How do you find the concentrations of the Blank and Working Standards 1-3? Conce

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How do you find the concentrations of the Blank and Working Standards 1-3?

Concentration of Stock Standard Solution (Stock SS): 100 mu g/mL Concentration of Stock Internal Standard Solution (Stock ISS): 100 mu g/mL Working Standards: The Blank Solution was prepared by adding 250 mu L of the Stock ISS into a glass vial containing 4.75 mL of methanol, the diluent. Shake to mix well. Working Standard Solution #1 was prepared by adding 100 mu L of the Stock S5 and 250 mu L of the Stock ISS into a glass vial containing 4.65 mL of methanol. Shake to mix well. Working Standard Solution #2 was prepared by adding 250 mu L of the Stock S5 and 250 mu L of the Stock ISS into a glass vial containing 4.5 mL of methanol. Shake to mix well. Working Standard Solution #3 was prepared by adding 500 mu L of the Stock S5 and 250 mu L of the Stock ISS into a glass vial containing 4.25 mL of methanol. Shake to mix well. The submitted Test Samples were prepared by taking 100 mu L of the solution and diluting it to 5 mL with methanol. Then, these prepared Test Sample Solutions were diluted 100X by adding 50 mu L to 5 mL of methanol. The solutions were run in duplicate.

Explanation / Answer

a) The concentration of stock ISS is 100 micro gram/ ml ,so in 250 microitre it will be 25 microgram and it will be in total volume of 5ml.So ,the concentrstion 0f ISS is 25×1000/5×1000 = 5 mg/litre.

b)ISS amount is 25 microgram as calculated above and it is total volume of 5ml ( .1 ml + .25ml + 4.65ml ) Therefore ISS concentration is 5mg /litre

Stock SS concentration is 100 micro gram / ml. So , in 100 micro litre i.e 0.1ml the amount is 10microlitre and it will be in the total volume of 5ml ,So the SS concentration is 10×1000/5×1000 = 2mg/litre

c)ISS concentration is 5 mg litre as calculated above .

SS amount in 250 micro litre is 25 micro gram and this amount is in the total volume of 5ml , so the concentrayion is 25×1000/5×1000 = 5 mg/litre.

d) ISS contration is same as calculated and it is 5mg/litre

500 microlitre of SS contain 50 micro gram of SS and it is in total volume of 5 ml, so the concentration of SS is 50×1000/5×1000 = 10 mg/ litre

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