Quantification of bromide ion in biological samples using headspace gas chromatography-mass spectrometry

OBJECTIVES

In this study, we aimed to establish a method for quantifying bromide ions (Br- ) in blood and urine using gas chromatograph-mass spectrometer (GC-MS) equipped with a headspace sampler, for biological monitoring of workers exposed to methyl bromide.

METHODS

Samples were mixed with dimethyl sulfate, and Br- ions were detected using GC-MS with a headspace sampler. The validity of the proposed method was evaluated based on most of the US FDA guidance. The values obtained were compared with reference values by analysis using SeronormTM Trace Elements Whole Blood L-1 RUO.

RESULTS

The calibration curve showed good linearity in the Br- concentration range of 0.1-20.0 mg/L, and the coefficient of determination R2 value was >.999. Intraday and interday accuracy values were 99.3%-103.1% and 97.4%-101.8%, respectively. The measured and reference values of Seronorm were concordant. Herein, eight urine and serum samples of workers were analyzed; the samples' Br- concentrations were known. The correlation coefficients of urine and serum samples were 0.97 and 0.96, respectively, and results were consistent.

CONCLUSIONS

This study established a simple and rapid method for the determination of Br- concentration in biological samples using GC-MS with a headspace sampler. Moreover, it can be used for biological monitoring of occupational exposure to methyl bromide and for the determination of Br- concentration in a wide range of biological samples.

Exposure Assessment, Biological Monitoring, and Liver Function Tests of Operating Room Personnel Exposed to Halothane in Hamedan Hospitals, West of Iran

BACKGROUND

Occupational exposure to halogenated hydrocarbons has been associated with halothane hepatitis, an increase of liver enzymes, and congenital malformations. The objectives of this study were to investigate whether bromide, a urinary metabolite of halothane, could be used as a biological marker of exposure to this anesthetic gas and assessment of associated exposure to halothane with any significant changes in conventional parameters of liver function (serum aminotransferase activities).

STUDY DESIGN

A cross-sectional study.

METHODS

Seventy-five anesthesiologists, anesthesia nurses, operating room nurses, and surgeons (exposed group) and 75 matched unexposed individuals (reference group) were selected randomly from two public hospitals in Hamadan City, western Iran.  Atmospheric concentrations of halothane in the breathing zone of the exposed subjects and urinary bromide levels were measured by headspace gas chromatography. Similarly, serum activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured by the enzymatic method using an automatic Prestige instrument.

RESULTS

Mean atmospheric concentrations of halothane and urinary bromide levels for exposed subjects were 1.49 ±1.36 ppm and 0.83 ±0.29 mM, respectively. A relatively good correlation was found between exposure to halothane and urinary bromide levels (r=0.38). The chi-squared test results showed that the proportions of the subjects with abnormal ALT and AST among the women exposed were significantly higher than those of reference individuals (P<0.05).

CONCLUSIONS

Urinary bromide can be used as a potential biomarker of exposure to halothane, although additional studies are necessary to further validate these initial findings.

Occupational exposure in methyl bromide manufacturing workers: 17-year follow-up study of urinary bromide ion concentration for biological monitoring

To elucidate the circumstances of their occupational exposure to methyl bromide (MeBr), we conducted a 17-yr study on 124 workers employed by a MeBr manufacturer. Subjects were classified into three groups according to the nature of their work: synthesis group, filling group, and other group. Urinary concentrations of bromide ion (Br(-)) were assessed, and data attained via MeBr-health examinations were analyzed. The highest Br(-) concentrations were seen in the synthesis group, with a median value of 13.0 μg/mg CRE (2.5-51.8), followed by the filling group, with a concentration of 11.9 μg/mg CRE (3.1-34.8). Both values were significantly higher than the levels noted in the other group (p<0.001). Three major opportunities for exposure were identified: during exchange of reaction equipment for maintenance or cleaning, during operations to adjust for weight variations after filling canisters, or when canisters were recycled. Overall, however, the workplace environment concentration remained largely below the administrative control level throughout the study period. Therefore, while this was a relatively well-controlled workplace, exposure opportunities still arose when performing certain tasks, indicating the need for ongoing improvement in workplace procedures and underscoring the importance of biological monitoring.

