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Determination of Sugars in Tobacco by Ion Chromatography   Water-soluble sugars mainly refer to glucose, fructose and sucrose, which are common sugars in tobacco. And they play a very important role in both the quality of tobacco and tobacco products, as well as the flavor and taste of cigarettes.   In this paper, an ion chromatography is used to determine the content of water-soluble sugar. Experimenters use IC6300 ion chromatography with an ampere detector. eluent: NaOH and sodium acetate. simple pre-treatment, with good recovery and high sensitivity, this method is suitable for the determination of water-soluble sugars.   Keywords: tobacco products; sugars; ion chromatography   1. Experiment Section   1.1 Instruments and Reagents   Wayeal IC6300 Series Ion Chromatography   Ion chromatography: Wayeal IC6300 series ion chromatography with ampere detector (Au working electrode) Auto sampler: AS2800 Sugar column: 250mm*4.0mm D-(+) Glucose, anhydrous (99%); Fructose (99%); E-(+) Sucrose, AR; Benzoic acid (99%); Disposable syringe (2mL) Water system syringe filter One ten-thousandth electronic balance Water is prepared by the ultrapure water purifier of Wayeal with a conductivity of 18.2 MΩ - cm (25 ℃).   1.2 Instrument Parameter Sugar column: 250mm*4.0mm Temperature: 30℃ Detector temperature: 35 ℃ Eluent: 250mM NaOH in A; 50mM NaOH in B; 1M sodium acetate in C; pure water in D; gradient eluting; Flow rate: 0.3mL/min Ampere detection pulse mode: Au electrode, sugars, quaternary potential Injection volume: 25uL   1.3 Sample Pretreatment Flue-cured tobacco: 0.1g sample (accurate to 0.1mg) in a 250mL conical flask, add 200mL 0.1% benzoic acid solution, put the lid on and place in an ultrasonic cell for 30min, then the solution is detected on a machine after passing through a 0.22μm filter membrane. Cigar: 0.1g sample (accurate to 0.1mg) into a 250mL conical flask, add 50mL 0.1% benzoic acid solution, put the lid on and place in an ultrasonic cell for 30min, then the solution is detected on a machine after passing through a 0.22μm filter membrane.   2. Results and Discussion   2.1 Chromatogram A series of standard working curves of 0.1mg/L, 0.5mg/L, 1.0mg/L, 2.0mg/L, 5.0mg/L, 10.0mg/L, and 20.0mg/L are pipetted respectively. Then the multipoint overlap standard curve spectra obtained according to 1.2 working conditions as shown in Figure 1. The linear correlation coefficients of glucose, sucrose and fructose under this condition are above 0.999 with good linearity.   Figure 1 Overlapping Chromatogram of Glucose, Sucrose and Fructose   Figure 2 Standard Curve of Glucose   Figure 3 Standard Curve of Sucrose   Figure 4 Standard Curve of Fructose   No Compound Linear Equation (math.) Correlation Coefficient 1 Glucose y=3044.02000x+431.15880 0.99941 2 Sucrose y=896.97000x+88.82726 0.99933 3 Fructose y=1723.92600x+174.80090 0.99941   2.2 Sample Result Cigar and flue-cured tobacco samples are detected under the working conditions of 1.2. The sample chromatogram are shown as Figures 5 and 6. The target glucose, sucrose and fructose peaks in the sample chromatogram are symmetrical with good separation and non-interfering peaks.   Figure 5 Chromatogram of Cigar   Fig. 6 Chromatogram of Flue-cured Tobacco   Table 2. Sample Results Samples compound Sample Test Content/%   Flue-cured Tobacco -1 Glucose 1.87 Sucrose 0.45 Fructose 1.73   Flue-cured Tobacco - 2 Glucose 1.93 Sucrose 0.44 Fructose 1.65   Cigar-1 Glucose 0.024 Sucrose N.D. Fructose 0.03   Cigar-2 Glucose 0.025 Sucrose N.D. Fructose 0.03     3.Conclusion   An ion chromatography method for the determination of sugar in tobacco products is established by using Wayeal 6300 series ion chromatography with an ampere detector. The samples were pre-treated and then separated by an ion chromatography column and quantified by external standard method, which is capable of qualitative and quantitative analysis of water-soluble sugars in the samples. The method is simple and easy to operate, with good repeatability, sensitivity and accuracy, which can be used for the determination of sugar content in tobacco products.

