A method for separating and detecting dichlorohydantoin

Abstract

The invention relates to a method for separating and detecting dichlorohydantoin, and belongs to the field of analytical chemistry. The method comprises: using a reducing agent to carry out a reduction reaction with dichlorohydantoin, and then using ion chromatography to detect chloride ions generated by the reaction, using a chromatographic column of an anion exchange column during detection, and the mobile phase is divided into phase A and phase B, phase A is water, and phase B is an alkaline aqueous solution, and the content of dichlorohydantoin is calculated according to the content of chloride ions. The method of the invention has high sensitivity, good specificity, and reliable accuracy.

Description

Technical Field

[0001] The invention relates to the field of analytical chemistry, and in particular to a method for separating and detecting dichlorohydantoin. Background Art

[0002] Dichlorohydantoin, chemical name is 1,3-dichloro-5,5-dimethylhydantoin, and its chemical structure is shown in the following formula:

[0003]

[0004] Dichlorohydantoin is a common impurity in the bromination reagent dibromohydantoin. In the drug synthesis process, when dibromohydantoin is used as a bromination reagent, it will lead to the production of corresponding chlorinated impurities. The activity of chlorinated impurities is lower than that of bromides, which affects subsequent reactions and the control of related substances. Therefore, the content of dichlorohydantoin needs to be controlled, otherwise it will have a significant impact on drug safety.

[0005] At present, the United States Pharmacopoeia (USP), the European Pharmacopoeia (EP), the Japanese Pharmacopoeia (JP) and the Chinese Pharmacopoeia (Ch.P.) do not include the corresponding separation and detection methods, and there is no prior art that discloses its detection method. In order to better and more accurately control the impurities in the product and ensure the quality of the drug, it is necessary to study the analysis method suitable for dichlorohydantoin. Summary of the invention

[0006] The purpose of the present invention is to provide a method for separating and detecting dichlorohydantoin. The method of the present invention can effectively separate and determine the content of dichlorohydantoin, and the method has high sensitivity, good specificity, and reliable accuracy, and can be used for quality control of dichlorohydantoin in medicines.

[0007] A method for separating and detecting dichlorohydantoin comprises: using a reducing agent to carry out a reduction reaction with dichlorohydantoin, and then using ion chromatography to detect chloride ions generated by the reaction, wherein a chromatographic column of an anion exchange column is used for detection, and a mobile phase is divided into an A phase and a B phase, wherein the A phase is water and the B phase is an alkaline aqueous solution, and the content of the dichlorohydantoin is calculated according to the content of the chloride ions.

[0008] The reducing agent is selected from one of sodium nitrite, Na2SO3, Na2S2O3 and sodium ascorbate. In some embodiments, the reducing agent is selected from one of sodium nitrite or Na2SO3.

[0009] In some embodiments, the mass ratio of the dichlorohydantoin to the reducing agent is 1:1.5 to 1:2.5.

[0010] In some embodiments, the reducing agent can be an aqueous solution of the reducing agent. In some embodiments, the reducing agent is an aqueous solution of sodium nitrite or an aqueous solution of Na2SO3.

[0011] The anion exchange column is selected from Dionex AS18 anion exchange column, Dionex AS10 anion exchange column, Dionex AS11 anion exchange column, Dionex AS11-HC anion exchange column, Dionex AS19 anion exchange column, IonPac TM An anion exchange column or a Dionex AS23 anion exchange column. In some embodiments, the anion exchange column is purchased from Thermo Fisher Scientific.

[0012] In some embodiments, the filler of the anion exchange column is styrene-divinylbenzene copolymer (PS-DVB) or ethylvinylbenzene-divinylbenzene copolymer (EVB-DVB).

[0013] The base is selected from one of NaOH, KOH, sodium carbonate or sodium bicarbonate. In some embodiments, the base is selected from NaOH, which is conducive to the separation and detection.

[0014] The aqueous solution of the alkali may contain 2 mmol to 100 mmol of the alkali per 1 L of water.

[0015] In some embodiments, the reduction reaction time may be 1 minute to 12 hours. In some embodiments, the reduction reaction time may be 10 minutes. In some embodiments, the reduction reaction time may be 30 minutes. In some embodiments, the reduction reaction time may be 1 hour.

[0016] In some embodiments, the temperature of the reduction reaction may be 5° C. to 70° C. In some embodiments, the temperature of the reduction reaction may be 20° C. In some embodiments, the temperature of the reduction reaction may be 30° C.

