Abstract: Method of optically analysing a sample by directing one or more frequencies of electromagnetic radiation (EMR) through a sample and onto a partially reflective surface that allows EMR directed thereon to be both reflected and transmitted. The reflected EMR is directed back through the sample such that the pathlength through the sample is different for the transmitted EMR and reflected EMR. The transmitted EMR and reflected EMP are both detected by one or more detectors. The optical absorbance of the sample at the one or more wavelengths of EMR is calculated from the difference between the transmitted EMR and reflected EMR.

Abstract: The present invention relates to a sealable cell for measuring a liquid sample comprising a spectroscopic probe and a removable cap that can accommodate at least the head of the probe, wherein the internal wall of the cap comprises one or more grooves which are disposed so as to allow a liquid sample to enter the head of the probe and air to escape from the head of the probe to enable improved spectra to be obtained.

Abstract: A method for the on-line analysis of a process stream, which process stream is a feedstream to or an exit stream from a steam reformer, which process stream has a temperature of at least 200° C., the components of which process stream are in the vapour phase, which method comprises: (a) taking a slipstream from the process stream; (b) cooling the slipstream to a temperature above its dew point; (c) analysing the cooled slipstream by near infra-red (NIR) spectroscopy to obtain a spectrum characterising NIR-absorbing components of the process stream; and (d) correlating the spectrum obtained to established calibration models from NIR spectroscopy using chemometric techniques to determine the concentration of, and/or to determine the partial pressure of one or more of the NIR-absorbing components of the process stream.

Abstract: Sealable cell for obtaining a reflectance spectrum of a liquid sample using a spectroscopic probe having a removable cap wherein the internal wall of the cap comprises at least one groove that allows air to escape from the head of the probe and a liquid sample held within the cap so that accurate spectra can be obtained.

Abstract: The present invention relates to a sealable cell for measuring a liquid sample comprising a spectroscopic probe and a removable cap that can accommodate at least the head of the probe, wherein the internal wall of the cap comprises one or more grooves which are disposed so as to allow a liquid sample to enter the head of the probe and air to escape from the head of the probe to enable improved spectra to be obtained.

Abstract: A process for measuring the NIR spectrum of a sample using a demountable NIR transmission cell of pathlength 2.5 mm or less, said process comprising: (a) measuring the etalon fringes that arise when NIR light passes through the NIR cell in the absence of a liquid sample, (b) using this to calculate the pathlength of the NIR cell (c) introducing the sample to be analyzed in to the NIR cell, and (d) measuring the NIR spectrum of the sample.

Abstract: The present invention relates to a sealable cell for obtaining a reflectance spectrum of a liquid sample using a spectroscopic probe having a removable cap characterised in that the internal wall of the cap comprises at least one groove that allows air to escape from between the head of the probe and a liquid sample held within the cap so that accurate spectra can be obtained.

Abstract: In a process for the production of vinyl acetate by reacting ethylene, acetic acid and an oxygen-containing gas in a reactor to produce a process stream which is removed from the reactor as an outlet stream, the process is improved by maintaining the oxygen concentration of the outlet stream at or near its flammability limit.