Patent Application
20130081484
Gas chromatography (GC) is a well known analytical technique where gas phase mixtures are separated into their individual components and subsequently identified. The technique may be employed to obtain both qualitative and quantitative information about the components of the mixture. Specifically, the separation mechanism employs two different media, one moving (mobile phase) and one unmoving (stationary phase). In GC, the mobile phase is normally hydrogen or helium, which flows across the stationary phase, which is a solid or otherwise immobilized liquid on a solid support on the interior capillary wall.
The sample mixture is introduced into the mobile phase stream and the residence time of each component of the sample in the stationary phase relates to differences in their individual partitioning constants with respect to the two solvent phases.
Samples for GC are usually liquid and must be volatized prior to introduction to the mobile phase gas stream. GC analysis is typically divided into five stages:
In conventional GC instrumentation, step 1 usually involves glass vials or containers, often loaded into an autosampler device. In this fashion the autosampler may contain multiple samples in vials slated for analysis. Steps 2 and 3 are achieved in the sample inlet hardware. Inlet hardware often includes a sample injection syringe and a replaceable sleeve, or liner. Liners are normally operated at elevated temperatures, e.g., over 200′C. This enhances the rate of sample vaporization and reduces adsorption on the inner surface of the liner [1]. Many internal configurations are available for liners, as well as coatings for them [2-12].
In most cases the configuration of the liner serves to enhance the degree of sample volatilization from the point of exit from the syringe needle to the column entrance, and provide gas phase sample homogeneity from components within the liquid mixture having different boiling points. A simple configuration for an inlet liner is a straight cylindrical tube of glass having a consistent inner diameter along the longitudinal path. Other configurations include more complex inner paths intended to increase turbulence, affect the comparatively short residence time the liquid sample is in the liner, or interrupt the liquid stream leaving the syringe needle. These internal configurations include tapers or goosenecks, baffles, funnels, inverted cup elements, spiral regions, points of flow constriction, and drilled holes along the longitudinal path of the liner.
Other elements of liners optionally include small plugs of packing materials such as glass wool [1], Carbofrit™ (Trademark of Restek Corporation) packing material, and more recently inert metal wire bundles [13] which serve as additional surface area sources for heat transfer into the sample and as a physical filter for any solid/nonvolatile contaminants present in the liquid sample.
During the injection process, it is also important to minimize sample/liner and (if applicable) sample/packing material interactions that can result in undesirable chemical reactions, decomposition, or temporary/permanent adsorption of the sample, It is equally important that the liner not contribute contaminants to the analysis, which may result in spurious peaks or an increase in the baseline signal in detection measurements of the components contained in the sample being analyzed.
In cases where liners become contaminated with solid/nonvolatile species it is necessary to replace them from time to time. Liner replacement frequency depends on the type of sample; with ‘dirty’ samples having high concentrations of high boiling point components or large amounts of nonvolatile particulate matrix shortening the service life of the liner.
Because of the techniques commonly employed in using a liner in a GC instrument it is often desirable for the liner to be transparent. It is particularly important to be able to see through the walls of these liners which contain packing material in order to ensure its proper plug position within the internal bore of the liner and to be able to check for the presence of debris or other visual contaminants.
Various chemical coatings are applied to liners in order to reduce the degree of interaction between the sample and the surface of the liner. Sample-surface interactions may result in sample absorption in the coatings, decomposition of the coatings, and formation of new reaction products; in each case resulting in undesirable peaks (or loss of desirable ones) in detection measurements of the components contained in the sample being analyzed in the separation analysis. In addition to low sample-surface interactions, it is also desirable for the liner coating to be thermally stable in order to minimize background signal contributions originating from the liner coating itself detected by the analytical equipment. For glass substrate liners, common deactivation techniques include chemically treating the exposed silanol groups with organosilane reagents such as hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMCS), and trimethylchlorosilane (TMCS) [15].
Liners are manufactured from glass, primarily borosilicate, but also fused quartz, and less commonly from metal, mainly stainless steel [16].
The chemical composition of a quartz or fused silica liner is commonly 99.4-99.9% silicon dioxide (SiO2). The uppermost surface of the SiO2 silica contains a uniform, high concentration of silanol (Si—OH) groups. This represents the optimal surface with which to apply the deactivation chemistry described. An even distribution of silanol groups across the silica surface ensures a uniform deactivation coating which creates the most effective sample barrier [1].