Troubleshooting of High Performance Liquid Chromatography (HPLC)   There are many test instruments used in the laboratory, and high-performance liquid chromatography (HPLC) is one of them. The instrument is based on classical chromatography, citing the theory of gas chromatography, and technically it changes the traditional mobile phase to high-pressure delivery. This article will give you the brief introduction of the chromatography, characteristics, failure causes, and treatment methods of high-performance liquid chromatography (HPLC).     Introduction of High-performance Liquid Chromatography   High performance liquid chromatograph (HPLC) is an instrument based on the principle of high performance liquid chromatography, which is mainly used to analyze less-volatile and thermal-unstable organic compounds with high boiling point and large molecular weight. It consists of solvent bottles, pump, sample injector, chromatographic column, detector, recorder and workstation.     How does high performance liquid chromatography work?   The mobile phase in the reservoir is pumped into the system by a high-pressure pump, and the sample solution passes through a sample injector then enters the mobile phase, which loads the sample solution into a chromatographic column (stationary phase). Because the various components in the sample solution have different distribution coefficients in the two phases, when they are moving relatively in the two phases, after repeated adsorption-desorption distribution processes, the moving speed of each component is greatly different, and the components are separated into single components flowing out of the column in turn. When passing through the detector, the sample concentration is converted into electrical signal and transmitted to the recorder, and the data is printed out in the form of chromatogram.     Applications of High-Performance Liquid Chromatography   HPLC is widely used in food, pharmaceutical, environment, agriculture and scientific research   1. Application in environmental analysis: It can be used for the analysis of cyclic aromatic hydrocarbons (PAHs), pesticide residues, etc.   2. Application in food analysis: It can be used for food nutrition analysis, food additive analysis, food contaminant analysis, etc.   3. Application in life science: Purification, separation, and determination of molecular weight substances in life science, genetic engineering, clinical chemistry, molecular biology, and biochemistry can be studied at the molecular level.   4. Application in the medical examination: analysis and determination of metabolites in body fluids, pharmacokinetics, clinical drug monitoring, etc.   5. Application in inorganic analysis: analysis of anions and cations, etc.     Common Faults and Treatment Methods of High-Performance Liquid Chromatography   Fault Description Cause Analysis Solution   Front panel status indicator does not light up Cable connection failure Open the chassis and reconnect reliably Switching power supply module cannot work and supply power Replace the switching power module Signal intensity too low Bubbles are generated in the flow cell Flush the flow cell and degasify the mobile phase   Prompt deuterium lamp failure Deuterium lamp cannot be lit Restart the instrument. If the fault cannot be eliminated, please replace the deuterium lamp.     Common troubleshooting of autosampler   Fault Description Cause Analysis Solution Abnormal electrical initialization of the instrument­­­ Software prompts: The zero-point optocoupler of the horizontal motor fails. 1.  Restart the instrument 2.  Check the sample chamber for any obstacles 3.  Check the sensor at the corresponding position for any obvious abnormal phenomena such as looseness and line breakage 4.  Call the after-sale service to solve the problem Software prompts: The zero-point optocoupler of the vertical motor fails. Software prompts: The zero-point optocoupler of the tray motor fails. Software prompts: The zero-point optocoupler of the syringe motor fails. Software prompts: EEPROM is unable to read or write. 1.  Restart the instrument 2.  Call the after-sale service to solve the problem The software for the injection process indicated an exception Software prompts: Sample vial is missing 1.  Check whether the sample vial position is consistent with the software setting position 2.  Restart the instrument 3.  Call the after-sale service to solve the problem Software prompts: The door is open 1.  