Study on test paper for rapid detection of concentration of o-phthalaldehyde disinfectant

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Abstract: Objective To prepare a rapid test strip for detecting the concentration of ortho-phthalaldehyde (OPA) disinfectant. method adopted on Compared with the color of the test paper, the various factors affecting the color reaction of the test paper are studied. Results Na2 SO3, glycine, The concentration of KH2PO4 and methylene blue were 8, 80, 40 and 0. 04 g /L respectively, and the detection time was 2 min, the effect was the best. The addition of KH2PO4 can greatly Improve the color rate; the test paper dyed blue substrate is more conducive to the identification of color. Conclusion The prepared test paper has a good detection effect on unilateral OPA products. and test paper stability, good reproducibility. The method is simple, fast and feasible.

o-phthalaldehyde(OPA)As a new type of medical high-efficiency disinfectant1>> 〕has many advantages,Such as strong sterilization ability,Use low concentration and short action time, etc.2,3>> 〕.However,OPAStrong volatility will cause its concentration to decrease after repeated use,Sterilization effect becomes weak.To ensure the sterilization effect,should be maintainedOPAconcentration in0.3%Above,And to carry out regular testing.Traditional detection methods such as spectrophotometry4>> 〕and chromatography etc5>> 〕all have certain limitations6>> 〕,For example,Need corresponding instrument and operation skills, etc.,Not suitable for ordinary medical personnel in the use of fast,Simple determination of concentration.The test paper method is a chemical colorimetric method based on the different shades of color of the reaction products.,Compared with the color card can be semi quantitative detection,Can meet the requirements of medical rapid detection.1Materials and Methods1.1MaterialsEL204analytical balance;DF-101Smagnetic stirrer;XMTD-8222Vacuum drying oven;Medium speed qualitative filter paper;Sodium sulfite,Glycine,Potassium dihydrogen phosphate and methylene blue are analytically pure;o-phthalaldehyde(98%);o-phthalaldehyde disinfectant(0.5%~0.6%),The above materials are domestic commercial products.1.2PrincipleUsing glycine andOPAThe products generated after the reaction have different shades of yellow(Aldehydes can react with amino acids or amines to form iminesSchiff base7>> 〕,It usually has a certain color.)to determine its concentration,reaction formula8>> 〕Figure1.In addition,OPACan react with sulfite to produce colorless compounds,AsNa2SO3Reaction,The reaction formula is shown in Figure2shown in.The reaction is fast and the simultaneous presence of glycine andNa2SO3in the mixed solution,OPAFirstNa2SO3Reaction,again·1020·ChineseJournalofDisinfection2017;34(11)glycine reaction.The two according to a certain proportion of the solution and the preparation of test paper.,for detectionOPASolution.WhenOPAWhen the concentration is low,Na2SO3Overdose,OPAdoes not react with glycine,No color change on the test paper;WhenOPAWhen the concentration is high,OPAOverdose,It reacts with glycine,The test strip shows the corresponding color.By the presence or absence of color or color depth can be quickly judgedOPAconcentration.This test adds an appropriate amountKH2PO4,Make the mother liquor a stable buffer system,greatly promoted the association of glycineOPAcolor reaction.1.3Method1.3.1Pretreatment of test paper Take medium-speed qualitative filter paper and soak it in absolute ethanol2hPost-drying,and then cut it1cm × 1cmSpecifications,Spare.1.3.2Preparation of mother liquor by colorimetric card,Among them,Na2SO3,Glycine,KH2PO4and methylene blue concentrations were8,80,40and0.04g/L.Immerse the filter paper in the mother liquor10minAfter removing,Placed on a horizontal glass plate50 ℃Lower1hDrying,Spare.The mass concentration was determined by test paper respectively.0.1%,0.2%,0.3%,0.4%and0.5%ofOPASolution,Color rendering2minWhen,Use the camera to shoot the color of the test paper at this time and make a color comparison card..This test is the color effect on the data contrast test paper.,Introducing the Pantone Color Card.Select the most suitable series of colors according to the color of the reaction product,The color number is607U-613U,Figure3.By comparing the color number corresponding to the color test paper,Select the best ratio of raw materials.2Results2.1Test results of influencing factors2.1.1The effect of the chromogenic agent in this test by glycine with excessofOPAReaction showed different shades of yellow,And then to judgeOPAconcentration,Therefore, the amount of glycine has a certain effect on the detection.Respectively prepared glycine concentration20,60,80,100and160g/Lmother liquor,Preparation of filter paper and testing,In2minCompare the Pantone color card and record the color number.,See Table for table1It is known,When the concentration of glycine60g/LandOPAThe test concentration is0.1%When,Test paper turns yellow,and measurement0.2%ofOPASmall color difference in solution,More difficult to distinguish.When the glycine concentration is higher80g/LWhen,Different concentrations of glycine mother liquor made of test paper in the detection of the sameOPAWhen the solution,same color.SuchOPAThe concentration