While quartz is chemically the preferred material to make liners, the high melting point temperature (1650° C.) required to manipulate the cylindrical shape makes quartz practical strictly for straight tube liner designs (See Table 1)[17]. The difficulty in manipulating fused quartz into precision shapes has led to the need for subsequent machining or grinding operations on the stock tubing. While the initially drawn tubing is smooth and free of non-silica defects, these features are lost in subsequent processing. The risks of impurity introduction by machining or grinding, as well as the introduction of scratches and crevices, complicate production of optimal fused quartz liners for GC use.
Similar limitations are observed for sample vials manufactured from quartz. Quartz vials must be manufactured at temperatures higher than that required for borosilicate glass. Vials manufactured from quartz requires higher temperature furnaces and tooling having higher heat resistance. This greatly increases the costs for quartz vials as compared to those made from borosilicate glass or other glasses having comparatively lower softening points.
Laboratory borosilicate glass begins to soften at ca. 650° C., which enables comparatively low temperature thermoforming with which to create the complex shapes like those depicted in FIGS. 1 and 2A-2I. Pyrex borosilicate glass includes a relatively high concentration of non-silica moieties (ca.19%) including primarily boron, sodium, aluminum, and potassium. To create a pure silica surface wherein pure is defined as containing at least 90% wt. silica and hydroxylated silica, these contaminating species are generally removed by aqueous acid leaching prior to application of deactivation coatings [1]. The general commercial manufacturing stages for fused silica and borosilicate glass liners are described in
Acid leaching of the borosilicate glass article has been shown to leave a roughened silica enriched surface by solubilizing and removing the accessible domains enriched with non-silica components. The surface resembles that of silica gel following this leaching process with superficial pores commonly around 5 nanometers in average diameter, but which may be smaller or much larger for some specialty borosilicate glasses [18-23]. Because of sterile limitations within the thus-formed pores and crevices, a number of silanol groups are unreachable for coverage by the silane deactivation reagent. A lack of coverage completeness of the deactivation coating yields a population of residual active sites capable of interaction with analytes in the finished article. [1] There is a need in the field of gas chromatography for easily formable containers fabricated from glass and with a very low surface area pure silica surface suitable for effective chemical deactivation with traditional reagents.
In addition to silane treatments, another suitable deactivation coating is vapor deposited hydrogenated amorphous silicon, including the Siltek® Sulfinert® coatings [17, 24-26]. These coatings have been demonstrated on both borosilicate glass and metal surfaces, and in both cases it results in a semi-opaque mirror finish whose color is dependant on the coating thickness.
While chemically inert to many analytes, the Sulfinert® surface is not represented as being perfectly smooth. The creation of the amorphous hydrogenated silicon first layer takes place through decomposition of silane gas, and a layer of silicon may not completely cover the entire substrate surface after one silicon deposition cycle. The silicon deposition cycle is usually repeated several times to build up the passive layer of silicon to the requisite thickness. [25]. The surface morphology of these coatings has been studied and SEM data shows the presence of a textured surface for Silcosteel®, a related coating [27].
Liquid phase deposition of a silica film on glass sheets from fluorosilicic acid solutions under mild conditions was first described by Kawahara [28]. It was developed as an alternative to more costly sputtering and chemical vapor deposition techniques for large objects, and was shown to give a more dense silica coating than that obtained through selective leaching processes. The motivation for this work was to be able to economically alter the light reflecting properties of large glass sheets, as well as reduce alkali metal migration for battery, liquid crystal display, and solar cell applications, as well as to provide an electrically insulating layer for electronic devices.
The reversible reactions can be exploited to deposit, precipitate, and/or change composition through evaporative or distillative processes depending on choice of conditions. The equilibria of mixtures of fluorosilicic acid and silica have been explored in detail [29-33].
H2SiF6+2H2O⇄SiO2↓⇄+6HF
5H2SiF6+SiO2↓⇄3[H2SiF6.SiF4]+2H2O⇄3H2SiF6SiF4↑+2H2O
It is clear that several components are present in equilibrium in an aqueous solution of fluorosilicic acid. As these can vary in relative concentration, we refer to any stable, homogeneous liquid reaction product of silica, hydrogen fluoride and water in this invention as fluorosilicic acid. In the event that a change occurs which renders the homogeneous solution unstable with regard towards precipitation of solid silica in any form, the solution shall be referred to as being supersaturated with silica.