Check whether the door is normally closed 2.  Check the door sensor for abnormalities 3.  Restart the instrument 4.  Call the after-sale service to solve the problem Line fault The status light on the front panel is not on 1.  Restart the instrument 2.  Check whether the power cord is reliably connected 3.  Check whether the power switch is on 4.  Check the fuse for damage 5.  Call the after-sale service to solve the problem The autosampler does not trigger the chromatogram 1.  Check whether the trigger line is reliably connected 2.  Check whether the instrument serial line is connected reliably 3.  Check whether the software instrument networking light is flashing Fluid line fault There are obvious bubbles in the syringe during injection 1.  Perform flushing fluid line process 2.  Check whether the pipe joints are loose 3.  Check joints for leakage 4.  Too little liquid in the sample vial There are small bubbles in the fluid line during injection Poor reproducibility of sample injection 1.  No ultrasonic processing to the sample 2.  No ultrasonic processing to the wash solvent 3.  There are obvious air bubbles in the pipeline syringe during injection 4.  The sample vial was reused without cleaning   Common troubleshooting of pump   Fault Description Cause Analysis Solution If the front panel status indicator is not light, the connection may be loose, Open the shell, and reconnect reliably. Detection of power supply module Replacement power supply module Pump pressure is 0 pump head with air Open purge valve, with syringe pumping, until there is liquid from the empty valve flow, and then tighten the valve. Pressure alarm pressure limit range setting unreasonable According to the actual test needs, set a reasonable pressure limit range. Pipeline blockage leads to excessive pressure. Check whether the pipeline is gambling after pump head. Leakage causes too little pressure Check whether there is any damage to all levels of pipelines and streets after the pump head. The buzzer keeps buzzing at a frequency of 0.5HZ. Motor blocked, pressure upper limit alarm, pressure lower limit alarm, liquid leakage alarm. Check and determine the cause of the error, and then solve it according to the situation The buzzer beeps 3 times at a frequency of 1HZ and then stops Leak sensor failure, pressure sensor failure, fan failure, photoelectric switch failure, solvent threshold alarm, unsuccessful initialization. Check and determine the cause of the error, and then solve it according to the situation                        

Determination of Cadmium in Food by Atomic Absorption Graphite Furnace Method   This paper establishes an analytical method for the determination of cadmium in food by atomic absorption graphite furnace method with reference to the standard “GB 5009.15-2023 National Standard for Food Safety Determination of Cadmium in Food”.   Keywords: Atomic absorption, autosampler, food, cadmium   1. Experiment Method   1.1 Instrument Configuration Atomic Absorption Spectrophotometer AA2300 Series   Table 1 Configuration List of Atomic Absorption Spectrophotometer No Modular Qty 1 Atomic Absorption Spectrophotometer AA2310 1 2 Graphite Furnace 1 3 Autosampler 1 4 Cooling Water Circulator 1 5 High Purity Argon 1 6 Graphite Tube 1   1.2 Reagents and Experiment Material 1.2.1 Nitric acid solution (1+99):Pipette 10mL of nitric acid and slowly add to 990mL of water and mix well. 1.2.2 Cd Standard Solutions: 100mg/L 1.2.3 One in ten thousand analytical balances 1.2.4 Centrifuge   1.3 Sample Pretreatment Take 0.05g sample or more (between 0.05~0.0.08), and add 10mL of 3% dilute nitric acid to the sample. Shake for 5min and centrifuge at 8000r/min for 12min. Take the supernatant and test on the machine.   2. Result and Discussion   2.1 Spectral Conditions of Cadmium   Heating Method Graphite Furnace Method Testing Method Peak Height Injection Volume 20μL Spectral Bandwidth 0.4nm Characteristic Wavelength 228.8nm Ignite Method AA-BG Lamp Current 3mA   2.2 Standard Curve Testing and Sample Chromatogram   Gradient Concentration Table of Standard Curve(ng/mL) Curve Point 1 2 3 4 Cadmium standard solution 0.40 1.20 1.60 2.00   2.3 Linearity of Standard Curve   3. Conclusion   From the experimental results, the linear correlation coefficient of cadmium in the concentration range of 0.40-2.00ng/mL is greater than 0.999. The method is accurate, reliable and sensitive, and can be used for the determination of cadmium in food.                                

