Description: AQUAfast total nitrogen LR digestion tubes. Format: Digestion Tube. For Use With (Equipment): Orion AquaMate Vis and UV-Vis Spectrophotometers, Orion AQUAfast AQ3700 Colorimeter. Includes: Set of 5: 50 TN Hydroxide LR Digestion Tubes, 50 Persulfate Reagent Powder Packs, 50 TN Reagent A Powder Packs, 50 TN Reagent B Powder Packs, 50 TN Acid LR/HR Reaction Tubes.