ppm and mcg

Table of Content

• Introduction and outcome
• % (Percentage)
• ppm
• mcg
• Relation between % and ppm
• Relation between ppm, mg and litre (L) and Kg
• What is the difference between mcg and ppm?
• Conclusion
• FAQs

Introduction and outcome; ppm, mcg and % (percentage)

ppm, mcg and % are the unit of measurements and these terms are highly used by both synthetic chemist and Analytical chemist during sample preparation.

Neither Analytical Research work nor Quality control analysis work is possible without knowing %, ppm and mcg.Especially the chemists have a lot of confusion related to these terms. That is why I decided to share my skill-based knowledge on this topic to clarify all doubts related to these terms.

This post will clarify all your doubts related to %, ppm and mcg and enable you to answer many questions related these topics; such as:

• What is ppm?
• What is mcg?
• What is relationship between ppm, mcg, litre and Kg?
• What are µg, µg/ml and %.?
• How ppm is converted into %?
• How % is converted into ppm?
• What is the difference between ppm and mcg/ml
• Where is ppm used and where is mcg used?

% (Percentage)

% stands for parts per 100 or out of 100 or out of 10²

ppm

ppm stands for parts Million or out of 1000000 or out of 10⁶. This is a mode of expressing the presence of a substance ( at a very low concentration) in the main substance such as the presence of an impurity in a drug substance. It is a dimensionless quantity. Examples: 

• The limit of toluene in an API is 890 ppm,  which means the allowable limit of toluene per kg or per 10⁶mg or 1000000 mg of API is 890 mg.
• The limit of Ethanol in an API  is 5000 ppm,  which means the allowable limit of Ethanol per kg or per 10⁶ mg or 1000000 mg of API is 5000 mg.
• The limit of Lead in an API is 10 ppm,  which means the allowable limit of Lead per kg or per 10⁶ mg or 1000000 mg of API is 10 mg.
• The limit of Calcium in Soil is 540 ppm,  which means the allowable limit of Calcium per kg or per 10⁶ mg or 1000000 mg of soil is 540 mg.

ppm is generally used to keep the specification of an impurity in the main Analyte or API. It is expressed in terms of weight by weight (w/w) and volume by volume (v/v).

mcg

It stands for microgram. It is the unit of weight. It is expressed as  weight by volume

mcg or µg= (1/1000)mg or 1mg=1000 mcg or µg

mcg/ml/µg/ml

It stands for microgram out of 1 ml or microgram per ml. mcg/ml or µg/ml is used to specify the concentration in solution and not to specify the impurities limit.

Example:

• 5000mcg/ml or µg/ml of ethanol in water; which means 1ml water contains 5000 microgram of Ethanol
• 890 mcg/ml or µg/ml of toluene in Toluene which means 1ml Ethanol contains 890 micrograms of toluene

Relation between % and ppm

%=(ppm/1000000)×100

Case study: What will be the percentage of 5000 ppm Ethanol?

%=(5000/1000000)×100=0.5%

Relation between ppm, mg and litre (L) and Kg

• 1 ppm = 1 mg/L or
• 1 ppm = 1 mg/Kg

What is the difference between mcg and ppm?

• ppm is used to specify impurity or a substance (at low concentration) in the main substance whereas mcg/ml is used to specify the dilution
• ppm is relative to the main compound whereas mcg/ml is relative to the solvent used for dilution
• ppm is denoted in w/w or v/v whereas mcg is denoted in w/volume

Conclusion

It is a very important topic since it requires all types of analysis such as chemical analysis, high-performance liquid chromatography, gas chromatography-mass spectrophotometry analysis etc. Therefore mastery over this topic is required. This is all related to the post. Now I can assume that this post must have cleared all your doubts related to ppm and mcg.Please write your learning and questions in the comment section. It will motivate me to bring more such skill-based posts to you.

FAQs

What is the full form of ppm?

Parts per million

How do you convert ppm to microgram?

By dividing 1000000.

It means 1 ppm is equal to 1/1000000 mg or 0.000001mg

How do you convert mcg to ppm?

pm and mcg both are same. ppm is used to specify impurity or a substance (at low concentration) in the main substance whereas mcg/ml is used to specify the dilution

What is relationship between ppm and mcg?

ppm and mcg both are same. ppm is used to specify impurity or a substance (at low concentration) in the main substance whereas mcg/ml is used to specify the dilution

What is 1 ppm equal to?

Following is the relationship between % and ppm

%=(ppm/1000000)×100.

Therefore 1 ppm is equal to 0.0001%. It means a drug substance contains 1 ppm of Benzene (as a impurity) and a drug substance contains of Benzene (as a impurity) 0.0001% are same.

What is 100 ppm equal to?

Following is the relationship between % and ppm

%=(ppm/1000000)×100. Therefore 100 ppm is equal to 0.01%.

Is 1 ppm equal to 1 microgram /ml?

Yes

How many ppm in a mg?

1 mg is equal to 1000000 ppm

Can you convert ppm to mg and Kg?

Yes. ppm is a relative value and it is used to specify impurity or a substance (at low concentration) in the main Drug substance/ main Analyte whereas mg and Kg are absolute terms.

1 ppm is equal to 1/1000000 mg or 10^-6 mg or 10^-18 Kg. For example Paracetamol drug substance having toluene as an impurity and its value is 1 ppm. We can say paracetamol have 1 ppm of toluene or 10^-6 mg of toluene or 10^-18 Kg of toluene.

Abbreviations:

• ppm: Parts per million
• mcg or µg: microgram
• mcg/ml or µg/ml: microgram per ml
• w: weight
• v: volume
• mg: milligram
• L: litre
• Kg: kilogram