Determination of Sugar Alcohol in Food by High Performance Liquid Chromatography     1. Method and Principle   Determined by high performance liquid chromatography with an RID detector and quantified by external standard method.   2. Instrument Configuration and Experimental Methods   2.1 Instrument Configuration No. System Configurations Qty 1 P3210B Binary High Pressure Gradient Pump 1 2 CT3210 Colum Oven 1 3 AS3210 Autosampler 1 4 RI Detector 1 5 4.6*250mm 5μm Amino Column 1 6 SmartLab Workstation 1   Table1 Configuration List 2.2 Experimental Method 2.2.1 Preparation of Reagents and Standards No. Reagents Purity 1 Acetonitrile Chromatographically pure 2 4 kinds of sweeteners mix standards 40g/L Table 2 List of Reagents and Standards   Standard curve: The mixed standard (40 mg/mL) of the four sweeteners was diluted with water to a concentration of 1.6 mg/mL, 2.4 mg/mL, 3.2 mg/mL, 4.0 mg/mL, 4.8 mg/mL , 6.0 mg/mL series of concentration working curves.   2.22 Chromatography Conditions Chromatography Column Amino column， 4.6*250mm, 5μm Mobile Phase Acetonitrile ：Water=80：20 Flow Rate 1mL/min Temperature 30°C Cell Temperature 40°C Injection Volume 20μL Table 3 Chromatography Conditions 2.2.3 Sample Pretreatment Samples of non-protein beverages should not be less than 200 mL and placed in an airtight container after being fully mixed. 10g of sample into a 50 mL volumetric flask, and fix the volume to 50 mL with water, shake well and detected on a machine after passing through a 0.22μm filter membrane.   3. Experimental Results   3.1 System Suitability   Figure 1 Chromatogram of 6.0mg/mLsweetener mixing standard   Notes: As the figure shows, there are good shape peaks of erythritol, xylitol, sorbitol and maltitol, and no other peaks around the target peaks, which meet the experimental requirements.   3.2 Linearity Figure 2 Standard Curve of Erythritol   Figure 3 Standard Curve of Xylitol   Figure 4 Standard Curve of Sorbitol                                         Figure 5 Standard Curve of Maltose   The concentrations of mixing standard curves of the four sweeteners are 1.6 mg/mL, 2.4 mg/mL, 3.2 mg/mL, 4.0 mg/mL, 4.8 mg/mL, and 6.0 mg/mL. As the figure shows, the linear correlation coefficients of the standard curves of four sweeteners are above 0.999, which satisfied the experimental requirements.   3.3 Repeatability   Figure 6 Repeatability Chromatogram of 6 Injections of 3.2mg/mL Sweetener Mixing Standard         Retention Time No. Erythritol Xylitol Sorbitol Maltitol 1 8.407 11.365 15.637 36.644 2 8.414 11.374 15.638 36.658 3 8.415 11.377 15.644 36.645 4 8.412 11.374 15.638 36.635 5 8.426 11.391 15.670 36.696 6 8.436 11.405 15.680 36.701 RSD(%) 0.128 0.128 0.120 0.077 Table 4 6 Injections of Retention Time Repeatability         Peak Area No. Erythritol Xylitol Sorbitol Maltitol 1 228.976 239.243 234.601 224.837 2 230.029 238.083 239.130 224.900 3 224.656 237.784 236.914 222.373 4 227.415 239.595 238.192 222.414 5 227.455 240.591 238.963 223.679 6 228.492 239.876 237.412 227.865 RSD(%) 0.809 0.450 0.705 0.913 Table 5 6 Injections of Peak Area Repeatability   Note: As the table shows, the retention time RSD of erythritol, xylitol, sorbitol and maltitol are 0.128%, 0.128%, 0.120%, 0.077%, and the repeatability of retention time was less than 0.2%, which satisfied the experimental requirements. The peak area RSDs of erythritol, xylitol, sorbitol and maltitol are 0.809%, 0.450%, 0.705% and 0.913%. The repeatability of peak area was less than 1%, which satisfied the experimental requirements.   3.4 Detection Limit   Figure 7 Chromatogram of 1.6mg/mL Sweetener Mixing Standard   Note: As the Figure 7 shows, the concentration of 1.6 mg/mL sweetener mixing standard, the triple SNR is calculated from the detection limits of erythritol, xylitol, sorbitol, and maltitol are 0.01 mg/mL, 0.012 mg/mL, 0.015 mg/mL, and 0.03 mg/mL, which meet the experimental requirements.   3.5 A branded Non-protein Beverage   Figure 8 Chromatogram of a Branded Beverage in 2 Injections   Samples Peak Area Sample-1 209.594 Sample-2 209.001 Arithmetic Mean Value 209.298 Table 6 2 Injections for a Branded Beverage   As the chromatogram shows, erythritol is detected in a branded beverage and xylitol, sorbitol and maltitol are not detected. The test results are consistent with the ingredient list. The data in the table are the results of two tests with an absolute difference of 0.14% of the arithmetic mean, which is less than 10% of the standard requirement.   