阅读说明：本技术 空气净化器病毒去除率的检测方法 (Method for detecting virus removal rate of air purifier ) 是由 单慧媚 彭三曦 赵超然 罗林波 王少培 于 2019-09-05 设计创作，主要内容包括：本发明公开了一种空气净化器病毒去除率的检测方法,包括以下步骤：将乙烯基封口膜封住的病毒培养基、微生物采样器放置在空气净化器的试验舱内,消毒,使试验舱达到背景浓度；采用雾化器向试验舱内注入Phi-X174接种液,待Phi-X174接种液在试验舱内均匀分布；等待40min,运用微生物采样器取样,运行空气净化器,每间隔10min运用微生物采样器取样1次,共取样2次,将取样的病毒在有氧条件下进行培养,检测,计算病毒去除率。本发明具有检测空气净化器去除浮游病毒的性能的有益效果。(The invention discloses a method for detecting the virus removal rate of air purifiers, which comprises the following steps of placing a virus culture medium sealed by a vinyl sealing film and a microorganism sampler in a test chamber of the air purifier, sterilizing the test chamber to enable the test chamber to reach background concentration, injecting Phi-X174 inoculation liquid into the test chamber by using an atomizer, waiting for the Phi-X174 inoculation liquid to be uniformly distributed in the test chamber, waiting for 40min, sampling by using the microorganism sampler, operating the air purifier, sampling 1 time by using the microorganism sampler every 10min, sampling 2 times in total, culturing the sampled viruses under aerobic conditions, detecting, and calculating the virus removal rate.)

1. The detection method for the virus removal rate of the air purifier is characterized by comprising the following steps:

step , placing the virus culture medium and the microorganism sampler sealed by the vinyl sealing film in a test chamber of the air purifier, and sterilizing to ensure that the test chamber reaches the background concentration;

injecting Phi-X174 inoculation liquid into the test chamber by using an atomizer, and uniformly distributing the Phi-X174 inoculation liquid in the test chamber;

and step three, waiting for 40min, sampling by using a microorganism sampler, operating the air purifier, sampling 1 time by using the microorganism sampler every 10min, sampling 2 times in total, culturing the sampled viruses under an aerobic condition, detecting and calculating the virus removal rate.

2. The method for detecting the virus removal rate of an air purifier as claimed in claim 1, wherein the virus in the step is escherichia coli.

3. The method for detecting the virus removal rate of an air purifier of claim 2, wherein the virus culture medium in the step is prepared by a double-layer plate method and is placed with side of the virus culture medium facing upwards.

4. The method for detecting the virus removal rate of the air purifier as claimed in claim 1, wherein the concentration of the Phi-X174 inoculation liquid in the second step is 5X 10⁹PFU/mL。

5. The method for detecting the virus removal rate of the air purifier as claimed in claim 1, wherein the Phi-X174 inoculation liquid in the second step is uniformly distributed by rotating a stirring fan for 10 min.

6. The method for detecting the virus removal rate of an air purifier according to claim 1, wherein the culture temperature in the third step is 35 ± 1 ℃ and the culture time is 18 ± 2 hours.

Technical Field

The invention relates to the field of air purification, in particular to a method for detecting the virus removal rate of air purifiers.

Background

9/15/2015, GB/T18801-2015 air purifier, and the national standard is officially published. The new standard was officially implemented in 2016, 3 months and 1 day. The new standard defines that the basic technical indexes (core parameters) of the air purifier are 'clean air quantity' (CADR value for short) and 'accumulated purification quantity' (CCM value for short), namely 'purification capacity' and 'continuity of the purification capacity' of the air purifier product; dividing the noise limit value of the air purifier into 4 grades from low to high; the energy efficiency level value of the air purifier aiming at different pollutant purifying capacities is improved, and the air purifier is divided into a qualified grade and a high-efficiency grade.

It is worth noting that the standard of "air purifier" in China emphasizes the purification level, and specific detection methods and parameter constraints are lacked for specific items (such as viruses and the like). Serious health effects brought by MERS virus (korea middle east respiratory syndrome incident) and SARS virus (chinese influenza virus incident) have caused human panic to viruses in the air, and thus, the requirement for an air purifier cannot be limited to conventional bacteria removal, and effective inactivation of indoor air viruses can really reduce health risks.

Disclosure of Invention

objects of the present invention are to address at least the above problems and to provide at least the advantages that will be described later.

