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Filter papers for EPA Method 353.2
We've experienced some trouble while running nitrate (NO3) by automated colorimetry using EPA Method 353.2. There seemed to be an interference from the filter paper that results in a false positive. We've noticed that the false positive was not seen when analyzing for NO2. The filter paper used is Whatman filter paper 541 - Hardened Ashless. Is there a more appropriate filter paper?
Created: 06/14/19 10:09:51
Created By: "admin"
1 2430
Filter papers for EPA Method 353.2
We've experienced some trouble while running nitrate (NO3) by automated colorimetry using EPA Method 353.2. There seemed to be an interference from the filter paper that results in a false positive. We've noticed that the false positive was not seen when analyzing for NO2. The filter paper used is Whatman filter paper 541 - Hardened Ashless. Is there a more appropriate filter paper?
Posted: 06/14/19 10:10:29
Analyzing the mineral composition of concrete
I need to analyze the mineral composition of concrete, and wondered if you had any recommendations for what approaches I should follow?
Created: 06/14/19 10:08:26
Created By: "admin"
1 2434
Analyzing the mineral composition of concrete
I need to analyze the mineral composition of concrete, and wondered if you had any recommendations for what approaches I should follow?
Posted: 06/14/19 10:09:03
HF best way to keep W in solution
We are using your Tungsten (W) standard and are having trouble keeping the tungsten in solution. We would prefer not to use HF due to safety concerns. We use a matrix of 2% HNO3 and dilute your standard to 0.1, 1, 5, and 10 ppm for standards. We calibrate W separately due to stability issues. Usually if we make the standards fresh daily, everything runs fine. We are having trouble with LCSs and matrix spikes that have gone through an EPA 3050 method digestion. We have tried with and without HCl in the final 3050 step. Adding HCl made the LCS lower than without using it. Can you give me any tips or tricks to stabilize W without using HF?
Created: 06/14/19 10:06:20
Created By: "admin"
1 2177
HF best way to keep W in solution
We are using your Tungsten (W) standard and are having trouble keeping the tungsten in solution. We would prefer not to use HF due to safety concerns. We use a matrix of 2% HNO3 and dilute your standard to 0.1, 1, 5, and 10 ppm for standards. We calibrate W separately due to stability issues. Usually if we make the standards fresh daily, everything runs fine. We are having trouble with LCSs and matrix spikes that have gone through an EPA 3050 method digestion. We have tried with and without HCl in the final 3050 step. Adding HCl made the LCS lower than without using it. Can you give me any tips or tricks to stabilize W without using HF?
Posted: 06/14/19 10:06:57
Tin and thallium soil extraction
I have been doing some method development on Sn and Tl in soils, and noticed that the recovery on various CRMs is very low. We've performed both both nitric acid and aqua regia preps. Can you offer any suggestions as to why we have low recoveries?
Created: 06/14/19 10:04:29
Created By: "admin"
1 2294
Tin and thallium soil extraction
I have been doing some method development on Sn and Tl in soils, and noticed that the recovery on various CRMs is very low. We've performed both both nitric acid and aqua regia preps. Can you offer any suggestions as to why we have low recoveries?
Posted: 06/14/19 10:05:33
Procedure for measuring palladium in mesoporous silica
I would like to use ICP-MS to measure the concentration of palladium in mesoporous silica, specifically SBA-15. SBA-15 is the mixture of a triblock copolymer and tetraethyl orthosilicate (TEOS, C8H20O4Si). For TEOS, the boiling point is 163 - 167 °C, ignition temperature is 230 °C, and no melting point is provided. Do you have recommendations for sample prep, etc.?
Created: 06/14/19 10:02:38
Created By: "admin"
1 2279
Procedure for measuring palladium in mesoporous silica
I would like to use ICP-MS to measure the concentration of palladium in mesoporous silica, specifically SBA-15. SBA-15 is the mixture of a triblock copolymer and tetraethyl orthosilicate (TEOS, C8H20O4Si). For TEOS, the boiling point is 163 - 167 °C, ignition temperature is 230 °C, and no melting point is provided. Do you have recommendations for sample prep, etc.?
Posted: 06/14/19 10:03:14
Leaching silicon from graphite
I was wondering what would be a valid procedural method to adequately leach Silicon from a natural flake graphite (most likely in the form of SiO2)?