[0017] In some embodiments, the volume ratio of phase A to phase B is 0:100 to 80:20. In some embodiments, the volume ratio of phase A to phase B is 80:20. In some embodiments, the volume ratio of phase A to phase B is 0:100.

[0018] In some embodiments, phase A and phase B are gradient eluted according to the following table:

[0019] Time (min) Phase A (%) Phase B (%) 0.0 80 20 10.0 80 20 10.1 0 100 17.0 0 100 17.1 80 20 25.0 80 20

[0020] In some embodiments, in addition to the chromatographic column of the anion exchange column, a guard column can be further used during detection. In some embodiments, the guard column is selected from one of Dionex AG18, Dionex AG10, Dionex AG11, Dionex AG11-HC, Dionex AG19 or Dionex AG23. In some embodiments, the guard column is a Dionex AG18 guard column.

[0021] In some embodiments, the method for separating and detecting dichlorohydantoin may include the following steps or be implemented according to the following steps:

[0022] 1) Take an appropriate amount of the sample to be tested containing dichlorohydantoin, add a solvent to dissolve it, then add a reducing agent, and mix well;

[0023] 2) Set instrument parameters: detector, chromatographic column, guard column, flow rate of mobile phase, column temperature;

[0024] 3) taking a certain amount of the solution in step 1) and injecting it into an ion chromatograph to complete the separation and determination of dichlorohydantoin.

[0025] The solvent described in step 1) is water or a mixed solution of methanol and water.

[0026] In some embodiments, in step 1), the mass ratio of the sample to be tested to the reducing agent is 1:1.5 to 1:2.5.

[0027] In step 1), each 1 ml of the solvent may contain 0.05 mg to 2.5 mg of the sample to be tested. In some embodiments, in step 1), each 1 ml of the solvent may contain 0.5 mg of the sample to be tested.

[0028] The flow rate of the mobile phase may be 0.8 ml / min to 1.2 ml / min. In some embodiments, in step 2), the flow rate of the mobile phase is 0.8 ml / min. In some embodiments, in step 2), the flow rate of the mobile phase is 1.0 ml / min. In some embodiments, in step 2), the flow rate of the mobile phase is 1.2 ml / min.

[0029] In step 2), the temperature of the chromatographic column box is 25° C. to 35° C. In some embodiments, the temperature of the chromatographic column box is 25° C.; in some embodiments, the temperature of the chromatographic column box is 30° C.; in some embodiments, the temperature of the chromatographic column box is 35° C.

[0030] In step 2), the detector may be a suppressed conductivity detector.

[0031] In step 3), the sample solution injection volume may be 10 μl to 100 μl. In some embodiments, the sample solution injection volume is 10 μl. In some embodiments, the sample solution injection volume is 100 μl.

[0032] In some embodiments, the method for separating and detecting dichlorohydantoin comprises the following steps or can be implemented according to the following steps:

[0033] 1) Take an appropriate amount of the sample to be tested containing dichlorohydantoin, add methanol to dissolve it, then add sodium nitrite aqueous solution or Na2SO3 aqueous solution, and mix well;

[0034] 2) The flow rate of the mobile phase was set to 0.8 ml / min to 1.2 ml / min, the detector was a suppressed conductivity detector, the chromatographic column was a Dionex AS18 anion exchange column, the guard column was a Dionex AG18 guard column, the flow rate of the mobile phase was set to 0.8 ml / min to 1.2 ml / min, and the column box temperature was set to 25° C. to 35° C.;

[0035] 3) Take 10 μl to 100 μl of the sample solution in step 1) and inject it into an ion chromatograph to complete the separation and determination of dichlorohydantoin.

[0036] The ion chromatograph may be a Dionex ICS-5000+ system and a Chameleon 6.8 workstation or other suitable and feasible systems.

[0037] In some embodiments, a method for separating and detecting dichlorohydantoin comprises: using a reducing agent to carry out a reduction reaction with dichlorohydantoin, and then detecting the chloride ions generated by the reaction by ion chromatography, wherein a Dionex AS18 anion exchange column is used for detection, and the mobile phase is divided into phase A and phase B, phase A is water, and phase B is an aqueous solution of alkali, and the content of dichlorohydantoin is calculated according to the content of chloride ions; the reducing agent is one of sodium nitrite, Na2SO3, Na2S2O3 and sodium ascorbate; and the alkali is one of NaOH, KOH, sodium carbonate or sodium bicarbonate.

