High-performance liquid chromatographic determination of cephalosporin antibiotics using 0.3 mm I.D. columns

Validation of analytical methodology for quantification of cefazolin sodium pharmaceutical dosage form by high performance liquid chromatography to be applied for quality control in pharmaceutical industry

A reversed-phase high performance liquid chromatography method was validated for the determination of cefazolin sodium in lyophilized powder for solution for injection to be applied for quality control in pharmaceutical industry. The liquid chromatography method was conducted on a Zorbax Eclipse Plus C18 column (250 x 4.6 mm, 5 μm), maintained at room temperature. The mobile phase consisted of purified water: acetonitrile (60: 40 v/v), adjusted to pH 8 with triethylamine. The flow rate was of 0.5 mL min-1 and effluents were monitored at 270 nm. The retention time for cefazolin sodium was 3.6 min. The method proved to be linear (r2=0.9999) over the concentration range of 30-80 µg mL-1. The selectivity of the method was proven through degradation studies. The method demonstrated satisfactory results for precision, accuracy, limits of detection and quantitation. The robustness of this method was evaluated using the Plackett–Burman fractional factorial experimental design with a matrix of 15 experiments and the statistical treatment proposed by Youden and Steiner. Finally, the proposed method could be also an advantageous option for the analysis of cefazolin sodium, contributing to improve the quality control and to assure the therapeutic efficacy.

New spectrofluorimetric method for determination of cephalosporins in pharmaceutical formulations

A simple, accurate, precise spectrofluorimetric method has been proposed for the determination of three cephalosporins, namely, cefixime (cefi), cephalexine (ceph), and cefotaxime sodium (cefo) in pharmaceutical formulations. This method is based on a reaction between cephalosporins with 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) in alkaline medium, at pH 12.0 for cefi and 13.0 for ceph and cefo to give highly fluorescent derivatives extracted with chloroform and subsequent measurements of the formed fluorescent products at 520, 500 and 510 nm after excitation at 480, 470 and 480 nm for cefi, ceph and cefo respectively. The optimum experimental conditions have been studied. Beer's law is obeyed over concentrations of 10-60 ng/mL, 5-35 ng/mL and 10-60 ng/mL for cefi, ceph and cefo, respectively. The detection limits were 4.20 ng/mL, 2.54 ng/mL and 4.09 ng/mL for cefi, ceph and cefo, respectively, with a linear regression correlation coefficient of 0.99783, 0.99705 and 0.9978 and recoveries in ranges 96.96-105.77, 96.13-102.55 and 95.45-105.39% for cefi, ceph and cefo, respectively. This method is simple and can be applied for the determination of cefi, ceph and cefo in pharmaceutical formulations in quality control laboratories.

Kinetic spectrophotometric determination of certain cephalosporins using oxidized quercetin reagent

A simple, precise and accurate kinetic spectrophotometric method for determination of cefoperazone sodium, cefazolin sodium and ceftriaxone sodium in bulk and in pharmaceutical formulations has been developed. The method is based upon a kinetic investigation of the reaction of the drug with oxidized quercetin reagent at room temperature for a fixed time of 30 min. The decrease in absorbance after the addition of the drug was measured at 510 nm. The absorbance concentration plot was rectilinear over the range 80-400 microg mL(-1) for all studied drugs. The concentration of the studied drugs was calculated using the corresponding calibration equation for the fixed time method. The determination of the studied drugs by initial rate, variable time and rate-constant methods was feasible with the calibration equations obtained but the fixed time method has been found to be more applicable. The analytical performance of the method, in terms of accuracy and precision, was statistically validated; the results were satisfactory. The method has been successfully applied to the determination of the studied drugs in commercial pharmaceutical formulations. Statistical comparison of the results with a well established reported method showed excellent agreement and proved that there is no significant difference in the accuracy and precision.

Analysis of cephalosporin antibiotics

A comprehensive review with 276 references for the analysis of members of an important class of drugs, cephalosporin antibiotics, is presented. The review covers most of the methods described for the analysis of these drugs in pure forms, in different pharmaceutical dosage forms and in biological fluids.

