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GAINING EFFICIENCY UTILIZING “NEW” ANALYTICAL TECHNOLOGIES Dave Johnson – Laboratory Supervisor Muskegon County The Hach LDO Meter LDO = 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 Gunter ATP Program Coordinator USEPA Region 5 77 W. Jackson Blvd., WC-15J Chicago, IL 60604 (312) 353-9076 [email protected] 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 [email protected] 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 Disposable Plasticware Micro Dist® Apparatus Appartus Description A heating block that can distill Total Cyanide, Ammonia, Total Sulfide, and Total Phenolics with disposable plasticware. 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.