SU1363031A1 - Method of determining oxygen in gases - Google Patents

Abstract

The invention relates to the field of analytical chemistry (the field of luminescent analysis of inorganic substances) and can be used to determine trace amounts of oxygen in gases. The goal is to increase the detection sensitivity. The method includes sorption of dyes on silica in the amount of 7-10 -3 IO and measuring the linear increase in the intensity of the delayed fluorescence of the sorbent surface. о S (Л с со О5 со

Description

The invention relates to analytical chemistry, in particular to the luminescent analysis of inorganic substances, and can be used to determine the trace oxygen in gases.

The purpose of the invention is to increase the sensitivity of the determination of oxygen in

tick in coordinates Ij {g - oxygen concentration, µg / l.

The lower limit of the determined oxygen content is 0.17 µg / l. In the range of oxygen concentrations of 0.17–440 µg / l, the calibration characteristic is a straight line, and the intensity is slow.

concentration range 0.17-440 µg / l. d fluorescence increases 90 times. When the content of the dye is less, the sensitivity coefficient is

The sensitivity is determined and increased.

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the lower limit of the determined oxygen content. When the content of the dye is greater than 3 S, the detection sensitivity decreases and the dependence of the intensity of the delayed fluorescence on the oxygen concentration is nonlinear.

The intensity of the delayed fluorescence was measured on a setup consisting of a quartz cell 1 mm thick, where silica (0.1 g) with a dye sorbed on it was placed, a laser stimulus source of LPRP-4 operating in the Q-switched mode with an IZ-25 amplifier (energy 150 mJ at ff 1060 nm) and a frequency doubler based on niobate lithium (530 nm), an FEU-84 photoelectric multiplier with an electric photo gate with a resolution of 50 n and an S8-13 oscilloscope. I

Example 1. To O, 2 g of Silochrom C-80 brand silica (fraction 0.2-0.3 mm) in a cup, add 5 ml of a 1M M acridine orange solution and mix for 5 minutes. The colorless liquid above the sorbent is drained and the sorbent is dried in air at room temperature. 0.1 g of the obtained sorbent (dye content 2.5.10) is placed in a cuvette, which is attached to a vacuum post with a forevacuum and diffusion steam-oil pump with a nitrogen trap, and is pumped out to a cuvette up to 5 1 O mm Hg. The dosing of oxygen into the cuvette is carried out by adding air (at a known temperature and pressure) from small, precisely measured volumes. The ratio of the air introduced into the system to the volume of the cuvette is determined in advance. The intensity of the delayed fluorescence (I () at the maximum of its luminescence (X 520 nm) is measured and a calibration characteristic is plotted

45

0.049.

The sensitivity coefficient does not change when the content of 15 acridine orange varies in the range of 7-10 -3 -10-M, g-.

Example 2. KO, 2 g of silica grade Silichrome C-80 is added 5 ml of a 110 M solution of trypaflavin (one of the representatives of acridine dyes). Next, proceed as described in Example 1, and a sorbent is obtained with a dye content of 2.510 M-g. The intensity of the delayed fluorescence increases with a change in the oxygen concentration in the range of 0.17–440 µg / l and increases by a factor of 90. In this range of oxygen concentrations, the calibration characteristic is 30 straight lines. The sensitivity coefficient is 0.049. The lower limit of detectable oxygen content is 0.17 µg / l.

For acridine yellow, the above numerical values are similar. .

PRI me R 3. Determination of oxygen in high purity helium gas. A sorbent is prepared as described in Example 1. The cuvette is evacuated, the analyzed gas is passed through the sorbent at atmospheric pressure, and the intensity of the slow fluorescence is measured. The oxygen content is found according to the calibration characteristic, the construction of which is described in Example 1.

Found oxygen, µg / l: 1,3 ± + 0,1-, p 5.

50 Thus, the proposed method, unlike the known ones, allows a 2.5-fold increase in the sensitivity of the determination of oxygen. In addition, the method is characterized by high reproducibility of the analysis results — the minimum value of the relative standard deviation is 0.05. The dye sorbent retains its characteristics at least in te

40

tick in coordinates Ij {g - oxygen concentration, µg / l.

The lower limit of the determined oxygen content is 0.17 µg / l. In the range of oxygen concentrations of 0.17–440 µg / l, the calibration characteristic is a straight line, and the intensity is slow.

0

five

0.049.

The sensitivity coefficient does not change when the content of 5 acridine orange varies in the range of 7-10 -3 -10-M, g-.

Example 2. KO, 2 g of silica grade Silichrome C-80 is added 5 ml of a 110 M solution of trypaflavin (one of the representatives of acridine dyes). Next, proceed as described in example 1, and get the sorbent with a dye content of 2.510 M-g. The intensity of the delayed fluorescence increases with a change in the oxygen concentration in the range of 0.17–440 µg / l and increases by a factor of 90. In this range of oxygen concentrations, the calibration characteristic is a straight line. The sensitivity coefficient is 0.049. The lower limit of detectable oxygen content is 0.17 µg / l.

For acridine yellow, the numerical values given above are similar. .

PRI me R 3. Determination of oxygen in high purity helium gas. A sorbent is prepared as described in Example 1. The cuvette is evacuated, the analyzed gas is passed through the sorbent at atmospheric pressure, and the intensity of the slow fluorescence is measured. The oxygen content is found according to the calibration characteristic, the construction of which is described in Example 1.

Found oxygen, µg / l: 1,3 ± + 0,1-, p 5.

0 Thus, the proposed method, unlike the known ones, allows a 2.5-fold increase in the sensitivity of the determination of oxygen. In addition, the method is characterized by high reproducibility of the analysis results — the minimum value of the relative standard deviation is 0.05. The dye sorbent retains its characteristics at least in te

0

- 13630314

half a year. With one sample of sor dyes on silica and measurement

 bent can be performed at least luminescence surface of the sorbent,

re two thousand chi analyzes. The method is characterized in that, with

It is characterized by high selectivity - the purpose of increasing the sensitivity to the determination of trace amounts of oxygen and oxygen in the range of oxygen is interfered with by nitrogen and helium. concentration of 0.17-440 µg / l dye

Claims (1)

injected into the sorbent in the amount of 7-10 - Claim 1. - , - 3--10 M-g, and measuring the linear increase in oxygen in quenching the intensity of the delayed charge, including the sorption of acridine fluorescence. I