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The analytical methods for the determination of inorganic anions by water elution ion chromatography using a zwitterionic column (C14SB-coated column) have been explored, where pure water was used as the mobile phase. In the present ion chromatography, the complicated peaks derived from various 'ion pairs' appeared on the chromatogram when the sample solution contained several kinds of cations and anions. The chromatograms with the complicated peaks were simplified by using a preconditioning cation-exchange column. In the preconditioning column, various kinds of countercations of the analyte anions were converted to a particular kind of common cation, and thus all the analyte anions were separated as the common cation form. The more effective separation was achieved by converting to a divalent cation ([Mg.sup.2+]) form than a monovalent cation ([Na.sup.+]) form, because the anions paired with the divalent cation provided longer elution times than those paired with the monovalent cation. All the analyte anions separated as the common cation form were simply determined from their calibration curves drawn from conductivity detection. In addition, the counterionic determination of the anions was also attempted by using ICP-AES. The analyte anions were determined by measuring their countercations with ICPAES, where the calibration curve of the countercation measured by ICP-AES could be used.

Partitioning behaviors of analyte cations and anions in 'electrostatic ion chromatography (electrostatic IC)' were investigated. Detectors of ICP-AES (inductively coupled plasma atomic emission spectrometry), UV absorption, and conductivity were connected on-line to the electrostatic IC and used for the selective detection of cations, anions, and 'ion-pairing-like forms' (both cations and anions), respectively. When a mixed electrolytic aqueous solution containing cations A, C, ..., Y, and anions B, D, ..., Z, was passed through the electrostatic IC column, the analyte ions, which dissociated from the original salts AB, CD, ..., and YZ, were each redistributed and forced into a new state. This new state was termed an ion-pairing-like form because of the simultaneous electrostatic attraction and repulsion interactions. The same species of anion or cation are found in more than one ion-pairing-like form; however, they occur in different volumes. What is more, each ion-pairing-like form has a different priority of formation. Born's equation was used to evaluate that priority. Retention time of the ion-pairing-like form was dependent on the species of the anion and the charge of the cation. All ion-pairing-like forms can be simultaneously separated with the exception of those having the same anion species as well as the same cation charge. Ion chromatography using a strong/strong positive/negative charged zwitterionic stationary phase with pure water as the mobile phase was termed electrostatic ion chromatography.

Ion chromatography using 'strong/strong' charged zwitterionic micellar-coated stationary phase with pure water as the mobile phase has been investigated for the separation of inorganic solutes and organic zwitterionic solutes. Retention mechanisms of the zwitterionic charged stationary phase in ion chromatography have also been investigated using a conductivity detector. For inorganic analytes, anions and their countercations are always eluted together. The retention times of inorganic solutes are only dependent on the anions. According to experimental results, we suggest that analyte anions and their countercations combine to make 'ion-pairing-like' forms and are separated by the simultaneous electrostatic attraction and repulsion interactions between the zwitterionic charged stationary phase, analyte anion, and its countercation. The formation of the simultaneous electrostatic attraction and repulsion interactions between the same and opposite charges can also be used to explain the retention behavior involved in the separation of organic zwitterionic solutes by the strong/strong charged zwitterionic stationary phase with pure water as the mobile phase. The present system was used for the rapid determination of iodide and thiocyanate in human saliva samples.

Trace amounts of copper and iron in volatile metals such as zinc or lead may be detected through plasma atomic emission spectrometry by directly inserting the sample into the plasma with a graphite cup. Lack of azeotropicity and the wide gap in boiling points between analyte and matrix metals help minimize chemical and spectral interferences. Data resolution is achieved by peak integration, using standard solutions as reference, to compensate for delayed atomization of copper and iron in metal matrix compared to those in solution. Except for one sample in the lead matrix,readings from the direct insertion method correspond with certified sample values.

A single reversed-phase ODS (octadecyl silica) column coated with taurine-conjugated bile salt micelles has been investigated for simultaneous separation of inorganic cations and anions. Under acidic conditions in the separation column, taurine-conjugated bile salts are protonated; therefore, the stationary phase coated with taurine-conjugated bile micelles exists as a 'weak/strong'-charged zwitterionic stationary phase (H+ and SO3-). The weak/strong-charged zwitterionic stationary phase provides a new retention mechanism which is different from conventional ion chromatography in that both positive and negative charges are close together in a single molecule, resulting in simultaneous electrostatic attraction and repulsion of the analyte ions. Also, the stronger negative charge (sulfonate) of the stationary phase works as a cation-exchange site at the same time. The combined effects of cation-exchange and simultaneous electrostatic repulsion/attraction interactions were successfully used in ion chromatography for the simultaneous separation of inorganic cations and anions.