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A fully-automated HPLC system for simultaneous determination of three pesticides, simazine, thiram and thiobencarb, in tap water was developed.A test tap water was made up in a solution of 2mM sodium ascorbate and 1mM EDTA in order to prevent the decomposition of thiram and thiobencarb from residual chroline and metal ions. Three ml of the tap water injected by the auto sampler was passed through an enrichment column, where the pesticides were trapped quantitatively. The pesticides were then flushed from the column onto an analytic column, where the separation was achieved, and they were measured by the UV detector. The recoveries of simazine (0.3μg/l), thiram (0.6μg/l) and thiobencarb (1.0μg/l) spiked to 7 tap water samples were 93-100%, 92-98% and 81-88%, respectively. It may be possible that many samples are continuously analyzed within a running time of 30minutes by the proposed system. Therefore, it is suggested that the analytical system is effective for daily assay of simazine, thiram and thiobencarb in tap water as a screening method.

Previously, we developed a novel detector, a polarized photometric detector for optically active compounds, where two polarizers are set on either side of the UV-visible absorbance detector flow cell. In this paper, we present theoretical considerations on this method with several equations. If the inclined angle of the second polarizer is defined as alpha (left when alpha > 0 degree), the following equation is obtained: delta Abs = 2 log e.tan alpha.beta, where delta Abs is the change in absorbance and beta (magnitude of beta << alpha) is the angle of rotation of light passing through the cell containing the optically active compound. This equation suggests that delta Abs is proportional to the analyte concentration and that the dextro- and laevorotatory compounds are detected as positive and negative absorbance changes, respectively. The theoretical maximum signal to noise (S/N) ratio is obtained when alpha = 45 degrees (= 0.8 rad) and the smallest detection limit is 5 x 10(-5) degrees (S/N = 3) when the path length of the flow cell is 10 mm. This detector was successfully used in flow injection analysis (FIA) as well as HPLC for optically active compounds.

A high-performance liquid chromatographic method for determining the enantiomeric purity of malic and tartaric acids with the combined use of UV and polarized photometric detectors in series has been established, in which no physical separation of enantiomers is required. Complexation with molybdate significantly increases the specific rotation of these acids. Thus, coupling polarized photometric detection with anion-exchange chromatography using a molybdate solution as the eluent makes possible the highly sensitive detection of optically active analytes with the conventional system. The proposed method can detect synthetic racemic acids in adulterated fruit juices at the 5% level.

Multiple copper chlorophyll analogues were detected in the chewing gum product containing the copper chlorophyll dye using a HPLC apparatus with photodiode array detection. The main components among these analogues were assumed to be 10-hydroxy copper chlorophyll a and b by IR, FAB/mass and NMR spectrometry. Since these copper chlorophyll analogues were main components in the commercial food additive dye, "copper chlorophyll", it was clear that these analogues in the chewing gum product were carried over from this food additive. The 10-hydroxy pheophytins, which are precursors of these copper chlorophyll analogues, were detected from the extract of silkworm excreta, the original material of this dye. These copper chlorophyll analogues were possibly produced by the metalation reaction between the copper and the 10-hydroxy pheophytins which might be generated from the oxidation of pheophytins, like "allomerization reaction", during the process of the synthesis of the original material and its storage. It is possible that these analogues have already been the main components in the original dye.

The formation of a system peak in non-suppressed ion chromatography is related to the adsorption of undissociated eluent acid onto the functionalized resin surface. To clarify the elution behaviour of system peaks, a new method for determining the isotherms from the capacity factors of system peaks using low-pH eluents free from sodium ions was developed. The isotherms for adsorption of undissociated salicylic and phthalic acids as eluents onto an IC-Anion-PW column, measured by the present method, showed two-site biLangmuir correlations. The capacity factors of system peaks calculated from the equations based on these isotherms were in good agreement with those from actual chromatograms with the acidic eluent conditions.

