Institute of Epidemiology and Microbiology, Chinese Academy of Preventive Medicine
Deputy Director of Disinfection Testing Center, Chinese Academy of Preventive Medicine
Oxidation potential water (also known as strongly acidic water, acidified potential water, strongly acidic electrolyzed water, acidic oxidation potential water, functional water, etc.) Water, this water has a strong oxidizing ability and quickly kills microorganisms. The research on oxidative potential water began in 1987, and was independently developed by Japan as a fungicide with a significant effect on methicillin-resistant Staphylococcus aureus (MRSA). After years of research, people's understanding of it has continued to deepen, and its sterilization effectiveness, safety, and no residues are beneficial to environmental protection. The advantages of it have been recognized, and it has been used in the medical field for hand disinfection and endoscope cleaning. Disinfection, disinfection of hemodialysis equipment, disinfection of the environment, and treatment of wounds such as bedsores. Since 1995, the oxidation potential water generator entered the Chinese market and was quickly recognized by Chinese counterparts, and was used in some hospitals to sterilize medical equipment in endoscopes, dental drills, operating rooms, and supply rooms. At present, domestic Beijing and Shenyang , Shanghai, Anhui and other places have developed such products. And passed the health license of the regional health administrative departments. The development and application of this product is of great significance for preventing nosocomial infections and controlling the pollution of disinfectants to the environment.
1. Physical and chemical properties
Oxidation potential water is a colorless and transparent liquid with chlorine odor, its redox potential is between 1050-1180mV, and the available chlorine content is generally 10-50mg/L. Under the conditions of room temperature, airtight and dark, it is relatively stable and can be stored for 1-2 months. However, under the conditions of room temperature exposure, it is unstable and can be decomposed into tap water by itself, so it is not suitable for long-term storage. . Hayashihara in Japan analyzed the water quality of the oxidation potential water, and showed that the pH value, redox potential, Na ion, active oxygen, etc. in the oxidation potential water were significantly different from those of tap water and alkaline ionized water.
2. The principle and method of oxidation potential water production
Miyake Haruhisa (1997) and Ogawa Toshio (1995) gave a more detailed description of the principle of oxidative potential water generation and the role of the diaphragm.
Potential oxidation water is obtained by electrolyzing tap water with 0.05% NaCl through a combined electrolytic cell with an ion diaphragm in an oxidation potential water generator. Since the ion diaphragm separates the anode side and cathode side of the electrolytic cell, (salt) water is dissociated into H+ and OH- by electrolysis, and OH- is combined with the anode side or gains electrons to become OH, with the reaction of 4OH→2H2O+O2 , 4OH becomes water and oxygen, and 4H+ remains in the electrolytic cell on the anode side, and H+ accumulates in the anode cell separated by the diaphragm, so the water obtained from the anode cell will be acidic. The anode generates chlorine gas from chloride ions (Cl-), and then further reacts with H2O to generate hydrochloric acid and hypochlorous acid (HOCL), so that the water obtained from the anode tank contains 10-50mg/L of available chlorine.
In addition, H2O is also electrolyzed into oxygen (O2) and hydrogen ions at the anode. As a result, the pH value of the water obtained in the anode tank is below 2.7, the effective chlorine concentration reaches 10-50 mg/L, and the dissolved oxygen and redox potential increase significantly. , generally between 1050-1180mV.
3. Killing effect on microorganisms
1. Killing effect on bacterial propagules
Oxidative potential water can quickly kill various bacterial propagules. Zhi Yeyan (1995) reported that when the ORP value was 1100mV and the pH value was 2.60, oxidizing potential water for 30 seconds and 1 minute had a significant effect on Staphylococcus aureus, Escherichia coli, Typhimurium, Pseudomonas aeruginosa, Staphylococcus aureus ( MRSA) killing rates were 99.99% and 100%, respectively. Reports from the Japan Food Hygiene Inspection Center and Hayashihara Masa have shown that the oxidation potential water has a rapid killing effect on Escherichia coli, Salmonella, Pseudomonas aeruginosa and MRSA. Li Xinwu et al. (1996) reported that under the condition of 20℃, the ORP value was 1127mV, the pH value was 2.6, and the oxidative potential water with the available chlorine content of 20-30mg/L was treated for 15 seconds. The kill rate was 100%. Horita Kunimoto (1999) reported that oxidative potential water was sensitive to methicillin-sensitive Staphylococcus aureus MRSA, Staphylococcus epidermidis, Enterococcus faecalis, Escherichia coli 0157:H7, Klebsiella pneumococcus, Pseudomonas aeruginosa, Salmonella typhi, The killing time of Serratia and Vibrio parahaemolyticus was less than 10 seconds.
2. Killing the virus
(1992) compared the inactivation of various viruses by using oxidative potential water, and proved that oxidative potential water has a good inactivation effect on viruses.
