Separation of iodide, bromide, and chloride from one another and their subsequent determination

Abstract

A m ethod is described fo r ~e]Jarat in g iod id e, b romid e, a nd chl o ride from one a not he r . First. th e iodid e ion is ox idi zed to eleme n tary iod ine b y h yd roge n p er oxide ill weak lv acid so lutio n a nd t he iodin e re mo ved b.v d istillat io n. Kext, bron Jide is oxidi zed to bro mine \~itho u t a fl.'c ct in g t he c hlorid e ion by use of a co nt roll ed con cen t rat ion of ni t ric a cid as ox id iz in g a ge n t . Af to r re mo va l o f bro llllll e b .v dlst dl a tlon , c hl o l'ld e re ma In s II1 t he reS Idu a l so lu t ion .D ete rmin a ti o n of th e indi v! du a l ha lid es depe nds on th e qu a n t ity of eac h. If in t race am oll n ts, a t lll'b id im et ri c m et hod is used; iF in larger a mo un ts, p otent io met l'l c t itr ation \\' ith s il ve r nit rat e is Ii sed.A d escript io n o f t he apparat us IIsed is a lso give n .

A simple distillation method to extract bromine from natural water and salt samples for isotope analysis by multi‐collector inductively coupled plasma mass spectrometry

“…As it has long been known that a dilute HNO 3 solution will oxidise Br − , but not Cl − , Murphy et al developed a method to quantitatively separate Br from Cl. During the oxidation of Br − , Br 2 is formed and in alkaline solutions the Br 2 is disproportionated into Br − and BrO − , the latter of which subsequently disproportionates to Br − and BrO 3 − as follows: …”

“…The method that we developed for the analysis of Br isotopes follows this procedure with several modifications: At IPGP, Br isotopes are routinely measured in a 0.2 M NH 4 NO 3 solution, which results from ion exchange chromatography for Br extraction as described by Louvat et al We found it appropriate to keep this medium (0.2 M NH 4 NO 3 ) for the new method as it has proven to produce reproducible measurements of Br isotope ratios and fast washouts. The use of the same medium for both analytical procedures (distillation and ion exchange) also allows for immediate comparison between the two methods when they are used to extract Br from geological samples.…”

“…The use of the same medium for both analytical procedures (distillation and ion exchange) also allows for immediate comparison between the two methods when they are used to extract Br from geological samples. For that reason the distilled Br 2 was trapped in an ammonia solution. While Murphy et al used a 300 mL distillation flask, as the size of our samples is mostly between 1 and 25 mL, such a large flask would be very inconvenient, especially because the volume of the distilled solution should be as small as possible (roughly about 2 mL) to obtain a good signal level during analyses. The main objective of this new method is the analysis of natural water and salt samples. In order to facilitate this and to ensure that results are comparable with those obtained by the methodology developed by Louvat et al, a series of tests was conducted in order to optimise the distillation time, ammonia concentration and final pH.…”

Absolute isotopic abundance ratio and the atomic weight of bromine

“…Dilute nitric acid (1: 5) has been shown to oxidize bromide to bromine quantits.tively [8] without oxidizing chloride to chlorine. Chloride analyses .l8] of the distillands after removal of the bromme sh owed that the chloride concentration was less than 0.001 percent in terms of the NaBr present.…”

“…Each separated isotope sample (abou~ 5 g) .was divided in half and treated as follows: 'Ihe sodmm bromide (about 2.5 g) was dissolved in a small amoU?t of water and transferred to a 300 ml three-neck dIStilling apparatus like that described b:y Murphy, Clabaugh, and Gilchrist [8]. The solutIOn ,:"ol~me was increased to 100 ml and 0.2 ml of redIstIlled nitric acid was added.…”