飲料水への暫定基準が設定されているゴルフ場使用農薬30種類について, 塩素1μg/ml濃度で個々に分解実験を行った。農薬の塩素による分解を疑一次反応と仮定し, 速度定数と半減期を算出したところ, 農薬の種類により, 分解速度に大きな差がみられた。分解の速い農薬については, 浄水からの検出率が水道原水からのそれに比べ低いと推定される。厚生省が公表した調査報告は, 検出率に有意差があり, 本実験結果からの推定は支持された。ところで, 分解の速いイソフェンホス, ブタミホス, ベンスリドの有機リン農薬3種とチラムについて, それぞれ1モルを分解する塩素消費量は, 5, 7, 3及び30モルであった。なお, 有機リン農薬からは, オキソ体の生成が推定された。

In multiple eluent ion chromatography, the analyte elution behaviour still remains unclear. In this work, the inter-eluent selectivity coefficient was accurately determined by re-interpreting Hoover's model. Obtaining the inter-eluent selectivity coefficient was greatly simplified by introducing the concept of an “inter-eluent separation factor”. From the coefficient obtained, analyte capacity factors in polyprotic eluent systems can be estimated a priori. Moreover, this new factor permits the calculation of eluent species with different charges and, through stoichiometric simulation of the chromatogram, makes possible the a priori estimation of analyte peak intensities.

The washing effect of minced fish muscle on the degradation of polyphosphates (PP) in the salted meat paste (SMP) during the setting process was studied. Surimi MWO-MW4 were made from minced Walleye pollack muscle by washing 0-4 times with a buffer solution (pH 7.5). Aliquots of the SMP MWO-MW4, which were mixtures of surimi MWO-MW4, NaCl, and tripolyphosphate (P3), were incubated at 20°C. Degradations of P3 and pyrophosphate (P2) in the SMP during the setting process were determined. In the SMP MWO, P3 was rapidly degraded to P2 and P2 thus formed was also rapidly degraded to orthophosphate. As the number of washing times increased, the degradation rates of both P3 and P2 slowed down and P2 became hard to be degraded in SMP MW2-MW4. In order to determine the mechanism of this phenomenon, the amounts of tripolyphosphatase (P3ase), pyrophosphatase (P2ase) and magnesium (Mg) as an enzyme activator in surimi MWO-MW4 were measured. Along with the washings, P2ase and Mg were washed out from minced muscle, but P3ase was not. The decrease in Mg concentration suppressed P3ase activity in the SMP. Thus, repeated washing of minced muscle seemed to have an effect to degrade P3 and P2 in the SMP during the setting process.

HPLC using a large-volume injection technique has been developed to determine trace levels of pesticides in water. To prevent disturbance of the base line from excess water injected, a reversed-phase guard cartridge is substituted for an injection loop as an enrichment column. This procedure is applied to Asulam, N'-methoxycarbonyl sulfanylamide, one of the herbicides used in golf links. One milliliter of sample made up in a solution of 0.5 mM in cetyltrimethylammonium chloride is passed through the cartridge, where Asulam is trapped quantitatively. Asulam is then back flushed from the cartridge onto an analytical column, where the separation is achieved. Asulam below ppb level can be readily detected. The precision of the measurements, evaluated by the analysis of spiked samples, is 3.3% at 1 ppb level.

A simultaneous determination method for five organic acids in vinegar has been established by photometric ion chromatography. Both trace components (lactic, gluconic, succinic and pyroglutamic acids) and the major component (acetic acid) in vinegar were separated on a TSK gel IC-Anion-PW column with 0.45 mM o-aminobenzenesulfonic acid aqueous solution as an eluent. Their elutions were detected as positive peaks before the system peak, and a negative peak after that by a UV monitor. The sensitivities of trace components were enhanced by adjusting their elutions close to the system peak. The lowest detection limits were 10μM lactic acid, 5μM gluconic and succinic acids and 3μM pyroglutamic acid, respectively. The only pretreatment necessary was dilution of vinegar 100-fold with the eluent. The results obtained by the proposed method were in good agreement with those by the enzymatic one.

