UNDERSTANDING PARTS PER MILLION

PPM conversion values and serial dilutions : Ppm concentrations and percentages. Ppm to Molarity and Molarity to ppm. HOME Email Webmaster Related link 1000ppm AA Stds. PPM = parts per million PPM is a term used in chemistry to denote a very, very low concentration of a solution. One gram in 1000 ml is 1000 ppm and one thousandth of a gram (0.001g) in 1000 ml is one ppm. One thousanth of a gram is one milligram and 1000 ml is one liter, so that 1 ppm = 1 mg per liter = mg/Liter. PPM is derived from the fact that the density of water is taken as 1kg/L = 1,000,000 mg/L, and 1mg/L is 1mg/1,000,000mg or one part in one million. OBSERVE THE FOLLOWING UNITS 1 ppm = 1mg/l = 1ug /ml = 1000ug/L ppm = ug/g =ug/ml = ng/mg = pg/ug = 10 -6 ppm = mg/litres of water 1 gram pure element disolved in 1000ml = 1000 ppm PPB = Parts per billion = ug/L = ng/g = ng/ml = pg/mg = 10 -9 PARTS PER MILLION : CALCULATIONS Making up 1000 ppm solutions 1. From the pure metal : weigh out accurately 1.000g of metal, dissolve in 1 : 1 conc. nitric or hydrochloric acid, and make up to the mark in 1 liter volume deionised water. 2. From a salt of the metal : e.g. Make a 1000 ppm standard of Na using the salt NaCl. FW of salt = 58.44g. At. wt. of Na = 23 1g Na in relation to FW of salt = 58.44 / 23 = 2.542g. Hence, weigh out 2.542g NaCl and dissolve in 1 liter volume to make a 1000 ppm Na standard. 3. From an acidic radical of the salt : e.g. Make a 1000 ppm phosphate standard using the salt KH2PO4 FW of salt = 136.09 FW of radical PO4 = 95 1g PO4 in relation to FW of salt = 136.09 / 95 = 1.432g. Hence, weigh out 1.432g KH2PO4 and dissolve in 1 liter volume to make a 1000 ppm PO4 standard. Click this link for Atomic absorption standards Dilution Formula : C1V1 = C2V2 This equation applies to all dilution problems. C1 (initial conc) x V1 (initial volume) = C2 (final conc) x V2 (final volume) Example : What volume of 6.00 ppm solution must be used to give 4.00 liters of a 0.100 ppm solution? C1 = 6.00 ppm V1 = unknown C2 = 0.100 ppm V2 = 4 liters = 4000 mls V1 = (C2 x V2) / C1      = (0.100 X 4000) / 6.00      = 400 / 6.00 = 66.7 mls. This means that 66.7 mls of the 6.00ppm solution diluted to a final volume of 4 liters will give a concentration of 0.100 ppm. The Formula below can be used to calculate the the V1 component only. req is the value you want. req ppm x req vol -------------------------- = no of mls for req vol          stock Example : Make up 50 mls vol of 25 ppm from 100 ppm standard. 25 x 50 / 100 = 12.5 mls. i.e. 12.5 mls of 100 ppm in 50 ml volume will give a 25 ppm solution Serial dilutions Making up 10-1 M to 10-5 M solutions from a 1M stock solution. Pipette 10 ml of the 1M stock into a 100 ml volumetric flask and make up to the mark to give a 10-1 M soln. Now, pipette 10 ml of this 10-1 M soln. into another 100 ml flask and make up to the mark to give a 10-2 M soln. Pipette again, 10 ml of this 10-2 M soln. into yet another 100 ml flask and make up to mark to give a 10-3 M soln. Pipette a 10 ml of this 10-3 M soln. into another 100 ml flask and make up to mark to give a 10-4 M soln. And from this 10-4 M soln. pipette 10 ml into a 100 ml flask and make up to mark to give a final 10-5 M solution. ppm to Molarity Molarty to ppm You tube clips embedded Signature: Dhanlal De Lloyd, Chem. Dept, The University of The West Indies, St. Augustine campus The Republic of Trinidad and Tobago. Copyright: delloyd2000© All rights reserved.