Separation of basic compounds of pharmaceutical interest by using nano-liquid chromatography coupled with mass spectrometry

Nano-liquid chromatography-mass spectrometry (nano-LC-MS) was evaluated for the separation of basic compounds of pharmaceutical interest. The separation of selected beta-blockers, namely nadolol, oxprenolol, alprenolol and propranolol in the presence of terbutaline was performed using two 75 microm I.D. capillaries packed with two different RP18 stationary phases (SP). The best results concerning resolution and efficiency were achieved using the SP where free silanol groups were not present. As expected, this latter SP proved to be very efficient and symmetry factors were observed mainly in the case of the more retained analytes. Baseline resolution of all studied basic compounds was achieved with the Cogent bidentate C18 silica phase (CBC18) eluting analytes at 800 nL/min with a mobile phase containing 500 mM ammonium acetate pH 4.5-water-methanol (1:8:91, v/v/v). The separated basic compounds were revealed using on-column UV detector at 205 nm and electrospray-ion-trap mass spectrometer (ESI-MS). The packed capillary was connected to the MS through a commercial sheath liquid interface or a sheathless nano-spray interface and in both cases the sensitivity was studied and the results compared. Limit of detection (LOD) as low as 0.1 ng/mL was measured for nadolol using the sheathless nano-spray interface and the capillary column packed with the CBC18 stationary phase.

Structural identification and characterization of impurities in ceftizoxime sodium

Ceftizoxime sodium is a parenteral beta-lactamic antibacterial drug. In the synthesis of ceftizoxime sodium, eight process related impurities were detected in HPLC analysis. Pure impurities obtained by both synthesis and preparative HPLC were co-injected with ceftizoxime sample to confirm the retention times in HPLC. The impurities were characterized as, (6R,7R)-7-amino-3-cephem-4-carboxylic acid (impurity I); (6R,7R)-7-[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetamido]-3-cephem-1-oxo-4-carboxylic acid (impurity II); (4RS,6R,7R)-7-[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino) acetamido]-3,4-dihydro-3-cephem-4-carboxylic acid (impurity III); (6R,7R)-7-[(E)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetamido]-3-cephem-4-carboxylic acid (impurity IV); (6R,7R)-7-[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetamido]-3-cephem-N-(3-cephem-4-carboxy-7-yl)-4-carboxamide (impurity V); (6R,7R)-7-[(Z)-2-[[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetylamino]thiazol-4-yl]-2-methoxyiminoacetamido]-3-cephem-4-carboxylic acid (impurity VI); 2-mercaptobenzothiazole (impurity VII) and 2-mercapto benzothiazolyl [(Z)-2-(2-amino-4-thiazolyl)-2-methoxyimino] acetate (impurity VIII). Structural elucidation of all impurities by spectral data ((1)H NMR, (13)C NMR, MS and IR) has been discussed.

Voltammetric behavior and assay of the antibiotic drug cefazolin sodium in bulk form and pharmaceutical formulation at a mercury electrode

The electrochemical behavior of the antibiotic drug cefazolin sodium (CFZ) in Britton-Robinson buffers (pH 2-11) at the mercury electrode was studied by means of dc-polarography, cyclic voltammetry, controlled-potential coulometry and square-wave adsorptive stripping voltammetry techniques. A validated square-wave adsorptive cathodic stripping voltammetric procedure was described for the trace determination of cefazolin in bulk form up to limits of detection and quantitation of 2.6 x 10(-10)M and 8.6 x 10(-10)M, respectively. The method was successfully applied for determination of cefazolin in pharmaceutical preparation without the necessity for samples pretreatment or any time-consuming extraction or evaporation steps prior to the analysis.

The use of a monolithic column to improve the simultaneous determination of four cephalosporin antibiotics in pharmaceuticals and body fluids by HPLC after solid phase extraction—a comparison with a conventional reversed-phase silica-based column

