Automation in Food and Agricultural Laboratories

“ALA members share more similarities than differences, and can learn a great deal from each other.”

Developments in analytical technology are making today's food and agricultural laboratories the center of exciting new achievements and promising new challenges. The catalyst for much of this change is the continued advancement of laboratory automation, which initially focused on flow injection (FI)-based assays and eventually migrated to laboratory robotics. To quote Sean Connery from the movie The Hunt for Red October, “those were heady times.”

With respect to the food industry, laboratory automation has evolved from moving samples through robotics to miniaturization, where the automation is internal. This issue of JALA provides a snapshot of laboratory automation in the food and agricultural segments in 2009. We are delighted to be able to include articles that show automation in use from the farm to the fork. DNA fingerprinting of grain seeds showcases the importance of ingredient quality. Manufacturing efficiencies ethanol production and the cheese industry are highlighted. Continued advancements in microbiological testing are key components to the safety of the entire food supply. All of these contributions provide important perspectives on how innovative automation solutions are driving progress in this unique segment of the ALA membership. These contributions also illustrate how automation technologies and procedures harnessed by a particular industry (such as food and agriculture) can be familiar to laboratories that serve other industries (such as drug discovery and development, forensic and security science, or energy and petrochemicals). Ours is a unique scientific-specific specialty, and clearly, ALA members share more similarities than differences, and can learn a great deal from each other.

I sincerely thank the authors for taking time from their busy schedules to prepare the interesting articles showcased in this special issue. Thanks also to C.J. Flint, Stephen Hughes, and my friends and colleagues on the JALA Editorial Board. Special thanks to Nan Hallock and Doug Gurevich for their good humor and assistance. Finally, I'd like to send thanks to The Hershey Company for its continued commitment to excellence from one of us (me!) who was the proud owner of Candice, the eleventh robot Zymark produced.

With a nod to Hilmar Weinmann and Kerstin Thurow's regular “Literature Highlights” column, what follows are some selected articles from recent literature that relate to applications of laboratory automation in food analysis. I have purposely used the adjective “selected,” because anyone who attempts to conduct a broad overview of this topic using Google, Google Scholar, Scopus, or any of the other commercial databases will end up with a laundry list of articles on a plethora of topics. Therefore, I chose some examples that are topical (such as the antioxidant citation) or intriguing (such as the applications of electronic noses). I hope you find this information informative and useful.

Sincerely,

W. Jeffrey Hurst, Ph.D.

Flow Injection-Based Methods for Fast Screening of Antioxidant Capacity

(Magalhães, Santos, Segundo, Reis, Lima—REQUIMTE, Serviço de Química-Física, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, 4099–030 Porto, Portugal)

The role and importance of antioxidants in different fields, ranging from physiology to food technology, have become evident in the past years, requiring adequate analytical methodologies. Therefore, the determination of antioxidant capacity as a routine or screening analysis fosters its automation. In this context, several FI methods based on scavenging of 2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical cation (ABTS(+)) or 2,2-diphenyl-1-picrylhydrazyl radical (DDPH) or based on the determination of total reducing capacity have been proposed. The objective of this review is to critically compare the different approaches, regarding their degree of automation, their performance versus the respective batch procedure and its applicability to real samples (Talanta 2009, 77(5), 1559–1566).

Determination of Macrolide Antibiotics in Meat and Fish Using Pressurized Liquid Extraction and Liquid Chromatography-Mass Spectrometry

(Berrada, Borrull, Font, Marcé—Laboratory of Food Chemistry and Toxicology, Faculty of Pharmacy, Universitat de València, Avda Vicent Andres Estellés s/n, 46100 València, Burjassot, Spain. [e-mail])

