A filter method for the active and passive monitoring of sulfur dioxide in workplace air.

A method where sulfur dioxide is collected on impregnated filters (glycerol/potassium hydroxide solution) is described. Sampling can be done either with a pump or by the use of two different passive monitors available on the market. Analysis is made by ion chromatography. The methods have been evaluated and compared with a colorimetric air monitoring badge system (ProTek). Laboratory tests show that the accuracy of the filter methods is acceptable and that samples can be stored. Water vapor does not interfere, but hydrogen sulfide causes a minor decrease in recovery. ProTek has high accuracy but storage tends to decrease the recovery. Field tests in a steel rolling mill and a sulfate pulp mill showed a fairly good correspondence between the methods.

Development and evaluation of field methods for ammonia in air.

Three methods for measuring ammonia in air have been evaluated. Filters impregnated with 10% (volume/volume) phosphoric acid in methanol were used for two methods. Sampling was done either with a filter cassette connected to a pump or with the filters placed in a passive monitor (Gasbadge). The filters were leached with distilled water after the sampling and analyzed with ion chromatography or colorimetry (Nessler). The third method tested was a colorimetric air-monitoring badge system (ProTek). The tests showed that the accuracy of the filter methods is good and that the results are not affected by humidity. If ion chromatography is used for the analysis, amines do not interfere. The Gasbadge monitors increased their uptake when the air velocity over the sampler was raised from 0.2 to 1.0 m/s. The accuracy of the ProTek method was poor, the method was biased, and blank samples showed high values. In field tests carried out in a foundry and at a fertilizer plant, the agreement between the filter methods was good, whereas the results of the ProTek method deviated drastically from those of the other methods.

Effects of hepatectomy, nephrectomy, and nephrectomy/uremia on the metabolism of parathyroid hormone in the rat.

Reports from several laboratories, showing extensive hepatic extraction of circulating parathyroid hormone, led us to examine the effect of near-total hepatectomy on the metabolism of the hormone to circulating fragments, and on its clearance from plasma. The rate of disappearance of (125)I-labeled and unlabeled bovine parathyroid hormone from plasma, and the appearance, disappearance, and chemical and immunochemical characteristics of circulating fragments were examined by gel filtration and either sequence-specific radioimmunoassays or sequence analysis using the Edman reaction. Results from awake rats subjected to near-total hepatectomy were compared with those found in sham-treated, nephrectomized, and short-term uremic rats (studied 2 d after nephrectomy). When compared with the sham-treated group, all other groups clear (125)I-labeled hormone more slowly; after hepatectomy, however, the clearance rate is most strikingly decreased. After injection of intact hormone, the concentration of carboxy-terminal fragments in the circulation of hepatectomized rats is greatly reduced at all time intervals when compared with that in sham-treated rats. Sequence analysis of plasma samples, collected from rats into which (125)I-labeled hormone had been injected, shows that carboxy-terminal fragments having positions 34 and 37 of the intact hormone sequence as their amino-terminal amino acids are abundant in sham-treated, nephrectomized, and nephrectomized/uremic rats, but are undetectable in hepatectomized rats. The data suggest that inasmuch as the liver in vivo generates most of the carboxy-terminal fragments resulting from the metabolism of injected hormone, specific cell types within the liver must be the principal locus of the responsible enzyme(s); thus, studies of the enzymic properties of isolated hepatic cells in vitro most likely will yield information of physiologic relevance to the metabolism of the hormone in the intact animal.