WP Total Hardness Back Catalog number: 54597 Manufacturer: ABSOLUTE STANDARDS Availability: In the manufacturer's stock Price on request - + Recommended 93242 Oak Aroma Standard Price on request 11681.12-100-IO 3,3',5-Trichlorobiphenyl ,100 µg/mL,isooctane,1mL, Price on request 23112 EPA Method 8260B Surrogate Standard Price on request