It is apparent from the equilibria described above that through increasing the relative concentration of a component through addition, or by reducing one by depletion, the balance can shift to either precipitate or dissolve silica [29, 34-85]. For example, addition of water to a silica saturated fluorosilicic acid solution renders it supersaturated, leading to solid silica precipitation or its deposition as a film [29, 68-85].
Much of the development done on silica based LPD has dealt with deposition on silicon and glass sheets. Silicon substrates have been extensively used with LPD in semiconductor manufacturing as a means of producing conformal insulating films with low dielectric constants. Film densities, impurity incorporation, the effect of annealing conditions and their associated influence on electrical behavior have been extensively studied. Studies involving deposition on glass have generally centered on altering visual properties, such as reflectivity or color.
Deposition of silica from fluorosilicic acid solutions is always accompanied by some level of fluoride incorporation in the film. A typical range is 1.8-6.25 wt. % [62, 74]. Conditions producing higher film growth rates produce higher fluoride concentrations. This is not just a surface phenomenon; rather the fluorine is resident throughout the film as treatment with boiling water has been demonstrated to have a limited effect on reducing bulk fluoride concentration [65].
Removal of fluorine following LPD from fluorosilicic acid solutions is possible at elevated temperatures. Thermal annealing is effective in facilitation of fluoride migration to the surface, where it is lost from the film to the gas phase. With treatment at ≧700° C. the fluorine is completely removed from the surface. While these conditions are acceptable to silica layers deposited on silicon substrates, these temperatures are sufficiently high so as to physically alter or deform the targeted dimensions of borosilicate substrates and should therefore be avoided. Because of this intolerance of high temperatures, a non-zero weight percent fluoride content on the surface of the borosilicate glass remains and can be used as an effective indicator that glass articles have been subjected to a LPD coating process employing fluorosilicic acid solutions. It is our opinion that the introduction of permanent fluoride contamination into LPD treated glass substrates may have previously served as a deterrent toward consideration of this type of coating by others skilled in the art for articles destined for use in the flow path of a chromatographic system.
The annealing induced outward migration of fluoride is accompanied by a densification of the film and reduction of porosity to levels approaching that of thermally deposited silica [74]. Annealing also reduces film stress values from those produced during the deposition process. Auger electron spectroscopy has been used to determine atomic composition depth profiles of LPD deposited and annealed coatings [44, 47, 71]. The thickness and refractive index of the LPD silica layer can be determined by ellipsometry [47, 57, 61, 71, 81, 83].
LPD based silica films from a saturated fluorosilicic acid solution have been demonstrated to yield smoother surfaces having a lower surface area per square unit of space as compared to untreated glass substrates. The technology is employed in the solid state electronics industry to planarize and smooth silicon-based substrates [35, 39].
In the same way it is important to minimize sample/liner interactions that can result in undesirable chemical reactions, decomposition, or permanent adsorption of the sample, it is equally important that the glass vessels used to store the sample prior to introduction to the GC inlet also have the same inert qualities. Common vessels employed in GC analysis to store samples include glass vials (generally for on-site prepared samples) [17] and ampoules (generally for sample standards or long term storage) [17]. Sample vials are commonly available made of borosilicate glass [17], less commonly quartz and much less commonly metal. Sample vials and ampoules are commonly used to contain samples in gas as well as liquid form. In the interest to further protect the chemical integrity of the samples being stored, often the vials are chemically deactivated using similar procedures as described for borosilicate liners [17].
Because the sample is at least temporarily contained in the liner until it is introduced into the GC column, the liner device itself can be described as a sample container within the GC sample path. For the purpose of this disclosure the term ‘container’ is used to describe any device employed to store or direct the sample throughout the GC analytical path and includes glass or metal sample vials, ampoules, cylinders, inlet liners, GC columns, or coupling devices employed to direct the sample to the GC detector.
Organic and organometallic compounds with useful optical and electronic properties have been used as dopants in porous Vycor glass [92-94].
Organic dyes have been infused into Vycor pores [95-97]. Unblocked pores containing dopants have been used in gas sensing applications [98]. The dopants have also been encapsulated by organic polymers within these pores [99-103].
