High Salinity TOC

Seawater and Brine are not easy martrixies to analyze for TOC and DOC. Thankfully you'll read this article and be fully prepared. 

Inorganic halides in samples compete with the organics in persulfate thus requiring more persulfate for complete oxidation. 

The two ways to tackle this problem are; increase the amount of persulfate that comes in contact with the sample and/or increase the concentration of persulfate. Unfortunately, by doing this background or reagent blanks are elevated. 

A simple solution to keep the persulfate from adding too much background is to boil and sparge your persulfate. 

Another problem with seawater and brine samples is incomplete oxidation and high %RSD. Poor reproducibility could be as simple as increasing the react time during heating at 96-99 degrees with acid and persulfate present. Typical times for drinking water samples range from 30 seconds to 2 minutes, whereas high salinity samples may need anywhere from 4 to 10 minutes of digestion. Don't be afraid to set up several different methods with various timed reactions to get consistent and accurate carbon dioxide values. 

Lastly and most importantly, is when analyzing high salinity samples don't forget to protect the instrument from the halides being produced. Add a halide scrubber to protect your NDIR detector and change frequently. 

The Salesman's Maverick: The Service Engineer

How to treat your most important resource. 

Stroke their ego. 

Do this in front if others. What do you care? You're making the commission he isn't.  The more they feel like the brains behind the operation the better help they can provide. 

I'm not suggesting that you let the service engineer take over the flow of the engagement, but make sure they feel as though they are integral part of the process. 

Treat to things you can expense but they can't.  

Golf, fancy meals, etc. 

Make sure YOU always pay.  Even if they are your senior or it comes out of the same company bucket. It shows you are taking care if them.  It could be as simple as one less receipt for them to expense.

Ask for their input.  Even if you already know the answer, but especially if you don't.  You don't want bombard them with emails to where they think you're incompetent but make sure they think they are an editor to your masterpiece that is a sale. CC others including their immediate manager on occasion so they get higher recognition.  

NEVER throw them under the bus! You can mend relationships either with the customer or with other coworkers, but you'll need to make sure the customer has complete confidence in the service well after the sale. Service is a sink or swim endeavor.  Great service will always help with the next sale and if there is some residual tension left in the air, the sales rep can always return afterwards to smooth things over.  My personal favorites are goodies; pens, mouse pads, food, or even some cheap consumables.

Take care of your Service Engineer and they'll take care of you.

Grassy Peaks

Sounds nice, but this is not a good thing. In this picture for Total Cyanide by UV digestion and amperometric analysis there are several things to check to solve this issue.

In order of cost, ease, and probability. 

1. Fresh reagents. Especially the NaOH. Since the sodium hydroxide flows directly over the membrane to the amp flow cell, any degradation will directly affect your results.
2. New membrane. Along the same idea, the membrane is critical for a stable baseline and sharp peaks.
3. When time permits, allow the system to flush.  Letting the reagents flow through the flow cell will settle the baseline and allow the amp cell to stabilize.  I'll even set the pump to 5% and allow to run overnight. 
4. Reference Electrode. Thankfully these are extremely easy and cheap to service and replace. Although it is recommended to change these every 6 months, I find they last a lot longer.
5. New pump tubing.  Replace the colored tygon tubing that lays over the peristaltic pump and remember the smallest ORN/BLU platen needs to be a slightly tighter than all the rest of the lines.   
6. Polish working electrode. Cleaning this surface will allow for a greater sensitivity especially if the silver electrode is fairly oxidized. Gently scrub with polishing compound but in a pinch you can use a dap of toothpaste. 
7. Replace Amp wires (A002299).  These three wires transmit the signal to the detector much like a volt meter.  
8. Replace Teflon digestion coil or at least try bypassing the UV digester all together to see if peaks improve.  

I describe the steps above to show the process upon which I followed to eliminate all possibilities for the peaks I am showing below.  Unfortunately, these were all unsuccessful due to the instrument being moved several times and some electronic damage occurred.  This was only fixed by replacing a board inside the chassis, but the process is the essential for diagnosis. 

TOP 10 WAYS TO REMOVE BUBBLES IN A FLOW CELL

ACA flow analyzer version of the Top 10 List.

10.    Flick the waste line.

9.      Pinch and release the waste line.

8.      If there is no back pressure coil (A001309) try adding one.   

7.      Push "Max Cal" on the pump. 

6.      Use syringe to force DI water and surfactant mixture through flow cell. 

5.      Add debubbler.  

4.      Add some surfactant to the carrier or first reagent. 

3.      Degas reagents.  

2.      Yell at it !!!!

and the number 1 way to get rid of bubbles inside a flow cell...

1.      Rebuild flow cell with new quartz windows (A002927) and o-rings (A000689).