FR2549228A1 - PROCESS FOR THE PRODUCTION OF FLEXIBLE SILICEOUS CHROMATOGRAPHIC CAPILLARY COLUMNS AND APPARATUS FOR IMPLEMENTING THE SAME - Google Patents

Abstract

A SILICEOUS GLASS TUBE IS LESSIVED IN HYDROFLUORIC ACID OR IN NITRIC ACID, RE-POLISHED IN OXYHIDRIAL FLAME AND FIRE AT THE TEMPERATURE OF 1800 TO 2100C IN A CAPILLARY OF AN EXACT DIAMETER, USING AN ARMOR METER. WITHOUT TOUCHING THE INSIDE DIAMETER, CONNECTED TO A TUBE ADVANCEMENT REGULATOR IN THE OVEN, WHILE MAINTAINING AN INERT ATMOSPHERE INSIDE THE TUBE AND THE CAPILLARY. A LAYER OF POLYIMIDIC OR POLYESTERIMIDIC LACQUER IS APPLIED ON THE OUTER SIDE OF THE HAIR LACQUER USING A SOFT SILICONIC RUBBER NOZZLE AND THIS LACQUER IS HARDENED USING A GRADUALLY INCREASED TEMPERATURE. THE APPLICATION OF STATIONARY PHASE ON THE INNER SIDE OF THE CAPILLARY IS CARRIED OUT BY WINDING THE CAPILLARY 5 IN THE THERMOSTAT 1 HEATED AT A TEMPERATURE OF 150 TO 250C, USING A STATIONARY PHASE SOLUTION.

Description

Process for the production of chromatographic capillary columns

  flexible silicates and apparatus for its implementation.

  The present invention relates to a method for

  the production of flexible siliceous chromatographic capillary columns having an exact inside diameter.

  The invention also relates to an apparatus for the

implementation of this method.

  In gas chromatography glass capillary columns are increasingly used because of their high efficiency of division, which is important especially in case of division of very complex mixtures of compounds. One of the important prerequisites during the preparation of the columns. , high-efficiency, is obtaining the surface inertia of the inner wall of the capillary tube, on which is applied the stationary phase The surfactant sites on the surface of the capillary, whose existence is attributed to the The presence of silanol groups and the presence of metal oxides in the glass cause, under the influence of a higher adsorption of analyzed substances, a deformation of the chromatographic zones, especially during the analysis of substances which are very This makes it difficult to decipher a chromatogram and often distorts the results of the analysis. to perform in the case of glass columns a deactivation of the inner surface, very demanding from the point of view of time, and this before the loading even by the stationary phase One of the main disadvantages of glass columns is their low flexibility which causes often their cracking at

course of manipulation.

  Because of the aforementioned disadvantages of the glass columns 35, in recent times a stronger attention is

  lent to the development of siliceous capillary columns.

  The siliceous capillary columns described in J High Resolut Chromatogr Chromatogr Commun 2 (1979) 2 and in Amer Lab (1979) 61 have an advantage because they are flexible and have a very small amount of metal oxides per unit area. compared to glass capillary columns They also contain a smaller amount of silanol groups relative to glass columns and for this reason the process of deactivating the inner surface by the processes

known is easier.

  It is known to perform the deactivation of the inner surface of siliceous capillaries for example by polyethyleneoxide, dimethyldichlorsilane, trimethylchlorislane and hexamethyldisilazane Also known are the processes for coating the outer surface of siliceous capillary columns with silicone rubber a polyimide, silicon nitride,

  where appropriate by some of their compounds.

  Also known is the drawing of siliceous capillary columns on a modified stamping die for the capillary tubes (see HD Desty et al., Anal Chem 32,302,1960), during which the siliceous tube is heated, either by the oxyhydric flame, The oxypropane flame is also known for drawing a siliceous capillary tube heated with a resistance electroform or with a high frequency induction furnace (see Jpn Kokai). Tokkyo Koho

JP 82.03,723).

  The disadvantages of known processes and equipment are mainly the fact that it is not always possible to observe during drawing

  of the capillary tube an exact inner diameter, that only the capillary tubes of quality and having very regular shapes can be used and that in the course of

  of the capillary column, silanol groups may arise on the inner wall of the capillary

  undesirable because of contact with the humidity of the air.

  Other disadvantages are also, on the one hand, the presence of the accompanying impurities (especially metal oxides) on the inner wall of the capillary tube, which adversely affect the properties of the chromatographic column, and on the other hand On the other hand, the difficulties related to the application process of the outer polymeric layer, having a uniform thickness. Also the application of the stationary phase on the inner surface of the capillary column is relatively complicated and very demanding from the point of view of the time (by example during the use of said static method, the anchoring of the stationary phase lasts

even a few days).

