Abstract: For a baseline of instrumental output containing a signal and noise considered to be a stationary process, a calculation section 22 calculates an autocorrelation function or an autocovariance function of the baseline, and a statistical quantity of the baseline, based on the baseline of the instrumental output. A precision evaluation section 24 evaluates the standard deviation or the variance of the measurement values based on the autocorrelation function or the autocovariance function of the baseline calculated by the calculation section 22, and the statistical quantity of the baseline. The precision of the measurement values of the instrumental output can thereby be evaluated with high precision.

Abstract: In a process for producing a semipermeable composite membrane which comprises forming on a microporous substrate a thin layer of a polymeric material comprising a polyamino polymer containing at least 1 milliequivalent, per gram of the polymer in the dry state, of active amino groups selected from primary amino groups and secondary amino groups, and thereafter interfacially crosslinking a surface portion of said thin layer with a crosslinking agent having at least two functional groups (a) capable of easily reacting with either the primary or secondary amino groups or both in said polymer; the improvement wherein(1) said polymeric material contains dispersed therein a polyfunctional compound having at least two functional groups (b) substantially incapable of reacting with the primary or secondary amino groups in said polymer at a temperature at which the interfacial crosslinking is carried out, but capable of reacting easily with either the primary or secondary amino groups or both in said polymer at a tempe

Abstract: An amphoteric ion-permeable composite membrane composed of a microporous substrate, and supported on the substrate, a thin amphoteric ion-exchange film formed of an active amino group-containing polymer which has been interfacially crosslinked at least at the surface portion of the thin film, said membrane being produced by forming a thin layer comprising an active amino group-containing polymer containing 1.0 to 23 milliequivalents/g, as amino equivalent, of an active amino group selected from primary and secondary amino groups and 0 to 18 milliequivalents/g, as amino equivalent, of a tertiary amino group and/or an ammonium salt group per molecule with the total amino content thereof being in the range of 2.

Abstract: A semipermeable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of a microporous substrate, the polymeric material being prepared by crosslinking a soluble polymer containing at least 30 mole % of a recurring unit of the formula ##STR1## wherein all symbols are as defined herein, and having at least 0.5 milliequivalent, per gram of said polymer, of an amino group containing 1 or 2 active hydrogen atoms, with a polyfunctional compound containing at least two functional groups capable of reacting with the amino group having 1 or 2 active hydrogen atoms; and a process for preparing the same. The semipermeable composite membrane of this invention is especially useful for desalination of saline or brackish water by reverse osmosis.

Abstract: A semipermeable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of a microporous substrate, said polymeric material being prepared by crosslinking a soluble polymer containing at least 30 mole % of a recurring unit of the formula ##STR1## wherein all symbols are as defined in claim 1, and having at least 0.2 milliequivalent, per gram of said polymer, of an amino group containing 1 or 2 active hydrogen atoms, with a polyfunctional compound containing at least two functional groups capable of reacting with the amino group having 1 or 2 active hydrogen atoms; and a process for preparing the same. The semipermeable composite membrane of this invention is especially useful for desalination of saline or brackish water by reverse osmosis.

Abstract: A permselective membrane comprising a thin permselective film of a polymeric material, said polymeric material being prepared by cross-linking a polyaddition product between a polyepoxy compound and a polyamino compound having at least two amino groups capable of reacting with epoxy groups with a polyfunctional compound selected from the group consisting of aromatic, heterocyclic and alicyclic compounds containing at least two functional groups selected from acid halide, sulfonyl halide, isocyanate and acid anhydride groups; and a process for producing the same. The permselective membrane of this invention is especially useful for desalination of saline or brackish water by reverse osmosis.

Abstract: A process and composition for producing a permselective composite membrane. The process comprises dissolving a specified imidazolone ring-containing aromatic polymer in an aqueous liquid medium containing a water-miscible amine having a pKa of more than 5.0 in a concentration of at least 5% by weight, coating the polymer solution on a microporous substrate, and drying the coating to form an ultrathin film on the substrate. The permselective composite membrane obtained is especially useful as a reverse osomsis membrane.

Abstract: A semipermeable composite membrane comprising a thin semipermeable film of a polymeric material deposited on one side of the microporous substrate, said polymeric material being prepared by interfacial crosslinking of a polymer containing a recurring unit of the formula ##STR1## wherein each of R.sub.1 and R.sub.2 represents a hydrogen atom or a methyl group, and W.sub.1 represents a direct bonding or a sulfonyl group (--SO.sub.2 --), with a polyfunctional compound containing at least two functional groups selected from acid halide, sulfonyl halide, isocyanate, N-haloformyl, haloformate and acid anhydride groups; and a process for producing the same. The semipermeable composite membrane of this invention is especially useful for desalination of saline or brackish water by reverse osmosis.