We developed a method for determining the quantities of seven macrolide antibiotics in meat and fish by using pressurized liquid extraction (PLE) and liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The PLE was optimized with regard to solvents, temperature, pressure, extraction time, and number of cycles. The optimum conditions were methanol as the extraction solvent, a temperature of 80 °C, a pressure of 1500 ψ, an extraction time of 15 min, two cycles, a flush volume of 150%, and a purge time of 300 s. All recoveries for macrolide antibiotics were over 77% at 200 μg/kg, except for erythromycin, which was 58%. The repeatability and reproducibility on days in between, expressed as the relative standard deviation (%RSD) (n = 12), were lower than 10% and 12%, respectively. The quantification limits of all compounds were 25 μg/kg of dry weight of animal muscle except for troleandomycin (50 μg/kg). The method was applied to determine the pharmaceuticals in real samples taken from 18 meat and fish samples. The results showed that PLE is a quantitative short time-consuming technique, with use of smaller initial sample sizes. Greater specificity and selectivity in extraction and increased potential for automation were shown (J. Chromatogr. A 2008, 1208(1–2), 83–89 [Epub 2008 Sep 4]).

Recent Developments in Solid-Phase Microextraction

(Risticevic, Niri, Vuckovic, Pawliszyn—Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada)

The main objective of this review is to describe the recent developments in solid-phase microextraction (SPME) technology in food, environmental, and bioanalytical chemistry applications. We briefly introduce the historical perspective on the very early work associated with the development of theoretical principles of SPME, but particular emphasis is placed on the more recent developments in the area of automation, HT analysis, SPME method optimization approaches, and construction of new SPME devices and their applications. The area of SPME automation for both GC and LC applications is particularly addressed in this review, as the most recent developments in this field have allowed the use of this technology for HT applications. The development of new autosamplers with SPME compatibility and new-generation metal fiber assemblies has enhanced sample throughput for SPME-GC applications, the latter being attributed to the possibility of using the same fiber for several hundred extraction/injection cycles. For LC applications, HT analysis (>1000 samples per day) can be achieved for the first time with a multi-SPME autosampler that uses multi-well plate technology and allows SPME sample preparation of up to 96 samples in parallel. The development and evolution of new SPME devices, such as needle trap, thin-film microextraction, and cold-fiber headspace SPME have offered significant improvements in performance characteristics compared with the conventional fiber-SPME arrangement (Anal. Bioanal. Chem. 2008, 617, 72–84).

Determination of Preservatives in Meat Products by Flow Injection Analysis (Fia)

(Ruiz-Capillas, Jimenez-Colmenero—Department of Meat and Fish Science and Technology, Instituto del Frío (CSIC), Ciudad Universitaria, 28040 Madrid, Spain. [e-mail])

Various preservatives are added to meat products to extend shelf-life and enhance food safety; thus, their determination is essential for legislative purposes and consumer health. Analytical methodologies based on FI analysis (FIA) offer attractive advantages compared with other procedures, such as versatility, precision, low cost, as well as speed and ease of automation. This review considers the status of published FIA methodologies for the determination of preservatives in meat products. The techniques are described regarding their application to different preservatives (nitrates and nitrites, sulfites, sorbates, benzoates, and p-hydroxybenzoate esters), with emphasis on extraction, separation, detection, and quantification procedures in meat matrices (Food Addit. Contam. Part A Chem. Anal. Control Expo. Risk. Assess. 2008, 25(10), 1167–1178).

Supercritical Fluid Extraction as An On-Line Clean-Up Technique for Rapid Amperometric Screening and Alternative Liquid Chromatography for Confirmation of Paraquat and Diquat in Olive Oil Samples

(Zougagh, Bouabdallah, Salghi, Hormatallah, Rios—Department of Analytical Chemistry and Food Technology, Faculty of Chemistry, University of Castilla-La Mancha, Av. Camilo José Cela s/n, Ciudad Real, Spain)

A rapid and simple method for the direct screening of paraquat (PQ) and diquat (DQ) in olive oil samples is proposed. The sample screening method involves supercritical fluid extraction (SFE) (clean-up followed by the extraction of the analytes) followed by continuous flow electrochemical detection. Those samples for which the total concentration is close to or above the threshold limit established by the Columbian Society for Social Protection (0.05 μg/g^-1) are subsequently analyzed by LC with diode array detection (DAD). This confirmation method allows the determination of PQ and DQ in the range between 0.04 and 1.0 μg/g^-1, with average RSDs lower than 3.5%, and 0.003 and 0.002 μg/g^-1 detection limits for PQ and DQ, respectively. The proposed arrangement opens up interesting prospects for the direct determination of polar pesticides in complex samples with a good throughput and a high level of automation (J. Chromatogr. A 2008, 1204(1), 56–61).

