JPS5856831B2 - Tankasisosokuteisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrocarbon measuring device, and particularly to a channel configuration for separating and measuring using a gas chromatogram column.

In measuring air pollution, hydrocarbons in the air are measured, and in this case it is necessary to measure methane and non-methane groups separately.

In conventional equipment, the first column of the gas chromatograph separates methane groups (CH4,02, N2, etc.) and non-methane groups, and the methane groups that are separated and flow out are separated into each component in the second column. A method was adopted in which measurement was performed after separation, backflushing was performed on the first column, and the remaining non-methane groups were measured all at once.

However, according to this method, the times at which the peaks of methane and non-methane groups appear are almost the same, so the purpose of the separation measurement of this device cannot be achieved.

In order to solve these drawbacks, we developed a channel configuration in which only a specific component that is to be delayed is stored in a dummy column, separated from the channel for the desired delay time, and then reintroduced into the channel after the elapse of that time. ``Latest gas chromatography basics and applications - 1 - Basic edition'' edited by 1 other person
0.3.30) General Bookstore P, see Figure 110 (l-3))
It is also possible to employ this in the second column flow path, but for this purpose, a switching cock must be provided together with the dummy column, which complicates the flow path configuration and makes its operation complicated.

Additionally, in general, when the peaks of multiple components overlap in a gas chromatograph flow path, a resistor is often inserted into the flow path to delay the outflow of one of the components. When applied for this purpose, a pressure drop occurs across the resistor only in the second column flow path where the resistor is inserted, and as a result, the pressure drop is set to an optimal value taking into account the effect on column efficiency, retention time, and detector sensitivity. This causes a change in the carrier gas flow rate (flow velocity) and pressure, so the conditions must be set again.If a configuration is adopted in which a simple resistance like this is inserted into the flow path to delay a specific component, This will involve extremely troublesome operations.

In view of the above, this invention can avoid the overlapping of peaks without the above-mentioned disadvantages by interposing an aerodynamic ram with almost no resistance in series on the upstream side of the column in the second column flow path. , to provide a hydrocarbon measuring device that makes it possible to detect non-methane groups first.

Note that by detecting the non-methane group first, the peak becomes sharper and the quantitative accuracy improves.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be explained below with reference to embodiments of the drawings.

FIG. 1 shows an example of the flow path configuration of the present invention.
is a switching valve, the solid line shows the flow path for sampling @ (or after backflushing), and the dotted line shows the flow path for the period after sampling until backlash.

Reference numeral 1 denotes a sample collection port, and the sample sucked by the pump P fills the sample pipe (solid line flow path of valve V, which will be described later).

C is a carrier gas flow path (inflow port), and the carrier gas is branched at point 2, and the two flow path systems are configured to be switchably connected by a valve V, namely: (4) Carrier gas flow path C ~ metering pipe - Column flow path of the first gas chromatograph having the first column (pre-column) PC - Empty column E - Second column (main column) M
a first flow path system (dotted line flow path of valve V) connected in order from the column flow path of the second gas chromatograph having C to the detector; and (B) the column flow path C to the first Flow path system (4)
a first column flow path in a flow direction opposite to the flow direction in ~
A second flow path system of two channels, in which flow path resistance R1 - detector, and carrier gas flow path C - flow path resistance R2 - empty column E - second column flow path - detector are connected in order, respectively. , flows through both flow path systems.

With the above flow path configuration, the sample (for example, air) sampled into the metering pipe by operating the valve V is transferred to the carrier gas by switching from the solid line of the valve V to the dotted line flow path, that is, the first flow path system A. is sent to the first column (pre-column) PC, where it is roughly divided into methane groups such as CH4,02, N2, etc. and non-methane groups.

Then, the methane group separated in this pre-column PC flows out of this pre-column PC and flows into the second column flow path through the switching valve V, and then passes through the valve V into the solid line flow path, that is, the second flow path system B. When switched, the non-methane groups remaining in the pre-column PC are backflushed by the backflow of carrier gas, reach the detector via resistor R1, and are detected.

On the other hand, after passing through the aerodynamic ram E, the methane group is separated into its respective components in the second column (main column) MC, and then detected by a detector.

As a result, as shown in the chromatogram in Figure 2, the methane (CH4) peak reaches the detector after the non-methane peak has completely eluted, so methane and non-methane are completely separated. The purpose of this measuring device is to measure each of the two.

In this example device, the size of the aerodynamic ram is 3 mrL internal diameter and 10 m length, in which case the non-methane group elutes between 0.5 and 5.5 minutes after sampling;
Methane eluted between 7 and 8 minutes.

(In addition, when the aerodynamic ram is not inserted, methane is 1 to 1
．． It eluted in 5 minutes and almost completely overlapped with the non-methane peak.

) Since this aerodynamic ram has almost no resistance, its insertion does not disturb conditions such as the flow rate (flow rate) and pressure of the carrier gas.

In addition, in general, in gas chromatographs, creating dead spaces in the flow path is avoided because it leads to broadening of peaks due to diffusion and poor peak separation, and providing an aerodynamic ram as in this invention is Although this goes against common sense, by inserting an aerodynamic ram upstream of the main column, problems such as peak broadening do not occur.

As is clear from the above, the present invention has a flow path configuration in which only an extremely simple aerodynamic ram is inserted, which does not require filling with filler, thereby delaying the elution time of methane without requiring the complicated operation of a switching cock. It is possible to set a time difference between the methane elution time and the methane elution time, and the elution time of methane can be arbitrarily adjusted simply by adjusting the dimensions of the aerodynamic ram without affecting the set measurement conditions.

Note that by detecting non-methane first, the peak becomes sharper, which has the effect of improving quantitative accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an embodiment of a channel configuration of the present invention, and FIG. 2 is a diagram showing an example of a chromatogram. ■・・・Valve, L・・・Measuring tube, P...
...Pump, C...Carrier gas, D...
...Detector, PC...1st column (pre-column), MC...2nd column (main column)
, E...Aerodynamic ram, R1, R2...Flow path resistance.

Claims (1)

[Scope of Claims] 1(A) A first flow formed by sequentially connecting a carrier gas flow path, a metering tube, a column flow path of a first gas chromatograph, a column flow path of a second gas chromatograph, and a detector. and (B) carrier gas flow path to the first flow path system (4).
The first column flow path to the detector, and the carrier gas flow path to the second column flow path to the detector are connected in order, respectively, in a flow direction opposite to the flow direction in The flow path system (2) is configured to be connected to be switchable by a switching valve, and the sample sampled in the measuring tube in the first flow path system (4) is introduced into the first column flow path. The methane group is separated into a methane group and a non-methane group, and the methane group passes through the switching valve and flows into the second column flow path, and then is switched to the second flow path system (B), and the methane group is separated into the second column flow path. The apparatus further separates each component in the column flow path and measures it, and also measures the non-methane group all at once by backflushing the first column flow path, the apparatus comprising: a column upstream of the column in the second column flow path; A hydrocarbon measuring device characterized by an aerodynamic ram connected in series on the side.