GAINING EFFICIENCY UTILIZING “NEW”

ANALYTICAL TECHNOLOGIES

Dave Johnson – Laboratory Supervisor Muskegon County

The Hach LDO MeterLDO = Luminescent Dissolved Oxygen

Measuring DO - Current Techniques

Electrode Membrane DO Meter (EPA 360.1) Winkler Titration (EPA 360.2)

Winkler Titration

Interferences, positive and negative Not a field technique Short holding time (8 hours)

Electrode Membrane DO Meter The membrane cap filled with electrolyte

solution must be fitted "just right" Membrane can become fouled Hydrogen Sulfide gas reduces electrode

sensitivity Sample agitation (flowing water or stirring)

must accompany measurement to overcome erratic responses

Illustration used by permission of Dr. Cary B. Jackson of Hach Company

Advantages of the LDO

No more membrane caps and electrolyte solution to replace!!

No interferences No stirring or flow necessary No warm up time Better precision than other techniques

The Good News and the Bad News...

The Good News

USEPA Recommends the LDO meter for NPDES compliance monitoring

The next time the list of NPDES-approved methods is updated, the LDO method will be on the list for DO and BOD.

Each USEPA region may grant blanket approval for use of the LDO method for NPDES compliance reporting

The Bad News

Region 5 has not given blanket approval!

The Bottom Line

To use the LDO meter for NPDES compliance reporting, you have to jump through the hoops of a formal Alternative Test Procedure request (ATP).

Region 5 ATP Request Requirements

A letter of request Documentation of your Initial Demonstration

of Laboratory Capability A copy of your SOP Your NPDES Permit Number (or the NPDES

Permit Numbers for All Your Clients that would be affected)

ATP Request Requirements

Send an ATP request to:

Kenneth GunterATP Program CoordinatorUSEPA Region 577 W. Jackson Blvd., WC-15JChicago, IL 60604

(312) 353-9076gunter.kenneth@epa.gov

Method Information

Hach Method 10360 (it was almost EPA 360.3) ASTM D888-05, Method C Caveat: ASTM D888-92 ≠ ASTM D888-05

Additional Disadvantages

Cost is $1100 - $1250, comparable to a high-end electrode membrane meter.

Hach Method 10360 has more stringent QC. Check standards must be analyzed before and after a run which ties this method more closely to the lab.

Preweighed Filters For Solids

Old vs. New

Advantages / Disadvantages

Advantages of pre-weighed Filters No prep time for filters Elimination of the large background mass of the gooch

crucible 4.7 cm filters have 4 times more surface area than 2.4 cm

filters (more surface area = faster filtrations)

Disadvantage Costs approximately 3-4 times more than a 2.4 cm filter

Discrete Analyzers Automating Colorimetric Tests

Manufacturers Lachat OI Analytical Seal Analytical Systea Scientific Thermo

Scientific Westco et al.

Continuous Flow Analyzers (Old School)

2007: 50th Anniversary of the Invention of Continuous Flow Analyzers (1957 - The continuous flow analyzer developed by Technicon)

Problems with Continuous Flow Analyzers Plumbing problems High concentration samples cause carry-over Difficult to do a color blank

Discrete Analyzers (New School)

Faster than continuous flow analyzers

Color blanks are no problem

The potential for carry-over is greatly reduced

Plumbing problems vanish

Discrete Analyzers “Wave of the Future” for colorimetric analyses Potential Problems/Issues

Software – you have to use what you get, not always user friendly

Purchased reagents are not always reliable Random air bubbles can cause false positives or high bias The high cost of consumables Achieving acceptable detection limits Methods can be difficult to develop Analyzers may not analyze nitrate-nitrite by cadmium

reduction.

BOTTOM LINE – KNOW WHAT YOU ARE BUYING

Discrete Analyzers Questions to Ask your Sales Representative What are the prices of consumables?

What are your guaranteed detection limits?

What methods can you have developed during installation before you leave?