The use of a monolithic column (Chromolith, SpeedROD RP-18e, by Merck) was studied on the determination of cephalosporin antibiotics. Results were compared with those from a previously developed analytical method using conventional silica-based analytical column. A rapid, accurate and sensitive method has been developed and validated for the quantitative simultaneous determination of four cephalosporins: Cephalexine and Cephadroxil (first generation), Cefaclor (second generation) and Cefotaxim (third generation) in pharmaceuticals as well as in human blood serum and urine. Hydroflumethiazide (HFM) (3,4-dihydro-6(trifluoromethyl)-2H-1,2,4-benzothiadiazine-7-sulfonamide-1,1-dioxide) was used as an internal standard at a concentration of 1.5 ng/microL. A rectilinear relationship was observed up to 5 ng/microL for the four compounds. Analysis time was less than 4 min. The statistical evaluation of the method was examined by means of within-day repeatability (n=8) and day-to-day precision (n=8) and was found to be satisfactory with high accuracy and precision results. The method was applied to the determination of the cephalosporins in commercial pharmaceuticals and in biological fluids: human blood serum after solid phase extraction and urine simply after filtration and dilution. Recovery of analytes in spiked serum samples was in the range from 88.7 to 107.8%, while for urine samples recovery was from 98.0 to 105.6%. By comparing the figures of merit for the monolithic column and the silica-based one, regarding the determination of the four cephalosporins investigated in the present study, the outstanding efficiency of the monolithic column can be noticed.

Rapid and sensitive high-performance liquid chromatographic determination of four cephalosporin antibiotics in pharmaceuticals and body fluids

A rapid, accurate and sensitive method has been developed and validated for the quantitative simultaneous determination of four cephalosporins, cephalexin and cefadroxil (first-generation), cefaclor (second-generation) and cefataxim (third-generation), in pharmaceuticals as well as in human blood serum and urine. A Spherisorb ODS-2 250 x 4-mm, 5-microm analytical column was used with an eluting system consisting of a mixture of acetate buffer (pH 4.0)-CH(3)OH 78-22% (v/v) at a flow-rate 1.2 ml/min. Detection was performed with a variable wavelength UV-Vis detector at 265 nm resulting in limit of detection of 0.2 ng for cefadroxil and cephalexin, but only 0.1 ng for cefotaxime and cefaclor per 20-microl injection. Hydrochlorothiazide (HCT) (6-chloro-3,4-dihydro-7 sulfanyl-2H-1,2,4-benzothiadiazine-1-1-dioxide) was used as internal standard at a concentration of 2 ng/microl. A rectilinear relationship was observed up to 8, 5, 12 and 35 ng/microl for cefadroxil, cefotaxime, cefaclor, cephalexin, respectively. Analysis time was less than 7 min. The statistical evaluation of the method was examined by means of within-day repeatability (n=8) and day-to-day precision (n=9) and was found to be satisfactory with high accuracy and precision. The method was applied to the determination of the cephalosporins in commercial pharmaceuticals and in biological fluids: human blood serum after solid-phase extraction and urine simply after filtration and dilution. Recovery of analytes in spiked samples was in the range from 76.3 to 112.0%, over the range of 1-8 ng/microl.

Determination of rotenone in river water utilizing packed capillary column switching liquid chromatography with UV and time-of-flight mass spectrometric detection

Fast and sensitive packed capillary column switching liquid chromatography methodology has been developed for the determination of the pesticide rotenone in river water. Sample volumes of up to 1 ml are loaded onto a 23 x 0.25 mm, 5 microm Kromasil C18 packed capillary precolumn using a noneluting solvent composition of water-acetonitrile (99:1, v/v) at flow-rates up to 100 microl/min prior to solute backflushing onto a 200 x 0.32 mm, 3.5 microm Kromasil C18 packed capillary analytical column using a mobile phase of water-acetonitrile (30:70, v/v) at a flow-rate of 5 microl/min. The method was evaluated using river water samples spiked with rotenone in the concentration range 0.5-50 ng/ml using UV detection. The within-assay precision was between 5.0 and 7.7% relative standard deviation (RSD, n = 6) and the between assay precision was between 7.5 and 8.9% RSD (n = 6). The method was linear within the investigated mass range displaying a calibration curve correlation factor of 0.997. The mass limit of detection was 10 pg corresponding to a concentration limit of detection of 10 pg/ml, using time-of-flight mass spectrometry.