3.6 Attentions   Since the differential refractive index detector is sensitive to the density of the solution, it is recommended that the mobile phase be premixed when doing the experiment.   4 Conclusion   The analytical method introduced in this article refers to the national standard GB 5009.279-2016 (Determination of xylitol, sorbitol, maltitol and erythritol in food), by using a Wayeal LC3200 series high performance liquid chromatograph with a RID detector. The experimental results showed that the system adaptive testing of erythritol, xylitol, sorbitol and maltitol, the peaks are good and there are no other peaks around the target peaks. The RSDs for retention time are 0.128%, 0.128%, 0.120%, and 0.077%, all less than 0.2%. The RSDs of peak area are 0.809%, 0.450%, 0.705%, 0.913% and less than 1%. SNR=3 as detection limit, then detection limits of erythritol, xylitol, sorbitol, and maltitol are 0.01 mg/mL, 0.012 mg/mL, 0.015 mg/mL, and 0.03 mg/mL. The absolute difference between the two measurements is 0.14% of the arithmetic mean, which is less than 10% of the standard requirement. All the above data shows that the results satisfy the experimental requirements.              

Determination of Tyrosol in Wine by High Performance Liquid Chromatography   1. Instrument Configuration and Experiment Methods   1.1 Instrument Configuration   Table 1 Configuration List of Liquid Chromatography No Module Qty 1 P3210B Binary Pump System 1 2 CT3400 Column Oven 1 3 AS3210 Autosampler 1 4 UV 3210 UV Detector 1 5 C18 Column, 4.6*250mm 5μm 1 6 SmartLab Workstation 1   1.2 Experiment Method   1.2.1 Reagent Preparation No Reagents Purity 1 Methanol Chromatographic Grade 2 Tyrosol Standard 98%   1.2.1.1 Tyrosol standard stock solution (1000mg/L): Take the appropriate amount of tyrosol standard, dissolve and Fix the volume with methanol, a standard stock solution with a concentration of 1000mg/L will be prepared, sealed and stocked at -4℃.   1.2.1.2 Tyrosol standard working solution: Pipette the appropriate amount of tyrosol standard stock solution accurately, dilute with methanol to form a series of working curves with concentrations of 0.1mg/L, 1mg/L, 1.5mg/L, 3mg/L, 5mg/L, 7.5mg/L, 10mg/L respectively.   1.2.2 Chromatography Conditions   Table 3 Chromatography Conditions Chromatography Column C18 Column 4.6*150mm, 5μm Mobile Phase A: Methanol, B: Water Flow Rate 1mL/min Column Temperature 40°C Wavelength 222nm Injection Volume 10μL   Table 4 Proportion of Mobile Phase Time/min A B 0 30 70 9 35 65 9.1 100 0 12 100 0 13 30 70 20 30 70   1.2.3 Sample Pretreatment   Take appropriate amount of white wine samples, through the 0.45μm microporous filter membrane, then to be measured.   2. Experimental Result   2.1 System Suitability Fig 1 Chromatogram of 10mg/L Standard   Table 5 10mg/L Standard Test Data Compounds Retention Time Peak Height Peak Area Theoretical Plate Number Tyrosol 7.209 29.398 367.785 7558     Note: From the chromatogram and data, it can be seen that the tyrosol peak shape is good, there are no other peaks around the target peak, and the theoretical plate number is high, which meets the experimental requirements.   2.2 Standard Curve                                        Fig 2 Test Result of Standard Curve   Note: From the above chromatogram, it can be seen that the correlation coefficient value R of tyrosol curve is above 0.999, which meets the experimental requirements.   2.3 Repeatability   Fig 3 Repeatability Chromatogram of 3.75mg/L Standard for 6 Injections   Table 6 Repeatability Test Data of 6 injections for 7.5mg/L Standard         Tyrosol No. Retention Time Peak Area 1 7.205 284.108 2 7.209 286.256 3 7.210 285.346 4 7.216 285.676 5 7.212 286.806 6 7.207 288.199 RSD (%) 0.053 0.485   Note: According to the above table data, it can be seen that the RSD of tyrosol retention time repeatability is 0.053% and the RSD of peak area repeatability is 0.485%, both of which has good repeatability. It meets the experimental requirements.   