[0038] In some embodiments, a method for separating and detecting dichlorohydantoin comprises: using a reducing agent to carry out a reduction reaction with dichlorohydantoin, and then detecting the chloride ions generated by the reaction by ion chromatography, wherein a Dionex AS18 anion exchange column is used for detection, and the mobile phase is divided into phase A and phase B, phase A is water, and phase B is an aqueous solution of alkali, and the content of dichlorohydantoin is calculated according to the content of chloride ions; the reducing agent is one of sodium nitrite and Na2SO3; and the alkali is one of NaOH, KOH, sodium carbonate or sodium bicarbonate.

[0039] In some embodiments, a method for separating and detecting dichlorohydantoin comprises: using a reducing agent to carry out a reduction reaction with dichlorohydantoin, and then detecting the chloride ions generated by the reaction by ion chromatography, wherein a Dionex AS18 anion exchange column is used for detection, and the mobile phase is divided into phase A and phase B, phase A is water, and phase B is an aqueous solution of NaOH, and the content of dichlorohydantoin is calculated based on the content of chloride ions; the reducing agent is one of sodium nitrite and Na2SO3.

[0040] In some embodiments, a method for separating and detecting dichlorohydantoin comprises: using a reducing agent to carry out a reduction reaction with dichlorohydantoin, and then detecting the chloride ions generated by the reaction by ion chromatography, wherein a Dionex AS18 anion exchange column is used for detection, and the mobile phase is divided into phase A and phase B, phase A is water, and phase B is an aqueous solution of NaOH, and the content of dichlorohydantoin is calculated based on the content of chloride ions; the reducing agent is one of sodium nitrite or Na2SO3; in the mobile phase, the volume ratio of phase A to phase B is 0:100 to 80:20.

[0041] In some embodiments, a method for separating and detecting dichlorohydantoin comprises: using a reducing agent to carry out a reduction reaction with dichlorohydantoin, and then detecting the chloride ions generated by the reaction by ion chromatography, using a Dionex AS18 anion exchange column for detection, and the mobile phase is divided into phase A and phase B, phase A is water, and phase B is an aqueous solution of NaOH, and the content of dichlorohydantoin is calculated according to the content of chloride ions; the reducing agent is one of sodium nitrite or Na2SO3; in the mobile phase, phase A and phase B are gradient eluted according to the following table:

[0042] Time (min) Phase A (%) Phase B (%) 0.0 80 20 10.0 80 20 10.1 0 100 17.0 0 100 17.1 80 20 25.0 80 20

[0043] By adopting the separation method of the present invention, the time for separating and detecting dichlorohydantoin can be within 25 minutes.

[0044] In the above or below, regardless of whether the words "about" or "approximately" are used, all the numbers disclosed herein are approximate values. The value of each number may differ by 1%, 2%, 5%, 7%, 8% or 10%.

[0045] The method provided by the present invention can effectively separate dichlorohydantoin impurities in drugs, with a separation degree of 1.5 or more, 2.5 or more, or 5 or more, and complete baseline separation, which can solve the problem that dichlorohydantoin slowly releases chloride ions in aqueous solution, resulting in incomplete hydrolysis and low detection results. The method of the present invention is simple, fast, accurate and highly sensitive. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Ion chromatogram overlay of the reference solution in Example 1;

[0047] Figure 2 Ion chromatogram overlay of each solution in Example 1;

[0048] Figure 3 Ion chromatogram overlay of each solution in Example 2;

[0049] Figure 4 Ion chromatogram overlay of each solution when the amount of reducing agent added in Example 3 is 1.5 times that of the test sample;

[0050] Figure 5 Ion chromatogram overlay of each solution when the amount of reducing agent added in Example 3 is 2.5 times that of the test sample;

[0051] Figure 6 Ion chromatogram of the reference solution-NaNO2 in Example 4;

[0052] Figure 7 Ion chromatogram of the reference solution -Na2SO3 in Example 4;

[0053] Figure 8 Ion chromatogram of the reference solution - Na2S2O3 in Example 4;

[0054] Fig. 9 Ion chromatogram of the reference solution - sodium ascorbate in Example 4;

[0055] Fig.10 Ion chromatogram of the reference solution in Example 5;

[0056] Fig.11 Ion chromatogram of the reference solution in Example 6;

[0057] Fig.12 Ion chromatogram of the reference solution in Example 7;

[0058] Fig.13 Ion chromatogram of the reference solution in Example 8;

[0059] Fig.14 Ion chromatogram of the reference solution in Example 9. DETAILED DESCRIPTION

[0060] The embodiment of the present invention discloses a method for separating and detecting dichlorohydantoin. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method of the present invention has been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0061] In the embodiment of the present invention,

[0062] The content of residual dichlorohydantoin in the test sample was calculated according to the following formula:

[0063]

[0064] Where: A T is the peak area of ​​the impurity to be detected in the test solution;

[0065] A S The average value of the peak area of ​​the impurity to be tested by three consecutive injections of the reference solution;

[0066] W T is the sample weight of the test solution, mg;

[0067] W S The mass of the impurity to be tested weighed to prepare the reference solution, mg;

[0068] D T is the dilution factor of the test solution;

[0069] D S is the dilution multiple of the reference solution;

[0070] P is the content of the reference substance, %.

