[Psychological factors in the context of perioperative knee and joint pain: the role of treatment expectations in pain evolvement]. / Psychologische Faktoren im Kontext perioperativer Knie- und Gelenkschmerzen: die Rolle der Behandlungserwartungen für den Schmerzverlauf.

Chronic knee and joint pain, like all chronic pain, is a complex multidimensional event that involves somatic, psychological and social factors. Patients with knee and other joint pain experience limited mobility in their daily lives, in their professional and personal activities, and in their leisure physical exercise activities. Pain increasingly prevents them from achieving their goals. Psychological factors not only interact with neurobiological and immunological processes of pain, they play an important role in the development and maintenance of pain. Within that, expectations concerning the course of the disease and its treatment play a significant role. Study designs involving a placebo knee surgery show the high influence of these variables. The patients receiving the verum surgery do not report-as expected-less pain or better functioning than those receiving a placebo surgery. This significant influence of psychological factors may be clinically relevant. A positive patient-staff relationship-characterized by trust, warmth and empathy-is essential in order to achieve optimal therapeutic efficacy of a treatment. Every surgeon, pain physician, pain psychologist or pain physiotherapist is responsible for establishing a trusting interpersonal relationship between themselves and their patients.

Avaliação diagnóstica na síndrome disfunção cognitiva canina / Diagnostic Evaluation of Canine Cognitive Dysfunction Syndrome

O objetivo do presente estudo foi avaliar o questionário observacional e os testes de reatividade como forma de triagem e diagnóstico da disfunção cognitiva em cães idosos. Foram estudados 10 cães acima de sete anos, que apresentavam queixas comportamentais. Foi utilizado questionário que abordava questões comportamentais, como desorientação, atividade, interação socioambiental, alterações no padrão do sono e casa-sujidade. As respostas foram convertidas em pontuações, cujo somatório classificou o cão com disfunção cognitiva canina (DCC), ou borderline (BL), ou sem alterações comportamentais (SAC). Logo depois, foram realizados, em todos os cães, os seguintes testes cognitivos: open field, curiosidade, interação com humano e com espelho. Pela avaliação do questionário, foi determinado que dois cães tinham DCC, três eram BL, cinco eram SAC. Os cães classificados com DCC tinham idade superior aos demais e apresentaram alterações em todos os testes de reatividade, enquanto os cães BL apresentaram alterações em dois testes de reatividade e os SAC não apresentaram alterações. Conclui-se que, com o aumento da expectativa de vida canina, o questionário observacional foi um instrumento de triagem para a identificação dos cães classificados com DCC, BL e SAC, e os testes de reatividade como um método inovador para identificar o verdadeiro estado cognitivo dos pacientes idosos.(AU)

The objective was to evaluate the observational questionnaire and the reactivity tests as a way of screening and diagnosis of cognitive dysfunction in elderly dogs. Ten dogs over seven years of age, with behavioral complaints, were studied. A questionnaire was used that addressed behavioral issues such as disorientation, activity, socioenvironmental interaction, changes in sleep pattern, and house-dirtiness. Responses were converted into scores, which summed the dog with canine cognitive dysfunction (DCC), or Borderline (BL) or without behavioral changes (SAC). Soon after, the following cognitive tests were performed on all dogs: open field, curiosity, interaction with human and with mirror. Through questionnaire evaluation, two dogs had CHD, three were BL, and five were SAC. The dogs classified with DCC were older than the others and presented alterations in all reactivity tests, while the BL dogs presented changes in two reactivity tests and CAD showed no alterations. With the increase in canine life expectancy, the observational questionnaire was a screening instrument for the identification of dogs classified with DCC, BL and SAC and the reactivity tests as an innovative method to identify the true cognitive status of the dogs elderly patients.(AU)

Aspectos clínicos e laboratoriais da mastite induzida por inoculação intramamária de Staphylococcus aureus em vacas e búfalas / Clinical and laboratory aspects of mastitis induced by intramammary inoculation of Staphylococcus aureus in cows and buffaloes