  The above disadvantages are eliminated in accordance with the present invention by a process for the production of flexible siliceous chromatographic capillary columns having an exact inside diameter.

  and apparatus for carrying out this method.

  The invention is based on the fact that the speed of advance of the heated tube at the temperature of 1800 to 2100 C, more preferably at the temperature of 1850 to 1950 C, is controlled according to the data provided by the shield meter, without touching the inner diameter of the capillary; then on the outer wall of the capillary is applied polyesterimide lacquer or polyesterimide lacquer with subsequent curing at temperatures of 280 to 350 C, more preferably 300 to 320 C, and finally on the inner wall of the capillary is applied a

layer of the stationary phase.

  Subsequently the surface of the siliceous tube is subjected, before the procedure of the capillary stretching at least two repolissages, in oxyhydric flame, while during the first passage of the siliceous tube the temperature of the oxyhydric flame is 1800 at 1900 ° C, more preferably from 1850 to 1880 ° C, the rotational speed of the tube is from 40 to 60 rpm, more preferably from 50 to 55 rpm and the speed of advancement of the oxyhydrogen flame burner is 30 to 50 mm / minute, more preferably 40 to 45 mm / minute, and during subsequent passage of the siliceous tube at the same temperature and at the speed of rotation, the speed of the advance of the burner is 120 to 160 mm / minute, more preferably from 140 to 160 mm / minute. Before the repolishing procedure, the siliceous tube is washed for 5 to 10 minutes in hydrofluoric acid or in a solution of hydrofluoric acid and nitric acid. , with subsequent wash in the distilled water According to the following method, during the stretching of the capillary inside the tube and the pulled capillary, the protective atmosphere is maintained by passing dry gases, for example oxygen, chlorine, Helium, argon, and more preferably argon. The curing of the polyimide lacquer or the polyesterimide lacquer is carried out at a temperature which increases continuously from 50 to 350 ° C. one at 10 C / minute, more preferably 3

at 6 C / minute.

  Finally, according to the last feature, the application of the stationary phase layer on the inner surface of the capillary is effected by winding the capillary, filled with the stationary phase solution, with an open end, in a heated thermostat. at a temperature of 150 to 250 C, more

advantageously from 200 to 220 C.

  The main characteristic of the apparatus for the production of siliceous capillary columns, in accordance with the present invention, consists of the mechanism for the advancement of the siliceous tube, the capillary diameter shielding meter, the device for the application of the top layer of polyimide lacquer

  or polyesterimide, the drying oven and the drawing mechanism, is that the apparatus for the application of the upper polymeric layer is formed by a soft silicone rubber nozzle.

  The apparatus for applying the stationary phase layer is composed of a heated thermostat, in which is placed a rotating coil, actuated by an electromotor with a constant rotation speed and on the outside of the thermostat is fixed again a rotating coil provided with the wound siliceous capillary and from this coil the capillary is rewound in

the thermostat.

  The method and apparatus according to the present invention manifest their effects mainly by the fact that by using the shield meter without touching the inner diameter of the capillary, connected with the control mechanism of the advance of the tube towards the zone 20 oven, the creation of an exact inner diameter of the capillary during any stretching is achieved with

a precision of 4%.

  Also by the process according to the present invention, the formation of silanol groups on the inner wall of the capillary is limited by maintaining the inert atmosphere in the tube and also in the capillary during drawing. the formation of the active centers on the outer surface of the capillary, where the metal oxides and other trace impurities are removed from the surface of the preceding material, i.e., the siliceous glass tube, by leaching with hydrofluoric acid

  or nitric acid or their solution.

  Yet another advantage according to the present invention is the application of a layer

  regular polyimide or polyesterimide having a precise thickness on the outer side of the capillary.

  The increase in the mechanical strength of siliceous capillary columns is achieved by the process according to the present invention, which consists first of all in the fact that the treated siliceous tubes are before the drawing of the capillary subjected to multiple repolissages.

  in oxyhydric flame, and secondly in that the curing of the polymeric outer layer is carried out at a systematically increased temperature.

  Another advantage of the method and apparatus according to the present invention is the considerable shortening of the application time of the stationary phase layer on the inner side of the capillary and the increase of the quality of the

chromatographic columns.

  The method according to the present invention is described in more detail in a few exemplary embodiments and the apparatus for applying the stationary phase according to the present invention is explained in more detail with reference to the drawings.

joints (Figures 1 and 2).