2.4 Detection Limit Fig 4 Test Chromatogram of 0.1mg/L Standard                                         Table 7 Test Data of 0.1mg/L Standard Compound Retention Time Peak Area SNR Tyrosol 7.210 4.852 41.562   Note: According to the above table data, the detection limit of tyrosol is 0.0073mg/L with 3 times signal-to-noise ratio, which meets the experimental requirements.   2.5 Test Results of a Brand of White Wine Fig 5 Test Chromatogram of a Brand White Wine   Table 8 Test Data of a Brand White Wine Compound Retention Time Peak Area Sample Volume Tyrosol 7.210 4.852 0.275mg/L   Note: 0.275 mg/L of tyrosol was detected in a brand of white wine.   2.6 Spiked Testing Result of a Brand White Wine Fig 6 Spiked Testing Chromatogram of a Brand White Wine   Table 9 Spiked Test Data of a Brand White Wine Compounds Retention Time Peak Area Sample Volume Tyrosol 7.234 71.425 1.799mg/L   Note: Add 15μL of 100mg/L standard in a 1mL white wine, and according to the detection concentration of white wine and the spiked concentration, the theoretical concentration is 1.775 mg/L. From the detection concentration in the above table, the spiked recovery is 101.4%, which meets the experimental requirements.   2.7 Attentions The Tyrosol Standard stock solution needs to be stored at low temperature, otherwise its content will decrease.     3. Conclusion This article introduces the determination of tyrosol content in white wine by Wayeal high performance liquid chromatograph LC3210 series equipped with ultraviolet detector. The experimental results showed that the peak shape of tyrosol is good in the system adaptability test, and there are no other peaks around the target peak, and the theoretical plate number is high, which met the experimental requirements. The curve correlation coefficient R value is above 0.999. The RSD of tyrosol retention time is 0.053%, and the RSD of peak area is 0.485%, which is good reproducibility. The detection limit of tyrosol is 0.0073mg/L. The recoveries are 101.4% with the spiked 1.5mg/L in the sample. The results of the above data meet the requirements of the instrument for the test method.                        

Determination the Content of Acyclovir by High Performance Liquid Chromatography   The analytical method introduced in this article, with reference to the 2020 edition of the Pharmacopoeia of the People's Republic of China in Acyclovir test method, by using Wayeal high performance liquid chromatograph LC3200 series with a DAD detector.   1. Instrument Configuration and Experiment Method   1.1 Instrument Configuration No Name Qty 1 P3210Q Quaternary Pump 1 2 CT3400 Column Oven 1 3 AS3210 Autosampler 1 4 DAD3260 DAD Detector 1 5 Nova Atom PC18 4.6x250mm 5μm 1 6 Chromatography Workstation 1   1.2 Experiment Method   1.2.1 Reagents Preparation   Table 2 List of Reagents No Reagents Purity 1 2 3 4 5 Methanol Phosphoric acid Sodium hydroxide Acyclovir Guanine Chromatographic Purity(LC) GR MOS 98% 99%   1.2.1.1 Test solution: Take 40mg of sample into a 200mL measuring flask, add 2mL of 0.4% sodium hydroxide to dissolve it, then add 25mL of 0.1% (V/V) phosphoric acid solution and dilute it with water to the scale, shake well.   1.2.1.2 Reference solution: Take 1mL of the test solution into a 100mL measuring flask, add 5mL of 0.1% phosphoric acid solution, dilute with water to scale and shake well.   1.2.1.3 Guanine control storage solution: Take 10mg of guanine reference into a 50mL measuring flask, add 5mL of 0.4% sodium hydroxide solution to dissolve it, then add 5mL of 0.1% phosphoric acid solution, dilute it with water to the scale, shake well.   1.2.1.4 Guanine reference solution: Take 1mL of guanine reference storage solution into a 100mL flask, dilute with water and shake well.   1.2.1.5 System suitability solution: Take appropriate amount of each of the reference solution and guanine reference solution, mix in equal volume and shake well.   1.2.2 Chromatography Condition   Table 3 Chromatography Conditions Chromatography Column Nova Atom PC18 Chromatography Column, 4.6*250mm, 5μm Mobile Phase Mobile Phase A: Water Mobile Phase B: Methanol Flow Rate 1mL/min Column Temperature 35°C Wavelength 254nm Injection Volume 20μL   Table 4 Mobile Phase Ratio Time (min) Mobile Phase A Mobile Phase B 0 94 6 15 94 6 40 65 35 41 94 6 51 94 6   2. Experiment Result   2.1 System Suitability Solution Fig 1 Test Chromatogram of System Suitability Solution   Table 5 Test Data System Suitability Solution No Compound Retention Time Peak Area Theoretical plate number Separation 1 Guanine 5.698 138.675 17173 12.334 2 Acyclovir 8.425 139.902 15786 n.a.   