In recent years, with the rapid development of high-performance liquid chromatography, this method has become a widely used detection method in the current analysis of carbohydrates. It has the advantages of high resolution, good repeatability, and high accuracy. Check out the micro-source detection laboratory Literature data used high-performance liquid chromatography to detect rice seeds.

Using Chuangjie HPLC-MS for detection. Accurately weigh 0.03g of sucrose standard and place it in a volumetric flask, add an appropriate amount of ultrapure water, and dissolve it with ultrasound to adjust the volume. Then take a 25mL volumetric flask, weigh 5.0mL of the standard stock solution, add ultrapure water, and dilute to the mark to create a mixed standard solution. All standard solutions are stored in the refrigerator and removed and returned to room temperature before use. The soluble sugar solution of fresh rice seeds was used as the sample to be tested.

The mass spectrometry conditions used electrospray ionization negative ion collection mode; capillary voltage: 3.2kV; cone voltage of 20 V, extraction voltage: 4.0V to measure sucrose, radio frequency voltage: 0.5V, source temperature: 120°C, desolvation temperature: 300℃, desolvation gas: 300L/h, cone backflush gas: 10L/h. The retention time of sucrose is 7.89 min respectively.

The HPLC-MS method is used to detect sucrose components, which is fast, simple to operate, and accurate. The sensitivity of the determination is also greatly improved, providing a method reference for accurately detecting the sugar content in medicines and foods.

1. Ensure the instrument is in good condition. If necessary, replace washing solutions and waste liquids, clean injection needles, replace injection liners and spacers, and clean nozzles, etc.
2. Ensure the chromatography column to be used is in good condition, with a clean column head. If necessary, cut off 1-2 cm, and ensure the column efficiency is normal.
3. Understand the items to be detected, including control, purity, residual solvents, etc.
4. Understand the characteristics of the sample, such as solubility, stability, etc. For example, whether it is stable in the presence of water or alcohol, or whether it is prone to hydrolysis or ester exchange. Avoid using water, methanol, or ethanol as diluents for these compounds, and prefer acetonitrile as a diluent. Determine whether the compound is stable in acid or alkaline conditions. For example, Boc structures are not acid-resistant and require new liners. Determine whether the compound is stable at high temperatures, etc.
5. Determine the detection method based on the chemical structure and physical properties of the compound. If the compound has UV absorption, liquid chromatography (LC) is preferred for detection. If the compound does not have UV absorption, contains some carbon and hydrogen, and has good thermal stability, gas chromatography (GC) is preferred. When the limit of detection is low (several tens of ppm), LC-MS can be used for detection. Common compounds suitable for GC include those with a molecular weight of less than 150 and a boiling point of less than 350℃ (cannot be used for GC if it is greater than 400℃), containing a four-membered ring, five-membered ring, six-membered ring structure, and some bridged and fused-ring structures. If the compound is a salt, it needs to be injected after being freed. If the compound contains one or more carboxyl groups, its boiling point will increase significantly, and it may not be suitable for GC. If the compound contains both amino and carboxyl groups (such as amino acids), it generally has a high boiling point and cannot be detected by GC.

II. Method development ideas

1. If the compound is not highly polar, use the general methods for HP-5 and DB-624 (12 min or 20 min) for preliminary screening, with a longer running time preferred to ensure that all substances are completely eluted. Observe the peak height, peak shape, and separation degree.
2. If the peak height is too low, increase the peak height by changing the injection volume or increasing the sample concentration (1000-6000). The sample concentration for GC is generally greater than 20 mg/mL. Alternatively, adjust the split ratio to increase the response value (the larger the split ratio, the easier it is to cause split discrimination).
3. If the peak shape is not good, increase the column flow rate appropriately, increase the split ratio, and increase the tail blow gas flow rate to make the peak shape narrow and sharp. If there is front or tailing in the peak shape, replace the chromatography column with a higher polarity. If there is significant tailing of early eluting components, ensure that there is no gas leakage in the chromatography column installation. Then, lower the injection port temperature by 50°C or adjust the initial temperature of the program to be 10-25°C lower than the boiling point of the solvent (slower heating rate).
4. When the peak shape is good but the separation is not sufficient, and the two peaks are not separated, the column temperature can be adjusted, the flow rate can be lowered, and the temperature program can be adjusted to increase the ramp rate slowly.
5. When the peak height, shape, and separation are all acceptable, the durability of the method should be examined. The temperature of the injection port can be changed to check for substance residues at low temperatures and substance decomposition at high temperatures. The flow rate can be adjusted to see if it greatly affects the peak retention time, and if the impact is too great, it may lead to reduced separation. Finally, the LOQ, solution stability, and other confirmation methods should be performed.

