Determination of Total Selenium in Infant Formulas: Comparison of the Performance of FIA and MCFA Flow Systems

Two flow methods, based, respectively, on flow-injection analysis (FIA) and on multicommutated flow analysis (MCFA), were compared with regard to their use for the determination of total selenium in infant formulas by hydride-generation atomic absorption spectrometry. The method based on multicommutation provided lower detection and quantification limits (0.08 and 0.27 μg L−1 compared to 0.59 and 1.95 μ L−1, resp.), higher sampling frequency (160 versus. 70 samples per hour), and reduced reagent consumption. Linearity, precision, and accuracy were similar for the two methods compared. It was concluded that, while both methods proved to be appropriate for the purpose, the MCFA-based method exhibited a better performance

Development of a Low-Cost SIA-Based Analyser for Water Samples

An automated multiparametric water analyser was developed and evaluated. The system was based on Sequential Injection Analysis and featured a photometric detection system comprising a tricolour RGB LED source and a photodiode. A program compiled in Visual Basic was used to control the SIA flow system, the LEDs, and the data acquisition and processing. The program loads and executes methods written in ASCII and stored as text files. The system was capable of handling up to four methods simultaneously. When used to carry out methods based on the APHA standard methods, the figures of merit obtained were considered satisfactory for the purpose. The total cost was under US $4600. It was concluded that the analyser is appropriate for routine use and has potential for an increased number of simultaneous methods and for enhanced capabilities if new versions of the software are developed

Multiparametric Flow System for the Automated Determination of Sodium, Potassium, Calcium, and Magnesium in Large-Volume Parenteral Solutions and Concentrated Hemodialysis Solutions

A multiparametric flow system based on multicommutation and binary sampling has been designed for the automated determination of sodium, potassium, calcium, and magnesium in large-volume parenteral solutions and hemodialysis concentrated solutions. The goal was to obtain a computer-controlled system capable of determining the four metals without extensive modifications. The system involved the use of five solenoid valves under software control, allowing the establishment of the appropriate flow conditions for each analyte, that is, sample size, dilution, reagent addition, and so forth. Detection was carried out by either flame atomic emission spectrometry (sodium, potassium) or flame atomic absorption spectrometry (calcium, magnesium). The influence of several operating parameters was studied. Validation was carried out by analyzing artificial samples. Figures of merit obtained include linearity, accuracy, precision, and sampling frequency. Linearity was satisfactory: sodium, r 2 >0.999 ( 0.5 – 3.5 g/L), potassium, r 2 >0.996 (50–150 mg/L), calcium, r 2 >0.999 (30–120 mg/L), and magnesium, r 2 >0.999 (20–40 mg/L). Precision ( s r , %, n=5 ) was better than 2.1 %, and accuracy (evaluated through recovery assays) was in the range of 99.8 %– 101.0 % (sodium), 100.8 – 102.5 % (potassium), 97.3 %– 101.3 % (calcium), and 97.1 %– 99.8 % (magnesium). Sampling frequencies ( h −1 ) were 70 (sodium), 75 (potassium), 70 (calcium), and 58 (magnesium). According to the results obtained, the use of an automated multiparametric system based on multicommutation offers several advantages for the quality control of large-volume parenteral solutions and hemodialysis concentrated solutions

A Simple Automated Method for the Determination of Nitrate and Nitrite in Infant Formula and Milk Powder Using Sequential Injection Analysis

A fast and efficient automated method using a sequential injection analysis (SIA) system, based on the Griess, reaction was developed for the determination of nitrate and nitrite in infant formulas and milk powder. The system enables to mix a measured amount of sample (previously constituted in the liquid form and deproteinized) with the chromogenic reagent to produce a colored substance whose absorbance was recorded. For nitrate determination, an on-line prereduction step was added by passing the sample through a Cd minicolumn. The system was controlled from a PC by means of a user-friendly program. Figures of merit include linearity (r2 > 0.999 for both analytes), limits of detection (0.32 mg kg−1 NO3-N, and 0.05 mg kg−1 NO2-N), and precision (sr%) 0.8–3.0. Results were statistically in good agreement with those obtained with the reference ISO-IDF method. The sampling frequency was 30 hour−1 (nitrate) and 80 hour−1 (nitrite) when performed separately

Diseño, construcción y evaluación de un analizador autónomo in situ para la monitorización de los niveles de fósforo y nitrógeno en aguas superficiales. Primeros resultados.

