SU1608575A1 - Flame-ionization detector - Google Patents

Abstract

The invention relates to gas chromatography, a detection device for gases and vapors, and can be used in chromatographs and other analytical instruments. The purpose of the invention is to increase the sensitivity and expansion of the linear dynamic range of the detector. In the detector case there are a burner serving as a potential electrode, a collector electrode in the form of a truncated cone, facing a large base to the burner, which ensures good gas dynamics of the detector, and an ignition element. The burner and the ignition element are alternately connected to the power sources via an electrical switch. The ignition element is mounted along the axis of the collector electrode from the side of the smaller base of the cone. 1 ill., 1 tab.

Description

cl

with

we shall beat Gikh Ana /

Whole

sensation

On

and he

Det

air inspecting performed

Directed burner cer 10, laying

The invention relates to detecting devices for gases and vapors and can be used in chromatographs and other instruments. The aim of the invention is to improve and extend the linear range of the detector.

The image shows a flame ionization detector.

It consists of a housing, including 1 and a cover 2. At the base there are channels for introducing hydrogen 3 and 4 and the analyzed gas from the chromatographic column 5. On the base there are burners 6 and a diffuser 1 for directing air into the combustion zone, includes a nozzle 8 , the insulator 9 and the screwed into the base through the pro 1. On the lid 2 through the passage

The insulators 12 and 13 secure the collector electrode 14 and the outlet 15 of the burner 6, which serves as a potential electrode, and the ignition coil 18 is fixed through the bushing insulators 16 and 17. An insulated switch 19 is connected to the insulated leads of coil 18, providing alternate connection of the burner 6 and ignition coil 18 to grounded power supply sources 20 and 21, respectively.

The detector works as follows.

Hydrogen through channel 3 enters the burner 6, the air to maintain combustion enters from channel 4 and, after passing through the diffuser 7, is directed to the combustion zone. The carrier gas from the chromatographic column also enters the combustion zone through the channel. Using the electric switch 19 serves

oh oh

00

sl j cl

ignition voltage at which the ignition coil 18 is heated to the ignition temperature of the hydrogen-air mixture, and the flame is ignited. The switch 19 is then transferred to another position in which a constant stabilized supply voltage of the detector is supplied to the nozzle 8 of the burner b and the ignition coil 18, and between the burner 6 serving as a potential electrode, the ignition coil 18 also playing the role of a potential electrode, and the collector electrode 14 generates an electric field. In a hydrogen flame, an ionized medium is formed. The ions are moved between the electrodes and neutralized by the electrodes. However, part of the ions due to the forces of internal friction and the good gas dynamics of the detector slips past the collector electrode to the detector output. The ignition coil 18, located on the side of the collector electrode, being under the potential of the nozzle, creates a field inhibiting the passage of ions, and directs them to the collector electrode 14. Thus.

Indicators

The flow rate of carrier gas (nitrogen), /

Hydrogen consumption, cm / min

Air consumption, cm / min

Temperature, ° С

The temperature of the thermal column, ° C

Metal column: length, cm diameter, mm

Sorbent chromatone silanized ZE 30,% impregnation

The control substance is a mixture of hexane but no:

concentration, mg / ml, dose, µl

Power supply voltage, V Background current, no more, A Level of fluctuating noise, A Threshold value of sensitivity, mg / s: tape speed of a KSP-4 pontetiometer. mm / h

the negative effect of good gas dynamics, which allows ions to slip to the detector output, is compensated for by the collection efficiency of ions on the collector electrode using an ignition coil.

The test results are shown in the table.

Formulas a and 3 gains A flame ionization detector, comprising a housing with channels for supplying and discharging gases, a burner serving as a potential electrode, a collector electrode made in the form of a truncated cone and facing the burner with a large base, a burner ignition element, as well as power sources electrodes and an ignition element and an electrical switch, alternately connecting the burner and the ignition element with the corresponding power sources, characterized in that, in order to increase the sensitivity and expansion of the line The dynamic range of the detector, the ignition element is installed along the axis of the collector electrode from the side of the smaller base of the cone.

Values for flame ionization detector

66

46

500

200

90

50 3

2.8 0.5

300

2-10

1.0-U

4.0 th

600

Reset

Air

Carry gas /}

2 /

Claims (1)

Claim A flame ionization detector comprising a housing with channels for supplying and discharging gases, a burner serving as a potential electrode, a collector electrode made in the form of a truncated cone and facing the main base to the burner, a burner ignition element, as well as power sources for electrodes and an ignition element and an electric one a switch alternately connecting the burner and the ignition element with the corresponding power sources, characterized in that, in order to increase the sensitivity and expand the linear dynamic range detection zone, the ignition element 25 is mounted on the collector electrode by the axis of the smaller base of the cone. Indicators Values for the flame ionization detector Carrier gas (nitrogen) consumption, cm ³ / min / 66 The consumption of hydrogen, cm ³ / min 46 Air consumption, cm ³ / min 500 Temperature ° C 200 Column thermostat temperature, ° C 90 Metal column: length, cm diameter, mm fifty 3 Sorbent chromaton silanized ZE30,% impregnation 5 The control substance is a mixture of hexane in nonane: concentration, mg / ml, dose, mcl 2,8 0.5 Supply voltage '_300 Background current no more, And 2 10 ^'11 The level of fluctuation interference, A 1.0 -10 ^'14 Sensitivity threshold value, mg / s -So 4,0 ^'10 KSP-4 pontiometer tape speed, mm / h 600 Reset It Compiled by E. Rozhkovskaya Tehred M. Morgenthal Corrector A. Obruchar Order IN 3613 Circulation 497 Subscription 4IIPI of the State Committee for Inventions and Discoveries under the State Committee for Science and Technology of the USSR 113035, Moscow, Zh-35, Raushskaya nab., 4/5 Production and Publishing Combine Patent, Uzhgorod, 101 Gagarin St.