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1. What is CElixirOA™?



2. What is the pH range of CElixirOA™?



3. What is the UV wavelength that I should use for CElixirOA™?



4. What would you suggest for Internal Standards for the 8.2.Kit?



5. What is the buffer concentration of CElixirOA™?



6. I have a successful method for separation of Nitrite from Nitrate using CElixirOA™ 2.5. I seem to be getting an interference with some Cl that is also present. How can I minimize this interference?



7. I am using CElixir-pH™ and I want to use CElixirOA™ on the same capillary. Can I do this?



8. Is there anything in CElixirOA™ that can pit or damage a bare fused silica capillary in any way?



9. I want to use CElixirOA™ to analyze Nitrite and Chromate in urine. Which Kit/pH should I use?



10. I have been successfully using CElixirOA™ for the separation of Nitrite from Nitrate. After a day or do, I begin to lose one of my peaks. What could be the cause of this? When I use fresh sample, I have two peaks again.



11. I have samples of amino acides that are provided to me in high acidic matrix. I would like to avoid desalting them, will this work with CElixirOA™?



12. I am using a very large sample plug (20 psi seconds) which is diluted 1:10 and 1:20 in water. I notice that in the beginning of the run the current is rather low. The current gradually increases then stabilizes. Is this normal?



13. Can I use 254nm as my wavelength with CElixirOA™?



14. Can temperature have an effect on CElixirOA™?



15. Indirect detection will produce “negative peaks”. Is it possible to view and print these as “normal peaks”?



16. Is CElixirOA™ a double layer dynamic coating like CElixir-pH™?



17. I am using CElixirOA™ very successfully except I am getting a “staircase” profile in my e-gram. What can I do to eliminate this?



18. Can I use CElixirOA™ for the analysis of Cyanide?



19. Can I use CElixirOA™ for the analysis of Flouride?



20. How do you calculate the limit of detection for a CE method using CElixirOA™?



21. I am analyzing wine, will the limit of detection (LOD) when I use CElixirOA™ allow for the proper analysis of common organic acids and anions in wine?



22. Can I use CElixirOA™ for the analysis of Bromide?



23. What are the concentrations of each of the components in the 3 different anions test mixtures?



24. What is the best solvent to use as diluent with CElixirOA™?



25. I have great separation with CElixirOA™ but I would like to sharpen my peaks a little. What do you suggest?



26. My migration times correlate very well with the migration time data posted on your website for the first 4 anions of the test mixture. However the last 6 migrate increasingly longer than what is posted. Is this normal? I used a 60cm capillary followed by the conditioning directions and ran the method. What do you suggest?

1. What is CElixirOA™? [top]
CElixirOA™ is a kit of pre-made buffers that are used to separate negatively charged molecules. The kit uses a dynamic coating in order to reverse the EOF so that inverse polarity can be used. Since several anions and organic acids are non UV absorbing an absorbing buffer is used with inverse detection mode on your instrument. For other molecules that will absorb UV light we offer a normal phosphate buffer with direct UV absorption.

2. What is the pH range of CElixirOA™? [top]
In order to cover a wide range of applications CElixirOA uses buffers at different pH. The most popular is CElixirOA 5.4 where the pH is optimal for the separation of most common organic acids.
With CElixirOA 8.2 Carbonate can be analyzed. The more alkaline pH makes it also possible to increase the selectivity for some analytes. For example, it is possible to separate propionic from sebacic acid, iso-citric from citric acid and 2-ethyl-hexanoic acid from octanoic acid.
CElixirOA 2.5 at pH 2.5 can be used for separation of UV absorbing anions such as bromide, bromate, chlorite, chlorate, nitrate, nitrite as well as maleic, oxalic, tartaric, fumaric acid and others.
Although these kits are available in three separate pH settings (2.5, 5.4 and 8.2) to achieve unique separations they can be adjusted as long as you stay within the capacity of the buffer.

3. What is the UV wavelength that I should use for CElixirOA™? [top]
The chromophore in the buffer is maximized at 233nm but it will also work with a UV filter at 254 nm and of course with a filter of 230nm.

4. What would you suggest for Internal Standards for the 8.2.Kit? [top]
For CElixirOA 5.4 and 8.2 you have different choices: you can use chlorite or bromide at the beginning of the separation, acetate in the middle and octanoic (C8) or lauric (C12) at the end. For CElixirOA 2.5 tosylate is an option.