Note: From the above graph and the data in the table, it can be seen that Acyclovir and Guanine have better peak shapes and high theoretical plate number. The degree of separation is more than 3.0, which meets the requirements in pharmacopoeia.   2.2 Repeatability Fig 2 Repeatability Chromatogram of 6 Injections of System Suitability   Table 6 Repeatability Data of 6 Injections of System Suitability Solution Retention Time Sample No Guanine Acyclovir       Retention Time 1 5.698 8.408 2 5.701 8.415 3 5.705 8.411 4 5.701 8.405 5 5.705 8.401 6 5.705 8.398 RSD (%) 0.048 0.074     Table 7 Repeatability Data of 6 Injections of System Suitability Solution Peak Area Sample No Guanine Acyclovir       Peak Area 1 136.997 138.836 2 138.496 139.117 3 137.783 139.505 4 136.663 138.204 5 137.755 137.968 6 137.789 139.374 RSD (%) 0.475 0.452   Note: According to the data in the above table, the RSD of retention time of guanine and acyclovir in the system suitability solution is 0.048% and 0.074%, and the RSD of peak area is 0.475% and 0.452%, respectively. The reproducibility results are good and meet the experimental requirements.

Application of Ion Chromatography in Environmental Analysis   Application of Ion Chromtography in Environmental Water Quality   With the development of social economy, water pollution has become an increasingly serious problem. In order to protect the environment and prevent water pollution, it is necessary to monitor rivers, lakes, seas and groundwater. For the treatment, recycling, comprehensive use and discharge of industrial and domestic wastewater, water quality analysis is required first. In the process of analysis, ion chromatography can be applied. The ion chromatography is widely used in water quality analysis because of its high efficiency, stability and accuracy.       Water Quality——Inorganic Anion Analysis

Guo Chengzhan, Secretary of Party Committee and Chairman of China Environmental Protection Industry Association Visited Wayeal for Research and Guidance     On July 27th, Guo Chengzhan, Secretary of Party Committee and Chairman of China Environmental Protection Industry Association (CEPIA), and his delegation visited Wayeal for a research and discussion to understand the current situation of the enterprise and listen to the demands and suggestions.   In the seminar, Wayeal reported the development of the enterprise, the scientific research achievements and the future development plan. With the national "14th Five-Year Plan" and "Double Carbon" target, Wayeal actively responds to the needs of the country and enterprises, and launches "Digital Intelligence Double Carbon Integrated Solution", "Fine Particulate Matter - Ozone Synergy Control Solution", as well as comprehensive solutions in various scenarios such as air environment monitoring, water quality online monitoring, fixed pollution source monitoring and emergency monitoring.   During the exchange, President Guo Chengzhan affirmed the R&D strength and scientific research achievements of Wayeal, and highly praised its determination to attach importance to independent R&D and technological innovation in the past 20 years and insist on "not forgetting the original intention and replacing imports". He also said that with the high-quality development of ecological and environmental protection industry, the establishment of ecological and environmental monitoring and supervision system will slowly change from "human defense" to "technology defense". He hope that Wayeal will aim at the world's cutting-edge technology, play a leading role in the industry, adhere to scientific and technological innovation, and make greater contributions to the localization of high-end environmental monitoring instruments and equipment. After the meeting, Mr. Zang Mu, Chairman of Wayeal, took President Guo Chengzhan and his party to visit the exhibition hall, R&D lab and production workshop of Wayeal.