Li Xinwu et al. (1999) compared the destruction effect of oxidative potential water prepared by oxidative potential water generators from six Japanese manufacturers on the antigenicity of HBsAg. The results showed that the ORP value of the oxidative potential water was between 1081-1174mV and the pH was 2.3-2.6 Between 10 and 50 mg/L of available chlorine, the antigenicity of HBsAg can be destroyed for 30 seconds. The report of Nian Weidong et al. (1999) showed that the normal saline containing the serum of patients with hepatitis B was injected into the biopsy hole of the gastroscope, and disinfected with an automatic ultrasonic atomizing endoscope disinfection machine filled with oxidized potential water for 3 minutes. The results of HBV DNA detection by hybridization and PCR were negative. The above results show that the oxidation potential water has a good inactivation and destruction effect on the virus itself, HBsAg and nucleic acid.
3. Killing effect on fungi or yeast
Zhi Yeyan (1995) reported that the oxidation potential water has a good killing effect on yeast, and the killing rate of Rhodstorula sp and Candida albicans in 30 seconds is greater than 99.90%. Horita Kunimoto (1999) reported that the oxidative potential water can kill Candida albicans, Aspergillus terreus and Trichesperon in less than 15 seconds. Domestic Yi Jianyun (1998) proved that the oxidation potential water can kill 100% of Candida albicans for 5min.
4. Killing effect on bacterial spores
Li Xinwu (1996, 1999) reported the killing effect of oxidative potential water on the spores of Bacillus subtilis black var. (ATCC 9372). In the absence of peptone, 100% of the spores can be killed by oxidizing potential water for 10-20 minutes. Deng Xiaohong (1998) and Yi Jianyun (1998) also reported the same results respectively.
There are currently two theories about the sterilization mechanism of oxidative potential water. One is based on Berking's theory on the relationship between pH and ORP in the water environment and the survival of microorganisms. It is believed that microorganisms cannot survive under the conditions of low pH and high ORP. The sterilization mechanism of survival, oxidation potential water is mainly due to low pH value and high ORP value. Another point of view is that hypochlorous acid plays a major role, which is mainly based on: 1 The pH value and ORP value of strongly alkaline water are outside the range of microbial survival, but only show a weak bactericidal effect. 2. The application of strong alkaline water and oxidation potential water will reduce the ORP value and increase the pH value, and still maintain a high bactericidal activity. 3 When the pH value and ORP value do not change, the bactericidal activity of the oxidizing potential water is obviously decreased when the available chlorine is reduced. 4 Even if the oxidizing potential water is not in direct contact with microorganisms, it can kill microorganisms. 5 The oxidation potential water obtained by replacing sodium chloride with sodium sulfate has only weak bactericidal activity. Li Xinwu (1996) studied the bactericidal mechanism of oxidative potential water on microorganisms. Through electron microscope observation, it was found that the spores of Staphylococcus aureus and Bacillus subtilis black var. Swelling, rupture, and promoting the exudation of cellular contents, this phenomenon is consistent with the results of chlorination confirmed by Friberg (1957) (Figure 2-6)
Li Xinwu et al. (1999) also found that the 2000-fold diluted hydrochloric acid solution and sodium hypochlorite were prepared into a solution with the same pH value, ORP value and effective chlorine content as the oxidation potential water, and distilled water and sodium hypochlorite were prepared The solution with the same effective chlorine content as the oxidation potential water has the same killing effect on Staphylococcus aureus as the oxidation potential water, which proves that the main bactericidal factor in the oxidation potential water is available chlorine. Shimizu Yoshihide believes that the sterilization mechanism of oxidative potential water may hinder the activity of enzymes. By measuring the effect of oxidative potential water on enzymes, it was found that the activity of various metabolic enzymes can be lost when they react with oxidative potential water.
Since the main bactericidal factor in the oxidation potential water is available chlorine, and the available chlorine content in the water is low, in the presence of organic matter, it has a significant impact on the killing of microorganisms. Li Xinwu et al. (1996, 1999) found that adding 10% calf serum or 1% peptone to the spore suspension of Bacillus subtilis var. black, and oxidizing potential water for 20 minutes, the killing rate decreased from 100% to 100%, respectively. 19.5% and 59.54%. However, adding or not adding 1% peptone to the bacterial propagule suspension has no effect on its killing effect, and the killing rate of 30 seconds is 100%. Adding 25% and 50% calf serum to the Staphylococcus aureus suspension containing 1% peptone for 30 seconds, the killing rates of the two bacterial suspensions by oxidation potential water were 100% and 99.97%, respectively. It shows that the increase of organic matter has an influence on the effect of oxidation potential water to kill Staphylococcus aureus. Zhi Yeyan (1995) studied the effects of 6 kinds of organic compounds, including human serum, yeast, horse serum, and bovine serum, in different concentrations of oxidative potential water on Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Klebsiella pneumoniae. 11 kinds of bacteria killing effect. It shows that all kinds of organic matter have influence on the effect of oxidation potential water to kill different bacteria. With the increase of organic matter concentration, the bactericidal effect decreases. Except for human serum, when the concentration of the other five organic substances is the same, the bactericidal effect time is prolonged, and the bactericidal effect of the oxidation potential water is the same.
