CN103604792A - Resonance Rayleigh scattering (RRS) method for measuring bromide ion - Google Patents

Abstract

The invention discloses a resonance Rayleigh scattering spectrometry method for measuring ^Br- , which comprises the following steps: (1) preparing a Br ^- standard solution system; (2) preparing a blank control solution system; (3) measuring Br ^- standard solution systems respectively and the resonance Rayleigh scattering peak intensity value I _standard and I _blank of the blank control solution system, calculate Δ I = I _standard – I _blank ; (4) make a working curve with the concentration relationship between Δ I and ^Br- ; (5) the measured For the determination of the substance sample, calculate ΔIsample = Isample - Iblank ; (6) According to the measured _ΔIsample of the _sample , check the working _curve in step (4 ₎ , and calculate the content of ^Br- in the analyte. The instrument of the determination method is simple, the operation is fast, the sensitivity is high, and the selectivity is good.

Description

A Resonant Rayleigh Scattering Method for Measuring Bromide Ions

technical field

The invention relates to the field of analytical chemistry, in particular to a resonance Rayleigh scattering spectrometry for determining bromide ions.

Background technique

Bromine is a trace element that widely exists in nature and is necessary for human body. According to reports, the lack of bromide ions will slow down the growth of animals, and at the same time cause skin rashes, bromide poisoning, central nervous system failure, mental deterioration and acne and other diseases. For example, the concentration of bromide ions (Br ^- ) in mental patients is often low; It also plays an important role in sewage treatment and searching for oil fields. However, the analysis of bromide ions has always been a relatively weak research topic, especially for the determination of low-content bromine. In recent years, with the enhancement of environmental ecological awareness, more and more attention has been paid to the environmental function and nutritional function of Br ^- . In addition, with the extensive use of bottled drinking water, the by-product bromate produced by the disinfection of bromide in the water is potentially carcinogenic, and excessive consumption can damage human blood, central nervous system and kidneys. Therefore, establishing a high-sensitivity, high-selectivity, and low-cost detection method for Br ^- is of great significance to environmental protection and human health.

At present, the methods for determining Br ^- mainly include spectrophotometry, inductively coupled plasma mass spectrometry, cyclic voltammetry, fluorescence and ion chromatography. The neutron activation method is considered to be the method with the highest sensitivity, and it is also a method commonly used at home and abroad to determine the bromine content in rock ore, but it is expensive and difficult to carry out widely; Not high; the selectivity of inductively coupled plasma mass spectrometry is good, but the experimental process is complicated and the equipment is expensive. The sample preparation is complicated; the interference of cyclic voltammetry is large, and the linear range is small; the X-ray fluorescence method can check several halogens at the same time, but the method is more complicated and the sensitivity is lower. Therefore, it is necessary to establish a simple and sensitive method for the determination of Br ^- . To the best of our knowledge, the detection of bromide ions by resonance Rayleigh scattering spectroscopy has not been reported.

Contents of the invention

The object of the present invention is to provide a simple and rapid resonance Rayleigh scattering spectrometry method for determining ^Br- .

A kind of resonance Rayleigh scattering spectrometry method of measuring ^Br- , comprises the steps:

(1) Prepare Br ^- standard solution system: Take a 5 mL graduated test tube, pipette 1-100 μL 1.0 μg/mL Br ^- standard solution, 50-100 μL 1.0× ^10-5 mol/L fluorescein, mix well, add 100-180 μL 0.160 mol/L H ₂ O ₂ , then add 150-250 μL 3.0 mol/L HCl, dilute to 2.0 mL with twice distilled water, mix well, let stand for 40 min, then add 400-600 μL 500 g /L NH ₄ AC, stand for 5min;

(2) Prepare a blank control solution system: prepare a blank control solution system without adding Br ^- standard solution by the method of step (1);

(3) Take an appropriate amount of the Br ^- standard solution system and blank control solution system prepared according to steps (1) and (2) respectively, place them in a cuvette, and scan the excitation wavelength and emission wavelength synchronously on the fluorescence spectrophotometer, Obtain the resonance Rayleigh scattering spectrum of the system, measure the resonance Rayleigh scattering peak intensity value I of the Br ^- standard solution system at the maximum wavelength of the system at 360 nm, and measure the resonance Rayleigh scattering peak intensity value I _b of the blank control solution system, and calculate Δ I = I _{- Ib} ;

(4) Make a working curve based on the concentration relationship between ΔI and ^Br- ;

(5) Determination of the sample of the analyte: take the analyte containing Br ^- , then pipette a certain amount to replace the Br ^- standard solution, and operate according to steps (1) to (3). Calculate the Δ I _sample of the measured object = I _sample - I _b ;

(6) According to the ΔI _sample measured in the sample, look up the working curve in step (4), and calculate the concentration of Br ^- in the analyte.

The principle of realizing the present invention is: under acidic conditions, H ₂ O ₂ oxidizes ^Br- to Br ₂ , and Br ₂ reacts with fluorescein to generate eosin, which further aggregates to form larger particles, and produces a resonance Rayleigh at 360 nm Scattering peak, and the intensity of the resonance Rayleigh scattering peak increases linearly with the Br ^- concentration, so the Br ^- content can be determined by resonance Rayleigh scattering spectroscopy.

