A one liter sample or standard with minimal suspended solids present will take about 50 minutes to complete the test. The filtration time for such a sample is about 5 minutes with a 10 minute vacuum pull after that to remove residual water from the SPE disc. A significant increase in solids will only affect the actual sample filtration time. The rest of the analysis will be unaffected.
According to Method 1664A, (although they are using glassware, not aluminum pans) they require a second weight be aquired. How is the pan to be reheated after evaporation in the chamber?
The chambers can be used in manual mode to reheat the evaporation pans. The user is free to set the temperature and leave the pans in the chamber for whatever amount of time is required. The exact drying time is available from the sample report to use for guidance. You may find it advantageous to update your method to 1664B. It changes the replicate weighing requirements as follows – “While at room temperature and without additional heating, repeat the cycle of desiccating and weighing…”
We have made a rough estimate of between $6 and $7 per sample for the operating costs. This figure only includes the reagents/chemicals used and the consumables. We do have a cost justification spreadsheet that we can use to compare your current method to the SPE-Express. Please contact your sales representative so that they can go over that numbers for some more detailed information.
No, the instrument is only available as a 3-station model.
Relative to the question on the extraction of a 2 liter sample, is there room for the larger bottle and still have all 3 stations usable. The larger bottles have a circumference of nearly 17 inches
A bottle that size will not fit onto the bottle head. We are limited to a diameter of 4.5 inches and a height of 8.5 inches.
As long as the thread size (53 mm GL38 is the standard, other options are available) is compatible with the attachment the unit will be able to handle any volume used. Obviously, larger volumes will require longer filtration times. The instrument automatically detects when the filtration is complete so this does not place any additional burden on the operator.
Is this for Oil and Grease or can it do total petroleum hydrocarbons (TPH, non-polar material)portion as well?
The instrument will only do the Oil and Grease (HEM) portion of the test. We do not have a way to automate the silica gel treatment as of yet. Once the analysis is complete you will need to add more hexane to the pan to redissolve the extracted material and do the SGT by hand. The resulting extract can then be evaporated inside the SPE-Express using the manual operation screen.
The EPA no longer approves specific pieces of equipment. As long as the instrument is capable of adhering to the approved method it is acceptable for use. With that being said, the SPE-XPress follows all the steps laid out in EPA1664 as it pertains to solid phase extraction. There are only three true consumables for the instrument; the SPE filter, the sodium sulfate drying cartridge, and the drying pan to collect the solvent during extraction. There are a few o-rings that will need periodic replacement as they wear, but that will depend entirely on usage.
The unit is self enclosed and does not need to be used under a hood. It has a ventilation duct that does need to be routed into a fume hood or other exhaust system. We currently do not have any way to recover the hexane during the evaporation step.
We are not doing any individual lab demos at this moment. We do have a tech tip video that shows the operation of the unit and some of its advantages. You can see that by selecting the appropriate link at http://www.envexp.com/video. If you have further questions please contact a member of the sales team.
No, that will not present any problems. The software does not do any of the sample calculations for you at this time. It only tracks the method and conditions used to do the actual extraction. The operator must separately track and calculate the pan weights, sample volume, and final result.
The drying cartridges are single use only. Please consult the SPE-XPress accessories page (http://www.envexp.com/component/envexp/1-Wet_Chemistry/SS-Oil_and_Grease_EPA_1664/SPEX2-SPE-XPress_Accessories/G1065-SPE_-_5_5_Gram_Na2SO4_Drying_Cartridge%2C_50pk)or call any member of our sales team to find the current pricing on the cartridges.
This system is not designed for use with solid matrices. A soxhlet extraction would be more applicable.
How about the sample with lots of suspended solid? Will they be filtered porperly? How Is sodium sulfate tube drying efficiency?
The instrument uses a liquid level sensor in the sample bottle to determine when all sample has been filtered. The filtration step will continue until that sensor detects no more free liquid in the sample container. If the sample contains large amounts of suspended solids you may experience an extended filtering cycle, but the instrument will filter all of it. In our testing we tried to find a sample with enough solids content that would halt the filtering process but every one finished. The sodium sulfate tubes contain 5.5 g of the salt and are just as efficient as that amount of salt would be under normal circumstances. I believe the molar ratio of sodium sulfate to water absorbed is 10.
This certainly will depend on how turbid of a sample you are dealing with but a good average total time from start to finish would be around 50 - 60 minutes.
The beta testing site was a municipal water treatment plant so the turbidity of the samples tested varied greatly from relatively clean to very turbid (effluent and influent samples). The jars used are the ones mentioned in method 1664 though adaptors are available for other sized openings.
The unit does not measure sample volume. The sample volume is user-defined and must be input into the software program as one of the steps before running the extraction procedure.
We use wide-mouth sample jars. Do you have an adapter? I don\'t see any solvent jars. How is the solvent delivered or are they just not hooked up in the picture?
Adaptors are available for other size sample jars. Contact us at email@example.com for specific sizes. Solvents are added using nitrogen to create a positive pressure for injection. This is not pictured on the web but if you look at the technical data sheet you can see a drawing of where the nitrogen line is hooked up and where the reagent inlet lines are located.