Perceptions #1

Perceptions, they can work to your favor, or sometimes the opposite.

It's actually quite scary, when people jump into conclusion without understanding the full story.

Or rather, believing only in what they want to hear.

If you criticize people's work, ask if you can do it better and faster.

When UPLC sensitivity dropped to 2-3 times

I once encountered a case whereby injecting the same amount of standard into 2 UPLCs side by side, the area for UPLC#2 is about 2 - 3 times smaller than UPLC#1.

Customer reported that their %RSD is good, but they aren't sure why the area is so much different.

Well... I was equally baffled too.

1. Performed a leak test and there was no leak from the sample syringe.
2. Lamp energy seems fine.
3. Guessed there could be a clogged somewhere in the needle or along the SM fluidics.
4. Since it was also due for PM, might as well start replacing the needful.

Then I found out.

Someone configured the volume syringe 100uL instead of the rightful 250uL.



Not sure whether to laugh or cry eh...

Frustrating people #1

Today I had a someone who kept firing shots at me when I suggest that her problems were likely due to her column.

She encountered accumulator over pressure and a noisy baseline.

Hey. I haven't even gone to the details of why your column is giving you these problems.

I was going to borrow her column to replicate the problem,

NO I CANNOT LEND YOU MY COLUMN, THIS IS THE ONLY COLUMN I HAVE AND I NEED TO USE IT. EVERYTIME AFTER YOU GUYS DID A PM OR A TROUBLESHOOTING AND THERE WOULD BE PROBLEMS WITH THE INSTRUMENTS!!! THIS COLUMN IS TOTALLY FINE ON ANOTHER INSTRUMENT. I'VE CHANGED THE CHECK VALVES ON THAT INSTRUMENT AND I AM STILL SEEING ACCUMULATOR OVER PRESSURE! (blahhhh)

Wow wow wow wait a minute.

(And wah lao - My point #1: why would check valves be related to accumulator over pressure.
Point #2: To defend myself, previous corrective actions were a new lamp and flow cell replaced just 2 weeks ago. These new problems were not related to previous corrective actions.)

Then onward, she kept switching topic incoherently between high pressure and noisy baseline.

Hello, can you focus on a problem one at a time?

And if I run a flow with water/ACN and I can achieve a low system pressure and a very flat baseline (beautiful!), it was pretty clear that her problem is due to that column...

Besides, she then acknowledged that she saw accumulator over pressure again on another instrument with the same column.

And she continues to insist that it's not the column.



I don't even...

Tribute to the late LKY

I had wanted to make my way to the parliament house and pay my last respect to the late LKY. But was very much plagued by work and too fatigued to combat the 10hr-long queue. Finally headed to Tampines community tribute center instead.

Thank you, MM Lee

The recent years I had grown to detest the PAP, because, of the obvious reasons.

For the excessive foreigners that flood our island, fighting for our jobs and suppressing our wages;
For the public transport that became too unbearable from the squeeze and subsequently the frequent breakdowns of trains;
For the poor control of public housing that drives purchase prices to the sky.
Not to mention LKY the dictator who silenced the oppositions; the 1987 marxist conspiracy; the unreliable Straits times which serves only as PAP's mouthpiece; the constant putting down of oppositions and accusations; the worship of expats and turning Singaporeans into 2nd citizens of our own country, so on and so forth.

My perception started to change when I headed to Shanghai for various job training last year. Training were mostly conducted in Mandarin, because the China trainees had poor grasp of English. It was especially tough for me, for I did not know the technical terms in that language.

But I felt blessed to be bilingual, and I was fortunate to survive the total 5 weeks.

The Chinese had a great wealth of knowledge which impresses me very much. However they aren't inclusive if you don't speak their language, so they won't share. Well, pretty much the same for the everywhere else in the world. Fortunately I could converse decently and blend into them.

Me surviving well in Shanghai

It then dawned on me that LKY had the vision to implement bilingual policy in the early days, how often had I taken it for granted. I knew for the longest time that we were basically connected to the East and the West. But to go out and experience it myself, it was an overwhelming feeling.

I am inadequate, as we all are.
But we are equipped with survival skills to carve our journeys in life.

Like Chiam put it, "His contributions to Singapore far outweighs the criticisms."

Thank you for building a nation of educated and bilingual people so our country can survive.
Thank you for building a safe and civilized country so we don't have to be afraid of walking in the night.
Thank you for the racial and religious harmony that we can accept and enjoy our cultural diversity.
And finally thank you, for giving us the confidence to go out to the world.

Why is there a negative dip in my HPLC chromatogram?

Because your solvent absorbs UV to some extent, too.

If you constantly see a negative dip, it may come from your sample, diluent, mobile phase, bottle, cap, glassware, column problems etc, that some compound is eluting out but does not absorb UV to the extent that your solvent does.

If there is a difference in composition between the injection solvent and mobile phase, your diluent (eg. water) could have a lower optical density than your mobile phase (eg. methanol) does. The negative dip will appear right before your sample is eluted.


*LC grade means that UV light absorbing impurities have been removed (not that the absolute purity is higher) and absorbance of specified wavelengths is kept within a specified range.

Lost prime

When your instrument prompts an error of a lost prime, it means pressure has dropped to below 25 psi for the last 50 cycles of plunger. Very often, gas bubbles interrupted the solvent path.


First, check that:

1. There is enough solvents in the bottles.
2. All solvent lines are properly connected and not drawing air into the system.
3. All solvents degassed and lines properly primed. It is more effective to prime each line at 100% for 5 min rather than 25/25/25/25 for A/B/C/D.


Other possible causes:

1. Solvent reservoir filters clogged.
2. Bacteria growth in the lines or inline filter and becomes clogged. May be able to clean out with 100% MeOH.
3. Primary inlet check valve failed. Ruby ball can get sticky over time esp if applications involve high ACN content. Ball gets stuck at the close position, so solvents cannot be delivered.


Passivating with 30% Phosphoric acid or 6N of Nitric acid not recommended.
This involves extreme cleaning, takes a lot of time, and unnecessary wearing of parts.

When sample energy is higher than reference energy

How is that possible?! So I thought perhaps,

1. the reference photodiode may be slightly off its position.
2. the beam splitter was giving problems.
3. reference diode deteriorate faster than sample diode.

But until I stripped the detector naked, it was because of...

this.

How did they even crack inside the detector in the first place?! Pretty amazing.