Problem Discussion From our experience, there are three possible cocktails that would be best suited for this application. These cocktails are Hionic-Fluor™ (part number 6013319), Opti-Fluor® (part number 6013199) and Emulsifier-Safe™/ Poly-Fluor™ (part number 6013389). We tested the three cocktails with mid-ocean sea water by adding 100 µL to 5.0 mL of cocktail. Note: The presence of the 2 mM sodium bicarbonate in sea water will not affect the overall sample acceptance characteristics of the cocktails. After adding the sample, we added 0.2 mL (200 µL) of 0.1 N sodium hydroxide to ensure that the pH was greater than 8 which would prevent “gassing.” With Hionic-Fluor, a clear stable mixture was formed at 20 °C. With Emulsifier- Safe, a slightly opalescent mixture was formed at 20 °C. With Opti-Fluor, a slightly hazy mixture formed at first, but on standing for 15 minutes at 20 °C, a clear mixture resulted. Recommendation From the obtained test results, Hionic-Fluor or OptiFluor would be best for the researcher’s system. Because 14C, a high energy beta emitter, is the isotope of interest and the sample is relatively small, there will be virtually no difference in counting efficiency between the two cocktails. The use of either of these two cocktails with the added 0.1 N sodium hydroxide ensures against the potential problem of “gassing.” However, we do recommend the use of Opti-Fluor since it is a safer cocktail. PerkinElmer, Inc. 940 Winter Street Waltham, MA 02451 USA Phone: (800) 762-4000 or (+1) 203-925-4602 www.perkinelmer.com For a complete listing of our global offices, visit www.perkinelmer.com/lasoffices ©2007 PerkinElmer, Inc. All rights reserved. The PerkinElmer logo and design are registered trademarks of PerkinElmer, Inc. Emulsifier-Safe, Hionic-Fluor and Poly-Fluor are trademarks and Opti-Fluor is a registered trademark of PerkinElmer, Inc. or its subsidiaries, in the United States and other countries. All other trademarks not owned by PerkinElmer, Inc. or its subsidiaries that are depicted herein are the property of their respective owners. PerkinElmer reserves the right to change this document at any time without notice and disclaims liability for editorial, pictorial or typographical errors. 007902_13 N O T E A researcher contacted us to learn how to “bind” a 100 µL NaH14CO3 (sodium bicarbonate) and sea water sample to prevent loss of activity due to gaseous release during sample preparation. A P P L I C A T I O N L S C C O C K TA I L S LSC in Practice Preventing Gaseous Release with Sodium Bicarbonate Samples