Eluents perchlorate

Magnesium, calcium, barium, and strontium can also be deterrnined by ion chromatography with y -phenylenediamine in perchloric acid as the eluent. Ion chromatography by conductimetric detection has been described, and appHcations to environmental waters have been discussed (1,22—23). 

Finally, the data in Table 8-6 show the elution of the lead column. The eluent is H,0. The driving force for the elution in this case is the lack of C10 present to act as an anion in the binding of the ammonium perchlorate salt pair. The D-enantiomer versus L-enantiomer ratio in the elution is slightly greater than 6 1, as expected by the inherent selectivity of the ligand. For this separation system, LiClO is then added back to the eluent and the eluent is sent on as load to the next purification stage. 

This problem was resolved by Nakae et al. [7] using non-polar octadecylsilica as the stationary phase and a solution of 0.1 M of sodium perchlorate in methanol/water (80 20) as the mobile phase. The ternary system (water-alcohol-salt), previously used by Fudano and Konishi [8] as an eluent for the separation of ionic surfactants at higher concentrations, induced the so-called salting out effect . The addition of the organic solvent to the water modified the polarity of the eluent and produced a good separation within a short period of time [9]. It also has the function of dissociating the surfactant micelles in individual molecules that are dissolved in the eluent [8], The presence of the salt (NaC104) in the mobile phase has a considerable influence on... 

HPLC on a Cosmosil 5 Cis column, using a perchloric acid-acetonitrile eluent (pH 7.6), followed by CLD in the presence of hydrogen peroxide and bis(2,4,6-trichlorophenyl) oxalate (42), was applied to the determination of 1-aminopyrene (43a) and various diaminopyrenes (43b-d). Ascorbic acid was added to avoid oxidative degradation of the aminopyrenes in the presence of metals LOD in the sub-fmol range (SNR 3)147. A fast (less than 10 min) HPLC-ELCD method was proposed for determination of dopamine (19b) and its metabolites in microdialysates, using packed fused silica capillary columns LOD 0.05 Xg/L of dopamine in a 2 XL sample, RSD 3% (n = 10)148. 

Figure 4.7 Anion exchange separation of carboxylic acids in red wine. Column, Shodex C811, 100 cm x 7.6 mm i.d. eluent, 3 mM perchloric acid flow rate, 0.9 ml min-1 temperature, 60 °C detection, reaction detection using chloro-phenol red at 430 nm. Peaks 1, citric acid 2, tartaric acid 3, malic acid 4, succinic acid 5, lactic acid 6, formic acid and 1, acetic acid.

FIGURE 6 Effect of p-cyanophenol on the separation of perchlorate. Column 4x250mm lonPac ASII. Flow rate I.OmLmin. Injection volume 25pL. Detection suppressed conductivity utilizing the Anion Self Regenerating Suppressor (4mm), recycle mode. Ion I—perchlorate (20mgL" ). (a) Eluent lOOmM NaOH. (b) Eluent 50 mM NaOH and 5mM p-cyanophenol. 

Atteberry and Boyd have separated TcO and ReO on Dowex-2 resin using a mixture of 0.1 M (NH j SO and 0.1 M (NH j SCN as eluent. The two elution peaks are partially resolved, but the cross contamination is rather high. Much better results are obtained if perchlorate is used as the elutriant . Because of some peculiarities of commercial resins, the highest practically attainable separation factors of TcO and ReO are l(f -10 It has been found that the volumes of the eluents consumed in the elution of pertechnetate and perrhenate are inversely proportional to the perchlorate concentration. The separation on Dowex 1-X4 is described in Fig. 6. Partial reduction of TcO or ReO reduces the efficiency of the chromatographic separation since the elution peaks frequently become blurred . 

Non-volatile buffers such as phosphates, borates, perchlorates and phosphoric acid should be avoided at all costs because of high background ion current, source contamination and blockages, and in the case of perchlorates, explosions. Figure 6.4 shows the mass spectrum of typical background when using phosphoric acid in the eluent. If the solvent system for a particular analysis does not assist the electrospray process, it is possible to enhance ionisation by postcolumn addition of a suitable volatile buffer. 

When sample components having ionizable groups are chromatographed the use of a background electrolyte and control of the eluent pH with an m>propridte buffer are mandatory. It is advisable to maintain a fairly high concentration of buffer in the medium in order to rapidly reestablish protonic equilibria and to thereby avoid peak sjditting or asymmetrical peaks due to slow kinetic processes. Acetic acid, phosphoric acid, and perchloric acid and their salts have been used for the control of pH. 

Figure 7. Optimal system configuration using AG4 guard column as the concentrator column. Five milliliters of Milli-Q water spiked with CI04" was loaded onto the concentrator column at varying concentrations of perchlorate. Eluent 0.5M 18-crown-6 and 5mM KOFI. Injection 5mL loaded onto concentrator column, flow rate 1.0 mL/min, temperature 20 °C [17].

A qualitative and quantitative HPLC method for analysis of mixtures of 12 antioxidants was described Grosset et al. (121). For the identification of the components present, gradient elution with a convex profile from 35 65 water-methanol to pure methanol is used, on a Waters 5-/xm C18 column, with UV detector. Propyl gallate was not separated by this system. For quantitative analysis, with UV and electrochemical detectors in series, the water-methanol mixture or pure methanol was used as the eluent, under isocratic conditions, with lithium perchlorate as supporting electrolyte. An applied potential ranging from +0.8 to +1.7 V allows detection of all the antioxidants tested. Both modes of detection were very sensitive, with limits of detection as low as 61 pg. 

Lamb, J. D., Simpson, D., Jensen, B., and Peterson, Q. (2004), 18-crown-6 as an Eluent Additive for the Ion Chromatographic Determination of Perchlorate in Drinking Water, in preparation. 