[0071] The recovery rate is calculated as follows:

[0072]

[0073] Determination of added amount (μg) = W T+S ×(C T+S -C T )×1000,

[0074] Theoretical addition amount (μg) = C S ×V,

[0075]

[0076] Where: W T+S is the sample amount of the spiked solution of the test sample, mg;

[0077] C T+S is the impurity residue measured in the spiked solution of the test sample, ppm;

[0078] C T is the residual amount of impurities measured in the test solution, ppm;

[0079] C S is the concentration of impurities in the reference stock solution added to the test sample spike solution, μg / ml;

[0080] V is the volume of the reference stock solution added to the test sample spike solution, ml;

[0081] W S is the weight of the corresponding impurity in the reference stock solution, mg;

[0082] D S is the dilution multiple of the reference solution;

[0083] P is the content of the reference substance, %.

[0084] In the present invention, 50 mM NaOH aqueous solution: pipette 2625 μL of 50% NaOH solution into 1L ultrapure water and shake well;

[0085] In the present invention, the density of 50% NaOH solution is 1.525 g / ml, c=1000ρω / M=1000×1.525×50% / 40=19.06 mol / L.

[0086] In the present invention, Dionex AS18 anion exchange column was purchased from Thermo Fisher Scientific.

[0087] In order to further understand the present invention, the present invention is described in detail below in conjunction with embodiments.

[0088] Instrument: Ion chromatograph Dionex ICS-5000+ system and workstation; automatic injection.

[0089] Example 1

[0090] Instruments and conditions

[0091] Chromatographic column: Dionex AS18 anion exchange column, 4.0*250mm; Dionex AG18 guard column, 4.0*50mm;

[0092] Detector: Suppressed conductivity detector;

[0093] Flow rate: 1.0 mL / min;

[0094] Column temperature: 30°C;

[0095] Injection volume: 100 μL;

[0096] Mobile phase A: ultrapure water;

[0097] Mobile phase B: 50 mM NaOH aqueous solution (V:V:);

[0098] Elution gradient:

[0099] Time (min) Eluent A(%) Eluent B (%) 0.0 80 20 10.0 80 20 10.1 0 100 17.0 0 100 17.1 80 20 25.0 80 20

[0100] Running time: 25min;

[0101] Experimental procedures

[0102] NaNO2 solution: Weigh about 250 mg of NaNO2 into a 25 ml volumetric flask, dissolve it in ultrapure water and make up to volume.

[0103] Reference substance stock solution: accurately weigh 25 mg of dichlorohydantoin into a 100 ml volumetric flask, dissolve and make up to volume with ultrapure water, and shake well;

[0104] Reference solution: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 5 ml of NaNO2 solution, make up to volume with ultrapure water, and shake well.

[0105] Test solution: Take about 50 mg of dibromohydantoin, accurately weigh it, put it in a 100 ml volumetric flask, add 2 ml of methanol to dissolve it, add 5 ml of NaNO2 solution, make up to volume with ultrapure water, and shake well.

[0106] Test sample spike solution: take about 50 mg of the test sample, accurately weigh it, put it in a 100 ml volumetric flask, add 2 ml of methanol to dissolve it, add 5 ml of reference stock solution, add 5 ml of NaNO2 solution, make up to volume with ultrapure water, and shake well;

[0107] Take the reference solution, test solution and test sample spiked solution, perform ion chromatography analysis under the above conditions and record the chromatogram.

[0108] Result analysis: Figure 1 The chromatographic peak with a retention time of about 7.2 minutes is the superimposed chromatographic peak of chloride ions. The peak area of ​​the reference solution was stable and the sensitivity was high when it was continuously injected. Figure 2 The recovery rate of 100% test sample spiked was unqualified.

[0109] Depend on Figure 1 and Figure 2 It can be seen that when the ratio of dibromohydantoin concentration to sodium nitrite concentration in the solution is 1:1, the method is not suitable for the determination of dichlorohydantoin.

