Problem

Sorry for that.
I forgot to remove that when I pasted the code for forum.
Just now I burned this 'exact' code in all 3 Arduinos. As before, only 2 are working.

#include <SD.h>
#include <Wire.h>
#include <SPI.h>
int CS_pin = 4;
int SD_led = 8;
#include "floatToString.h"
#include "RTClib.h"
RTC_DS1307 RTC;
float COValue = 0;
float NO2Value = 0;
float O3Value = 0;
float e_NO2Value = 0;
float e_NOValue = 0;
float e_COValue = 0;
float celsius = 0, kelvin=0;
#include <math.h>
int dustPin=0;
int ledPower=2;
int delayTime=280;
int delayTime2=40;
float offTime=9680;
float ZeroPercentVoltage = 0.8;
float val = 0;
float RH = 0;
float max_voltage = 3.27;

  char date_time[10];
  char CO_Vout[10];
  char NO2_Vout[10];
  char O3_Vout[10];
  char cel[10];
  char hum[10];
  char e_NO2_Vout[10];
  char e_NO_Vout[10];
  char e_CO_Vout[10];

void setup()
{
  Wire.begin();
  Serial.begin(9600);
  SPI.begin();
  Serial.println("Initializing Card");
  pinMode(53, OUTPUT);
  //digitalWrite(53, HIGH);
  RTC.begin();
  pinMode(ledPower,OUTPUT);
  pinMode(5, OUTPUT);
  if (!SD.begin(CS_pin))
  {
      Serial.println("Card Failure");
      return;
  }
  Serial.println("Card Ready");
  
  //Write Log File Header
  File logFile = SD.open("LOG.csv", FILE_WRITE);
  if (logFile)
  {
    logFile.println(", , , , , , , , ,"); //Just a leading blank line, incase there was previous data
    String header = "Date_Time, Temp, Humidity(%), e_NO2_Vout, e_NO_Vout, e_CO_Vout, CO_Vout, NO2_Vout, O3_Vout, Dust_Vout";
    logFile.println(header);
    logFile.close();
    Serial.println(header);
  }
  else
  {
    Serial.println("Couldn't open log file");
  }
  
}

void loop()
{

  NO2Value = analogRead(1) * 0.004882812;
  COValue = analogRead(2) * 0.004882812;
  O3Value = analogRead(3) * 0.004882812;
  
  kelvin = analogRead(4) * 0.004882812 * 100;
  celsius = (kelvin - 273.15) - 15;
  
  val = analogRead(5);
  max_voltage = (3.27-(0.006706*celsius));
  RH = ((((val/1023)*5)-ZeroPercentVoltage)/max_voltage)*100;
  
  digitalWrite(ledPower,LOW);
  delayMicroseconds(delayTime);
  int dust_Vout = analogRead(dustPin);
  delayMicroseconds(delayTime2);
  digitalWrite(ledPower,HIGH);
  delayMicroseconds(offTime);
  
  e_NO2Value = analogRead(8) * 0.004882812;
  e_NOValue = analogRead(9) * 0.004882812;
  e_COValue = analogRead(10) * 0.004882812;
  
  floatToString(CO_Vout, COValue, 8);
  floatToString(NO2_Vout, NO2Value, 8);
  floatToString(O3_Vout, O3Value, 8);
  floatToString(cel, celsius, 1);
  floatToString(hum, RH, 1);
  floatToString(e_NO2_Vout, e_NO2Value, 8);
  floatToString(e_NO_Vout, e_NOValue, 8);
  floatToString(e_CO_Vout, e_COValue, 8);
  
  DateTime now = RTC.now();
  sprintf(date_time,"%d/%d/%d %d:%d:%d",now.day(),now.month(),now.year(),now.hour(),now.minute(),now.second());
  String dataString = String(date_time) + ", " + String(cel) + ", " + String(hum) + ", " + String(e_NO2_Vout) + ", " + String(e_NO_Vout) + ", " + String(e_CO_Vout) + ", " + String(CO_Vout) + ", " + String(NO2_Vout) + ", " + String(O3_Vout) + ", " + String(dust_Vout); 
  // String dataString = String(date_time) + ", " + String(cel) + ", " + String(hum) + ", " + String(CO_Vout) + ", " + String(NO2_Vout) + ", " + String(O3_Vout) + ", " + String(dust_Vout); 
  File logFile = SD.open("LOG.csv", FILE_WRITE);
  if (logFile)
  {
    logFile.println(dataString);
    logFile.close();
    Serial.println(dataString);
    pinMode(SD_led, OUTPUT);
    digitalWrite(SD_led, HIGH);
  }
  else
  {
    Serial.println("Couldn't open log file");
  }
  
  delay(60000);
  digitalWrite(SD_led, LOW);
}