What happens if your guarantees cannot be met?

What references can you give me?

BOTTOM LINE – BE VERY THOUROUGH WHEN WRITING INSTRUMENT SPECIFICATIONS

Discrete Analyzers Questions to Ask Your References

Are all methods working? How long did it take to develop them?

Have any methods/analyses given you trouble? Do you have problems with reproducibility? Did you purchase your discrete analyzer to replace a

continuous flow analyzer? Has it? Is the software user friendly? What features do you

like / dislike? Does your instrument meet the detection limits

required for your applications? Are reagents purchased from the manufacturer

reliable? Is tech support helpful and responsive?

Discrete Analyzer Nitrate-Nitrite Analysis Tips

Hydrazine Reduction (SM 4500-NO3- H)

Approved for NPDES Not approved for drinking water

Nitrate Reductase Method Uses an enzyme for reducing nitrate to nitrite Equal in performance to cadmium reduction Method developed using Discrete Analyzers Eliminates exposure to hydrazine sulfate and cadmium Learn more at www.nitrate.com/nar-nam1.htm Not approved for NPDES or Drinking Water (ATP necessary)

ATPs For Drinking Water ATPs are possible for drinking water. Send these ATP

requests to:Patrick Churilla

Quality Assurance/Laboratory Certification

USEPA Region 5

77 W. Jackson Blvd., WG-15J

Chicago, IL 60604

(312) 353-6175

churilla.patrick@epa.gov

Digestion Blocks with Disposable Plasticware

Just Say No

Digestion Blocks Advantages / Disadvantages

Advantages Cleaner digestions Uniform heating Time saved in cleaning glassware The vessels are calibrated for volume so that aliquots can be

measured directly in the vessels. No transfer of digestates to a new vessel after digestion Any digestion performed on a hot plate or in a water bath

can be adapted for the digestion block.

Disadvantages Initial Cost of Digestion Block ≤ $4000 Cost of consumables, approximately 35¢ - 40¢ per digestion

Distillation Blocks with DisposablePlasticware

Micro Dist® Apparatus Appartus Description

A heating block that can distill Total Cyanide, Ammonia, Total Sulfide, and Total Phenolics with disposable plastic-ware.

Requires only 6 ml of sample for distillation and a proportionate amount of distillation reagents.

The sample is sealed in the bottom of the tube. A trapping solution is in the upper part of the tube. A hydrophobic membrane separates the trapping solution from the sample. The Cyanide passes through the membrane and into the trapping solution.

The Cyanide passes through the membrane and into the trapping solution but the water matrix does not.

Initial Cost ≤ $4000

Micro Dist® Advantages Less reagents used. The amount of reagent to distill

one sample with a regular distillation unit will do 8 samples on the MICRO DIST®.

No purge gas flow rate to optimize each time. Set-up time and distillation time are markedly less. (30

minute distillation for Cyanide, Ammonia, and Sulfide. Phenolics require 90 minutes.)

Able to distill 21 samples at a time. No fragile glassware to clean up. Very accurate and repeatable.

Micro Dist® Disadvantages The consumables are a major expense: Approximately $6 to $7

dollars per distillation tube = ~$140 in plastic consumables every time you distill a full load of 21 samples.

Samples containing organics may cause the membrane to blow out. The only recourse is to distill at a dilution (elevated detection limit).

Total CN is being replaced by available CN, which requires different instrumentation.

Limited amount of distillate means you’ll need a Discrete Analyzer or Continuous Flow Analyzer for the analysis.

Good News / Bad News

The Micro Dist® is approved for NPDES and Drinking Water monitoring of Total Cyanide. (QuikChem Method 10-204-00-1-X)

It is NOT approved for monitoring of Total Phenolics or Ammonia

In Closing…

Don’t be afraid of seeking an Alternative Test Procedure (ATP)!

Don’t be afraid of trying something new (but check your references!!)

Don’t be afraid of asking for help.