Narrow-bore liquid chromatography with multichannel detection in paediatric biochemistry: Analysis of phenylalanine and tyrosine in phenylketonuria

Summary In paediatric biochemistry, the analysis of drugs and endogenous compounds in preterm or low-birth weight neonates presents particular analytical problems. Sensitive techniques with small sample capacity are essential and in this context, narrow-bore (1–2mm) LC columns, coupled with appropriate low-volume detector cells and connections to reduce band dispersion, have been shown to offer significant advantages. By comparison with conventional columns an increase in sensitivity by a factor ofca. 2 can be achieved. The combination of narrow-bore columns and rapid-scanning UV detectors in reversed-phase LC enables the spectral information to be used for both peak recognition and homogeneity validation. Furthermore, “diode bunching” in the wavelength domain leads to a further two-fold increase in sensitivity. This combination of column and detector technology has been utilised in the design of a sensitive serum micro-assay of the essential aromatic amino acids in paediatric samples, capable of being used with 500nl sample, sensitive to 13pg phenylalanine and 9pg tyrosine and linear over the requisite therapeutic range.     

High resolution recycle gas chromatography with off-line flame ionization detection

Preliminary results of a recycle system employing fused silica capillary columns are discussed. The unit, which can be operated with a pre-column for multidimensional GC, utilizes continuous stream splitting for off-line flame ionization detection. Commercially available rotary valves were used for recirculation of the chromatographic zone between column loops. Adsorptive activity, which is shown to be additive, is a serious limitation in the analysis of polar compounds. The successful application of recycle chromatography to increase resolution on non-polar mixtures is demonstrated.     

Parallel and serial dual electrode detectors for capillary electrophoresis

Application of parallel and serial dual electrode detectors for capillary electrophoresis was first described. In parallel dual electrode approach, two 100 μm-diameter Cu disks arranged side by side were used as the dual working electrode for the simultaneous determination of a mixture of carbohydrates and amino acids. In serial dual electrode approach, two working electrodes were arranged in a disk-ring manner for the simultaneous determination of both cysteine and cystine; the disk electrode was Hg/Au serving as the upstream electrode, the ring electrode was 5% CoPC carbon paste serving as the downstream electrode.     

Detector quantum efficiency: An important parameter for FT-IR spectroscopy

Spectral detectivities (D ^*()) are commonly used to characterize the sensitivity of infrared detectors, but for most spectroscopic purposes they are very misleading.For photon detectorsspectral detector quantum efficiencies ( _q ()) are needed in order to calculate the (S/N) ratio for the photon-noise limited situation. An equation to calculate _q(#x03C3;) fromD ^*() values is presented. The results for some common IR-detectors are surprising.As an application for the use of _q () values theS/N ratio of an FT-IR spectrum from an optimized FTS instrument under photon-limited conditions is given.     

集成芯片毛细管电泳电化学检测系统

研制了一种新颖的集成芯片毛细管电泳电化学检测装置。此装置基于柱末安培检测法，将检测池集成芯片上，以自制的30μmPt微盘电极为工作电极，在几十年秒钟内实现了多巴胺、5－羟色胺和肾上腺素三种神经递质的快速分离检测。     

Effects of hydrocarbon quenching in gas chromatography when using the flame photometric detector

Summary The long time retardation of the main hydrocarbon peak in the chimney of the flame photometric detector greatly reduces the responses of later-eluting sulfur compounds. In the absence of hydrocarbons in the flame, the slope (s) of the log I vs. log [S] plot (where I is the sulfur response and [S] is the sulfur concentration in the sample) is of the highest value and is constant for all experimental conditions tested. Flame hydrocarbons cause the s value to decrease, and this is dependent on the oxygen to hydrogen ratio in the flame (O/H) and, under certain conditions, also on the sulfur to carbon ratio (S/C) of the sample. The abnormalities observed in the determination of methyl thiol in natural gas are explained on the basis of the present study.     

高效液相色谱-蒸发光散射检测器测定五种甾醇含量

建立了一种采用高效液相色谱－蒸发光散射检测器分离、测定五种甾醇含量的方法。该方法采用Supecol Discovery C18色谱柱，以甲醇作流动相，在75－5920ng/L范围内，甾醇峰面积的对数值与其含量对数值间有良好的线性关系，相关系数r的0.9983以上，相对标准偏差RSD小于0.45%，甾醇的平均回收率为98.3%－101％。该法简便，快速，准确可靠。     

HPLC determination of catabolic amines in silage using their dansyl derivatives and an electrochemical detector

Summary The use of the electrochemical detector (EC) in the high performance liquid chromatography (HPLC) of dansyl derivatives of biogenic amines is reported. Isocratic and gradient elution patterns of synthetic mixtures of putrescine, cadaverine, 1,6-diaminohexane, tryptamine, histamine, tyramine, spermine and spermidine on a reversed phase column are shown. Hydrodynamic voltammograms of standard compounds are presented. The detection limits of the EC are compared with those of ultraviolet and spectrofluorimetric detectors. A chromatographic profile of amines from the proteolytic catabolism of maize silage byClostridia is shown.Presented at the 17th International Symposium on Chromatography, September 25–30, 1988, Vienna, Austria.     

以多孔碳毡为工作电极的流动注射库仑检测器的研究及应用

本文设计了一个以多孔碳毡为工作电极的库化检测器并将其于用流动注射分析,以抗坏血酸、氢醌,没食子酸及二氧化硫为电活性物质检验该检测器的电化学特性。详细地研究了该检测器的库仑转换效率,选择性,线性范围,检测限及质量转移系数,并将该检测器作为双检测器流动注射分析系统中的“清除”电解池,用于酒中二氧化硫的测定,其结果与常规的吹气－氧化法非常吻合。