Supercritical Fluid Extraction as an On-Line Clean-Up Technique for Determination of Riboflavin Vitamins in Food Samples by Capillary Electrophoresis with Fluorimetric Detection

(Zougagh, Rios—Department of Analytical Chemistry and Food Technology, University of Castilla-La Mancha, Ciudad Real, Spain)

An automatic method for the separation and determination of riboflavin (RF) vitamins (RF, flavin mononucleotide, and flavin adenine dinucleotide) in food samples (chicken liver, tablet, and powder milk) is proposed. The method is based on the on-line coupling of a supercritical fluid extractor (SFE) with a continuous flow (CF)—capillary electrophoresis (CE) system with guided optical fiber fluorimetric detection (CF—CE—FD). The whole SFE—CF—CE—FD arrangement allowed the automatic treatment of food samples (clean-up of the sample followed by the extraction of the analytes), and the direct introduction of a small volume of the extracted plug to the CE—FD system for the determination of RF vitamins. Fluorescence detection introduced an appropriated sensitivity and contributed to avoid interferences of nonfluorescent polar compounds coming from the matrix samples in the extracted plug. Electrophoretic responses were linear within the 0.05–1 μg/g range, whereas the detection limits of RF vitamins were in the 0.036–0.042 μg/g range. The proposed arrangement opens up interesting prospects for the direct determination of polar analytes in complex samples with a good throughput and high level of automation (Electrophoresis 2008, 29(15), 3213–3219).

A Multiplex Rti-Pcr Reaction for Simultaneous Detection of Escherichia Coli O157:H7, Salmonella Spp. and Staphylococcus Aureus on Fresh, Minimally Processed Vegetables

(Food Microbiology 2008, 25(5), 705–713)

(Elizaquível, Aznar—Departamento de Microbiologíay Ecologia, Universitat de València, Burjassot E-46100, Valencia, Spain)

In this work, a new multiplex single-tube real-time PCR approach is presented for the detection of Escherichia coli O157:H7, Salmonella spp., and Staphylococcus aureus, three of the more frequent food-borne bacterial pathogens that are usually investigated in a variety of food matrices. The study includes the design and specificity testing, of a new primer and probe specific for Salmonella spp. Reaction conditions were adjusted for the simultaneous amplification and detection of specific fragments in the β-glucuronidase (uidA, E. coli) and Thermonulease (nuc, S. aureus) genes, and in the replication origin sequence (oriC, Salmonella spp.). Melting-curve analysis using an SYBR Green I RTi-PCR (Promega, Madison, WI) approach showed characteristic T(m) values demonstrating the specific and efficient amplification of the three fragments. Subsequently, a TaqMan RTi-PCR (Promega, Madison, WI) approach was settled, using FAM, NED, and VIC fluorescently labeled specific probes for an automated detection. It was equally sensitive than uniplex RTi-PCR reactions in S. aureus and E. coli O157:H7, using same amounts of purified DNA, and allowed detection of 10 genome equivalents in the presence of 10(2) or 10(4) genome equivalents of the other two pathogens. Finally, it was tested in artificially inoculated fresh, minimally processed vegetables, revealing a sensitivity of 10 CFU g^-1 each of these pathogens in direct detection, after DNA extraction with DNeasy Tissue Kit (Qiagen). The multiplex RTi-PCR developed scored the sensitivity recognized for PCR in food and it allows a HT and automation, thus it is promising as a rapid and cost-effective test for the food industry.

