Spectrometric determination of anionic surfactants in environmental waters based on anisole extraction of their bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) ion pairs.

A spectrometric method for the determination of anionic surfactants in environmental water samples using the [Co(III)-(5-Cl-PADAP)(2)](+) chromophore was technically improved for practical use. An anisole-extraction procedure was alternatively introduced and optimized in place of the earlier benzene-extraction procedure. The molar absorptivity for SDS found by the Co(III)-5-Cl-PADAP/anisole method was 72000 L mol(-1) cm(-1) at 560 nm, which was ca. 1.3-times higher than those by the Co(III)-5-Cl-PADAP/benzene method. The analytical sensitivity was almost independent of the kind of anionic surfactants. The calibration lines for SDS, LAS, and SSS were all linear between 1.0 × 10(-7) and 1.0 × 10(-5) mol L(-1) with acceptable r(2) values of 0.9998, 0.9995, and 0.9999, respectively. The method was applied to the analyses of river, well, and seawater samples, providing the compatible results by means of the standard-addition method. In the case of seawater, a phase-washing treatment of the extracted species using dilute HCl was effective to decrease the high blank absorbance. The Co(III)-5-Cl-PADAP/anisole method, showing no glass-adsorption problem, is more advantageous than the methylene-blue and ethyl-violet methods.

Simultaneous determination of silicate and phosphate in environmental waters using pre-column derivatization ion-pair liquid chromatography.

A highly sensitive HPLC method for the simultaneous determination of soluble silicate and phosphate in environmental waters was developed, using ion-pair liquid chromatography preceded by the formation of their yellow alpha-heteropolymolybdates. The moderate-pH mobile phase enabled to use a highly efficient reversed-phase silica column. The pre-column coloring reactions at moderate-pH were reproducible for both silicate and phosphate in all quantification ranges with R.S.D.s less than 2% and 5%, respectively. The linear calibration lines between concentrations (mg-SiO(2)/L and mg-PO(4)/L) and peak area intensities were obtained for silicate and phosphate both with acceptable determination coefficients (r(2)) of 0.9999. The limits of determination for both analytes were 0.007 mg-SiO(2)/L and 0.003 mg-PO(4)/L, which were calculated theoretically using 10sigma/slope. The four-digit dynamic ranges were obtained for 0.007-10mg-SiO(2)/L and 0.003-20mg-PO(4)/L. The developed method was applied for the analysis of tap water, river water, coastal seawater, well water, hot-spring water, commercial mineral water, and laboratory water. The results were very reasonable and acceptable from the environmental viewpoints, which were well correlated with those confirmed by the molybdenum-blue spectrophotometry.

Simultaneous determination of creatinine, creatine, and UV-absorbing amino acids using dual-mode gradient low-capacity cation-exchange chromatography.

A simple and versatile cation-exchange chromatography technique for the simultaneous determination of urinary creatinine (Cre), creatine (Crn), methionine (Met), tyrosine (Tyr), phenylalanine (Phe), histidine (His), and tryptophan (Trp) was developed. A novel low-capacity cation-exchange column packed with a newly developed sulfoacylated hypercross-linked macroreticular polystyrene-divinylbenzene resin, referred to as TMR-A/75 (capacity: 75 microequiv/column), was successfully used with a binary dual-mode gradient eluting system. Two solvents, (A) 25 mM phosphoric acid-methanol (30:70, v/v) and (B) 25 mM disodium hydrogenphosphate-methanol (30:70, v/v) were pumped through the column by programming solvent delivery ratios as 0 to 5 min: A-B (55:45, pH 3.6); 5-21 min: A-B (49:51, pH 5.3); and 21-35 min: A-B (55:45, pH 3.6). The flow rate was simultaneously time-programmed to be 0.6 mL/min from 0 to 19 min and to be 1.0 mL/min from 19 to 35 min. This eluting system could permit the use of the UV detection at 210 nm. The analytes, Crn, Met, Tyr, His, Cre, Phe, and Trp, were well separated in this order in 27 min with minimum resolution of approximately 2, and the cycle time was about 35 min. Retention time of each analyte was very reproducible with relative standard deviations (RSDs) between 0.05 and 0.38% (n = 5). The peak area responses were also reproducible with RSDs between 0.74 and 2.24% (n = 5). Calibration lines based on area data were linear from 1 to 1000 microM with r2 values of 0.9998 (Crn), 0.9998 (Met), 0.9999 (Tyr), 0.9999 (His), 1.0000 (Cre), 1.0000 (Phe), and 0.9999 (Trp). The method was applicable to the screening and/or chemical diagnosis of inherited metabolic disorders such as phenylketonuria (PKU), tyrosinemia, and Lowe syndrome. The creatinine ratios of diagnostic markers (microM/microM Cre) were easily determined. The Phe/Cre ratios for five urines from patients with PKU ranged from 0.162 to 0.521, and the Tyr/Cre ratio for tyrosinemia was 0.147. The ratios of Tyr/Cre, Phe/Cre, and Trp/Cre for Lowe syndrome were 0.497, 0.321, and 0.495, respectively. In contrast, the creatinine ratios for healthy newborns showed one digit lower than those for patients did. The developed method is very practical and can provide useful information and results for the clinical or biomedical researches with low analytical run costs.