[0110] Example 2

[0111] Instruments and conditions

[0112] Same as Example 1

[0113] Experimental procedures

[0114] NaNO2 solution: Weigh about 1000 mg of NaNO2 into a 50 ml volumetric flask, dissolve it in ultrapure water and make up to volume.

[0115] Blank solution: Pipette 2 ml of methanol and 5 ml of NaNO2 solution into a 100 ml volumetric flask and make up to volume with ultrapure water.

[0116] Reference substance stock solution: accurately weigh about 25 mg of dichlorohydantoin into a 100 ml volumetric flask, dissolve and dilute to volume with ultrapure water, and shake well; transfer 5 ml of the above solution into a 50 ml volumetric flask and dilute to volume with ultrapure water;

[0117] Reference solution: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 5 ml of NaNO2 solution, and make up to volume with ultrapure water.

[0118] Test sample solution: Take about 50 mg of the test sample, accurately weigh it, place it in a 100 ml volumetric flask, add 2 ml of methanol to dissolve it, then add 5 ml of NaNO2 solution and make up to volume with ultrapure water.

[0119] Test sample spike solution: Take about 50 mg of the test sample, weigh accurately, place in a 100 ml volumetric flask, add 2 ml of methanol to dissolve, add 5 ml of reference sample stock solution, add 5 ml of NaNO2 solution, and make up to volume with ultrapure water;

[0120] Take blank solution, reference solution, detection limit solution, test solution and test spiked solution, perform ion chromatography analysis under the above conditions and record the chromatogram.

[0121] Result analysis: Figure 3 The chromatographic peak with a retention time of about 7.9 minutes is the chromatographic peak of chloride ions.

[0122] Depend on Figure 3 It can be seen that under this detection method, the chloride ion specificity is good, and the recovery rate of the test sample is 94.6%.

[0123] The quantitative limit of dichlorohydantoin in this detection method can reach 4ng / ml, and the detection limit is 1ng / ml. This method can be used to determine the content of trace dichlorohydantoin.

[0124] Example 3

[0125] Instruments and conditions

[0126] Same as Example 1

[0127] Experimental procedures

[0128] NaNO2 solution: Weigh about 1000 mg of NaNO2 into a 50 ml volumetric flask, dissolve it in ultrapure water and make up to volume.

[0129] Reference substance stock solution: accurately weigh about 25 mg of dichlorohydantoin into a 100 ml volumetric flask, dissolve and dilute to volume with ultrapure water, and shake well; transfer 5 ml of the above solution into a 50 ml volumetric flask and dilute to volume with ultrapure water;

[0130] Reference solution-1.5: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 3.75 ml of NaNO2 solution, and make up to volume with ultrapure water.

[0131] Reference solution-2.5: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 6.25 ml of NaNO2 solution, and make up to volume with ultrapure water.

[0132] Test sample solution-1.5: Take about 50 mg of the test sample, accurately weigh it, place it in a 100 ml volumetric flask, add 2 ml of methanol to dissolve it, then add 3.75 ml of NaNO2 solution and make up to volume with ultrapure water.

[0133] Test sample solution-1.5: Take about 50 mg of the test sample, accurately weigh it, put it in a 100 ml volumetric flask, add 2 ml of methanol to dissolve it, then add 6.25 ml of NaNO2 solution and make up to volume with ultrapure water.

[0134] Test sample spike solution-1.5: Take about 50 mg of the test sample, accurately weigh it, put it in a 100 ml volumetric flask, add 2 ml of methanol to dissolve it, add 3.75 ml of the reference substance stock solution, add 5 ml of NaNO2 solution, and make up to volume with ultrapure water;

[0135] Test sample spike solution-2.5: Take about 50 mg of the test sample, accurately weigh it, put it in a 100 ml volumetric flask, add 2 ml of methanol to dissolve it, add 5 ml of reference sample stock solution, add 6.25 ml of NaNO2 solution, and make up to volume with ultrapure water

[0136] Take each reference solution, test solution and test spiked solution, perform ion chromatography analysis under the above conditions, and record the chromatogram.

[0137] Result analysis: Figure 4-Figure 5 The chromatographic peak with a retention time of about 7.0 minutes is the chromatographic peak of chloride ions.

[0138] Figure 4 The recovery rate of dichlorohydantoin spiked was 107.8%. Figure 5 The recovery rate of dichlorohydantoin was 115.2%. Figure 4 , Figure 5 It can be seen that when the concentration of sodium nitrite added is 1.5 to 2.5 times the concentration of dibromohydantoin, the spiked recovery rate of dichlorohydantoin in dibromohydantoin is good, and it can be used for the detection of dichlorohydantoin.

