PFA is widely used in semiconductors, geology and biotechnology due to its excellent chemical properties, and it is crucial to clean PFA utensils effectively to avoid cross-contamination.
The initial cleaning of new PFA labware (including all types of bottles) and cleaning procedures after each use vary from application to application, especially if the PFA labware is used for sample preparation or sample pre-treatment for trace metal analysis.
It should be noted that the cleaning method mentioned below is not the only effective cleaning method for PFA vessels, and each lab technician can use this method as a basis and improve it with their own needs to suit the current experimental use. The following methods are applicable to PFA as well as FEP vessels.
CAUTION: Never use brushes or abrasives to clean any PFA labware – these can cause surface scratches that can leave metallic and organic contaminants and prevent effective cleaning.
A, Initial cleaning of PFA labware before first use after purchase
a) Applicable objects: Conventional laboratory, Nanjing Binzhenghong and Savillex all kinds of PFA vessels
Procedure: 1. Thoroughly rinse the interior and exterior of the labware with deionized water (DIW) to remove any surface contamination
2. If desired, a more thorough cleaning can be achieved by soaking in a solution of a mild alkaline detergent (e.g. 1% Micro 90) and heating to 100°C to remove any organic residue. Allow to cool and rinse well with DIW.
b) Applicable objects: Trace metal laboratory, Nanjing Binzhenghong and Savillex Purillex Bottle PFA reagent bottle.
PFA reagent bottles are commonly used as containers for solutions and standards in trace metal laboratories. pfa reagent bottles are also used as collection bottles for acid purification systems. Additional reagent bottles are often used to store high purity acids produced from CH. When used for ultra trace (low PPT level) metals, such as storage of high purity acids, a thorough clearing of the ho before first use should be performed, as recommended below:
(PFA Reagent bottle 30ml- 4000ml)
1. rinse the bottle thoroughly with deionized water (DIW)
2. fill with a mixture of 2% high purity HNO3 + 1% high purity HF (if HF is not available, use HNO3 alone) and tighten the cap to seal
3. store the bottle at 50°C for at least 48 hours (preferably 7 days)
4. empty the bottle and rinse thoroughly with DIW
5. repeat steps 2-46. complete the cleaning and the bottle is now ready for for ultra trace use
B, PFA labware cleaning after each use
Target: PFA vials for geochemical sample digestion
The digestion of geological samples prior to isotopic analysis by TIMS or MC-ICP-MS is one of the most challenging ultra-trace applications for PFA laboratoryware. A rigorous cleaning procedure must be performed for the PFA vials used in the digestion step. Each laboratory has its own cleaning procedures and they are all slightly different. Below are two typical examples of PFA vial and cap cleaning procedures.
a) Method A
1. Clean the vial mechanically by gently wiping the inside of the vial with a solution of clean laboratory paper and an acidic cleaner/degreaser (e.g., 2% Citranox) to remove digestive residue – be careful not to scratch the surface
2. Immerse the vials in 50% aqua regia in the vial cleaning system. Heat to approximately 90°C for at least 24 hours
3. Remove from the vial cleaning system and repeat step 2, but this time use DIW for soaking
4. Remove from the vial cleaning system and repeat step 2, but this time use 50% HNO3 for soaking
5. Repeat step 3
6. Remove from tank and rinse thoroughly with DIW
Note: Under certain conditions, cleaning PFA with HCl and HNO3 at high temperatures can cause white deposits to form on the PFA surface. This may result in a cloudy appearance of PFA. To avoid this, use HNO3 instead of aqua regia.
b) Method B
1. Clean the vial mechanically by gently wiping the interior with lab-clean paper – be careful not to scratch the surface
2. Immerse the vial in a dilute solution of a mild alkaline cleaner (e.g., 1% Micro 90) from the Vial Cleaning System. Heat to 100°C to remove any organic residue. Allow to cool and rinse with DIW
3. Immerse the vials in 6M HNO3 in the vial cleaning system. Heat to approximately 100°C for 6 hours 4. Remove from vial cleaning system and rinse thoroughly with DIW 5. Add 3-4 mL of high purity 6M HNO3 to each vial and tighten cap to seal. Place on a graphite corrosion resistant electric heating plate and heat gently until needed (the longer the better – even days if possible)
6. Empty and rinse thoroughly with DIW
For PFA labware used in medical/biopharmaceutical applications, not only thorough cleaning but also strict sterilization is required. The cleaning and sterilization of PFA labware for medical/biopharmaceutical use can be found in the following protocols.
C, PFA labware cleaning and sterilization for medical/biopharmaceuticals
a) Initial Cleaning: Initial cleaning of medical/biopharmaceutical PFA labware 1. Thoroughly rinse the interior and exterior of the labware with DIW to remove any surface contamination 2. If desired, a more thorough cleaning can be achieved by soaking in a solution of a mild alkaline detergent (e.g., 1% Micro 90) and heating to 100°C to remove any organic residue. Allow to cool and rinse clean with DIW.
b) Sterilization: Sterilization of medical/biopharmaceutical PFA labware
1. Place the labware in the autoclave, remove the sealed lid and leave it open (this is important to avoid damage to the labware)
2. Autoclave at 121°C for 90 minutes and allow to cool Note: PFA labware can be sterilized by all conventional methods except gamma radiation and electron beam.