There are six commonly used detectors in liquid chromatography

1.Ultraviolet-visible (UV-Vis) Detector
The UV-Vis detector is the most widely used detector in liquid chromatography, accounting for over 80% of applications due to its excellent sensitivity and resistance to temperature, flow rate, wind speed, humidity, and vibration changes. Its high sensitivity can detect up to 10-9g/mL (naphthalene methanol solution), and it can detect using elution mode with good repeatability.

The sensitivity of the UV-Vis detector depends on solvent effects, background absorption, and differential refractive index effects. Different solvents have their own cutoff wavelengths, and solvent quality affects the cutoff wavelength. Solvent quality is also related to UV absorption by impurities, dissolved oxygen, and buffer solutes. Background absorption reduces the linear range, and many solvents produce background absorption, so careful selection is necessary. Differential refractive index effects can cause false UV absorption changes, resulting in quantification errors and inaccurate spectral profiles, especially during gradient application.

2.Photodiode array (PDA) Detector
The PDA detector can collect both UV and visible spectral data while simultaneously obtaining chromatographic data, making it useful for purity verification and confirmation of chromatographic peaks. It can reprocess data at any wavelength and eliminate differential refractive index effects from hardware. PDA detector performance is typically evaluated in terms of chromatographic sensitivity, spectral sensitivity, and spectral resolution.

3.Refractive index (RID) Detector
The RI detector is a commonly used detector in liquid chromatography, and it can be combined with pumps, columns, and injectors to form gel permeation chromatography or high-speed liquid chromatography systems, or used as a stand-alone analytical instrument with an appropriate injection system. It can detect all solutes, including those that cannot be detected with selective detectors, such as high molecular weight compounds, sugars, and aliphatic hydrocarbons. Because different liquids have different refractive indices, this detector has high versatility and can be widely used in chemical, petroleum, pharmaceutical, and food fields.

4.Fluorescence Detector
The fluorescence detector is a commonly used detector in high-performance liquid chromatography. When the chromatographic fraction is irradiated with ultraviolet light, the sample components with fluorescent properties can be detected. Its characteristics include high selectivity, only responding to fluorescent substances, and high sensitivity, with a lowest detection limit of up to 10-12 g/ml, making it suitable for trace analysis of polycyclic aromatic hydrocarbons and various fluorescent substances. It can also be used to detect substances that do not fluoresce but can fluoresce after chemical reaction. For example, in phenol analysis, most phenols do not fluoresce, so they are first processed to become fluorescent substances before analysis.

The fluorescence detector’s filter can be classified as short-pass (allowing all wavelengths below a specific point to pass through), long-pass (allowing all wavelengths above a specific point to pass through), and band-pass (allowing all wavelengths within a specific range to pass through).

5.Electrochemical Detector
The principle of the electrochemical detector is that a current proportional to the concentration of the compound being tested can be generated as the compound is oxidized or reduced. It is generally used in special situations and is mainly used to determine ions with unstable chemical properties, such as ions that are easily oxidized or reduced.

The characteristic of this detector is its very high selectivity, as only electroactive substances that are easily oxidized or reduced can be detected. For example, even when high levels of chloride and sulfate coexist, the detection of other ions is not affected, as these two ions are not detected by the electrochemical detector.

