How to clean Isomist

Question

Hello Agilent community, 
 1. we have measured organic standard and samples diluted by kerosene with isomist (Agilent ICPOES 5800). Now we try to measure some methanol samples. Also with isomist. How can I clean the isomist properly? Kerosene and methanol are incompatible. Thanks a lot. 
 2. To measure the methanol samples, which standard should I order? Thank you! 
 Best regards 
 Sophia

Agilent · Accepted Answer

Hello sophia , thank for sharing this question. 
 One suggestion is to use an intermediary solvent in which kerosene and methanol are miscible. Some options are 1-butanol or maybe tert-butanol. Try the solubility before applying to the Isomist. If it does not work, you could try using an non-ionic detergent to clean out the kerosene, then rinse a lot with Type 1 water and then insert methanol. You should do this with the system disconnected from the torch, to avoid the tertiary aerosol reaching the plasma. 
 As for methanol samples, you should definitely go with the volatile solvent sample intro kit (0.8 mm ID torch , Isomist temp around -5&deg;C and peristaltic pumping at 8-10 RPM), otherwise you will likely extinguish the plasma, if introducing it directly. One option is to dilute the samples in HNO3 1% (maybe 10x), and use aqueous standards in your calibration curve. To avoid accuracy problems due to sample transportation, I recommend the use of internal standardization using Y at 5-10 ppm using a "Y" piece (maybe white/white for samples and orange/white tubing for the IS, with a double pass SC). Remember that diluting the samples 10x will increase your LOQ 10x, so evaluate carefully if this is a valid alternative to your routine. Diluting it 10x you may be able to run the methanol samples just as aqueous (without the need of Isomist and with the standard intro kit). 
 Hope this helps, 
 Rodolfo

Agilent · Answer

Hey sophia , 
 If you are going to directly introduce methanol, you can prepare your calibration curve using an ultrapure methanol as solvent and add the aqueous standards by weight, just like when you prepare standards for other organic samples, since methanol and water have different densities. 
 You can check this app note where methanol were analyzed by the 4200 MP-AES: https://www.agilent.com/cs/library/applications/5991-6469EN_4200_MP-AES_methanol.pdf 
 They used aqueous standards to prepare the analytical curve. 
 Best regards, Rodolfo

Agilent · Answer

Hey sophia , I am happy that the information is being useful! 
 As for the M15, since you have gasoline in it, I would try using ultrapure isooctane to dilute the samples. Recently I have performed a demonstration for naptha samples and this was the best approach to reduce the final mixture volatility. I believe you will achieve good results. Depending on the elements you are quantifying, you should take care to choose the proper isooctane to avoid high CPS in the blank solution. 
 The same recommendations for the sample intro system and operational conditions are valid, as you mentioned. As you have gasoline, maybe the use of Viton tubing is necessary. I would give it a shot and run with the Solvaflex tubing first (the yellow one). 
 Calibration curve in this case should be done with isooctane and organic standards, by mass, and you could dilute the samples 2x by mass. I would use Y as internal standard to correct transportation effects, and you can find it in organic form. Try using it around 5-10 ppm using a "T" piece or add the same amount in every solution (blank / standards / samples). 
 Best regards, Rodolfo

How to clean Isomist

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