Expedited Test Method Development for Emergency Response Clarence L. Haile, Ph.D., Raymond J. Erickson, and Joshua A. Cox REI Consultants, Inc. The Emergency Call • Can you test for [parameter] in [sample matrix]? • How fast, how many? • Example: – January 9, 2014 release of crude MCHM into Elk River near Charleston, WV – Can you test for MCHM in drinking water? – How fast, how many? First Considerations • Specific parameter identification • Approved test method available and is your lab accredited? – Yes. Start taking samples and assessing capacity – No – Start researching • Authentic standard material available? 4-Methylcyclohexylmethanol (MCHM) Sources for Physicochemical Properties • Material Safety Data Sheet • Chemical References, e.g. – Merck Index – CRC Handbook of Chemistry and Physics • Internet • Assumptions based on similar compounds MCHM Physicochemical Properties • • • • • C8H16O, MW= 128, CAS No. 34885-03-5 BP = ~180⁰C Solubility in water “appreciable” Solubility in solvents “unknown” Assumption for MCHM – similar to 2-ethylhexanol General Analytical Considerations for Organics • Amenable to chromatographic methods, gas or liquid methods – MCHM probably • Sensitivity to common GC detectors: FID, ECD, PID – MCHM likely best by FID • Amenable to mass spectrometry – MCHM could be problematic Approaches Considered for MCHM • Purge-Trap GC (VOA Approach) – Examples: EPA 602/8021,624/8260/524 – Polar compounds tend to carry over • Solvent Extraction and Gas Chromatography (SVOA Approach) – Examples: EPA 8015, 625/8270 – Concern for loss during extract concentration Evaluating the Best Options • Procure authentic standard – MCHM – assayed crude product provided by emergency response team • Evaluate most promising and expedient method options – MCHM example: Direct Aqueous Injection (DAI) GC/FID MCHM DAI GC/FID Method • GC/FID system same as used for Diesel Range Organic (DRO) by Method 8015 • Minor adjustments to temperature program, limit injection to 1.0 μL • Good chromatography and detection • Quantitation (calibration) range 0.5-90 ppm (mg/L) • >>Initiated emergency sample analysis • Bonus – Several GC systems available, short run time excellent capacity MCHM Chromatogram Continue to Evaluate Alternate Procedures To Lower PQL: VOA Approach • Purge-Trap GC/FID-PID (EPA 602) – Did note some tendency for carry over – Noted significant sensitivity to PID • Changed to amber sample containers Extraction/Concentration (SVO) Approaches • Separatory Funnel or CLLE Extraction followed by Extract Concentration – Examples: EPA Methods 3510 or 3520 – 1.0-L sample, extract 3x w/ 100 mL solvent, conc. to 1.0 mL 1000-fold conc. • Solid Phase Extraction – Example: EPA Method 3535A – 1.0-L sample, elute disk w/ 60 mL solvent, conc. to 1.0 mL 1000-fold conc. Micro Extraction • Examples: EPA Methods 8011 or 504.1 • 35-mL sample, extract w/ 2.0 mL = 17.5-fold conc. • Typical successful for – Compounds much more soluble in solvent than water – Relatively clean waters • Extraction solvent must be lighter than water Micro Extraction in Volumetric Flask • 100-mL extract with 1.0 mL hexane = 100-fold concentration • Add salt (NaCl) to enhance partitioning and extract recovery • Small neck of flask aids extract recovery • Added 2-ethylhexanol as extraction surrogate Volumetric Flask Micro Extraction and GC/FID • Used same GC/FID systems and parameters as DAI GC/FID method • Increased injection volume to 2.0 μL • Effectively 200-fold concentration • Quantitation range 1.8-230 ppb (μg/L) • Successfully analyzed nearly 3900 samples, so far Sometimes the Needs “Evolve” • MCHM spill example – additional parameters of concern came to light – PPH – Propylene glycol phenyl ether – DiPPH – Dipropylene glycol phenyl ether PPH and DiPPH? PPH DiPPH Physicochemical Properties Formula MW CAS BP Sol in Water PPH C9H12O2 152 770-35-4 241.2 15.1 g/L DiPPH C12H18O3 210 51730-94-0 280 30 g/L Application of MCHM Method for PPH and DiPPH? • Obtained authentic standards from original manufacturer • GC method modification – extend runtime for higher boiling point compounds • Microextraction method – modification not required MCHM, PPH, and DiPPH Chromatogram Critical Concentrations MCHM PPH DiPPH ppb (μg/L) Calibration Range Low High 1.8 230 1 260 4.8 241 MDL 0.32 0.75 0.72 General Outline for Emergency Response • Get all the facts – Specific parameter and matrix – Likely number of samples, duration, TAT • Check applicability of approved methods, accredited – If Yes proceed to test samples – If No start researching • Acquire authentic standard Emergency Method Research • Verify parameter identity • Obtain physicochemical properties • Develop method approaches – based on approved methods, where possible • Evaluate performance of best approach(es) – optimize as needed Emergency Method Research • Select the best performing method and proceed to test samples – Prioritize on achievable turnaround time and capacity – Maintain consistent method performance • May need to continue method refinement and/or evaluate alternatives simultaneously with sample analysis – Sometimes the needs evolve Emergency Method Quality Considerations • Emergency testing must be conducted within the framework of lab quality program – Defined Method Performance Criteria • Calibration, Blanks, Dups, LCS, Matrix Spikes • MDL study, Demonstration of capability – Documentation – SOP(s) • Emergency results are only useful if they are supported
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