Comparison of several methods used for the determination of cephalosporins. Analysis of cephalexin in pharmaceutical samples

The precision of UV absorbance of intact and acid degraded cephalosporins, ninhydrin, high performance liquid chromatography and iodometric methods used for analysis of cefoxitin, cefotaxime, cephazolin and cephalexin were compared. To obtain the calibration graphs the analytical signal used were: absorbance, first derivative absorbance, second derivative absorbance and H-point Standard Additions Method by using absorbance values at two selected wavelengths as analytical signal. These methods and calibration graphs were also used for the determination of cephalexin in pharmaceutical samples.

Bioequivalence evaluation of two brands of cefaclor 500 mg capsules: quantification of cefaclor using solid phase extraction technique

OBJECTIVE

To assess the bioequivalence of two cefaclor 500 mg capsule formulations, and to develop a new high performance liquid chromatographic (HPLC) method using solid phase extraction technique for the quantification of cefaclor in human plasma.

METHOD

An open, randomized, two-way, crossover trial with a one-week washout period in 25 healthy volunteers. The two commercial brands used were Recocef(Julphar, United Arab Emirates) as test and Ceclor(Eli Lilly, UK) as reference product. The drug was administered with 240 mL of water after a 10-h overnight fast. After dosing, serial blood samples were collected for a period of 8 h. Plasma harvested from blood was analysed for cefaclor by a new HPLC method using a solid phase extraction technique. The limit of detection of cefaclor was 17.6 ng/mL; average recovery was 96.5%; the intraday CV was less than 8% and interday CV was less than 13%. Various pharmacokinetic parameters, including AUC0-t, AUC0-infinity, Cmax, Tmax, T1/2, and Kel, were determined from plasma concentrations for both formulations. Statistical analysis (ANOVA and 90% confidence intervals) were applied to AUC0-t, AUC0-infinity and Cmax for bioequivalence evaluation of two brands. The new HPLC method with solid phase extraction circumvented the problem of mixed polarity of cefaclor and facilitated its extraction from the complex plasma matrix while keeping the background free from interference due to endogenous plasma compounds.

RESULTS

No significant difference was observed between the two brands of cefaclor capsules.

CONCLUSION

Recocef was judged bioequivalent to Ceclor and the two products can therefore be considered to be interchangeable in medical practice.

Determination of cefaclor by selective sample enrichment/clean-up on silica gel bonded polyelectrolyte in ion-exchange column chromatography

A silica gel-bound cationic polyelectrolyte, poly[N-chloranil N,N,N',N'- tetramethylethylene diammonium dichloride], modified as ion-exchanger capable of molecular recognition of beta-lactam antibiotic, was used in solid phase extraction through column chromatography for a sample clean-up and enrichment of analyte from a dilute solution. The optimum and selective sorption conditions for a model antibiotic, cefaclor, were established. The high selectivity of polymer at pH 9.5 and flow rate as high as 5 ml/min were observed for the quantitative sorption of cefaclor. The desorption by 0.1 N HCl at flow rate of 0.1 ml/min and subsequent heating at 80 degrees C for 2 h allowed the antibiotic to be detected as corresponding oxazolone form in UV-spectrophotometric and differential pulse adsorptive stripping voltammetric measurements. The potential of the suggested approach was illustrated by estimating cefaclor in urine and blood plasma samples.

Optimization of separation and migration behavior of cephalosporins in capillary zone electrophoresis

The influences of buffer pH, buffer concentration and buffer electrolyte on the migration behavior and separation of 12 cephalosporin antibiotics in capillary zone electrophoresis using three different types of buffer electrolyte, including phosphate, citrate, and 2-(N-morpholino)ethanesulfonate (MES), were investigated. The results indicate that, although buffer pH is a crucial parameter, buffer concentration also plays an important role in the separation of cephalosporins, particularly when cefuroxime and cefazolin, cephalexin and cefaclor, or cefotaxime and cephapirin are present as analytes at the same time. The electrophoretic mobility of cephalosporins and electroosmotic mobility measured in citrate and MES buffers are remarkably different from those measured in phosphate buffer. With citrate buffer, optimum buffer concentration is confined to a small range (35-40 mM), whereas buffer concentrations up to 300 mM can be used with MES buffer. Complete separations of 12 cephalosporins could be satisfactorily achieved with these three buffers under various optimum conditions. However, the separability of 12 cephalosporins with citrate or MES buffer is better than that with phosphate buffer. As a consequence of a greater electrophoretic mobility of cephalosporins than the electroosmotic mobility with citrate buffer at pH below about 5, some cephalosporins are not detectable. The cloudiness of the peak identification and of the magnitudes of the electrophoretic mobility of cefotaxime and cefuroxime reported previously are clarified. In addition, the pKa values of cephradine, cephalexin, cefaclor, and cephapirin attributed to the deprotonation of either an amino group or a pyridinium group are reported, and the migration behavior of these cephalosporins in the pH range studied is quantitatively described.