Vários aspectos relacionados à mastite bubalina precisam ser esclarecidos. Muitas condutas são adaptadas a essa espécie pelo conhecimento adquirido com a espécie bovina. Com este experimento, objetivou-se evidenciar particularidades da mastite em búfalas e vacas que tiveram uma glândula inoculada com 1,0 x 103 UFC de S. aureus. Os animais foram monitorados por cultura bacteriana do leite, California Mastitis Test (CMT), e escores para avaliação da severidade da mastite. Foram utilizados os seguintes critérios: temperatura retal, apetite, produção de leite (resposta sistêmica à inflamação), contagem de células somáticas (CCS), aparência/consistência da glândula e aparência da secreção láctea (resposta localizada à inflamação). Todos os animais desenvolveram mastite clínica superaguda. A bactéria foi recuperada de todas as glândulas desafiadas, sem diferença significativa no percentual de isolamento entre as espécies até o 11º dia pós-inoculação, porém com diferença (P<0,001) no 30º dia pós-inoculação. A CCS pelo método eletrônico e o CMT detectaram nas búfalas resposta mais intensa logo após a inoculação e diminuição mais rápida da contagem ao final do experimento, quando se comparou essa espécie com as vacas. Ambos os testes demonstraram correlação com a cultura bacteriana. Na avaliação da severidade da mastite, as médias do escore total, do escore da resposta local e do escore da resposta sistêmica foram mais elevadas na espécie bovina (P<0,05). Ao longo do período de observação, verificou-se uma capacidade superior das búfalas em recuperar o status sanitário adequado, chegando, ao final do experimento, com os parâmetros avaliados mais próximos dos fisiológicos...

Several aspects related to bubaline mastits need to be clarified. Many conducts are adapted to this species by the knowledge adquired with the bovine species. This experiment aimed to evidence particularities of mastits in buffaloes and cows submitted to one-gland inoculation with 1.0 x 103 CFU of S. aureus. The animals were monitored through bacterial culturing milk, California Mastitis Test (CMT) and scores to assess the severity of mastitis. The following criteria were used: rectal temperature, appetite, milk production (systemic response to inflammation), somatic cell count (SCC), appearance/consistency of the gland and appearance of the milk secretion (localized response to inflammation). All animals developed hyperacute clinical mastitis. The bacteria was recovered from all challenged glands, with no significant difference in the percentage of isolation between the species until day 11 after inoculation, but with a difference (p<0.001) on day 30 post inoculation. The SCC with the electronic method and CMT, detected in buffaloes a more intense response right after the inoculation and a faster decrease of counting by the end of the experiment, when compared to cows. In both tests correlation with the bacterial culture was detected. In assessing the severity of mastitis, the averages of total score, of the score of local response and the systemic response score were higher in the bovine species (P<0.05). Throughout the observation period, there was a higher capacity of buffaloes in reaching the appropriate sanitary status, coming to the end of the experiment with the parameters closer to the physiological...

Study of environmental burden of lead in children using teeth as bioindicator.

The south region of Sao Paulo city hosts the Guarapiranga dam, responsible for water supply to 25% of the city population. Their surroundings have been subject to intense and irregular occupation by people from very low socioeconomics classes. Measurements undertaken on sediment and particulate materials in the dam revealed concentrations of lead, copper, zinc and cadmium above internationally accepted limits. Epidemiological and toxicological studies undertaken by the World Health Organization in individuals exhibiting lead concentrations in blood, near or below the maximum recommended (10 microg dl(-1)), surprisingly revealed that toxic effects are more intense in individuals belonging to low socioeconomics classes. Motivated by these facts, we aimed at the investigation of chronic incorporation of lead, as well as the use of our BIOKINETICS code, which is based on an accepted ICRP biokinetics model for lead, in order to extrapolate the results from teeth to other organs. The focus of our data taking was children from poor families, living in a small, restrict and allegedly contaminated area in São Paulo city. Thus, a total of 74 human teeth were collected. The average concentration of lead in teeth of children 5 to 10 years old was determined by means of a high-resolution inductively coupled plasma mass spectrometer (ICP-MS). For standardization of the measurements, an animal bone certified material (H-Animal Bone), from the International Atomic Energy Agency, was analyzed. The amount of lead in children living in the surroundings of the dam, was approximately 40% higher than those from the control region, and the average lead concentration was equal to 1.3 microg g(-1) approximately. Grouping the results in terms of gender, tooth type and condition, it was concluded that a carious molar of boys is a much more efficient contamination pathway for lead, resulting in concentrations 70% higher than in the control region. We also inferred the average concentrations of lead in other organs of these children, by making use of our BIOKINETIC code.

[Evaluation of tibial torsion--comparison of clinical methods and computed tomography]. / Bestimmung der Tibiatorsion--Vergleich von klinischen Winkelmessungen zur Computertomographie.