Urinary Bromide and Breathing Zone Concentrations of 1-Bromopropane from Workers Exposed to Flexible Foam Spray Adhesives

1-Bromopropane (1-BP) has been marketed as an alternative for ozone depleting solvents and suspect carcinogens and is in aerosol products, adhesives and solvents used for metal, precision and electronics cleaning. Toxicity of 1-BP is poorly understood, but it may be a neurologic, reproductive and hematologic toxin. Sparse exposure information prompted this exposure assessment study using air sampling, and measurement of urinary metabolites. Mercapturic acid conjugates are excreted in urine from 1-BP metabolism involving removal of bromide (Br) from the propyl group. One research objective was to evaluate the utility of urinary Br analysis for assessing 1-BP exposure using a relatively inexpensive, commercially available method. Complete 48 h urine specimens were obtained from 30 workers on two consecutive days at two facilities using 1-BP adhesives to construct polyurethane foam seat cushions and from seven unexposed control subjects. All of the workers' urine was collected into composite samples representing three daily time intervals (at work; after work but before bedtime; and upon wake-up) and analyzed for Br ion by inductively coupled plasma-mass spectrometry. Full-shift breathing zone samples were collected for 1-BP on Anasorb carbon molecular sieve sorbent tubes and analyzed by gas chromatography-flame ionization detection via NIOSH method 1025. Geometric mean (GM) breathing zone concentrations of 1-BP were 92 parts per million (p.p.m.) for adhesive sprayers and 11 p.p.m. for other jobs. For sprayers, urinary Br concentrations ranged from 77 to 542 milligrams per gram of creatinine [mg (g-cr)(-1)] at work; from 58 to 308 mg (g-cr)(-1) after work; and from 46 to 672 mg (g-cr)(-1) in wake-up samples. Pre-week urinary Br concentrations for sprayers were substantially higher than for the non-sprayers and controls, with GMs of 102, 31 and 3.8 mg (g-cr)(-1), respectively. An association of 48 h urinary Br concentration with 1-BP exposure was statistically significant (r(2) = 0.89) for all jobs combined. This study demonstrates that urinary elimination is an important excretion pathway for 1-BP metabolism, and Br may be a useful biomarker of exposure.

Determination of bromide in whole blood and urine from humans using gas chromatography-mass spectrometry

We devised a sensitive and simple method for determination of bromide in whole blood and urine from humans using gas chromatography-mass spectrometry. Bromide was alkylated with pentafluorobenzyl p-toluenesulphonate in the mixture of acetone and phosphate buffer (pH 6.8). The derivative obtained was analyzed using gas chromatography-mass spectrometry with the positive-ion EI mode. The lower limit of detection for the compound was 1 mg/l. The calibration curve for bromide was linear over the concentration range from 2 to 100 mg/l. With use of this method, levels of bromide in whole blood and urine were determined in cases of poisoning by inhaled brominated hydrocarbons.

Biological half-life of bromide in the rat depends primarily on the magnitude of sodium intake

The parallel course of the excretion rates of bromide and sodium ions was demonstrated in adult male and female rats administered simultaneously with potassium 82Br-bromide and 24Na-sodium chloride. The animals were exposed to various intakes of sodium ions accompanied with five different anions: Br-, Cl-, HCO3-, ClO4-, and SCN-. Regardless of the anion accompanying the sodium ion, the excretion rates of 82Br- and 24Na+ ions were proportional to the magnitude of sodium intake in the animals. Hence, we have proved our hypothesis that the biological half-life of bromide depends on the magnitude of sodium intake rather than on the intake of chloride.

Biological half-lives of bromide and sodium in the rat are connected and dependent on the physiological state

The parallel course of the excretion rates of sodium and bromide ions was demonstrated in adult male rats administered simultaneously with 24Na-sodium chloride and 82Br-bromide. These excretion rates were inversely proportional to the magnitude of sodium intake in the animals. The biological half-life of bromide, as a substitute for sodium or chloride, was investigated with the aid of the radionuclide 82Br in animals situated in very different physiological states (i.e., in lactating and nonlactating female rats as well as in young rats of varying ages [2, 4, 6, and 10 wk of age]). The 82Br radioactivity retained in mothers and in whole litters was measured in vivo at appropriate time intervals (up to 240 h) after the application of 82Br-bromide to the mothers. The time-course of the changes in the 82Br radioactivity of the young was calculated as the difference between the rate of 82Br intake in the mother's milk and the 82Br excretion through the kidneys into the urine. The rate of 82Br excretion through the kidneys of the dam could be calculated also. Nonweaned young rats (12 d) had the highest half-life (269 h) and lactating dams had the lowest (44 h). The determined values demonstrated that nonweaned young apparently conserve sodium, because of its relatively low concentration in mother's milk, whereas lactating dams, because of their large food intake, waste sodium.

