The amino-groups of the proteins of human serum. Action of formaldehyde and ninhydrin

Specific Group Reagents for Proteins.

“…Since ninhydrin has been used in the determination of amino groups, it appeared likely that it might be a specific reagent for these groups (83,84,92).…”

Gravimetric Estimation of Proteins Precipitated by Trichloroacetic Acid

“…to chloroform and carbon dioxide (10,13,21). It has been reported (8,9) that precipitated serum proteins in the moist state retain 0.550 mg. of trichloroacetic acid per gram of protein; a great part of this retained trichloroacetic acid was eliminated by drying of the precipitates at 105°C. for 24 hours, but the weights of these precipitates were found to represent 108% of the weights of serum proteins precipitated by acetone or alcohol and similarly dried.…”

Flame Photometric Determination of Calcium, Strontium, and Barium in Mixture

“…By subtracting a linear correction from the emission intensity readings, it is possible to obtain accurate results, rapidly and simply, without separation. THE use of flame photometric procedures has received wide attention in recent years for the determination of sodium, potassium, magnesium, and calcium in plant tissues (2, 8). Studies in this laboratory concerned with the absorption and utilization of the alkaline earths by plants has necessitated a rapid and accurate estimation of small quantities of calcium, strontium, and barium individually and in mixtures.…”