Example 1

  A natural quartz tube containing the following impurities (in ppm): 2 Fe 203, TiO 2, 10A 1203, Na 2 O, 8 K 2 O and OH-, having an outside diameter of 9 mm, a diameter 6 mm inside, a wall thickness of the tube varying by + 8% was fixed in the feed device The end of the tube placed in the clamping chuck of the feed device was packed in a sheet of paper. aluminum to keep the heat free To ensure a balanced heating throughout the perimeter, the tube was carefully centered Then the bottom end of the tube 35 was placed 2 cm below the hot zone of the oven

  with graphite resistance and the temperature of the hot zone was raised to 21000 CA this temperature occurred the effect of the dripping of the end of the tube and the capillary was pulled by hand up to a length of 3 m .

  Then the oven temperature was lowered to 1900 C and the capillary extended to the tension rollers. The oven temperature was then increased to 21000 C and the capillary was placed between the rotating tension rollers and pulled at a speed of 6 m / min. Then the drawing speed and the tube advance were successively increased while lowering the temperature of the hot zone to 1900 ° C, when the inner diameter of the capillary reached 200 μm. The inner diameter of the capillary was measured during drawing by the diameter shielding meter and using the speed regulator of the advance of the tube towards the hot zone of the graphitic furnace, the internal diameter of the capillary was maintained with an accuracy of + 4% at the exit of the graphitic furnace was applied, on the capil20 drawn silica gel, a layer of polyesterimide lacquer, which was dried by passing the drying oven, heated in its upper part at 400 C and in its bottom part at 250 C hardening of the layer pol Yesterimide was carried out by heating the capillary in the thermostate at the temperature of 330 WC for 3 hours. The ready capillary was filled to a third by the 10% solution of the stationary phase and the solution was pushed by Through the capillary under a pressure of 5 Pa Pa After wetting the entire inner surface of the capillary column with the stationary phase solution, the excess of the solvent was removed from the column by the nitrogen stream and the column was conditioned

  at a temperature of 50 C for one hour.

Example 2

  A synthetic quartz tube was immersed for 10 minutes in a 1: 1: 1 solution of HF: HN03: H20 and then washed with distilled water. The tube was then fixed in the mechanism of advancement and a hole 2 mm in diameter was drilled in this tube just below the fixing in the feed mechanism After placement of the tube precisely in the center of the hot zone of the burnercouronne stretching of the capillary was carried out in flame The capillary was passed through a soft silicone rubber sprinkler nozzle having a diameter of 220 μm. To facilitate the passage before the drawing of the capillary, 0.05 ml of dimethyl polysiloxane oil having a viscosity of 300 mm. c P, was added in the soft nozzle The capillary was pulled while maintaining the constant drawing speed of 7 m / min

  and the constant flame temperature of the 1920 C burner.

  The constant inner diameter of 200 μm of the capillary was preserved using speed control of the advance of the preform towards the hot zone, while using the meter without touching the inside diameter of the capillary. the stretching was kept in the tube and in the capillary drawn an inert atmosphere using argon, which was fed into the tube at a rate of 8 ml / min The solvents of the polyimide layer were evaporated by capillary passage through two drying ovens The first was 25 cm in length, and heated to 400 C and the second was 50 cm in length and heated in its upper part to the temperature of 300 C and in its lower part at the temperature of 3500 C. The thickness of the polyimide lacquer was / um The lacquer hardening was carried out in the thermostat, in which the temperature was gradually increased at a speed of 2 C / min apart From the laboratory temperature to the temperature of 35 140 CA this temperature the column was kept for 30 minutes and then the column was heated at a rate of 4 C / Min to the temperature of 3000 C and this temperature was maintained also for minutes The application of the stationary phase was carried out using the same method as in the case of Example 1.

Example 3

  A natural quartz tube having an outer diameter of 17 mm, an inner diameter of 14 mm and the same composition as mentioned in the case of the example

  1, was immersed for five minutes in concentrated hydrofluoric acid and washed with distilled water.

  The tube was fixed in a glass lathe and at a rotational speed of 50 revolutions / minute inside was kept an overpressure of 5 mm H arc. On the side of the tube was the burner with the flame at a speed of 50 mm / min The tube was thus successively

  heated throughout its length at a temperature of 1800 C.