is0.3%When,The color numbers are608;OPAThe concentration is0.4%When,The color numbers are almost610.This shows that within a certain range,The increase of glycine concentration does not affect the color development effect.Therefore,From the point of view of rapid detection and economy,Glycine concentration was selected80g/L.2.1.2Effect of color development accelerators in order to improve the color development rate of test paper,UseKH2PO4As a color promoter.separatelyKH2PO4The concentration is0,40and100g/Lmother liquor,Preparation of test paper,The detection concentration is0.3%ofOPASolution,Record2minColor results,Figure4shown in.Figure4Mediuma,bandcRespectively correspondingKH2PO4The concentration is0,40and100g/LWhen the color effect.Figure4ashown in,No AddKH2PO4When,due to slow reaction,The filter paper is colorless;and joinKH2PO4After,Figure4bandc,Accelerated reaction rate,Test paper turns yellow,DescriptionKH2PO4To promote the role of figure4Visible,KH2PO4The higher the concentration, the darker the color,The more obvious the role of promotion.But figure4cUneven color patches on the surface of the pilot paper,Indicates that the local reaction is too fast.Therefore,While ensuring faster color development,Make color more uniform,Need to choose the right amount.separately preparedKH2PO4The concentration is0,20,40,60and100g/Lmother liquor,Preparation of filter paper and testing.In2minWhen,Contrast Pantone Color Card,Record each test strip color number,Results are shown in the table2shown table2Visible,KH2PO4The concentration is20g/LWhen,The test concentration is0.3%and0.4%ofOPAThe color number of the solution is607,unable to distinguish;KH2PO4The concentration is60g/LWhen,The test concentration is0.2%and0.3%ofOPAThe solution color number is607and608,Small color difference,Not easy to distinguish.And whenKH2PO4The concentration is40g/LWhen,In0.2%,0.3%and0.4%The corresponding color numbers are607,608and610,large color difference,Easy to distinguish.ThereforeKH2PO4low concentration,Color development too slow;concentration is too high,Uneven color development.Therefore,KH2PO4The concentration is40g/LBest for reaction.2.1.3Na2SO3The impactNa2SO3The role is to consume a certain amountOPA.To get its optimum dosage,separately preparedNa2SO3The concentration is4,6,8,10,12g/Lmother liquor,Test paper was prepared and tested for different concentrationsOPASolution.It can be seen from the test results,Na2SO3When the content is low,lower concentrationOPAYou can change the color of the test paper,Unable to judgeOPAThe actual concentration;And whenNa2SO3concentration reached10g/LWhen,Long color development time,and used to detect higher concentrationsOPAThe test paper does not show contrast,Na2SO3The concentration8g/LCan meet the requirements of the color scale,Can also meet the requirements of rapid detection.2.1.4mother liquorpHThe effect of the mother liquorpHForNa2SO3The existence of the state and the degree of color have a greater the appropriatepHLower,The reaction proceeds faster,And the product is stable7>> 〕.used separatelyKH2PO4andK2HPO4PreparationpHFor2~8buffer solution,Preparation of mother liquor and test paper under the same conditions,The detection concentration is0.3%ofOPASolution,In2minRecord the test results,Figure5shown in.Figure5differentpHColor results of test paper prepared from mother liquorby figure5can be seen,WhenpH7When,Almost white on the test paper(No color change).This is because in a neutral or alkaline environment,The Schiff base formed by the reaction is extremely unstable.,Difficult to exist.WhenpH<4When,darker color,This is due to an overdoseH+the existence,Na2SO3cannot exist stably,OPADirect reaction with glycine.Only whenpHFor4~6When,The color effect of the test paper is better.Therefore,of mother liquorpHshould be controlled in4~ effect of color development time on chemical reactions is a continuous process,With the extension of time,Product increase,Color deepening,Decrease in color scale difference,Is not conducive to the effective judgment of concentration.And it takes too long,Not meet the requirements of rapid detection,Need to choose the appropriate time point as the basis for judging the concentration.Test with test paperOPASolution,Every1minContrast Pantone Color Card,Record color number,Results are shown in the table3shown in.Table3Determination at different timesOPAThe color number of the colorOPA(%/wt)different time(min)The color number123450.1000<607<6070.2<607<6076076086080.36076086096106110.46086106116126120.5609611611612612by table3Visible,to determine0.3%ofOPASolution test paper as an example,With the extension of time,color number607Change611,This indicates an increase in the cumulative product on the test paper.,Color becomes darker.1minWhen,WithOPAIncreased concentration,The color number of the test paper is continuous,The color difference between adjacent color numbers is small.,More difficult to distinguish;2minAfter,Determination0.4%and0.5%ofOPAThe test paper color number of the solution is611or612,No color difference,Unable to determine concentration.Therefore,Combined with the requirement of effective judgment and rapid detection of concentration,Select2minfor the detection time.2.1.6The effect of the stain is judged based on the color of the test