6.Conductivity Detector
All ionized compounds and dissociable compounds in aqueous solutions can conduct electricity. The conductivity detector uses the change in the conductivity of the mobile phase of the liquid chromatography as a quantitative basis. The mobile phase carrying the sample passes through the flow cell, and the blank mobile phase generates a conductivity value. The conductivity value of the sample with the mobile phase added is subtracted from the conductivity of the mobile phase to obtain the conductivity value of the sample, which is proportional to the concentration of the sample being tested.

The conductivity detector uses a conductive solution as the medium, so a buffer solution is suitable as the mobile phase. However, this unavoidably increases the background baseline of the detector. Therefore, in ion chromatography without a suppressor column, most people use a low concentration of organic acids or organic acid salts as the mobile phase to reduce the background baseline.

The characteristic of this detector is its relatively simple structure and low sensitivity, making it unique for detecting ions. In summary, each type of detector has its own characteristics and different applicable ranges. We should choose the appropriate detector based on different usage environments to improve work efficiency.

If there is an excess of copper, it will not work either, it will cause serious damage to cell membranes and can cause copper toxicity, diarrhea, hair loss and other diseases.

Today, let’s learn how to detect copper in sewage? Generally, flame atomic absorption spectrometry is used for analytical determination. This detection method has high sensitivity, low detection limit, good selectivity and low interference.

Preparation before the test：

Test instrument: Flame atomic absorption spectrometer
Accessories: hollow cathode lamp
Reagent: Cu

Experimental method：

1.Set up the working parameters of the instrument according to the test requirements.

2.Make the standard curve and sample determination.
Add 1+1HNO3 to each of the four stoppered test tubes.
Detection of copper in water samples according to the standard curve.

3.Determination of absorbance of standard solution.
A.Open the computer and data software, enter the test parameters.
B.Start the test, after the computer display ready will have been pressed shallow to deep concentration.
C.The first with a plug test tube into the catheter of the nebulizer.
D.Wait for the computer reading to stabilize, press the start button to determine.
E.After the computer reading is stable again, remove the test tube and put it into the next test tube.

4.Unknown water samples in the determination of copper ion concentration.
A.The same as the above steps, after the measurement of the last standard test tube into the water sample test tube.
B.To be read and stable to start the measurement, again to be read and stable computer that can be obtained after the graph.
C.Save all the above data and graphs to the designated location for processing and analysis.

1.The choice of gas chromatography column efficiency good column.
1.1According to the test conditions and sensitivity, select the appropriate filled column.
1.2 When buying the filled column, you can choose a reputable manufacturer to buy.

2.The use of high-purity carrier gas.
2.1 Such as helium, high purity hydrogen, etc. are available to improve the sensitivity of the detector.
2.2The cost of this method may be relatively high, while there are certain restrictions on the sensitivity.

3.Increase the flow of air, hydrogen.
Under certain experimental conditions, improve the flow of air, hydrogen, can make the sample in the detector fully combustion.

4.For the gas chromatograph TCD detector plus bridge flow.

5.For the FID detector to change the attenuation range.

6.Increasing the flow rate of the carrier gas can improve the sensitivity of the instrument.

7.Changing the parameters so that the slope is reduced.

Application of high performance liquid chromatography in the detection of drug content:

Drugs have a great relationship with the improvement of human health and quality of life. Due to the influence of purity, the efficacy of many drugs cannot be fully played, and even produce toxic side effects. Sometimes all kinds of tests need to be done before taking, which brings a lot of trouble. The detection of high performance liquid chromatography is relatively simple, which is the best choice for separating and purifying drugs. Because high performance liquid chromatography has the characteristics of high sensitivity, rapid simplicity and specificity, widely used in drug analysis, especially in the time of more interference performance than other methods.

Application of high performance Liquid chromatography in the detection of pharmaceutical wastewater:

The environmental pollution caused by residual drug components in pharmaceutical wastewater is becoming more and more serious. The treatment of pharmaceutical wastewater has become a very important aspect of environmental protection. High performance liquid chromatograph can simultaneously determine the content of crosssalamycin, theophylline and paracetamol in pharmaceutical wastewater, through the detection of pharmaceutical wastewater, to find a suitable way to remove harmful substances in pharmaceutical wastewater.

