Seishi Takagi

Studies on the Digital Measuring Instrument and its Application

Recent measuring techniques are directed toward the using of digital measuring instrument. This instrument shows little or no error in reading as its numerical readings are made automatically. It is desirable to have this digital system of measuring instrument for various appliances to be used for electrochemists. Some digital instruments are on the market in the other countries but no such product is found in here. Attempts have been made by the authors for construction of a measuring instruments of milli-voltmeter type to read in the ranges of 01500 mV with 10 times more accurate than the measuring instruments with usual precision (±0.5%) as ±0.5% accurate for electrochemical estimation is insufficient. However, the accuracy (±0.01%) required for potentiometric type estimation is very seldom, and the construction of a digital measuring instrument with an intermediate accuracy (±0.050.1%) would eliminate the use of the potentiometer.

The Change of Glucose Injection by Sterilization with Heating

Estimation of pH of commercial glucose injections by use of glass electrode showed to be pH 3.54.3. These lower pH values are attributed to the decomposition of glucose by heating to 5-(hydroxymethyl)-2-furaldehyde, its further decomposition gives an equimolar mixture of formic acid and levulinic acid and glucose injections buffer action are very slight and cause much error when estimated by pH indicating papers. The concentration of formic acid and levulinic acid, respectively, is 5 × 10-5 to 5 × 10-4 N. The acidiy can be estimated by high frequency titration or it can be estimated by making a graph from relations of concentration of acid and pH values. Although these lower pH values are considered to be harmless for injection due to its weak buffer action, it is rather striking to note such lower pH values and a sugestion for revision of Pharmacopoeia Japonica VI is made, since it specifies to be pH 5. 07. 0