Created: 06/14/19 10:00:49
Created By: "admin"
1 2240
Leaching silicon from graphite
I was wondering what would be a valid procedural method to adequately leach Silicon from a natural flake graphite (most likely in the form of SiO2)?
Posted: 06/14/19 10:01:33
Mercury (Hg) analysis in dimethyl sulfoxide (DMSO)
I am working on developing a method to analyze trace amounts of Hg in DMSO. My proposed specification level is 100 µg/g. I have an ICP-OES, ICP-MS, or CVAAS available for instrumentation. I'm not sure what I should do for sample prep, do you have any ideas?
Created: 06/14/19 09:58:26
Created By: "admin"
1 2488
Mercury (Hg) analysis in dimethyl sulfoxide (DMSO)
I am working on developing a method to analyze trace amounts of Hg in DMSO. My proposed specification level is 100 µg/g. I have an ICP-OES, ICP-MS, or CVAAS available for instrumentation. I'm not sure what I should do for sample prep, do you have any ideas?
Posted: 06/14/19 09:59:04
Digestion method for molybdenum carbide
My sample contains platinum on Mo2C. I need to quantify both Pt and Mo. Could you please let me know what solution can I use to dissolve Mo2C?
Created: 06/14/19 09:57:04
Created By: "admin"
1 2216
Digestion method for molybdenum carbide
My sample contains platinum on Mo2C. I need to quantify both Pt and Mo. Could you please let me know what solution can I use to dissolve Mo2C?
Posted: 06/14/19 09:57:35
Fusions for Ti analysis in rubber
I was reviewing your Sample Preparation Guide regarding the fusing process for Titanium Oxides. I am wondering if you could clarify a few points or maybe offer some advice regarding for our case. We are trying to measure the Ti level in vulcanized rubber samples, with the source being TiO2. We currently possess an MP-AES instrument which is not compatible with HF, so we are looking into the fusion techniques with pyrosulfate. We plan to ash the rubber sample at 850-900 C so that should put the Ti in the brookite form. We then plan to fuse the residue with pyrosulfate prior to digestion and analysis on the MP-AES. I have two questions regarding these steps. 1) When fusing the samples with potassium pyrosulfate, I see the ashing guide recommends 500 C, but for how long do you recommend? We possess a fluxer so the heating and agitation is automated. 2) The guide indicates that the fuseate is soluble in acids such as 30% sulfuric. For the MP-AES, we would prefer to be in dilute nitric acid or dilute aqua regia. Do you think the fuseate would be soluble in concentrated nitric or concentrated 1:3 nitric + HCl? Also, do you think the material will be stable once diluted to 2% nitric or dilute 1:3 nitric + HCl (~ 1% nitric & 1.6% HCl), which are the typical run conditions?
Created: 06/14/19 09:47:28
Created By: "admin"
1 2214
Fusions for Ti analysis in rubber
I was reviewing your Sample Preparation Guide regarding the fusing process for Titanium Oxides. I am wondering if you could clarify a few points or maybe offer some advice regarding for our case. We are trying to measure the Ti level in vulcanized rubber samples, with the source being TiO2. We currently possess an MP-AES instrument which is not compatible with HF, so we are looking into the fusion techniques with pyrosulfate. We plan to ash the rubber sample at 850-900 C so that should put the Ti in the brookite form. We then plan to fuse the residue with pyrosulfate prior to digestion and analysis on the MP-AES. I have two questions regarding these steps. 1) When fusing the samples with potassium pyrosulfate, I see the ashing guide recommends 500 C, but for how long do you recommend? We possess a fluxer so the heating and agitation is automated. 2) The guide indicates that the fuseate is soluble in acids such as 30% sulfuric. For the MP-AES, we would prefer to be in dilute nitric acid or dilute aqua regia. Do you think the fuseate would be soluble in concentrated nitric or concentrated 1:3 nitric + HCl? Also, do you think the material will be stable once diluted to 2% nitric or dilute 1:3 nitric + HCl (~ 1% nitric & 1.6% HCl), which are the typical run conditions?
Posted: 06/14/19 09:48:01
Potassium pyrosulfate fusion of titanium oxide
What are the proper temperature and time in the fusion process?
Created: 06/14/19 09:45:08
Created By: "admin"
1 2197
Potassium pyrosulfate fusion of titanium oxide
What are the proper temperature and time in the fusion process?
Posted: 06/14/19 09:45:46