We are a branch of Kejie holding group, in charge of the overseas marketing of Kejie products, providing to customers with chromatograph, mass spectrometry, spectrum and other analytical scientifc instruments and professional services all around the world.Welcome to visit our website: www.changior.com or contact us via email: sales@changior.com

Conceptual distinction ：
First, the simple distinction between ICP-AES and ICP-OES. OES Optical Emission Spectrometry; Aes-atomic Emission Spectrometry both are inductively coupled plasma Emission Spectrometry, but they are called differently in different periods.It is more scientific and accurate to call ICP-OES because not only atomic but also ion lines are used in plasma emission spectroscopy. Note: Comparison of ICP-OES is made below.

Followed by ICP-OES and ICP-MS. For those who have a background in ICP-OES technology, ICP-MS is a plasma detector (ICP) with a mass spectrometer as the detector, while mass spectrographers think that ICP-MS is a mass spectrometer with an ICP as the source.

Finally, AAS and ICP-MS. AAS is atomic absorption spectrum, because it only uses monochromatic light irradiation in atomic spectrum, so it can only detect the content of one element, but the detection limit is relatively low and the reproducibility is good. ICP-OES is atomic emission spectrum, detection of multiple lines in the atomic spectrum, the detection limit is relatively low, and multi-channel can simultaneously detect a variety of atoms and ions. It’s convenient and reproducible. ICP-MS is ICP mass spectrometry, using mass spectrometry to detect isotope content to detect the content of elements, the detection limit is the lowest, the effect is the most ideal.

Performance difference ：
Application: AAS is used for the detection of known element content; ICP can be used for both known and unknown, and is suitable for multielement analysis. ICP-MS is generally used for standard measurements because it is more expensive and has the lowest detection limit.

1. Detection limit
The detection limit of ICP-MS is very impressive, most of the detection limit of its solution is PPT level (it must be remembered that the actual detection limit can not be better than the cleaning conditions of your laboratory), the detection limit of graphite furnace AAS is subPPB, and the detection limit of most elements of ICP-OES is 1-10ppb. Some elements can also be detected in clean samples with remarkable sub-PPB detection limits.

It must be pointed out that the PPT-level detection limit of ICP-MS is for simple solutions with few dissolved substances. If the detection limit of solid concentration is involved, the advantages of ICP-MS detection limit will be reduced by as much as 50 times due to the poor salt tolerance of ICP-MS. Some common light elements (such as S, Ca, Fe, K, Se) have serious interference in ICP-MS, which will also worsen its detection limit.

2.Interference
These three techniques present different types and complex interference problems, and for this reason, we discuss each technique separately. Interference of ICP-MS: mass spectrum interference, matrix acid interference, double charge ion interference, matrix effect, ionization interference, space charge effect. ICP-OES interference: spectral interference, matrix effect, ionization interference. GFAAS interference: spectral interference, background interference, gas phase interference, matrix effect.

3. Ease of use
In daily work, ICP-OES is the most mature in terms of automation and can be used by unskilled personnel.
The operation of ICP-MS has been complex until now. Although there have been great advances in computer control and intelligent software since 1993, it still needs to be fine-adjusted by technicians before routine analysis. The study of ICP-MS methods is also complex and time-consuming. The routine work of GFAAS is relatively easy, but the formulation of methods still requires considerable skill.

4. Total solid solubility TDS in the sample
In routine work, ICP-OES can analyze solutions of up to 10%TDS and even up to 30% salt solutions. ICP-MS can analyze 0.5% solution in a short period of time, but most analysts are happy to use solutions up to 0.2%TDS. When the original sample is solid, ICP-MS requires a higher dilution ratio than ICP-AES and GFAAS, so it is not surprising that its conversion to the detection limit in the original solid sample does not show a great advantage.