A method of high-performance liquid chromatography (HPLC) using post column reaction system has been established by us for the determination of polyphosphates (PP) in foods and PP contents in commercially available surimi-based products have also been examined. In the present investigation, behavior of PP during the manufacturing process of surimi-based products was studied. Surimi was made from Alaska pollack muscle washed twice with a buffer solution (pH 7.5). Aliquots of salted meat paste, which was a mixture of surimi, NaCl and tripolyphosphate (P3), were incubated under various conditions. After incubation, aliquots were homogenized with ice-cold 6% trichloroacetic acid and centrifuged. The super-natants obtained were applied to HPLC for the determination of PP. It was found that P3 was enzymatically degraded to pyrophosphate (P2) and orthophosphate (P1) in the salted meat paste during grinding and setting processes, but P2 was seldom degraded to P1. Optimal temperature, NaCl concentration, and pH of tripolyphosphatase (P3ase) activity in the salted meat paste were around 27°C, 6.0%, and 6.0, respectively. P3ase was rapidly heat-inactivated at temperatures above 35°C. Although thermal degradation of P3 occurred during heating process, the degree of degradation was much smaller than that by P3ase during grinding and setting processes.

ポストカラム反応法を用いたHPLCによる固体食品中のPPの分析法を検討し,次の結果を得た. (1) 分離カラムには親水性ビニルポリマに陰イオン交換基を結合したProtein Pak G-DEAEを,移動相には0.01M硝酸-硝酸ナトリウムを用い,硝酸ナトリウムの濃度グラジェント法でP 2～P 12を分離し, P 1に分解することなく鉄・スルポサリチル酸錯体と反応させて測定した. (2) 食品から氷冷した4% TCAでPPを抽出し,不溶物を除去するだけの簡単な操作でHPLC分析が可能であった. (3) チーズ及びかまぼこにP 2, P 3, P 4を添加し,回収率を測定したところ,それぞれ100.2, 98.0, 95.0及び98.0, 93.0, 90.0%であった. (4) 市販チーズからはP 2～P 9が検出され,総量は5.64～14.67g/kgであり,その組成はP 2が50%以上を占め, P 2～P 4で90%を超えた.かまぼこ,ちくわ,ソーセージ及びハムは,すべての検体からP 2が検出され,その割合は90%以上を占め, P 3が少量含まれるものもみられたが, P 4以上はいずれからも検出されなかった.

A photometric detector for an optically active compound is described in which two polarizers are set on both sides of the flow cell. When a nonchromophoric, optically active compound passes through the cell, the intensity of natural light transmitted through the polarizers and flow cell is changed. The detection of such a sample is possible photometrically. A large inclination angle between the polarizers increases the absorbance change and allows dextrorotatory and levorotatory to be differentiated. The direct HPLC/photometric detection of sugars is presented as an axample of this device.

An ion chromatographic separation with photometric detection using a chiral copper(II) complex as the eluent has been developed for the resolution of enantiomers of malic acid in commercially available apple juices. The results obtained by this method were in good agreement with those by an enzymatic method with separation by high-performance liquid chromatography.

In this paper, the authors demonstrate the determination of malate enantiomers by using a hydrophilic material-based anion exchange column and chiral copper(II)-tartrate complex as an eluent

A split-type flow cell for a polarized spectrophotometric detector (PPD), in which the column effluent is simultaneously passed through both the sample and reference sides, is described. The improvement in detection sensitivity in PPD with the use of this cell is discussed. Its utility as a universal polarimetric detector for HPLC for the detection of coloured amino acid–copper(II) complexes is shown. A new possibility for this cell in the gradient elution separation of glucose syrup is demonstrated.

In liquid chromatography with photodiode array detection, a number of approaches have been developed in chemometrics to determine an analyte of interest in the presence of one or more unknown compounds. So far, these techniques have required time-consuming data analysis programs, and are not suitable for routine analysis. A ‘derivative spectrum chromatogram’ is proposed as a new approach for resolving overlapped peaks in real time. This procedure is based on the following assumptions: (i) an absorption spectrum of an analyte with rounded humps changes to steep peaks by high-order derivatization; and (ii) the principle of superposition is valid for the derivative spectra of a sample mixture. The performance of this procedure is assessed with real data for the separation of pesticides by liquid chromatography.

Palatinose has attracted interest recently as a saccharide not inducing dental carries. Polarized photometric detection (PPD) is feasible by incorporating two polarizers into a conventional photometric detector, thus enabling the determination of optically active compounds such as palatinose in combination with high performance liquid chromatography (HPLC). A PPD system with a borate-form ligand-exchange column was highly specific for disaccharides. This specificity made the sample pretreatment easy. The extract from food was ultrafiltered through a Tosoh ULTRACENT-10 cartridge prior to HPLC injection. The lowest detection limit of palatinose was 0.03μmol.