Comparison of urinary bromide levels among people in East Asia, and the effects of dietary intakes of cereals and marine products

Groups of people with no occupational exposure to Br-containing chemicals (29-54 year old, mostly women) in Japan, China and Korea, respectively, offered spot urine samples. Those in China and Korea offered 24 h duplicates of foods of the day. Urine samples were analyzed for Br by ECD-gas chromatography (ECD-GC) after derivatization to methyl bromide, and the Br-U was adjusted for a specific gravity of 1.016. Food intake data were based on national statistics and supplemented by the food duplicate data. Mean Br-U was 5.4 and 6.5 mg/l for Japanese men and women, respectively. Mean levels were in a range of 1.8-2.8 mg/l for four groups of Chinese, and 8-12 mg/l for the four groups of women in Korea. Br-U levels among Korean women were close levels reported for occupational exposure to 1- or 2-bromopropane, or methyl bromide. Regression analyses showed that Br-U levels were influenced by the intake of marine products (such as sea algae, sea fish and shellfish) and fruits, and inversely relate to intakes of cereals and potato.

Urinary bromide levels probably dependent to intake of foods such as sea algae

The purpose of the present study is to examine if the bromide (Br) level in urine (Br-U) varies substantially among adult general populations of either sex or of different dietary habits. For this purpose, morning spot urine samples (about 50 per group) were collected from six groups of people, i.e., one group each of men and women in a city in Japan (thus two groups in Japan) and one group each of women in two urban and two rural areas in central and northeast China (four groups in China). The samples were analyzed for Br by ECD-gas chromatography after derivatization to methyl bromide. Br-U essentially followed a normal distribution. Whereas there was only a marginal difference in Br-U between men (7.7 +/- 2.5 mg/L as an arithmetic mean and arithmetic standard deviation) and women (8.1 +/- 2.9 mg/L) in Japan, and no difference between the urban (2.3 +/- 0.8 mg/L) and rural women (2.6 +/- 1.1 mg/L) in China, the difference between Japanese (8.1 +/- 2.9 mg/L) and Chinese women (2.3 +/- 0.8 mg/L for two cities and 2.6 +/- 1.1 mg/L for two villages) was substantial. A literature survey suggested variation in dietary habits, especially that in sea algae intake, is a possible factor affecting the observed difference in Br-U between the two ethnic groups. Contribution of Br in cereals after fumigation with, e.g., methyl bromide, was also thought to be possible. The implication of difference in background Br-U levels is discussed in relation to biological monitoring of exposure to Br-containing industrial chemicals, such as 1- and 2-bromopropane.

Human halothane metabolism, lipid peroxidation, and cytochromes P(450)2A6 and P(450)3A4

OBJECTIVE

Halothane undergoes both oxidative and reductive metabolism by cytochrome P450 (CYP), respectively causing rare immune-mediated hepatic necrosis and common, mild subclinical hepatic toxicity. Halothane also causes lipid peroxidation in rodents in vitro and in vivo, but in vivo effects in humans are unknown. In vitro investigations have identified a role for human CYPs 2E1 and 2A6 in oxidation and CYPs 2A6 and 3A4 in reduction. The mechanism-based CYP2E1 inhibitor disulfiram diminished human halothane oxidation in vivo. This investigation tested the hypotheses that halothane causes lipid peroxidation in humans in vivo, and that CYP2A6 or CYP3A4 inhibition can diminish halothane metabolism.

METHODS

Patients (n = 9 each group) received single doses of the mechanism-based inhibitors troleandomycin (CYP3A4), methoxsalen (CYP2A6) or nothing (controls) before a standard halothane anaesthetic. Reductive halothane metabolites chlorotrifluoroethane and chlorodifluoroethylene in exhaled breath, fluoride in urine, and oxidative metabolites trifluoroacetic acid and bromide in urine were measured for 48 h postoperatively. Lipid peroxidation was assessed by plasma F2-isoprostane concentrations.

RESULTS

The halothane dose was similar in all groups. Methoxsalen decreased 0- to 8-h trifluoroacetic acid (23 +/- 20 micromol vs 116 +/- 78 micromol) and bromide (17 +/- 11 micromol vs 53 +/- 49 micromol) excretion (P < 0.05), but not thereafter. Plasma F2-isoprostanes in controls were increased from 8.5 +/- 4.5 pg/ml to 12.5 +/- 5.0 pg/ml postoperatively (P < 0.05). Neither methoxsalen nor troleandomycin diminished reductive halothane metabolite or F2-isoprostane concentrations.

