Lactate determination

Pyronin B, fluorometry, 640 Pyruvate, lactate determination, 625, 626 Pyruvic acid, hydrogen peroxide determination, 655... 

B. Serra, A.J. Reviejo, C. Parrado and J.M. Pingarron, Graphite-Teflon composite bienzyme electrodes for the determination of L-lactate application to food samples, Biosens. Bioelectron., 14(5) (1999) 505-513. A.A.J. Torriero, E. Salinas, F. Battaglini and J. Raba, Milk lactate determination with a rotating bioreactor based on an electron transfer mediated by osmium complexes incorporating a continuous-flow/ stopped-flow system, Anal. Chim. Acta, 498(1-2) (2003) 155-163. 

A.A.J. Torriero, E. Salinas, F. Battaglini and J. Raba, Milk lactate determination with a rotating bioreactor based on an electron transfer mediated by osmium complexes incorporating a continuous-flow/stopped-flow system, Anal. Chim. Acta, 498 (2003) 155-163. 

Enzyme electrodes for lactate determination using immobilized lactate dehydrogenase 16), for urea determination using immobilized urease 17), for L-amino acids using immobilized L-amino acid oxidase 18), and for various amines using the appropriate immobilized deaminase system (19) have also been prepared. A urease electrode is commercially available from Beckman,... 

L-Lactate is an intermediate product of carbohydrate metabolism. An increase in blood lactate concentration caused by oxygen deprivation of tissues and liver disease makes lactate a relevant indicator in clinical and sports medicine. The normal concentration in blood is up to 2.7 mmol/1 strenuous exercise may raise it to 25 mmol/1. Lactate determination is also of interest in the food and microbiological industries. 

The enzyme reactions applicable in biosensors for lactate determination are shown in the following scheme ... 

The mediator NMP has been used for lactate determination with a platinum electrode in front of which LDH and dextran-bound NAD ... 

LDH(PQQ) is a quinoprotein requiring neither oxygen nor nicotinamide cofactors for lactate oxidation. The enzyme has been coupled to a ferrocene-modified carbon electrode (Turner, 1985). The sensor was useful for lactate determination up to 4 mmol/1 but within 5 h the sensitivity dropped to 5%. 

Cytochrome b2 from Hansenula anomala has been employed for lactate determination in the Glukometer GKM 02 analyzer (ZWG, GDR). When immobilized in gelatin or poly(vinyl alcohol) the enzyme was stable for 15 days. Linearity was obtained over the range 10 (jmol/1-2.4 mmol/1, the upper limit being adjustable by the mediator concentration used. With the rate method a sample frequency of 40/h and a CV below 2% were achieved. In a flow-through device the CV was below 1% (Schubert and Weigelt, 1986). 

Scheller et al. (1986a) combined polyurethane-immobilized LOD with an Au/Pd-sputtered carbon electrode. The electrode modification permits H2O2 to be electrochemically oxidized at a potential as low as +450 mV, where interferences by other anodically oxidizable compounds such as NADH and ascorbic acid are largely reduced (Fig. 57). This increased selectivity also enables the measurement of LDH activity. The sensor has been introduced in an FIA manifold. A sample frequency of 200Ai (Fig. 58) and a CV below 1% were obtained with this setup. A platinum electrode with LOD covalently bound to a nylon membrane has been employed for continuous blood lactate determination in an artificial pancreas by Mascini et al. (1985b, 1987). 

The normal lactate concentration in blood is between 1.2 and 2.7 mmol/1. For accurate lactate determination hemolysis of the sample is required to account for the (low) lactate content of erythrocytes. On the other hand, the glycolytic reactions in the sample have to be efficiently and rapidly inhibited in order to avoid lactate formation. Therefore the best-suited sample material is deproteinized blood however, the time period inevitably required for its preparation prevents rapid lactate assay. That is why the study of blood lactate sensors focuses not only on the sensor itself but also on the rapid pretreatment of blood samples. 