5. Linear dynamic range LDR
ICP-MS has LDR in excess of 105, and various methods can develop LDR up to 108. However, for ICP-MS: high matrix concentration can cause many problems, and the best solution to these problems is dilution. For this reason, the main area of application of ICP-MS is in trace/ultra-trace analysis.

The LDR of GFAAS is limited to 102 ~ 103, and a higher concentration can be analyzed if a subsensitive line is selected. ICP-OES has more than 105 LDR and strong salt resistance, which can be used for the determination of trace and major elements. The concentration of ICP-OES can be determined as high as percentage content. Therefore, ICP-OES plus ICP-MS or GFAAS can meet the needs of laboratory well.

6. Precision
The short-term precision of ICP-MS is generally 1 ~ 3% RSD, which is obtained by using multiple internal standard methods in routine work. Long-term (several hours) precision is less than 5%RSD. Good accuracy and precision can be obtained by using isotope dilution methods, but the cost of this method is too high for conventional analysis.

The short-term precision of ICP-OES is generally 0.3 to 2%RSD, and the long-term precision of several hours is less than 3%RSD. The short-term precision of GFAAS ranges from 0.5 to 5%RSD. The long-term precision depends not on time but on the number of graphite tubes used.

7. Sample analysis ability
ICP-MS has an amazing ability to analyze large numbers of samples for the determination of trace elements, typically in less than 5 minutes per sample, and in some cases in as little as 2 minutes. Our laboratory believes that the main advantage of ICP-MS is its analytical capability.

The analysis speed of ICP-OES depends on whether full-spectrum direct reading type or single-channel scanning type is used. The time required for each sample is 2 or 6 minutes. Full-spectrum direct reading type is faster, usually 2 minutes for each sample.The analysis speed of GFAAS is 3-4 minutes for each element in each sample, and it can work automatically at night to ensure the analysis ability of samples.

8.Unmanned control operation
The ICP-MS, ICP-OES, and GFAAS can operate unattended overnight due to their modern automated design and safety using inert gases.

9. Operating costs
The start-up cost of ICP-MS is higher than that of ICP-OES because some components of ICP-MS have a lifetime and need to be replaced, including turbo molecular pumps, sampling cones and intercepting cones, and detectors. For ICP-MS and ICP-OES, the life of the atomizer is the same as that of the torch.

If the lab has chosen ICP-OES in place of ICP-MS, it is best to have GFAAS in the lab. GFAAS shall calculate the cost of its graphite tubes. Among the above three technologies, the cost of Ar gas is a similar budget, and the Ar cost of ICP technology is much higher than that of GFAAS.

We are a branch of Kejie holding group, in charge of the overseas marketing of Kejie products, providing to customers with chromatograph, mass spectrometry, spectrum and other analytical scientifc instruments and professional services all around the world.Welcome to visit our website: www.changior.com or contact us via email: sales@changior.com

We provide analytical instruments with the latest technology in the world, provide professional solutions for scientists and laboratory analysts in GC, GCMS, LC, AAS, ICP, UV and other fields, and provide technical support in their daily testing, help researchers to do a variety of scientific analysis, assist enterprises to develop testing products. We will assist the government and other regulatory and testing institutions in providing analysis and testing services. Kejie Holdings group provides customers around the world with high-quality technical support and overall service solutions with the leading scientific analytical instruments.

At present, due to the needs of global business development, we are looking for: analytical instrument engineers to join the cooperation to serve the local market. The specific requirements are as follows:

Position: Analytical Instrument Engineer
Number of hires: 35
Job nature: full-time or part-time
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Job Responsibilities:
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Job Requirements:
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Pay and description: who are interested in joining, can send email to contact us, and attach your resume, please send email: E-mail: service@changior.com we receive your email will be the first time to get in touch with you, negotiate specific cooperation matters.

1.Avoid sharp changes in pressure and temperature
A sudden change in temperature or the column falling from the height will affect the filling condition of the column; The sudden increase or decrease of the column pressure will also impulse the column packing, so the flow rate should be adjusted slowly to maintain the stability of the column packing.

