This page is intended for students and others who may be new to research and inexperienced in preparing solutions.

CONTENTS:

• PREPARATION OF 1M STOCK SOLUTIONS
• DETERMINING GRAMS/LITER FINAL (PREP. WITHOUT STOCK SOLUTIONS)
• EXAMPLE: GRAMS/LITER CALC. FOR "MBL" ASW (PREP. WITHOUT STOCKS)

FOR 1M STOCK SOLUTION:

1. Check reagent bottle for chemical name, formula and formula weight, water of hydration, etc. to be sure that you have the correct ingredient.
   Note that water of hydration (e.g., formula.H₂O = monohydrate; formula.6H₂O = hexahydrate, etc.) can differ for a given salt, and changes the formula weight (see Appendix 2: Formula Weights).
2. FOLLOW ALL SAFETY PRECAUTIONS INDICATED ON REAGENT BOTTLE AND ON THE MATERIAL (CHEMICAL) SAFETY DATA SHEETS FOR THAT REAGENT.
3. For 1 liter of 1M solution: weigh amount in grams = formula weight (FW; from bottle or Appendix 2); dissolve in reagent-grade water to 1 liter total volume.

   Example: for 1 liter of 1M NaCl, dissolve 58.44g NaCl in less than1 liter and bring to 1 liter total volume.

4. For smaller volumes of 1M solution: determine volume ratio = ml volume desired/1000ml; multiply formula weight in grams x volume ratio; weigh that amount and dissolve to volume desired.

   Example: for 250 ml of1M NaCl, volume ratio = 250ml/1000ml = 1/4. 58.44g x 1/4 = 14.61g; dissolve 14.61g NaCl in less than 250 ml, and bring to 250ml total vol.

DETERMINING GRAMS PER LITER FOR EACH INGREDIENT IN THE FINAL SOLUTION WITHOUT USING STOCKS:

1. Check reagent bottle for chemical name, formula and formula weight, water of hydration, etc. to be sure that you have the correct ingredient (see Appendix 2: Formula Weights).
2. FOLLOW ALL SAFETY PRECAUTIONS INDICATED ON REAGENT BOTTLE AND ON THE MATERIAL (CHEMICAL) SAFETY DATA SHEETS FOR THAT REAGENT.
3. Obtain the millimolar concentrations for each ingredient from the Compendia Tables.
4. For each ingredient, multiply the millimolar concentration by 0.001 (i.e., 1/1000) to obtain the molar concentration.
5. For each, multiply molar concentration x formula weight to determine grams per liter final solution.
6. See Example below

EXAMPLE: CALCULATION OF GRAMS PER LITER FOR EACH INGREDIENT IN "MBL" ASW (ASW#1) WITHOUT USING STOCKS.

THE LAST COLUMN SHOWS THE AMOUNT TO WEIGH OUT AND DISSOLVE IN 1 LITER FINAL TOTAL VOLUME (e.g., 24.72 grams NaCl).

ASW# ---> Ingredients Available	#1: "MBL" formula, mM	Molar Conc. (M = mM x 1/1000)	Formula Weight (FW)	Grams/Liter (= M x FW)
NaCl	423.00	0.423	58.44	24.72
KCl	9.00	0.009	74.56	0.67
CaCl2.2H2O - or - CaCl2 (anhydrous)	9.27	0.00927	147.02 - or - 110.99	1.36 - or - 1.03
MgCl2.6H2O - or - MgCl2 (anhydrous)	22.94	0.02294	203.31 - or - 95.22	4.66 - or - 2.18
MgSO4.7H2O - or - MgSO4 (anhydrous)	25.50	0.0255	246.50 - or - 120.39	6.29 - or - 3.07
*NaHCO3	2.14	0.00214	84.01	0.18
H2O	to 1L	to 1L	to 1L	to 1L

* Add NaHCO₃ last.

CONTRIBUTORS:

C. Derby, Georgia State Univ.W. Eckberg, Howard Univ.R. Josephson, Univ. Cal.E. Kravitz, Harvard Univ.S. Pierce, Univ. MarylandD. Stokes, Emory Univ.

TECHNICAL ASSISTANCE:

A. Ellerin, Hunter Coll.D. Remsen, MBL