The invention also aims to provide methods for detecting the virus removal rate of air purifiers, which have the effect of detecting indoor viruses removed by the air purifiers so as to judge the intensity of virus removal performance of the air purifiers.

To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided an air purifier virus removal rate detection method, comprising the steps of:

step , placing the virus culture medium and the microorganism sampler sealed by the vinyl sealing film in a test chamber of the air purifier, and sterilizing to ensure that the test chamber reaches the background concentration;

injecting Phi-X174 inoculation liquid into the test chamber by using an atomizer, and uniformly distributing the Phi-X174 inoculation liquid in the test chamber;

and step three, waiting for 40min, sampling by using a microorganism sampler, operating the air purifier, sampling 1 time by using the microorganism sampler every 10min, sampling 2 times in total, culturing the sampled viruses under an aerobic condition, detecting and calculating the virus removal rate.

Preferably, the virus described in step is E.coli.

Preferably, the virus culture medium described in step is prepared using a double plate method, and is placed with sides of the virus-containing medium facing upward.

Preferably, the concentration of the Phi-X174 inoculation liquid in the step two is 5X 10⁹PFU/mL。

Preferably, the Phi-X174 inoculum is uniformly distributed in the second step, and a stirring fan is adopted to rotate for 10 min.

Preferably, the culture temperature in step three is 35 +/-1 ℃ and the culture time is 18 +/-2 h.

The invention at least has the following beneficial effects that the detection method for removing the virus removal rate of air purifiers can detect the floating virus removal performance of the air purifiers, provides a detection standard and a detection method for screening better air purifiers, enables the air purifiers to effectively inactivate indoor air viruses, and provides better living environment for people.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a schematic flow chart of the detection method of the present invention;

FIG. 2 is a graph showing the natural viral attenuation rates in tester A and tester B of the present invention;

FIG. 3 shows the distribution characteristics of the planktonic virus of the present invention (Phi-X174);

FIG. 4 shows the results of the natural attenuation test of the virus according to the present invention;

FIG. 5 is a graph showing the natural decay rate of the virus of the present invention within 40 to 60min after virus injection.

Detailed Description

The present invention is further described in detail below with reference to the figures and examples to enable those skilled in the art to practice the invention with reference to the description.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.

The present embodiment provides a method for detecting a virus removal rate of air purifiers, as shown in fig. 1, including the following steps:

step , placing a virus culture medium and a microorganism sampler sealed by a vinyl sealing film in a test chamber of the air purifier, wherein the microorganism sampler is a solid impact type sampler, the test chamber is set according to GB/T21551.3-2010 and GB/T18801, and the volume of the test chamber of the air purifier is set to be 30m³Sterilizing the test chamber to reach background concentration determined when test virus is to be injected, wherein the temperature and the relative humidity inside the test chamber are 23 +/-2 ℃ and the humidity is 50 +/-5 percent respectively;

preparation of virus culture medium: viral media should be prepared immediately prior to the experiment to provide nutrients for Phi-X174 growth. Mixing 5mL of Escherichia coli (E.coli C) culture solution with 5mL of upper agar, transferring into a 15mL test tube, ensuring no air bubbles, pouring into 5mL of lower agar, mixing, solidifying, and inverting to obtain virus culture medium;

preparation of escherichia coli (e.coli C) culture solution:

a) adding 10-25 mL LTSB into a 250mL sterilized triangular flask, inoculating E.coli C with an inoculating loop, and culturing at 35 +/-1 ℃ and 225 +/-25 r/min for 12 h;

b) inoculating the E.coli C culture solution into 100mL of TSB culture medium according to the ratio of 1:100 for dilution, then transferring into a 1L triangular flask, and culturing at 35 + -1 ℃ and 225 + -25 r/min for 12h to obtain the Escherichia coli culture solution.

Injecting the 2mLPhi-X174 inoculation liquid into the test chamber by using an atomizer, operating a stirring fan for 10min, and uniformly distributing the Phi-X174 inoculation liquid in the test chamber;

preparation of Phi-X174 inoculum:

a) inoculating the cultured E.coli C culture solution into 5-10 mL of Phi-X174 with 1.0X (109-1010) PFU/mL, and stirring for 1-5 h at 35 +/-1 ℃ until the E.coli C is dissolved, wherein the absorbance stops reducing, indicating that the dissolution is finished;

b) centrifuging at 3000rpm for 20min, removing E.coli C thallus, sucking supernatant into sterile test tube, filtering the supernatant with 0.22um filter, and diluting the filtrate to make its concentration (5 + -2) X1010 PFU/mL to obtain Phi-X174 culture solution;

c) the Phi-X174 culture medium was diluted 10-fold with saline solution to a concentration of 5X 109PFU/mL to give a Phi-X174 inoculum.