PURPOSE: To determine variability between clinical goniometric methods and computed tomography (CT) in measuring posttraumatic malrotation of the tibia. MATERIALS AND METHODS: In a prospective study, absolute tibial torsion of both legs after unilateral fracture of the tibia as well as the difference between both legs (intra-individual torsional difference) was postoperatively determined with two goniometric and two CT methods in 40 patients (female : male = 16 : 24, mean age = 46 +/- 34 years). RESULTS: The mean difference between goniometric and CT methods in determining intra-individual torsional difference was not significant. Nevertheless, variance of values was higher in goniometric measurement (up to +/- 11 degree), with the measurements of torsional difference showing two times greater standard deviation in interobserver variability of goniometric methods as compared to CT. CONCLUSION: Goniometric methods do not significantly differ from the CT methods for determination of intraindividual torsional difference. The higher variance of interobserver values limits accuracy of goniometric methods. Therefore, goniometric determination of tibial torsion can only be considered an estimate but not a precise measurement.

[Manipulation of the step borer as cause of too shallow boring depth in the femoral neck with the gamma nail system]. / Handhabung des Stufenbohrers als Ursache für eine zu geringe Bohrtiefe im Schenkelhals beim Gamma-Nagelsystem.

The gamma nail step drill has been sold over 500,000 times worldwide. Depending on the construction used and the way it is handled, it can lead to a drill depth in the femoral head that is too shallow if the anatomic dimension of the femoral neck is rather long. Whenever the relationship between rotational speed and drive force is unfavorable, as it is by hand reaming, the triple-bladed drill only produces a triangular hole in the lateral cortical bone. Subsequently, it draws itself through this hole like a screw, without forming the hole into a complete circle. The drill shaft expands conically along its length preventing it from passing through the hole in the cortical bone at a depth of 90 mm. Until now, this phenomenon has been traced back to blunt drills or perhaps curved guide wires. Since the lag screws that have been used could not be screwed into undrilled cancellus bone, screws have sometimes been implanted at a sub-optimal length. The problem was noticed, however, and documented in experiments, and potential solutions were proposed.

Determination of Cd and Pb in food slurries by GFAAS using cryogenic grinding for sample preparation.

A simple method combining slurry sampling after cryogenic grinding and the use of a permanent modification of the integrated platform inside the transversely heated graphite atomizer (THGA) was proposed for the determination of Cd and Pb in foods. Potentialities of the cryogenic grinding were evaluated for grinding different materials of difficult homogenization such as high fat and high fiber tissues. Animal and vegetal samples were cut into small pieces and ground in liquid nitrogen for 2 min. Slurries were prepared directly in the autosampler cup after cryogenic grinding by transferring an exact amount of homogeneous powdered material (5-20 mg) to the cup, followed by 1.00 mL of 0.2% (v/v) HNO3 containing 0.04% (v/v) Triton X-100 and sonication for 30 s, before transferring into the platform previously coated with 250 microg W and 200 microg Rh. Use of a tungsten carbide-rhodium permanent modifier combined with NH4H2PO4 conventional modifier improves tube lifetime and increases the pyrolysis temperature for Cd. Homogeneity tests, carried out by comparing the between- and within-batch precision for each kind of sample, showed no significant differences at the 95% confidence level, indicating good homogeneity for 5-20 mg masses. Detection limits were 3.3 ng g(-1) Cd and 75 ng g(-1) Pb for 1% m/v slurries. Results for determination of Cd and Pb in foods slurries were in agreement with those obtained with digested samples, since no statistical differences were found by the paired t-test at the 95% level.

[Quality of life assessment after surgery for diverticulitis - a follow-up study]. / Lebensqualität nach chirurgischer Therapie einer Divertikulitis - Ergebnisse im Follow-up -

