J O U R N A L Research Drug Discovery Clinical Screening Liquid Scintillation Counting LSC in Practice Safer Cocktail Selection for Use With Potassium Chloride Problem: One of PerkinElmer’s field representatives requested help for a researcher currently using PerkinElmer cocktails that contained toluene and xylene. The researcher hoped to “skip” two generations of cocktails and move up to PerkinElmer’s newest, Ultima Gold™, line of cocktail. The researcher’s primary concern was compatibility of the cocktail and sample. The researcher’s sample consisted of 0.4 M potassium chloride. Discussion: We evaluated the sample loading capacities for several members of PerkinElmer’s Ultima Gold family of cocktails using 0.4 M potassium chloride at 20°C. The results of our testing are tabulated below: Cocktail Maximum Capacity (mL/10.0 mL cocktail) Maximum Capacity (mL/5.0 mL cocktail) Ultima Gold (part number 6013329) 1.5 mL 0.4 M KCl 0.75 mL 0.4 M KCl Ultima Gold MV (part number 6013159) 1.5 mL 0.4 M KCl 0.75 mL 0.4 M KCl Ultima Gold XR (part number 6013119) 6.0 mL 0.4 M KCl 3.0 mL 0.4 M KCl Ultima Gold LLT (part number 6013377) 6.0 mL 0.4 M KCl 3.0 mL 0.4 M KCl Recommendation: The results from Table 1 show that PerkinElmer’s Ultima Gold XR and Ultima Gold LLT are both highly suited for this researcher’s application. If the researcher is using an 8 mL vial, we recommend using 1.5 mL of 0.4 M KCl with 5.0 mL of Ultima Gold XR or Ultima Gold LLT. If a 6 mL vial is being used, then 1.5 mL of 0.4 M KCl may be added to 4.0 mL of cocktail. Worldwide Headquarters: PerkinElmer Life Sciences, Inc., 549 Albany Street, Boston, MA 02118-2512 USA (800) 551-2121 European Headquarters: PerkinElmer Life Sciences, Imperiastraat 8, B-1930 Zaventem Belgium Technical Support: in Europe: [email protected] in US and Rest of World: [email protected] Belgium: Tel: 0800 94 540 • France: Tel: 0800 90 77 62 • Netherlands: Tel: 0800 02 23 042 • Germany: Tel: 0800 1 81 00 32 • United Kingdom: Tel: 0800 89 60 46 Switzerland: Tel: 0800 55 50 27 • Italy: Tel: 800 79 03 10 • Sweden: Tel: 020 79 07 35 • Norway: Tel: 800 11 947 • Denmark: Tel: 80 88 3477 • Spain: Tel: 900 973 255 All trademarks or registered trademarks are the property of PerkinElmer Life Sciences, Inc. P11429 © 2002 PerkinElmer Life Sciences, Inc. www.perkinelmer.com/lifesciences B R I E F September 18, 1995