Automated Analytical Microarrays: A Critical Review

(Seidel, Niessner—Chair for Analytical Chemistry and Institute of Hydrochemistry, Technische Universität München, Marchioninistrasse 17, 81377, München, Germany. [e-mail])

Microarrays provide a powerful analytical tool for the simultaneous detection of multiple analytes in a single experiment. The specific affinity reaction of nucleic acids (hybridization) and antibodies toward antigens is the most common bio analytical method for generating multiplexed quantitative results. Nucleic acid-based analysis is restricted to the detection of cells and viruses. Antibodies are more universal biomolecular receptors that selectively bind small molecules, such as pesticides, small toxins, and pharmaceuticals and to biopolymers (e.g., toxins, allergens) and complex biological structures, such as bacterial cells and viruses. By producing an appropriate antibody, the corresponding antigenic analyte can be detected on a multiplexed immunoanalytical microarray. Food and water analysis along with clinical diagnostics constitute potential application fields for multiplexed analysis. Diverse fluorescence, chemiluminescence, electrochemical, and label-free microarray readout systems have been developed in the last decade. Some of them are constructed as flow-through microarrays by combination with a fluidic system. Microarrays have the potential to become widely accepted as a system for analytical applications, provided that robust and validated results on fully automated platforms are successfully generated. This review gives an overview of the current research on microarrays with the focus on automated systems and quantitative multiplexed applications (Anal. Bioanal. Chem. 2008, 391(5), 1521–1544).

On-Line Monitoring of Acrylamide Formation

(Cook, Channell, Taylor—Samworth Flavour Laboratory, Division of Food Sciences, The University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK. [e-mail])

A system to monitor the formation of acrylamide in model systems and from real food products under controlled conditions of temperature, time, and moisture content has been developed. By humidifying the gas that flows through the sample, some control over moisture content can be affected. Results are presented to show the validity and reproducibility of the technique and its ability to deliver quantitative data. The effects of different processing conditions on acrylamide formation and on the development of color, due to the Maillard reaction, are evaluated (Adv. Exp. Med. Biol. 2005, 561, 303–316).

Fast Microwave-Assisted Free Sugars Washing and Hydrolysis Pre-Treatment for the Flow Injection Determination of Starch in Food

(Caballo-López, Luque de Castro—Department of Analytical Chemistry, Annex C-3, Campus of Rabanales, University of Córdoba, E-14071 Córdoba, Spain)

The approach used consists of a FI manifold assisted by a focused microwave digestor for both fast washing of free sugars and acceleration of the hydrolysis step before the determination of starch in food. The action of microwaves reduces the time for removal of free sugars to a 5-min single washing cycle with ethanol/water and that of the subsequent starch hydrolysis to a 10-min step. The sugars formed in the starch hydrolysis are in-line derivatized and photometrically monitored at λ = 460 nm. In this way, automation of pretreatment and determination is achieved with the minimum of both cost and time. The precision of the overall method, expressed as RSD, is 3.75% and the total analysis time is 38 min. Comparison of the results, obtained in applying the method to flour and bread, is in agreement with those provided by the manual methods (Talanta Mar 2003, 59(4), 837–843).

Where are We in Genomics?

(Hocquette—INRA, Herbivore Research Unit, Muscle Growth and Metabolism Group, Theix, 63122 Saint-Geněs Champanelle, France. [e-mail])