BACKGROUND: Laparoscopic sigmoid resection is a well established procedure for surgical treatment of benign colorectal diseases. The aim of the present study was to assess the longterm quality of life of patients who underwent laparoscopic sigmoid resection for sigmoid diverticulitis. Differences in health related life quality to the open-conventional approach were evaluated in a matched pair analysis (age, gender, Hinchey-Stage, Type of Surgery) using a validated quality of life instrument. METHODS: A total of 45 matched pairs (laparoscopic/open) operated for diverticulitis at stage I-IIa (Hinchey classification) were included in this study. The quality of life was measured with the Short-Form-36-Health Survey (SF-36), a standardized questionnaire with 8 scales and 36 items. The follow-up period was at least 2 years (mean 62.2 months). RESULTS: Pair members (n = 45) operated via laparoscopic or open approach for Hinchey I-IIa diverticulitis were of the same sex (21 female/24 male pairs) and age at time of surgery (range: lap.: 53.5-66 years; open: 53.5-67 years). Mean follow-up periods for patients operated laparoscopically and with open procedure were 2 (range: 1-3) and 7 (range: 5-9) years, respectively. The SF-36 scale scores for both groups appeared high and only slightly below a validated norm population. This represents a high quality of life after open as well as laparoscopic surgery for sigmadiverticulitis. No significant differences were apparent between the 45 matched-pairs. Pairs 65 years old or older presented no significantly different score values compared to those younger than 65 years. CONCLUSIONS: The long-term follow-up data in this age and sex matched pair analysis showed favorable results after open as well as laparoscopic surgery for sigmadiverticulitis. No statistically significant differences were observed between the two surgical techniques. Self-reports by the patient concerning his or her health condition, recovery and quality of life following any surgical procedure are needed to assess valid outcome data of new surgical treatments including a critical evaluation of all its benefits and burdens.

[Blunt trocar with modified tip for open laparoscopy]. / Wechselstab mit modifizierter Spitze für die offene Laparoskopie.

A blunt trocar for open laparoscopy is presented. Its modified design leads to better visual control of the trocar tip during insertion. Thus the risk of misplacement of the trocar is reduced.

Lead determination in slurries of biological materials by ETAAS using a W-Rh permanent modifier.

A tungsten-rhodium coating on the integrated platform of a transversely heated graphite atomiser (THGA) was used as a permanent chemical modifier for the determination of lead in biological materials by slurry sampling in electrothermal atomic absorption spectrometry (ETAAS). Slurries were sonicated during 20 s before being delivered to the previously W-Rh treated platform. The number of particles of biological materials introduced into the atomiser for delivering 20 microL slurry aliquot ranged from 5,100 to 39,000. The permanent W-Rh modifier remained stable during approximately 300 analytical measurements when 20 microL of slurries containing up to 1.5% m/v were delivered into the atomiser. In addition, the permanent modifier increases the tube lifetime by approximately 100% when compared to untreated integrated platforms. Also, there is less decrease of sensitivity during the atomiser lifetime when compared with the conventional modifiers, resulting in a decreased need of re-calibration during routine analysis and consequently increasing the sample throughput. The atomiser lifetime was limited to the THGA wall durability, because the W-Rh treated platform was intact after more than 650 analytical firings in a medium containing up to 1.5% m/v slurry of biological material. The detection limit based on integrated absorbance was 20 ng g(-1) Pb for 1.50% m/v slurries. Results from the determination of lead in slurries of biological materials using the W-Rh permanent modifier were in agreement with those obtained with digested solutions using Pd + Mg(NO3)2.

[Spiral trocar--a new trocar concept]. / Der Spiraltrokar--ein neues Trokarkonzept.

INTRODUCTION: We would like to introduce a new trocar technique for minimal invasive surgery. The new trocar is a spiral whose coil becomes ever increasingly stronger towards the centre. Because of this, there is a smooth transition between spiral, screw and rod. The outer diameter remains the same. The spiral-trocar is screwed through the abdominal wall like a corkscrew. Because of this, the primary channel of puncture runs spirally. Furthermore, the channel is dilated and centralised so that the trocar's rod together with its sleeve can be pushed through the abdominal wall. This trocar design demonstrates the following advantages: The trocar can be screwed through the abdominal wall in a controlled manner without having to apply axial pressure. This prevents any unintentional perforation of organs. Because different layers of the tissue are penetrated at different places, they overlap, thus sealing one another after removal of the sleeve. The puncture channel was minimal, thus leaving very little risk of trocar site hernia. METHODS: The spiral-trocar was examined and compared with other types of trocars in vivo and vitro. RESULTS: During these tests, the spiral-trocar demonstrated a high level of safety and good usability. DISCUSSION: The spiral-trocar is an easily cleanable, reusable product without a mechanical sealing device and can be used together with most sleeves. This makes it very cost effective.

Mercury fluxes in a natural forested Amazonian catchment (Serra do Navio, Amapá State, Brazil).

