How to Choose Syringe Filter and Its Preparatory Work Before Use

Advantages of syringe filter

Easy to burst is one of the disadvantages of the traditional filters. The PTFE syringe filter is specially designed to withstand a burst pressure of up to 7bar. The edge of the filter is threaded to prevent slippage. The humanized design makes the operator handy. Stable membrane quality and zero difference from batch to batch ensure the consistency of analysis results. The clear specification mark avoids confusion, making it is suitable for a small amount of samples filtration in the laboratory.

It has low adsorption of samples, thus ensuring a large amount of recovery of small or high-value samples. The filter housing is made of polypropylene, welded by ultrasonic, and does not contain adhesive, so it will not contaminate the sample. With the precisely designed structure, it is able to guarantee to reduce the waste of samples, with smoother filtration, more rational internal space, and lower residual rate.

HAWACH lab syringe can effectively increase the flow rate and filtration capacity, and improve the filtration efficiency. With enhanced two-shot injection molding process, it can withstand higher operating pressure, increase the filtration speed, and make filtration easier. The ETO sterilization is more thorough and it does not contain pyrogen and RNase, it is safer and more reliable for biological experiments. Each filter is individually packaged for easy use.

Factors to be considered when choosing syringe filter

Three important issues need to be considered when getting a syringe filter.

1. First things come first. Quality is what we should consider first when we get any product. The syringe filter is expected to remove as much bacteria as possible without introducing other substances. 

　

2. Filter membrane. Many different kinds of filter membranes used in syringe filters are available. Both chemical compatibility and filtration time should be considered when selecting.

2.1 Filter membrane material (chemical compatibility): When choosing a filter membrane, first consider chemical compatibility, such as the resistance to organic solvent, acid, alkali and so on. 
2.2 The pore size of the filter membrane: For chromatographic column systems using 3μm or larger particle size fillers, 0.45μm needle sample filters or membranes can be used; for chromatography systems with fillers smaller than 3μm, or chromatographic systems involving the growth of microorganisms, it is recommended to use 0.2μm filter membrane.
2.3 Characteristics of the sample:
1) Hydrophilic samples: Available filter membranes are: mixed cellulose ester, polyethersulfone (PES), Nylon, etc.
2) Strongly corrosive organic solvents: generally use hydrophobic membranes, such as polytetrafluoroethylene membrane (PTFE), polypropylene (PP) and other materials. 
3) Protein solution: Choose a filter membrane with low protein adsorption, such as polyvinylidene fluoride membrane (PVDF).
4) Ion chromatography: Polyethersulfone (PES) membranes are generally considered to be more suitable for filtration of solutions with low inorganic ions.  

3. Specifications. After determining the filter and membrane, it is relatively easy to select specifications. When choosing a syringe filter, in addition to considering the above factors, the volume of the sample should also be considered (that is, what size sample filter should be selected): Usually, when the sample volume is less than 2ml, choose a 4mm diameter micro filter. If the sample size is between 2-10ml, choose a 13mm diameter filter; when the sample size is greater than 10ml, choose a 25mm diameter filter.

 

Preparatory work before the use of the syringe filter

In HPLC analysis, the particle size of the chromatographic column packing is small and it is simply blocked by impurity particles. Therefore, samples and solvents need to be filtered in advance to remove particulate contaminants and maintain the instrument. Ion chromatography, which is commonly used in environmental analysis, also requires no introduction of inorganic contaminants in sample pretreatment. 

After the filter element and the shell are completely cleaned and sterilized, the filter installation is necessary. First apply clean water or clean filtered liquid on the "O" ring of the filter element as a lubricant, and then carefully pierce the filter element straight into the socket plate at the bottom of the filter. If the 226 interface is used, the interface should be double-ear stab into the chassis. After the filter "O" ring enters the jack, screw it in clockwise to make both ears snap into the hole in the chassis. After installation, tighten the bolt seal.

After the filter device is over, the entire filter system must be completely flushed with clean water. After the entire filtration system is flushed and cleaned, the filtration operation can be carried out. Application areas of syringe filters are: filtration of aqueous and organic phase solutions in education and commercial research laboratories; education, quality inspection, quality control; chromatography and mass spectrometry sample preparation, ambient air, waste gas, and water quality analysis. It can be applied to food, beverage, pharmaceutical materials, products, semi-products testing and analysis, drug testing, medical seminars, life sciences seminars, microelectronics semiconductors, chemicals, cement/mineral analysis, etc.