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Calculating a solution from mg/l to mg/kg based on a solid or liquid

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  • Calculating a solution from mg/l to mg/kg based on a solid or liquid

    If I make a calibration curve with HPLC. On the X ax is mg/l and on the Y-ax is the area.

    I dilute for example 0,5 gram solid or liquid in a 10 ml volumetric flask and make it up to volume with eluent. After some sample prep I inject the solution into the HPLC and found a area which has a concentration of 4 mg/l compared to the calibration curve. If we suggest that the slope goes through zero it makes a concentration of area unknown/slope.

    After this I want to calculate the concentration in mg/kg. Am I right if I do it in this way.

    Area/slope = concentration 4 mg/l absolute

    But the sample weighted was in 10 ml volumetric flask so 1000 ml/10 = 100

    4mg/l / 100 = 0.04 mg in 0,5 gram

    1000 gram / 0.5 gram = 2000

    2000*0.5 = 1000 mg/kg

    Is this the right way to do it?

  • #2
    Re: Calculating a solution from mg/l to mg/kg based on a solid or liquid

    Originally posted by Unregistered View Post
    If I make a calibration curve with HPLC. On the X ax is mg/l and on the Y-ax is the area.

    I dilute for example 0,5 gram solid or liquid in a 10 ml volumetric flask and make it up to volume with eluent. After some sample prep I inject the solution into the HPLC and found a area which has a concentration of 4 mg/l compared to the calibration curve. If we suggest that the slope goes through zero it makes a concentration of area unknown/slope.

    After this I want to calculate the concentration in mg/kg. Am I right if I do it in this way.

    Area/slope = concentration 4 mg/l absolute

    But the sample weighted was in 10 ml volumetric flask so 1000 ml/10 = 100

    4mg/l / 100 = 0.04 mg in 0,5 gram

    1000 gram / 0.5 gram = 2000

    2000*0.5 = 1000 mg/kg

    Is this the right way to do it?
    You end up with .04mg in 0.5g of sample, Yes.

    The amount of substance of interest in 1kg is 1000g/0.5g x 0.04mg = 80 mg/kg

    When you write it out, make sure you know what each number stands for.

    Comment


    • #3
      Re: Calculating a solution from mg/l to mg/kg based on a solid or liquid

      Originally posted by Mrs X View Post
      You end up with .04mg in 0.5g of sample, Yes.

      The amount of substance of interest in 1kg is 1000g/0.5g x 0.04mg = 80 mg/kg

      When you write it out, make sure you know what each number stands for.
      I was forgotten to write down the last step (1000 gram / 0.5 gram) x 0.04 mg = 80 mg/kg

      Thanks so I am calculating in the right way!

      Comment


      • #4
        Re: Calculating a solution from mg/l to mg/kg based on a solid or liquid

        yes definitely calculating it correctly! Keep up the good work.

        Comment


        • #5
          Re: Calculating a solution from mg/l to mg/kg based on a solid or liquid

          please help me to calculate the concentration lead in brain in microgram/gram if:

          o,4166 g brain was digest and the final volum is 10 ml. For determination concentration was injected 10 microliter and the lead concentration was 349,73 g/dl.
          what is the lead concentration in brain convert in microgram/g?

          Comment


          • #6
            Re: Calculating a solution from mg/l to mg/kg based on a solid or liquid

            Originally posted by Unregistered View Post
            please help me to calculate the concentration lead in brain in microgram/gram if:

            o,4166 g brain was digest and the final volum is 10 ml. For determination concentration was injected 10 microliter and the lead concentration was 349,73 g/dl.
            what is the lead concentration in brain convert in microgram/g?
            1 dL = 100 mL
            349.73 g/100 mL x 10 mL/0.4166 g = 83.95 g/g

            Provided your instrument reads concentration, the amount analyzed is not relevant, but you need the ratio of digester volume to sample mass.
            (Note I used US convention of decimal point, not comma.)

            Comment

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