paper.OPAConcentration,The darker the color,The higher the concentration.But when the human eye judges,Similar depth of yellow,Difficult to distinguish,Measured value may deviate from true value.Therefore, add a background color to the test paper,More conducive to judging color changes,Reduce the error of actual detection.Two kinds of mother liquor without adding and adding methylene blue were prepared respectively and the test paper was made.,measured separatelyOPASolution,Record2minThe color change effect of the test paper when,The results are shown in the figure6shown in.Figure6Color rendering effect of undyed and methylene blue stained test paperFigure6-aIs the test effect of undyed test paper,Contrast Pantone color card can be seen,The undyed test paper is measured at a concentration0.2%,0.3%and0.4%ofOPAWhen the solution(The minimum effective germicidal concentration of disinfectant is0.3%),The color numbers are respectively607,608and610,Small color difference,That is, the color difference is small.,If a color scale is made,In·1022·ChineseJournalofDisinfection2017;34(11)Difficult to distinguish unknown solutions in actual detectionOPAconcentration.Figure6-bIs the test effect of methylene blue dyeing test paper,Also find the corresponding color number in the Pantone color card.,Respectively2225,2254and2282,Large difference in color number between adjacent detection concentrations,is blueyellow greenThe process of changing the color of green,Easily distinguished by the human eye.Therefore,Add a certain amount of methylene blue to the mother liquor,to dye it blue substrate,Enriched the discoloration range of the test paper,It is beneficial to the effective judgment of concentration in detection.2.2Test strip stability test resultsThe optimum conditions described above are usedOPAPreparation of test paper,And the preparation of the test paper at room temperature sealed preservation3Months.Remove the test paper and use it to detect different concentrationsOPASolution,In2minRecord the color development effect of the test paper when,Figure7shown in.Figure7Save3After months, the color effect of the test paperTest paper preservation3months later,its in2minWhen the color effect and the new test paper(See Figure6b)There is no significant difference,Description under sealed storage conditions,The stability of the test paper is good,ComplianceOPARequirements for testing.In addition,Repeated preparation of test paper under the same conditions,and use it to detectOPASolution,get the same result,No significant difference,It shows that the reproducibility of the test paper is better..3DiscussionPhthalaldehyde disinfectant is mainly used for disinfection and sterilization of endoscopes and other instruments in hospitals.To ensure the sterilization effect,To be tested for effective concentration before use(0.3%Above).In this study, a test paper was prepared to quickly determine the concentration..This method is mainly throughOPAColoration of imine substances generated by reaction with glycine on test paper,According to the color depth to judge the concentration.When preparing the test paper,The base paper needs to be soaked in the mother liquor.In this study, the amount of color reagent and color promoter in the mother liquor,mother liquorpH,The influencing factors such as staining agent and color development time are discussed.,Sensitive for preparation,Reliable test strips provide reference.The results of the study show,When glycine is used as a color developer,its concentration selection80g/Lappropriate;toKH2PO4As a color accelerator can accelerate the color reaction,shorten the color time,its concentration selection40g/Lappropriate;of mother liquorpHIt has an important influence on the stability of the product.,Directly determine the color effect of the test paper,should be controlled in4~6;It is very important to choose the appropriate time point as the basis for reading the concentration.,Time is too short,Then adjacentOPASmall color difference between concentrations,More difficult to distinguish,And the time is too long,It does not meet the requirements of rapid detection.,Therefore, the color development time is set2min;Using methylene blue as a stain,The base of the test paper dyed blue,Can enrich the discoloration range of the test paper,It is beneficial to the effective judgment of concentration in detection,its concentration0.04g/Lappropriate.To verify the stability of the prepared test paper,Keep it sealed at room temperature3months after testingOPASolution.The results showed that there was no significant difference between the new test paper and the new test paper.,Description under sealed storage conditions,The stability of the test paper is good.This study aimedOPAThe problem of rapid detection of disinfectant,prepared a test paper.WhenOPAconcentration below0.3%When,Test paper surface is blue or light blue;WhenOPAconcentration higher0.3%When,The surface of the test paper is yellow-green or green,Can quickly and effectively practical application,for differentOPADisinfectant,The test paper needs to be reacted with its series of standard concentrations to obtain a colorimetric card.,And then applied to the actual detection of the disinfectant.


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