An automatic titrator for student use

The conversion of undissolved acidic functional groups into dissolved carboxylate anions has been monitored during potentiometric titration of a Typic Mesisol Peat at 25 °C. The analytical chemical calculations of total acid functional groups and of H+ dissociation equilibrium functions take the dissolution process into account. With 0.05 g of sample suspended in 20 mL of 0.1 N NaCl, the molarity of carboxylate anions in the external solution ranged from 4.3 × 10−4 M at 1 mL g−1 0.1 N NaOH, to 1.5 × 10−3 M at 6 mL g−1 0.1 N NaOH. The corresponding amounts of undissolved carboxyl groups were 5.2 × 10−4 and 1.0 × 10−4 mol g−1. Differential acid constants (KGA) for the undissolved carboxyls were 7.6 × 10−4 (σ 1.4 × 10−4) for αG < 0.02 (0.016 – 0.02) and 1.4 × 10−5 (σ 0.04 × 10−5) for αG > 0.026 (0.026 – 0.60). A substantial increase in productivity was achieved by means of an automatic titrator and a microcomputer with spreadsheet software. Types of data production and processing that were previously labor intensive have now become much more practical. Key words: Organic soils, organic matter solubility, organic soil carboxyls, organic soil ion exchange, organic soil titration, pH dependent solubility

Download Full-text

Evaluation of contemporary methods for serum CO2.

Clinical Chemistry ◽

10.1093/clinchem/22.3.374 ◽

1976 ◽

Vol 22 (3) ◽

pp. 374-378 ◽

Cited By ~ 11

Author(s):

J A Lustgarten ◽

R J Creno ◽

C G Byrd ◽

R E Wenk

Keyword(s):

Continuous Flow ◽

Normal Ranges ◽

Automatic Titrator ◽

Standard Deviations

Abstract We evaluated and inter-compared several newer methods for CO2 analysis--titrimetric (Van Slyke), automatic titrator, continuous-flow/indicator, and coupled-enzyme procedures--with respect to accuracy, precision, specificity interferences, and management criteria. All methods studied appeared to be clinically acceptable; but precision decreased (standard deviations increased) for the last two methods in above-normal ranges.

Download Full-text

Evaluation of Procedures for Urinary Calcium

Clinical Chemistry ◽

10.1093/clinchem/10.6.549 ◽

1964 ◽

Vol 10 (6) ◽

pp. 549-558 ◽

Cited By ~ 1

Author(s):

Frank W Fales

Keyword(s):

Direct Analysis ◽

Urinary Calcium ◽

Flame Photometry ◽

Acid Oxidation ◽

Urine Specimen ◽

Colorimetric Analysis ◽

Automatic Titrator ◽

Precision And Accuracy ◽

Emission Flame ◽

True Measure

Abstract In a comparative study of urinary calcium methods, many of the recently proposed procedures proved either impractical or invalid in our hands. A preliminary isolation of the calcium as the oxalate, followed by perchloric acid oxidation of the oxalate seemed to be the simplest procedure whereby urinary calcium could be put in a state suitable for chelometric titration. The isolated calcium could also be titrated with considerable precision and accuracy by a modified procedure with a derivative automatic titrator which is available commercially. It was suggested from our observations that too little attention has been directed towards the problems imposed by the occurrence of calcium precipitates in urine. An untreated 24-hr. urine specimen is not suitable for direct analysis of calcium by chelometric titration, by colorimetric analysis, by emission flame photometry, or by atomic absorption flame photometry because these methods do not give a true measure of the calcium in the precipitate. Boiling for 5 min. with 1 part concentrated nitric acid to 25 parts urine proved a suitable means for completely dissolving the calcium precipitate.

Download Full-text