Why Solvent Filter/Degassers Matter?

Why change another Mobile Phase or new column, Got a noisy baselines.

Why Solvent Filter/Degassers Matters? ------ is a high-efficiency in-line system that is designed to remove dissolved gases from a solvent, then the mobile phase is withdrawn from the solvent reservoir and the degassed liquid is delivered to the pump.

• Degas eluents as particulates are removed
• Eliminate spurious peaks caused by outgassing in detectors
• Eliminate pump downtime caused by air locks and particulates in check valves
• Decrease piston wear; increase column life
• Filter safety into plastic-coated or heavy-walled solvent reservoirs

If the on-line degassers work 120% well, then need to clean/replace the Solvent Filter.

However, Do you still remember how to clean that?

Oh......Now I recalled some tough experiences in 3-years-Yellow Jackets Life. At 2005, made "a big mistake"-- put the Solvent Filter in the Ultra- Sonicator with MeOH. The Agilent Solvent Filter is made of glass, then the porous structure on the glass was damaged.

What solvents to be used to flush the HPLC lines to remove contaminants?

For "Dirty Analyst" --- A**P**/ Cin** *-- At least 27 different ingredients in them.

So Question is: What solvents to be used to flush the HPLC lines to remove contaminants?

My Answer is: Prepare solvent mixture consists of IPA and water, 50% each will effectively clean contaminations in the solvent tubes, capillaries, flow cells etc… in an HPLC system. Water will clean salts and other possible contaminants and IPA will clean both polar and non polar possible contaminants. Or just bypass the column with a tubing, then Using a low flow rate of 0.5 ml/min, flush the entire HPLC system for couple of hours to remove any contaminations. Or can also keep the flushing for overnight after preparing enough solvent mixture.

Go Home have a good resting, then when come back at early morning, A new trouble-free HPLC system is ready to go.

How to select buffers for my HPLC Separations?

How to select buffers for my HPLC separations?

Buffer Selection

Buffer	pKa	pH Range	UV Cutoff (A > 0.5)
Trifluoroacetic acid (TFA)	<<>	1.5-2.5	210 nm (0.1%)
KH2PO4/Phosphoric Acid	2.12	1.1-3.1	<200>
Tri-K-Citrate/hydrochloric acid 1	3.06	2.1-4.1	230 nm (10mM)
Potassium Formate/formic acid	3.8	2.8-4.8	210 nm (10 mM)
Tri-K-Citrate/hydrochloric acid 2	4.7	3.7-5.7	230 nm (10mM)
Potassium acetate/acetic acid	4.8	3.8-5.8	210 nm (10mM)
Tri-K-Citrate/hydrochloric acid 3	5.4	4.4-6.4	230 nm (10mM)
Ammonium formate	3.8 9.2	2.8-4.8 8.2-10.2	(50 mM)
Bis-tris propane� HCI/Bis-tris propane	6.8	5.8-7.8	215 nm (10mM)
Ammonium acetate	4.8 9.2	3.8-5.8 8.2-10.2	(50 mM)
KH2PO4/ K2PO4/	7.21	6.2-8.2	<>
Tris� HCI/Tris	8.3	7.3-9.3	205 nm (10 mM)
Bis-tris propane� HCI/Bis-tris propane	9.0	8.0-10.0	225 nm (10mM)
Ammonium hydroxide./ammonia	9.2	8.2-10.2	200 nm (10mM)
Borate (H3BO3/Na2B4O7 10 H2O	9.24	8.2-10.2
Glycine� HCI/glycine	9.8	8.8-10.8
1-methylpiperidine� HCI/1-methylpiperidine	10.1	9.1-11.1	215 nm (10 mM)
Diethylamine HCI/diethylamine	10.5	9.5-11.5
Triethylamine HCI/triethylamine	11.0	10.0-12.0	<>
Pyrollidine HCI/pyrollidine	11.3	10.3-12.3

PS: 0.05 M or 0.01 M is suitable for current assay requirement.

Pesticides 1,2-ethylene dibromide (EDB) and 1,2-dibromo-3-chloropropane (DMCP)

Pesticides Analysis of 1,2-ethylene dibromide (EDB) and 1,2-dibromo-3-chloropropane (DMCP) by (Agilent 6890 Micro-ECDs) after microextraction with hexane in acc ordance with U.S. EPA method 504.

Relative standard deviation (% RSD) for the entire method was less than 7% over a concentration range greater than two orders of magnitude with method detection limits of 0.003 ug/L or lower. So Nice!