CONCLUSIONS

These results provide the first evidence for halothane-dependent lipid peroxidation in humans. Methoxsalen effects on halothane oxidation confirm in vitro results and suggest limited CYP2A6 participation in vivo. CYP2A6-mediated, like CYP2E1-mediated human halothane oxidation, can be inhibited in vivo by mechanism-based CYP inhibitors. In contrast, clinical halothane reduction and lipid peroxidation were not amenable to suppression by CYP inhibitors.

Determination of the halothane metabolites trifluoroacetic acid and bromide in plasma and urine by ion chromatography

Halothane (CF3CHClBr), a widely used volatile anesthetic, undergoes extensive biotransformation in humans. Oxidative halothane metabolism yields the stable metabolites trifluoroacetic acid and bromide which can be detected in plasma and urine. To date, analytical methodologies have either required extensive sample preparation, or two separate analytical procedures to determine plasma and urine concentrations of these analytes. A rapid and sensitive method utilizing high-performance liquid chromatography-ion chromatography (HPLC-IC) with suppressed conductivity detection was developed for the simultaneous detection of both trifluoroacetic acid and bromide in plasma and urine. Sample preparation required only ultrafiltration. Standard curves were linear (r2> or =0.99) from 10 to 250 microM trifluoroacetic acid and 2 to 5000 microM bromide in plasma and 10 to 250 microM trifluoroacetic acid and 2 to 50 microM bromide in urine. The assay was applied to quantification of trifluoroacetic acid and bromide in plasma and urine of a patient undergoing halothane anesthesia.

Extracellular volume estimation from ratios of bromide to chloride in urine or saliva

Use of either urine or saliva samples to estimate extracellular water volume was investigated in 10 men using nonradioactive bromide (Br) and in seven newborn piglets using radioactive Br (82Br) and chloride (36Cl). The relation to Br to Cl concentrations in urine enabled an estimation of Br dilution volume from human urine (267 +/- 42 ml/kg, mean +/- SD) that was not significantly different (P = 1.0) from the Br dilution volume calculated from plasma Br concentration (268 +/- 20 ml/kg). Although the Br dilution volume estimated from saliva was not different from that of plasma, the error in the estimates of Br dilution volume from saliva was too large (mean difference, -36 +/- 64 ml/kg) to make its use practical. The data from piglets showed good agreement between 82Br and 36Cl dilution volumes calculated from 4-hr plasma samples (356 +/- 14 ml/kg and 347 +2- 12 ml/kg; P greater than 0.1) and between 82Br dilution volumes calculated from urine 82Br:36Cl and plasma 82Br (360 +/- 31 ml/kg and 356 +/- 14 ml/kg; P greater than 0.1). Extracellular water volume can be estimated in both adult and young animals using the Br dilution volume calculated from urine samples. It requires (i) two urine collections: one before and one 4 to 8 hr after administration of Br; (ii) a measurement or estimate of plasma Cl concentration; and (iii) a correction factor that describes the relationship of the ratio of Br to Cl in urine to that ratio in plasma.

Dietary fluoride, unlike bromide or iodide, counteracts phosphorus-induced nephrocalcinosis in female rats

Supplemental dietary F has been shown to counteract P-induced nephrocalcinosis in female rats. In order to obtain information as to the specificity of this F effect, the effect of other halogens, namely Br and I, on P-induced nephrocalcinosis was studied in weanling female rats. Supplemental dietary Br (5.24 mmol/kg of diet) and I (1.43 mmol/kg of diet) did not influence P-induced nephrocalcinosis, whereas F at equimolar dietary concentrations had marked antinephrocalcinogenic activity. The halogens were added to the diets in the form of KBr, KI, and NaF; the diets were balanced for the kations with Cl salts. The addition of KI to the diet to a concentration of 5.24 mmol/kg caused pronounced growth retardation, decreased feed intake, hepatomegaly, and signs of lethargy. It is concluded that the protective effect of dietary F against P-induced nephrocalcinosis does not extend to other halogens.

