first, pad a layer of dense press cloth, and then put filter paper to filter;
(3) Filter paper had better not filter hot concentrated sulfuric acid or nitric acid solution.
Products classify
1. Standard Grades Qualitative Filter Paper
BIO-1 , Particle Retention 11um , Ash Content 0.1% , 84g/m2
BIO-2 , Particle Retention 8um , Ash Content 0.1% , 84g/m2
BIO-4 , Particle Retention 20um , Ash Content 0.1% , 84g/m2
BIO-5 , Particle Retention 2.5um , Ash Content 0.1% , 84g/m2
BIO-6, Particle Retention 3um , Ash Content 0.1% , 84g/m2
2. Wet Strengthened Grades
These extremely strong filter papers have a high wet strength due to the addition of a small quantity of chemically stable resin.
BIO-91 ,Separating Property PbSO4 , Filtration Seconds 35-70 , pore size 10um ,Basis Weight 84 g/m2 ,Ash Content 0.13%.
BIO-113 ,Separating Property Fe(OH)3 , Filtration Seconds 35 , pore size 30um ,Basis Weight 64 g/m2 ,Ash Content 0.13%.
Specification :
Diameter available : 70/90/110/125/150/180mm.
Sheet : 600×600,650×650,800×800,850×850,900x900mm.
Hawach Scientific Qualitative Filter Paper
2019年6月20日星期四
How to Select Different Kinds of Syringe Filter
Syringe filter is a kind of filter connected to the front of the syringe. When the experimenters deal with the chromatographic samples with syringe filter, they should pay attention to avoiding bringing impurities in the process of filtration. One reason for the appearance of such impurities may be that the particulate matters removed from the shell material or filter membrane is going into the filtrate. Therefore, the materials of the filter membrane and shell are very important to experiments, and different types of filter membranes are suitable for different types of samples.
When handling hydrophilic samples, the experimenters should select hydrophilic membranes, which has an affinity to water and is suitable for filtrating solvents in which water is regarded as a substrate. The available filter membranes are mixed cellulose esters, etc.
When handling strong corrosive organic solvents, the experimenters generally use hydrophobic membranes, such as PTFE, polypropylene (PP) and other materials.
When the samples are referred to the protein solutions, people will choose the membranes with low protein adsorption, such as PVDF membrane.
And it is generally considered that PES membrane is more suitable for the filtration of solutions with low inorganic ions.
Besides the above factors we have mentioned, people usually consider about the volume of samples. Different volumes of samples mean choosing different sizes of syringe filters.
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