The mild conditions required for the creation of sol-gel glasses is compatible with a wide range of dopants that constitute the same family as those described above for infusion into porous Vycor glass. Because of a lack of interconnected pores, the chromophoric species are usually present during the gelation process. Further ripening of the gel can take place without damaging the entrained dyes, salts, or chromophoric particles [104-110].
Dyes that produce a color change with temperature are referred to as thermochromic and have been the subject of extensive study [111-117]. A number of chemical classes exhibiting this behavior have been reported, and include perylene dyes, encapsulated leucodyes, and some inorganic compounds.
In addition, many photochromic compounds (those that change color on exposure to light at specific wavelengths) exhibit thermochromic behavior. Some examples of this class of compounds include spiropyrans, spiroxazines, and ethylene aromatics, and the color change is due to often reversible molecular rearrangements giving rise to differences in conjugation or ionic structure. Thermochromic and photochromic indicators have been introduced into both porous Vycor glass, and sol-gel glasses, with the polarity and geometric constraints in their vicinity affecting the stabilization of one isomeric form over another. Thus environmental effects can result in thermochromic or reverse thermochromic behavior with the same dye molecule. Encapsulation of the dyes within the pores of these inorganic glass matrices has been reported using polymethylmethactylate to yield transparent composites with the anticipation that they could lead to the development of three-dimensional high density memory arrays [108].
The thermochromic effect can be gradual, with the color intensity varying with the percentage of (lye molecules in each state. Photochromic images previously set through light exposure can sometimes be erased through thermochromic relaxation.
We present here a borosilicate-based liner or container before deactivation having a smooth, high purity silica uppermost surface, where the uppermost surface is deposited using a liquid phase deposition process, where high purity silica is defined as having less than a total of 10% of a combination of boron oxides, and metal or other element oxides besides silicon on a mass basis. We thus disclose a superior process to standard leaching technologies as the leaching process leaves behind a comparatively high surface area, high surface energy substrate, which can compromise the completeness and uniformity of the final liner or container's deactivation coating.
We also describe a method of annealing that is adequate to remove contaminating fluoride concentrations to acceptable levels so as not to interfere with subsequent deactivation processes. We also define the uppermost surface of the liner or container as the region extending inward from zero to 100 nanometers from the surface of the article. For the purpose of this disclosure the uppermost layer may result from multiple repeat LPD cycles on the same substrate. The term ‘layer’ and ‘uppermost layer’ may refer to at least one layer deposited on the substrate surface, with more than one layer being present next to or on top of one another.
We further present the application of LPD based silica films, with a subsequent deactivation process, with glass containers used for handling or storing chemical samples.
Previously, liners employing color indicators have been demonstrated using porous glass substrates [14]. Similar practice has been demonstrated here where the indicator is incorporated into the LPD layer, which can be deposited on both porous and non-porous containers [86-91].
We further present a borosilicate liner or container having a smooth, high purity silica uppermost surface, where the uppermost surface incorporates an indicator.
We further present a borosilicate liner or container having a smooth, high purity silica uppermost surface, where the uppermost surface incorporates multiple overlaying layers where at least one of the layers incorporates an indicator.
We further present a liner or container having a deposited high purity silica layer, which employs indicators within the silica layer as a means to easily identify one liner or container from another. For the purpose of this disclosure the term indicator relates to any element, compound, dopant, or mixture additive to the glass substrate that modifies the native color or transparency of the glass substrate.
We further present here a liner or container having a deposited high purity silica layer which employs indicators as a means of visually identifying the thermal state of the liner.
We further present here a liner or container having a deposited high purity silica layer which employs indicators as a means of determining “use status”, wherein it is possible to visually identify if the liner or container has been previously subjected to high temperature and optionally the duration of exposure beyond a specific threshold.
We further present here a liner or container having a deposited high purity silica layer which employs indicators with controlled physical placement as a means of identifying the orientation of the liner.
We further present here a liner or container having a deposited high purity silica layer which employs colored indicators that are visible under ordinary and/or ultraviolet light as a means of decoration, identification, or counterfeit detection.
In addition, we present a liner or container having a deposited high purity silica layer wherein the indicators are effectively blocked from surface interactions through thermally stable chemical capping.
