Photo-response assisted enantiomer separations on an azobenzene-modified gamma-cyclodextrin stationary phase in micro-HPLC.
The photo-responses of the retention and enantioseparation of several optical isomers were evaluated using an azobenzene-modified gamma-cyclodextrin stationary phase (Az gamma-CDSP) in micro-HPLC. UV light irradiation induced a decrease in the retention and the chiral selectivity for N-(3,5-dinitrobenzoyl)-1-phenylethylamine (DNBPEA) and N-(3,5-dinitrobenzoyl)-1-(1-naphtylethyl)amine (DNBNEA), while an increase was induced for dansylphenylalanine (DnsPhe) using a mixture of methanol and aqueous phosphate buffer as the mobile phase. No changes in the retention and the enantiomer separation of benzoin were observed with UV light irradiation. The retention behaviors were recovered by visible-light irradiation. It was speculated that the main factor of the change in the retention behavior was a change in the pi-pi interaction due to the azobenzene moiety of the stationary phase with photo-irradiation. Comparing the retention behavior before and after UV light irradiation, a suitable condition for obtaining a better resolution and enantiomer separation would be chosen using Az gamma-CDSP.
Recent Advances in Materials for Separation
高速液体クロマトグラフィー（HPLC）及びキャピラリー電気クロマトグラフィー（CEC）用の充填剤に関する最近の進歩についてまとめた．HPLC用充填剤としては，依然としてシリカゲルやその化学修飾体が汎用されているが，これはシリカゲルが優れた分離能と機械的強度を有するからにほかならない．一方，酸や塩基に対するシリカゲルの化学的脆弱性を補うために，シリカゲル担体を化学的安定性の高いポリマーで被覆する方法や，有機又は無機ハイブリッド型シリカゲルを開発する取り組みが積極的に行われ，逆相系の充填剤として活用されている．チタニア，ジルコニアが有する化学的安定性と有機リン酸化合物に対する特異的な化学的親和性（ケモアフィニティー）には一段と関心が高まり，とりわけホスホプロテオーム解析では重用されるに至っている．温度感応性充填剤，光応答性充填剤，バイオアフィニティー担体，モレキュラーインプリントポリマー，分子形状認識型充填剤など，各種機能性充填剤についても注目すべき多くの報告があり，それらが示す高度な分離能や選択性には興味をひかれる．なお，モノリスカラムの創案はカラムテクノロジーの一大革命であると評されているが，これについては既に多数の総説が発表されているので，本稿での扱いは必要最小限にとどめた．
Comparison of a Radiometric Procedure with Conventional Methods for Identification of Neisseria
A radiometric procedure was compared with the conventional cystine tryptic agar (CTA) sugar fermentation method for identification of Neisseria species. Four different ATCC cultures of Neisseria were identified by both procedures with identical results. The only difference noted was that the radiometric procedure required 3 h for completion, whereas the conventional CTA sugar method required overnight incubation. The radiometric procedure was also compared with the fluorescent antibody (FA) and CTA methods for identification of Neisseria gonorrhoeae. The organisms examined were gram-negative, oxidase-positive diplococci isolated from 49 clinical specimens sent to the laboratory for bacteriological analysis. Results obtained by both CTA and FA procedures were comparable. However, the radioisotope method appeared to be superior to the other two methods in that only one isolate identified as positive by both the CTA and FA methods was not identified radiometrically, whereas four isolates positive by the radiometric method were not identified by the other two procedures. Thus, a total of seven more positive identifications were made radiometrically than by either of the two other methods. All positive identifications were confirmed by a reference laboratory. These results indicate that the radiometric procedure is more rapid and reliable as compared with both the CTA and direct FA methods and, thus, may serve as a valuable addition to the methodology available for diagnostic microbiology.