A general model is proposed for interpreting the appearance of sample and system peaks in ion-exchange chromatography with photometric detection. In this theory, a changed fraction of organic acid in the mobile phase resulting from the ion-exchange process with a sample ion migrates through the column from plate to plate in accordance with the ionic and partition equilibria. This perturbation of UV-detectable components yields the sample and system peaks. Simulation of this theory by computer accounts well for the sample peaks observed in real ion chromatography. An equation expressing the sample response—capacity factor relationship at low mobile phase pH was derived.

A high-performance liquid chromatographic method using post column reaction system was established for the determination of polyphosphates (PP). Linear polyphosphates with the range of polymerization from 2 to 9 (P2-P9) could be separated on an anion exchange column, TSK GEL DEAE-5PW (Toyo Soda), with 0.01 M HNO3 containing NaNO3 as a mobile phase at flow rate of 1.0 ml/min, with a linear gradient in NaNO3 concentration at one hour intervals. PP were detected as the decrease of absorbance at 500 nm of ferric-sulfosalicylate complex by means of an on-line post column reaction at room temperature, with 0.5 mM FeCl3 containing 2.5 mM sulfosalicylic acid as reaction reagent at flow rate of 0.5 ml/min. The proposed method was applied to the analysis of 30 different commercial products of soft drinks. The pretreatment only necessary after mixing the sample with an equal volume of 0.01 M HNO3 was filtration through 0.45 μm pore size filter. P2-P6 (total 0.231 g/kg) and P2-P4 (0.070 g/kg) were found from 2 kinds of the samples, respectively. The determination limit was 0.02 m mol/kg for all of the PP.

An indirect photometric ion chromatographic method (PIC) using a conventional high performance liquid chromatograph system equipped with a UV detector was established for the determination of phytic acid (PA) in foods. PA could be determined on an anion exchange column, Shim-pack IC-A1 (Shimadzu), with 0.3mM naphthalene-1, 3, 6-trisulfonic acid trisodium salt (NTS) adjusted to pH 5.5 as the eluent. The eluate was monitored at 295nm.The sample, which had been extracted with 0.6N hydrogen chloride and neutralized with 0.1N sodium hydroxide, was applied to an anion exchange resin column (AG1-X4). PA fraction eluted with 2N hydrogen chloride was evaporated to dryness and dissolved in water. After filtration through a membrane (pore size; 0.45μm), 5-50μl of the filtrate was subjected to PIC.The recovery of PA from soybean, barley or wheat flour was in the range from 93.0 to 98.3%. The determination limit was 0.05g/kg. The highest PA content, 72.4-87.0g/kg, was observed with rice brans among various foods examined.

A method of isocratic high performance liquid chromatography (HPLC) using an ion-pair partition system was established for simultaneous determination of 11 food coal-tar dyes (FD: including Amaranth, R-2; Erythrosine, R-3; New Coccine, R-102; Phloxine, R-104; Rose Bengal, R-105; Acid Red, R-106; Tartrazine, Y-4; Sunset Yellow FCF, Y-5; Fast Green FCF, G-3; Brilliant Blue FCF, B-1 and Indigo Carmine, B-2).Conditions for HPLC analysis were as follows: column, Develosil ODS-5 (5μm, 4.6mm i. d. ×250mm); mobile phase, acetonitrile-0.05M sodium dihydrogen phosphate (3:2) containing 0.002M cetyltrimethylammonium chloride and 0.003M tetra-n-hexylammonium bromide, pH adjusted to 3.0 with phosphoric acid; column temperature, 50°C; flow rate, 1ml/min; detection wavelength, 254nm.Soft drinks were pretreated with polyamide column chromatography prior to HPLC analysis for FD. Recoveries of FD from soft drinks were over 89.0%. The detection limits were 0.05μg/g for R-106, B-2, Y-4 and Y-5, 0.10μg/g for B-1, R-2, R-3, R-102 and R-104, and 0.20μg/g for G-3 and R-105.This method is considered to be applicable for routine analysis of food coal-tar dyes.