soda-lime and ethyl-violet

Ethyl violet is added to carbon dioxide absorbents and normally serves as an indicator of absorbent exhaustion. During the course of several prior studies of anesthetic breakdown, we noted (but did not publish) that barium hydroxide lime (BL), but not soda lime, turns yellow upon desiccation. We hypothesize that ethyl violet undergoes chemical reaction to produce a yellow colorant in desiccated BL. We qualitatively studied the time course of yellow color development during desiccation of these absorbents with dry oxygen. The yellow colorant was extracted from desiccated absorbent with diethyl ether, separated with chromatography, and analyzed with proton nuclear magnetic resonance and combined gas chromatography and mass spectrometry. The yellow color develops after BL has reached nearly complete desiccation. We successfully identified that ethyl violet decomposes into the yellow colorant 4,4'-bis(diethylamino)benzophenone upon desiccation of BL. The color is not intense, is not useful for identifying low levels of absorbent desiccation, and may be difficult to see through tinted canisters. It may be possible for BL to be sufficiently desiccated to allow chemical breakdown of anesthetics, but not yet show yellow coloration. However, if yellow coloration exists, one should assume that it has become desiccated.

Topics: Anesthesiology; Barium Compounds; Calcium Compounds; Chromatography, Thin Layer; Color; Coloring Agents; Desiccation; Oxides; Rosaniline Dyes; Sodium Hydroxide

Contamination was suspected of U.S. Navy Fleet soda lime (High Performance Sodasorb) when an ammonia-like odor was reported during its use in August 1992. This material contained indicator dye and was used for carbon dioxide absorption during diving. This incident had a major impact on the U.S Navy diving program when the Navy temporarily banned use of Sodasorb and authorized Sofnolime as an interim replacement. The Naval Medical Research Institute was assigned to investigate. Testing involved sampling from the headspace (gas space) inside closed buckets and from an apparatus simulating conditions during operational diving. Volatile organic compounds were analyzed by gas chromatography and mass spectrometry; ammonia and amines were measured by infrared spectroscopy. Significant amounts of ammonia (up to 30 ppm), ethyl and diethyl amines (up to several ppm), and various aliphatic hydrocarbons (up to 60 ppm) were detected during testing of both Sodasorb and Sofnolime. Contaminants were slowly removed by gas flow and did not return. The source(s) of the ammonia and amines are unknown, although they may result from the breakdown of the indicator dye. Hydrocarbon contamination seems to result from the materials of which the bucket is constructed. Unfortunately, evaluation of potential hazards associated with this contamination is difficult, due in part to the large number of variables of operational use and the absence of appropriate exposure limits. Based on these findings, the U.S. Navy has begun to phase in, for all diving, non-indicating soda lime that will be required to meet defined contaminant limits.

Topics: Amines; Ammonia; Calcium Compounds; Chromatography, Gas; Consumer Product Safety; Diethylamines; Diving; Drug Contamination; Drug Packaging; Hydrocarbons; Oxides; Rosaniline Dyes; Sodium Hydroxide; United States

Topics: Anesthesia, Closed-Circuit; Calcium Compounds; Carbon Dioxide; Color; Equipment Safety; Indicators and Reagents; Oxides; Rosaniline Dyes; Sodium Hydroxide

Topics: Adult; Anesthesia, Closed-Circuit; Calcium Compounds; Color; Equipment Safety; Female; Humans; Indicators and Reagents; Oxides; Rosaniline Dyes; Sodium Hydroxide

The choice of ethyl violet as a pH indicator in soda lime is not the best. Color change happens too late because pH alteration of the surface of soda lime is slower than in the core of the canister. Clinical and comparative measurement of wall temperature of two in series canisters is a good precaution. If the down stream canister is warmer than the upstream one, you must change the latter.

Topics: Anesthesia, Closed-Circuit; Calcium Compounds; Humans; Hydrogen-Ion Concentration; Oxides; Rosaniline Dyes; Sodium Hydroxide