Measuring the natural attenuation rate for times within 90min after the stirring fan stops rotating in the step two, wherein the optimal initial concentration is 100-250 PFU, and the result of repeated test shows that the virus concentration is most stable in 40-60 min;

therefore, after the stirring is stopped for 40min, the microorganism sampler is used for impact sampling of the virus culture medium, and the two impactors are operated for times respectively, wherein the sampling amount can be adjusted according to the concentration of the injected virus, at least 100L is needed, and less than 50L of sampling amount is not recorded because of the volume error of the sample air due to the ineffective volume;

simultaneously operating the air purifier under the following operating conditions: the equipment runs for 20min, the rated air flow runs, the sampling point with the height of 120cm and the distance of the impactor is 100 cm;

after the air purifier operates for 20min, namely after the stirring fan stops stirring for 60min, sampling by using a microorganism sampler at intervals of 10min, respectively adding virus culture media into the two impactors, and operating the two impactors for times respectively;

the virus sampled from the impactor was cultured aerobically, plaque numbers were determined, and corrected using the colony count conversion chartThen, 1m is counted³PFU value of (1).

The calculation process is as follows:

a) calculating a natural attenuation rate Bi according to the following formula according to the average value of the initial concentration and the final concentration, wherein the natural attenuation rate Bi is expressed in percentage;

in the formula, Bi: natural attenuation rate (%); ci: Phi-X174 distribution stabilizes the mean value of the initial concentration after i hours; ct: average of the final concentrations of Phi-X174 after i +20 min.

b) Correction of the initial concentration (PFU/m)³)：

The corrected value Sc for the starting concentration is calculated according to the following formula:

in the formula, Sc: correction of the initial concentration (PFU/m)³) (ii) a Bi: natural attenuation rate (%); pt: mean value of the starting concentration of Phi-X174 (PFU/m) before operation of the apparatus³)。

c) Removal rate (%) of floating virus:

calculating the removal rate R of floating viruses according to the following formula, subtracting the average value of the final concentration from the corrected average value (Sc) of the initial concentration, and dividing by the corrected value of the initial concentration;

in the formula, R: removal rate (%) of floating virus; and (C) Sc: corrected initial concentration mean (PFU/m)³) (ii) a Cf: average value of final concentration of virus (PFU/m) after 20min of operation of air purifier device³)。

d) Tightness of test chamber

Regarding the tightness of the test chamber, it should be satisfied that, when the distribution of Phi-X174 is stable, the naturally decreasing concentration value is at least 80% of the initial concentration value after 20 min;

in the formula: v: tightness (%) of the test chamber; li: mean value of the initial concentration of Phi-X174 (PFU/m) after 1 hour of stabilization of the distribution of Phi-X174³) (ii) a And Lt: average value of the final concentration of Phi-X174 after i +20min (PFU/m)³)。

< test verification data and analysis >

a) Comparative testing of planktonic virus sampling methods

And collecting the floating viruses by adopting three microorganism sampling methods, and carrying out comparative analysis on the results so as to verify the effectiveness of the standard adopting a solid impact method. The solid-impacting method, the liquid-impacting method and the filtering method are all started at the same time after 50min of spraying the virus (Phix 174). Sampling under the same conditions found that the number of plaques produced by the solid impact method was the highest, 166PFU, as shown in Table 1. The liquid impact and filtration methods exhibited a smaller number of plaques, 14PFU and 58PFU, respectively, than the solid impact method. The above results show that: the number of viruses depends on the method of sampling. The number of plaques in each medium was greatest by solid impact, followed by liquid impact and filtration. The results of the solid impact method were 0.5min at 100L/min for 50L of sample, 10min at 12.5L/min for 125L of sample, and 10min at 4L/min for 40L of sample. The units are set as the average plaque number (PFU/medium) of the medium, taking into account the differences in the sampling volume and sampling time for the three methods.

