Use of laser analyser LEA S 500 for analyzing the chemical composition of materials

Results are presented for analyzing the composition of various materials (both conducting and non-conducting) obtained in an atomic-emission spectrometer with a laser source for spectrum excitation. The possibility is confirmed of using a laser analyzer LEA S 500 in metallurgy and the refractory industry. __________ Translated from Novye Ogneupory, No. 9, pp. 32–35, September 2007.     

Measurement of blood acetoacetate and beta-hydroxybutyrate in an automatic analyser

g-hydroxybutyrate and acetoacetate as well as lactate and pyruvate are intermediary metabolites normally present in blood. The g-hydroxybutyrate/acetoacetate ratio is an expression of the mitochondrial oxido-reduction state. This ketone body ratio can provide a clue to diagnosis and metabolic status in congenital errors of the electron transport chain and pyruvate metabolism. The standardization of these analytical procedures improves the interpretation of the results helping in the difficult diagnosis of mitochondrial diseases in children. This study describes an adaptation to a Dimension R 2 L (Dade Behring, Newark, Delaware, USA) automatic analyser for a method to measure blood ketone bodies (g-hydroxybutyrate and acetoacetate). The method allows the metabolites to be measured directly in nondeproteinized plasma (fluoride/ethylenediaminetetraacetic acid). This adaptation simplifies the analytical procedure and limits the turnaround time to 20 minutes. With a sample volume of 200 mu l metabolite concentrations ranging from 12 to 1300 mu molL(-1) of g-hydroxybutyrate and from 10 to 450 mu molL(-1) of acetoacetate may be measured with a reliable analytical response.     

Automated analyser for monitoring the contents of hydrocarbons in gas emitted from exploratory bore-holes in the gas and oil industry

An automated analyser for total hydrocarbon contents and hydrocarbon composition (from methane to pentanes) was constructed and tested in both laboratory and field exploitation. It used two-channel analysis: continuous measurements of total hydrocarbon contents and periodic (90 or 150 s) composition analysis after separation of hydrocarbons on a gas chromatographic column. Flame ionization detectors were used in both channels. A simple 16-bit analogue-to-digital converter was used (4.8, practically four orders of magnitude), while the full measuring range (six orders of magnitude) was ensured by automatic dilution of the sample (or standard) with clean air. Full control of the operating (calibration/analyses) cycle was performed by microcomputer. An external programme, based on a computer provided with full information on the instrument operating conditions, presents the results of calibrations/analyses and enables them to be archived in a standard database used in the oil/gas drilling industry (N-LAB) by providing a suitable link. The instrument measuring range was 1 ppm to 100% with precision not worse than 5% at the detection limit. The analyser can operate autonomously for two months, recalibrating itself daily.     

Centrifugation and capillarity integrated into a multiple analyte whole blood analyser

A unique clinical chemistry analyser is described which processes 90 μl of whole blood (fingerstick or venous) into multiple aliquots of diluted plasma and reports the results of 12 tests in 14 min. To perform a panel of tests, the operator applies the unmetered sample directly into a single use, 8 cm diameter plastic rotor which contains the required liquid diluent and dry reagents. Using centrifugal and capillary forces, the rotor meters the required amount of blood, separates the red cells, meters the plasma, meters the diluent, mixes the fluids, distributes the fluid to the reaction cuvettes and mixes the reagents and the diluted plasma in the cuvettes. The instrument monitors the reagent reactions simultaneously using nine wavelengths, calculates the results from the absorbance data, and reports the results.     

Evaluation of the Technicon Axon analyser

An evaluation of the Technicon Axon analyser was carried out following the guidelines of the ‘Sociedad Española de Química Clínica’ and the European Committee for Clinical Laboratory Standards.A photometric study revealed acceptable results at both 340 nm and 404 nm. Inaccuracy and imprecision were lower at 404 nm than at 340 nm, although poor dispersion was found at both wavelengths, even at low absorbances. Drift was negligible, the imprecision of the sample pipette delivery system was greater for small sample volumes, the reagent pipette delivery system imprecision was acceptable and the sample diluting system study showed good precision and accuracy.Twelve analytes were studied for evaluation of the analyser under routine working conditions. Satisfactory results were obtained for within-run imprecision, while coefficients of variation for betweenrun imprecision were much greater than expected. Neither specimenrelated nor specimen-independent contamination was found in the carry-over study. For all analytes assayed, when comparing patient sample results with those obtained in a Hitachi 737 analyser, acceptable relative inaccuracy was observed.     