Assay Details:
Inj. Vol.: 2-mL splitless injection Inlet Split/splitless; 200 °C, pulsed splitless mode (20 psi for 1 min)
Carrier Helium: 6 psi (40 °C); 3.5 mL/min constant flow.
Column: (A) 30 m, 0.53-mm id, 0.8-mm film DB-608, an equivalent of HP-608. (B) 30 m, 0.53-mm id, 1.0-mm film RTX-1701, an equivalent of HP-PAS 1701.
Oven Temp: 40 °C (4 min); 10 °C/min to 240 °C;
Detector: 330 °C.
Makeup Gas: nitrogen, constant column and makeup flow (60 mL/min)

Pesticides, EPA Methods, GC-ECD

Wish one month later, will have a new Toy in the Lab --- Micro-ECD.
Agilent 6890 Micro-ECD: G1530A Option 231, G1540N Option 231,G2397A .


(1)666, DDT: Organochlorine Pesticides, EPA Method 508 AND EPA Method 525.2 (2) ACEPHATE: EPA 40 CFR 180.108, CASRN 30560-19-1
(3)METHAMIDOPHOS:
(4)PARATHION :Organophosphorous Pesticides,EPA Method 8141A.

(5)PCNB: Pentachloronitrobenzene

In Grave Grief, China Mourns Quake Dead

I love my country "CHINA" SO MUCH, that is my Mother Land......

Actually, I don't like to put any non-Quality Control topic (HPLC,GC-MS/MS, ICP/AA, FT-IR) on my Chemistry Blog.
Now because I am a Chinese: I love my country "CHINA" SO MUCH, that is my mother land.

Glucosamine (C6H13NO5) : Glucosamine HCL/Glucosamine Sulfate

Glucosamine (C6H13NO5) is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids.

General HPLC Assay@ C18, 4.6x250 mm, 5um.
Mobile Phase: .1 % H3PO4, ACN
Detector Wavelength: 240 nm or 254 nm.

However, could not get a good chromatogram profile.

So low down the H3PO4 to .05%, use NaOH to adjust pH to 3.0, use the 190 wavelength........ Wow..... It works...
So here is a question: How to use the US Pharmacopoeia? 100% follow or made some adjust according your own specific lab facility ?

5973 Mass Spec failed to pump (1)

On Monday-May-09, found 5973 GC MSD’s failed to pump. Called the Agilent Tech Support, try to isolate the problem. (Bad Hivac Pump? Turbo Pump Over Speed? Leak At Gc Injection-Port? Leak At Mass-Spec Interface? Analyzer Door Thumb Screws To Tight? Or what else?May-10 ~ May12, final, came to a conclusion that the problem may lie in the leak on End-Cap of turbo-molecular pump. However, called the Customer Service of B** Edwards Turbomolecular Pumps , Charged 2-3**, then ordered another “refurbished kit, $5*” from internet.Disconnect the cable between GC and MSD

Take down the cover of EGM

Disconnect 5 wires

Remove the stable screw on the EGM

Pull out the EGM gently

Note: An***, Call me if have any problem, Best

High Pressure Error Message in the 1100 Series Liquid Chromatograph

High Pressure Error Message in the 1100 Series Liquid Chromatograph

1. Ensure that the upper pressure limit in the method is set to a value suitable for the analysis.

2. Disconnect the column and check pressure.

3. If high pressure is observed, even with the column removed, use the injector step commands to switch the injection valve to the bypass mode and monitor the pressure.

4. Open the purge valve. Note pressure. If pressure is high, replace the PTFE frit in the purge valve. If pressure is normal (less than 2 bar), close the purge valve and remove the capillary line from port 1 of the autosampler switching valve.

So, when do I need to change the frit in the Purge Valve of the Solvent Delivery Module (Pump)?

The most common way to determine if the Purge Valve frit needs to be replaced is by opening the Purge Valve and establishing a flow of 1 ml/min of Methanol. If the pressure is more than 7 BAR, the frit should be replaced.

What causes high pressure in my HPLC 1100?

What causes high pressure in my LC?

Probable Causes: 1. Blockage in PTFE frit in the purge valve.
2. Upper pressure limit is set too low.
3. Blockage past the damping unit.
Suggested Actions: 1. Open the purge valve. If the pressure is still high, replace the PTFE frit in the purge valve.
2. Look at the upper pressure limit setting in the software and make sure it is set to a value suitable for the analysis.
3. Check for blockages. (See below)
To Check for blockages, use the split system approach for troubleshooting: Remove the column, pre-column and pre-column filter, if they are installed. 1. If the pressure returns to normal, install a ZDV fitting in place of the column.
a. If the pressure is normal, the column, pre-column or filter was the source of the problem. Replace it.
b. If the pressure is high, look for blockage beyond the column (example: tubing to or from the detector).
2. If the pressure is still high after removing the column, check the tubing from the purge valve to the autosampler. If pressure is normal, use the injector step commands to switch the injection valve of the autosampler to the bypass mode.
a. If the pressure is normal, there is blockage in the autosampler. Check the needle, needle seat, needle seat capillary tubing, and rotor seal.
b. If the pressure is still high, analyze the tubing from the injection valve to the column inlet.