Genomic studies provide scientists with methods to quickly analyze genes and their products en masse. The first HT techniques to be developed were sequencing methods. A great number of genomes from different organisms have thus been sequenced. Genomics is now shifting to the study of gene expression and function. In the past 5–10 years genomics, proteomics, and HT microarray technologies have fundamentally changed our ability to study the molecular basis of cells and tissues in health and diseases, giving a new comprehensive view. For example, in cancer research we have seen new diagnostic opportunities for tumor classification, and prognostication. A new exciting development is metabolomics and laboratory-on-a-chip techniques (which combine miniaturization and automation) for metabolic studies. However, to interpret the large amount of data, extensive computational development is required. In the coming years, we will see the study of biological networks dominating the scene in physiology. The great accumulation of genomics information will be used in computer programs to simulate biologic processes. Originally developed for genome analysis, bioinformatics now encompasses a wide range of fields in biology from gene studies to integrated biology (i.e., combination of different data sets from genes to metabolites). This is systems biology that aims to study biological organisms as a whole. In medicine, scientific results and applied biotechnologies arising from genomics will be used for effective prediction of diseases and risk associated with drugs. Preventive medicine and medical therapy will be personalized. Widespread applications of genomics for personalized medicine will require associations of gene expression pattern with diagnoses, treatment, and clinical data. This will help in the discovery and development of drugs. In agriculture and animal science, the outcomes of genomics will include improvement in food safety, in crop yield, in traceability, and in quality of animal products (dairy products and meat) through increased efficiency in breeding and better knowledge of animal physiology. Genomics and integrated biology are huge tasks and no single laboratory can pursue this alone. We are probably at the end of the beginning rather than at the beginning of the end because genomics will probably change biology to a greater extent than previously forecasted. In addition, there is a great need for more information and better understanding of genomics before complete public acceptance (J. Physiol. Pharmacol. 2005, 56(Suppl 3), 37–70).

Analytical Approaches to Expanding the Use of Capillary Electrophoresis in Routine Food Analysis

(Castañeda, Rodríguez-Flores, Ríos—Department of Analytical Chemistry and Food Technology, Faculty of Chemistry, University of Castilla—La Mancha, Avda. Camilo José Cela, 10, E-13004 Ciudad Real, Spain)

CE is becoming an ever more powerful analytical technique for the separation, identification, and quantification of a wide variety of compounds of interest in many application fields. Particularly in food analysis this technique can offer interesting advantages over chromatographic techniques because of its greater simplicity and efficiency. Nevertheless, CE needs to advance with regard to compatibility with sample matrices, sensitivity, and robustness of the methodologies to gain even wider acceptance in food analysis laboratories, especially for routine work. This article presents various approaches to expanding the analytical usefulness of CE in food analysis, discussing their advantages over conventional CE. These approaches focus on sample screening, automated sample preparation with on-line CE arrangements, and the automatic integration of calibration in routine analytical work with CE (J. Sep. Sci. 2005, 28(9–10), 915–924).

Chlorophenols Identification in Water Using An Electronic Nose and Anns (Artificial Neural Networks) Classification

(Vásquez, Lorenzo, Cela—Aquagest, Central Laboratory, C/Isidro Parga Pondal no 9 15702 Santiago de Compostela, Spain. [e-mail])

Electronic artificial noses are being developed as systems for the automated detection and classification of odors, vapors, and gases. In the food industry, such devices are used as aids for quality control or process-monitoring tools. An EN is generally composed of a chemical sensing system and a pattern recognition system (e.g., artificial neural network [ANN]). An EN based on a nonspecific conducting polymer array was used to monitor chlorophenols in water samples. Operational parameters for the EN were optimized by a Plackett—Burman factorial design. The experimental parameters studied were sample volume, platen temperature, sample equilibration time, loop fill time, sample pressurization time, and injection time. Optimal experimental conditions were applied to chlorophenol's determination and differentiation in ultrapure water samples spiked with the chlorophenols listed by Environmental Protection Agency. Data analysis was carried out using principal component analysis (PCA) and ANNs to predict the chlorophenols presence in water samples. The obtained results showed that it was possible to differentiate the five chlorophenol groups—monochlorophenol, dichlorophenol, trichlorophenol, tetrachlorophenol, and pentachlorophenol. Differentiation of chlorophenol groups was based on Mahalanobis distance between the formed clusters. This Mahalanobis distance is designated by the Quality Factor, a value <2 for this quality factor means a good differentiation between the clusters (Water Sci. Technol. 2004, 49(9), 99–105).