Se describe un prototipo de analizador automatizado de bajo costo capaz de operar in situ junto a un cuerpo de agua realizando la determinación analítica de los niveles de fósforo (ortofosfato) y nitrógeno (nitrato+nitrito), así como pH y temperatura, transmitiendo los resultados obtenidos a una estación remota mediante internet inalámbrica. Las determinaciones de fósforo y nitrógeno son realizadas mediante métodos de desarrollo de color con detección fotométrica implementados en un sistema de flujo pulsado. Para el control y adquisición de datos se recurrió a la plataforma de microcontroladores Arduino. El sistema opera con baterías recargables y habilita el uso de un panel solar para su recarga. La evaluación preliminar de los métodos analíticos realizada en el laboratorio arrojó cifras de mérito perfectamente adecuadas para los fines buscados. Está prevista una evaluación de campo donde se estudiará el desempeño del equipo en condiciones reales. Se entiende que el uso de este tipo de sistemas que no requieren personal para su operación puede resultar de utilidad en el análisis ambiental.A prototype of a low-cost automated analyser capable of in situ operation next to a water body is described. The analyser can determine levels of phosphorus (orthophosphate) and nitrogen (nitrate+nitrite), along with pH and temperature, transmitting the results to a remote station via wireless internet. Phosphorus and nitrogen determinations are carried out by means of photometric methods, implemented in a pulsed-flow system. For control and data acquisition the open-source Arduino platform of microcontrollers was used. The system runs on rechargeable batteries, with the possible support of a solar panel. Preliminary evaluation of the analytical methods carried out in the laboratory showed figures of merit fit for the purpose. A field evaluation is foreseen in the near future, where the analyser will be tested under real conditions. This type of instruments is considered to be potentially useful in environmental analysis

Diseño, construcción y evaluación de un analizador autónomo in situ para la monitorización de los niveles de fósforo y nitrógeno en aguas superficiales. Primeros resultados = Design, construction and evaluation of an in situ autonomous analyser for monitoring of phosphorus and nitrogen levels in surface waters. First results

Se describe un prototipo de analizador automatizado de bajo costo capaz de operar in situ junto a un cuerpo de agua realizando la determinación analítica de los niveles de fósforo (ortofosfato) y nitrógeno (nitrato+nitrito), así como pH y temperatura, transmitiendo los resultados obtenidos a una estación remota mediante internet inalámbrica. Las determinaciones de fósforo y nitrógeno son realizadas mediante métodos de desarrollo de color con detección fotométrica implementados en un sistema de flujo pulsado. Para el control y adquisición de datos se recurrió a la plataforma de microcontroladores Arduino. El sistema opera con baterías recargables y habilita el uso de un panel solar para su recarga. La evaluación preliminar de los métodos analíticos realizada en el laboratorio arrojó cifras de mérito perfectamente adecuadas para los fines buscados. Está prevista una evaluación de campo donde se estudiará el desempeño del equipo en condiciones reales. Se entiende que el uso de este tipo de sistemas que no requieren personal para su operación puede resultar de utilidad en el análisis ambiental

Einfluss der Fussbodendesinfektion auf die mikrobielle und partikuläre Belastung der Raumluft im Operationsfeld-relevanten LAF-Strömungsmuster

