Many users are reluctant to use 100% organic on their columns – don’t be, columns love it!ģ. Ramp the gradient up to 100% acetonitrile and hold it there for several hours. 90%) to remove any residual buffers that may precipitate in high organic. Start at a high concentration of water (e.g. This would usually mean switching the column to a water: acetonitrile gradient. Flush the column with a strong organic wash for an extended period. If you’re going to dispose of the column anyway, it’s well worth a try.Ģ. Modern columns are more tolerant to being used in reverse, although there is still a risk that reversing will cause permanent damage. If a column is considered unusable, reversing the column is well worth trying – particularly with columns showing high backpressure. If you have already written the column off, there’s no harm in trying the following desperate measures: If column performance has degenerated to a noticeable level the answer is (almost always) no. It can often occur without a significant increase in backpressure. This type of problem results in a decrease in column performance, usually poor peak shape (tailing, fronting, chairing or splitting), a decrease in resolution and a change in retention time. Indirect damage where contamination becomes strongly/permanently bound to the stationary phase, changing column selectivity.Direct damage, such as removal or permanent chemical modification of the stationary phase ligand.This evaluation excluded about 10% of the data, which were identified as outliers.Īpproved for public release distribution is unlimited.The problem with this request is, can it actually be done? We’ve had a look into this for you.įirst, let’s look at two main types of problems that occur with use:Īlthough this includes voids and fissures, these are rare on modern columns and the most common issue we see is physical blockage at the top of the column, with either the frit or the packing interstitial spaces becoming clogged by particulate contamination. For the four analytes collectively, the analytical accuracy was within 5%, the intralaboratory precision (repeatability) was 5 to 9% based on the average of duplicate injections, and the interlaboratory precision (reproducibility) was 7 to 10%. An interlaboratory test of the method was conducted with nine participating organizations, including laboratories at four Army ammunition plants, the EPA's Environmental Monitoring and Support Laboratory, three Army research organizations and a university. The method was tested with munition wastewater from several Army ammunition plants and found to perform adequately for load and pack wastewaters, wastewater from HMX/RDX manufacture and contaminated groundwater. A ruggedness test involving the major manipulative steps in the procedure indicated that use of glass sampling containers, the portion of filtrate chosen for analysis and a carefully measured sample-to-organic-solvent ratio was necessary to obtain consistent analytical results. Analytical precision was estimated at ± 3.4, 3.3, 4.4 and 4.6 μg/L. Detection limits were conservatively estimated to be 26, 22, 14 and 10 μg/L for HMX, RDX, TNT and 2,4-DNT respectively. The method provided linear calibration curves over a wide range of concentrations. An eluent of 50% water, 38% methanol and 12% acetonitrile successfully separated HMX, RDX and TNT from each other and the potential interferents. Retention times of these four analytes, their degradation products, and impurities expected in wastewater matrices were determined for two eluent compositions. The method involves dilution of an aqueous sample with an equal volume of methanol-acetonitrile solvent mixture, filtration through a 0.4 μm polycarbonate membrane and analysis of a 100-μL sub sample by reverse-phase, high-performance liquid chromatography using an LC-8 column. Reverse Phase High Performance Liquid ChromatographyĬold Regions Research and Engineering Laboratory (U.S.)Įngineer Research and Development Center (U.S.)Ībstract: An analytical method was developed to determine the concentrations of HMX, RDX, TNT and 2,4-DNT in munitions wastewater. Army Toxic and Hazardous Materials Agency. Reverse phase HPLC method for analysis of TNT, RDX, HMX and 2,4-DNT in munitions wastewater Please use this identifier to cite or link to this item:
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