[Determination of bromide ion concentration in urine using a head-space gas chromatography and an ion chromatography--biological monitoring for methyl bromide exposure]

A head-space gas chromatography (GC) and an ion chromatography coupled with a conductive detector (IC) were used to evaluate levels of bromide ion in urine. The GC method followed by methylation with dimethyl sulfate, showed higher accuracy (2.7% of relative standard deviation) and lower minimum detection limit (0.4 mg/l) compared to the IC procedure of those values which were 8.7% and 1.0 mg/l. The correlation coefficient between the analytical results of 15 urinary samples by the two methods was 0.793. The bromide ion concentrations detected in 36 urine samples of workers exposed to methyl bromide were averaged at 13.3 +/- 7.7 mg/l. The average bromide ion of the non-exposed group was 7.1 +/- 2.1 mg/l (n = 6). Exposed methyl bromide concentrations of workers were monitored with passive samplers during their work shifts (8 hr). No significant correlation between exposed methyl bromide and bromide ion concentrations in urine was observed.

Evaluation of methyl bromide exposure on the plant quarantine fumigators by environmental and biological monitoring

The study was undertaken to assess the potential risk of exposure to methyl bromide (MB) gas of plant quarantine fumigators who wore full facepiece gas masks with respirator canisters. The mean ambient concentrations of MB determined by a personal sampling device exceeded the TLV-ACGIH level of 5 ppm in the degassing processes at three fumigation sites except at the silos. The mean urinary bromine concentration of 379 non-MB workers was 6.3 +/- 2.5 mg/l with 95% confidence limits of 10 mg/l. There were 44.6% of 251 MB workers whose urinary bromine levels exceeded the 10 mg/l. There was a significantly positive correlation between the urinary bromine concentrations of the MB workers and the ambient MB concentrations in the degassing process. The MB levels in the workers' exhalation were positive in the degassing process, while those were below the detection limit in the dispersion process. Three possible routes through which the workers are exposed to MB gas are considered to exist: leakage through the interstice between the facepiece of a gas mask and the wearer's face, breakthrough of MB gas in the respirator canister, and percutaneous absorption of MB gas. Biological monitoring of urinary bromine and exhalatory MB as well as environmental monitoring of the ambient MB provided useful information for evaluating exposure of workers to MB.

Halothane metabolism in children

Halothane (1% v/v inspired) was administered for 60 min to six children of mean age 74 months (range 14-119 months). Uptake of halothane was measured from the difference in the concentration in inspired and expired gas and varied from 176 to 310 mg kg-1, depending on minute ventilation. After administration of halothane ceased, its elimination in expired gas was measured in four patients until the conclusion of anaesthesia; 32-37% of the absorbed halothane was expired 90 min after halothane administration ceased. Urinary excretion of trifluoroacetic acid, fluoride and bromide was measured for up to 1 week. Of the absorbed halothane, 11.4% (range 6.3-18.2%) was excreted in urine as trifluoroacetic acid and 0.37% (range 0.10-0.64%) as inorganic fluoride. The urinary half-life of trifluoracetic acid was 41.8 h (range 10.4-59.1 h). The quantitative and qualitative metabolism of halothane via the reductive and oxidative pathways in children are comparable to values found in adults. No differences in the metabolism of halothane by children were found which would explain the different incidence of halothane-associated hepatitis compared with adults.

Determination of nitrite, sulphate, bromide and nitrate in human serum by ion chromatography

An ion chromatographic method has been developed for the determination of trace amounts of nitrite, sulphate, bromide and nitrate in human serum, using an ODS column dynamically coated with cetylpyridinium chloride. The anions studied were eluted with 1 mM citrate - 2.5% methanol (pH 6.5) as the mobile phase and detected by an ultraviolet detector. The interfering proteins in human serum were removed by an initial filtration through an ultrafilter-paper. The many inorganic and organic anions commonly found in serum had little effect on the determination of the four anions. Recoveries of nitrite, sulphate, bromide and nitrate in serum were 107-110, 94-106, 106-110 and 92-100%, respectively. The proposed method was also applied to human saliva and urine.

Determination of iodide and bromide by ion chromatography with post-column reaction detection

During an investigation into the mechanism of the biosynthesis of thyroid hormones, it became necessary to determine traces of iodide and bromide in biological matrices as well as in food. A vydac 302-IC anion-exchange column with methanesulphonic acid as the mobile phase was used for the ion chromatographic separation of iodide and bromide. A post-column reaction detector was developed based on the reaction between iodide or bromide, chloramine-T and 4,4'-bis(dimethylamino)diphenylmethane. Methods with minimal sample preparation are described for determination of iodide or bromide in serum, milk, salt and water. The detection limit is ca. 20 pg iodide and 15 ng bromide injected.