We further present a liner or container having a deposited high purity silica layer which employs indicators receptive to photolithographic imaging.
a represents the general manufacturing process (Scheme 1) for quartz liners,
In one preferred embodiment of this invention as illustrated in
The resulting liner or container is thus coated with a film exhibiting the properties shown in Table 1, and is finally deactivated with silanes using procedures described in the art.
In
In
The liner represented in
The liner illustrated in
The liner illustrated in
The peaks are identified on the chromatogram with their absolute area counts in parentheses, and the bulk endrin and DDT concentrations in the test mixture were 50 and 100 pg/μL respectively. The identification of the eluted peaks and their absolute area counts was based on previous studies with internal standards. In this experiment, the endrin breakdown was found to be 0.62%, which may be considered a baseline value for this particular standard using the separation column and conditions indicated.
Inlet temperature: 250° C., Splitless injection, at 20 mL/min @ 0.5 min, constant flow @ 1.5 mL/min, helium carrier
Column: 20 meter, 0.18 mm ID, 0.18 μm film, Rxi-5sil-MS
Detector: μECD, 300° C., N2 make-up gas flow of 60 mL/min
The same analytical standard was used for the analysis, and 1 μL was injected. The endrin breakdown level was found to be 15.8% and that of DDT to be 4.3%. The difference in breakdown levels from those found in
Inlet temperature: 220° C., Splitless injection, 15 sec. hold time, 20 mL/min purge flow, column flow @ 1.5 mL/min, helium carrier
Oven: 120° C. (hold 1 min.) to 225° C. @ 20° C./min to 280° C. @ 6° C./min. (hold 7 min)
Column: 20 meter, 0.18 mm ID, 0.18 um film, Rxi-5-MS
Detector: μECD, 290° C., N2 make-up gas flow of 60 mL/min
The endrin breakdown level was found to be 2.8% and that of DDT to be 1.2%. The difference in breakdown levels from those found in
The endrin breakdown level was found to be 1.9% and that of DDT to be 1.0%. The difference in breakdown levels from those found in
The chromatogram depicted in
Inlet: 250° C., Constant pressure at 50 psi, Splitless injection, split flow @ 20 mL/min @ 1 min
Column: 15 m, 0.25 mm ID, 0.25 um film, Rxi-5MS
Detector: FID, 300° C., H2 @ 40 mL/min, Air @ 450 mL/min, N2 @ 45 mL/min
The sample was 1 μl, of a 10 ng/μL solution of 2,4-dinitrophenol and 10 ng/μL of acenaphthene
The following examples are presented to show various aspects of the process of the invention.
In this example, simple coloration of a single gooseneck borosilicate glass liner, illustrated in
A non-cationic dye was utilized as a colored indicator, even though it has limited water solubility in its acid form, but still exhibiting an intense fluorescence. A silica saturated fluorosilicic acid (SSFA) solution prepared as in Example 1 above was filtered and diluted with an equal volume of an aqueous solution saturated with fluorescein. A liner as in Example 1 was immersed in the solution and agitated periodically over 16 hours. The liner was removed from the solution, rinsed well with water and dried. It appeared almost colorless, but exhibited some visible fluorescence when illuminated with ultraviolet light.
A SSFA solution prepared as in Example 1 above was filtered and diluted and mixed with an equal volume of a 0.2% solution of Crystal Violet dye in water. Crystal Violet is a member of the family of triphenylmethane cationic dyes, whose color is a function of the local pH. A liner was treated with this solution as in Example 2. It exhibited a transparent light blue color. The liner was rinsed well with water until neutral pH was achieved and no dye was extractable from the glass surface. The liner was then dried in a forced air oven. After overnight treatment at 200° C., the color was as before, with no visible change having occurred.
A liner was treated as in Example 3 above, but with Malachite Green oxalate (another cationic dye from the triphenylmethane family) as the dye. It exhibited a transparent dark green color. The liner was rinsed well with water until neutral pH was achieved and no dye was extractable from the glass surface. The liner was then dried in a forced air oven. After overnight treatment at 200° C., the color was as before, with no visible change having occurred.
Examination of less thermally stable dyes as thermochromic indicators was demonstrated in this example. A borosilicate glass liner was treated as in Example 3 above, but with the phenothiazine compound Methylene Blue hydrate as the dye. It exhibited a transparent dark blue color. The liner was rinsed well with water until neutral pH was achieved and no blue dye was extractable from the glass surface. The liner was then dried in a forced air oven. After overnight treatment at 200° C., the color was gone, leaving the liner clear and colorless.
