Fourier transform near-infrared spectroscopy used for purity determination of rhein-L-arginine cocrystal (argirein).

A method is described using rapid and sensitive Fourier transform near-infrared spectroscopy (FT-NIRS) for the determination of rhein-L-arginine cocrystal (argirein). By mixing different values of argirein into different proportions with rhein and arginine, we obtained 41 batches of samples to deatermine. Partial least squares (PLS) regression was selected as the analysis type and standard normal variate (SNV) and original spectra were adopted for the spectral pretreatment. The correlation coefficient (R) of the calibration model was above 0.99 and the root mean square error of predictions (RMSEP) was under 0.012. The developed model was applied to 10 batches of known samples with satisfactory results. The established method is validated and can be applied to the intrinsic quality control of synthetic products and other cocrystals.

Direct identification of dyes in textiles by direct analysis in real time-time of flight mass spectrometry.

We present here a method requiring no sample preparation for direct identification of the organic dye compounds quercetin, indigotin, and alizarin in reference materials, in solution, and also in situ in dyed fibers by use of direct analysis in real time (DART) ionization and high-resolution time-of-flight mass spectrometry. Exact mass determinations on small samples of dyed textiles were completed in less than 1 min. With the ability to identify flavonoid, indigoid, and anthraquinone classes of dyes, this technique shows early promise as an additional analytical tool in the challenging analysis of organic dyes in rare cultural heritage materials and possesses the unique advantages of sensitivity and simplicity without the preparatory procedures required by other methods.

Multivariate standard addition method solved by net analyte signal calculation and rank annihilation factor analysis.

This article describes the use of the net analyte signal (NAS) concept and rank annihilation factor analysis (RAFA) for building two different multivariate standard addition models called "SANAS" and "SARAF." In the former, by the definition of a new subspace, the NAS vector of the analyte of interest in an unknown sample as well as the NAS vectors of samples spiked with various amounts of the standard solutions are calculated and then their Euclidean norms are plotted against the concentration of added standard. In this way, a simple linear standard addition graph similar to that in univariate calibration is obtained, from which the concentration of the analyte in the unknown sample and the analytical figures of merit are readily calculated. In the SARAF method, the concentration of the analyte in the unknown sample is varied iteratively until the contribution of the analyte in the response data matrix is completely annihilated. The proposed methods were evaluated by analyzing simulated absorbance data as well as by the analysis of two indicators in synthetic matrices as experimental data. The resultant predicted concentrations of unknown samples showed that the SANAS and SARAF methods both produced accurate results with relative errors of prediction lower than 5% in most cases.

Certification procedures for nuclear fast red (Kernechtrot), CI 60760.

Nuclear fast red (CI 60760), also known as Kernechtrot, is commonly used in conjunction with an excess of aluminum ions as a red nuclear counterstain following histochemical procedures that yield blue products. The dye has also been used as a histochemical and colorimetric reagent for calcium. Unsatisfactory samples of nuclear fast red are encountered occasionally, and confusion has resulted from applying the name of the dye to neutral red (CI 50040), an unrelated compound with different properties. Tests for the identity and performance of nuclear fast red have been developed in the laboratory of the Biological Stain Commission. The Commission will now accept samples submitted by vendors for certification. We describe here the spectrophotometric, chromatographic and biological staining methods that are used to identify and test nuclear fast red.

[Sennosides Reference Standard (Control 951) of the National Institute of Health Sciences].

The "Sennosides Reference Standard (Control 951)" was prepared, which is intended to be used for the fluorophotometric assay of sennosides content in the preparation of "Sennosides". In this assay hydroxylated mono- and dianthraquinone glucosides are chelated with boric acid, and the fluorescence intensity of the chelate is determined against that of the Reference Standard (RS). In the establishment of this RS, sennosides content in the candidate material must be determined accurately by fluorophotometry. The Sennoside AB for assay, prepared as an equimolar mixture of the purified sennoside A and Sennoside B, was used as the RS for the fluorophotometry. Based on the above concept, sennosides content in the candidate was determined as calcium salts to be 60.1 +/- 1.6% by the fluorophotometry. Thus the sennosides content of this Sennosides RS was certified to be 60%. Separately, contents of Sennoside A (SA) and Sennoside B (SB) in this candidate were determined by using HPLC. As a result, the sum of SA and SB was estimated to be 38% as free acids. Thus it was suggested that about 20% of dianthraquinone glucosides other than SA and SB and anthraquinone glucosides may be included in this Sennoside RS as free acids. Analytical results on the USP Sennosides RS were also shown and discussed, compared with the present Sennosides RS.

[Substantiation of group MPEL for dispersive anthraquinone dyes]. / K obosnovaniiu gruppovoi PDK dispersnykh antrakhinonovykh krasitelei.

The article presents results of the toxicological studies of 65 replaced anthraquinones: amino-, diamino-, haloido-, hydro- and oxianthraquinones. A similar polytropic toxic action was identified. MACs for anthraquinones, alpha-aminoanthraquinones and K-type dispersal dye-stuff were established at 5 mg/m3. The toxicity properties of 11 other dispersal dye-stuffs with anthraquinone and NF disperser were studied. Similarity in the toxic properties of the dispersal dye-stuffs and those of the earlier standardized anthraquinone derivatives were established. The group MACs for the pigment and NF disperser containing dispersal anthraquinone dye-stuffs at 5 mg/m3 was established and subsequently formally adopted. A possibility of chemical assessment of dye-stuff dust concentrations against NF disperser (MAC at 2 mg/m3) was taken into account.