Sensitive assay for the determination of cefazolin or ceftriaxone in plasma utilizing LC

A rapid, specific and very sensitive liquid chromatographic assay using standard ultraviolet detection has been developed to measure cefazolin (CFZ) or ceftriaxone (CFX) in small samples (200 microl) of plasma using either drug as the internal standard for measurement of the other. A rapid extraction was performed using C18 bonded Sep Pak cartridges with high extraction efficiency for both drugs. The chromatographic system employed the use of a Nova-Pak C18 4-microm cartridge with a radial compression system preceded by a Guard-Pak with a C18 insert. The mobile phase consisted of an aqueous solution containing 10 mM of dibasic potassium phosphate and 10 mM cetyltrimethylammonium bromide (pH 6.5) with acetonitrile (73:27 v/v). The drug and internal standard (CFZ/CFX) were detected using a UV detector set at a wavelength of 274 nm. Assay results were linearly related to the concentration (r > 0.997) for the wide range which was examined (0.005-120 microg/ml) for either drug. We report the precision, accuracy, recovery, linearity, sensitivity and specificity of this assay. The intra-run and inter-run CV was less than 9.02%. This method is currently being used for clinical therapeutic monitoring and pharmacokinetic studies of CFZ and CFX in patients undergoing cesarean section.

Quantitative determination of some thiazole cephalosporins through complexation with palladium (II) chloride

A simple and sensitive spectrophotometric method has been developed for the determination of five cephalosporins namely cefpodoxime (CFPD), ceftizoxime (CTIZ), ceftazidime (CZD), ceftriaxone (CTRX), and cefixime (CXIM). This method is based on the formation of yellow to yellowish brown complex between palladium (II) chloride and the investigated cephalosporins in the presence of sodium lauryl sulphate (SLS) as surfactant. The reaction conditions were studied and optimized. The procedure was validated. For each drug, the composition of this complex as well as its stability constant were also investigated. The proposed method was used for the determination of the above-mentioned drugs in their commercial preparations. The results were compared statistically with either official or published methods and showed no significant difference between the two methods.

Recent developments in microcolumn liquid chromatography

An overview of the most recent developments in microcolumn liquid chromatography (LC) is presented. A short theoretical discussion on chromatographic dilution and extracolumn bandbroadening is given and also the recent progress and advances in column technology and instrumentation are reviewed. However, the emphasis of this review is on miniaturized sample clean-up, sample introduction techniques and on both established and more recent detection techniques for microcolumn LC. The hyphenation of miniaturized LC columns with other techniques, specifically on multidimensional chromatography and the coupling of microcolumn LC to mass spectrometry is discussed in detail. Both the on-line and automated off-line interfacing to other separation and detection techniques will also be addressed. Finally, a number of typical microcolumn LC applications are presented in order to demonstrate the potential of microcolumn LC methods in a variety of scientific areas.

New spectrophotometric procedure for determining cefotaxime based on derivatization with 1,2-naphthoquinone-4-sulphonate into solid-phase extraction cartridges--application to pharmaceutical and urine samples

Cefotaxime was derivatised with 1,2-naphthoquinone-4-sulphonate (NQS), extracted into solid-phase cartridges (C18) and detected using a UV-visible detection system. Optimum conditions for this new procedure were: hydrogencarbonate-carbonate buffer, pH 10.5, 5-min reaction time at 25 degrees C and an NQS concentration of 7.1x10(-3) mol l(-1). The accuracy and the precision of the liquid-solid procedure were tested. The procedure was used to measure cefotaxime in pharmaceutical and urine samples. The results obtained were contrasted with those reported for a HPLC method for urine samples. The generalized H-point standard additions method was used to measure cefotaxime in urine samples.

