[Chemical Knowledge]：Detection method and analysis technology of benzyl alcohol

Benzyl alcohol (BenzylAlcohol) is a colorless and transparent liquid with a faint aromatic odor, which is widely used in medicine, spices, chemical and other fields. Because of its importance, the detection and analysis of benzyl alcohol is particularly critical. How can we detect benzyl alcohol efficiently and accurately? This article will introduce the main detection methods and analysis techniques of benzyl alcohol in detail.

1. gas chromatography (GasChromatography,GC)

Gas chromatography is a commonly used method for the analysis of organic compounds. Its principle is to separate the sample by the distribution equilibrium between the stationary phase and the mobile phase. For benzyl alcohol, gas chromatography has the advantages of high sensitivity, strong selectivity and fast analysis speed.

1. Sample preparation: The benzyl alcohol sample is diluted to an appropriate concentration by a solvent, usually high-purity ethanol or n-hexane is selected as the solvent.

2. Instrument conditions: capillary column is used, column temperature is set to 100-250 ℃, inlet temperature is set to 200-250 ℃, and detector (such as flame ionization detector, FID) temperature is set to 250-300 ℃.

3. Analysis process: The sample is injected into the gas chromatograph, separated by the column and detected by the detector, and finally the chromatogram and peak area of benzyl alcohol are obtained.

2. high performance liquid chromatography (High-PerformanceLiquidChromatography,HPLC)

High performance liquid chromatography is a liquid phase analysis method suitable for the analysis of thermally unstable and high molecular weight compounds. For benzyl alcohol, high performance liquid chromatography also has high sensitivity and selectivity.

1. Sample preparation: The benzyl alcohol sample is diluted to an appropriate concentration, usually methanol or acetonitrile is selected as the solvent.

2. Instrument conditions: using C18 reverse phase column, the mobile phase can choose water-methanol or water-acetonitrile gradient elution, the flow rate is set to 1.0 mL/min, the detection wavelength is 254nm.

3. Analysis process: the sample is injected into HPLC, separated by the interaction of mobile phase and stationary phase, and finally detected by ultraviolet detector (UV) to obtain the chromatogram and peak area of benzyl alcohol.

3. UV-Vis Spectrometry (Ultraviolet-VisibleSpectroscopy,UV-Vis)

Ultraviolet-visible spectroscopy is an analytical method based on the absorption characteristics of molecules in ultraviolet or visible light, which is suitable for the determination of the concentration of benzyl alcohol.

1. Sample preparation: Dilute the benzyl alcohol sample to the appropriate concentration, usually choose ethanol or water as the solvent.

2. Instrument conditions: The absorbance of benzyl alcohol at 254nm was measured using an ultraviolet-visible spectrophotometer with a scanning wavelength range of 200-400nm.

3. Analysis process: put the sample into the cuvette, scan the spectrum, record the absorbance, and calculate the concentration of benzyl alcohol in the sample by comparing the standard curve.

4. mass spectrometry (MassSpectrometry,MS)

Mass spectrometry is a technique for analysis by determining the mass-to-charge ratio of molecular ions, which can provide molecular weight information and structural information of benzyl alcohol.

1. Sample preparation: Dilute the benzyl alcohol sample to an appropriate concentration, usually selecting a high-purity solvent.

2. Instrument conditions: use electron ionization (EI) or electrospray ionization (ESI) as the ion source, the mass analyzer selects quadrupole or time of flight analyzer (TOF), and the detector uses an ion counter.

3. Analysis process: the sample is introduced into the mass spectrometer through the sample inlet, and the molecular ions are ionized by the ion source. After separation by the mass analyzer, the detector records the signal and obtains the mass spectrum of benzyl alcohol.

5. nuclear magnetic resonance spectroscopy (NuclearMagneticResonanceSpectroscopy,NMR)

Nuclear magnetic resonance spectroscopy is an analytical method based on the spin properties of atomic nuclei, which can provide detailed structural information of benzyl alcohol.

1. Sample preparation: The benzyl alcohol sample is dissolved in a deuterated solvent (such as deuterated chloroform, CDCl3), and the concentration is usually 10-20 mg/mL.

2. Instrument conditions: using high resolution nuclear magnetic resonance spectrometer, common hydrogen spectrum (1H-NMR) and carbon spectrum (13C-NMR).

3. Analysis process: the sample is placed in the NMR tube, put into the NMR instrument, excite the nuclear spin by radio frequency pulse, record the nuclear magnetic resonance signal, analyze the chemical shift, coupling constant, etc., and obtain the NMR spectrum of benzyl alcohol.

6. infrared spectroscopy (InfraredSpectroscopy,IR)

Infrared spectroscopy is a method based on the analysis of the absorption characteristics of molecules to infrared light, which is suitable for the qualitative analysis of benzyl alcohol.

1. Sample preparation: The benzyl alcohol sample is mixed with KBr and pressed into tablets, or the sample is directly dropped on the ATR crystal surface.

2. Instrument conditions: using Fourier transform infrared spectrometer (FT-IR), scanning range of 4000-400cm-1, resolution of 4cm-1.

3. Analysis process: Put the sample into the IR instrument, irradiate the sample by infrared light, record the absorption spectrum, and determine the presence of benzyl alcohol according to the characteristic absorption peak.

In conclusion, the detection methods and analysis techniques of benzyl alcohol are varied, and each method has its unique advantages and application scenarios. Gas chromatography and high performance liquid chromatography are suitable for the quantitative analysis of benzyl alcohol with high sensitivity; ultraviolet-visible spectroscopy is suitable for the rapid determination of benzyl alcohol concentration; mass spectrometry and nuclear magnetic resonance spectroscopy can provide detailed molecular weight and structure information; infrared spectroscopy is suitable for the qualitative analysis of benzyl alcohol. Selecting the appropriate method according to the actual needs can achieve efficient and accurate detection of benzyl alcohol.