Ziel der Studie war die Beurteilung der Notwendigkeit einer routinemäßigen desinfizierenden Fußbodenreinigung im Greifswalder Zentral-OP (Neubau) mit besonderer Berücksichtigung der Raumlufttechnischen Anlage (RLT-A). Dazu wurden über einen Zeitraum von 4 Wochen die 2 OP-Säle der Augenchirurgie jeweils abwechselnd im Wochentakt einer Wischdesinfektion nach jeder OP bzw. nur bei sichtbaren Verschmutzungen unterzogen. Für den Vergleich der Luftqualität wurden Partikel- und Koloniezahlen der Raumluft inner- und außerhalb des Laminar Air Flow (LAF) sowie die Erregerbelastung im OP-Gebiet (Instrumententray und OP-Tisch) erfasst. Außerdem erfolgte die Überprüfung evtl. aufgetretener postoperativer Wundinfektionen innerhalb eines Jahres. Sowohl Partikel- als auch Luftkoloniezahlen wiesen keine signifikanten Unterschiede bei Betrachtung des Wischvorgangs auf. Wurde die Anästhesieart berücksichtigt, fielen signifikant erhöhte Partikelwerte (< 5 µm) unter Intubationsnarkose (ITN) auf. Des Weiteren konnte eine Korrelation zwischen den Koloniezahlen auf dem Instrumententray und der OP-Dauer bei Wischen nach jeder OP festgestellt werden. Die einmal wöchentlich erhobene Fußbodenkontamination brachte keine signifikanten Unterschiede bezüglich des Einflusses der Wischdesinfektion. Es traten, soweit beurteilbar, innerhalb eines Jahres keine postoperativen Wundinfektionen auf. Daraus lässt sich schlussfolgern, dass eine desinfizierende Fußbodenreinigung unter dem Einfluss des LAF nicht notwendig ist, sondern eine gezielte Desinfektion bei sichtbaren Verschmutzungen bzw. Kontamination mit Blut oder anderem erregerhaltigem Material ausreicht. Aus wirtschaftlicher und organisatorischer Sicht ist das vorteilhaft. Die OP-Dauer sollte grundsätzlich so gering wie möglich gehalten werden, da eine Korrelation zur Instrumentenkontamination nachgewiesen wurde.This study’s objective is making a decision if a frequent cleaning disinfection of floors in the central operating theatre in Greifswald is necessary or not, all in special consideration of the air conditioning plant (RLT-A). Over a period of four weeks, one of the two existing operating rooms was disinfected after every use and the other only in the case of visible contamination. This scheme was inverted every week. To compare the air quality, the particle count and total bacteria count were measured inside and outside the laminar air flow. Additionally, the bacteria count was measured in the operating field, consisting of the operating table and the instrument tray. The patients were checked for infected wounds for a duration of one year after the operation. In regard to the way the floors were wiped, no apparent difference in particle or bacteria counts were observed. However, if the results are classified by the method of anesthesia, significantly higher particle counts occour in the < 5 µm, when general anaesthesia was used. Another correlation between bacteria count at the intruments tray and the duration of the operation could be observerd, if the floor was desinfected after every use. Once a week, the contamination of the floor was measured, which didn’t show any significant differences regarding the frequency of wiping the floors. Also, no wound infections were observed over the course of one year after the operation. It turns out that a frequent cleaning disinfection isn’t necessary if a LAF is established. In this circumstance, a targeted disinfection of soiled surfaces or areas, contamined with blood or other contagious meterial is sufficient. From an economical and oganizational point of view, this is beneficial. Over all, operations should be kept as short as possible, for a correlation to contamination of the set of instruments could be found and may lead to post operative infections in other circumstances

Desarrollo de un sistema en flujo mediante inyección secuencial (SIA) para la determinación de zinc en leche en polvo y fórmulas infantiles