Dna Microarray Technology in Nutraceutical and Food Safety

(Liu-Stratton, Roy, Sen—Laboratory of Molecular Medicine and DNA Microarray & Genetics Facility, Department of Surgery, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Medical Center, 473 W. 12th Avenue, Columbus, OH 43210, USA)

The quality and quantity of diet is a key determinant of health and disease. Molecular diagnostics may play a key role in food safety related to genetically modified foods, food-borne pathogens, and novel nutraceuticals. Functional outcomes in biology are determined, for the most part, by net balance between sets of genes related to the specific outcome in question. The DNA microarray technology offers a new dimension of strength in molecular diagnostics by permitting the simultaneous analysis of large sets of genes. Automation of assay and novel bioinformatics tools make DNA microarrays a robust technology for diagnostics. Since its development a few years ago, this technology has been used for the applications of toxicogenomics, pharmacogenomics, cell biology, and clinical investigations addressing the prevention and intervention of diseases. Optimization of this technology to specifically address food safety is a vast resource that remains to be mined. Efforts to develop diagnostic custom arrays and simplified bioinformatics tools for field use are warranted (Toxicol. Lett. 2004, 150(1), 29–42).

Detection of Salmonella from Chicken Rinses and Chicken Hot Dogs with the Automated Bax Pcr System

(Bailey, Cosby—U.S. Department of Agriculture, Agricultural Research Service, Russell Research Center, P.O. Box 5677, Athens, Georgia 30604, USA. [e-mail])

The BCL2 associated x protein (BAX) system with automated PCR detection was compared with standard cultural procedures for the detection of naturally occurring and spiked Salmonella in 183 chicken carcass rinses and 90 chicken hot dogs. The automated assay procedure consists of overnight growth (16–18 h) of the sample in buffered peptone broth at 35 °C, transfer of the sample to lysis tubes, incubation and lysis of the cells, transfer of the sample to PCR tubes, and placement of tubes into the cycler—detector, which runs automatically. The automated PCR detection assay takes about 4 h after 16–24 h of overnight preenrichment. The culture procedure consists of preenrichment, enrichment, plating, and serological confirmation and takes about 72 h. Three trials involving 10–31 samples were carried out for each product. Some samples were spiked with Salmonella typhimurium, Salmonella heidelberg, Salmonella montevideo, and Salmonella enteritidis at 1–250 cells/mL of rinse or 1–250 cells/g of meat. For unspiked chicken rinses, Salmonella was detected in two of 61 samples with the automated system and in one of 61 samples with the culture method. Salmonella was recovered from 111 of 122 spiked samples with the automated PCR system and from 113 of 122 spiked samples with the culture method. For chicken hot dogs, Salmonella was detected in all 60 of the spiked samples with both the automated PCR and the culture procedures. For the 30 unspiked samples, Salmonella was recovered from 19 samples with the automated PCR system and from 10 samples with the culture method. The automated PCR system provided reliable Salmonella screening of chicken product samples within 24 h (J. Food Prot. 2003, 66(11), 2138–2140).

Electronic Nose-Based Tea Quality Standardization

(Dutta, Kashwan, Bhuyan, Hines, Gardner—Department of Engineering, University of Warwick, Coventry CV4 7AL, UK)

In this article we have used a metal oxide sensor (MOS)-based EN to analyze five tea samples with different qualities, namely, drier month, drier month again over-fired, well-fermented normal fired in oven, well-fermented over-fired in oven, and underfermented normal fired in oven. The flavor of tea is determined mainly by its taste and smell, which is generated by hundreds of volatile organic compounds (VOCs) and nonvolatile organic compounds present in tea. These VOCs are present in different ratios and determine the quality of the tea. For example, Camellia s. Assamica (Sri Lanka and Assam Tea) and Assamica sinesis (Darjeeling and Japanese Tea) are two different species of tea giving different flavor notes. Tea flavor is traditionally measured through the use of a combination of conventional analytical instrumentation and human or ganoleptic profiling panels. These methods are expensive in terms of time and labor and also inaccurate because of a lack of either sensitivity or quantitative information. In this article an investigation has been made to determine the flavors of different tea samples using an EN and to explore the possibility of replacing existing analytical and profiling panel methods. The technique uses an array of four MOSs, each of which has an electrical resistance that has partial sensitivity to the headspace of tea. The signals from the sensor array are then conditioned by suitable interface circuitry. The data were processed using PCA, Fuzzy C means algorithm (FCM). We also explored the use of a self-organizing map (SOM) method along with a radial basis function network (RBF) and a probabilistic neural network classifier. Using FCM and SOM feature extraction techniques along with RBF neural network we achieved 100% correct classification for the five different tea samples with different qualities. These results prove that our EN is capable of discriminating between the flavors of teas manufactured under different processing conditions, namely overfermented, overfired, underfermented, and so forth (Neural Netw. 2003, 16(5–6), 847–853).