5. What is the buffer concentration of CElixirOA™? [top]
CElixirOA™ 2.5 contains Aqueous Phosphoric Acid/Tris Buffer (135mmol/L). CElixirOA 5.4 is Aqueous Pyridine-Dicarboxylic Acid/Tris Buffer (80mmol/L for Inititator and 75mmol/L for the Accelerator). CElixirOA™ 8.2 is Aqueous Pryidine-Dicarboxylic Acid/Tris Buffer (105mmol/L).

6. I have a successful method for separation of Nitrite from Nitrate using CElixirOA™ 2.5. I seem to be getting an interference with some Cl that is also present. How can I minimize this interference? [top]
At 200nm direct detection using CElixirOA™ 2.5, you will see at high Chloride concentration that chloride will still absorb. To minimize this you can simply change the UV wavelength to 214nm. Another strategy would be to dilute your sample as much as possible to decrease the Cl signal. Do not dilute to a point where the NO3 signal will be lost. Also, using the dilution strategy along with a longer capillary to increase the separation between Cl and NO3 might help as well.

7. I am using CElixir-pH™ and I want to use CElixirOA™ on the same capillary. Can I do this? [top]
Yes, but it is recommended to use a separate capillary for optimal performance, however you could use following conditioning of the capillary.

1. Rinse the capillary for 1 minute with 0.1N NaOH.
2. Wait for 5-10 minutes with NaOH in the capillary.
3. Rinse again with 0.1N NaOH.
4. Discard the first 2-3 runs with the new method.

9. I want to use CElixirOA™ to analyze Nitrite and Chromate in urine. Which Kit/pH should I use? [top]
To separate Nitrite from Chromate in Urine, it is recommended to use CElixirOA™ 2.5 in reverse polarity with indirect detection mode on your instrument. The signal should be analyzed at 214nm.

10. I have been successfully using CElixirOA™ for the separation of Nitrite from Nitrate. After a day or do, I begin to lose one of my peaks. What could be the cause of this? When I use fresh sample, I have two peaks again. [top]
The answer may be that your Nitrite peak is degrading into Nitrate which is normal. Fresh sample must be used if this is what is happening.

11. I have samples of amino acides that are provided to me in high acidic matrix. I would like to avoid desalting them, will this work with CElixirOA™? [top]
No, high salt concentrations will cause a very high current in the sample plug and will adversely effect the analysis. This is not limited to CElixirOA™ but for any CE method.

12. I am using a very large sample plug (20 psi seconds) which is diluted 1:10 and 1:20 in water. I notice that in the beginning of the run the current is rather low. The current gradually increases then stabilizes. Is this normal? [top]
No, what may be happening is that since the sample plug is extraordinarily large and the sample is further diluted with water, it will take time for sample plug to become totally ionized. During this time the current will be low. We suggest that you dilute your sample in the 5mM NaOH solution.

13. Can I use 254nm as my wavelength with CElixirOA™? [top]
Yes, but the maximum for sensitivity is 233nm for most molecules. However, we have seen 254nm to be best for nitrate analysis.

14. Can temperature have an effect on CElixirOA™? [top]
Yes, CElixirOA™ 5.4 and 8.2 are made with a Tris buffer. Since a 10°C change in temperature can effect a 0.3pH unit drop, this may effect your separation. You can bring the pH higher by adding solid Tris to CElixirOA™ in very small amounts at a time but caution should be used using this technique.

15. Indirect detection will produce “negative peaks”. Is it possible to view and print these as “normal peaks”? [top]
Yes, using the software of most modern CE instruments, find the setting for “Indirect Detection” and the peaks appear as if they were absorbing UV in normal mode.

16. Is CElixirOA™ a double layer dynamic coating like CElixir-pH™? [top]
No. The Initiator Solution contains a poly cation to create the reverse polarity needed. The Accelerator does not contain a polymer for coating but contains a UV absorbing buffer which is matched to work with the Intiator Solution.

17. I am using CElixirOA™ very successfully except I am getting a “staircase” profile in my e-gram. What can I do to eliminate this? [top]
A staircase profile in an electropherogram, usually results from the non equivalence between inlet and outlet buffer composition. The easy solution is to replace all solutions at the same time. If this does not solve your problem, sometimes, a new capillary is the solution to this problem.