Simultaneous determination of urinary creatinine and UV-absorbing amino acids using a novel low-capacity cation-exchange chromatography for the screening of inborn errors of metabolism.

A simple and versatile low-capacity cation-exchange chromatography system for the simultaneous determination of creatinine and UV-absorbing amino acids was developed. The separation column was packed with a newly developed low-capacity sulfoacylated macro-porous polystyrene-divinylbenzene resin selective for amino-acid cations. Urinary creatinine, creatine, tyrosine, histidine, phenylalanine, and tryptophan were simultaneously separated and determined by an isocratic elution with phosphate/acetonitrile eluent in 25 min. Relative standard deviations (R.S.D.) of the retention times for the analytes were between 0.28 and 1.06%. R.S.D. of peak area responses for the analytes were between 0.75 and 3.51%. The r(2) values for the calibration lines were between 0.9994 and 0.9999. The method could provide the creatinine ratios for the analytes, and was applicable to the screening and/or chemical diagnosis of several inherited disorders of amino-acid metabolism such as phenylketonuria (PKU).

Low-capacity cation-exchange chromatography of amino acids using a novel sulfoacylated macroreticular polystyrene-divinylbenzene column with binary gradient elution.

This paper describes a versatile technique for amino-acid separation using a novel low-capacity sulfoacylated macroreticular polystyrene-divinylbenzene cation-exchange column with a simple binary high-pressure pH gradient elution. Proteinic 16 amino acids were well separated within 50 min using a H3PO4/Na2HPO4-CH3CN eluent system, and the cycle time was about 70 min. The chromatography with postcolumn OPA fluorescent detection was reproducible with RSDs less than 1% for retention times, and was quantitative with RSDs less than 5% for area responses. A linear regression line with an r2 value above 0.9990 was obtained for each analyte in concentration from 0.1 to 10 microM by 20 microL injection. The method was applicable to the separation and detection of urinary diagnostic amino acid due to inborn errors of metabolism, such as phenylketonuria. The analytical costs would be decreased by using the proposed method.

Identification of unknown surfactants using electrospray mass spectrometry and NMR spectroscopy preceded by liquid ionization mass spectrometry.

Commercially available but completely unknown surfactants used in the tin-lead plating industry were successfully identified by using electrospray mass spectrometry and NMR spectroscopy techniques, preceded by liquid ionization mass spectrometry used to obtain the preliminary information. The mass spectral data suggested that ethoxylated nonionic surfactants having a homologous distribution of molecular weights like 520, 564, 608, 652, 696, etc. were present. The NMR data suggested the presence of two aromatic rings and a quaternary carbon for the hydrophobe moiety instead of the well-known alkyl chains or alkylphenols. The unknown surfactants were finally concluded to be novel nonionic 4-(alpha,alpha-dimethylbenzyl)-phenol ethoxylates.

Sulfoacylated macro-porous polystyrene-divinylbenzene low-capacity cation exchanger selective for amino acids.

A low-capacity cation-exchange column was newly developed for the separation of amino acids. A highly cross-linked macro-porous polystyrene-divinylbenzene co-polymer was functionalized by a sulfoacylation reaction. The exchange capacity was controllable at the acylation step. The capacity between 55 and 60 micromol/column was adequate for the practical separations in acceptable retention times. The 5-microm base polymers having average pore diameters smaller than 3 nm gave satisfactory results, and those having 1.5-nm pore was most favorable. Several isocratic elution conditions at different pH values adjusted by phosphate buffer of mM order with or without acetonitrile could provide good separations for individual classes of amino acids, i.e., acidic, neutral, hydrophobic, and basic groups. The results provided fundamental data for constructing gradient elution systems required for the simultaneous separation of protein amino acids.

Elucidation study of thermal decomposition products of human serum albumin using liquid ionization mass spectrometry.

The origin of the intense but unknown peaks at m/z 235 observed in liquid ionization (LI) mass spectra of middle ear effusion and serum was investigated by using related standard compounds and the collision induced dissociation techniques. The ions were observed as the base peaks in mass spectra of the aqueous fractions of middle ear effusion and serum after chloroform extraction and in those of authentic human serum albumin (HSA) too. The ions commonly observed in serous fluids could be estimated as tyrosil-valil interchain immonium ions arising from thermal decomposition of HSA during the measurement. Such thermally stable interchain immonium ions, also observed in some oligopeptides having Val-Tyr sequence as their fragment ions, are likely to be characteristic ions for large protein molecules.