Q1: Kjedahl nitrogen is a mixture of

ANS:D - all the above.

1. Ammonia (NH3): Ammonia is a compound composed of one nitrogen atom and three hydrogen atoms. During the Kjeldahl digestion process, nitrogen-containing compounds in the sample are converted into ammonia through chemical reactions. Ammonia is released as a gas and subsequently captured and measured.
2. Organic Nitrogen: Organic nitrogen refers to nitrogen that is bound within organic compounds, such as proteins, amino acids, urea, and other nitrogen-containing molecules present in organic matter. During the Kjeldahl digestion process, organic nitrogen compounds are decomposed and converted into ammonia. The total amount of nitrogen released from organic compounds is measured as part of the Kjeldahl nitrogen determination.

By measuring both the ammonia and the nitrogen released from organic compounds, Kjeldahl nitrogen analysis provides a comprehensive assessment of the total nitrogen content in a sample. This total nitrogen content is often used in environmental testing, agricultural analysis, food science, and other fields to quantify the nitrogen content present, which is crucial for various applications such as assessing water quality, determining protein content in food and feed, and monitoring nitrogen cycling in ecosystems. Therefore, Kjeldahl nitrogen is indeed a mixture of ammonia and organic nitrogen.