18. Can I use CElixirOA™ for the analysis of Cyanide? [top]
We have not been successful with Cyanide using any of the CElixirOA products. Using pH 12 buffers may be called for but we do not offer such a product at this time.

19. Can I use CElixirOA™ for the analysis of Flouride? [top]
Yes, our customers have been successful with Flouride using CElixirOA 5.4 product. However, please note that it may co-migrate with formiate. To increase chances of separation, a longer capillary and lower temperature will help.

20. How do you calculate the limit of detection for a CE method using CElixirOA™? [top]
I usually accomplish this with a calibration with 5 levels. Then I do a repeatability test on the level that will give an area close to 500 and calculate the mean, the standard deviation and the CV. I define so a Limit of quantification (LOQ) at CV=10%. The detection limit (LOD) is 1/3 of the limit of quantification.

21. I am analyzing wine, will the limit of detection (LOD) when I use CElixirOA™ allow for the proper analysis of common organic acids and anions in wine ? [top]
Yes, we usually work in ppm using corrected area with CElixirOA™. For calibration one should expect a R2 of 0.999 or more between 5 and 200ppm. Depending on injection of sample, LOD may be 1ppm and LOQ between 5 and 10ppm. This is usually enough for wine but it will always depend on your own requirements.

22. Can I use CElixirOA™ for the analysis of Bromide? [top]
Yes, our customers have been successful with Bromide using CElixirOA 5.4 product. However, please note that it may co-migrate with chloride. However, to increase resolution, you can use a longer capillary and a lower temperature. We suggest 15C.

23. What are the concentrations of each component in the 3 different anions test mixtures? [top]
We do not report the concentrations. These test mixtures are designed as an economic aid in method development and for checking your CE methods for organic acids and anions while in use. Each mixture’s components are listed below with migration times (75um x 60cm capillaries) at 30kV and peak areas under standard kit conditions. These test mixtures are designed to measure relative migration times when used with our CElixirOA™ kits.

It is important to note that these kits are not designed as standards and should not be used to calibrate your instrument or for quantitation.

CElixirOA 5.4
Name	Migration	Area (230nm)
Cl	2.829	3842
N3	3.325	1507
Formic (C1)	3.608	4326
Succinic	4.346	3639
Acetic (C2)	4.804	5321
Propionic(C3)	5.392	5108
Butyric(C4)	5.737	5126
Valeric(C5)	6.033	4386
Caproic(C6)	6.300	4241
Octanoic(C8)	6.767	3924

CElixirOA 2.5
Name	Migration	Area (200nm)
BR	2.267	8315
Maleic	3.592	7497
Tosylate	3.825	11786
Fumaric	5.521	6985
Mandelic	6.500	14522
Benzoic	7.525	30120

CElixirOA 8.2
Name	Migration	Area (230nm)
Formic(C1)	3.483	6218
Carbonic	4.013	Varies
Acetic(C2)	4.267	9090
Propionic(C3)	4.650	10275
Butyric(C4)	4.963	11668
Pentanoic(C5)	5.183	12518
Hexanoic(C6)	5.379	13012
Heptanoic(C7)	5.558	12809
Octanoic(C8)	5.721	15073
Nananoic(C9)	5.883	16034
Decanoic(C10)	6.042	16546
Dodecnanoic(C12)	6.383	13590

24. What is the best solvent to use as diluent with CElixirOA™? [top]
All situations are always unique but generally speaking, water is the best diluent to use. Not buffers.

25. I have great separation with CElixirOA™ but I would like to sharpen my peaks a little. What do you suggest? [top]
Methane-sulfonic acid or HCL can be used to sharpen peaks with CElixirOA™.

26. My migration times correlate very well with the migration time data posted on your website for the first 4 anions of the test mixture. However the last 6 migrate increasingly longer than what is posted. Is this normal? I used a 60cm capillary followed by the conditioning directions and ran the method. What do you suggest? [top]
I think the difference is most likely related to the capillary lengths. Normally we don't care too much about the difference in migration times because a 10% difference is normally considered acceptable. If one measures precisely the capillary length at 60.2cm you find with 50 runs a mean migration time (cv less 0.3%) listed below:

Cl 2.724min
N3 3.175min
Formic 3.447min
Succinic 4.115min
Acetic 4.536min
Propionic 5.072
Butyric 5.390min
Valeric 5.662min
Caproic 5.909min
Octanoic 6.336min