[0139] Example 4

[0140] Instruments and conditions

[0141] Same as Example 1

[0142] Experimental procedures

[0143] NaNO2 solution: Weigh about 1000 mg of NaNO2 into a 50 ml volumetric flask, dissolve it in ultrapure water and make up to volume.

[0144] Reference substance stock solution: accurately weigh about 25 mg of dichlorohydantoin into a 100 ml volumetric flask, dissolve and dilute to volume with ultrapure water, and shake well; transfer 5 ml of the above solution into a 50 ml volumetric flask and dilute to volume with ultrapure water;

[0145] Reference solution - NaNO2: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 5 ml of NaNO2 solution, and make up to volume with ultrapure water.

[0146] Reference solution - Na2SO3: Weigh about 100 mg of Na2SO3 into a 100 ml volumetric flask, dissolve it in ultrapure water, add 5 ml of reference stock solution, and 2 ml of methanol, and make up to volume with ultrapure water.

[0147] Reference solution - Na2S2O3: Weigh about 160 mg of sodium thiosulfate pentahydrate into a 100 ml volumetric flask, dissolve it in ultrapure water, add 5 ml of reference stock solution, and 2 ml of methanol, and make up to volume with ultrapure water.

[0148] Reference solution - VC Na: Weigh about 100 mg of sodium ascorbate into a 100 ml volumetric flask, dissolve it in ultrapure water, add 5 ml of reference stock solution, and 2 ml of methanol, and make up to volume with ultrapure water.

[0149] Take each reference solution, perform ion chromatography analysis under the above conditions, and record the chromatogram.

[0150] Result analysis: Figure 6 to Figure 9 The chromatographic peak with a retention time of about 7.0 minutes is the chromatographic peak of chloride ions.

[0151] Depend on Figure 6 to Figure 9 It can be seen that sodium nitrite and sodium sulfite can be used as reducing agents when measuring dichlorohydantoin.

[0152] Example 5

[0153] Instruments and conditions

[0154] Instrument: Ion chromatograph (Dionex ICS-5000 + );

[0155] Chromatographic column: Dionex AS18 anion exchange column, 4.0*250mm; Dionex AG18 guard column, 4.0*50mm;

[0156] Detector: Suppressed conductivity detector;

[0157] Flow rate: 1.0ml / min;

[0158] Column temperature: 30°C;

[0159] Injection volume: 10 μl;

[0160] Eluent A: ultrapure water;

[0161] Eluent B: 50 mM NaOH aqueous solution;

[0162] Elution gradient:

[0163] Time (min) Eluent A(%) Eluent B (%) 0.0 80 20 10.0 80 20 10.1 0 100 17.0 0 100 17.1 80 20 25.0 80 20

[0164] Running time: 25min;

[0165] Experimental procedures

[0166] NaNO2 solution: Weigh about 1000 mg of NaNO2 into a 50 ml volumetric flask, dissolve it in ultrapure water and make up to volume.

[0167] Reference substance stock solution: accurately weigh about 25 mg of dichlorohydantoin into a 100 ml volumetric flask, dissolve and dilute to volume with ultrapure water, and shake well; transfer 5 ml of the above solution into a 50 ml volumetric flask and dilute to volume with ultrapure water;

[0168] Reference solution: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 5 ml of NaNO2 solution, and make up to volume with ultrapure water.

[0169] Take the reference solution, perform ion chromatography analysis under the above conditions, and record the chromatogram.

[0170] Result analysis: Fig.10 The chromatographic peak with a retention time of about 7.0 minutes is the chromatographic peak of chloride ions. Fig.10 It can be seen that this method can be used to determine the content of trace dichlorohydantoin.

[0171] Example 6

[0172] Instruments and conditions

[0173] Instrument: Ion chromatograph (Dionex ICS-5000 + );

[0174] Chromatographic column: Dionex AS18 anion exchange column, 4.0*250mm; Dionex AG18 guard column, 4.0*50mm;

[0175] Detector: Suppressed conductivity detector;

[0176] Flow rate: 0.8ml / min;

[0177] Column temperature: 30°C;

[0178] Injection volume: 100 μl;

[0179] Eluent A: ultrapure water;

[0180] Eluent B: 50 mM NaOH aqueous solution;

[0181] Elution gradient:

[0182] Time (min) Eluent A(%) Eluent B (%) 0.0 80 20 10.0 80 20 10.1 0 100 17.0 0 100 17.1 80 20 25.0 80 20

[0183] Running time: 25min;

[0184] Experimental procedures

[0185] NaNO2 solution: Weigh about 1000 mg of NaNO2 into a 50 ml volumetric flask, dissolve it in ultrapure water and make up to volume.