The development and optimization of a sequential injection analysis (SIA) flow system is presented for the determination of zinc in milk powder and infant formulae. The determination is based on the reaction of Zn(II) with zincon at pH 9 in the presence of sodium citrate to mask the interfering matrix with spectrophotometric detection at 612 nm. The system was optimized by multivariate experiments. The validated system presented a linear range from 0.4 to 10 mg L-1 and the precision of the method was better than 5% (sr(%), n = 10). The detection limit was 0.13 mg L-1. The results obtained using the proposed and reference methods were found to be statistically equivalent. The sampling frequency was 75 samples per hour and the sample and reagent consumption of 0.24 mL per determination. The proposed method was accurate, simple, fast and according to the principles of green chemistry generating just 0.24 mL of chemical waste.Se presenta el desarrollo y optimización de un sistema en flujo con inyección secuencial (SIA) para la determinación de zinc en leche en polvo y fórmulas infantiles. La determinación se basa en la reacción de Zn(II) con zincón a pH 9 en presencia de citrato de sodio para enmascarar interferentes de la matriz con detección espectrofotométrica a 612 nm. El sistema fue optimizado mediante experimentos multivariantes. El sistema validado presentó un rango lineal de 0.4 a 10 mg L-1, la precisión del método fue mejor que 5% (sr,%; n=10). El límite de detección fue 0.13 mg L-1. Los resultados obtenidos utilizando el método propuesto y el de referencia fueron estadísticamente equivalentes. La frecuencia de muestreo fue de 75 muestras/hora y el consumo de muestra y reactivo 0.24 mL por determinación. El método propuesto resultó veraz, simple, rápido y está de acuerdo a los principios de la química verde, generando apenas 0.24 mL de residuos químicos

Determinación de glucosa en miel mediante sistemas en flujo de inyección secuencial (SIA) y multiconmutado (MCFIA): estudio comparativo

Two different flow analysis systems are presented for the automated determination of glucose in honey samples. These are based respectively in Multicommutated Flow Analysis (MCFIA) and Sequential Injection Analysis (SIA) and employ an enzyme reagent in solution and colorimetric detection (Trinder�s method). During validation, both methods presented satisfactory linearity up to 0.8 g L-1 glucose and precision better than 3%, with no significant fructose interference. Validity assessment was performed by the analysis of commercial samples and its comparison to AOAC 954.11 reference method. The differences between the results obtained by each proposed method and the reference method were generally lower than 10%, which was considered acceptable for the desired application. The sampling frequency was 46 samples per hour, higher than the reference methods� one.Se presentan dos diferentes sistemas de análisis en flujo para la determinación automatizada de glucosa en muestras de miel. Los mismos se basan respectivamente en Análisis en Flujo Multiconmutado (MCFIA) y en Análisis por Inyección Secuencial (SIA) y emplean un reactivo enzimático en solución con detección colorimétrica (método de Trinder). Durante la validación, ambos métodos exhibieron linealidad satisfactoria hasta 0.8 g L-1 de glucosa y precisión mejor al 3%, sin interferencia significativa de la fructosa. El estudio de la veracidad se realizó por análisis de muestras comerciales y comparación con el método de referencia AOAC 954.11. Las diferencias entre los resultados arrojados por los métodos propuestos y el método de referencia fueron en general, menores al 10% lo que se consideró aceptable para la aplicación buscada. La frecuencia de muestreo fue de 46 muestras por hora, muy superior a la de los métodos de referencia

Application of statistical techniques to the evaluation of accurancy in the development of pharmaceutical analytical methods

Se presenta una forma sencilla y rigurosa para la verificación de la exactitud durante la validación de metodologías analíticas. Los cálculos requeridos pueden ser fácilmente implementados en planillas electrónicas, muy comunes actualmente en todos los laboratorios.An easy and rigorous procedure is proposed for the verification of accuracy in the validation of anaiytical methodologies. The calculations required may be easily programmed on an electronic worksheet, nowadays easily found in every laboratory.Colegio de Farmacéuticos de la Provincia de Buenos Aire