Determination of Daidzein and Genistein in Soybean Foods by Automated On-Line In-Tube Solid-Phase Microextraction Coupled to High-Performance Liquid Chromatography

(Miani, Narimatsu, Kataoka—Faculty of Pharmaceutical Sciences, Okayama University, Tsushima, Okayama 700–8530, Japan)

An automated on-line method for the determination of the isoflavones, daidzein and genistein, was developed using in-tube SPME coupled to high-performance liquid chromatography (in-tube SPME—HPLC). In-tube SPME is a new extraction technique for organic compounds in aqueous samples, in which analytes are extracted from the sample directly into an open tubular capillary by repeated draw/eject cycles of sample solution. Daidzein, genistein, and their glucosides tested in this study were clearly separated within 8 min by HPLC using an XDB-C8 column (Agilent, Wilmington, DE) with DAD. To optimize the extraction of these compounds, several in-tube SPME parameters were examined. The glucosides daidzein and genistein were analyzed as aglycones after hydrolysis because the glucosides were not concentrated by in-tube SPME. The optimum extraction conditions for daidzein and genistein were obtained with 20 draw/eject cycles of 40 μL of sample using a Supel-Q porous layer open tubular capillary column (Supelco, Bellefonte, PA). The extracted compounds were easily desorbed from the capillary by mobile phase flow, and carryover was not observed. Using the in-tube SPME—HPLC method, the calibration curves of these compounds were linear in the range 5–200 ng/mL, with a correlation coefficient above 0.9999 (n = 18), and the detection limits (S/N = 3) were 0.4–0.5 ng/mL. This method was successfully applied to the analysis of soybean foods without interference peaks. The recoveries of aglycones and glucosides spiked into food samples were above 97% (J. Chromatogr. A 2003, 986(2), 169–177).

Automated Sample Preparationby Pressurized Liquid Extraction-Solid-Phase Extractionfor the Liquid Chromatographic-Mass Spectrometric Investigation of Polyphenols in the Brewing Process

(Papagiannopoulos, Mellenthin—Institute of Food Science and Food Chemistry, University of Bonn, Endenicher Allee 11–13, 53115 Bonn, Germany)

The analysis of polyphenols from solid plant or food samples usually requires laborious sample preparation. The liquid extraction of these compounds from the sample is compromised by apolar matrix interferences, an excess of which has to be eliminated before subsequent purification and separation. Applying PLE to the extraction of polyphenols from hops, the use of different solvents sequentially can partly overcome these problems. Initial extraction with pentane eliminates hydrophobic compounds, such as hop resins and oils and enables the straightforward automated on-line solid-phase extraction as part of an optimized LC-MS analysis (J. Chromatogr. A 2002, 976(1–2), 345–348).

Predictions for Rapid Methods and Automation in Food Microbiology

(Fung—Kansas State University, Department of Animal Science and Industry, Manhattan 66506, USA. [e-mail])

A discussion is presented on the present status of rapid methods and automation in microbiology. Predictions are also presented for development in the following areas: viable cell counts, real-time monitoring of hygiene, PCR, ribotyping, and genetic tests in food laboratories, automated enzyme-linked immunosorbent assay and immunotests, rapid dipstick technology, biosensors for Hazard Analysis Critical Control Point programs, instant detection of target pathogens by computer-generated matrix, effective separation and concentration for rapid identification of target cells, microbiological alert systems in food packages, and rapid alert kits for detecting pathogens at home (J. AO AC Int. 2002, 85(4), 1000–1002).

W. Jeffrey Hurst