[0186] Reference substance stock solution: accurately weigh about 25 mg of dichlorohydantoin into a 100 ml volumetric flask, dissolve and dilute to volume with ultrapure water, and shake well; transfer 5 ml of the above solution into a 50 ml volumetric flask and dilute to volume with ultrapure water;

[0187] Reference solution: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 5 ml of NaNO2 solution, and make up to volume with ultrapure water.

[0188] Take the reference solution, perform ion chromatography analysis by three consecutive injections under the above conditions, and record the chromatogram.

[0189] Result analysis: Fig.11 The chromatographic peak with a retention time of about 8.8 minutes is the chromatographic peak of chloride ion. This method can be used to determine the content of trace dichlorohydantoin.

[0190] Example 7

[0191] Instruments and conditions

[0192] Instrument: Ion chromatograph (Dionex ICS-5000 + );

[0193] Chromatographic column: Dionex AS18 anion exchange column, 4.0*250mm; Dionex AG18 guard column, 4.0*50mm;

[0194] Detector: Suppressed conductivity detector;

[0195] Flow rate: 1.2 ml / min;

[0196] Column temperature: 30°C;

[0197] Injection volume: 100 μl;

[0198] Eluent A: ultrapure water;

[0199] Eluent B: 50 mM NaOH aqueous solution;

[0200] Elution gradient:

[0201] Time (min) Eluent A(%) Eluent B (%) 0.0 80 20 10.0 80 20 10.1 0 100 17.0 0 100 17.1 80 20 25.0 80 20

[0202] Running time: 25min;

[0203] Experimental procedures

[0204] NaNO2 solution: Weigh about 1000 mg of NaNO2 into a 50 ml volumetric flask, dissolve it in ultrapure water and make up to volume.

[0205] Reference substance stock solution: accurately weigh about 25 mg of dichlorohydantoin into a 100 ml volumetric flask, dissolve and dilute to volume with ultrapure water, and shake well; transfer 5 ml of the above solution into a 50 ml volumetric flask and dilute to volume with ultrapure water;

[0206] Reference solution: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 5 ml of NaNO2 solution, and make up to volume with ultrapure water.

[0207] Take the reference solution, perform ion chromatography analysis by three consecutive injections under the above conditions, and record the chromatogram.

[0208] Result analysis: Fig.12 The chromatographic peak with a retention time of about 5.9 minutes is the chromatographic peak of chloride ion. This method can be used to determine the content of trace dichlorohydantoin.

[0209] Example 8

[0210] Instruments and conditions

[0211] Chromatographic conditions:

[0212] Instrument: Ion chromatograph (Dionex ICS-5000+);

[0213] Chromatographic column: Dionex AS18 anion exchange column, 4.0*250mm; Dionex AG18 guard column, 4.0*50mm;

[0214] Detector: Suppressed conductivity detector;

[0215] Flow rate: 1.0ml / min;

[0216] Column temperature: 25°C;

[0217] Injection volume: 100 μl;

[0218] Eluent A: ultrapure water;

[0219] Eluent B: 50 mM NaOH aqueous solution;

[0220] Elution gradient:

[0221] Time (min) Eluent A(%) Eluent B (%) 0.0 80 20 10.0 80 20 10.1 0 100 17.0 0 100 17.1 80 20 25.0 80 20

[0222] Running time: 25min;

[0223] Experimental procedures

[0224] NaNO2 solution: Weigh about 1000 mg of NaNO2 into a 50 ml volumetric flask, dissolve it in ultrapure water and make up to volume.

[0225] Reference substance stock solution: accurately weigh about 25 mg of dichlorohydantoin into a 100 ml volumetric flask, dissolve and dilute to volume with ultrapure water, and shake well; transfer 5 ml of the above solution into a 50 ml volumetric flask and dilute to volume with ultrapure water;

[0226] Reference solution: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 5 ml of NaNO2 solution, and make up to volume with ultrapure water.

[0227] Take the reference solution, perform ion chromatography analysis by three consecutive injections under the above conditions, and record the chromatogram.

[0228] Result analysis: Fig.13 The chromatographic peak with a retention time of about 6.9 minutes is the chromatographic peak of chloride ion. This method can be used to determine the content of trace dichlorohydantoin.