The selectivity of the YSI 23L has been substantially increased by replacing the cellulose acetate membrane by a cellulose acetate-butyrate membrane (Weil et al., 1986). This membrane prevents the permeation of anodically oxidizable drugs, such as paracetamol and amino-guanidine, to the electrode surface. The analyzer has been successfully used for lactate determination in spinal fluid (Clark et al., 1984a). 

Polyurethane-immobilized LOD is being used for whole blood lactate determination in the Glukometer as well as in the ECA 20 (ESAT 6660). Dilution of the samples with the buffer described in Section 5.2.3.1 provides both complete inhibition of glycolysis and immediate hemolysis. As is shown by the correlation equations the method is quite reliable ... 

Glucose and lactate determination. After 24 h incubation, no evidence of glucose consumption modification was present (data not shown), while after 48 h cells treated with monomers showed a significant increase of glucose consumption (p< 0.01) (Fig.4). HL-60 cells treated with monomers showed a statistically significant increase of lactate production (p<0.01). Cells treated with ATRA showed no significant difference vs control in glucose consumption or lactate production. 

Urea and lactate determined in l-/zL whole blood with a miniaturized thermal biosensor Analyst 120 155-60... 

U. Rydevik, L. Nord, and F. Ingman, Automatic Lactate Determination by Reagent Injection Analysis. Int. J. Sports Med., 3 (1982) 47. 

H. Weicker, FIA (Flow Injection Analysis) Is Also for Lactate Determination. Labor Praxis, 8 (1984) 300. 

Surprisingly, although the sensor measures only the lactate content of the plasma, whereas the results of the reference method reflect the concentration of lactate in both plasma and erythrocytes, the agreement between the two methods is good. The analyzer has also been used successfully for lactate determination in spinal fluid [370]. 

Martinez-Olmos A, Ballesta-Claver J, Palma A, Valencia-Mirdn MDC, Capitan-Vallvey L (2009) A portable luminometer with a disposable electrochemiluminescent biosensor for lactate determination. Sensors 9(10) 7694-7710... 

Ballesta Claver J, Valencia Miron MC, Capitan-Vallvey LF (2009) Disposable electrochemiluminescent biosensor for lactate determination in saliva. Analyst 134(7) 1423-1432. doi 10.1039/b821922b... 

An increased lactate concentration in CSF is an important indicator for CNS involvement. Increased lactate concentrations in blood are also indicative, but can easily be caused by stress (fear of venapuncture), excessive muscle contractions (status epilepticus), anoxia and other conditions. A reliable value is only obtained from two or more blood lactate determinations. Some patients with a proven mitochondrial defect do not show lactate accumulation in blood or urine, but CSF lactate is frequently increased. Urinary lactate excretion can be secondarily increased in some types of organic aciduria [2]. 

Ringer . lactate, a solution containing several different salts, is often administered intravenously for the initial treatment of trauma patients. One liter of Ringer s lactate contains 0.102 mole of sodium chloride, 4 X 10 mole of potassium chloride, 1.5 X 10 mole of calcium chloride, and 2.8 X 10 mole of sodium lactate. Determine the osmotic pressure of this solution at normal body temperature (37 C). Assume no ion pairing. (The formula of the lactate ion is CHiCH COO. )... 

Lactate is produced as a metabolic intermediate in humans and is a biomarker of human performance levels (Shah et ah, 2007). In the food industry, sodium, potassium, and calcium lactates (E number E325, E326, and E327, respectively) have been approved as food additives, and are used to regulate pH and as preservatives and flavoring agents. Lactate can also be used as a marker of fermentation (Avramescu et al., 2002) and a chemical indicator of flavor (Hemmi et al., 1995). Thus, determination of lactate concentrations is important not only for food process control but also for quality control of foods. In this chapter, we review flow injection analysis (FIA) for lactate determinations. 

Riddick et al., Pena-Tejedor et al. and Resa et al. measmed the normal boiling point (ambient pressure) of ethyl lactate, determining values of 427.7, 427.65, and 424.98K,... 

Jacobs E, Ancy JJ, Smith M (2002) Multi-site performance evahiatirai of pH, blood gas, electrolyte, glucose, and lactate determinations with the GEM Prtanier 3000 critical care analyzer. Point Care J Near-Patient Test Technol 1 135-144... 

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