J. H. Kennedy and B. A. Olsen, Investigation of perchlorate, phosphate and ion-pairing eluent modifiers for the separation of cephalosporin epimers, J. Chromatogr., 389 369 (1987). 

Iodide in vitamin tablets can be found by amperometric detection [88]. Nonaqueous eluents of methanol-containing ammonium perchlorate, which are relatively oxidant resistant, have been used in conjunction with a silica column to detect a wide range of drugs [89]. The use of higher potentials not possible in totally aqueous mobile phases allows for the detection of secondary and tertiary aliphatic amines 462 drugs have been detected in this manner. For compounds that are not electroactive, a procedure using a postcolumn photolysis can generate electroactive species [90] for penicillins [91], proteins [92], and barbiturates [93]. 

Davenport and Johnson [30] used ion exchange chromatography on Amberlite IRA-900 strongly basic resin to determine nitrate and nitrite in water. 0.10M perchloric acid was used as eluent and an electrochemical cadmium electrode detector was used. 

To select another eluent to replace perchlorate solution for the displacement of radio-iodine sorbed from milk on an anion exchange resin column in a method that is described in a published article. 

Special attention should be given to the toxicity and safety of any eluent that can replace perchlorate. 

The cell free samples were mixed with perchloric acid/perchlorate and stored at low temperature for 48 h, at 6000 rpm centrifuged, decanted, stored at -22°C for a week and centrifuged again for deproteination. The separation was performed on an ion exclusion polystyrene/divinylbenzene column at 40 °C with 15 mM sulfuric acid as eluent and detection at 205 nm. For the quantification a standard was applied. A typical chromatogram is shown in Figure 6. Pyruvate, succinate, lactate, formate and acetate were detected in the cultivation medium. 

Acid eluents serve a dual function. First, the acid will protonate the amine so that the amine will interact with the resin and the hydrogen ion will serve as the exchange ion in the chromatographic process. The eluent suitable for the separation of aromatic amines is an aqueous perchloric acid solution. Other mineral acids can also be used but may form complexes with metals in the sample or the chromatograph or oxidize components of the sample., ... 

A series of perchloric acid solutions were prepared as the eluent. Each eluent was flushed through the chromatograph until a stable baseline was obtained. Each individual amine was injected onto the column using the 0.5 ml sample loop. The amine was allowed to elute if possible. If after sixty minutes the amine had not eluted, the system was flushed with 1 M HCIO4 to remove the compound. The order of elution of the amine and the effect of eluent concentration on the retention time were determined. 

Because of the cobalt(II) contamination, the perchlorate salt is synthesized and then converted to other salts. Cobalt(II) chloride 6-hydrate (1.0 g, 4 mmole) and free [15]aneN4 (05 g, 4.2 mmole) are warmed in 100 mL of methanol for 15 minutes. Concentrated hydrochloric add is added dropwise (1 mL) and air is bubbled through the solution for at least 2 hours. Several drops of perchloric acid are added to precipitate the products as the perchlorates. The yield is 72%. The product is brown and is about 90% pure isomer I. The brown perchlorate salt is dissolved in acetonitrile and passed through a Dowex 1X8,200-400 mesh anion exchange column (Cl form) at a rate of 10 sec/drop. The eluent is concentrated by rotary evaporation. Some green solid (isomer II) precipitates. This is filtered and the volume of the filtrate is further reduced to precipitate the tan isomer (I) as the chloride salt. Yield 60% Anal. Calcd. for CoC2r H26N4a3 C, 34.80 H, 650 N, 14.76. Found C, 34.35 H, 7.09 N, 14.50. 

Benzodiazepines can be chromatographed with methanolic eluents containing perchloric acid (typically 0.001 M). Retention can be modified by the addition of other organic solvents (e.g. ether) or by changes to the acid concentration. 

Eluent. A solution containing 1.175 g (0.01 M) of ammonium perchlorate in 1000ml of methanol adjust to pH 6.7 by the addition of 1 ml of 0.1 M sodium hydroxide in methanol. k Values. Values for drugs in this system will be found in drug monographs and in the indexes to Analytical Data in Part 3 they are also included in the systems for specific groups of drugs which follow. 

Eluent. Methanol to which has been added 100 pi of perchloric acid per litre. 

Human serum analysis Eluent A (0.05 M perchloric acid ACN = 60 40)/eluent B (0.05 M perchloric acid ... 

Typical stationary phases include the following polyvinylpyrrolidone (PVP) coated silica sorbents, monodisperse non-porous silica columns with surface bound amides or ethers and composite agarose and polyacrylamide gels. The eluent normally consists of salts at concentrations greater than 1.0 M. Typical salts include sodium phosphate, sodium sulfate and ammonium sulfate, and organic acid salts like monosodium glutamate. Protein retention is stronger with salts that increase surface tension like phosphates, sulfates, citrates, which are solvated in water than with salts such as perchlorates and thiocyanates and the like. 

Examples using HPLC include Spherisorb S5W silica column (4.9 mm i.d. x 125 mm), eluent - methanolic ammonium perchlorate (10 mM) plus 1 ml/L methanolic NaOH (0.1M), UV detection (254 nm), no electrochemical response, relative Rt reported 3 pBondapak C18 column, eluent -methanokphosphate buffer (2 3), ratio of UV absorbance (254 and 280 nm) measured, relative Rt reported 4 pBondapak RP-18 column (20 x 0.6 cm i.d.), eluent - methanokwater (7 3), UV detection (267 nm), Rt 5.3 min21 Zorbax C8 column, gradient elution using 0.1% H3PO4 and 0.1% H3P04./10% water in... 

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