Bo Yuxia (1999) reported that the effect of oxidative potential water in killing Bacillus subtilis var. niger spores increased with the increase of the action temperature. Under the conditions of bactericidal action temperature of 10℃, 20℃ and 30℃, the effect of 10 minutes of killing The killing rates were 72.59%, 94.09%, and 99.69%, respectively, and the killing rates at 20 minutes were 99.31%, 99.99%, and 100%, respectively. It can be seen that with the increase of temperature, the sterilization ability of oxidative potential water increases. This performance is consistent with the performance of chlorine-containing disinfectants. Zhi Yeyan (1995) reported the killing effect of oxidative potential water on 9 bacteria including Staphylococcus aureus (MRSA), Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae at different temperature. Under the conditions of 4 ℃, 10 ℃, 20 ℃, 37 ℃ and 56 ℃, they have the same bactericidal effect for different time respectively.
3. Storage conditions
Li Xinwu et al. (1996) studied the effect of four storage conditions on the pH value and ORP value of oxidative potential water. The dynamic changes of its pH and ORP values were measured at different times. The results showed that under the open condition of room temperature, the pH value increased with time, and the pH value increased from 2.5 to 2.9 in 2 days, and increased to 3.0 in 14 days. The ORP value decreased with time. The ORP value decreased from above 1100MV to below 1000MV after 3 days, and decreased to 450MV after 7 days. The other three condition values were relatively stable, and basically did not change within 21 days. Gao Zheping (1999) reported that the oxidation potential water can be stored for 1 day and 4 days respectively in open containers with a diameter of 12CM and 2.8CM at room temperature of 25 ℃, maintaining its ORP value above 1000MV and pH value of 3 , The effective chlorine content is 30MG/L. With the extension of time, the pH value of the oxidation potential water stored in an open container with a diameter of 12cm is stable at 3, and the ORP value and effective chlorine continue to decrease. The ORP value at 7 days was 550MV, and the available chlorine was undetectable.
4. Sodium chloride concentration
Shimizu Yoshihide (1994) studied the relationship between the concentration of sodium chloride added in tap water and the pH, ORP value and available chlorine in the oxidation potential water. The PH value increases, while the content of ORP and available chlorine decreases, which can lead to a decrease in the bactericidal effect.
5. PH and ORP
Previous studies believed that the bactericidal effect of oxidative potential water may be related to the pH and ORP values. The increase of PH value and the decrease of ORP value can reduce the biological killing ability, while some recent studies have shown that the main factor of oxidative potential water sterilization is effective. Chlorine, but no available chlorine was measured. Only measuring the pH value to generate the ORP value will give people an illusion that the increase of the pH value and the decrease of the ORP value will lead to the weakening of the bactericidal ability. In fact, when the pH value increases and the ORP value decreases, the available chlorine concentration also decreases. Therefore, the bactericidal ability decreases. Since the content of available chlorine in the oxidation potential water is low and unstable, the conventional quantitative method is difficult to measure, so it is feasible to use the PH value and ORP value as an indirect indicator to judge whether the oxidation potential water has reached the bactericidal ability.
6. Water hardness
Due to the different hardness of tap water in different countries and regions, during the electrolysis process, it will affect the quality of the oxidation potential water, reduce the life of the electrode, and affect the disinfection effect. Therefore, when the hardness of tap water is high (over 100MG/L), it should be A soft water treatment device is added between the oxidation potential water generator to ensure the quality and disinfection effect of the oxidation potential water.
Because the oxidation potential water has the characteristics of fast killing microorganisms, good effect, no corrosion to stainless steel, no irritation to skin and mucous membranes, and it is quickly restored to tap water after use, leaving no residual poison, which is beneficial to environmental protection. Objects, methods of use, various occasions, and reasonable use can achieve better disinfection effect. It can be widely used in medical and health care, epidemic prevention, food processing, agriculture, animal husbandry, tourism, etc.