The advantages of the invention are: compared with the existing methods, the determination method has the advantages of simple operation, high sensitivity and good selectivity.

Description of drawings

Fig. 1 is a partial resonance Rayleigh scattering spectrum diagram for measuring ^Br- in an embodiment of the present invention.

In the figure: a: 3×10 ^-7 mol/L fluorescein-1.89×10 ^-2 mol/L H ₂ O ₂ -0.36 mol/L HCl-80 g/L NH ₄ AC; b: a+10 ng/mL Br ^- ; c: a+25 ng/mL Br ^- ; d: a+50 ng/mL Br ^- .

Detailed ways

Example:

The application of resonance Rayleigh scattering spectrometry to determine Br ^- includes the following steps:

(1) Prepare Br ^- standard solution system: Take a 5 mL graduated test tube, pipette 1, 10, 20, 50, 100 μL 1.0 μg/mL Br ^- standard solution, 75 μL 1.0× ^10-5 mol/L fluorescein, Mix well, add 150 μL 0.160 mol/L H ₂ O ₂ , then add 200 μL 3.0 mol/L HCl, distill the volume to 2.0 mL with twice distilled water, mix well, let stand for 40 min, then add 500 μL 500 g/L NH ₄ AC, let stand for 5min;

(2) Prepare a blank control solution system: prepare a blank control solution system without adding Br ^- standard solution by the method of step (1);

(3) Take an appropriate amount of the Br ^- standard solution system and blank control solution system prepared according to steps (1) and (2) respectively, place them in a cuvette, and scan the excitation wavelength and emission wavelength synchronously on the fluorescence spectrophotometer, Obtain the resonance Rayleigh scattering spectrum of the system, measure the resonance Rayleigh scattering peak intensity value I of the Br ^- standard solution system at the maximum wavelength of the system at 360 nm, and measure the resonance Rayleigh scattering peak intensity value I _b of the blank control solution system, and calculate Δ I = I _{- Ib} ;

(4) Make a working curve based on the concentration relationship between ΔI and ^Br- ;

(5) Determination of analyte samples: Take river water and well water samples, filter impurities with filter paper, then take an appropriate amount of filtrate to replace Br ^- standard solution, and operate according to steps (1) to (3). Calculate the Δ I _sample of the measured object = I _sample - I _b ;

(6) According to the ΔI _sample measured in the sample, check the working curve in step (4) and calculate the ^Br- content in the tested sample to be 856 ng/mL and 324 ng/mL.

Verification of detection method of the present invention:

Take the water sample in step (5) according to the reference: Tang Shiming, Yu Jianfeng, Yuan Cunguang. Determination of bromide ions in brine by dual-wavelength spectrophotometry. Salt Industry and Chemical Industry, 2012, 7(7): 16-18. Br ^- content in water, the calculated Br ^- content in water is 852 ng/mL, 319 ng/mL. The measurement results are consistent with the method of the present invention.

The range of ^Br- content measured in the embodiment of the present invention is 0.5-50 ng/mL, and the regression equation is ΔI =35.5C+149.5.

Claims (1)

1. a kind of measuring Br ^- resonance Rayleigh scattering spectrometry, comprises the steps: (1) Prepare Br ^- standard solution system: Take a 5 mL graduated test tube, pipette 1, 10, 20, 50, 100 μL 1.0 μg/mL Br ^- standard solution, 75 μL 1.0× ^10-5 mol/L fluorescein, Mix well, add 150 μL 0.160 mol/L H ₂ O ₂ , then add 200 μL 3.0 mol/L HCl, distill the volume to 2.0 mL with twice distilled water, mix well, let stand for 40 min, then add 500 μL 500 g/L NH ₄ AC, let stand for 5min; (2) Prepare a blank control solution system: prepare a blank control solution system without adding Br ^- standard solution by the method of step (1); (3) Take an appropriate amount of the Br ^- standard solution system and blank control solution system prepared according to steps (1) and (2) respectively, place them in a cuvette, and scan the excitation wavelength and emission wavelength synchronously on the fluorescence spectrophotometer, Obtain the resonance Rayleigh scattering spectrum of the system, measure the resonance Rayleigh scattering peak intensity value I of the ^Br- standard solution system at the maximum wavelength of the system at 360 nm, and measure the resonance Rayleigh scattering peak intensity value I _b of the blank control solution system, and calculate Δ I = I _{- Ib} ; (4) Make a working curve based on the concentration relationship between ΔI and ^Br- ; (5) Determination of the sample of the analyte: take the analyte containing Br ^- , then pipette a certain amount to replace the Br ^- standard solution, and operate according to steps (1) to (3) to calculate _{the Δ Isample} of the analyte = I _{sample -Ib} ; (6) According to the ΔI _sample measured in the sample, look up the working curve in step (4), and calculate the concentration of Br ^- in the analyte.

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