SU665542A1

SU665542A1 - Ionization detector for gas chromatography

Info

Publication number: SU665542A1
Application number: SU772503196A
Authority: SU
Inventors: Я.А. Микк; В.А. Иоонсон
Original assignee: Специальное Конструкторское Бюро Ан Эстонской Сср
Priority date: 1977-07-01
Filing date: 1977-07-01
Publication date: 1980-02-25

Description

(54) ИОНИЗАЦИОННЫЙ ДЕТЕКТОР ДЛЯ ГАЗОВОЙ . . ХРОМАТОГРАФИИ(54) IONIZATION DETECTOR FOR GAS. . CHROMATOGRAPHY

Изобретение относитс к области газовой хроматографии и может быть применено при анализе электроотриадательных веществ при помощи.ионизационного детектора.The invention relates to the field of gas chromatography and can be applied in the analysis of electroplating substances using an ionization detector.

Известна измерительна схема электронно-захватного Детектора дл газовой хроматографии, содержаща из,меритёльную камеру детектора, источник напр жени , измерительный усилитель и включенный между источником напр жени и измерительной камерой детектора резистор величиной сопротивлени пор дка 5-10 ом Ц .A known measurement circuit of an electron capture detector for gas chromatography, comprising, from, a measuring chamber of the detector, a voltage source, a measuring amplifier, and a resistor connected between a voltage source and a measuring chamber of the detector, has a resistance value of about 5-10 ohm.

Однако большое сопротивление резистора , который включен между источником напр жени ,и измери1 ельной Камерой детектора, вызывает повышен-ный уровень флюктуационных щумов в выходном сигнале детектора, что в свою очередь ухудшает уровень пороговой чувствительности детектора. Кроме того, схема не позвол ет поддерживать величину электрического .тока через измерительную камеру по- . сто нной в широких пределах изменений концентрации исследуемых веществ, что вызывает заметаую нелинейность зависимости сигнала детектора от измер емой концентра.цйй.However, the high resistance of the resistor, which is connected between the voltage source and the measuring chamber of the detector, causes an increased level of fluctuation noise in the output signal of the detector, which in turn worsens the level of the threshold sensitivity of the detector. In addition, the circuit does not allow maintaining the amount of electric current through the measuring chamber. over a wide range of changes in the concentration of the test substances, which causes a noticeable non-linearity in the dependence of the detector signal on the measured concentration.

Наиболее близким к изобретению по технической сущйости и достигаемому, результату вл етс ионизационный детектор дл газовой хром ографии, содержащий ионизационную камеру,вход которой Соединен через токозадающее звено с источником напр жени ,а так0 же через усилитель с регистраторс л. В качестве задающего звена исполь- . .зована ионизационна камера 12 .The closest to the invention in technical essence and the achieved result is an ionization detector for gas chromography, containing an ionization chamber, the input of which is connected through a current-generating link with a voltage source, as well as through an amplifier with a recorder l. As a setting link used. The ionization chamber 12 is called.

Однако ионизационна камера, питаема от высоковольтного источника However, the ionization chamber is powered by a high voltage source.

5 напр жени , создает дополнительный уровень флюктуациЬнных шумов в выходном сигнале детектора, что также . вызывает ухудшение уровн пороговой чувствительности детектора. Кро- 5 voltage, creates an additional level of fluctuating noise in the output signal of the detector, which also. causes a deterioration in the threshold sensitivity of the detector. Kro

Q ме того, стоимость ионизационной камеры примерно равна стоимости .измерительной камеры детектора.In addition, the cost of the ionization chamber is approximately equal to the cost of the detector's measuring chamber.

5five

Цель изобретени - расширение диапазона измерени детектора.The purpose of the invention is to expand the measuring range of the detector.

Claims

The goal is achieved by the fact that the amplifier and the ionization chamber are connected in parallel to each other between the current supply link and the recorder. The drawing shows the measuring circuit of the electron-capture detector The circuit contains a source 1 of a constant or pulsed voltage, a current-generating link (for example, a resistor) 2, a measuring amplifier 3, an ionization chamber 4, and a recording device 5. The measuring circuit operates as follows. The current, the magnitude of which is determined by the voltage of the voltage source 1 and the resistance of the current-generating resistor 2, is derived from the current through the ionization chamber 4; the difference of currents is the input signal of the inverting input of the measuring amplifier 3. An operational amplifier with a high input-resistance is used as the measuring amplifier. Since the ionization chamber is connected to the negative feedback circuit of the operational amplifier, the magnitude and stability of the current through the ionization chamber of the detector is determined It is provided only by the relevant parameters of the current-generating link (voltage source and current-resistor) and does not depend on the voltage on the measuring chamber re detector. The advantage of this scheme is a significantly lower level of fluctuation noise in the output signal of the detector due to the relatively low possible resistance of the capacitive resistor (about 10 ohms), which improves the threshold sensitivity of the detector and thereby expands the measuring range . An advantage of the invention is that a voltage source of about 1 V can be used as a source, a voltage source, and a resistor as a current supply link, therefore there is no need to use a high-voltage source for setting the current through the measuring chamber ionization chamber, which greatly simplifies the design. Claims Ionization Detector For gas chromatography, comprising an ionization chamber, the input of which is connected through a current supply link to a voltage source, and the output is connected to an amplifier that is connected to a recorder, characterized in that, in order to extend the measuring range, the ionization chamber and the amplifier is connected in parallel to each other between the current supply link and the recorder. Sources of information taken into account during the examination 1. USSR author's certificate No. 317971, cl. Q 01 N 27/62, 1969.

2. Author's certificate of the USSR 329466, class, G 01 N27/62, 1970.