Determination of third-generation cephalosporins by high-performance liquid chromatography in connection with pharmacokinetic studies

The third-generation cephalosporins are semisynthetic beta-lactam antibiotics, including several oral and parental agents with extended activity against Gram-negative pathogens. They are generally determined either by microbiological techniques or by high-performance liquid chromatography (HPLC). The major drawback or bioassays is the lack of specificity, especially when a biotransformation of the cephalosporin molecule leads to active metabolites, or when the antibacterial therapy is based on association with drugs. Thus, for many years, numerous reversed-phase HPLC procedures have been proposed to overcome these difficulties. This review presents different HPLC methods proposed for the quantification in biological fluids of fourteen third-generation cephalosporins, ranged between parenteral and oral compounds. The sensitivity and specificity of these chromatographic procedures are discussed with regard to the pharmacokinetic properties of the antibiotics studied.

HPTLC assay of cephalexin and cefaclor in pharmaceuticals

A simple and reliable HPTLC method for the simultaneous determination of cephalexin and cefaclor is developed and validated. The methanol-ethyl acetate-acetone-water (5:2.5:2.5:1.5 v/v/v/v) solvent system is used for the quantitative evaluation of chromatograms. The chromatographic zones, corresponding to the spots of cephalexin and cefaclor on the silica gel plates, are scanned in the reflectance/absorbance mode at 265 nm. The method is found to be reproducible and convenient for the quantitative analysis of cephalexin and cefaclor in its dosage forms.

Capillary high-performance liquid chromatography-fast atom bombardment mass spectrometry of 24 cephem antibiotics

Using capillary high-performance liquid chromatography (HPLC)-fast atom bombardment (FAB) mass spectrometry (MS), both positive and negative FAB mass spectra of 24 cephem antibiotics with diethanolamine (DEA) and glycerol (GLY) as matrices are presented. In the positive mode, an internal quasi-molecular peak together with relatively abundant fragment peaks were obtained from all 24 drugs with both matrices, though DEA provided more information on molecular mass of a compound than did GLY for some drugs. In the negative mode, the background was generally lower than that in the positive, but neither the quasi-molecular nor molecular peak was detected in several drugs with either matrix. The drugs were isolated from serum samples using an octadecyl reversed-phase cartridge; recoveries were generally over 60%, With this isolation and the capillary HPLC-FAB-MS in the positive mode, ceftriaxone and cefazolin, two of the most popular cephem antibiotics, were successfully identified in 0.5 ml of sera obtained from a clinical or an autopsy case.

Chromatographic analysis of antibiotic materials in food

The monitoring of food materials for antibiotic residues is an area of increasing concern and importance due to the potential impact on human health. Large-scale screening applications require methods that are rapid, accurate, provide low detection limits and are free from interference. The problem is further complicated by the wide range of chemical functionalities and modes of operation exhibited by the antibiotic materials of physiological significance in use today. As demonstrated, chromatographic methods provide many of the advantages necessary for screening applications. Judicious choice of sample preparation method, separation mode and detection strategy can provide significant immunity from problems associated with the food matrix. Gas chromatography can provide extremely high separation efficiencies, however, only a limited number of antibiotic compounds are inherently volatile enough for direct analysis by gas chromatography. Derivatization to enhance the volatility of the antibiotic is one approach to overcome this limitation. Among the methods available, reversed-phase high-performance liquid chromatography is used extensively for the analysis of many antibiotic systems as it does not require derivatization and it combines relatively high separation efficiencies with low detection limits. The diverse group of properties exhibited by the antibiotic materials in use today suggests that the choice of detection strategy is a key component in the successful development of an analysis technique. Derivatization of the antibiotic material is frequently used to add either a fluorogenic of chromogenic moiety to the antibiotic compound to enhance detection. Derivatization procedures suffer from several limitations which are problematic when making measurements in complicated food matrices. Among the different detection modes utilized for antibiotic analysis, polarimetric detection has the potential to provide extremely selective detection of most antibiotic materials, and this selective response can minimize many of the constraints placed upon the separation system by the sample matrix. Although many of the separation modes used for antibiotic analysis are well developed, separations based on capillary electrophoretic methods have much potential in the field of antibiotic analysis. Future investigations are needed to extend the generality of these techniques and expand their use into the field of food analysis.