2. Avoid changing the composition of the solvent directly
In the need to change the composition of the test sample solution, the composition of the solvent should be gradually changed, especially in reverse phase chromatography, should not be directly changed from organic solvents to all water, and vice versa. When the column is rinsed with the eluent with high secondary elution capacity, the displacement of mobile phase in the flow path system should be gradually transited to miscible solvent, and the volume of each mobile phase should be about 20 times of the column volume, that is, 50~75ML is required for conventional analysis.

3. Avoid column recoil
Generally speaking, the column can not recoil, only the column can recoil to remove impurities left on the column head. Otherwise, the effect of recoil column is to rapidly reduce column efficiency.

4. Avoid damage to stationary phase due to improper use of mobile phase
Choose the appropriate mobile phase (especially PH) to avoid damage to the stationary phase. Sometimes a pre-column can be attached to the front of the sampler. If the analytical column is bonded to silica gel, the pre-column is silica gel to “saturate” the mobile phase prior to entering the analytical column, preventing the silica matrix from being dissolved in the analytical column.

5. It is forbidden for samples to enter the column directly without treatment
To avoid injecting complex matrix samples, especially biological samples, directly into the column, it is necessary to preprocess the sample or connect a guard column between the sampler and the column. The guard column is usually a short column filled with a similar stationary phase. Guard posts can and should be replaced frequently.

6. Do not store buffer solution in the column for a long time
The column should be filled with acetonitrile or methanol when preserving the column, and the column joint should be tightened to prevent solvent evaporation and drying. It is absolutely forbidden to leave the buffer solution in the column overnight or for longer periods.

7. It is forbidden to seal chromatographic column directly without treatment
Suitable solvent should be used to clean the column after completion of use, for example, ODS column should be washed with methanol to the baseline balance; When salt buffer solution is used as mobile phase, salt-free mobile phase flushing should be applied after use. Compounds containing halogen elements (fluorine, chlorine, bromine) may corrode stainless steel pipes, and should not be contacted for a long time; The chromatographic column installed in the liquid chromatograph should be flushed for 15 minutes every 4-5 days if it is not often used.

We are a branch of Kejie holding group, in charge of the overseas marketing of Kejie products, providing to customers with chromatograph, mass spectrometry, spectrum and other analytical scientifc instruments and professional services all around the world.Welcome to visit our website: www.changior.com or contact us via email: sales@changior.com

The routine maintenance of AAS is the responsibility of every analyst. This work can be summed up in the following aspects.The routine maintenance and maintenance of atomic absorption spectrometer is as follows:

1.Hollow cathode lamp lamp window should be kept clean, accidentally contaminated, can be wiped with alcohol cotton.
2.Regularly check whether the gas supply pipeline leakage. When checking, you can apply some soapy water in suspicious places to see if there are bubbles. Do not check air leakage with open fire.
3.In the air compressor supply pipeline, should be installed gas and water separator, often discharge condensate water accumulated in the gas and water separator.
4.Keep the fog room clean and discharge fluid unobstructed.
5.Salt deposits in the seam of the burner will make the flame bifurcate and affect the measurement results. If necessary, it can be washed with water.
6.The determination solution should be filtered or thoroughly clarified to prevent clogging of the nebulizer.
7.Do not touch the lens of the external optical path with your hands.
8. The grating and mirror in the monochromator are mostly coated devices on the surface, which are easy to be contaminated by damp, so the monochromator should be kept sealed and dry.
9.The atomic absorption spectrometer used for a long time, because its internal dust too much sometimes lead to circuit failure; If necessary, the ear ball can be blown clean or brushed with a hair brush.
10.The instrument that is not used for a long time should be kept dry and energized regularly in the wet season.

We are a branch of Kejie holding group, in charge of the overseas marketing of Kejie products, providing to customers with chromatograph, mass spectrometry, spectrum and other analytical scientifc instruments and professional services all around the world.Welcome to visit our website: www.changior.com or contact us via email: sales@changior.com