  Finally the tube was repolished by rapid passage through the burner at a speed of 120 mm / min. In the upper part of the tube was drilled a hole, through which during the stretching was brought the argon in the tube at a rate of 20 ml / min. The tube was then fixed in the advancing device and the passage of the capillary through the soft nozzle with a diameter of 250 μm was carried out as mentioned in the example. During the stretching of the capillary at a constant speed of 6 m / min, the constant temperature of 200 ° C. of the hot zone of the resistance graphitic furnace was maintained. The inner diameter of the capillary of 300 μm was maintained at a constant value in a manner similar to that described in the case of Examples 1 and 2 The polyesterimide lacquer was applied to the outer surface of the capillary using the soft nozzle in the same manner as in Example 2. solvents of the polyeste lacquer were evaporated by passage of the capillary through two furnaces, the first of which was 25 cm long and was heated to 350 C and the second was 50 cm long and was heated in its upper part at room temperature. The polyesterimide layer was cured using the same method as in Example 2. The ready capillary was filled with the 0.6% solution at a temperature of 250 ° C. of the stationary phase in dichloromethane After the sealing of one end, the capillary column was wound on a dural sheet metal coil with a diameter of 15 cm, placed above the thermostat and heated to a temperature of 200 OC The open end of the capillary was brought into the thermostat and fixed on the voice coil, controlled by the En15 electric motor, after which the capillary was rewound at a constant speed of 2.6 mm / sec in the thermostat. After rewinding of the entire capillary column in the thermostat, the sealed end of the capillary was broken and the capillary was flushed with nitrogen for 30 minutes. Thereafter the thermostat heating was stopped and the capillary continued to flow. swept with nitrogen until cooling

  the column at normal temperature.

  FIGS. 1 and 2 show a particular embodiment, seen from two different angles, of the apparatus according to the invention. This apparatus essentially consists of a heated thermostat 1, in which is placed a rotating coil 2, controlled by an electromotor with constant rotation speed 3 and a

  rotating coil 4 for the winding of the capillary sili30 those 5, fixed outside the thermostat 1.

he

Claims (7)

  Process for the production of flexible siliceous chromatographic capillary columns having an exact inside diameter by drawing a siliceous tube, characterized in that the speed of advance of the tube, heated to a temperature of 1800 to 2100 C, more advantageously at a temperature of 1850 to 1950 C, is controlled according to the shield meter data without touching the inner diameter of the capillary, while on the outer side of the capillary is applied a polyimide or polyesterimide lacquer with subsequent hardening at a temperature of 280 at 350 C, more preferably at a temperature of 300 to 350 C, and finally on the inner side of the capillary is applied a layer of stationary phase.   2 Process according to claim 1, characterized in that the surface of the siliceous tube is subjected before drawing in capillary at least two repolissages flame oxyhydrique, while during the first passage of the siliceous tube the temperature of the oxyhydrique flame 20 is maintained at the value of 1800 to 19000 C, more preferably at the temperature of 1850 to 1880 C, the rotation speed at 40 to 60 rpm, more preferably at 50 to 55 rpm, and during the passage next to the siliceous tube, at the same temperature and at the same speed of rotation, the speed of the advance of the burner is kept at a value of 120 to 160 mm / minute, plus   advantageously from 140 to 160 mm / minute.   3 Process according to claim 1 or 2, characterized in that prior to the repolishing of the siliceous tube, washing is carried out in hydrofluoric acid or in a solution of hydrofluoric acid of nitric acid with   subsequent washing in distilled water.   4 Process according to one of claims 1 to   3, characterized in that during drawing of the capillary 35 into the interior of the tube and the capillary drawn an atmosphere of   protective phenomenon due to the passage of dry gases, as   Example of oxygen, chlorine, helium, argon, more preferably argon, is maintained.   Method according to one of claims 1 to   4, characterized in that the curing of the polyimide lacquer or polyesterimide lacquer is carried out at a temperature increased gradually from 50 to 350 C at a rate of 1 to 10 C per minute, more preferably from 3 to 6 C per minute.   6 Process according to one of claims 1 to   characterized in that the application of the stationary phase layer to the inner surface of the capillary is effected by winding the capillary, filled with the stationary phase solution and with a closed end, in the thermostat heated to the heating temperature. 150 to 250 ° C, more preferably 200 to 250 ° C   Apparatus for carrying out the method according to one of claims 1 to 6, comprising a mechanism for advancing the siliceous tube, a tube heating device 20, a diameter shielding meter.   of the capillary, a device for applying a polyimidic or polyesterimidic top layer, a drying oven and an advancing device, characterized in that the device for the application of the diaper   upper polymer is formed of a soft silicone rubber nozzle.   8 Apparatus according to claim 7, characterized in that it consists essentially of a heated thermostat (1), in which is placed a rotating coil (2), controlled by an electromotor constant speed (3) and a revolving coil (4) for   the winding of the siliceous capillary (5), fixed outside the thermostat (1).