Evaluation of the Dacos 3.0 analyser

The selective multitest Coulter Dacos 3.0 analyser was evaluated according to the guidelines of the Comisión de Instrumentación de la Sociedad Española de Química Clínica and of the European Committee for Clinical Laboratory Standards.The evaluation was performed in four steps: examination of the analytical units; evaluation of routine working; study of interferences; and assessment of practicability.The evaluation included a photometric study. The inaccuracy is acceptable for 340 nm and 420 nm, and the imprecision at absorbances from 0.05 to 2.00 ranged from 0.06 to 0.28% at 340 nm and from 0.06 to 0.08% at 420 nm. The linearity showed some dispersion at low absorbance for PNP at 420 nm and the drift was negligible.The imprecision of the pipette delivery system, the temperature control system and the washing system were satisfactory.In routine work conditions, seven analytical methods were studied: glucose, creatinine, iron, total protein, AST, ALP and calcium. Within-run imprecision ranged, at low concentrations, from 0.9% (CV) for glucose, to 7.6% (CV) for iron; at medium concentrations, from 0.7% (CV) for total protein to 5.2% (CV) to creatinine; and at high concentrations, it ranged from 0.6% (CV) for glucose to 3.9% (CV) for ALP.Between-run imprecision at low concentrations ranged from 1.4% (CV) for glucose to 15.1% (CV) for iron; at medium concentrations it ranged from 1.2% (CV) for protein to 6.7% (CV) for iron; and at high concentrations the range is from l.2for AST to 5.7% (CV) for iron.No contamination was found in the sample carry-over study. Some contamination was found in the reagent carry-over study (total protein due to iron and calcium reagents). Relative inaccuracy is good for all the constituents assayed. Only LDH (high and low levels) and urate (low level) showed weak and negative interference caused by turbidity, and γ-GT (high level) and amylase, bilirubin and ALP (two levels) showed a negative interference caused by haemolysis.     

Evaluation of the Hitachi 717 analyser

The selective multitest Boehringer Mannheim Hitachi 717 analyser was evaluated according to the guidelines of the Comisión de Instrumentación de la Sociedad Española de Química Clinica and the European Committee for Clinical Laboratory Standards. The evaluation was performed in two steps: examination of the analytical units and evaluation in routine operation.The evaluation of the analytical units included a photometric study: the inaccuracy is acceptable for 340 and 405 nm; the imprecision ranges from 0.12 to 0.95% at 340 nm and from 0.30 to 0.73 at 405 nm, the linearity shows some dispersion at low absorbance for NADH at 340 nm, the drift is negligible, the imprecision of the pipette delivery system increases when the sample pipette operates with 3 μl, the reagent pipette imprecision is acceptable and the temperature control system is good.Under routine working conditions, seven determinations were studied: glucose, creatinine, iron, total protein, AST, ALP and calcium. The within-run imprecision (CV) ranged from 0.6% for total protein and AST to 6.9% for iron. The between run imprecision ranged from 2.4% for glucose to 9.7% for iron. Some contamination was found in the carry-over study. The relative inaccuracy is good for all the constituents assayed.     

Correlation of fasting blood glucose and haemoglobin A1c measured with an automated analyser

A subtype of glycohaemoglobin, haemoglobin (Hb) A_1c, in specimens of whole blood was assayed on a new automated analyser that makes use of high-pressure liquid chromatography. The analyser provided precise and reproducible values. The mean of the HbA_1c values was lower than that with an older instrument. The mean tended to increase with the age of the subjects, who were undergoing routine health examinations. No sex difference was found. When measurement was made 1 h after the subjects drank 50g of glucose, the value of HbA_1c was unaffected. Correlation was strong between the HbA_1c value and the fasting blood glucose value, which suggested that fasting blood glucose could be estimated from the HbA_1c value.     

Criteria for the assessment of analyser practicability

This article lists the theoretical criteria that need to be considered to assess the practicability of an automatic analyser. Two essential sets of criteria should be taken into account when selecting an automatic analyser: ‘reliability’ and ‘practicability’. Practibility covers the features that provide information about the suitability of an analyser for specific working conditions.These practibility criteria are classsified in this article and include the environment; work organization; versatility and flexibility; safely controls; staff training; maintenance and operational costs.     

Experience with the lovibond colour vision analyser

A method of detecting and quantifying defective colour vision using the Lovibond Colour Vision Analyzer is described. The results obtained in tests on 120 subjects, including 20 colour defectives, are discussed and compared with results from the Ishihara Test Plates.     

Evaluation of the Olympus AU-510 analyser

The selective multitest Olympus AU-510 analyser was evaluated according to the recommendations of the Comision de Instrumentacion de la Sociedad Española de Quimica Clinica and the European Committee for Clinical Laboratory Standards. The evaluation was carried out in two stages: an examination of the analytical units and then an evaluation in routine work conditions. The operational characteristics of the system were also studied.The first stage included a photometric study: dependent on the absorbance, the inaccuracy varies between +0.5% to -0.6% at 405 nm and from -5.6% to 10.6% at 340 nm; the imprecision ranges between -0.22% and 0.56% at 405 nm and between 0.09% and 2.74% at 340 nm. Linearity was acceptable, apart from a very low absorbance for NADH at 340 nm; and the imprecision of the serum sample pipetter was satisfactory.Twelve serum analytes were studied under routine conditions: glucose, urea urate, cholesterol, triglycerides, total bilirubin, creatinine, phosphate, iron, aspartate aminotransferase, alanine aminotransferase and gamma-glutamyl transferase.The within-run imprecision (CV%) ranged from 0.67% for phosphate to 2.89% for iron and the between-run imprecision from 0.97% for total bilirubin to 7.06% for iron. There was no carryover in a study of the serum sample pipetter. Carry-over studies with the reagent and sample pipetters shows some cross contamination in the iron assay.