A liner was treated as in Example 3 above, but with anionic Methyl Orange as the dye. It showed no visible evidence of dye incorporation. This result is consistent with reports in the literature that cationic dyes are more likely to be incorporated in the growing silica film than anionic ones.
A liner was treated as in Example 3 above, but with another anionic compound, Trypan Blue as the dye. It showed, no visible evidence of dye incorporation. This result is consistent with reports in the literature that cationic dyes are more likely to be incorporated in the growing silica film than anionic ones.
Dyes with higher thermal stability and thermochromic behavior as indicators were utilized in the following example. A borosilicate glass liner was treated as in Example 3 above, but with Neutral Red as the dye. It exhibited a transparent brick red color. The liner was rinsed well with water until neutral pH was achieved and no dye was extractable from the glass surface. The liner was then dried in a forced air oven. After overnight treatment at 200° C. in air, the color was as before, with no visible change having occurred. The temperature was increased to 400° C. and the liner was examined after 1 hour exposure. It had turned a transparent light brown color. Heating was continued at 400° C. in air and the liner periodically examined for color change. None occurred and the experiment was terminated after 72 hours accumulated heating time at 400° C.
The effect of the LPD process with wool present inside the liner, along with annealing and deactivation were demonstrated in the following example. A single gooseneck borosilicate glass liner was loaded with 6 mg of 4 μm (nominal fiber diameter) fused quartz wool and leached with 3M HCl solution for 30 minutes. The acid was removed by rinsing with water until the pH was neutral. The liner was then oven dried at 120° C. for 30 minutes. The initially smooth glass surface was noticeably rougher after the acid leaching process as determined by physical feel.
Silica saturated fluorosilicic acid solution prepared in Example 1 was allowed to warm to room temperature and was held for 24 hours. The excess silica was removed by filtration and 20 mL of this solution was placed in a plastic tube. The solution was diluted with 20 mL of water that had 2 drops of a 0.2% Rhodamine B solution added to it. After mixing well, the acid leached liner was immersed in the solution and allowed to stand 6 hours with occasional swirling. The liner was then removed from the solution and rinsed with water until the pH was neutral. A faint pink transparent coloration of the glass was observed, with more intensity of color on the wool surface. The rough surface had also developed a very smooth feel as a result of the deposition treatment. The liner was placed in a stainless steel vessel, purged with helium, and heated to 250° C. for 5 hours to anneal the freshly deposited silica and reduce the overall fluoride content. The liner was then deactivated using standard reagents and processes and evaluated for inertness by gas chromatography. Results are shown in
A SSFA solution prepared as in Example 1 above was filtered, diluted and mixed with an equal volume of water. Two drops of Rhodamine B solution (0.2% in water) was added, and a single gooseneck liner was immersed in the solution and the plastic vessel containing it was closed. The vessel was placed in an oven at 35° C. and within 2 hours pink particles had formed and coated both the inside of the vessel and the liner. The liner itself showed a pink coloration similar to the liner from Example 9 after water rinsing and drying, but with a significant haze. The surface of the liner was also much rougher in feel than the liner from Example 9. This example demonstrated the effect of combined dilution and heating in one step. Homogeneous nucleation occurred from the supersaturation level being too high, such that particle formation competed with film growth.
In this example, the LPD solution was not diluted with an equal volume of water, but was heated in order to effect silica supersaturation. A SSFA solution prepared as in Example 1 above was filtered and mixed with two drops of Rhodamine B solution (0.2% in water). A single gooseneck liner was immersed in the solution in a closed plastic vessel. The vessel was placed in an oven at 35° C. and allowed to heat overnight. The vessel was cooled and the liner rinsed well with water until pH neutral. The liner was transparent with a transparent light pink color and exhibited no sign of haziness, indicating that only film formation occurred without homogeneous nucleation. The liner surface was shiny and smooth.
