Measuring Chlorate, Bromate and Perchlorate In the Lab

In order to test for perchlorate concentrations samples must first be taken from the source being tested; these may be stored in 40-mL vials, and should be stored in a cool, dark place prior to testing. The perchlorate concentrations are then determined by liquid chromatography/mass spectrometry techniques based upon method 331.0 determined by the EPA (Environmental Protection Agency). This particular method allows for the identification of perchlorate either through the use of tandem pass spectrometry or single ion monitoring using dual ions. The primary method of analyzing both drinking water and other environmental samples in order to detect the presence of perchlorate is ion chromatography given both the low detection limit and the selectivity of the ion. In spite of this, there are other confirmatory techniques that may be used on “refractory samples, instances of unexpected occurrence, or complex matrixes” including complexation electrospray mass spectrometry, high-field asymmetric waveform ion mobility spectrometry, and Raman spectroscopy. Liquid-chromatography-mass spectrometry may also be used in order to detect the presence of perchlorate in drinking water and seawater. .

All mass spectrometers utilize an ion source, an ion detector, and a mass analyzer, though these components will vary based upon the type of mass spectrometer used, the type of data that an individual wishes to determine, and the properties of the sample being used. The presence of these three components may be determined using a variety of samples, including the treated water itself, plant life affected by the treatment of the water, or food and beverage products. The samples may be loaded into the mass spectrometer in either liquid or dried, solid form, after which they are vaporized and then ionized by the ion source. The charge received by the ions allows the mass spectrometer to be able to accelerate the ions through the rest of the device, which is where the ions are analyzed as a result of the mass of the ions and the charge of the ions. Ions that are successfully deflected by the analyzers hit the ion detector, either an electron multiplier or a micro channel plate, either of which is designed to emit a cascade of electrons upon being hit by an ion. The process occurs under an extreme vacuum in order to remove the possibility for contamination of the samples. .

The mass spectrometer is connected to a computer, and it is the computer that works to analyze the detected ions, producing graphs that work to organize the ions by their m/z and abundance, after which they are passed through a database in order to determine the resulting type and amount of ions found. Every sample entered into the mass spectrometer requires some form of preparation, used to reduce sample complexity and remove detergents, and/or tagging specific proteins for identification. Without proper sample preparation the results may come into question, as samples must be of the same quality and all samples must be reproducible. Sample preparation may include lysate preparation, peptide or protein enrichment, sample clean up, or protein digestion. Research was being conducted in 2005 in order to determine if there was a way to distinguish between man-made perchlorate and naturally occurring perchlorate, utilizing isotopic mass ratio differences, and performing these tests within a laboratory setting allowed for determination in certain circumstances, though it was found that if Chilean nitrate was used in the production of man-made perchlorate, laboratory tests were unable to distinguish between the two..

In order to test for bromate, bench scale tests are used in order to measure the rates of bromate formation in a variety of solutions, including raw water direct from the source of the utility or treatment plant and in de-ionized water samples; studies have shown that routine disinfection will keep the levels of bromate under the national standards of 10 ug/l, the maximum amount allowed to be present in order to meet drinking water standards. By working to ensure that disinfection protocols are followed, there should be no issue with excessive amounts of the contaminant bromate being present within the resulting drinking water originating from facilities. Disinfection, and the maintenance of disinfectant protocols works to assist not only in the removal of bromate, but in inactivating microorganisms in the distribution system, providing indicators of distribution system upsets, and working to control the growth of biofilm within the agencies and water treatment plants designed to treat drinking water. There are six different pathways that may be utilized by contaminants in order to reach the distribution system, placing themselves in otherwise treated water. In light of these six different pathways, the utilization of a secondary, backup method for the disinfection of water has been recommended and discussed, but there has been, as of yet, no requirement regarding the use of a secondary disinfectant system in standardized water treatment plants. The Surface Water Treatment Rule requires the maintenance and monitoring of all systems that use surface water to have an amount of disinfectant residue present within the distribution system for this water, and if it is not present in accordance with specified levels, additional steps are required to be taken by that facility in order to ensure that those disinfectant residual levels are replaced and maintained..

The limit of chlorate present within delivered bleach is typically 1500mg/liter, or 1500 ppm (parts per million), the testing for which is done in a laboratory setting. Tests for the presence of chlorate may also be done with mass spectrometry, via titrimetric method, comparison of methods, selection of a quenching agent, and metal ion quantification; ion chromatography coupled with conductivity detection may also be used as a valid means of detection. These tests work to determine the levels of chlorate present within a given solution for the purposes of determining whether or not safe levels of this contaminant are present within a given source of liquid. If safe levels of the contaminant are not met, or if the advised limit for these contaminants is exceeded, the plant itself may need to be reviewed, or additional treatment methods may need to be found in order to work to ensure that no adverse effects result from the presence of the contaminant. Depending upon the facility, the location of the facility, and the group in charge of the facility will depend on the additional steps taken in order to work to correct this particular issue as well as the methods taken in order to do so.

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