Mercury (Hg total) fluxes were calculated for rainwater, throughfall and stream water in a small catchment located in the northeastern region of the Brazilian Amazon (Serra do Navio, Amapá State), whose upper part is covered by a natural rainforest and lower part was altered due to deforestation and activities related to manganese mining. The catchment area is 200 km from the nearest gold mining (garimpo). Minimum and maximum Hg concentrations were measured monthly from October 1996 to September 1997 and were 3.5-23.4 ng l(-1) for rainwater, 16.5-82.7 ng l(-1) for throughfall (March-August 1997) and 1.2-6.1 and 4.2-18.8 ng l(-1) for stream water, in natural and disturbed areas, respectively. In the natural area, the inputs were 18.2 microg m 2 year(-1) in rainwater and 72 microg m(-2) year(-1) in throughfall. This enrichment was attributed to dry deposition. The stream output of 2.9 microg m(-2) year(-1) indicates that Hg is being recycled within the forest as other chemical species or is being retained by the soil system, as confirmed by the cumulative Hg burden in the 0-10 cm surface layer, which was 36480 microg m(-2). When the disturbed area of the catchment was included, the stream output was 9.3 microg m(-2), clearly indicating the impact of the deforestation of the lower part of the basin on the release of mercury. The Hg burden in the disturbed area was 7560 microg m(-2) for the 0-10 cm surface layer.

Ordinary colorectal adenocarcinoma vs. primary colorectal signet-ring cell carcinoma: study matched for age, gender, grade, and stage.

PURPOSE: This study contributes to the characterization of primary colorectal signet-ring cell cancer in contrast to ordinary colorectal carcinoma. Primary colorectal signet-ring cell cancer is a rare but distinctive primary neoplasm of the large bowel with still-controversial clinicopathologic features. METHODS: Clinicopathologic features and survival data are evaluated in comparison with those of the ordinary colorectal adenocarcinoma (non-signet colorectal carcinoma) in a retrospective study matched for age, gender, grade, and stage. RESULTS: In a series of 1,600 consecutive colorectal cancer patients since 1979, 14 patients (0.88 percent) with a signet-ring cell cancer were identified. Gender ratio was balanced, and mean age was 67.5 years. The majority of patients had an advanced tumor stage at the time of diagnosis (57.1 percent Stage IV and 35.7 percent Stage III). Median survival time was only 16 months. In a study matched for age, gender, grade, and stage, a lower survival rate was found for patients with signet-ring cell cancer, but the difference did not reach statistical significance. In contrast to non-signet colorectal carcinoma, signet-ring cell cancer was characterized by a significantly higher incidence of peritoneal tumor spread (64.3 percent) and a lower incidence of hepatic metastases (14.3 percent). CONCLUSIONS: Signet-ring cell cancer represents a rare but distinctive primary neoplasm of the large bowel. It is frequently diagnosed in an advanced tumor stage, thus showing an overall poorer prognosis than nonsignet colorectal carcinoma. Usually only palliative surgery is possible. A high incidence of peritoneal seeding and a low incidence of hepatic metastasis is characteristic of signet-ring cell cancer.

Atomization of Al in a tungsten coil electrothermal atomic absorption spectrophotometer.

Electrothermal atomic absorption spectrophotometry of Al in a tungsten coil atomizer was evaluated and applied for its determination in hemodialysis fluid. The system was mounted on a Varian Spectra AA-40 spectrophotometer with continuum background correction and all measurements, in peak height absorbance, were done at 309.3 nm. The purge gas was a mixture of 90% Ar plus 10% H(2). Observation height, gas flow, drying, pyrolysis and atomization steps were optimized. The heating program was carried out by employing a heating cycle in four steps: dry, pyrolysis, atomization and clean. The determination of Al in hemodialysis solutions was performed by using a matrix-matching procedure. Al in hemodialysis solutions was determined by TCA and by electrothermal atomization with a graphite tube atomizer. There is no differences between results obtained by both methods at a confidence level of 95%. The characteristic mass of Al by using the TCA was 39 pg and the detection limit was 2.0 mug l(-1).

Blood selenium and glutathione peroxidase status in patients with colorectal cancer.