Medical and hygiene disinfection
(1) Cleaning and disinfection of hands Oxidized potential water was approved by the Ministry of Health and Welfare of Japan in 1997 as a cleaning and disinfectant for hands. When washing hands with oxidative potential water, the conditions of use of the oxidative potential water can be changed according to the degree of contamination of the hands and the desired degree of cleanliness. For daily hand washing, such as before meals, after toilets, and after general cleaning, it can be washed with oxidative potential water for 15 seconds. For hygienic handwashing, such as infusion drip operation, disinfection of works and other medical actions, and before sterilization operations such as catheter insertion, after the use of equipment contaminated by bodily fluids, isolation of the entry and exit of wards and other clean spaces, etc. It can be washed with oxidative potential water for 60 seconds, and a better disinfection effect can be achieved. In Japan, the centralized treatment inpatient building is currently equipped with an automatic oxidation potential water supply system, which makes it possible for medical workers to use the oxidation potential water to wash their hands frequently, and has achieved remarkable results in preventing cross-infection among medical workers. And it solves the problem of damage to opponents that occurred frequently when using disinfectant to disinfect hands in the past.
(2) Disinfection of wounds and wounds Oxidized potential water has been recognized by the World Health Organization (WHO) in 1994 as a disinfectant for wounds and wounds to prevent infection, and has been applied in Rwanda peacekeeping operations. In 1996, the Burn Department of Jianyang City People's Hospital of Sichuan Province performed 256 bacterial cultures on 78 burn patients, and a total of 38 bacterial strains were detected. The first three bacteria with higher detection frequency were Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli in turn. No bacterial growth was found in the liquid after cleaning the wound with oxidative potential water and the cleaned wound after bacterial culture. After treatment with oxidative potential water, the exudate of superficial second-degree and deep second-degree burn wounds was significantly reduced, the inflammatory reaction at the wound edge was reduced, the wound surface was clean, the necrotic tissue of deep second-degree burns was rapidly dissolved, the skin growth was accelerated, and the wound surface was healed compared with conventional simple debridement. Compared with the treatment, it can heal 4 days earlier. After the application of oxidative potential water to the third-degree burn wound, the scab will be removed earlier, and the granulation will be formed well, which is beneficial to the early skin grafting. After debridement, the patients generally have no abnormal reaction, asexual to the wound, and no other adverse reactions. He Xiaohong (1999) used oxidative potential water to rinse and disinfect the perineal wounds of 350 postpartum women, and then rinsed with warm boiled water and then applied gentamicin injection or 75% ethanol or 1/2000 benzalkonium bromide solution. The results were compared, and the results showed that the former was significantly better than the latter. After the former was used for rinsing and disinfection, there was no case of wound infection, the wound healing time was significantly shortened, and the patient did not feel any sense of ignorance.
(3) Disinfection of endoscopes The research on disinfection of endoscopes with oxidative potential water began in 1993. As a special study of the Ministry of Health and Welfare of Japan, this study was conducted by 2 clinical experts, 2 infectious disease experts and 1 endoscopic The lens manufacturers formed a team to objectively and impartially study the effect of oxidizing potential water. Pollution. A comparative study was made on the disinfection effects of manual cleaning, special disinfection devices, and oxidative potential water. The results showed that as long as the oxidative potential water was used correctly, a safe, rapid and strong disinfection effect could be obtained, which was suitable for the cleaning and disinfection of endoscopes ( Table 4, Table 5), and all endoscopes were sterilized and approved by the Japanese Ministry of Health and Welfare in 1998. Nian Weidong et al. (1998) reported the evaluation of the disinfection effect of oxidative potential water on digestive tract endoscopes. In the investigation of 30 cases of digestive tract endoscopes before disinfection, 29 cases were found to be positive for bacterial culture, and the bacterial amount was as low as 10cfu/ml. More than 105cfu/ml. The main bacterial species are Bacillus subtilis, Staphylococcus, Streptococcus, fungi and so on. Put the gastroscope into the automatic ultrasonic atomizing endoscope disinfection machine, first rinse it with tap water for 30 seconds, then rinse it with oxidizing potential water for 30 seconds, and then atomize it for 90 seconds. After disinfection, the average killing rate is 97%, and the killing rate range Between 90%-100%. Physiological saline containing the patient's serum was injected into the biopsy hole of the gastroscope. After disinfection by the same method as above, HbsAg and HBVDNA were detected by ELISA, Dig dot blot hybridization and PCR. All were positive before disinfection, and all turned negative after disinfection. Gao Zheping (1999) observed the disinfection effect of oxidative potential water on gastroscopes. 30 gastroscopes were cleaned and disinfected by oxidative potential water for 1 minute. % and 99.54%. Li Sheng (2000) applied oxidation potential water to immerse and disinfect gastroscopes artificially contaminated with Escherichia coli and Staphylococcus aureus. The results showed that the killing rates of immersion for 2 minutes were 99.94% and 99.95%. In addition, Sakurai Yukihiro (1995) reported that the gastroscope was disinfected 1000 times with oxidative potential water, and no damage to the gastroscope was found.