[0229] Example 9

[0230] Instruments and conditions

[0231] Chromatographic conditions:

[0232] Instrument: Ion chromatograph (Dionex ICS-5000 + );

[0233] Chromatographic column: Dionex AS18 anion exchange column, 4.0*250mm; Dionex AG18 guard column, 4.0*50mm;

[0234] Detector: Suppressed conductivity detector;

[0235] Flow rate: 1.0ml / min;

[0236] Column temperature: 35°C;

[0237] Injection volume: 100 μl;

[0238] Eluent A: ultrapure water;

[0239] Eluent B: 50 mM NaOH aqueous solution;

[0240] Elution gradient:

[0241] Time (min) Eluent A(%) Eluent B (%) 0.0 80 20 10.0 80 20 10.1 0 100 17.0 0 100 17.1 80 20 25.0 80 20

[0242] Running time: 25min;

[0243] Experimental procedures

[0244] NaNO2 solution: Weigh about 1000 mg of NaNO2 into a 50 ml volumetric flask, dissolve it in ultrapure water and make up to volume.

[0245] Reference substance stock solution: accurately weigh about 25 mg of dichlorohydantoin into a 100 ml volumetric flask, dissolve and dilute to volume with ultrapure water, and shake well; transfer 5 ml of the above solution into a 50 ml volumetric flask and dilute to volume with ultrapure water;

[0246] Reference solution: Pipette 5 ml of reference stock solution into a 100 ml volumetric flask, add 2 ml of methanol and 5 ml of NaNO2 solution, and make up to volume with ultrapure water.

[0247] Take the reference solution, perform ion chromatography analysis by three consecutive injections under the above conditions, and record the chromatogram.

[0248] Result analysis: Fig.14 The chromatographic peak with a retention time of about 7.1 minutes is the chromatographic peak of chloride ion. This method can be used to determine the content of trace dichlorohydantoin.

Claims

1. A method for separating and detecting dichlorohydantoin, characterized in that: include: A reducing agent is used to carry out a reduction reaction with dichlorohydantoin, and then the chloride ions generated by the reaction are detected by ion chromatography. During the detection, a chromatographic column of an anion exchange column is used, and the mobile phase is divided into phase A and phase B, phase A is water, and phase B is an aqueous solution of alkali, and the content of dichlorohydantoin is calculated according to the content of chloride ions; the reducing agent is selected from one of sodium nitrite, Na2SO3, Na2S2O3 and sodium ascorbate; the feed mass ratio of dichlorohydantoin to the reducing agent is 1:1.5~1:2.5; the volume ratio of phase A to phase B is 0:100 to 80:20; the chromatographic column is selected from one of Dionex AS18 anion exchange column, Dionex AS10 anion exchange column, Dionex AS11 anion exchange column, Dionex AS11-HC anion exchange column, Dionex AS19 anion exchange column, IonPacTM anion exchange column and Dionex AS23 anion exchange column; and / or a protective column can be further used, and the protective column is selected from Dionex One of Dionex AG18, Dionex AG10, Dionex AG11, Dionex AG11-HC, Dionex AG19 and Dionex AG23 guard columns; or the filler of the anion exchange column is styrene-divinylbenzene copolymer or ethylvinylbenzene-divinylbenzene copolymer; the base is selected from one of NaOH, KOH, sodium carbonate and sodium bicarbonate; and / or each 1L of water can contain 2mmol~100mmol of the base.

2. The method according to claim 1, wherein the reduction reaction time is 1 minute to 12 hours; and / or the reaction temperature is 5°C to 70°C.

3. The method according to any one of claims 1-2, characterized in that: The method comprises the following steps: 1) Take an appropriate amount of the sample containing dichlorohydantoin, add a solvent to dissolve it, then add a reducing agent and mix well; 2) Set the instrument parameters: detector, chromatographic column, guard column, flow rate of mobile phase, column temperature; 3) Take a certain amount of the solution in step 1) and inject it into an ion chromatograph to complete the separation and determination of dichlorohydantoin.

4. The method according to claim 3, wherein the solvent is water or a mixed solution of methanol and water; and / or each 1 ml of the solvent contains 0.05 mg to 2.5 mg of the sample to be tested.

5. The method according to claim 3, wherein: The flow rate of the mobile phase is 0.8 ml / min to 1.2 ml / min; the detector is a suppressed conductivity detector; and the column box temperature of the chromatographic column is 25°C to 35°C.

Images