PURPOSE: It is still controversial whether a low selenium level and a reduced activity of the selenium-dependent enzyme, glutathione peroxidase, in blood are associated with an increased risk and poor prognosis of cancer in humans. This study evaluates whether colorectal cancer patients have lower serum selenium and glutathione peroxidase levels than a gender-matched and age-matched control group and whether there is a correlation to clinical data and prognosis. METHODS: In a retrospective study, serum selenium and glutathione peroxidase activity of 106 patients with colorectal cancer were determined. Clinical data were provided by our long-term follow-up program for colorectal cancer patients. RESULTS: Patients with a selenium level <70 microg/l had a significantly lower mean survival time and a lower cumulative cancer-related survival rate than patients with a selenium level >70 microg/l (P = 0.0009). When considering the different tumor stages, a decline of the mean selenium level in the T4 carcinoma group was found in the analysis of variance (P < 0.05). The lowest selenium level was found for patients with advanced tumor disease and in a preoperative situation, ie., high tumor burden. In comparison with the control group, the cancer group showed a significant reduction of serum glutathione peroxidase activity (P < 0.01) but no significant difference in selenium level. CONCLUSIONS: These results support the hypothesis of an association between low selenium level and advanced tumor disease. From our data, it cannot be decided whether this phenomenon is more likely to be a consequence or a causative factor for development and course of the disease.

Determination of ytterbium in animal faeces by tungsten coil electrothermal atomic absorption spectrometry.

A method for ytterbium determination in animal faeces by tungsten coil electrothermal atomic absorption spectrometry (TCAAS) was developed. Faeces were dry-ashed in a muffle furnace, the ashes were treated with hydrochloric acid, and 10 mul of sample solution were delivered into 150-W tungsten coil atomizer. A matrix-matching procedure employing a 66-s heating program proved to be efficient for obtaining accurate results. Characteristic mass and detection limit were 7.1 pg and 0.35 mug g(-1) Yb, respectively. The tungsten coil atomizer lifetime exceeded 300 firings with digested solutions and R.S.D. of measurements was 1.9% after ten consecutive injections of 10.0 mug l(-1) Yb. Accuracy of the proposed method was assessed by employing a graphite furnace atomic absorption spectrometric procedure. Application of the paired t-test did not reveal any significant difference for ytterbium contents determined by both methods at 95% confidence level. It was demonstrated that the proposed procedure can successfully be used for evaluation of kinetic passage rate of feed through digestive tract of animals.

Laparoscopic implantation of Oreopoulos-Zellermann catheters for peritoneal dialysis.

For the implantation of continuous ambulatory peritoneal dialysis (CAPD) catheters, both the laparoscopic technique and the use of an Oreopoulos-Zellermann catheter have been suggested to be preferable to the open technique using Tenckhoff catheters. Building on advantages of known techniques, we here describe a procedure for the laparoscopic implantation of the Oreopoulos-Zellermann catheter. The procedure is quick, efficient and unstressful to the patient. After nearly 10,000 patient-days of catheter use, we find positive results with regard to permanently good inlet and outlet flows, low incidence of exit site infections and leaks from the catheter tunnel.

[Laparoscopic implantation of Oreopoulos-Zellermann catheters for peritoneal dialysis]. / Laparoskopische Anlage von Oreopoulos-Zellermann-Kathetern zur Peritonealdialyse.

For the insertion of CAPD-catheters the laparoscopic implantation technique and the use of Oreopoulos-Zellermann catheters have been shown to be advantageous if compared with the open technique using Tenckhoff catheters. The implantation procedure shown here makes it possible to place the Oreopoulos-Zellermann catheter laparoscopically, combining different advantages. The procedure is quick, efficient and not stressful for the patients. After 4700 days of catheter-use in the patients positive results are seen with regard to permanently good inlet and outlet flows, low incidences of catheter exit site infections and leakages of the catheter tunnel.

Correction of iron interface in the spectrophotometric flow injection catalytic determination of molybdenum in plants.

Iron interference in the spectrophotometric catalytic determination of molybdenum based on the iodide-hydrogen peroxide reaction can be corrected by using sulphosalicylic acid as masking and color-forming reagent. The catalytic influence of iron ions is circumvented to the extent of about 90% and correction of any remaining iron ions is possible by monitoring the colored iron(III)-salicylate complex at 490 nm. In this way, iron is also determined. With the proposed system, molybdenum can be determined in plant and food digests within the 0-100 mug Mo 1(-1) range in the presence of up to 25 mg Fe 1(-1), at a sampling rate of about 50 determinations h(-1). The relative standard deviation of 10 consecutive measurements was estimated as < 2%. Results for samples were comparable with those obtained by graphite furnace atomic absorption spectrometry. In addition, recoveries within the range 94-100% were calculated.