Title of Invention

A DEVICE USEFUL FOR IN SITU SEPARATION OF VOLATILE METAL HYDRIDE FROM LIQUID SAMPLE.

Abstract The invention relates to the development of a device for in-situ gas-liquid separation for wider applicability in low level estimation of metal hydrides by instrumental techniques. It has also special application for continuously feeding the separated gas components of liquid gas mixtures into bench level bioreactor or chemical reaction chamber for further investigations. The design of the device has been from standard glass materials for maintaining the transparency for observing the in-situ reactions. The device has been optimized and tested for estimation of metal hydrides in environmental samples at ppb levels.
Full Text The present invention relates to the development of a device for in-situ gas-liquid separation.
The device of this invention particularly relates to a device for in-situ gas-liquid separation useful for application in feeding the volatile hydrides of metals like arsenic, selenium to instruments like atomic absorption spectrophotometer, bioreactors or any special in-situ reactor systems.
The device is useful for gas-liquid seperation and generation of covalent hydrides at very low levels (ppb) and subsequent estimation using atomic absorption spectrophotometer. It may also be useful for laboratory applications for feeding the separated gas into chemical/biological reactors for specific studies.
For rapid determination of concentration of metal in environmental samples, instrumental technique of Atomic Absorption Spectrophotometer is very much useful. In this, the aqueous sample is aspirated into the air-acetylene-flame and the signal response is noted. This is proportional to the concentration of metal ions. However, certain metal forming cohydrides are not readily amenable to direct determination by flame technique. The drawback of direct determination with the flame technique is that the covalent hydrides are highly volatile and by the normal process of aspiration does not reach the flame immediately. About 20-30% only reach the flame. Hence, development of a device to generate quick hydride and transfer it as fast as possible to the flame has been the purpose of designing a gas liquid separator assembly. It was essential to consider the fact that the chemical reactions take place in-situ and the products are automatically fed to the

flame. This invention would lead to determination of metals in ppb range so as to compare with the low level standard laid down by the regulatory authority. The gas-liquid separator will also help in continuous measurement of metal ions.
There is no such device has been reported in the literature. The device of the present invention developed by us is new and novel.
The main object of the present invention is to develop a simple gas-liquid separation device out of glass and use it with Atomic Absorption Spectrophotometer in atomic mode for determining low levels of covalent metal hydrides in environmental samples.
Another object of the present invention is that it would replace the costly hydride generating assembly which is being imported.
Still another object of the present invention is to design optimised device for gas liquid separation the separator for low level detection of volatile metal hydrides.
In the drawings accompanying this specification figure 1 represents gas-liquid separator and figure 2 represents main parts including device for use with instrument like Atomic Absorption Spectrophotometer.
Figure 1 of the accompanying drawings represents the Gas-Liquid Separator consisting of inlet for purge gas (1), inlet for sample and hydride (2), outlet for gas hydride(3), upper part(4), lower part (5), U-tube or liquid drop collector(6), and liquid outlet (7).

Figure 2 of the accompanying drawings represents the device for use with instrument like Atomic Absorption Spectrophotometer. It consists of Gas-Liquid Separator (8), T-Controller{9) for automatic mixing of the reagents for gaseous hydride generation, and Flow meter (10).
The basic steps involved in the design of the device was to make it out of a glass for transparency and easy handling in the laboratory for wider applications. Another important aspect of the invention was that it should work in a continuous mode so that the reagents are automatically reacted and pumped into the glass device for separation of gaseous and liquid components and subsequently transporting the gaseous component to systems like Atomic Absorption Spectrophotometer.
Accordingly, the present invention provides a device for in-situ gas-liquid separation which comprises a non-corrosive, transparent and nonflammable gas-liquid separator(figure 1) consisting of two parts, namely the upper part(4) & lower part(5), the upper part(4) is provided with inlet(1) for feeding purge gas which extends upto upper end of the said lower part(5), another inlet(2) for feeding hydride and liquid mixture which extends to the bottom of the said lower part(5), one outlet(3) for gas hydride, the said lower part(5) having U-tube monometer(6) being connected to its conical bottom, an outlet(7) for draining liquid being connected to the said U tube(6) at an acute angle and at the level of conical bottom of the said lower part(5), the said two parts(4&5)attached with each other by a standard joint of least 24/29.
In an embodiment of the present invention the device is easy to fabricate out of standard glass material like borosil, coming or pyrex.

in another embodiment of the present invention is that an efficient separation of gaseous component from the liquid phase takes pface in a continuous mode and when applied to estimation of gaseous hydride with Atomic Absorption Spectrophotometer it lowers down the detection limit to ppb for covalent hydrides of metals like arsenic, selenium etc.
!n yet another embodiment of the present invention the device can be used for in-situ gas seperation from liquid -gas mixtures and feeding it in bioreactors or chemical reactors for specific experimental studies.
In still another embodiment of the present invention the device could replace costly accessories being imported with the analytical instruments like Atomic Absorption Spectrophotometer.
The application of the device shown in Figure 2, viz. Gas liquid separator assembly (8), the T-connector (9), the flow meter (10) and AAS Burner(11) is in the following manner^ the gas- liquid separator contains two parts(4&5) attached with each other with at least standard joints of the type 24/29.The upper part houses inlet for purge gas(1) like Nitrogen, inlet for gases and sample{2), outlet for the gas(3) for feeding to the flame attachment(11A). The lower part(5) contains the separator with a U tube(6) for collecting the liquid droplets and an inclined side tube(7) for draining the liquid. The T- controller{9) allows efficient mixing of the reagents to generate the gaseous hydride from sodium tetrahydroborate in case of arsenic estimation. The mixture of gaseous hydride and the liquid sample from 9B then flows through the inlet(2) into the gas liquid separator where the gaseous portion is plunged from the liquid phase with nitrogen. The mixture of