TABLE 1 solid-percussion, liquid-percussion and filtration method for virus collection and number of plaques in culture medium after incubation

b) Natural attenuation Rate Effect and Performance analysis of different testers

And performing a comparison test of the tester A and the tester B so as to verify the effectiveness of the detection method in the standard. Samples were taken twice at 40min and 60min after Phi-X174 virus spraying, and each tester was replicated four times.

The results of the natural attenuation rate of the virus in air are shown in table 2, and it is understood from table 2 that: the average natural attenuation rate of tester a was 9.50%, which was 13.07% lower than the average natural attenuation rate of tester B. The standard deviation of the natural decay rates of testers a and B were 6.27% and 4.49%, respectively. The standard deviation of tester a was slightly higher, as shown in fig. 2, where N in fig. 2 represents the natural attenuation rate (%), a represents the average number of plaque, B represents the natural attenuation rate (%) of tester a, and c represents the natural attenuation rate (%) of tester B. The natural decay rates of the testers A and B within 2min are both lower than 20%.

To statistically confirm the difference in the natural decay rates of the two testers, a t-test was performed assuming the same variance. The results of the two-sided test at the 0.05 significance level showed a t statistic of 2.179. This is less than the critical value of 2.447. Thus, the comparative tests for tester a and B were not significantly different.

TABLE 2 results of virus sampling tests by different testers

c) Distribution characteristics of planktonic viruses

In order to confirm the distribution concentration of the floating virus in the test chamber in the standard, comparison tests of different sampling points are carried out, namely, the virus concentrations at 2 different positions in the test chamber are compared and analyzed.

2 different sites of decontamination completion were selected (defined as trials 1 and 2), with trial 1 being located on the left striker of the test chamber and trial 2 being located on the right. The sampling medium in the impactor is positioned on a table inside the cabin, so that a tester does not need to enter the cabin in the test.

Injecting virus (Phi-X174) for 10min, operating the stirring fan, and stopping the stirring fan after the virus is uniformly distributed. After waiting for 40min, 100L of sample was taken and measured 4 times at 2 sites with 10min intervals by the impact method.

In test 1, the mean and standard deviation were 18800PFum, respectively³And 5302PFU/m³(ii) a In test 2, the mean and standard deviation were 16325PFU/m, respectively³And 5189PFU/m³The difference between the mean values was 13.16% and the standard deviation was 2.13%. the results showed that the difference in the concentrations of the virus was not large between the left and right sides, and it was confirmed that the virus in the test chamber was uniformly distributed in step , and the results are shown in FIG. 3, in which P represents the Plaque Forming Unit (PFU) per cubic meter (m)³) A represents the total average number of plaques, b represents the number of plaques to the left of the test chamber, and c represents the number of plaques to the right of the test chamber.

d) Decay characteristics of planktonic viruses over time (applicability of Natural and Total decay measurement time)

In the present standard test method, the natural attenuation concentration and the measurement time of the attenuation concentration are 20min, i.e. within 40-60min after virus injection. This condition followed a test of determination of the natural decrease at intervals of 10min within 60min after injection of the virus. FIG. 4 shows that the reduction in viral concentration is reduced after 40min of injection and the viral concentration is stable, where P in FIG. 4 represents Plaque Forming Units (PFU) per cubic meter (m)³) Time after injection of t virus, in min.

To confirm the validity of the measurement time, the determination of the natural decay rate was repeated 6 times. After the virus was injected into the test chamber, samples were taken at 40min, 50min and 60min using the ballistic method.

The test results showed that the natural attenuation rate was 8.0% between 40min and 50min, 8.1% between 50min and 60min, and 15.6% between 40min and 60min, as shown in FIG. 5, R in FIG. 5 is the natural attenuation rate (%), a is the natural attenuation rate (%) between 40-60min, b is the natural attenuation rate (%) between 40-50min, and c is the natural attenuation rate (%) between 50-60 min. The natural decay rate was less than 20% in all cases, demonstrating good test chamber sealing. Therefore, the measurement time in the present standard is feasible.

The standard deviations at 40min and 50min were 4.6%, at 50min and 60min 3.3%, and at 40min and 60min a minimum of 2.5%. This means that the measurement times specified in this standard method (40-60min, 20min long) are valid.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the specification and examples, which are fully applicable to various fields of endeavor for which the invention may be embodied and broadly contemplated, and further modifications may be readily made thereto by those skilled in the art, and it is therefore not intended to be limited to the details shown and described herein without departing from the general concept as defined by the appended claims and their equivalents.