Asymptomatic hyperbromidaemia detected as pseudohyperchloridaemia measured with an ion selective electrode meter

Six patients were found to have increased serum chloride concentrations when these concentrations were determined with an ion-selective electrode, but not when determined by continuous flow mercuric thiocyanate colorimetry or amperometric-coulometric titration. Their serum bromide levels of 1.8-8.0 mmol/l were much higher than those of 0.07-0.13 mmol/l in normal controls. The urinary bromide excretion, measured in two of these patients, was higher than that in normal subjects. No common symptoms or abnormalities in laboratory findings except hyperbromidaemia were found in these patients, who claimed not to have taken any drugs containing bromide. For determination of the incidence of subclinical hyperbromidaemia, the serum bromide concentrations were measured in sera of 1,323 outpatients sent to Tokushima University Hospital for routine measurements of blood chemistry over a one-month period. Five samples showed abnormally high bromide levels. It is concluded that subclinical hyperbromidaemia is not as rare as generally thought, though the aetiology of this state is unknown. Chloride determination with an ion-selective electrode can be used to screen for hyperbromidaemia, since increased levels of bromide ion result in apparently high chloride values.

Comparison of oral and intravenous administration of sodium bromide for extracellular water measurements

Extracellular water (ECW) is a component of body composition and an indicator of nutritional status. Although bromide has been used to measure ECW, no data regarding serial measurements are available. We attempted to validate giving bromide orally and to determine whether serial measurements of ECW are possible. Seven healthy adult volunteers were studied. Each received 1 cc 3% NaBr solution per kg body weight once intravenously and 3 times orally over 6 wk. Bromide concentrations were determined by neutron activation. ECW did not differ significantly at 2, 3, or 4 h after drug administration although there was a small but significant difference between modes of administration (p = less than 0.05). With repeated oral doses the estimate of ECW was unchanged; thus, oral bromide can be used for serial determination of ECW.

Determination of bromide ion concentration in greyhound urine by ion chromatography

An ion chromatographic method was used to determine Br ion in the urine of Greyhounds. Phenol was added to the urine, before filtration through a 30,000-molecular weight cutoff filter and to the eluant (pH 11, NaOH-Na2CO3), as a preservative. Urine from 103 racing Greyhounds resulted in a mean +/- SD of 3.60 +/- 2.72 mg of Br/L of urine. Urine samples obtained from a Greyhound, to which 2 g of KBr was administered, yielded a diurnal elimination pattern with a half-life of 7.6 days.

The metabolism of 1,3-dibromopropane by the rat

1. The metabolism of 1,3-dibromopropane had been investigated in the rat. Two conjugated metabolites have been isolated from the urine and identified as S-(3-hydroxypropyl)cysteine and N-acetyl-S-(3-hydroxypropyl)cysteine. 2. An oxidation product, identified as beta-bromolactic acid, has been isolated as a urinary metabolite. 3. 1,3-dibromopropane is not excreted unchanged in expired air or in the urine. Approx. 15% of the dose (100 mg/kg) is excreted as metabolic products over 50 h and 3.5% as CO2 within 6 h, indicating that oxidation is the main route of detoxication.

Halothane biotransformation in anesthetists

Serum bromide levels were measured in 115 anesthetists by use of x-ray fluorescence spectrometry. Bromide levels peaked at 184 +/- 21 micron in anesthetists regularly exposed to halothane (n = 20), at 58 +/- 4 micron in anesthetists sporadically exposed to halothane (n = 71), and at 46 +/- 3 micron in nonexposed anesthetists (n = 24). Kinetic studies were carried out in five other anesthetists after ten days of exposure to halothane. Average daily halothane concentration was 19.2 +/- 3.2 ppm; duration of exposure was 3.8 +/- 0.2 hours/day. Mean serum bromide level increased from 40 +/- 4 micron before exposure to 220 +/- 36 micron on the last day of exposure. Serum bromide half-life was 14 +/- 1.7 days. The study demonstrates that anesthetists debrominate halothane in a dose-related fashion. Serum bromide levels achieved, however, were far below those reported to result in clinical bromism.

[A method for the determination of bromide in urine with an ion-sensitive electrode (author's transl)]

A potentiometric method for determining the concentration of bromide in human urine is described. On account of its specificity and precision, this method is especially suited for the determination of slightly elevated bromide concentrations due to occupational exposure to alkyl bromides. The rate of recovery is 102.5 to 112.5%, and the variability coefficients lie between 5.8 and 8.6%. The detection limit is about 0.013 mmol/l. The concentrations of bromide in the urine of a group of normal persons lie between 0.059 and 0.162 mmol/l.