gaseous hydrides and nitr )gen is introduced from outlat(3) into the AAS flame burner(11) through a quar z tube(11 A) placed above the burner.
For the efficient operation of the device of the present invention, a multi-channel peristaltic pump is used to transfer the sample into a T -Controller (9) wherein, the reaction takes place and the gaseous components along with the liquid are fed into the gas liquid separator(8) assembly. A glassware to separate the gaseous and liquid portions of the samples, an inlet for carrier gas to drive the gaseous components into the flame of AAS or a reaction chamber or a bioreactor. Care was necessary in designing the separator to avoid accumulation of reaction products in the device and immediate draining of the liquid products so as to avoid any interference in the subsequent continuous operation. In the device shown in Figurel the purge gas (Nitrogen)that enters through the inlet (1). The gaseous hydrides with the liquid samples enters through the inlet (2). The purge gas carries the hydride through (3) into the quartz tube placed over the flame and detected. The lower portion of the device was designed in such a way that the liquid drops fall into (6) and drain through outlet (7). The curvature (6) is important so as to drive the vapor into the instrument system like flame AAS immediately to increase the sensitivity of the element detection in the ppb range.
For determination of covalent hydride in aqueous samples, the three connections of the T - controller are connected by connector 9B to the inlet 2 of gas liquid separator, connector 9C to the rotameter for feeding samples and the connector 9A to reagent feeding assembly. The purge gas flow rate is adjusted by the flow meter(10). The outlet from the separator(3) is suitably

connected through a quartz tube(11A) to the air- acetylene flame burner (11) of instrument like MS for metal hydride estimation. The reagents and the sample are thus mixed in a T- controller and then are pumped into the separator(8). The gaseous hydrides flow out into the flame. A signal proportional to the concentration of metal ions is obtained and recorded. Thus, the conditions for reaction and detection are optimized. The concentration is recorded directly on the Personal Computer attached to Atomic Absorption Spectrophotometer.
The main advantage of the present invention are :
• The present invention relates to the development of a device for in-situ gas
liquid separation and can be used for determination of covalent metal
hydride with AAS. Covalent hydrides are a series of compounds whose
elements are of C, N, 0 groups where the number of valency electron is
equal to or greater than the number of orbitals. These elements include
As, Al, B, Bi, Ge, P, Pb, Se, Sb, Si, Sn, Te and Ti. Of these 13 elements,
8 have been induced to form covalent hydride in sufficient amounts to be
of practical analytical use; these are: As, Bi, Ge, Pb, Se, Sb, Sn and Te.
As these covalent hydrides are highly volatile they are difficult to detect at
low concentrations by directly aspirating the sample into the flame of AAS.
The device becomes advantageous in such application.
• The device is easy to fabricate in any glass workshop.
• The device can be used for in-situ gas generation besides gas-liquid
separation at bench level and also for use of separated gas for studying
reactions in bio-reactors.

• The reagentts are nixed automatically in the separator, thereby manual
chemical exposure is avoided.
• The easy adaptability of the device for continuous sample analysis has
advantages over the other conventional techniques.
• The changeover from conventional mode of flame MS to gas liquid
separator mode takes only five minutes.



We claim:
1. A devise for in-situ gas-liquid separation which comprises a non-
corrosive, transparent and non-flammable gas-liquid separator(figure 1)
consisting of two parts, namely the upper part(4) & lower part(5), the
upper part(4) is provided with inlet(1) for feeding purge gas which
extends upto upper end of the said lower part(5), another inlet(2) for
feeding hydride and liquid mixture which extends to the bottom of the
said lower part(5), one outlet(3) for gas hydride, the said lower part(5)
having U-tube monometer(6) being connected to its conical bottom, an
outlet(7) for draining liquid being connected to the said U tube(6) at an
acute angle and at the level of conical bottom of the said lower part(5),
the said two parts(4&5)attached with each other by a standard joint of
least 24/20.
2. A device as claimed in Claim 1, wherein the gas-liquid separator is
made up of Borosil glass, Pyrex glass or Coming glass.
3. A device for in-situ gas-liquid separation substantially as herein
described with reference to the drawings accompanying this
specification.

Documents:

255-del-2000-abstract.pdf

255-del-2000-claims.pdf

255-del-2000-correspondence-others.pdf

255-del-2000-correspondence-po.pdf

255-del-2000-description (complete).pdf

255-del-2000-drawings.pdf

255-del-2000-form-1.pdf

255-del-2000-form-19.pdf

255-del-2000-form-2.pdf

255-del-2000-form-3.pdf


Patent Number 212997
Indian Patent Application Number 255/DEL/2000
PG Journal Number 01/2008
Publication Date 04-Jan-2008
Grant Date 19-Dec-2007
Date of Filing 16-Mar-2000
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG NEW DELHI 110 001, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 PRADIP LAXMAN MUTHAL NEERI, NEHRU MARG, NAGPUR - 440020 (MS) INDIA.
2 SURESH MAROTRAO DHOPTE NEERI, NEHRU MARG, NAGPUR - 440020 (MS) INDIA.
3 PRAKASH SHANKARRAO KSHIRSAGAR NEERI, NEHRU MARG, NAGPUR - 440020 (MS) INDIA.
4 GIRISH HIMATLAL PANDYA NEERI, NEHRU MARG, NAGPUR - 440020 (MS) INDIA.
5 VIVEK KESHAO KONDAWAR NEERI, NEHRU MARG, NAGPUR - 440020 (MS) INDIA.
PCT International Classification Number B01D 19/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA