DE102004026379B4 - Scattered light detector - Google Patents

Abstract

Evaporative light scattering detector with an evaporation section (1) of a round in cross section or angular channel (2), which is formed by two plates (3) with millings (4) is formed, with a sharp-edged or round baffle (5) is set up.

Description

Territory of invention

The The invention relates to an evaporative scattered light detector with a Evaporation zone and a method for operating such Evaporative light scattering detector.

State of the art and Background of the invention.

From the literature US 4,958,529 , WO 02/18939 A1, US 2003/0086092 A1, US 6,229,605 . US 6,122,055 and US 2001/001575 A1, various variants of evaporative scattered light detectors are known. In at least some of these detectors, the atomizing gas and / or the eluent stream is preheated.

Evaporative light scattering detectors be in liquid chromatography used for the detection of substances that are difficult to vaporize. The eluent stream from a column is with a nebulizer sprayed and the fine drops are evaporated in a heated tube. If the Drops containing a heavy vaporizable portion forms a fog that is detected by the scattered light effect.

The Improvement of atomization is the task. The normal atomizers work with one nozzle and one fast gas flow, the nozzle wrapped and the drops from the nozzle interrupted. The atomizing gas flow usually has room temperature.

Solution of the task

to solution The object of the invention teaches the subjects of the claims.

The atomizing is preheated. The preheating can through heat exchange on the heating tube (evaporation tube) carried on the temperature at the evaporation tube or by a separate heater to a temperature between room temperature and temperatures higher as in the evaporation tube. In the separate heater, the temperature can be unregulated or regulated.

Of the Eluent stream is preheated. The preheating should by a dead volume low separate heater between room temperature and up to a maximum of 200 ° C heated become.

Of the Eluent stream is passed through a high-pressure pump in liquid chromatography delivered. The atomization takes place on a nozzle plate very small thickness with a hole diameter between 10 and 100 microns. By the relaxation tears the eluent stream in evenly small droplets. The eluent stream and / or the Zerstäubergas can also be preheated.

The Evaporation section consists of a round or square channel, which is formed by two plates with millings that a preferably sharp-edged, but also round baffle wall arises, which intercepts the larger droplets. The droplet run through a provided with a siphon drain.

• • Der Zerstäubungsgasstrom wird vorgeheizt und bringt dadurch eine schnellere Verdampfung. Die entstehenden Tröpfchen sind durch Verringerung der Viskosität kleiner und in der Größe gleichmäßiger.
• • Durch Vorheizung des Eluentenstromes wird auch eine Verbesserung der Zerstäubung erreicht.

The following improvements are achieved:

• • The atomizing gas stream is preheated, resulting in faster evaporation. The resulting droplets are smaller by reducing the viscosity and more uniform in size.
• • Preheating the eluent stream also improves atomization.

There the eluent flow through a high-pressure pump in liquid chromatography can be supplied, the atomization also on a nozzle plate very small thickness e.g. 0.1 mm with a hole diameter between 10 and 100 μm respectively. At this time, the eluent flow of e.g. 50 bar at atmospheric pressure on a running track of e.g. 0.1 mm. This causes a tearing of the stream in equally small droplet from about 20 u ⌀. The eluent stream and / or the Zerstäubergas can also be preheated

These sputtering was previously for Evaporative scattered light detectors not yet applied.

A another known method to improve the quality of the atomized eluent, is the biggest droplets through to catch a baffle plate.

The single figure shows an embodiment. According to the invention, the heated evaporation tube is replaced by 2 metal plates ( 3 ) are inserted in the evaporation channels so that a baffle ( 5 ) arises. At the baffle wall ( 5 ) larger droplets would be deposited. The system is slightly inclined, so that the baffles ( 5 ) collecting droplets through the process ( 8th ) can flow. The evaporation tube is usually a tempered straight tube or a coiled one Pipe to increase the length of the pipe.

According to the invention, the evaporation path ( 1 ) from a round or square channel ( 2 ) so through two plates ( 3 ) with millings ( 4 ) is formed, that a preferably sharp-edged, but also round baffle ( 5 ) arises.

The system is slightly inclined, so that the baffles ( 5 ) collecting droplets through the process ( 8th ) can flow.

Claims (7)

Evaporative scattered light detector with an evaporation section ( 1 ) of a round or rectangular channel ( 2 ), which passes through two plates ( 3 ) with millings ( 4 ), wherein a sharp-edged or round baffle wall ( 5 ) is set up. An evaporative scattered light detector according to claim 1, wherein in one of the plates ( 1 ) a preheating channel ( 6 ) is arranged for nebulizer gas. Evaporative scattered light detector according to claim 1 or 2, wherein one with a siphon ( 7 ) (process) 8th ) is arranged for collecting droplets. Method for operating an evaporative scattered light detector according to one of claims 1 to 3, wherein the plates ( 3 ) heated and so that the preheating channel ( 6 ) is pre-heated by sputtering gas flowing through. The method of claim 4, wherein an eluent stream preheated becomes. Method according to claim 4, wherein the preheating of the Eluent stream by means of a dead volume poor separate heater to a temperature between room temperature and 200 ° C. A method according to any one of claims 4 to 6, wherein the eluent stream delivered by a high pressure pump in liquid chromatography is, and where the atomization on a nozzle plate with a hole diameter between 10 and 100 microns.