Physical blocking of the glass surface by a hydrophobic mask was used in this example to demonstrate the need for LPD solution contact with the glass surface for film formation to occur. A single gooseneck liner was immersed to a depth of 1 inch into melted paraffin wax and then removed. After the wax had hardened, the liner was immersed into an SSFA solution as in Example 3, but containing Rhodamine B as the dye. After the deposition treatment, the liner was rinsed with water, and then hot toluene. The pink clear coating was only present where the contact with the wax had not occurred, the latter having served as an effective mask against silica deposition.
Multiple thermochromic indicators in multiple deposition steps were used in this example. The partially coated liner from Example 12 was immersed in an SSFA solution containing methylene blue as in Example 3, but with about 10% of the dye concentration. The liner was then rinsed well with water and dried. The liner exhibited a blue color in the region where the wax mask had originally been, and a purple color where the Rhodamine B had already been deposited. It was then placed into an oven exposed to air and heated in increments of 50° C., holding for 30 minutes at each temperature. The first noticeable changes occurred at 200° C. The light blue liner had lost the Methylene Blue dye component, leaving behind a pink Rhodamine B color in the originally dyed region. The pink color remained until the temperature testing reached the 400° C. hold step, when it became clear and colorless. The stepwise color loss demonstrated an irreversible maximum temperature indicating thermochromic effect.
In another example of multiple thermochromic indicators, but co-deposited within the same film, a borosilicate glass single gooseneck liner was immersed in an SSFA solution containing a mixture of methylene blue and neutral red dyes as in Example 3. The liner was then rinsed well with water and dried. It was dark purple in color and smooth. It was placed in an oven and heated gradually to 400° C. using the process described in Example 13. At 200° C., the dark blue liner turned much darker, appearing almost black. The dark liner remained black until the hold at 350° C. where it turned dark brown. This corresponded to the decomposition of the heavily doped methylene blue dye leaving only the neutral red dye. On continued heating to 400° C., the liner turned a light brown color similar to that seen with the liner in Example 8. The stepwise color change in this Example thus demonstrated an irreversible maximum temperature indicating thermochromic effect.
The effect of deposition of silica using the process of this invention on surfaces other than silica was shown in this example. A single gooseneck liner was labeled with a silkscreened ceramic glaze decal and heated in a muffle furnace at 550° C. for several hours to fuse the pigment into the glass surface. After cooling, the liner was immersed into an SSFA solution as in Example 3 above, but with Rhodamine B as the dye. It exhibited a pink color. After rinsing and drying, the liner was examined for signs of etching or attack on the inorganic pigment. None was apparent, and the image resolution was not affected. The liner was now smooth over its entire surface, where the image had imparted a rough feel before. Microscopic examination revealed the presence of a smooth, conformal pink film over the entire article.
A single gooseneck borosilicate glass liner was loaded with 4 μm fused quartz wool and treated the same as the liner in Example 9, but with the omission of the Rhodamine B indicator. The treatment provided a very smooth and colorless liner. When tested chromatographically for inertness, this liner gave essentially identical results compared to the performance of the light pink colored liner produced in Example 9.
In this example, the interior of a sample vial is deactivated using one preferred embodiment of this invention. A 40 mL borosilicate glass screw cap vial was filled with 3 N hydrochloric acid and allowed to stand for 30 minutes. The solution was removed and the vial was rinsed with deionized water until neutral pH was obtained. Silica saturated fluorosilicic acid solution prepared in Example 1 was allowed to warm to room temperature and was held for 24 hours. The excess silica was removed by filtration and 20 mL of this solution was placed in the acid leached vial. The solution was diluted with 20 mL of water that had 2 drops of a 0.2% Rhodamine B solution added to it. The vial was capped, mixed well, and allowed to stand 6 hours with occasional swirling. The solution was then removed and the vial rinsed with water until the pH was neutral. A faint pink transparent coloration of the glass was observed.
The vial was placed in a stainless steel vessel, purged with helium, and heated to 250° C. for 5 hours to anneal the freshly deposited silica and reduce the overall fluoride content. The vial was then deactivated using standard reagents and processes. The light pink coating on the vial interior was very smooth and repellant to liquid water. Acetone was added to the midpoint of the vial, which was then capped. The solution showed no hint of dye leaching after 3 weeks exposure to the solvent.
The references referred to in this application and listed below are hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US10/03175 | 12/15/2010 | WO | 00 | 12/3/2012 |
| Number | Date | Country | |
|---|---|---|---|
| 61284231 | Dec 2009 | US |
